diff --git a/.travis.yml b/.travis.yml
index ff263f2..cf1d136 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -3,6 +3,7 @@ python:
   - "2.6"
   - "2.7"
   - "3.3"
+  - "3.4"
   # - "pypy" - won't work as smmap doesn't work (see smmap/.travis.yml for details)
 
 script: nosetests
diff --git a/gitdb/__init__.py b/gitdb/__init__.py
index ff750d1..66d1b1c 100644
--- a/gitdb/__init__.py
+++ b/gitdb/__init__.py
@@ -12,14 +12,14 @@ def _init_externals():
     """Initialize external projects by putting them into the path"""
     for module in ('async', 'smmap'):
         sys.path.append(os.path.join(os.path.dirname(__file__), 'ext', module))
-        
+
         try:
             __import__(module)
         except ImportError:
             raise ImportError("'%s' could not be imported, assure it is located in your PYTHONPATH" % module)
         #END verify import
     #END handel imports
-    
+
 #} END initialization
 
 _init_externals()
@@ -32,7 +32,6 @@ def _init_externals():
 
 
 # default imports
-from db import *
-from base import *
-from stream import *
-
+from gitdb.base import *
+from gitdb.db import *
+from gitdb.stream import *
diff --git a/gitdb/base.py b/gitdb/base.py
index bad5f74..1eb4232 100644
--- a/gitdb/base.py
+++ b/gitdb/base.py
@@ -3,193 +3,193 @@
 # This module is part of GitDB and is released under
 # the New BSD License: http://www.opensource.org/licenses/bsd-license.php
 """Module with basic data structures - they are designed to be lightweight and fast"""
-from util import (
-        bin_to_hex,
-        zlib
-    )
+from gitdb.util import (
+    bin_to_hex,
+    zlib
+)
 
-from fun import (
-                    type_id_to_type_map,
-                    type_to_type_id_map
-                )
+from gitdb.fun import (
+    type_id_to_type_map,
+    type_to_type_id_map
+)
 
-__all__ = ('OInfo', 'OPackInfo', 'ODeltaPackInfo', 
+__all__ = ('OInfo', 'OPackInfo', 'ODeltaPackInfo',
             'OStream', 'OPackStream', 'ODeltaPackStream',
             'IStream', 'InvalidOInfo', 'InvalidOStream' )
 
 #{ ODB Bases
 
 class OInfo(tuple):
-    """Carries information about an object in an ODB, provding information 
+    """Carries information about an object in an ODB, provding information
     about the binary sha of the object, the type_string as well as the uncompressed size
     in bytes.
-    
+
     It can be accessed using tuple notation and using attribute access notation::
-    
+
         assert dbi[0] == dbi.binsha
         assert dbi[1] == dbi.type
         assert dbi[2] == dbi.size
-    
+
     The type is designed to be as lighteight as possible."""
     __slots__ = tuple()
-    
+
     def __new__(cls, sha, type, size):
         return tuple.__new__(cls, (sha, type, size))
-    
+
     def __init__(self, *args):
         tuple.__init__(self)
-    
-    #{ Interface 
+
+    #{ Interface
     @property
     def binsha(self):
         """:return: our sha as binary, 20 bytes"""
         return self[0]
-    
+
     @property
     def hexsha(self):
         """:return: our sha, hex encoded, 40 bytes"""
         return bin_to_hex(self[0])
-        
+
     @property
     def type(self):
         return self[1]
-    
+
     @property
     def type_id(self):
         return type_to_type_id_map[self[1]]
-        
+
     @property
     def size(self):
         return self[2]
     #} END interface
-    
-    
+
+
 class OPackInfo(tuple):
-    """As OInfo, but provides a type_id property to retrieve the numerical type id, and 
+    """As OInfo, but provides a type_id property to retrieve the numerical type id, and
     does not include a sha.
-    
-    Additionally, the pack_offset is the absolute offset into the packfile at which 
+
+    Additionally, the pack_offset is the absolute offset into the packfile at which
     all object information is located. The data_offset property points to the abosolute
     location in the pack at which that actual data stream can be found."""
     __slots__ = tuple()
-    
+
     def __new__(cls, packoffset, type, size):
         return tuple.__new__(cls, (packoffset,type, size))
-    
+
     def __init__(self, *args):
         tuple.__init__(self)
-        
-    #{ Interface 
-    
+
+    #{ Interface
+
     @property
     def pack_offset(self):
         return self[0]
-    
+
     @property
     def type(self):
         return type_id_to_type_map[self[1]]
-    
+
     @property
     def type_id(self):
         return self[1]
-        
+
     @property
     def size(self):
         return self[2]
-        
+
     #} END interface
-        
-        
+
+
 class ODeltaPackInfo(OPackInfo):
-    """Adds delta specific information, 
-    Either the 20 byte sha which points to some object in the database, 
+    """Adds delta specific information,
+    Either the 20 byte sha which points to some object in the database,
     or the negative offset from the pack_offset, so that pack_offset - delta_info yields
     the pack offset of the base object"""
     __slots__ = tuple()
-    
+
     def __new__(cls, packoffset, type, size, delta_info):
         return tuple.__new__(cls, (packoffset, type, size, delta_info))
-        
-    #{ Interface 
+
+    #{ Interface
     @property
     def delta_info(self):
         return self[3]
-    #} END interface 
-    
-    
+    #} END interface
+
+
 class OStream(OInfo):
-    """Base for object streams retrieved from the database, providing additional 
+    """Base for object streams retrieved from the database, providing additional
     information about the stream.
     Generally, ODB streams are read-only as objects are immutable"""
     __slots__ = tuple()
-    
+
     def __new__(cls, sha, type, size, stream, *args, **kwargs):
         """Helps with the initialization of subclasses"""
         return tuple.__new__(cls, (sha, type, size, stream))
-    
-    
+
+
     def __init__(self, *args, **kwargs):
         tuple.__init__(self)
-    
-    #{ Stream Reader Interface 
-    
+
+    #{ Stream Reader Interface
+
     def read(self, size=-1):
         return self[3].read(size)
-        
+
     @property
     def stream(self):
         return self[3]
-        
+
     #} END stream reader interface
-    
-    
+
+
 class ODeltaStream(OStream):
     """Uses size info of its stream, delaying reads"""
-    
+
     def __new__(cls, sha, type, size, stream, *args, **kwargs):
         """Helps with the initialization of subclasses"""
         return tuple.__new__(cls, (sha, type, size, stream))
-    
+
     #{ Stream Reader Interface
-    
+
     @property
     def size(self):
         return self[3].size
-        
+
     #} END stream reader interface
-    
-    
+
+
 class OPackStream(OPackInfo):
     """Next to pack object information, a stream outputting an undeltified base object
     is provided"""
     __slots__ = tuple()
-    
+
     def __new__(cls, packoffset, type, size, stream, *args):
         """Helps with the initialization of subclasses"""
         return tuple.__new__(cls, (packoffset, type, size, stream))
-        
-    #{ Stream Reader Interface 
+
+    #{ Stream Reader Interface
     def read(self, size=-1):
         return self[3].read(size)
-        
+
     @property
     def stream(self):
         return self[3]
     #} END stream reader interface
 
-    
+
 class ODeltaPackStream(ODeltaPackInfo):
     """Provides a stream outputting the uncompressed offset delta information"""
     __slots__ = tuple()
-    
+
     def __new__(cls, packoffset, type, size, delta_info, stream):
         return tuple.__new__(cls, (packoffset, type, size, delta_info, stream))
 
 
-    #{ Stream Reader Interface 
+    #{ Stream Reader Interface
     def read(self, size=-1):
         return self[4].read(size)
-        
+
     @property
     def stream(self):
         return self[4]
@@ -197,106 +197,106 @@ def stream(self):
 
 
 class IStream(list):
-    """Represents an input content stream to be fed into the ODB. It is mutable to allow 
+    """Represents an input content stream to be fed into the ODB. It is mutable to allow
     the ODB to record information about the operations outcome right in this instance.
-    
+
     It provides interfaces for the OStream and a StreamReader to allow the instance
     to blend in without prior conversion.
-    
+
     The only method your content stream must support is 'read'"""
     __slots__ = tuple()
-    
+
     def __new__(cls, type, size, stream, sha=None):
         return list.__new__(cls, (sha, type, size, stream, None))
-        
+
     def __init__(self, type, size, stream, sha=None):
         list.__init__(self, (sha, type, size, stream, None))
-    
-    #{ Interface 
+
+    #{ Interface
     @property
     def hexsha(self):
         """:return: our sha, hex encoded, 40 bytes"""
         return bin_to_hex(self[0])
-        
+
     def _error(self):
         """:return: the error that occurred when processing the stream, or None"""
         return self[4]
-        
+
     def _set_error(self, exc):
         """Set this input stream to the given exc, may be None to reset the error"""
         self[4] = exc
-            
+
     error = property(_error, _set_error)
-    
+
     #} END interface
-    
+
     #{ Stream Reader Interface
-    
+
     def read(self, size=-1):
-        """Implements a simple stream reader interface, passing the read call on 
+        """Implements a simple stream reader interface, passing the read call on
             to our internal stream"""
         return self[3].read(size)
-        
-    #} END stream reader interface 
-    
+
+    #} END stream reader interface
+
     #{  interface
-    
+
     def _set_binsha(self, binsha):
         self[0] = binsha
-        
+
     def _binsha(self):
         return self[0]
-        
+
     binsha = property(_binsha, _set_binsha)
-    
-    
+
+
     def _type(self):
         return self[1]
-    
+
     def _set_type(self, type):
         self[1] = type
-        
+
     type = property(_type, _set_type)
-    
+
     def _size(self):
         return self[2]
-        
+
     def _set_size(self, size):
         self[2] = size
-    
+
     size = property(_size, _set_size)
-    
+
     def _stream(self):
         return self[3]
-        
+
     def _set_stream(self, stream):
         self[3] = stream
-    
+
     stream = property(_stream, _set_stream)
-    
-    #} END odb info interface 
-        
+
+    #} END odb info interface
+
 
 class InvalidOInfo(tuple):
-    """Carries information about a sha identifying an object which is invalid in 
+    """Carries information about a sha identifying an object which is invalid in
     the queried database. The exception attribute provides more information about
     the cause of the issue"""
     __slots__ = tuple()
-    
+
     def __new__(cls, sha, exc):
         return tuple.__new__(cls, (sha, exc))
-        
+
     def __init__(self, sha, exc):
         tuple.__init__(self, (sha, exc))
-    
+
     @property
     def binsha(self):
         return self[0]
-        
+
     @property
     def hexsha(self):
         return bin_to_hex(self[0])
-        
+
     @property
     def error(self):
         """:return: exception instance explaining the failure"""
@@ -306,6 +306,5 @@ def error(self):
 class InvalidOStream(InvalidOInfo):
     """Carries information about an invalid ODB stream"""
     __slots__ = tuple()
-    
-#} END ODB Bases
 
+#} END ODB Bases
diff --git a/gitdb/const.py b/gitdb/const.py
new file mode 100644
index 0000000..147f79c
--- /dev/null
+++ b/gitdb/const.py
@@ -0,0 +1,5 @@
+from gitdb.utils.encoding import force_bytes
+
+NULL_BYTE = force_bytes("\0")
+NULL_HEX_SHA = "0" * 40
+NULL_BIN_SHA = NULL_BYTE * 20
diff --git a/gitdb/db/__init__.py b/gitdb/db/__init__.py
index e5935b7..0a2a46a 100644
--- a/gitdb/db/__init__.py
+++ b/gitdb/db/__init__.py
@@ -3,10 +3,9 @@
 # This module is part of GitDB and is released under
 # the New BSD License: http://www.opensource.org/licenses/bsd-license.php
 
-from base import *
-from loose import *
-from mem import *
-from pack import *
-from git import *
-from ref import *
-
+from gitdb.db.base import *
+from gitdb.db.loose import *
+from gitdb.db.mem import *
+from gitdb.db.pack import *
+from gitdb.db.git import *
+from gitdb.db.ref import *
diff --git a/gitdb/db/base.py b/gitdb/db/base.py
index 867e93a..53a94d2 100644
--- a/gitdb/db/base.py
+++ b/gitdb/db/base.py
@@ -4,22 +4,25 @@
 # the New BSD License: http://www.opensource.org/licenses/bsd-license.php
 """Contains implementations of database retrieveing objects"""
 from gitdb.util import (
-        pool,
-        join, 
-        LazyMixin, 
-        hex_to_bin
-    )
+    pool,
+    join,
+    LazyMixin,
+    hex_to_bin
+)
 
 from gitdb.exc import (
-                        BadObject, 
-                        AmbiguousObjectName
-                        )
+    BadObject,
+    AmbiguousObjectName
+)
 
 from async import (
-        ChannelThreadTask
-    )
+    ChannelThreadTask
+)
 
 from itertools import chain
+from functools import reduce
+
+import sys
 
 
 __all__ = ('ObjectDBR', 'ObjectDBW', 'FileDBBase', 'CompoundDB', 'CachingDB')
@@ -28,17 +31,17 @@
 class ObjectDBR(object):
     """Defines an interface for object database lookup.
     Objects are identified either by their 20 byte bin sha"""
-    
+
     def __contains__(self, sha):
         return self.has_obj
-    
-    #{ Query Interface 
+
+    #{ Query Interface
     def has_object(self, sha):
         """
         :return: True if the object identified by the given 20 bytes
             binary sha is contained in the database"""
         raise NotImplementedError("To be implemented in subclass")
-        
+
     def has_object_async(self, reader):
         """Return a reader yielding information about the membership of objects
         as identified by shas
@@ -46,62 +49,62 @@ def has_object_async(self, reader):
         :return: async.Reader yielding tuples of (sha, bool) pairs which indicate
             whether the given sha exists in the database or not"""
         task = ChannelThreadTask(reader, str(self.has_object_async), lambda sha: (sha, self.has_object(sha)))
-        return pool.add_task(task) 
-        
+        return pool.add_task(task)
+
     def info(self, sha):
         """ :return: OInfo instance
         :param sha: bytes binary sha
         :raise BadObject:"""
         raise NotImplementedError("To be implemented in subclass")
-        
+
     def info_async(self, reader):
         """Retrieve information of a multitude of objects asynchronously
         :param reader: Channel yielding the sha's of the objects of interest
         :return: async.Reader yielding OInfo|InvalidOInfo, in any order"""
         task = ChannelThreadTask(reader, str(self.info_async), self.info)
         return pool.add_task(task)
-        
+
     def stream(self, sha):
         """:return: OStream instance
         :param sha: 20 bytes binary sha
         :raise BadObject:"""
         raise NotImplementedError("To be implemented in subclass")
-        
+
     def stream_async(self, reader):
         """Retrieve the OStream of multiple objects
         :param reader: see ``info``
         :param max_threads: see ``ObjectDBW.store``
         :return: async.Reader yielding OStream|InvalidOStream instances in any order
-        
-        **Note:** depending on the system configuration, it might not be possible to 
+
+        **Note:** depending on the system configuration, it might not be possible to
             read all OStreams at once. Instead, read them individually using reader.read(x)
             where x is small enough."""
         # base implementation just uses the stream method repeatedly
         task = ChannelThreadTask(reader, str(self.stream_async), self.stream)
         return pool.add_task(task)
-    
+
     def size(self):
         """:return: amount of objects in this database"""
         raise NotImplementedError()
-        
+
     def sha_iter(self):
         """Return iterator yielding 20 byte shas for all objects in this data base"""
         raise NotImplementedError()
-            
+
     #} END query interface
-    
-    
+
+
 class ObjectDBW(object):
     """Defines an interface to create objects in the database"""
-    
+
     def __init__(self, *args, **kwargs):
         self._ostream = None
-    
+
     #{ Edit Interface
     def set_ostream(self, stream):
         """
         Adjusts the stream to which all data should be sent when storing new objects
-        
+
         :param stream: if not None, the stream to use, if None the default stream
             will be used.
         :return: previously installed stream, or None if there was no override
@@ -109,96 +112,98 @@ def set_ostream(self, stream):
         cstream = self._ostream
         self._ostream = stream
         return cstream
-        
+
     def ostream(self):
         """
         :return: overridden output stream this instance will write to, or None
             if it will write to the default stream"""
         return self._ostream
-    
+
     def store(self, istream):
         """
         Create a new object in the database
         :return: the input istream object with its sha set to its corresponding value
-        
-        :param istream: IStream compatible instance. If its sha is already set 
-            to a value, the object will just be stored in the our database format, 
+
+        :param istream: IStream compatible instance. If its sha is already set
+            to a value, the object will just be stored in the our database format,
             in which case the input stream is expected to be in object format ( header + contents ).
         :raise IOError: if data could not be written"""
         raise NotImplementedError("To be implemented in subclass")
-    
+
     def store_async(self, reader):
         """
-        Create multiple new objects in the database asynchronously. The method will 
-        return right away, returning an output channel which receives the results as 
+        Create multiple new objects in the database asynchronously. The method will
+        return right away, returning an output channel which receives the results as
         they are computed.
-        
+
         :return: Channel yielding your IStream which served as input, in any order.
-            The IStreams sha will be set to the sha it received during the process, 
+            The IStreams sha will be set to the sha it received during the process,
             or its error attribute will be set to the exception informing about the error.
-            
+
         :param reader: async.Reader yielding IStream instances.
             The same instances will be used in the output channel as were received
             in by the Reader.
-        
-        **Note:** As some ODB implementations implement this operation atomic, they might 
-            abort the whole operation if one item could not be processed. Hence check how 
+
+        **Note:** As some ODB implementations implement this operation atomic, they might
+            abort the whole operation if one item could not be processed. Hence check how
             many items have actually been produced."""
         # base implementation uses store to perform the work
-        task = ChannelThreadTask(reader, str(self.store_async), self.store) 
+        task = ChannelThreadTask(reader, str(self.store_async), self.store)
         return pool.add_task(task)
-    
+
     #} END edit interface
-    
+
 
 class FileDBBase(object):
-    """Provides basic facilities to retrieve files of interest, including 
+    """Provides basic facilities to retrieve files of interest, including
     caching facilities to help mapping hexsha's to objects"""
-    
+
     def __init__(self, root_path):
         """Initialize this instance to look for its files at the given root path
         All subsequent operations will be relative to this path
-        :raise InvalidDBRoot: 
+        :raise InvalidDBRoot:
         **Note:** The base will not perform any accessablity checking as the base
-            might not yet be accessible, but become accessible before the first 
+            might not yet be accessible, but become accessible before the first
             access."""
         super(FileDBBase, self).__init__()
         self._root_path = root_path
-        
-        
-    #{ Interface 
+
+
+    #{ Interface
     def root_path(self):
         """:return: path at which this db operates"""
         return self._root_path
-    
+
     def db_path(self, rela_path):
         """
-        :return: the given relative path relative to our database root, allowing 
+        :return: the given relative path relative to our database root, allowing
             to pontentially access datafiles"""
-        return join(self._root_path, rela_path)
+        from gitdb.utils.encoding import force_text
+
+        return join(self._root_path, force_text(rela_path))
     #} END interface
-        
+
 
 class CachingDB(object):
     """A database which uses caches to speed-up access"""
-    
-    #{ Interface 
+
+    #{ Interface
     def update_cache(self, force=False):
         """
         Call this method if the underlying data changed to trigger an update
         of the internal caching structures.
-        
+
         :param force: if True, the update must be performed. Otherwise the implementation
             may decide not to perform an update if it thinks nothing has changed.
         :return: True if an update was performed as something change indeed"""
-        
+
     # END interface
 
 
 
 
 def _databases_recursive(database, output):
-    """Fill output list with database from db, in order. Deals with Loose, Packed 
+    """Fill output list with database from db, in order. Deals with Loose, Packed
     and compound databases."""
     if isinstance(database, CompoundDB):
         compounds = list()
@@ -209,11 +214,11 @@ def _databases_recursive(database, output):
     else:
         output.append(database)
     # END handle database type
-    
+
 
 class CompoundDB(ObjectDBR, LazyMixin, CachingDB):
     """A database which delegates calls to sub-databases.
-    
+
     Databases are stored in the lazy-loaded _dbs attribute.
     Define _set_cache_ to update it with your databases"""
     def _set_cache_(self, attr):
@@ -223,27 +228,27 @@ def _set_cache_(self, attr):
             self._db_cache = dict()
         else:
             super(CompoundDB, self)._set_cache_(attr)
-    
+
     def _db_query(self, sha):
         """:return: database containing the given 20 byte sha
         :raise BadObject:"""
-        # most databases use binary representations, prevent converting 
+        # most databases use binary representations, prevent converting
         # it everytime a database is being queried
         try:
             return self._db_cache[sha]
         except KeyError:
             pass
         # END first level cache
-        
+
         for db in self._dbs:
             if db.has_object(sha):
                 self._db_cache[sha] = db
                 return db
         # END for each database
         raise BadObject(sha)
-    
-    #{ ObjectDBR interface 
-    
+
+    #{ ObjectDBR interface
+
     def has_object(self, sha):
         try:
             self._db_query(sha)
@@ -251,24 +256,24 @@ def has_object(self, sha):
         except BadObject:
             return False
         # END handle exceptions
-        
+
     def info(self, sha):
         return self._db_query(sha).info(sha)
-        
+
     def stream(self, sha):
         return self._db_query(sha).stream(sha)
 
     def size(self):
         """:return: total size of all contained databases"""
         return reduce(lambda x,y: x+y, (db.size() for db in self._dbs), 0)
-        
+
     def sha_iter(self):
         return chain(*(db.sha_iter() for db in self._dbs))
-        
+
     #} END object DBR Interface
-    
+
     #{ Interface
-    
+
     def databases(self):
         """:return: tuple of database instances we use for lookups"""
         return tuple(self._dbs)
@@ -283,7 +288,7 @@ def update_cache(self, force=False):
             # END if is caching db
         # END for each database to update
         return stat
-        
+
     def partial_to_complete_sha_hex(self, partial_hexsha):
         """
         :return: 20 byte binary sha1 from the given less-than-40 byte hexsha
@@ -291,14 +296,14 @@ def partial_to_complete_sha_hex(self, partial_hexsha):
         :raise AmbiguousObjectName: """
         databases = list()
         _databases_recursive(self, databases)
-        
+
         len_partial_hexsha = len(partial_hexsha)
         if len_partial_hexsha % 2 != 0:
             partial_binsha = hex_to_bin(partial_hexsha + "0")
         else:
             partial_binsha = hex_to_bin(partial_hexsha)
-        # END assure successful binary conversion 
-        
+        # END assure successful binary conversion
+
         candidate = None
         for db in databases:
             full_bin_sha = None
@@ -320,7 +325,5 @@ def partial_to_complete_sha_hex(self, partial_hexsha):
         if not candidate:
             raise BadObject(partial_binsha)
         return candidate
-        
-    #} END interface
-        
 
+    #} END interface
diff --git a/gitdb/db/git.py b/gitdb/db/git.py
index 1d6ad0f..5c74a20 100644
--- a/gitdb/db/git.py
+++ b/gitdb/db/git.py
@@ -2,22 +2,23 @@
 #
 # This module is part of GitDB and is released under
 # the New BSD License: http://www.opensource.org/licenses/bsd-license.php
-from base import (
-                        CompoundDB, 
-                        ObjectDBW, 
-                        FileDBBase
-                    )
+from gitdb.db.base import (
+    CompoundDB,
+    ObjectDBW,
+    FileDBBase
+)
 
-from loose import LooseObjectDB
-from pack import PackedDB
-from ref import ReferenceDB
+from gitdb.db.loose import LooseObjectDB
+from gitdb.db.pack import PackedDB
+from gitdb.db.ref import ReferenceDB
 
 from gitdb.util import LazyMixin
 from gitdb.exc import (
-                        InvalidDBRoot, 
-                        BadObject, 
-                        AmbiguousObjectName
-                        )
+    InvalidDBRoot,
+    BadObject,
+    AmbiguousObjectName
+)
+
 import os
 
 __all__ = ('GitDB', )
@@ -30,21 +31,21 @@ class GitDB(FileDBBase, ObjectDBW, CompoundDB):
     PackDBCls = PackedDB
     LooseDBCls = LooseObjectDB
     ReferenceDBCls = ReferenceDB
-    
+
     # Directories
     packs_dir = 'pack'
     loose_dir = ''
     alternates_dir = os.path.join('info', 'alternates')
-    
+
     def __init__(self, root_path):
         """Initialize ourselves on a git objects directory"""
         super(GitDB, self).__init__(root_path)
-        
+
     def _set_cache_(self, attr):
         if attr == '_dbs' or attr == '_loose_db':
             self._dbs = list()
             loose_db = None
-            for subpath, dbcls in ((self.packs_dir, self.PackDBCls), 
+            for subpath, dbcls in ((self.packs_dir, self.PackDBCls),
                                     (self.loose_dir, self.LooseDBCls),
                                     (self.alternates_dir, self.ReferenceDBCls)):
                 path = self.db_path(subpath)
@@ -55,31 +56,30 @@ def _set_cache_(self, attr):
                     # END remember loose db
                 # END check path exists
             # END for each db type
-            
+
             # should have at least one subdb
             if not self._dbs:
                 raise InvalidDBRoot(self.root_path())
             # END handle error
-            
+
             # we the first one should have the store method
             assert loose_db is not None and hasattr(loose_db, 'store'), "First database needs store functionality"
-            
+
             # finally set the value
             self._loose_db = loose_db
         else:
             super(GitDB, self)._set_cache_(attr)
         # END handle attrs
-        
+
     #{ ObjectDBW interface
-        
+
     def store(self, istream):
         return self._loose_db.store(istream)
-        
+
     def ostream(self):
         return self._loose_db.ostream()
-    
+
     def set_ostream(self, ostream):
         return self._loose_db.set_ostream(ostream)
-        
+
     #} END objectdbw interface
-    
diff --git a/gitdb/db/loose.py b/gitdb/db/loose.py
index dc0ea0e..63f9635 100644
--- a/gitdb/db/loose.py
+++ b/gitdb/db/loose.py
@@ -2,54 +2,57 @@
 #
 # This module is part of GitDB and is released under
 # the New BSD License: http://www.opensource.org/licenses/bsd-license.php
-from base import (
-                        FileDBBase, 
-                        ObjectDBR, 
-                        ObjectDBW
-                )
+from gitdb.db.base import (
+    FileDBBase,
+    ObjectDBR,
+    ObjectDBW
+)
 
 
 from gitdb.exc import (
-    InvalidDBRoot, 
+    InvalidDBRoot,
     BadObject,
     AmbiguousObjectName
-    )
+)
 
 from gitdb.stream import (
-        DecompressMemMapReader,
-        FDCompressedSha1Writer,
-        FDStream,
-        Sha1Writer
-    )
+    DecompressMemMapReader,
+    FDCompressedSha1Writer,
+    FDStream,
+    Sha1Writer
+)
 
 from gitdb.base import (
-                            OStream,
-                            OInfo
-                        )
+    OStream,
+    OInfo
+)
 
 from gitdb.util import (
-        file_contents_ro_filepath,
-        ENOENT,
-        hex_to_bin,
-        bin_to_hex,
-        exists,
-        chmod,
-        isdir,
-        isfile,
-        remove,
-        mkdir,
-        rename,
-        dirname,
-        basename,
-        join
-    )
-
-from gitdb.fun import ( 
+    file_contents_ro_filepath,
+    ENOENT,
+    hex_to_bin,
+    bin_to_hex,
+    exists,
+    chmod,
+    isdir,
+    isfile,
+    remove,
+    mkdir,
+    rename,
+    dirname,
+    basename,
+    join
+)
+
+from gitdb.fun import (
     chunk_size,
-    loose_object_header_info, 
+    loose_object_header_info,
     write_object,
     stream_copy
-    )
+)
+
+from gitdb.utils.compat import MAXSIZE
+from gitdb.utils.encoding import force_bytes
 
 import tempfile
 import mmap
@@ -62,18 +65,18 @@
 
 class LooseObjectDB(FileDBBase, ObjectDBR, ObjectDBW):
     """A database which operates on loose object files"""
-    
+
     # CONFIGURATION
     # chunks in which data will be copied between streams
     stream_chunk_size = chunk_size
-    
+
     # On windows we need to keep it writable, otherwise it cannot be removed
     # either
-    new_objects_mode = 0444
+    new_objects_mode = int("444", 8)
     if os.name == 'nt':
-        new_objects_mode = 0644
-            
-    
+        new_objects_mode = int("644", 8)
+
+
     def __init__(self, root_path):
         super(LooseObjectDB, self).__init__(root_path)
         self._hexsha_to_file = dict()
@@ -81,14 +84,14 @@ def __init__(self, root_path):
         # Depending on the root, this might work for some mounts, for others not, which
         # is why it is per instance
         self._fd_open_flags = getattr(os, 'O_NOATIME', 0)
-    
-    #{ Interface 
+
+    #{ Interface
     def object_path(self, hexsha):
         """
-        :return: path at which the object with the given hexsha would be stored, 
+        :return: path at which the object with the given hexsha would be stored,
             relative to the database root"""
         return join(hexsha[:2], hexsha[2:])
-    
+
     def readable_db_object_path(self, hexsha):
         """
         :return: readable object path to the object identified by hexsha
@@ -97,8 +100,8 @@ def readable_db_object_path(self, hexsha):
             return self._hexsha_to_file[hexsha]
         except KeyError:
             pass
-        # END ignore cache misses 
-            
+        # END ignore cache misses
+
         # try filesystem
         path = self.db_path(self.object_path(hexsha))
         if exists(path):
@@ -106,15 +109,15 @@ def readable_db_object_path(self, hexsha):
             return path
         # END handle cache
         raise BadObject(hexsha)
-        
+
     def partial_to_complete_sha_hex(self, partial_hexsha):
         """:return: 20 byte binary sha1 string which matches the given name uniquely
         :param name: hexadecimal partial name
-        :raise AmbiguousObjectName: 
+        :raise AmbiguousObjectName:
         :raise BadObject: """
         candidate = None
         for binsha in self.sha_iter():
-            if bin_to_hex(binsha).startswith(partial_hexsha):
+            if bin_to_hex(binsha).startswith(force_bytes(partial_hexsha)):
                 # it can't ever find the same object twice
                 if candidate is not None:
                     raise AmbiguousObjectName(partial_hexsha)
@@ -123,9 +126,9 @@ def partial_to_complete_sha_hex(self, partial_hexsha):
         if candidate is None:
             raise BadObject(partial_hexsha)
         return candidate
-        
+
     #} END interface
-    
+
     def _map_loose_object(self, sha):
         """
         :return: memory map of that file to allow random read access
@@ -133,7 +136,7 @@ def _map_loose_object(self, sha):
         db_path = self.db_path(self.object_path(bin_to_hex(sha)))
         try:
             return file_contents_ro_filepath(db_path, flags=self._fd_open_flags)
-        except OSError,e:
+        except OSError as e:
             if e.errno != ENOENT:
                 # try again without noatime
                 try:
@@ -151,27 +154,27 @@ def _map_loose_object(self, sha):
         finally:
             os.close(fd)
         # END assure file is closed
-        
+
     def set_ostream(self, stream):
         """:raise TypeError: if the stream does not support the Sha1Writer interface"""
         if stream is not None and not isinstance(stream, Sha1Writer):
             raise TypeError("Output stream musst support the %s interface" % Sha1Writer.__name__)
         return super(LooseObjectDB, self).set_ostream(stream)
-            
+
     def info(self, sha):
         m = self._map_loose_object(sha)
         try:
-            type, size = loose_object_header_info(m)
-            return OInfo(sha, type, size)
+            typ, size = loose_object_header_info(m)
+            return OInfo(sha, typ, size)
         finally:
             m.close()
         # END assure release of system resources
-        
+
     def stream(self, sha):
         m = self._map_loose_object(sha)
         type, size, stream = DecompressMemMapReader.new(m, close_on_deletion = True)
         return OStream(sha, type, size, stream)
-        
+
     def has_object(self, sha):
         try:
             self.readable_db_object_path(bin_to_hex(sha))
@@ -179,7 +182,7 @@ def has_object(self, sha):
         except BadObject:
             return False
         # END check existance
-    
+
     def store(self, istream):
         """note: The sha we produce will be hex by nature"""
         tmp_path = None
@@ -187,20 +190,20 @@ def store(self, istream):
         if writer is None:
             # open a tmp file to write the data to
             fd, tmp_path = tempfile.mkstemp(prefix='obj', dir=self._root_path)
-            
+
             if istream.binsha is None:
                 writer = FDCompressedSha1Writer(fd)
             else:
                 writer = FDStream(fd)
             # END handle direct stream copies
         # END handle custom writer
-    
+
         try:
             try:
                 if istream.binsha is not None:
                     # copy as much as possible, the actual uncompressed item size might
                     # be smaller than the compressed version
-                    stream_copy(istream.read, writer.write, sys.maxint, self.stream_chunk_size)
+                    stream_copy(istream.read, writer.write, MAXSIZE, self.stream_chunk_size)
                 else:
                     # write object with header, we have to make a new one
                     write_object(istream.type, istream.size, istream.read, writer.write,
@@ -215,14 +218,14 @@ def store(self, istream):
                 os.remove(tmp_path)
             raise
         # END assure tmpfile removal on error
-        
+
         hexsha = None
         if istream.binsha:
             hexsha = istream.hexsha
         else:
             hexsha = writer.sha(as_hex=True)
         # END handle sha
-        
+
         if tmp_path:
             obj_path = self.db_path(self.object_path(hexsha))
             obj_dir = dirname(obj_path)
@@ -234,29 +237,28 @@ def store(self, istream):
                 remove(obj_path)
             # END handle win322
             rename(tmp_path, obj_path)
-            
+
             # make sure its readable for all ! It started out as rw-- tmp file
             # but needs to be rwrr
             chmod(obj_path, self.new_objects_mode)
         # END handle dry_run
-        
+
         istream.binsha = hex_to_bin(hexsha)
         return istream
-        
+
     def sha_iter(self):
         # find all files which look like an object, extract sha from there
         for root, dirs, files in os.walk(self.root_path()):
             root_base = basename(root)
             if len(root_base) != 2:
                 continue
-                
+
             for f in files:
                 if len(f) != 38:
                     continue
                 yield hex_to_bin(root_base + f)
             # END for each file
         # END for each walk iteration
-        
+
     def size(self):
         return len(tuple(self.sha_iter()))
-    
diff --git a/gitdb/db/mem.py b/gitdb/db/mem.py
index b9b2b89..a224546 100644
--- a/gitdb/db/mem.py
+++ b/gitdb/db/mem.py
@@ -3,27 +3,28 @@
 # This module is part of GitDB and is released under
 # the New BSD License: http://www.opensource.org/licenses/bsd-license.php
 """Contains the MemoryDatabase implementation"""
-from loose import LooseObjectDB
-from base import (
-                        ObjectDBR, 
-                        ObjectDBW
-                    )
+from gitdb.db.loose import LooseObjectDB
+from gitdb.db.base import (
+    ObjectDBR,
+    ObjectDBW
+)
 
 from gitdb.base import (
-                            OStream,
-                            IStream,
-                        )
+    OStream,
+    IStream,
+)
 
 from gitdb.exc import (
-                        BadObject,
-                        UnsupportedOperation
-                        )
+    BadObject,
+    UnsupportedOperation
+)
+
 from gitdb.stream import (
-                            ZippedStoreShaWriter,
-                            DecompressMemMapReader,
-                        )
+    ZippedStoreShaWriter,
+    DecompressMemMapReader,
+)
 
-from cStringIO import StringIO
+from io import BytesIO
 
 __all__ = ("MemoryDB", )
 
@@ -32,45 +33,45 @@ class MemoryDB(ObjectDBR, ObjectDBW):
     retrieval. It should be used to buffer results and obtain SHAs before writing
     it to the actual physical storage, as it allows to query whether object already
     exists in the target storage before introducing actual IO
-    
+
     **Note:** memory is currently not threadsafe, hence the async methods cannot be used
         for storing"""
-    
+
     def __init__(self):
         super(MemoryDB, self).__init__()
         self._db = LooseObjectDB("path/doesnt/matter")
-        
+
         # maps 20 byte shas to their OStream objects
         self._cache = dict()
-        
+
     def set_ostream(self, stream):
         raise UnsupportedOperation("MemoryDB's always stream into memory")
-        
+
     def store(self, istream):
         zstream = ZippedStoreShaWriter()
         self._db.set_ostream(zstream)
-        
+
         istream = self._db.store(istream)
         zstream.close()     # close to flush
         zstream.seek(0)
-        
-        # don't provide a size, the stream is written in object format, hence the 
+
+        # don't provide a size, the stream is written in object format, hence the
         # header needs decompression
-        decomp_stream = DecompressMemMapReader(zstream.getvalue(), close_on_deletion=False) 
+        decomp_stream = DecompressMemMapReader(zstream.getvalue(), close_on_deletion=False)
         self._cache[istream.binsha] = OStream(istream.binsha, istream.type, istream.size, decomp_stream)
-        
+
         return istream
-        
+
     def store_async(self, reader):
         raise UnsupportedOperation("MemoryDBs cannot currently be used for async write access")
-    
+
     def has_object(self, sha):
         return sha in self._cache
 
     def info(self, sha):
         # we always return streams, which are infos as well
         return self.stream(sha)
-    
+
     def stream(self, sha):
         try:
             ostream = self._cache[sha]
@@ -80,15 +81,18 @@ def stream(self, sha):
         except KeyError:
             raise BadObject(sha)
         # END exception handling
-    
+
     def size(self):
         return len(self._cache)
-        
+
     def sha_iter(self):
-        return self._cache.iterkeys()
-        
-        
-    #{ Interface 
+        try:
+            return self._cache.iterkeys()
+        except AttributeError:
+            return self._cache.keys()
+
+
+    #{ Interface
     def stream_copy(self, sha_iter, odb):
         """Copy the streams as identified by sha's yielded by sha_iter into the given odb
         The streams will be copied directly
@@ -100,12 +104,12 @@ def stream_copy(self, sha_iter, odb):
             if odb.has_object(sha):
                 continue
             # END check object existance
-            
+
             ostream = self.stream(sha)
             # compressed data including header
-            sio = StringIO(ostream.stream.data())
+            sio = BytesIO(ostream.stream.data())
             istream = IStream(ostream.type, ostream.size, sio, sha)
-            
+
             odb.store(istream)
             count += 1
         # END for each sha
diff --git a/gitdb/db/pack.py b/gitdb/db/pack.py
index 9287319..eca02bb 100644
--- a/gitdb/db/pack.py
+++ b/gitdb/db/pack.py
@@ -3,22 +3,24 @@
 # This module is part of GitDB and is released under
 # the New BSD License: http://www.opensource.org/licenses/bsd-license.php
 """Module containing a database to deal with packs"""
-from base import (
-                        FileDBBase, 
-                        ObjectDBR, 
-                        CachingDB
-                )
+from gitdb.db.base import (
+    FileDBBase,
+    ObjectDBR,
+    CachingDB
+)
 
 from gitdb.util import LazyMixin
 
 from gitdb.exc import (
-                            BadObject,
-                            UnsupportedOperation,
-                            AmbiguousObjectName
-                        )
+    BadObject,
+    UnsupportedOperation,
+    AmbiguousObjectName
+)
 
 from gitdb.pack import PackEntity
 
+from functools import reduce
+
 import os
 import glob
 
@@ -29,12 +31,12 @@
 
 class PackedDB(FileDBBase, ObjectDBR, CachingDB, LazyMixin):
     """A database operating on a set of object packs"""
-    
+
     # sort the priority list every N queries
-    # Higher values are better, performance tests don't show this has 
+    # Higher values are better, performance tests don't show this has
     # any effect, but it should have one
     _sort_interval = 500
-    
+
     def __init__(self, root_path):
         super(PackedDB, self).__init__(root_path)
         # list of lists with three items:
@@ -44,29 +46,29 @@ def __init__(self, root_path):
         # self._entities = list()       # lazy loaded list
         self._hit_count = 0             # amount of hits
         self._st_mtime = 0              # last modification data of our root path
-        
+
     def _set_cache_(self, attr):
         if attr == '_entities':
             self._entities = list()
             self.update_cache(force=True)
         # END handle entities initialization
-        
+
     def _sort_entities(self):
         self._entities.sort(key=lambda l: l[0], reverse=True)
-        
+
     def _pack_info(self, sha):
         """:return: tuple(entity, index) for an item at the given sha
         :param sha: 20 or 40 byte sha
         :raise BadObject:
         **Note:** This method is not thread-safe, but may be hit in multi-threaded
-            operation. The worst thing that can happen though is a counter that 
+            operation. The worst thing that can happen though is a counter that
             was not incremented, or the list being in wrong order. So we safe
             the time for locking here, lets see how that goes"""
         # presort ?
         if self._hit_count % self._sort_interval == 0:
             self._sort_entities()
         # END update sorting
-        
+
         for item in self._entities:
             index = item[2](sha)
             if index is not None:
@@ -75,14 +77,14 @@ def _pack_info(self, sha):
                 return (item[1], index)
             # END index found in pack
         # END for each item
-        
+
         # no hit, see whether we have to update packs
         # NOTE: considering packs don't change very often, we safe this call
         # and leave it to the super-caller to trigger that
         raise BadObject(sha)
-    
-    #{ Object DB Read 
-    
+
+    #{ Object DB Read
+
     def has_object(self, sha):
         try:
             self._pack_info(sha)
@@ -90,68 +92,68 @@ def has_object(self, sha):
         except BadObject:
             return False
         # END exception handling
-        
+
     def info(self, sha):
         entity, index = self._pack_info(sha)
         return entity.info_at_index(index)
-    
+
     def stream(self, sha):
         entity, index = self._pack_info(sha)
         return entity.stream_at_index(index)
-        
+
     def sha_iter(self):
         sha_list = list()
         for entity in self.entities():
             index = entity.index()
             sha_by_index = index.sha
-            for index in xrange(index.size()):
+            for index in range(index.size()):
                 yield sha_by_index(index)
             # END for each index
         # END for each entity
-    
+
     def size(self):
         sizes = [item[1].index().size() for item in self._entities]
         return reduce(lambda x,y: x+y, sizes, 0)
-    
+
     #} END object db read
-    
+
     #{ object db write
-    
+
     def store(self, istream):
-        """Storing individual objects is not feasible as a pack is designed to 
+        """Storing individual objects is not feasible as a pack is designed to
         hold multiple objects. Writing or rewriting packs for single objects is
         inefficient"""
         raise UnsupportedOperation()
-        
+
     def store_async(self, reader):
         # TODO: add ObjectDBRW before implementing this
         raise NotImplementedError()
-    
+
     #} END object db write
-    
-    
-    #{ Interface 
-    
+
+
+    #{ Interface
+
     def update_cache(self, force=False):
         """
-        Update our cache with the acutally existing packs on disk. Add new ones, 
+        Update our cache with the acutally existing packs on disk. Add new ones,
         and remove deleted ones. We keep the unchanged ones
-        
+
         :param force: If True, the cache will be updated even though the directory
             does not appear to have changed according to its modification timestamp.
-        :return: True if the packs have been updated so there is new information, 
+        :return: True if the packs have been updated so there is new information,
             False if there was no change to the pack database"""
         stat = os.stat(self.root_path())
         if not force and stat.st_mtime <= self._st_mtime:
             return False
         # END abort early on no change
         self._st_mtime = stat.st_mtime
-        
+
         # packs are supposed to be prefixed with pack- by git-convention
         # get all pack files, figure out what changed
         pack_files = set(glob.glob(os.path.join(self.root_path(), "pack-*.pack")))
         our_pack_files = set(item[1].pack().path() for item in self._entities)
-        
+
         # new packs
         for pack_file in (pack_files - our_pack_files):
             # init the hit-counter/priority with the size, a good measure for hit-
@@ -159,7 +161,7 @@ def update_cache(self, force=False):
             entity = PackEntity(pack_file)
             self._entities.append([entity.pack().size(), entity, entity.index().sha_to_index])
         # END for each new packfile
-        
+
         # removed packs
         for pack_file in (our_pack_files - pack_files):
             del_index = -1
@@ -172,22 +174,22 @@ def update_cache(self, force=False):
             assert del_index != -1
             del(self._entities[del_index])
         # END for each removed pack
-        
+
         # reinitialize prioritiess
         self._sort_entities()
         return True
-        
+
     def entities(self):
         """:return: list of pack entities operated upon by this database"""
         return [ item[1] for item in self._entities ]
-        
+
     def partial_to_complete_sha(self, partial_binsha, canonical_length):
         """:return: 20 byte sha as inferred by the given partial binary sha
-        :param partial_binsha: binary sha with less than 20 bytes 
+        :param partial_binsha: binary sha with less than 20 bytes
         :param canonical_length: length of the corresponding canonical representation.
             It is required as binary sha's cannot display whether the original hex sha
             had an odd or even number of characters
-        :raise AmbiguousObjectName: 
+        :raise AmbiguousObjectName:
         :raise BadObject: """
         candidate = None
         for item in self._entities:
@@ -199,11 +201,11 @@ def partial_to_complete_sha(self, partial_binsha, canonical_length):
                 candidate = sha
             # END handle full sha could be found
         # END for each entity
-        
+
         if candidate:
             return candidate
-        
+
         # still not found ?
         raise BadObject(partial_binsha)
-    
+
     #} END interface
diff --git a/gitdb/db/ref.py b/gitdb/db/ref.py
index 60004a7..748f7c1 100644
--- a/gitdb/db/ref.py
+++ b/gitdb/db/ref.py
@@ -2,25 +2,25 @@
 #
 # This module is part of GitDB and is released under
 # the New BSD License: http://www.opensource.org/licenses/bsd-license.php
-from base import (
-                    CompoundDB,
-                )
+from gitdb.db.base import (
+    CompoundDB,
+)
 
 import os
 __all__ = ('ReferenceDB', )
 
 class ReferenceDB(CompoundDB):
     """A database consisting of database referred to in a file"""
-    
+
     # Configuration
     # Specifies the object database to use for the paths found in the alternates
     # file. If None, it defaults to the GitDB
     ObjectDBCls = None
-    
+
     def __init__(self, ref_file):
         super(ReferenceDB, self).__init__()
         self._ref_file = ref_file
-        
+
     def _set_cache_(self, attr):
         if attr == '_dbs':
             self._dbs = list()
@@ -28,15 +28,15 @@ def _set_cache_(self, attr):
         else:
             super(ReferenceDB, self)._set_cache_(attr)
         # END handle attrs
-        
+
     def _update_dbs_from_ref_file(self):
         dbcls = self.ObjectDBCls
         if dbcls is None:
             # late import
-            from git import GitDB
+            from gitdb.db.git import GitDB
             dbcls = GitDB
         # END get db type
-        
+
         # try to get as many as possible, don't fail if some are unavailable
         ref_paths = list()
         try:
@@ -44,10 +44,10 @@ def _update_dbs_from_ref_file(self):
         except (OSError, IOError):
             pass
         # END handle alternates
-        
+
         ref_paths_set = set(ref_paths)
         cur_ref_paths_set = set(db.root_path() for db in self._dbs)
-        
+
         # remove existing
         for path in (cur_ref_paths_set - ref_paths_set):
             for i, db in enumerate(self._dbs[:]):
@@ -56,7 +56,7 @@ def _update_dbs_from_ref_file(self):
                     continue
                 # END del matching db
         # END for each path to remove
-        
+
         # add new
         # sort them to maintain order
         added_paths = sorted(ref_paths_set - cur_ref_paths_set, key=lambda p: ref_paths.index(p))
@@ -68,11 +68,11 @@ def _update_dbs_from_ref_file(self):
                     db.databases()
                 # END verification
                 self._dbs.append(db)
-            except Exception, e:
+            except Exception:
                 # ignore invalid paths or issues
                 pass
         # END for each path to add
-        
+
     def update_cache(self, force=False):
         # re-read alternates and update databases
         self._update_dbs_from_ref_file()
diff --git a/gitdb/exc.py b/gitdb/exc.py
index 7180fb5..73f84d2 100644
--- a/gitdb/exc.py
+++ b/gitdb/exc.py
@@ -3,21 +3,21 @@
 # This module is part of GitDB and is released under
 # the New BSD License: http://www.opensource.org/licenses/bsd-license.php
 """Module with common exceptions"""
-from util import to_hex_sha
+from gitdb.util import to_hex_sha
 
 class ODBError(Exception):
     """All errors thrown by the object database"""
-    
+
 class InvalidDBRoot(ODBError):
     """Thrown if an object database cannot be initialized at the given path"""
-    
+
 class BadObject(ODBError):
-    """The object with the given SHA does not exist. Instantiate with the 
+    """The object with the given SHA does not exist. Instantiate with the
     failed sha"""
-    
+
     def __str__(self):
         return "BadObject: %s" % to_hex_sha(self.args[0])
-        
+
 class ParseError(ODBError):
     """Thrown if the parsing of a file failed due to an invalid format"""
 
diff --git a/gitdb/ext/async b/gitdb/ext/async
index 90326fb..3f26b05 160000
--- a/gitdb/ext/async
+++ b/gitdb/ext/async
@@ -1 +1 @@
-Subproject commit 90326fb867f94b193c277b07b23e364047e1ed28
+Subproject commit 3f26b05c2f1a079d5807ed15c01b053ee846e745
diff --git a/gitdb/ext/smmap b/gitdb/ext/smmap
index 616e9ce..5526711 160000
--- a/gitdb/ext/smmap
+++ b/gitdb/ext/smmap
@@ -1 +1 @@
-Subproject commit 616e9ceaf917e4d8f3cf2c145401b8069ce307dd
+Subproject commit 55267119140f3828a24b4986600ed21a1808d6cc
diff --git a/gitdb/fun.py b/gitdb/fun.py
index c1e73e8..6495359 100644
--- a/gitdb/fun.py
+++ b/gitdb/fun.py
@@ -6,17 +6,25 @@
 Keeping this code separate from the beginning makes it easier to out-source
 it into c later, if required"""
 
-from exc import (
+from gitdb.exc import (
     BadObjectType
-    )
+)
 
-from util import zlib
+from gitdb.util import byte_ord, zlib
 decompressobj = zlib.decompressobj
 
 import mmap
-from itertools import islice, izip
+from itertools import islice
 
-from cStringIO import StringIO
+from gitdb.utils.compat import izip
+from gitdb.typ import (
+    str_blob_type,
+    str_commit_type,
+    str_tree_type,
+    str_tag_type,
+)
+
+from io import StringIO
 
 # INVARIANTS
 OFS_DELTA = 6
@@ -24,30 +32,30 @@
 delta_types = (OFS_DELTA, REF_DELTA)
 
 type_id_to_type_map =   {
-                            0 : "",             # EXT 1
-                            1 : "commit",
-                            2 : "tree",
-                            3 : "blob",
-                            4 : "tag",
-                            5 : "",             # EXT 2
-                            OFS_DELTA : "OFS_DELTA",    # OFFSET DELTA
-                            REF_DELTA : "REF_DELTA"     # REFERENCE DELTA
-                        }
-
-type_to_type_id_map = dict(
-                            commit=1, 
-                            tree=2,
-                            blob=3,
-                            tag=4,
-                            OFS_DELTA=OFS_DELTA,
-                            REF_DELTA=REF_DELTA
-                        )
+    0 : "",             # EXT 1
+    1 : str_commit_type,
+    2 : str_tree_type,
+    3 : str_blob_type,
+    4 : str_tag_type,
+    5 : "",             # EXT 2
+    OFS_DELTA : "OFS_DELTA",    # OFFSET DELTA
+    REF_DELTA : "REF_DELTA"     # REFERENCE DELTA
+}
+
+type_to_type_id_map = {
+    str_commit_type: 1,
+    str_tree_type: 2,
+    str_blob_type: 3,
+    str_tag_type: 4,
+    "OFS_DELTA": OFS_DELTA,
+    "REF_DELTA": REF_DELTA,
+}
 
 # used when dealing with larger streams
-chunk_size = 1000*mmap.PAGESIZE
+chunk_size = 1000 * mmap.PAGESIZE
 
-__all__ = ('is_loose_object', 'loose_object_header_info', 'msb_size', 'pack_object_header_info', 
-            'write_object', 'loose_object_header', 'stream_copy', 'apply_delta_data', 
+__all__ = ('is_loose_object', 'loose_object_header_info', 'msb_size', 'pack_object_header_info',
+            'write_object', 'loose_object_header', 'stream_copy', 'apply_delta_data',
             'is_equal_canonical_sha', 'connect_deltas', 'DeltaChunkList', 'create_pack_object_header')
 
 
@@ -59,11 +67,11 @@ def _set_delta_rbound(d, size):
         to our size
     :return: d"""
     d.ts = size
-    
+
     # NOTE: data is truncated automatically when applying the delta
     # MUST NOT DO THIS HERE
     return d
-            
+
 def _move_delta_lbound(d, bytes):
     """Move the delta by the given amount of bytes, reducing its size so that its
     right bound stays static
@@ -71,19 +79,19 @@ def _move_delta_lbound(d, bytes):
     :return: d"""
     if bytes == 0:
         return
-        
+
     d.to += bytes
     d.so += bytes
     d.ts -= bytes
     if d.data is not None:
         d.data = d.data[bytes:]
     # END handle data
-    
+
     return d
-    
+
 def delta_duplicate(src):
     return DeltaChunk(src.to, src.ts, src.so, src.data)
-    
+
 def delta_chunk_apply(dc, bbuf, write):
     """Apply own data to the target buffer
     :param bbuf: buffer providing source bytes for copy operations
@@ -107,13 +115,13 @@ class DeltaChunk(object):
     """Represents a piece of a delta, it can either add new data, or copy existing
     one from a source buffer"""
     __slots__ = (
-                    'to',       # start offset in the target buffer in bytes 
+                    'to',       # start offset in the target buffer in bytes
                     'ts',       # size of this chunk in the target buffer in bytes
                     'so',       # start offset in the source buffer in bytes or None
                     'data',     # chunk of bytes to be added to the target buffer,
                                 # DeltaChunkList to use as base, or None
                 )
-    
+
     def __init__(self, to, ts, so, data):
         self.to = to
         self.ts = ts
@@ -122,22 +130,22 @@ def __init__(self, to, ts, so, data):
 
     def __repr__(self):
         return "DeltaChunk(%i, %i, %s, %s)" % (self.to, self.ts, self.so, self.data or "")
-    
+
     #{ Interface
-        
+
     def rbound(self):
         return self.to + self.ts
-        
+
     def has_data(self):
         """:return: True if the instance has data to add to the target stream"""
         return self.data is not None
-        
+
     #} END interface
 
 def _closest_index(dcl, absofs):
     """:return: index at which the given absofs should be inserted. The index points
     to the DeltaChunk with a target buffer absofs that equals or is greater than
-    absofs. 
+    absofs.
     **Note:** global method for performance only, it belongs to DeltaChunkList"""
     lo = 0
     hi = len(dcl)
@@ -153,7 +161,7 @@ def _closest_index(dcl, absofs):
         # END handle bound
     # END for each delta absofs
     return len(dcl)-1
-    
+
 def delta_list_apply(dcl, bbuf, write):
     """Apply the chain's changes and write the final result using the passed
     write function.
@@ -166,14 +174,14 @@ def delta_list_apply(dcl, bbuf, write):
     # END for each dc
 
 def delta_list_slice(dcl, absofs, size, ndcl):
-    """:return: Subsection of this  list at the given absolute  offset, with the given 
+    """:return: Subsection of this  list at the given absolute  offset, with the given
         size in bytes.
     :return: None"""
     cdi = _closest_index(dcl, absofs)   # delta start index
     cd = dcl[cdi]
     slen = len(dcl)
-    lappend = ndcl.append 
-    
+    lappend = ndcl.append
+
     if cd.to != absofs:
         tcd = DeltaChunk(cd.to, cd.ts, cd.so, cd.data)
         _move_delta_lbound(tcd, absofs - cd.to)
@@ -182,7 +190,7 @@ def delta_list_slice(dcl, absofs, size, ndcl):
         size -= tcd.ts
         cdi += 1
     # END lbound overlap handling
-    
+
     while cdi < slen and size:
         # are we larger than the current block
         cd = dcl[cdi]
@@ -198,38 +206,38 @@ def delta_list_slice(dcl, absofs, size, ndcl):
         # END hadle size
         cdi += 1
     # END for each chunk
-    
-    
+
+
 class DeltaChunkList(list):
     """List with special functionality to deal with DeltaChunks.
     There are two types of lists we represent. The one was created bottom-up, working
-    towards the latest delta, the other kind was created top-down, working from the 
-    latest delta down to the earliest ancestor. This attribute is queryable 
+    towards the latest delta, the other kind was created top-down, working from the
+    latest delta down to the earliest ancestor. This attribute is queryable
     after all processing with is_reversed."""
-    
+
     __slots__ = tuple()
-    
+
     def rbound(self):
         """:return: rightmost extend in bytes, absolute"""
         if len(self) == 0:
             return 0
         return self[-1].rbound()
-        
+
     def lbound(self):
         """:return: leftmost byte at which this chunklist starts"""
         if len(self) == 0:
             return 0
         return self[0].to
-        
+
     def size(self):
         """:return: size of bytes as measured by our delta chunks"""
         return self.rbound() - self.lbound()
-        
+
     def apply(self, bbuf, write):
         """Only used by public clients, internally we only use the global routines
         for performance"""
         return delta_list_apply(self, bbuf, write)
-        
+
     def compress(self):
         """Alter the list to reduce the amount of nodes. Currently we concatenate
         add-chunks
@@ -239,7 +247,7 @@ def compress(self):
             return self
         i = 0
         slen_orig = slen
-        
+
         first_data_index = None
         while i < slen:
             dc = self[i]
@@ -253,27 +261,27 @@ def compress(self):
                         xdc = self[x]
                         nd.write(xdc.data[:xdc.ts])
                     # END collect data
-                    
+
                     del(self[first_data_index:i-1])
                     buf = nd.getvalue()
-                    self.insert(first_data_index, DeltaChunk(so, len(buf), 0, buf)) 
-                    
+                    self.insert(first_data_index, DeltaChunk(so, len(buf), 0, buf))
+
                     slen = len(self)
                     i = first_data_index + 1
-                    
+
                 # END concatenate data
                 first_data_index = None
                 continue
             # END skip non-data chunks
-            
+
             if first_data_index is None:
                 first_data_index = i-1
         # END iterate list
-        
+
         #if slen_orig != len(self):
         #   print "INFO: Reduced delta list len to %f %% of former size" % ((float(len(self)) / slen_orig) * 100)
         return self
-        
+
     def check_integrity(self, target_size=-1):
         """Verify the list has non-overlapping chunks only, and the total size matches
         target_size
@@ -283,39 +291,39 @@ def check_integrity(self, target_size=-1):
             assert self[-1].rbound() == target_size
             assert reduce(lambda x,y: x+y, (d.ts for d in self), 0) == target_size
         # END target size verification
-        
+
         if len(self) < 2:
             return
-            
+
         # check data
         for dc in self:
             assert dc.ts > 0
             if dc.has_data():
                 assert len(dc.data) >= dc.ts
         # END for each dc
-            
+
         left = islice(self, 0, len(self)-1)
         right = iter(self)
         right.next()
-        # this is very pythonic - we might have just use index based access here, 
+        # this is very pythonic - we might have just use index based access here,
         # but this could actually be faster
         for lft,rgt in izip(left, right):
             assert lft.rbound() == rgt.to
             assert lft.to + lft.ts == rgt.to
         # END for each pair
-        
+
 
 class TopdownDeltaChunkList(DeltaChunkList):
-    """Represents a list which is generated by feeding its ancestor streams one by 
+    """Represents a list which is generated by feeding its ancestor streams one by
     one"""
-    __slots__ = tuple() 
-    
+    __slots__ = tuple()
+
     def connect_with_next_base(self, bdcl):
         """Connect this chain with the next level of our base delta chunklist.
         The goal in this game is to mark as many of our chunks rigid, hence they
-        cannot be changed by any of the upcoming bases anymore. Once all our 
+        cannot be changed by any of the upcoming bases anymore. Once all our
         chunks are marked like that, we can stop all processing
-        :param bdcl: data chunk list being one of our bases. They must be fed in 
+        :param bdcl: data chunk list being one of our bases. They must be fed in
             consequtively and in order, towards the earliest ancestor delta
         :return: True if processing was done. Use it to abort processing of
             remaining streams if False is returned"""
@@ -326,13 +334,13 @@ def connect_with_next_base(self, bdcl):
         while dci < slen:
             dc = self[dci]
             dci += 1
-            
+
             # all add-chunks which are already topmost don't need additional processing
             if dc.data is not None:
                 nfc += 1
                 continue
             # END skip add chunks
-            
+
             # copy chunks
             # integrate the portion of the base list into ourselves. Lists
             # dont support efficient insertion ( just one at a time ), but for now
@@ -341,13 +349,13 @@ def connect_with_next_base(self, bdcl):
             # ourselves in order to reduce the amount of insertions ...
             del(ccl[:])
             delta_list_slice(bdcl, dc.so, dc.ts, ccl)
-            
+
             # move the target bounds into place to match with our chunk
             ofs = dc.to - dc.so
             for cdc in ccl:
                 cdc.to += ofs
             # END update target bounds
-            
+
             if len(ccl) == 1:
                 self[dci-1] = ccl[0]
             else:
@@ -359,19 +367,19 @@ def connect_with_next_base(self, bdcl):
                 del(self[dci-1:])           # include deletion of dc
                 self.extend(ccl)
                 self.extend(post_dci)
-                
+
                 slen = len(self)
                 dci += len(ccl)-1           # deleted dc, added rest
-                
+
             # END handle chunk replacement
         # END for each chunk
-        
+
         if nfc == slen:
             return False
         # END handle completeness
         return True
-        
-        
+
+
 #} END structures
 
 #{ Routines
@@ -386,27 +394,31 @@ def is_loose_object(m):
 
 def loose_object_header_info(m):
     """
-    :return: tuple(type_string, uncompressed_size_in_bytes) the type string of the 
+    :return: tuple(type_string, uncompressed_size_in_bytes) the type string of the
         object as well as its uncompressed size in bytes.
     :param m: memory map from which to read the compressed object data"""
+    from gitdb.const import NULL_BYTE
+    from gitdb.utils.encoding import force_text
+
     decompress_size = 8192      # is used in cgit as well
     hdr = decompressobj().decompress(m, decompress_size)
-    type_name, size = hdr[:hdr.find("\0")].split(" ")
+    type_name, size = hdr[:hdr.find(NULL_BYTE)].split(" ".encode("ascii"))
+
     return type_name, int(size)
-    
+
 def pack_object_header_info(data):
     """
     :return: tuple(type_id, uncompressed_size_in_bytes, byte_offset)
         The type_id should be interpreted according to the ``type_id_to_type_map`` map
         The byte-offset specifies the start of the actual zlib compressed datastream
     :param m: random-access memory, like a string or memory map"""
-    c = ord(data[0])                # first byte
+    c = byte_ord(data[0])           # first byte
     i = 1                           # next char to read
     type_id = (c >> 4) & 7          # numeric type
     size = c & 15                   # starting size
     s = 4                           # starting bit-shift size
     while c & 0x80:
-        c = ord(data[i])
+        c = byte_ord(data[i])
         i += 1
         size += (c & 0x7f) << s
         s += 7
@@ -417,7 +429,7 @@ def create_pack_object_header(obj_type, obj_size):
     """
     :return: string defining the pack header comprised of the object type
         and its incompressed size in bytes
-    
+
     :param obj_type: pack type_id of the object
     :param obj_size: uncompressed size in bytes of the following object stream"""
     c = 0       # 1 byte
@@ -432,17 +444,17 @@ def create_pack_object_header(obj_type, obj_size):
     #END until size is consumed
     hdr += chr(c)
     return hdr
-    
+
 def msb_size(data, offset=0):
     """
-    :return: tuple(read_bytes, size) read the msb size from the given random 
+    :return: tuple(read_bytes, size) read the msb size from the given random
         access data starting at the given byte offset"""
     size = 0
     i = 0
     l = len(data)
     hit_msb = False
     while i < l:
-        c = ord(data[i+offset])
+        c = byte_ord(data[i+offset])
         size |= (c & 0x7f) << i*7
         i += 1
         if not c & 0x80:
@@ -452,19 +464,19 @@ def msb_size(data, offset=0):
     # END while in range
     if not hit_msb:
         raise AssertionError("Could not find terminating MSB byte in data stream")
-    return i+offset, size 
-    
+    return i+offset, size
+
 def loose_object_header(type, size):
     """
     :return: string representing the loose object header, which is immediately
         followed by the content stream of size 'size'"""
     return "%s %i\0" % (type, size)
-        
+
 def write_object(type, size, read, write, chunk_size=chunk_size):
     """
-    Write the object as identified by type, size and source_stream into the 
+    Write the object as identified by type, size and source_stream into the
     target_stream
-    
+
     :param type: type string of the object
     :param size: amount of bytes to write from source_stream
     :param read: read method of a stream providing the content data
@@ -473,26 +485,26 @@ def write_object(type, size, read, write, chunk_size=chunk_size):
         the routine exits, even if an error is thrown
     :return: The actual amount of bytes written to stream, which includes the header and a trailing newline"""
     tbw = 0                                             # total num bytes written
-    
+
     # WRITE HEADER: type SP size NULL
     tbw += write(loose_object_header(type, size))
     tbw += stream_copy(read, write, size, chunk_size)
-    
+
     return tbw
 
 def stream_copy(read, write, size, chunk_size):
     """
-    Copy a stream up to size bytes using the provided read and write methods, 
+    Copy a stream up to size bytes using the provided read and write methods,
     in chunks of chunk_size
-    
+
     **Note:** its much like stream_copy utility, but operates just using methods"""
     dbw = 0                                             # num data bytes written
-    
+
     # WRITE ALL DATA UP TO SIZE
     while True:
         cs = min(chunk_size, size-dbw)
         # NOTE: not all write methods return the amount of written bytes, like
-        # mmap.write. Its bad, but we just deal with it ... perhaps its not 
+        # mmap.write. Its bad, but we just deal with it ... perhaps its not
         # even less efficient
         # data_len = write(read(cs))
         # dbw += data_len
@@ -505,27 +517,27 @@ def stream_copy(read, write, size, chunk_size):
         # END check for stream end
     # END duplicate data
     return dbw
-    
+
 def connect_deltas(dstreams):
     """
     Read the condensed delta chunk information from dstream and merge its information
         into a list of existing delta chunks
-    
+
     :param dstreams: iterable of delta stream objects, the delta to be applied last
         comes first, then all its ancestors in order
     :return: DeltaChunkList, containing all operations to apply"""
     tdcl = None                         # topmost dcl
-    
+
     dcl = tdcl = TopdownDeltaChunkList()
     for dsi, ds in enumerate(dstreams):
         # print "Stream", dsi
         db = ds.read()
         delta_buf_size = ds.size
-        
+
         # read header
         i, base_size = msb_size(db)
         i, target_size = msb_size(db, i)
-        
+
         # interpret opcodes
         tbw = 0                     # amount of target bytes written
         while i < delta_buf_size:
@@ -554,15 +566,15 @@ def connect_deltas(dstreams):
                 if (c & 0x40):
                     cp_size |= (ord(db[i]) << 16)
                     i += 1
-                    
-                if not cp_size: 
+
+                if not cp_size:
                     cp_size = 0x10000
-                
+
                 rbound = cp_off + cp_size
                 if (rbound < cp_size or
                     rbound > base_size):
                     break
-                
+
                 dcl.append(DeltaChunk(tbw, cp_size, cp_off, None))
                 tbw += cp_size
             elif c:
@@ -575,31 +587,31 @@ def connect_deltas(dstreams):
                 raise ValueError("unexpected delta opcode 0")
             # END handle command byte
         # END while processing delta data
-        
+
         dcl.compress()
-        
+
         # merge the lists !
         if dsi > 0:
             if not tdcl.connect_with_next_base(dcl):
                 break
         # END handle merge
-        
+
         # prepare next base
         dcl = DeltaChunkList()
     # END for each delta stream
-    
+
     return tdcl
-    
+
 def apply_delta_data(src_buf, src_buf_size, delta_buf, delta_buf_size, write):
     """
     Apply data from a delta buffer using a source buffer to the target file
-    
+
     :param src_buf: random access data from which the delta was created
     :param src_buf_size: size of the source buffer in bytes
     :param delta_buf_size: size fo the delta buffer in bytes
     :param delta_buf: random access delta data
     :param write: write method taking a chunk of bytes
-    
+
     **Note:** transcribed to python from the similar routine in patch-delta.c"""
     i = 0
     db = delta_buf
@@ -629,10 +641,10 @@ def apply_delta_data(src_buf, src_buf_size, delta_buf, delta_buf_size, write):
             if (c & 0x40):
                 cp_size |= (ord(db[i]) << 16)
                 i += 1
-                
-            if not cp_size: 
+
+            if not cp_size:
                 cp_size = 0x10000
-            
+
             rbound = cp_off + cp_size
             if (rbound < cp_size or
                 rbound > src_buf_size):
@@ -645,28 +657,28 @@ def apply_delta_data(src_buf, src_buf_size, delta_buf, delta_buf_size, write):
             raise ValueError("unexpected delta opcode 0")
         # END handle command byte
     # END while processing delta data
-    
+
     # yes, lets use the exact same error message that git uses :)
     assert i == delta_buf_size, "delta replay has gone wild"
-    
-    
+
+
 def is_equal_canonical_sha(canonical_length, match, sha1):
     """
     :return: True if the given lhs and rhs 20 byte binary shas
-        The comparison will take the canonical_length of the match sha into account, 
+        The comparison will take the canonical_length of the match sha into account,
         hence the comparison will only use the last 4 bytes for uneven canonical representations
     :param match: less than 20 byte sha
     :param sha1: 20 byte sha"""
-    binary_length = canonical_length/2
+    binary_length = canonical_length // 2
     if match[:binary_length] != sha1[:binary_length]:
         return False
-        
+
     if canonical_length - binary_length and \
-        (ord(match[-1]) ^ ord(sha1[len(match)-1])) & 0xf0:
+        (byte_ord(match[-1]) ^ byte_ord(sha1[len(match)-1])) & 0xf0:
         return False
     # END handle uneven canonnical length
     return True
-    
+
 #} END routines
 
 
diff --git a/gitdb/pack.py b/gitdb/pack.py
index 48121f0..4e83ba3 100644
--- a/gitdb/pack.py
+++ b/gitdb/pack.py
@@ -4,31 +4,33 @@
 # the New BSD License: http://www.opensource.org/licenses/bsd-license.php
 """Contains PackIndexFile and PackFile implementations"""
 from gitdb.exc import (
-                        BadObject,
-                        UnsupportedOperation,
-                        ParseError
-                        )
-from util import (
-                    zlib,
-                    mman,
-                    LazyMixin,
-                    unpack_from,
-                    bin_to_hex,
-                    )
+    BadObject,
+    UnsupportedOperation,
+    ParseError
+)
+
+from gitdb.util import (
+    zlib,
+    mman,
+    LazyMixin,
+    unpack_from,
+    bin_to_hex,
+    byte_ord,
+)
 
-from fun import (
-                    create_pack_object_header,
-                    pack_object_header_info,
-                    is_equal_canonical_sha,
-                    type_id_to_type_map,
-                    write_object,
-                    stream_copy, 
-                    chunk_size,
-                    delta_types,
-                    OFS_DELTA, 
-                    REF_DELTA,
-                    msb_size
-                )
+from gitdb.fun import (
+    create_pack_object_header,
+    pack_object_header_info,
+    is_equal_canonical_sha,
+    type_id_to_type_map,
+    write_object,
+    stream_copy,
+    chunk_size,
+    delta_types,
+    OFS_DELTA,
+    REF_DELTA,
+    msb_size
+)
 
 try:
     from _perf import PackIndexFile_sha_to_index
@@ -36,31 +38,34 @@
     pass
 # END try c module
 
-from base import (      # Amazing !
-                        OInfo,
-                        OStream,
-                        OPackInfo,
-                        OPackStream,
-                        ODeltaStream,
-                        ODeltaPackInfo,
-                        ODeltaPackStream,
-                    )
-from stream import (
-                        DecompressMemMapReader,
-                        DeltaApplyReader,
-                        Sha1Writer,
-                        NullStream,
-                        FlexibleSha1Writer
-                    )
+from gitdb.base import (      # Amazing !
+    OInfo,
+    OStream,
+    OPackInfo,
+    OPackStream,
+    ODeltaStream,
+    ODeltaPackInfo,
+    ODeltaPackStream,
+)
+
+from gitdb.stream import (
+    DecompressMemMapReader,
+    DeltaApplyReader,
+    Sha1Writer,
+    NullStream,
+    FlexibleSha1Writer
+)
 
 from struct import (
-                        pack,
-                        unpack,
-                    )
+    pack,
+    unpack,
+)
 
 from binascii import crc32
 
-from itertools import izip
+from gitdb.const import NULL_BYTE
+from gitdb.utils.compat import izip, buffer
+
 import tempfile
 import array
 import os
@@ -68,10 +73,10 @@
 
 __all__ = ('PackIndexFile', 'PackFile', 'PackEntity')
 
- 
 
-    
-#{ Utilities 
+
+
+#{ Utilities
 
 def pack_object_at(cursor, offset, as_stream):
     """
@@ -81,13 +86,15 @@ def pack_object_at(cursor, offset, as_stream):
         data to be read decompressed.
     :param data: random accessable data containing all required information
     :parma offset: offset in to the data at which the object information is located
-    :param as_stream: if True, a stream object will be returned that can read 
+    :param as_stream: if True, a stream object will be returned that can read
         the data, otherwise you receive an info object only"""
+    from gitdb.utils.encoding import force_bytes
+
     data = cursor.use_region(offset).buffer()
     type_id, uncomp_size, data_rela_offset = pack_object_header_info(data)
     total_rela_offset = None                # set later, actual offset until data stream begins
     delta_info = None
-    
+
     # OFFSET DELTA
     if type_id == OFS_DELTA:
         i = data_rela_offset
@@ -111,13 +118,14 @@ def pack_object_at(cursor, offset, as_stream):
         # assume its a base object
         total_rela_offset = data_rela_offset
     # END handle type id
-    
     abs_data_offset = offset + total_rela_offset
     if as_stream:
-        stream = DecompressMemMapReader(buffer(data, total_rela_offset), False, uncomp_size)
+        buff = buffer(data, total_rela_offset)
+        stream = DecompressMemMapReader(buff, False, uncomp_size)
         if delta_info is None:
             return abs_data_offset, OPackStream(offset, type_id, uncomp_size, stream)
         else:
+            delta_info = force_bytes(delta_info)
             return abs_data_offset, ODeltaPackStream(offset, type_id, uncomp_size, delta_info, stream)
     else:
         if delta_info is None:
@@ -141,29 +149,29 @@ def write_stream_to_pack(read, write, zstream, base_crc=None):
     if want_crc:
         crc = base_crc
     #END initialize crc
-    
+
     while True:
         chunk = read(chunk_size)
         br += len(chunk)
         compressed = zstream.compress(chunk)
         bw += len(compressed)
         write(compressed)           # cannot assume return value
-        
+
         if want_crc:
             crc = crc32(compressed, crc)
         #END handle crc
-        
+
         if len(chunk) != chunk_size:
             break
     #END copy loop
-    
+
     compressed = zstream.flush()
     bw += len(compressed)
     write(compressed)
     if want_crc:
         crc = crc32(compressed, crc)
     #END handle crc
-    
+
     return (br, bw, crc)
 
 
@@ -175,47 +183,47 @@ class IndexWriter(object):
     in one go to the given stream
     **Note:** currently only writes v2 indices"""
     __slots__ = '_objs'
-    
+
     def __init__(self):
         self._objs = list()
-        
+
     def append(self, binsha, crc, offset):
         """Append one piece of object information"""
         self._objs.append((binsha, crc, offset))
-        
+
     def write(self, pack_sha, write):
         """Write the index file using the given write method
         :param pack_sha: binary sha over the whole pack that we index
         :return: sha1 binary sha over all index file contents"""
         # sort for sha1 hash
         self._objs.sort(key=lambda o: o[0])
-        
+
         sha_writer = FlexibleSha1Writer(write)
         sha_write = sha_writer.write
         sha_write(PackIndexFile.index_v2_signature)
         sha_write(pack(">L", PackIndexFile.index_version_default))
-        
+
         # fanout
         tmplist = list((0,)*256)                                # fanout or list with 64 bit offsets
         for t in self._objs:
             tmplist[ord(t[0][0])] += 1
         #END prepare fanout
-        for i in xrange(255):
+        for i in range(255):
             v = tmplist[i]
             sha_write(pack('>L', v))
             tmplist[i+1] += v
         #END write each fanout entry
         sha_write(pack('>L', tmplist[255]))
-        
+
         # sha1 ordered
         # save calls, that is push them into c
         sha_write(''.join(t[0] for t in self._objs))
-        
+
         # crc32
         for t in self._objs:
             sha_write(pack('>L', t[1]&0xffffffff))
         #END for each crc
-        
+
         tmplist = list()
         # offset 32
         for t in self._objs:
@@ -226,28 +234,28 @@ def write(self, pack_sha, write):
             #END hande 64 bit offsets
             sha_write(pack('>L', ofs&0xffffffff))
         #END for each offset
-        
+
         # offset 64
         for ofs in tmplist:
             sha_write(pack(">Q", ofs))
         #END for each offset
-        
+
         # trailer
         assert(len(pack_sha) == 20)
         sha_write(pack_sha)
         sha = sha_writer.sha(as_hex=False)
         write(sha)
         return sha
-        
-    
+
+
 
 class PackIndexFile(LazyMixin):
     """A pack index provides offsets into the corresponding pack, allowing to find
     locations for offsets faster."""
-    
+
     # Dont use slots as we dynamically bind functions for each version, need a dict for this
     # The slots you see here are just to keep track of our instance variables
-    # __slots__ = ('_indexpath', '_fanout_table', '_cursor', '_version', 
+    # __slots__ = ('_indexpath', '_fanout_table', '_cursor', '_version',
     #               '_sha_list_offset', '_crc_list_offset', '_pack_offset', '_pack_64_offset')
 
     # used in v2 indices
@@ -258,7 +266,7 @@ class PackIndexFile(LazyMixin):
     def __init__(self, indexpath):
         super(PackIndexFile, self).__init__()
         self._indexpath = indexpath
-    
+
     def _set_cache_(self, attr):
         if attr == "_packfile_checksum":
             self._packfile_checksum = self._cursor.map()[-40:-20]
@@ -276,91 +284,91 @@ def _set_cache_(self, attr):
         else:
             # now its time to initialize everything - if we are here, someone wants
             # to access the fanout table or related properties
-            
+
             # CHECK VERSION
             mmap = self._cursor.map()
             self._version = (mmap[:4] == self.index_v2_signature and 2) or 1
             if self._version == 2:
-                version_id = unpack_from(">L", mmap, 4)[0] 
+                version_id = unpack_from(">L", mmap, 4)[0]
                 assert version_id == self._version, "Unsupported index version: %i" % version_id
             # END assert version
-            
+
             # SETUP FUNCTIONS
             # setup our functions according to the actual version
             for fname in ('entry', 'offset', 'sha', 'crc'):
                 setattr(self, fname, getattr(self, "_%s_v%i" % (fname, self._version)))
             # END for each function to initialize
-            
-            
+
+
             # INITIALIZE DATA
             # byte offset is 8 if version is 2, 0 otherwise
             self._initialize()
         # END handle attributes
-        
+
 
     #{ Access V1
-    
+
     def _entry_v1(self, i):
         """:return: tuple(offset, binsha, 0)"""
-        return unpack_from(">L20s", self._cursor.map(), 1024 + i*24) + (0, ) 
-    
+        return unpack_from(">L20s", self._cursor.map(), 1024 + i*24) + (0, )
+
     def _offset_v1(self, i):
         """see ``_offset_v2``"""
         return unpack_from(">L", self._cursor.map(), 1024 + i*24)[0]
-    
+
     def _sha_v1(self, i):
         """see ``_sha_v2``"""
         base = 1024 + (i*24)+4
         return self._cursor.map()[base:base+20]
-        
+
     def _crc_v1(self, i):
         """unsupported"""
         return 0
-        
+
     #} END access V1
-    
+
     #{ Access V2
     def _entry_v2(self, i):
         """:return: tuple(offset, binsha, crc)"""
         return (self._offset_v2(i), self._sha_v2(i), self._crc_v2(i))
-    
+
     def _offset_v2(self, i):
-        """:return: 32 or 64 byte offset into pack files. 64 byte offsets will only 
+        """:return: 32 or 64 byte offset into pack files. 64 byte offsets will only
             be returned if the pack is larger than 4 GiB, or 2^32"""
         offset = unpack_from(">L", self._cursor.map(), self._pack_offset + i * 4)[0]
-        
+
         # if the high-bit is set, this indicates that we have to lookup the offset
         # in the 64 bit region of the file. The current offset ( lower 31 bits )
         # are the index into it
         if offset & 0x80000000:
             offset = unpack_from(">Q", self._cursor.map(), self._pack_64_offset + (offset & ~0x80000000) * 8)[0]
         # END handle 64 bit offset
-        
+
         return offset
-        
+
     def _sha_v2(self, i):
         """:return: sha at the given index of this file index instance"""
         base = self._sha_list_offset + i * 20
         return self._cursor.map()[base:base+20]
-        
+
     def _crc_v2(self, i):
         """:return: 4 bytes crc for the object at index i"""
-        return unpack_from(">L", self._cursor.map(), self._crc_list_offset + i * 4)[0] 
-        
+        return unpack_from(">L", self._cursor.map(), self._crc_list_offset + i * 4)[0]
+
     #} END access V2
-    
+
     #{ Initialization
-    
+
     def _initialize(self):
         """initialize base data"""
         self._fanout_table = self._read_fanout((self._version == 2) * 8)
-        
+
         if self._version == 2:
             self._crc_list_offset = self._sha_list_offset + self.size() * 20
             self._pack_offset = self._crc_list_offset + self.size() * 4
             self._pack_64_offset = self._pack_offset + self.size() * 4
         # END setup base
-        
+
     def _read_fanout(self, byte_offset):
         """Generate a fanout table from our data"""
         d = self._cursor.map()
@@ -370,100 +378,101 @@ def _read_fanout(self, byte_offset):
             append(unpack_from('>L', d, byte_offset + i*4)[0])
         # END for each entry
         return out
-    
+
     #} END initialization
-        
+
     #{ Properties
     def version(self):
         return self._version
-        
+
     def size(self):
         """:return: amount of objects referred to by this index"""
         return self._fanout_table[255]
-        
+
     def path(self):
         """:return: path to the packindexfile"""
         return self._indexpath
-        
+
     def packfile_checksum(self):
         """:return: 20 byte sha representing the sha1 hash of the pack file"""
         return self._cursor.map()[-40:-20]
-        
+
     def indexfile_checksum(self):
         """:return: 20 byte sha representing the sha1 hash of this index file"""
         return self._cursor.map()[-20:]
-        
+
     def offsets(self):
         """:return: sequence of all offsets in the order in which they were written
-        
+
         **Note:** return value can be random accessed, but may be immmutable"""
         if self._version == 2:
             # read stream to array, convert to tuple
             a = array.array('I')    # 4 byte unsigned int, long are 8 byte on 64 bit it appears
             a.fromstring(buffer(self._cursor.map(), self._pack_offset, self._pack_64_offset - self._pack_offset))
-            
+
             # networkbyteorder to something array likes more
             if sys.byteorder == 'little':
                 a.byteswap()
             return a
         else:
-            return tuple(self.offset(index) for index in xrange(self.size()))
+            return tuple(self.offset(index) for index in range(self.size()))
         # END handle version
-        
+
     def sha_to_index(self, sha):
         """
         :return: index usable with the ``offset`` or ``entry`` method, or None
             if the sha was not found in this pack index
         :param sha: 20 byte sha to lookup"""
-        first_byte = ord(sha[0])
+        first_byte = byte_ord(sha[0])
         get_sha = self.sha
         lo = 0                  # lower index, the left bound of the bisection
         if first_byte != 0:
             lo = self._fanout_table[first_byte-1]
         hi = self._fanout_table[first_byte]     # the upper, right bound of the bisection
-        
+
         # bisect until we have the sha
         while lo < hi:
-            mid = (lo + hi) / 2
-            c = cmp(sha, get_sha(mid))
-            if c < 0:
+            mid = (lo + hi) // 2
+            mid_sha = get_sha(mid)
+            if sha < mid_sha:
                 hi = mid
-            elif not c:
+            elif sha == mid_sha:
                 return mid
             else:
                 lo = mid + 1
             # END handle midpoint
         # END bisect
         return None
-        
+
     def partial_sha_to_index(self, partial_bin_sha, canonical_length):
         """
         :return: index as in `sha_to_index` or None if the sha was not found in this
             index file
         :param partial_bin_sha: an at least two bytes of a partial binary sha
-        :param canonical_length: lenght of the original hexadecimal representation of the 
+        :param canonical_length: lenght of the original hexadecimal representation of the
             given partial binary sha
         :raise AmbiguousObjectName:"""
         if len(partial_bin_sha) < 2:
             raise ValueError("Require at least 2 bytes of partial sha")
-        
-        first_byte = ord(partial_bin_sha[0])
+
+        first_byte = byte_ord(partial_bin_sha[0])
+
         get_sha = self.sha
         lo = 0                  # lower index, the left bound of the bisection
         if first_byte != 0:
             lo = self._fanout_table[first_byte-1]
         hi = self._fanout_table[first_byte]     # the upper, right bound of the bisection
-        
+
         # fill the partial to full 20 bytes
-        filled_sha = partial_bin_sha + '\0'*(20 - len(partial_bin_sha))
-        
-        # find lowest 
+        filled_sha = partial_bin_sha + NULL_BYTE * (20 - len(partial_bin_sha))
+
+        # find lowest
         while lo < hi:
-            mid = (lo + hi) / 2
-            c = cmp(filled_sha, get_sha(mid))
-            if c < 0:
+            mid = (lo + hi) // 2
+            mid_sha = get_sha(mid)
+            if filled_sha < mid_sha:
                 hi = mid
-            elif not c:
+            elif filled_sha == mid_sha:
                 # perfect match
                 lo = mid
                 break
@@ -471,12 +480,12 @@ def partial_sha_to_index(self, partial_bin_sha, canonical_length):
                 lo = mid + 1
             # END handle midpoint
         # END bisect
-        
+
         if lo < self.size():
             cur_sha = get_sha(lo)
             if is_equal_canonical_sha(canonical_length, partial_bin_sha, cur_sha):
                 next_sha = None
-                if lo+1 < self.size():
+                if lo + 1 < self.size():
                     next_sha = get_sha(lo+1)
                 if next_sha and next_sha == cur_sha:
                     raise AmbiguousObjectName(partial_bin_sha)
@@ -484,86 +493,86 @@ def partial_sha_to_index(self, partial_bin_sha, canonical_length):
             # END if we have a match
         # END if we found something
         return None
-        
+
     if 'PackIndexFile_sha_to_index' in globals():
-        # NOTE: Its just about 25% faster, the major bottleneck might be the attr 
+        # NOTE: Its just about 25% faster, the major bottleneck might be the attr
         # accesses
         def sha_to_index(self, sha):
             return PackIndexFile_sha_to_index(self, sha)
-    # END redefine heavy-hitter with c version  
-    
+    # END redefine heavy-hitter with c version
+
     #} END properties
-    
-    
+
+
 class PackFile(LazyMixin):
     """A pack is a file written according to the Version 2 for git packs
-    
+
     As we currently use memory maps, it could be assumed that the maximum size of
-    packs therefor is 32 bit on 32 bit systems. On 64 bit systems, this should be 
+    packs therefor is 32 bit on 32 bit systems. On 64 bit systems, this should be
     fine though.
-    
-    **Note:** at some point, this might be implemented using streams as well, or 
+
+    **Note:** at some point, this might be implemented using streams as well, or
     streams are an alternate path in the case memory maps cannot be created
-    for some reason - one clearly doesn't want to read 10GB at once in that 
+    for some reason - one clearly doesn't want to read 10GB at once in that
     case"""
-    
+
     __slots__ = ('_packpath', '_cursor', '_size', '_version')
     pack_signature = 0x5041434b     # 'PACK'
     pack_version_default = 2
-    
+
     # offset into our data at which the first object starts
     first_object_offset = 3*4       # header bytes
     footer_size = 20                # final sha
-    
+
     def __init__(self, packpath):
         self._packpath = packpath
-        
+
     def _set_cache_(self, attr):
         # we fill the whole cache, whichever attribute gets queried first
         self._cursor = mman.make_cursor(self._packpath).use_region()
-        
+
         # read the header information
         type_id, self._version, self._size = unpack_from(">LLL", self._cursor.map(), 0)
-            
+
         # TODO: figure out whether we should better keep the lock, or maybe
         # add a .keep file instead ?
         if type_id != self.pack_signature:
             raise ParseError("Invalid pack signature: %i" % type_id)
-        
+
     def _iter_objects(self, start_offset, as_stream=True):
         """Handle the actual iteration of objects within this pack"""
         c = self._cursor
         content_size = c.file_size() - self.footer_size
         cur_offset = start_offset or self.first_object_offset
-        
+
         null = NullStream()
         while cur_offset < content_size:
             data_offset, ostream = pack_object_at(c, cur_offset, True)
             # scrub the stream to the end - this decompresses the object, but yields
             # the amount of compressed bytes we need to get to the next offset
-                
+
             stream_copy(ostream.read, null.write, ostream.size, chunk_size)
             cur_offset += (data_offset - ostream.pack_offset) + ostream.stream.compressed_bytes_read()
-            
-            
+
+
             # if a stream is requested, reset it beforehand
-            # Otherwise return the Stream object directly, its derived from the 
+            # Otherwise return the Stream object directly, its derived from the
             # info object
             if as_stream:
                 ostream.stream.seek(0)
             yield ostream
         # END until we have read everything
-        
+
     #{ Pack Information
-    
+
     def size(self):
-        """:return: The amount of objects stored in this pack""" 
+        """:return: The amount of objects stored in this pack"""
         return self._size
-        
+
     def version(self):
         """:return: the version of this pack"""
         return self._version
-        
+
     def data(self):
         """
         :return: read-only data of this pack. It provides random access and usually
@@ -571,22 +580,22 @@ def data(self):
         :note: This method is unsafe as it returns a window into a file which might be larger than than the actual window size"""
         # can use map as we are starting at offset 0. Otherwise we would have to use buffer()
         return self._cursor.use_region().map()
-        
+
     def checksum(self):
         """:return: 20 byte sha1 hash on all object sha's contained in this file"""
         return self._cursor.use_region(self._cursor.file_size()-20).buffer()[:]
-    
+
     def path(self):
         """:return: path to the packfile"""
         return self._packpath
     #} END pack information
-    
+
     #{ Pack Specific
-    
+
     def collect_streams(self, offset):
         """
         :return: list of pack streams which are required to build the object
-            at the given offset. The first entry of the list is the object at offset, 
+            at the given offset. The first entry of the list is the object at offset,
             the last one is either a full object, or a REF_Delta stream. The latter
             type needs its reference object to be locked up in an ODB to form a valid
             delta chain.
@@ -601,7 +610,7 @@ def collect_streams(self, offset):
                 offset = ostream.pack_offset - ostream.delta_info
             else:
                 # the only thing we can lookup are OFFSET deltas. Everything
-                # else is either an object, or a ref delta, in the latter 
+                # else is either an object, or a ref delta, in the latter
                 # case someone else has to find it
                 break
             # END handle type
@@ -609,55 +618,55 @@ def collect_streams(self, offset):
         return out
 
     #} END pack specific
-    
+
     #{ Read-Database like Interface
-    
+
     def info(self, offset):
         """Retrieve information about the object at the given file-absolute offset
-        
+
         :param offset: byte offset
         :return: OPackInfo instance, the actual type differs depending on the type_id attribute"""
         return pack_object_at(self._cursor, offset or self.first_object_offset, False)[1]
-        
+
     def stream(self, offset):
         """Retrieve an object at the given file-relative offset as stream along with its information
-        
+
         :param offset: byte offset
         :return: OPackStream instance, the actual type differs depending on the type_id attribute"""
         return pack_object_at(self._cursor, offset or self.first_object_offset, True)[1]
-        
+
     def stream_iter(self, start_offset=0):
         """
-        :return: iterator yielding OPackStream compatible instances, allowing 
+        :return: iterator yielding OPackStream compatible instances, allowing
             to access the data in the pack directly.
-        :param start_offset: offset to the first object to iterate. If 0, iteration 
+        :param start_offset: offset to the first object to iterate. If 0, iteration
             starts at the very first object in the pack.
-            
+
         **Note:** Iterating a pack directly is costly as the datastream has to be decompressed
         to determine the bounds between the objects"""
         return self._iter_objects(start_offset, as_stream=True)
-        
+
     #} END Read-Database like Interface
-    
-    
+
+
 class PackEntity(LazyMixin):
-    """Combines the PackIndexFile and the PackFile into one, allowing the 
+    """Combines the PackIndexFile and the PackFile into one, allowing the
     actual objects to be resolved and iterated"""
-    
-    __slots__ = (   '_index',           # our index file 
+
+    __slots__ = (   '_index',           # our index file
                     '_pack',            # our pack file
                     '_offset_map'       # on demand dict mapping one offset to the next consecutive one
                     )
-    
+
     IndexFileCls = PackIndexFile
     PackFileCls = PackFile
-    
+
     def __init__(self, pack_or_index_path):
         """Initialize ourselves with the path to the respective pack or index file"""
         basename, ext = os.path.splitext(pack_or_index_path)
         self._index = self.IndexFileCls("%s.idx" % basename)            # PackIndexFile instance
         self._pack = self.PackFileCls("%s.pack" % basename)         # corresponding PackFile instance
-        
+
     def _set_cache_(self, attr):
         # currently this can only be _offset_map
         # TODO: make this a simple sorted offset array which can be bisected
@@ -666,7 +675,7 @@ def _set_cache_(self, attr):
         offsets_sorted = sorted(self._index.offsets())
         last_offset = len(self._pack.data()) - self._pack.footer_size
         assert offsets_sorted, "Cannot handle empty indices"
-        
+
         offset_map = None
         if len(offsets_sorted) == 1:
             offset_map = { offsets_sorted[0] : last_offset }
@@ -675,29 +684,29 @@ def _set_cache_(self, attr):
             iter_offsets_plus_one = iter(offsets_sorted)
             iter_offsets_plus_one.next()
             consecutive = izip(iter_offsets, iter_offsets_plus_one)
-            
+
             offset_map = dict(consecutive)
-            
+
             # the last offset is not yet set
             offset_map[offsets_sorted[-1]] = last_offset
         # END handle offset amount
         self._offset_map = offset_map
-    
+
     def _sha_to_index(self, sha):
         """:return: index for the given sha, or raise"""
         index = self._index.sha_to_index(sha)
         if index is None:
             raise BadObject(sha)
         return index
-    
+
     def _iter_objects(self, as_stream):
         """Iterate over all objects in our index and yield their OInfo or OStream instences"""
         _sha = self._index.sha
         _object = self._object
-        for index in xrange(self._index.size()):
+        for index in range(self._index.size()):
             yield _object(_sha(index), as_stream, index)
         # END for each index
-    
+
     def _object(self, sha, as_stream, index=-1):
         """:return: OInfo or OStream object providing information about the given sha
         :param index: if not -1, its assumed to be the sha's index in the IndexFile"""
@@ -714,86 +723,86 @@ def _object(self, sha, as_stream, index=-1):
                 packstream = self._pack.stream(offset)
                 return OStream(sha, packstream.type, packstream.size, packstream.stream)
             # END handle non-deltas
-            
+
             # produce a delta stream containing all info
-            # To prevent it from applying the deltas when querying the size, 
+            # To prevent it from applying the deltas when querying the size,
             # we extract it from the delta stream ourselves
             streams = self.collect_streams_at_offset(offset)
             dstream = DeltaApplyReader.new(streams)
-            
-            return ODeltaStream(sha, dstream.type, None, dstream) 
+
+            return ODeltaStream(sha, dstream.type, None, dstream)
         else:
             if type_id not in delta_types:
                 return OInfo(sha, type_id_to_type_map[type_id], uncomp_size)
             # END handle non-deltas
-            
+
             # deltas are a little tougher - unpack the first bytes to obtain
             # the actual target size, as opposed to the size of the delta data
             streams = self.collect_streams_at_offset(offset)
             buf = streams[0].read(512)
             offset, src_size = msb_size(buf)
             offset, target_size = msb_size(buf, offset)
-            
+
             # collect the streams to obtain the actual object type
             if streams[-1].type_id in delta_types:
                 raise BadObject(sha, "Could not resolve delta object")
-            return OInfo(sha, streams[-1].type, target_size) 
+            return OInfo(sha, streams[-1].type, target_size)
         # END handle stream
-    
+
     #{ Read-Database like Interface
-    
+
     def info(self, sha):
         """Retrieve information about the object identified by the given sha
-        
+
         :param sha: 20 byte sha1
         :raise BadObject:
         :return: OInfo instance, with 20 byte sha"""
         return self._object(sha, False)
-        
+
     def stream(self, sha):
         """Retrieve an object stream along with its information as identified by the given sha
-        
+
         :param sha: 20 byte sha1
-        :raise BadObject: 
+        :raise BadObject:
         :return: OStream instance, with 20 byte sha"""
         return self._object(sha, True)
 
     def info_at_index(self, index):
         """As ``info``, but uses a PackIndexFile compatible index to refer to the object"""
         return self._object(None, False, index)
-    
+
     def stream_at_index(self, index):
-        """As ``stream``, but uses a PackIndexFile compatible index to refer to the 
+        """As ``stream``, but uses a PackIndexFile compatible index to refer to the
         object"""
         return self._object(None, True, index)
-        
+
     #} END Read-Database like Interface
-    
-    #{ Interface 
+
+    #{ Interface
 
     def pack(self):
         """:return: the underlying pack file instance"""
         return self._pack
-        
+
     def index(self):
         """:return: the underlying pack index file instance"""
         return self._index
-        
+
     def is_valid_stream(self, sha, use_crc=False):
         """
         Verify that the stream at the given sha is valid.
-        
-        :param use_crc: if True, the index' crc is run over the compressed stream of 
+
+        :param use_crc: if True, the index' crc is run over the compressed stream of
             the object, which is much faster than checking the sha1. It is also
             more prone to unnoticed corruption or manipulation.
         :param sha: 20 byte sha1 of the object whose stream to verify
-            whether the compressed stream of the object is valid. If it is 
-            a delta, this only verifies that the delta's data is valid, not the 
-            data of the actual undeltified object, as it depends on more than 
+            whether the compressed stream of the object is valid. If it is
+            a delta, this only verifies that the delta's data is valid, not the
+            data of the actual undeltified object, as it depends on more than
             just this stream.
             If False, the object will be decompressed and the sha generated. It must
             match the given sha
-            
+
         :return: True if the stream is valid
         :raise UnsupportedOperation: If the index is version 1 only
         :raise BadObject: sha was not found"""
@@ -801,12 +810,12 @@ def is_valid_stream(self, sha, use_crc=False):
             if self._index.version() < 2:
                 raise UnsupportedOperation("Version 1 indices do not contain crc's, verify by sha instead")
             # END handle index version
-            
+
             index = self._sha_to_index(sha)
             offset = self._index.offset(index)
             next_offset = self._offset_map[offset]
             crc_value = self._index.crc(index)
-            
+
             # create the current crc value, on the compressed object data
             # Read it in chunks, without copying the data
             crc_update = zlib.crc32
@@ -819,7 +828,7 @@ def is_valid_stream(self, sha, use_crc=False):
                 this_crc_value = crc_update(buffer(pack_data, cur_pos, size), this_crc_value)
                 cur_pos += size
             # END window size loop
-            
+
             # crc returns signed 32 bit numbers, the AND op forces it into unsigned
             # mode ... wow, sneaky, from dulwich.
             return (this_crc_value & 0xffffffff) == crc_value
@@ -828,7 +837,7 @@ def is_valid_stream(self, sha, use_crc=False):
             stream = self._object(sha, as_stream=True)
             # write a loose object, which is the basis for the sha
             write_object(stream.type, stream.size, stream.read, shawriter.write)
-            
+
             assert shawriter.sha(as_hex=False) == sha
             return shawriter.sha(as_hex=False) == sha
         # END handle crc/sha verification
@@ -839,21 +848,21 @@ def info_iter(self):
         :return: Iterator over all objects in this pack. The iterator yields
             OInfo instances"""
         return self._iter_objects(as_stream=False)
-        
+
     def stream_iter(self):
         """
         :return: iterator over all objects in this pack. The iterator yields
             OStream instances"""
         return self._iter_objects(as_stream=True)
-        
+
     def collect_streams_at_offset(self, offset):
         """
         As the version in the PackFile, but can resolve REF deltas within this pack
         For more info, see ``collect_streams``
-        
+
         :param offset: offset into the pack file at which the object can be found"""
         streams = self._pack.collect_streams(offset)
-        
+
         # try to resolve the last one if needed. It is assumed to be either
         # a REF delta, or a base object, as OFFSET deltas are resolved by the pack
         if streams[-1].type_id == REF_DELTA:
@@ -866,54 +875,54 @@ def collect_streams_at_offset(self, offset):
                     stream = self._pack.stream(self._index.offset(sindex))
                     streams.append(stream)
                 else:
-                    # must be another OFS DELTA - this could happen if a REF 
-                    # delta we resolve previously points to an OFS delta. Who 
+                    # must be another OFS DELTA - this could happen if a REF
+                    # delta we resolve previously points to an OFS delta. Who
                     # would do that ;) ? We can handle it though
                     stream = self._pack.stream(stream.delta_info)
                     streams.append(stream)
                 # END handle ref delta
             # END resolve ref streams
         # END resolve streams
-        
+
         return streams
-        
+
     def collect_streams(self, sha):
         """
         As ``PackFile.collect_streams``, but takes a sha instead of an offset.
         Additionally, ref_delta streams will be resolved within this pack.
         If this is not possible, the stream will be left alone, hence it is adivsed
-        to check for unresolved ref-deltas and resolve them before attempting to 
+        to check for unresolved ref-deltas and resolve them before attempting to
         construct a delta stream.
-        
+
         :param sha: 20 byte sha1 specifying the object whose related streams you want to collect
-        :return: list of streams, first being the actual object delta, the last being 
+        :return: list of streams, first being the actual object delta, the last being
             a possibly unresolved base object.
         :raise BadObject:"""
         return self.collect_streams_at_offset(self._index.offset(self._sha_to_index(sha)))
-        
-        
+
+
     @classmethod
-    def write_pack(cls, object_iter, pack_write, index_write=None, 
+    def write_pack(cls, object_iter, pack_write, index_write=None,
                     object_count = None, zlib_compression = zlib.Z_BEST_SPEED):
         """
         Create a new pack by putting all objects obtained by the object_iterator
         into a pack which is written using the pack_write method.
         The respective index is produced as well if index_write is not Non.
-        
+
         :param object_iter: iterator yielding odb output objects
         :param pack_write: function to receive strings to write into the pack stream
         :param indx_write: if not None, the function writes the index file corresponding
             to the pack.
-        :param object_count: if you can provide the amount of objects in your iteration, 
-            this would be the place to put it. Otherwise we have to pre-iterate and store 
+        :param object_count: if you can provide the amount of objects in your iteration,
+            this would be the place to put it. Otherwise we have to pre-iterate and store
             all items into a list to get the number, which uses more memory than necessary.
         :param zlib_compression: the zlib compression level to use
         :return: tuple(pack_sha, index_binsha) binary sha over all the contents of the pack
             and over all contents of the index. If index_write was None, index_binsha will be None
-            
+
         **Note:** The destination of the write functions is up to the user. It could
         be a socket, or a file for instance
-        
+
         **Note:** writes only undeltified objects"""
         objs = object_iter
         if not object_count:
@@ -922,26 +931,26 @@ def write_pack(cls, object_iter, pack_write, index_write=None,
             #END handle list type
             object_count = len(objs)
         #END handle object
-        
+
         pack_writer = FlexibleSha1Writer(pack_write)
         pwrite = pack_writer.write
         ofs = 0                                         # current offset into the pack file
         index = None
         wants_index = index_write is not None
-        
+
         # write header
         pwrite(pack('>LLL', PackFile.pack_signature, PackFile.pack_version_default, object_count))
         ofs += 12
-        
+
         if wants_index:
             index = IndexWriter()
         #END handle index header
-        
+
         actual_count = 0
         for obj in objs:
             actual_count += 1
             crc = 0
-            
+
             # object header
             hdr = create_pack_object_header(obj.type_id, obj.size)
             if index_write:
@@ -950,7 +959,7 @@ def write_pack(cls, object_iter, pack_write, index_write=None,
                 crc = None
             #END handle crc
             pwrite(hdr)
-            
+
             # data stream
             zstream = zlib.compressobj(zlib_compression)
             ostream = obj.stream
@@ -959,54 +968,54 @@ def write_pack(cls, object_iter, pack_write, index_write=None,
             if wants_index:
                 index.append(obj.binsha, crc, ofs)
             #END handle index
-            
+
             ofs += len(hdr) + bw
             if actual_count == object_count:
                 break
             #END abort once we are done
         #END for each object
-        
+
         if actual_count != object_count:
             raise ValueError("Expected to write %i objects into pack, but received only %i from iterators" % (object_count, actual_count))
         #END count assertion
-        
+
         # write footer
         pack_sha = pack_writer.sha(as_hex = False)
         assert len(pack_sha) == 20
         pack_write(pack_sha)
         ofs += len(pack_sha)                            # just for completeness ;)
-        
+
         index_sha = None
         if wants_index:
             index_sha = index.write(pack_sha, index_write)
         #END handle index
-        
+
         return pack_sha, index_sha
-    
+
     @classmethod
     def create(cls, object_iter, base_dir, object_count = None, zlib_compression = zlib.Z_BEST_SPEED):
         """Create a new on-disk entity comprised of a properly named pack file and a properly named
         and corresponding index file. The pack contains all OStream objects contained in object iter.
         :param base_dir: directory which is to contain the files
         :return: PackEntity instance initialized with the new pack
-        
+
         **Note:** for more information on the other parameters see the write_pack method"""
         pack_fd, pack_path = tempfile.mkstemp('', 'pack', base_dir)
         index_fd, index_path = tempfile.mkstemp('', 'index', base_dir)
         pack_write = lambda d: os.write(pack_fd, d)
         index_write = lambda d: os.write(index_fd, d)
-        
+
         pack_binsha, index_binsha = cls.write_pack(object_iter, pack_write, index_write, object_count, zlib_compression)
         os.close(pack_fd)
         os.close(index_fd)
-        
+
         fmt = "pack-%s.%s"
         new_pack_path = os.path.join(base_dir, fmt % (bin_to_hex(pack_binsha), 'pack'))
         new_index_path = os.path.join(base_dir, fmt % (bin_to_hex(pack_binsha), 'idx'))
         os.rename(pack_path, new_pack_path)
         os.rename(index_path, new_index_path)
-        
+
         return cls(new_pack_path)
-        
-        
+
+
     #} END interface
diff --git a/gitdb/stream.py b/gitdb/stream.py
index 6441b1e..5dd38ec 100644
--- a/gitdb/stream.py
+++ b/gitdb/stream.py
@@ -3,28 +3,33 @@
 # This module is part of GitDB and is released under
 # the New BSD License: http://www.opensource.org/licenses/bsd-license.php
 
-from cStringIO import StringIO
+from io import BytesIO, StringIO
+
 import errno
 import mmap
 import os
 
-from fun import (
-                    msb_size,
-                    stream_copy, 
-                    apply_delta_data,
-                    connect_deltas,
-                    DeltaChunkList,
-                    delta_types
-                )
-
-from util import (
-        allocate_memory,
-        LazyMixin,
-        make_sha,
-        write, 
-        close,
-        zlib
-    )
+from gitdb.fun import (
+    msb_size,
+    stream_copy,
+    apply_delta_data,
+    connect_deltas,
+    DeltaChunkList,
+    delta_types
+)
+
+from gitdb.util import (
+    allocate_memory,
+    LazyMixin,
+    make_sha,
+    write,
+    close,
+    zlib
+)
+
+from gitdb.const import NULL_BYTE
+from gitdb.utils.compat import buffer
+from gitdb.utils.encoding import force_bytes
 
 has_perf_mod = False
 try:
@@ -33,7 +38,7 @@
 except ImportError:
     pass
 
-__all__ = ( 'DecompressMemMapReader', 'FDCompressedSha1Writer', 'DeltaApplyReader', 
+__all__ = ( 'DecompressMemMapReader', 'FDCompressedSha1Writer', 'DeltaApplyReader',
             'Sha1Writer', 'FlexibleSha1Writer', 'ZippedStoreShaWriter', 'FDCompressedSha1Writer',
             'FDStream', 'NullStream')
 
@@ -41,27 +46,27 @@
 #{ RO Streams
 
 class DecompressMemMapReader(LazyMixin):
-    """Reads data in chunks from a memory map and decompresses it. The client sees 
+    """Reads data in chunks from a memory map and decompresses it. The client sees
     only the uncompressed data, respective file-like read calls are handling on-demand
     buffered decompression accordingly
-    
-    A constraint on the total size of bytes is activated, simulating 
+
+    A constraint on the total size of bytes is activated, simulating
     a logical file within a possibly larger physical memory area
-    
-    To read efficiently, you clearly don't want to read individual bytes, instead, 
+
+    To read efficiently, you clearly don't want to read individual bytes, instead,
     read a few kilobytes at least.
-    
-    **Note:** The chunk-size should be carefully selected as it will involve quite a bit 
-        of string copying due to the way the zlib is implemented. Its very wasteful, 
-        hence we try to find a good tradeoff between allocation time and number of 
+
+    **Note:** The chunk-size should be carefully selected as it will involve quite a bit
+        of string copying due to the way the zlib is implemented. Its very wasteful,
+        hence we try to find a good tradeoff between allocation time and number of
         times we actually allocate. An own zlib implementation would be good here
         to better support streamed reading - it would only need to keep the mmap
         and decompress it into chunks, thats all ... """
-    __slots__ = ('_m', '_zip', '_buf', '_buflen', '_br', '_cws', '_cwe', '_s', '_close', 
+    __slots__ = ('_m', '_zip', '_buf', '_buflen', '_br', '_cws', '_cwe', '_s', '_close',
                 '_cbr', '_phi')
-    
+
     max_read_size = 512*1024        # currently unused
-    
+
     def __init__(self, m, close_on_deletion, size=None):
         """Initialize with mmap for stream reading
         :param m: must be content data - use new if you have object data and no size"""
@@ -77,84 +82,84 @@ def __init__(self, m, close_on_deletion, size=None):
         self._cbr = 0                           # number of compressed bytes read
         self._phi = False                       # is True if we parsed the header info
         self._close = close_on_deletion         # close the memmap on deletion ?
-        
+
     def _set_cache_(self, attr):
         assert attr == '_s'
-        # only happens for size, which is a marker to indicate we still 
+        # only happens for size, which is a marker to indicate we still
         # have to parse the header from the stream
         self._parse_header_info()
-        
+
     def __del__(self):
         if self._close:
             self._m.close()
         # END handle resource freeing
-        
+
     def _parse_header_info(self):
-        """If this stream contains object data, parse the header info and skip the 
+        """If this stream contains object data, parse the header info and skip the
         stream to a point where each read will yield object content
-        
+
         :return: parsed type_string, size"""
         # read header
         maxb = 512              # should really be enough, cgit uses 8192 I believe
         self._s = maxb
         hdr = self.read(maxb)
-        hdrend = hdr.find("\0")
-        type, size = hdr[:hdrend].split(" ")
+        hdrend = hdr.find(NULL_BYTE)
+        typ, size = hdr[:hdrend].split(" ".encode("ascii"))
         size = int(size)
         self._s = size
-        
+
         # adjust internal state to match actual header length that we ignore
         # The buffer will be depleted first on future reads
         self._br = 0
-        hdrend += 1                                 # count terminating \0
-        self._buf = StringIO(hdr[hdrend:])
+        hdrend += 1
+        self._buf = BytesIO(hdr[hdrend:])
         self._buflen = len(hdr) - hdrend
-        
+
         self._phi = True
-        
-        return type, size
-        
-    #{ Interface 
-    
+
+        return typ, size
+
+    #{ Interface
+
     @classmethod
     def new(self, m, close_on_deletion=False):
         """Create a new DecompressMemMapReader instance for acting as a read-only stream
-        This method parses the object header from m and returns the parsed 
+        This method parses the object header from m and returns the parsed
         type and size, as well as the created stream instance.
-        
+
         :param m: memory map on which to oparate. It must be object data ( header + contents )
-        :param close_on_deletion: if True, the memory map will be closed once we are 
+        :param close_on_deletion: if True, the memory map will be closed once we are
             being deleted"""
         inst = DecompressMemMapReader(m, close_on_deletion, 0)
-        type, size = inst._parse_header_info()
-        return type, size, inst
+        typ, size = inst._parse_header_info()
+        return typ, size, inst
 
     def data(self):
         """:return: random access compatible data we are working on"""
-        return self._m 
-    
+        return self._m
+
     def compressed_bytes_read(self):
         """
-        :return: number of compressed bytes read. This includes the bytes it 
+        :return: number of compressed bytes read. This includes the bytes it
             took to decompress the header ( if there was one )"""
         # ABSTRACT: When decompressing a byte stream, it can be that the first
-        # x bytes which were requested match the first x bytes in the loosely 
+        # x bytes which were requested match the first x bytes in the loosely
         # compressed datastream. This is the worst-case assumption that the reader
         # does, it assumes that it will get at least X bytes from X compressed bytes
         # in call cases.
-        # The caveat is that the object, according to our known uncompressed size, 
+        # The caveat is that the object, according to our known uncompressed size,
         # is already complete, but there are still some bytes left in the compressed
         # stream that contribute to the amount of compressed bytes.
         # How can we know that we are truly done, and have read all bytes we need
-        # to read ? 
-        # Without help, we cannot know, as we need to obtain the status of the 
+        # to read ?
+        # Without help, we cannot know, as we need to obtain the status of the
         # decompression. If it is not finished, we need to decompress more data
         # until it is finished, to yield the actual number of compressed bytes
         # belonging to the decompressed object
-        # We are using a custom zlib module for this, if its not present, 
+        # We are using a custom zlib module for this, if its not present,
         # we try to put in additional bytes up for decompression if feasible
         # and check for the unused_data.
-        
+
         # Only scrub the stream forward if we are officially done with the
         # bytes we were to have.
         if self._br == self._s and not self._zip.unused_data:
@@ -171,47 +176,47 @@ def compressed_bytes_read(self):
                     self.read(mmap.PAGESIZE)
                 # END scrub-loop default zlib
             # END handle stream scrubbing
-            
+
             # reset bytes read, just to be sure
             self._br = self._s
         # END handle stream scrubbing
-        
+
         # unused data ends up in the unconsumed tail, which was removed
         # from the count already
         return self._cbr
-        
-    #} END interface 
-        
+
+    #} END interface
+
     def seek(self, offset, whence=getattr(os, 'SEEK_SET', 0)):
         """Allows to reset the stream to restart reading
         :raise ValueError: If offset and whence are not 0"""
         if offset != 0 or whence != getattr(os, 'SEEK_SET', 0):
             raise ValueError("Can only seek to position 0")
         # END handle offset
-        
+
         self._zip = zlib.decompressobj()
         self._br = self._cws = self._cwe = self._cbr = 0
         if self._phi:
             self._phi = False
             del(self._s)        # trigger header parsing on first access
         # END skip header
-    
+
     def read(self, size=-1):
         if size < 1:
             size = self._s - self._br
         else:
             size = min(size, self._s - self._br)
         # END clamp size
-        
+
         if size == 0:
-            return str()
+            return bytes()
         # END handle depletion
-    
-    
-        # deplete the buffer, then just continue using the decompress object 
-        # which has an own buffer. We just need this to transparently parse the 
+
+
+        # deplete the buffer, then just continue using the decompress object
+        # which has an own buffer. We just need this to transparently parse the
         # header from the zlib stream
-        dat = str()
+        dat = bytes()
         if self._buf:
             if self._buflen >= size:
                 # have enough data
@@ -223,26 +228,26 @@ def read(self, size=-1):
                 dat = self._buf.read()      # ouch, duplicates data
                 size -= self._buflen
                 self._br += self._buflen
-                
+
                 self._buflen = 0
                 self._buf = None
             # END handle buffer len
         # END handle buffer
-        
+
         # decompress some data
-        # Abstract: zlib needs to operate on chunks of our memory map ( which may 
+        # Abstract: zlib needs to operate on chunks of our memory map ( which may
         # be large ), as it will otherwise and always fill in the 'unconsumed_tail'
-        # attribute which possible reads our whole map to the end, forcing 
+        # attribute which possible reads our whole map to the end, forcing
         # everything to be read from disk even though just a portion was requested.
-        # As this would be a nogo, we workaround it by passing only chunks of data, 
-        # moving the window into the memory map along as we decompress, which keeps 
+        # As this would be a nogo, we workaround it by passing only chunks of data,
+        # moving the window into the memory map along as we decompress, which keeps
         # the tail smaller than our chunk-size. This causes 'only' the chunk to be
         # copied once, and another copy of a part of it when it creates the unconsumed
         # tail. We have to use it to hand in the appropriate amount of bytes durin g
         # the next read.
         tail = self._zip.unconsumed_tail
         if tail:
-            # move the window, make it as large as size demands. For code-clarity, 
+            # move the window, make it as large as size demands. For code-clarity,
             # we just take the chunk from our map again instead of reusing the unconsumed
             # tail. The latter one would safe some memory copying, but we could end up
             # with not getting enough data uncompressed, so we had to sort that out as well.
@@ -253,18 +258,18 @@ def read(self, size=-1):
         else:
             cws = self._cws
             self._cws = self._cwe
-            self._cwe = cws + size 
+            self._cwe = cws + size
         # END handle tail
-        
-        
+
+
         # if window is too small, make it larger so zip can decompress something
         if self._cwe - self._cws < 8:
             self._cwe = self._cws + 8
         # END adjust winsize
-        
-        # takes a slice, but doesn't copy the data, it says ... 
+
+        # takes a slice, but doesn't copy the data, it says ...
         indata = buffer(self._m, self._cws, self._cwe - self._cws)
-        
+
         # get the actual window end to be sure we don't use it for computations
         self._cwe = self._cws + len(indata)
         dcompdat = self._zip.decompress(indata, size)
@@ -274,13 +279,13 @@ def read(self, size=-1):
         # if we hit the end of the stream
         self._cbr += len(indata) - len(self._zip.unconsumed_tail)
         self._br += len(dcompdat)
-        
+
         if dat:
             dcompdat = dat + dcompdat
         # END prepend our cached data
-            
-        # it can happen, depending on the compression, that we get less bytes 
-        # than ordered as it needs the final portion of the data as well. 
+
+        # it can happen, depending on the compression, that we get less bytes
+        # than ordered as it needs the final portion of the data as well.
         # Recursively resolve that.
         # Note: dcompdat can be empty even though we still appear to have bytes
         # to read, if we are called by compressed_bytes_read - it manipulates
@@ -290,30 +295,30 @@ def read(self, size=-1):
         # END handle special case
         return dcompdat
 
-    
+
 class DeltaApplyReader(LazyMixin):
-    """A reader which dynamically applies pack deltas to a base object, keeping the 
+    """A reader which dynamically applies pack deltas to a base object, keeping the
     memory demands to a minimum.
-    
-    The size of the final object is only obtainable once all deltas have been 
+
+    The size of the final object is only obtainable once all deltas have been
     applied, unless it is retrieved from a pack index.
-    
+
     The uncompressed Delta has the following layout (MSB being a most significant
     bit encoded dynamic size):
-    
+
     * MSB Source Size - the size of the base against which the delta was created
     * MSB Target Size - the size of the resulting data after the delta was applied
     * A list of one byte commands (cmd) which are followed by a specific protocol:
-    
+
      * cmd & 0x80 - copy delta_data[offset:offset+size]
-     
+
       * Followed by an encoded offset into the delta data
       * Followed by an encoded size of the chunk to copy
-      
+
      *  cmd & 0x7f - insert
-     
+
       * insert cmd bytes from the delta buffer into the output stream
-      
+
      * cmd == 0 - invalid operation ( or error in delta stream )
     """
     __slots__ = (
@@ -321,38 +326,38 @@ class DeltaApplyReader(LazyMixin):
                     "_dstreams",            # tuple of delta stream readers
                     "_mm_target",           # memory map of the delta-applied data
                     "_size",                # actual number of bytes in _mm_target
-                    "_br"                   # number of bytes read 
+                    "_br"                   # number of bytes read
                 )
-    
+
     #{ Configuration
     k_max_memory_move = 250*1000*1000
     #} END configuration
-    
+
     def __init__(self, stream_list):
-        """Initialize this instance with a list of streams, the first stream being 
+        """Initialize this instance with a list of streams, the first stream being
         the delta to apply on top of all following deltas, the last stream being the
         base object onto which to apply the deltas"""
         assert len(stream_list) > 1, "Need at least one delta and one base stream"
-        
+
         self._bstream = stream_list[-1]
         self._dstreams = tuple(stream_list[:-1])
         self._br = 0
-        
+
     def _set_cache_too_slow_without_c(self, attr):
-        # the direct algorithm is fastest and most direct if there is only one 
+        # the direct algorithm is fastest and most direct if there is only one
         # delta. Also, the extra overhead might not be worth it for items smaller
-        # than X - definitely the case in python, every function call costs 
+        # than X - definitely the case in python, every function call costs
         # huge amounts of time
         # if len(self._dstreams) * self._bstream.size < self.k_max_memory_move:
         if len(self._dstreams) == 1:
             return self._set_cache_brute_(attr)
-        
-        # Aggregate all deltas into one delta in reverse order. Hence we take 
+
+        # Aggregate all deltas into one delta in reverse order. Hence we take
         # the last delta, and reverse-merge its ancestor delta, until we receive
         # the final delta data stream.
         # print "Handling %i delta streams, sizes: %s" % (len(self._dstreams), [ds.size for ds in self._dstreams])
         dcl = connect_deltas(self._dstreams)
-        
+
         # call len directly, as the (optional) c version doesn't implement the sequence
         # protocol
         if dcl.rbound() == 0:
@@ -360,22 +365,23 @@ def _set_cache_too_slow_without_c(self, attr):
             self._mm_target = allocate_memory(0)
             return
         # END handle empty list
-        
+
         self._size = dcl.rbound()
         self._mm_target = allocate_memory(self._size)
-        
+
         bbuf = allocate_memory(self._bstream.size)
         stream_copy(self._bstream.read, bbuf.write, self._bstream.size, 256 * mmap.PAGESIZE)
-        
+
         # APPLY CHUNKS
         write = self._mm_target.write
         dcl.apply(bbuf, write)
-        
+
         self._mm_target.seek(0)
-        
+
     def _set_cache_brute_(self, attr):
         """If we are here, we apply the actual deltas"""
-        
+        from gitdb.utils.compat import buffer
+
         # TODO: There should be a special case if there is only one stream
         # Then the default-git algorithm should perform a tad faster, as the
         # delta is not peaked into, causing less overhead.
@@ -388,37 +394,37 @@ def _set_cache_brute_(self, attr):
             buffer_info_list.append((buffer(buf, offset), offset, src_size, target_size))
             max_target_size = max(max_target_size, target_size)
         # END for each delta stream
-        
+
         # sanity check - the first delta to apply should have the same source
         # size as our actual base stream
         base_size = self._bstream.size
         target_size = max_target_size
-        
+
         # if we have more than 1 delta to apply, we will swap buffers, hence we must
         # assure that all buffers we use are large enough to hold all the results
         if len(self._dstreams) > 1:
             base_size = target_size = max(base_size, max_target_size)
         # END adjust buffer sizes
-            
-        
+
+
         # Allocate private memory map big enough to hold the first base buffer
         # We need random access to it
         bbuf = allocate_memory(base_size)
         stream_copy(self._bstream.read, bbuf.write, base_size, 256 * mmap.PAGESIZE)
-        
+
         # allocate memory map large enough for the largest (intermediate) target
-        # We will use it as scratch space for all delta ops. If the final 
+        # We will use it as scratch space for all delta ops. If the final
         # target buffer is smaller than our allocated space, we just use parts
         # of it upon return.
         tbuf = allocate_memory(target_size)
-        
-        # for each delta to apply, memory map the decompressed delta and 
+
+        # for each delta to apply, memory map the decompressed delta and
         # work on the op-codes to reconstruct everything.
         # For the actual copying, we use a seek and write pattern of buffer
         # slices.
         final_target_size = None
         for (dbuf, offset, src_size, target_size), dstream in reversed(zip(buffer_info_list, self._dstreams)):
-            # allocate a buffer to hold all delta data - fill in the data for 
+            # allocate a buffer to hold all delta data - fill in the data for
             # fast access. We do this as we know that reading individual bytes
             # from our stream would be slower than necessary ( although possible )
             # The dbuf buffer contains commands after the first two MSB sizes, the
@@ -427,37 +433,37 @@ def _set_cache_brute_(self, attr):
             ddata.write(dbuf)
             # read the rest from the stream. The size we give is larger than necessary
             stream_copy(dstream.read, ddata.write, dstream.size, 256*mmap.PAGESIZE)
-            
+
             #######################################################################
             if 'c_apply_delta' in globals():
                 c_apply_delta(bbuf, ddata, tbuf);
             else:
                 apply_delta_data(bbuf, src_size, ddata, len(ddata), tbuf.write)
             #######################################################################
-            
-            # finally, swap out source and target buffers. The target is now the 
+
+            # finally, swap out source and target buffers. The target is now the
             # base for the next delta to apply
             bbuf, tbuf = tbuf, bbuf
             bbuf.seek(0)
             tbuf.seek(0)
             final_target_size = target_size
         # END for each delta to apply
-        
+
         # its already seeked to 0, constrain it to the actual size
         # NOTE: in the end of the loop, it swaps buffers, hence our target buffer
         # is not tbuf, but bbuf !
         self._mm_target = bbuf
         self._size = final_target_size
-        
-    
+
+
     #{ Configuration
     if not has_perf_mod:
         _set_cache_ = _set_cache_brute_
     else:
         _set_cache_ = _set_cache_too_slow_without_c
-    
+
     #} END configuration
-        
+
     def read(self, count=0):
         bl = self._size - self._br      # bytes left
         if count < 1 or count > bl:
@@ -467,63 +473,63 @@ def read(self, count=0):
         data = self._mm_target.read(count)
         self._br += len(data)
         return data
-        
+
     def seek(self, offset, whence=getattr(os, 'SEEK_SET', 0)):
         """Allows to reset the stream to restart reading
-        
+
         :raise ValueError: If offset and whence are not 0"""
         if offset != 0 or whence != getattr(os, 'SEEK_SET', 0):
             raise ValueError("Can only seek to position 0")
         # END handle offset
         self._br = 0
         self._mm_target.seek(0)
-        
-    #{ Interface 
-    
+
+    #{ Interface
+
     @classmethod
     def new(cls, stream_list):
         """
         Convert the given list of streams into a stream which resolves deltas
         when reading from it.
-        
+
         :param stream_list: two or more stream objects, first stream is a Delta
             to the object that you want to resolve, followed by N additional delta
             streams. The list's last stream must be a non-delta stream.
-            
-        :return: Non-Delta OPackStream object whose stream can be used to obtain 
+
+        :return: Non-Delta OPackStream object whose stream can be used to obtain
             the decompressed resolved data
         :raise ValueError: if the stream list cannot be handled"""
         if len(stream_list) < 2:
             raise ValueError("Need at least two streams")
         # END single object special handling
-        
+
         if stream_list[-1].type_id in delta_types:
             raise ValueError("Cannot resolve deltas if there is no base object stream, last one was type: %s" % stream_list[-1].type)
         # END check stream
-        
+
         return cls(stream_list)
-        
+
     #} END interface
-    
-    
+
+
     #{ OInfo like Interface
-    
+
     @property
     def type(self):
         return self._bstream.type
-        
+
     @property
     def type_id(self):
         return self._bstream.type_id
-        
+
     @property
     def size(self):
         """:return: number of uncompressed bytes in the stream"""
         return self._size
-        
-    #} END oinfo like interface 
-    
-    
+
+    #} END oinfo like interface
+
+
 #} END RO streams
 
 
@@ -533,7 +539,7 @@ class Sha1Writer(object):
     """Simple stream writer which produces a sha whenever you like as it degests
     everything it is supposed to write"""
     __slots__ = "sha1"
-    
+
     def __init__(self):
         self.sha1 = make_sha()
 
@@ -541,33 +547,36 @@ def __init__(self):
 
     def write(self, data):
         """:raise IOError: If not all bytes could be written
-        :return: lenght of incoming data"""
+        :return: length of incoming data"""
+
+        data = force_bytes(data)
         self.sha1.update(data)
+
         return len(data)
 
-    # END stream interface 
+    # END stream interface
 
     #{ Interface
-    
+
     def sha(self, as_hex = False):
         """:return: sha so far
         :param as_hex: if True, sha will be hex-encoded, binary otherwise"""
         if as_hex:
             return self.sha1.hexdigest()
         return self.sha1.digest()
-    
-    #} END interface 
+
+    #} END interface
 
 
 class FlexibleSha1Writer(Sha1Writer):
-    """Writer producing a sha1 while passing on the written bytes to the given 
+    """Writer producing a sha1 while passing on the written bytes to the given
     write function"""
     __slots__ = 'writer'
-    
+
     def __init__(self, writer):
         Sha1Writer.__init__(self)
         self.writer = writer
-    
+
     def write(self, data):
         Sha1Writer.write(self, data)
         self.writer(data)
@@ -578,20 +587,23 @@ class ZippedStoreShaWriter(Sha1Writer):
     __slots__ = ('buf', 'zip')
     def __init__(self):
         Sha1Writer.__init__(self)
-        self.buf = StringIO()
+        self.buf = BytesIO()
         self.zip = zlib.compressobj(zlib.Z_BEST_SPEED)
-    
+
     def __getattr__(self, attr):
         return getattr(self.buf, attr)
-    
+
     def write(self, data):
+        data = force_bytes(data)
+
         alen = Sha1Writer.write(self, data)
         self.buf.write(self.zip.compress(data))
+
         return alen
-        
+
     def close(self):
         self.buf.write(self.zip.flush())
-        
+
     def seek(self, offset, whence=getattr(os, 'SEEK_SET', 0)):
         """Seeking currently only supports to rewind written data
         Multiple writes are not supported"""
@@ -599,23 +611,23 @@ def seek(self, offset, whence=getattr(os, 'SEEK_SET', 0)):
             raise ValueError("Can only seek to position 0")
         # END handle offset
         self.buf.seek(0)
-        
+
     def getvalue(self):
         """:return: string value from the current stream position to the end"""
         return self.buf.getvalue()
 
 
 class FDCompressedSha1Writer(Sha1Writer):
-    """Digests data written to it, making the sha available, then compress the 
+    """Digests data written to it, making the sha available, then compress the
     data and write it to the file descriptor
-    
+
     **Note:** operates on raw file descriptors
     **Note:** for this to work, you have to use the close-method of this instance"""
     __slots__ = ("fd", "sha1", "zip")
-    
+
     # default exception
     exc = IOError("Failed to write all bytes to filedescriptor")
-    
+
     def __init__(self, fd):
         super(FDCompressedSha1Writer, self).__init__()
         self.fd = fd
@@ -626,11 +638,15 @@ def __init__(self, fd):
     def write(self, data):
         """:raise IOError: If not all bytes could be written
         :return: lenght of incoming data"""
+        data = force_bytes(data)
+
         self.sha1.update(data)
         cdata = self.zip.compress(data)
         bytes_written = write(self.fd, cdata)
+
         if bytes_written != len(cdata):
             raise self.exc
+
         return len(data)
 
     def close(self):
@@ -643,33 +659,33 @@ def close(self):
 
 
 class FDStream(object):
-    """A simple wrapper providing the most basic functions on a file descriptor 
+    """A simple wrapper providing the most basic functions on a file descriptor
     with the fileobject interface. Cannot use os.fdopen as the resulting stream
     takes ownership"""
     __slots__ = ("_fd", '_pos')
     def __init__(self, fd):
         self._fd = fd
         self._pos = 0
-        
+
     def write(self, data):
         self._pos += len(data)
         os.write(self._fd, data)
-    
+
     def read(self, count=0):
         if count == 0:
             count = os.path.getsize(self._filepath)
         # END handle read everything
-            
+
         bytes = os.read(self._fd, count)
         self._pos += len(bytes)
         return bytes
-        
+
     def fileno(self):
         return self._fd
-        
+
     def tell(self):
         return self._pos
-        
+
     def close(self):
         close(self._fd)
 
@@ -678,17 +694,15 @@ class NullStream(object):
     """A stream that does nothing but providing a stream interface.
     Use it like /dev/null"""
     __slots__ = tuple()
-        
+
     def read(self, size=0):
         return ''
-        
+
     def close(self):
         pass
-        
+
     def write(self, data):
         return len(data)
 
 
 #} END W streams
-
-
diff --git a/gitdb/test/__init__.py b/gitdb/test/__init__.py
index f805944..ca104c0 100644
--- a/gitdb/test/__init__.py
+++ b/gitdb/test/__init__.py
@@ -5,11 +5,11 @@
 
 import gitdb.util
 
-#{ Initialization 
+#{ Initialization
 def _init_pool():
     """Assure the pool is actually threaded"""
     size = 2
-    print "Setting ThreadPool to %i" % size
+    print("Setting ThreadPool to %i" % size)
     gitdb.util.pool.set_size(size)
 
 
diff --git a/gitdb/test/db/lib.py b/gitdb/test/db/lib.py
index 62614ee..38747de 100644
--- a/gitdb/test/db/lib.py
+++ b/gitdb/test/db/lib.py
@@ -9,60 +9,63 @@
     ZippedStoreShaWriter,
     fixture_path,
     TestBase
-    )
+)
 
 from gitdb.stream import Sha1Writer
 
 from gitdb.base import (
-                            IStream,
-                            OStream,
-                            OInfo
-                        )
-                
+    IStream,
+    OStream,
+    OInfo
+)
+
 from gitdb.exc import BadObject
 from gitdb.typ import str_blob_type
+from gitdb.utils.encoding import force_bytes
 
 from async import IteratorReader
-from cStringIO import StringIO
+
+from io import BytesIO
+
 from struct import pack
 
 
 __all__ = ('TestDBBase', 'with_rw_directory', 'with_packs_rw', 'fixture_path')
-        
+
 class TestDBBase(TestBase):
     """Base class providing testing routines on databases"""
-    
+
     # data
     two_lines = "1234\nhello world"
     all_data = (two_lines, )
-    
+
     def _assert_object_writing_simple(self, db):
         # write a bunch of objects and query their streams and info
         null_objs = db.size()
         ni = 250
-        for i in xrange(ni):
+        for i in range(ni):
             data = pack(">L", i)
-            istream = IStream(str_blob_type, len(data), StringIO(data))
+            istream = IStream(str_blob_type, len(data), BytesIO(data))
             new_istream = db.store(istream)
             assert new_istream is istream
             assert db.has_object(istream.binsha)
-            
+
             info = db.info(istream.binsha)
             assert isinstance(info, OInfo)
             assert info.type == istream.type and info.size == istream.size
-            
+
             stream = db.stream(istream.binsha)
             assert isinstance(stream, OStream)
             assert stream.binsha == info.binsha and stream.type == info.type
             assert stream.read() == data
         # END for each item
-        
+
         assert db.size() == null_objs + ni
         shas = list(db.sha_iter())
         assert len(shas) == db.size()
         assert len(shas[0]) == 20
-        
-    
+
+
     def _assert_object_writing(self, db):
         """General tests to verify object writing, compatible to ObjectDBW
         **Note:** requires write access to the database"""
@@ -76,81 +79,80 @@ def _assert_object_writing(self, db):
                     ostream = ostreamcls()
                     assert isinstance(ostream, Sha1Writer)
                 # END create ostream
-                
+
                 prev_ostream = db.set_ostream(ostream)
-                assert type(prev_ostream) in ostreams or prev_ostream in ostreams 
-                    
-                istream = IStream(str_blob_type, len(data), StringIO(data))
-                
+                assert type(prev_ostream) in ostreams or prev_ostream in ostreams
+                istream = IStream(str_blob_type, len(data), BytesIO(data.encode("ascii")))
+
                 # store returns same istream instance, with new sha set
                 my_istream = db.store(istream)
                 sha = istream.binsha
                 assert my_istream is istream
                 assert db.has_object(sha) != dry_run
-                assert len(sha) == 20   
-                
+                assert len(sha) == 20
+
                 # verify data - the slow way, we want to run code
                 if not dry_run:
                     info = db.info(sha)
                     assert str_blob_type == info.type
                     assert info.size == len(data)
-                    
+
                     ostream = db.stream(sha)
-                    assert ostream.read() == data
+                    assert ostream.read() == force_bytes(data)
                     assert ostream.type == str_blob_type
                     assert ostream.size == len(data)
                 else:
                     self.failUnlessRaises(BadObject, db.info, sha)
                     self.failUnlessRaises(BadObject, db.stream, sha)
-                    
+
                     # DIRECT STREAM COPY
                     # our data hase been written in object format to the StringIO
                     # we pasesd as output stream. No physical database representation
                     # was created.
-                    # Test direct stream copy of object streams, the result must be 
+                    # Test direct stream copy of object streams, the result must be
                     # identical to what we fed in
                     ostream.seek(0)
                     istream.stream = ostream
                     assert istream.binsha is not None
                     prev_sha = istream.binsha
-                    
+
                     db.set_ostream(ZippedStoreShaWriter())
                     db.store(istream)
                     assert istream.binsha == prev_sha
                     new_ostream = db.ostream()
-                    
+
                     # note: only works as long our store write uses the same compression
                     # level, which is zip_best
                     assert ostream.getvalue() == new_ostream.getvalue()
             # END for each data set
         # END for each dry_run mode
-        
+
     def _assert_object_writing_async(self, db):
         """Test generic object writing using asynchronous access"""
         ni = 5000
         def istream_generator(offset=0, ni=ni):
-            for data_src in xrange(ni):
-                data = str(data_src + offset)
-                yield IStream(str_blob_type, len(data), StringIO(data))
+            for data_src in range(ni):
+                data = bytes(data_src + offset)
+                yield IStream(str_blob_type, len(data), BytesIO(data))
             # END for each item
         # END generator utility
-        
+
         # for now, we are very trusty here as we expect it to work if it worked
         # in the single-stream case
-        
+
         # write objects
         reader = IteratorReader(istream_generator())
         istream_reader = db.store_async(reader)
         istreams = istream_reader.read()        # read all
         assert istream_reader.task().error() is None
         assert len(istreams) == ni
-        
+
         for stream in istreams:
             assert stream.error is None
             assert len(stream.binsha) == 20
             assert isinstance(stream, IStream)
         # END assert each stream
-        
+
         # test has-object-async - we must have all previously added ones
         reader = IteratorReader( istream.binsha for istream in istreams )
         hasobject_reader = db.has_object_async(reader)
@@ -160,11 +162,11 @@ def istream_generator(offset=0, ni=ni):
             count += 1
         # END for each sha
         assert count == ni
-        
+
         # read the objects we have just written
         reader = IteratorReader( istream.binsha for istream in istreams )
         ostream_reader = db.stream_async(reader)
-        
+
         # read items individually to prevent hitting possible sys-limits
         count = 0
         for ostream in ostream_reader:
@@ -173,30 +175,30 @@ def istream_generator(offset=0, ni=ni):
         # END for each ostream
         assert ostream_reader.task().error() is None
         assert count == ni
-        
+
         # get info about our items
         reader = IteratorReader( istream.binsha for istream in istreams )
         info_reader = db.info_async(reader)
-        
+
         count = 0
         for oinfo in info_reader:
             assert isinstance(oinfo, OInfo)
             count += 1
         # END for each oinfo instance
         assert count == ni
-        
-          
+
+
         # combined read-write using a converter
         # add 2500 items, and obtain their output streams
         nni = 2500
         reader = IteratorReader(istream_generator(offset=ni, ni=nni))
         istream_to_sha = lambda istreams: [ istream.binsha for istream in istreams ]
-        
+
         istream_reader = db.store_async(reader)
         istream_reader.set_post_cb(istream_to_sha)
-        
+
         ostream_reader = db.stream_async(istream_reader)
-        
+
         count = 0
         # read it individually, otherwise we might run into the ulimit
         for ostream in ostream_reader:
@@ -204,5 +206,3 @@ def istream_generator(offset=0, ni=ni):
             count += 1
         # END for each ostream
         assert count == nni
-        
-        
diff --git a/gitdb/test/db/test_git.py b/gitdb/test/db/test_git.py
index 1ef577a..cce2b9c 100644
--- a/gitdb/test/db/test_git.py
+++ b/gitdb/test/db/test_git.py
@@ -2,20 +2,20 @@
 #
 # This module is part of GitDB and is released under
 # the New BSD License: http://www.opensource.org/licenses/bsd-license.php
-from lib import *
+from gitdb.test.db.lib import *
 from gitdb.exc import BadObject
 from gitdb.db import GitDB
 from gitdb.base import OStream, OInfo
 from gitdb.util import hex_to_bin, bin_to_hex
-        
+
 class TestGitDB(TestDBBase):
-    
+
     def test_reading(self):
         gdb = GitDB(fixture_path('../../../.git/objects'))
-        
+
         # we have packs and loose objects, alternates doesn't necessarily exist
         assert 1 < len(gdb.databases()) < 4
-        
+
         # access should be possible
         gitdb_sha = hex_to_bin("5690fd0d3304f378754b23b098bd7cb5f4aa1976")
         assert isinstance(gdb.info(gitdb_sha), OInfo)
@@ -23,25 +23,25 @@ def test_reading(self):
         assert gdb.size() > 200
         sha_list = list(gdb.sha_iter())
         assert len(sha_list) == gdb.size()
-        
-        
-        # This is actually a test for compound functionality, but it doesn't 
+
+
+        # This is actually a test for compound functionality, but it doesn't
         # have a separate test module
         # test partial shas
         # this one as uneven and quite short
         assert gdb.partial_to_complete_sha_hex('155b6') == hex_to_bin("155b62a9af0aa7677078331e111d0f7aa6eb4afc")
-        
+
         # mix even/uneven hexshas
         for i, binsha in enumerate(sha_list):
             assert gdb.partial_to_complete_sha_hex(bin_to_hex(binsha)[:8-(i%2)]) == binsha
         # END for each sha
-        
+
         self.failUnlessRaises(BadObject, gdb.partial_to_complete_sha_hex, "0000")
-        
+
     @with_rw_directory
     def test_writing(self, path):
         gdb = GitDB(path)
-        
+
         # its possible to write objects
         self._assert_object_writing(gdb)
         self._assert_object_writing_async(gdb)
diff --git a/gitdb/test/db/test_loose.py b/gitdb/test/db/test_loose.py
index d7e1d01..5e42b63 100644
--- a/gitdb/test/db/test_loose.py
+++ b/gitdb/test/db/test_loose.py
@@ -2,33 +2,32 @@
 #
 # This module is part of GitDB and is released under
 # the New BSD License: http://www.opensource.org/licenses/bsd-license.php
-from lib import *
+from gitdb.test.db.lib import *
 from gitdb.db import LooseObjectDB
 from gitdb.exc import BadObject
 from gitdb.util import bin_to_hex
-        
+
 class TestLooseDB(TestDBBase):
-    
+
     @with_rw_directory
     def test_basics(self, path):
         ldb = LooseObjectDB(path)
-        
+
         # write data
         self._assert_object_writing(ldb)
         self._assert_object_writing_async(ldb)
-    
+
         # verify sha iteration and size
         shas = list(ldb.sha_iter())
         assert shas and len(shas[0]) == 20
-        
+
         assert len(shas) == ldb.size()
-        
+
         # verify find short object
         long_sha = bin_to_hex(shas[-1])
         for short_sha in (long_sha[:20], long_sha[:5]):
             assert bin_to_hex(ldb.partial_to_complete_sha_hex(short_sha)) == long_sha
         # END for each sha
-        
+
         self.failUnlessRaises(BadObject, ldb.partial_to_complete_sha_hex, '0000')
         # raises if no object could be foudn
-        
diff --git a/gitdb/test/db/test_mem.py b/gitdb/test/db/test_mem.py
index df428e2..9235b21 100644
--- a/gitdb/test/db/test_mem.py
+++ b/gitdb/test/db/test_mem.py
@@ -2,29 +2,29 @@
 #
 # This module is part of GitDB and is released under
 # the New BSD License: http://www.opensource.org/licenses/bsd-license.php
-from lib import *
+from gitdb.test.db.lib import *
 from gitdb.db import (
-                        MemoryDB,
-                        LooseObjectDB
-                    )
-        
+    MemoryDB,
+    LooseObjectDB
+)
+
 class TestMemoryDB(TestDBBase):
-    
+
     @with_rw_directory
     def test_writing(self, path):
         mdb = MemoryDB()
-        
+
         # write data
         self._assert_object_writing_simple(mdb)
-        
+
         # test stream copy
         ldb = LooseObjectDB(path)
         assert ldb.size() == 0
         num_streams_copied = mdb.stream_copy(mdb.sha_iter(), ldb)
         assert num_streams_copied == mdb.size()
-        
+
         assert ldb.size() == mdb.size()
         for sha in mdb.sha_iter():
             assert ldb.has_object(sha)
-            assert ldb.stream(sha).read() == mdb.stream(sha).read() 
+            assert ldb.stream(sha).read() == mdb.stream(sha).read()
         # END verify objects where copied and are equal
diff --git a/gitdb/test/db/test_pack.py b/gitdb/test/db/test_pack.py
index f4cb5bb..f5a4dcb 100644
--- a/gitdb/test/db/test_pack.py
+++ b/gitdb/test/db/test_pack.py
@@ -2,7 +2,7 @@
 #
 # This module is part of GitDB and is released under
 # the New BSD License: http://www.opensource.org/licenses/bsd-license.php
-from lib import *
+from gitdb.test.db.lib import *
 from gitdb.db import PackedDB
 from gitdb.test.lib import fixture_path
 
@@ -12,45 +12,45 @@
 import random
 
 class TestPackDB(TestDBBase):
-    
+
     @with_rw_directory
     @with_packs_rw
     def test_writing(self, path):
         pdb = PackedDB(path)
-        
+
         # on demand, we init our pack cache
         num_packs = len(pdb.entities())
         assert pdb._st_mtime != 0
-        
-        # test pack directory changed: 
+
+        # test pack directory changed:
         # packs removed - rename a file, should affect the glob
         pack_path = pdb.entities()[0].pack().path()
         new_pack_path = pack_path + "renamed"
         os.rename(pack_path, new_pack_path)
-        
+
         pdb.update_cache(force=True)
         assert len(pdb.entities()) == num_packs - 1
-        
+
         # packs added
         os.rename(new_pack_path, pack_path)
         pdb.update_cache(force=True)
         assert len(pdb.entities()) == num_packs
-    
+
         # bang on the cache
         # access the Entities directly, as there is no iteration interface
         # yet ( or required for now )
         sha_list = list(pdb.sha_iter())
         assert len(sha_list) == pdb.size()
-        
+
         # hit all packs in random order
         random.shuffle(sha_list)
-        
+
         for sha in sha_list:
             info = pdb.info(sha)
             stream = pdb.stream(sha)
         # END for each sha to query
-        
-        
+
+
         # test short finding - be a bit more brutal here
         max_bytes = 19
         min_bytes = 2
@@ -64,10 +64,10 @@ def test_writing(self, path):
                 pass # valid, we can have short objects
             # END exception handling
         # END for each sha to find
-        
+
         # we should have at least one ambiguous, considering the small sizes
-        # but in our pack, there is no ambigious ... 
+        # but in our pack, there is no ambigious ...
         # assert num_ambiguous
-        
+
         # non-existing
         self.failUnlessRaises(BadObject, pdb.partial_to_complete_sha, "\0\0", 4)
diff --git a/gitdb/test/db/test_ref.py b/gitdb/test/db/test_ref.py
index 1637bff..a1387ee 100644
--- a/gitdb/test/db/test_ref.py
+++ b/gitdb/test/db/test_ref.py
@@ -2,59 +2,56 @@
 #
 # This module is part of GitDB and is released under
 # the New BSD License: http://www.opensource.org/licenses/bsd-license.php
-from lib import *
+from gitdb.test.db.lib import *
 from gitdb.db import ReferenceDB
 
 from gitdb.util import (
-                        NULL_BIN_SHA,
-                        hex_to_bin
-                        )
+    NULL_BIN_SHA,
+    hex_to_bin
+)
 
 import os
-        
+
 class TestReferenceDB(TestDBBase):
-    
+
     def make_alt_file(self, alt_path, alt_list):
         """Create an alternates file which contains the given alternates.
         The list can be empty"""
         alt_file = open(alt_path, "wb")
         for alt in alt_list:
-            alt_file.write(alt + "\n")
+            alt_file.write(alt.encode("utf-8") + "\n".encode("ascii"))
         alt_file.close()
-    
+
     @with_rw_directory
     def test_writing(self, path):
-        NULL_BIN_SHA = '\0'  * 20
-        
+        NULL_BIN_SHA = '\0'.encode("ascii") * 20
+
         alt_path = os.path.join(path, 'alternates')
         rdb = ReferenceDB(alt_path)
         assert len(rdb.databases()) == 0
         assert rdb.size() == 0
         assert len(list(rdb.sha_iter())) == 0
-        
+
         # try empty, non-existing
         assert not rdb.has_object(NULL_BIN_SHA)
-        
-        
+
         # setup alternate file
         # add two, one is invalid
         own_repo_path = fixture_path('../../../.git/objects')       # use own repo
         self.make_alt_file(alt_path, [own_repo_path, "invalid/path"])
         rdb.update_cache()
         assert len(rdb.databases()) == 1
-        
+
         # we should now find a default revision of ours
         gitdb_sha = hex_to_bin("5690fd0d3304f378754b23b098bd7cb5f4aa1976")
         assert rdb.has_object(gitdb_sha)
-        
+
         # remove valid
         self.make_alt_file(alt_path, ["just/one/invalid/path"])
         rdb.update_cache()
         assert len(rdb.databases()) == 0
-        
+
         # add valid
         self.make_alt_file(alt_path, [own_repo_path])
         rdb.update_cache()
         assert len(rdb.databases()) == 1
-        
-        
diff --git a/gitdb/test/lib.py b/gitdb/test/lib.py
index ac8473a..75342f1 100644
--- a/gitdb/test/lib.py
+++ b/gitdb/test/lib.py
@@ -4,19 +4,20 @@
 # the New BSD License: http://www.opensource.org/licenses/bsd-license.php
 """Utilities used in ODB testing"""
 from gitdb import (
-    OStream, 
+    OStream,
     )
-from gitdb.stream import ( 
-                            Sha1Writer, 
-                            ZippedStoreShaWriter
-                        )
+from gitdb.stream import (
+    Sha1Writer,
+    ZippedStoreShaWriter
+)
 
 from gitdb.util import zlib
 
 import sys
 import random
 from array import array
-from cStringIO import StringIO
+
+from io import StringIO
 
 import glob
 import unittest
@@ -30,14 +31,14 @@
 
 class TestBase(unittest.TestCase):
     """Base class for all tests"""
-    
+
 
 #} END bases
 
 #{ Decorators
 
 def with_rw_directory(func):
-    """Create a temporary directory which can be written to, remove it if the 
+    """Create a temporary directory which can be written to, remove it if the
     test suceeds, but leave it otherwise to aid additional debugging"""
     def wrapper(self):
         path = tempfile.mktemp(prefix=func.__name__)
@@ -47,12 +48,12 @@ def wrapper(self):
             try:
                 return func(self, path)
             except Exception:
-                print >> sys.stderr, "Test %s.%s failed, output is at %r" % (type(self).__name__, func.__name__, path)
+                sys.stderr.write("Test %s.%s failed, output is at %r\n" % (type(self).__name__, func.__name__, path))
                 keep = True
                 raise
         finally:
             # Need to collect here to be sure all handles have been closed. It appears
-            # a windows-only issue. In fact things should be deleted, as well as 
+            # a windows-only issue. In fact things should be deleted, as well as
             # memory maps closed, once objects go out of scope. For some reason
             # though this is not the case here unless we collect explicitly.
             if not keep:
@@ -60,20 +61,20 @@ def wrapper(self):
                 shutil.rmtree(path)
         # END handle exception
     # END wrapper
-    
+
     wrapper.__name__ = func.__name__
     return wrapper
 
 
 def with_packs_rw(func):
-    """Function that provides a path into which the packs for testing should be 
+    """Function that provides a path into which the packs for testing should be
     copied. Will pass on the path to the actual function afterwards"""
     def wrapper(self, path):
         src_pack_glob = fixture_path('packs/*')
         copy_files_globbed(src_pack_glob, path, hard_link_ok=True)
         return func(self, path)
     # END wrapper
-    
+
     wrapper.__name__ = func.__name__
     return wrapper
 
@@ -86,10 +87,10 @@ def fixture_path(relapath=''):
     :param relapath: relative path into the fixtures directory, or ''
         to obtain the fixture directory itself"""
     return os.path.join(os.path.dirname(__file__), 'fixtures', relapath)
-    
+
 def copy_files_globbed(source_glob, target_dir, hard_link_ok=False):
     """Copy all files found according to the given source glob into the target directory
-    :param hard_link_ok: if True, hard links will be created if possible. Otherwise 
+    :param hard_link_ok: if True, hard links will be created if possible. Otherwise
         the files will be copied"""
     for src_file in glob.glob(source_glob):
         if hard_link_ok and hasattr(os, 'link'):
@@ -103,13 +104,13 @@ def copy_files_globbed(source_glob, target_dir, hard_link_ok=False):
             shutil.copy(src_file, target_dir)
         # END try hard link
     # END for each file to copy
-    
+
 
 def make_bytes(size_in_bytes, randomize=False):
     """:return: string with given size in bytes
     :param randomize: try to produce a very random stream"""
-    actual_size = size_in_bytes / 4
-    producer = xrange(actual_size)
+    actual_size = size_in_bytes // 4
+    producer = range(actual_size)
     if randomize:
         producer = list(producer)
         random.shuffle(producer)
@@ -120,8 +121,8 @@ def make_bytes(size_in_bytes, randomize=False):
 def make_object(type, data):
     """:return: bytes resembling an uncompressed object"""
     odata = "blob %i\0" % len(data)
-    return odata + data
-    
+    return odata.encode("ascii") + data
+
 def make_memory_file(size_in_bytes, randomize=False):
     """:return: tuple(size_of_stream, stream)
     :param randomize: try to produce a very random stream"""
@@ -137,14 +138,14 @@ def __init__(self):
             self.was_read = False
             self.bytes = 0
             self.closed = False
-            
+
         def read(self, size):
             self.was_read = True
             self.bytes = size
-            
+
         def close(self):
             self.closed = True
-            
+
         def _assert(self):
             assert self.was_read
 
@@ -153,10 +154,9 @@ class DeriveTest(OStream):
     def __init__(self, sha, type, size, stream, *args, **kwargs):
         self.myarg = kwargs.pop('myarg')
         self.args = args
-        
+
     def _assert(self):
         assert self.args
         assert self.myarg
 
 #} END stream utilitiess
-
diff --git a/gitdb/test/test_base.py b/gitdb/test/test_base.py
index d4ce428..4cca7da 100644
--- a/gitdb/test/test_base.py
+++ b/gitdb/test/test_base.py
@@ -3,10 +3,10 @@
 # This module is part of GitDB and is released under
 # the New BSD License: http://www.opensource.org/licenses/bsd-license.php
 """Test for object db"""
-from lib import (
+from gitdb.test.lib import (
         TestBase,
         DummyStream,
-        DeriveTest, 
+        DeriveTest,
     )
 
 from gitdb import *
@@ -20,33 +20,33 @@
 
 
 class TestBaseTypes(TestBase):
-    
+
     def test_streams(self):
         # test info
         sha = NULL_BIN_SHA
         s = 20
         blob_id = 3
-        
+
         info = OInfo(sha, str_blob_type, s)
         assert info.binsha == sha
         assert info.type == str_blob_type
         assert info.type_id == blob_id
         assert info.size == s
-        
+
         # test pack info
         # provides type_id
         pinfo = OPackInfo(0, blob_id, s)
         assert pinfo.type == str_blob_type
         assert pinfo.type_id == blob_id
         assert pinfo.pack_offset == 0
-        
+
         dpinfo = ODeltaPackInfo(0, blob_id, s, sha)
         assert dpinfo.type == str_blob_type
         assert dpinfo.type_id == blob_id
         assert dpinfo.delta_info == sha
         assert dpinfo.pack_offset == 0
-        
-        
+
+
         # test ostream
         stream = DummyStream()
         ostream = OStream(*(info + (stream, )))
@@ -56,33 +56,33 @@ def test_streams(self):
         assert stream.bytes == 15
         ostream.read(20)
         assert stream.bytes == 20
-        
+
         # test packstream
         postream = OPackStream(*(pinfo + (stream, )))
         assert postream.stream is stream
         postream.read(10)
         stream._assert()
         assert stream.bytes == 10
-        
+
         # test deltapackstream
         dpostream = ODeltaPackStream(*(dpinfo + (stream, )))
         dpostream.stream is stream
         dpostream.read(5)
         stream._assert()
         assert stream.bytes == 5
-        
+
         # derive with own args
         DeriveTest(sha, str_blob_type, s, stream, 'mine',myarg = 3)._assert()
-        
+
         # test istream
         istream = IStream(str_blob_type, s, stream)
         assert istream.binsha == None
         istream.binsha = sha
         assert istream.binsha == sha
-        
+
         assert len(istream.binsha) == 20
         assert len(istream.hexsha) == 40
-        
+
         assert istream.size == s
         istream.size = s * 2
         istream.size == s * 2
@@ -92,7 +92,7 @@ def test_streams(self):
         assert istream.stream is stream
         istream.stream = None
         assert istream.stream is None
-        
+
         assert istream.error is None
         istream.error = Exception()
         assert isinstance(istream.error, Exception)
diff --git a/gitdb/test/test_example.py b/gitdb/test/test_example.py
index 611ae42..c644b88 100644
--- a/gitdb/test/test_example.py
+++ b/gitdb/test/test_example.py
@@ -3,25 +3,25 @@
 # This module is part of GitDB and is released under
 # the New BSD License: http://www.opensource.org/licenses/bsd-license.php
 """Module with examples from the tutorial section of the docs"""
-from lib import *
+from gitdb.test.lib import *
 from gitdb import IStream
 from gitdb.db import LooseObjectDB
 from gitdb.util import pool
-        
-from cStringIO import StringIO
+
+from io import BytesIO
 
 from async import IteratorReader
-        
+
 class TestExamples(TestBase):
-    
+
     def test_base(self):
         ldb = LooseObjectDB(fixture_path("../../../.git/objects"))
-        
+
         for sha1 in ldb.sha_iter():
             oinfo = ldb.info(sha1)
             ostream = ldb.stream(sha1)
             assert oinfo[:3] == ostream[:3]
-            
+
             assert len(ostream.read()) == ostream.size
             assert ldb.has_object(oinfo.binsha)
         # END for each sha in database
@@ -32,33 +32,33 @@ def test_base(self):
         except UnboundLocalError:
             pass
         # END ignore exception if there are no loose objects
-            
-        data = "my data"
-        istream = IStream("blob", len(data), StringIO(data))
-        
+
+        data = "my data".encode("ascii")
+        istream = IStream("blob", len(data), BytesIO(data))
+
         # the object does not yet have a sha
         assert istream.binsha is None
         ldb.store(istream)
         # now the sha is set
         assert len(istream.binsha) == 20
         assert ldb.has_object(istream.binsha)
-        
-        
+
+
         # async operation
         # Create a reader from an iterator
         reader = IteratorReader(ldb.sha_iter())
-        
+
         # get reader for object streams
         info_reader = ldb.stream_async(reader)
-        
+
         # read one
         info = info_reader.read(1)[0]
-        
+
         # read all the rest until depletion
         ostreams = info_reader.read()
-        
+
         # set the pool to use two threads
         pool.set_size(2)
-        
+
         # synchronize the mode of operation
         pool.set_size(0)
diff --git a/gitdb/test/test_pack.py b/gitdb/test/test_pack.py
index 779155a..bcda3cf 100644
--- a/gitdb/test/test_pack.py
+++ b/gitdb/test/test_pack.py
@@ -3,29 +3,36 @@
 # This module is part of GitDB and is released under
 # the New BSD License: http://www.opensource.org/licenses/bsd-license.php
 """Test everything about packs reading and writing"""
-from lib import (
-                    TestBase,
-                    with_rw_directory, 
-                    with_packs_rw,
-                    fixture_path
-                )
+from gitdb.test.lib import (
+    TestBase,
+    with_rw_directory,
+    with_packs_rw,
+    fixture_path
+)
+
 from gitdb.stream import DeltaApplyReader
 
 from gitdb.pack import (
-                            PackEntity,
-                            PackIndexFile,
-                            PackFile
-                        )
+    PackEntity,
+    PackIndexFile,
+    PackFile
+)
 
 from gitdb.base import (
-                            OInfo, 
-                            OStream,
-                        )
+    OInfo,
+    OStream,
+)
 
 from gitdb.fun import delta_types
 from gitdb.exc import UnsupportedOperation
 from gitdb.util import to_bin_sha
-from itertools import izip, chain
+from itertools import chain
+
+try:
+    from itertools import izip
+except ImportError:
+    izip = zip
+
 from nose import SkipTest
 
 import os
@@ -39,15 +46,15 @@ def bin_sha_from_filename(filename):
 #} END utilities
 
 class TestPack(TestBase):
-    
+
     packindexfile_v1 = (fixture_path('packs/pack-c0438c19fb16422b6bbcce24387b3264416d485b.idx'), 1, 67)
     packindexfile_v2 = (fixture_path('packs/pack-11fdfa9e156ab73caae3b6da867192221f2089c2.idx'), 2, 30)
     packindexfile_v2_3_ascii = (fixture_path('packs/pack-a2bf8e71d8c18879e499335762dd95119d93d9f1.idx'), 2, 42)
     packfile_v2_1 = (fixture_path('packs/pack-c0438c19fb16422b6bbcce24387b3264416d485b.pack'), 2, packindexfile_v1[2])
     packfile_v2_2 = (fixture_path('packs/pack-11fdfa9e156ab73caae3b6da867192221f2089c2.pack'), 2, packindexfile_v2[2])
     packfile_v2_3_ascii = (fixture_path('packs/pack-a2bf8e71d8c18879e499335762dd95119d93d9f1.pack'), 2, packindexfile_v2_3_ascii[2])
-    
-    
+
+
     def _assert_index_file(self, index, version, size):
         assert index.packfile_checksum() != index.indexfile_checksum()
         assert len(index.packfile_checksum()) == 20
@@ -55,93 +62,93 @@ def _assert_index_file(self, index, version, size):
         assert index.version() == version
         assert index.size() == size
         assert len(index.offsets()) == size
-        
+
         # get all data of all objects
-        for oidx in xrange(index.size()):
+        for oidx in range(index.size()):
             sha = index.sha(oidx)
             assert oidx == index.sha_to_index(sha)
-            
+
             entry = index.entry(oidx)
             assert len(entry) == 3
-            
+
             assert entry[0] == index.offset(oidx)
             assert entry[1] == sha
             assert entry[2] == index.crc(oidx)
-            
+
             # verify partial sha
             for l in (4,8,11,17,20):
                 assert index.partial_sha_to_index(sha[:l], l*2) == oidx
-            
+
         # END for each object index in indexfile
         self.failUnlessRaises(ValueError, index.partial_sha_to_index, "\0", 2)
-        
-        
+
+
     def _assert_pack_file(self, pack, version, size):
         assert pack.version() == 2
         assert pack.size() == size
         assert len(pack.checksum()) == 20
-        
+
         num_obj = 0
         for obj in pack.stream_iter():
             num_obj += 1
             info = pack.info(obj.pack_offset)
             stream = pack.stream(obj.pack_offset)
-            
+
             assert info.pack_offset == stream.pack_offset
             assert info.type_id == stream.type_id
             assert hasattr(stream, 'read')
-            
+
             # it should be possible to read from both streams
             assert obj.read() == stream.read()
-            
+
             streams = pack.collect_streams(obj.pack_offset)
             assert streams
-            
+
             # read the stream
             try:
                 dstream = DeltaApplyReader.new(streams)
             except ValueError:
-                # ignore these, old git versions use only ref deltas, 
+                # ignore these, old git versions use only ref deltas,
                 # which we havent resolved ( as we are without an index )
                 # Also ignore non-delta streams
                 continue
             # END get deltastream
-            
+
             # read all
             data = dstream.read()
             assert len(data) == dstream.size
-            
+
             # test seek
             dstream.seek(0)
             assert dstream.read() == data
-            
-            
+
+
             # read chunks
             # NOTE: the current implementation is safe, it basically transfers
             # all calls to the underlying memory map
-            
+
         # END for each object
         assert num_obj == size
-        
-    
+
+
     def test_pack_index(self):
         # check version 1 and 2
-        for indexfile, version, size in (self.packindexfile_v1, self.packindexfile_v2): 
+        for indexfile, version, size in (self.packindexfile_v1, self.packindexfile_v2):
             index = PackIndexFile(indexfile)
             self._assert_index_file(index, version, size)
         # END run tests
-        
+
     def test_pack(self):
-        # there is this special version 3, but apparently its like 2 ... 
+        # there is this special version 3, but apparently its like 2 ...
         for packfile, version, size in (self.packfile_v2_3_ascii, self.packfile_v2_1, self.packfile_v2_2):
             pack = PackFile(packfile)
             self._assert_pack_file(pack, version, size)
         # END for each pack to test
-        
+
     @with_rw_directory
     def test_pack_entity(self, rw_dir):
         pack_objs = list()
-        for packinfo, indexinfo in (    (self.packfile_v2_1, self.packindexfile_v1), 
+        for packinfo, indexinfo in (    (self.packfile_v2_1, self.packindexfile_v1),
                                         (self.packfile_v2_2, self.packindexfile_v2),
                                         (self.packfile_v2_3_ascii, self.packindexfile_v2_3_ascii)):
             packfile, version, size = packinfo
@@ -150,7 +157,7 @@ def test_pack_entity(self, rw_dir):
             assert entity.pack().path() == packfile
             assert entity.index().path() == indexfile
             pack_objs.extend(entity.stream_iter())
-            
+
             count = 0
             for info, stream in izip(entity.info_iter(), entity.stream_iter()):
                 count += 1
@@ -158,10 +165,10 @@ def test_pack_entity(self, rw_dir):
                 assert len(info.binsha) == 20
                 assert info.type_id == stream.type_id
                 assert info.size == stream.size
-                
+
                 # we return fully resolved items, which is implied by the sha centric access
                 assert not info.type_id in delta_types
-                
+
                 # try all calls
                 assert len(entity.collect_streams(info.binsha))
                 oinfo = entity.info(info.binsha)
@@ -170,7 +177,7 @@ def test_pack_entity(self, rw_dir):
                 ostream = entity.stream(info.binsha)
                 assert isinstance(ostream, OStream)
                 assert ostream.binsha is not None
-                
+
                 # verify the stream
                 try:
                     assert entity.is_valid_stream(info.binsha, use_crc=True)
@@ -180,16 +187,16 @@ def test_pack_entity(self, rw_dir):
                 assert entity.is_valid_stream(info.binsha, use_crc=False)
             # END for each info, stream tuple
             assert count == size
-            
+
         # END for each entity
-        
+
         # pack writing - write all packs into one
         # index path can be None
         pack_path = tempfile.mktemp('', "pack", rw_dir)
         index_path = tempfile.mktemp('', 'index', rw_dir)
         iteration = 0
         def rewind_streams():
-            for obj in pack_objs: 
+            for obj in pack_objs:
                 obj.stream.seek(0)
         #END utility
         for ppath, ipath, num_obj in zip((pack_path, )*2, (index_path, None), (len(pack_objs), None)):
@@ -199,23 +206,23 @@ def rewind_streams():
                 ifile = open(ipath, 'wb')
                 iwrite = ifile.write
             #END handle ip
-            
+
             # make sure we rewind the streams ... we work on the same objects over and over again
-            if iteration > 0: 
+            if iteration > 0:
                 rewind_streams()
             #END rewind streams
             iteration += 1
-            
+
             pack_sha, index_sha = PackEntity.write_pack(pack_objs, pfile.write, iwrite, object_count=num_obj)
             pfile.close()
             assert os.path.getsize(ppath) > 100
-            
+
             # verify pack
             pf = PackFile(ppath)
             assert pf.size() == len(pack_objs)
             assert pf.version() == PackFile.pack_version_default
             assert pf.checksum() == pack_sha
-            
+
             # verify index
             if ipath is not None:
                 ifile.close()
@@ -227,7 +234,7 @@ def rewind_streams():
                 assert idx.size() == len(pack_objs)
             #END verify files exist
         #END for each packpath, indexpath pair
-        
+
         # verify the packs throughly
         rewind_streams()
         entity = PackEntity.create(pack_objs, rw_dir)
@@ -239,9 +246,9 @@ def rewind_streams():
             # END for each crc mode
         #END for each info
         assert count == len(pack_objs)
-         
-        
+
+
     def test_pack_64(self):
         # TODO: hex-edit a pack helping us to verify that we can handle 64 byte offsets
-        # of course without really needing such a huge pack 
+        # of course without really needing such a huge pack
         raise SkipTest()
diff --git a/gitdb/test/test_stream.py b/gitdb/test/test_stream.py
index 6dc2746..92755d9 100644
--- a/gitdb/test/test_stream.py
+++ b/gitdb/test/test_stream.py
@@ -3,49 +3,48 @@
 # This module is part of GitDB and is released under
 # the New BSD License: http://www.opensource.org/licenses/bsd-license.php
 """Test for object db"""
-from lib import (
-        TestBase,
-        DummyStream,
-        Sha1Writer, 
-        make_bytes, 
-        make_object,
-        fixture_path
-    )
+
+from gitdb.test.lib import (
+    TestBase,
+    DummyStream,
+    Sha1Writer,
+    make_bytes,
+    make_object,
+    fixture_path
+)
 
 from gitdb import *
 from gitdb.util import (
     NULL_HEX_SHA,
     hex_to_bin
-    )
+)
 
 from gitdb.util import zlib
 from gitdb.typ import (
     str_blob_type
-    )
+)
 
 import time
 import tempfile
 import os
 
 
-
-
 class TestStream(TestBase):
     """Test stream classes"""
-    
+
     data_sizes = (15, 10000, 1000*1024+512)
-        
+
     def _assert_stream_reader(self, stream, cdata, rewind_stream=lambda s: None):
-        """Make stream tests - the orig_stream is seekable, allowing it to be 
+        """Make stream tests - the orig_stream is seekable, allowing it to be
         rewound and reused
         :param cdata: the data we expect to read from stream, the contents
         :param rewind_stream: function called to rewind the stream to make it ready
             for reuse"""
         ns = 10
         assert len(cdata) > ns-1, "Data must be larger than %i, was %i" % (ns, len(cdata))
-        
+
         # read in small steps
-        ss = len(cdata) / ns
+        ss = len(cdata) // ns
         for i in range(ns):
             data = stream.read(ss)
             chunk = cdata[i*ss:(i+1)*ss]
@@ -55,38 +54,38 @@ def _assert_stream_reader(self, stream, cdata, rewind_stream=lambda s: None):
         if rest:
             assert rest == cdata[-len(rest):]
         # END handle rest
-        
+
         if isinstance(stream, DecompressMemMapReader):
             assert len(stream.data()) == stream.compressed_bytes_read()
         # END handle special type
-        
+
         rewind_stream(stream)
-        
+
         # read everything
         rdata = stream.read()
         assert rdata == cdata
-        
+
         if isinstance(stream, DecompressMemMapReader):
             assert len(stream.data()) == stream.compressed_bytes_read()
         # END handle special type
-        
+
     def test_decompress_reader(self):
         for close_on_deletion in range(2):
             for with_size in range(2):
                 for ds in self.data_sizes:
                     cdata = make_bytes(ds, randomize=False)
-                    
+
                     # zdata = zipped actual data
                     # cdata = original content data
-                    
+
                     # create reader
                     if with_size:
                         # need object data
                         zdata = zlib.compress(make_object(str_blob_type, cdata))
-                        type, size, reader = DecompressMemMapReader.new(zdata, close_on_deletion)
+                        typ, size, reader = DecompressMemMapReader.new(zdata, close_on_deletion)
                         assert size == len(cdata)
-                        assert type == str_blob_type
-                        
+                        assert typ == str_blob_type
+
                         # even if we don't set the size, it will be set automatically on first read
                         test_reader = DecompressMemMapReader(zdata, close_on_deletion=False)
                         assert test_reader._s == len(cdata)
@@ -95,60 +94,59 @@ def test_decompress_reader(self):
                         zdata = zlib.compress(cdata)
                         reader = DecompressMemMapReader(zdata, close_on_deletion, len(cdata))
                         assert reader._s == len(cdata)
-                    # END get reader 
-                    
+                    # END get reader
+
                     self._assert_stream_reader(reader, cdata, lambda r: r.seek(0))
-                    
+
                     # put in a dummy stream for closing
                     dummy = DummyStream()
                     reader._m = dummy
-                    
+
                     assert not dummy.closed
                     del(reader)
                     assert dummy.closed == close_on_deletion
                 # END for each datasize
             # END whether size should be used
         # END whether stream should be closed when deleted
-        
+
     def test_sha_writer(self):
         writer = Sha1Writer()
-        assert 2 == writer.write("hi")
+        assert 2 == writer.write("hi".encode("ascii"))
         assert len(writer.sha(as_hex=1)) == 40
         assert len(writer.sha(as_hex=0)) == 20
-        
+
         # make sure it does something ;)
         prev_sha = writer.sha()
-        writer.write("hi again")
+        writer.write("hi again".encode("ascii"))
         assert writer.sha() != prev_sha
-        
+
     def test_compressed_writer(self):
         for ds in self.data_sizes:
             fd, path = tempfile.mkstemp()
             ostream = FDCompressedSha1Writer(fd)
             data = make_bytes(ds, randomize=False)
-            
+
             # for now, just a single write, code doesn't care about chunking
             assert len(data) == ostream.write(data)
             ostream.close()
-        
+
             # its closed already
             self.failUnlessRaises(OSError, os.close, fd)
-            
+
             # read everything back, compare to data we zip
             fd = os.open(path, os.O_RDONLY|getattr(os, 'O_BINARY', 0))
             written_data = os.read(fd, os.path.getsize(path))
             assert len(written_data) == os.path.getsize(path)
             os.close(fd)
             assert written_data == zlib.compress(data, 1)   # best speed
-            
+
             os.remove(path)
         # END for each os
-    
+
     def test_decompress_reader_special_case(self):
         odb = LooseObjectDB(fixture_path('objects'))
         ostream = odb.stream(hex_to_bin('7bb839852ed5e3a069966281bb08d50012fb309b'))
-        
+
         # if there is a bug, we will be missing one byte exactly !
         data = ostream.read()
         assert len(data) == ostream.size
-        
diff --git a/gitdb/test/test_util.py b/gitdb/test/test_util.py
index 35f9f44..ec9a86c 100644
--- a/gitdb/test/test_util.py
+++ b/gitdb/test/test_util.py
@@ -5,75 +5,76 @@
 """Test for object db"""
 import tempfile
 import os
+import sys
 
-from lib import TestBase
+from gitdb.test.lib import TestBase
 from gitdb.util import (
-    to_hex_sha, 
-    to_bin_sha, 
-    NULL_HEX_SHA, 
+    to_hex_sha,
+    to_bin_sha,
+    NULL_HEX_SHA,
     LockedFD
-    )
+)
+
 
-    
 class TestUtils(TestBase):
     def test_basics(self):
         assert to_hex_sha(NULL_HEX_SHA) == NULL_HEX_SHA
         assert len(to_bin_sha(NULL_HEX_SHA)) == 20
-        assert to_hex_sha(to_bin_sha(NULL_HEX_SHA)) == NULL_HEX_SHA
-        
+        assert to_hex_sha(to_bin_sha(NULL_HEX_SHA)) == NULL_HEX_SHA.encode("ascii")
+
     def _cmp_contents(self, file_path, data):
-        # raise if data from file at file_path 
+        # raise if data from file at file_path
         # does not match data string
         fp = open(file_path, "rb")
         try:
-            assert fp.read() == data
+            assert fp.read() == data.encode("ascii")
         finally:
             fp.close()
-        
+
     def test_lockedfd(self):
         my_file = tempfile.mktemp()
         orig_data = "hello"
         new_data = "world"
         my_file_fp = open(my_file, "wb")
-        my_file_fp.write(orig_data)
+        my_file_fp.write(orig_data.encode("ascii"))
         my_file_fp.close()
-        
+
         try:
             lfd = LockedFD(my_file)
-            lockfilepath = lfd._lockfilepath() 
-            
+            lockfilepath = lfd._lockfilepath()
+
             # cannot end before it was started
             self.failUnlessRaises(AssertionError, lfd.rollback)
             self.failUnlessRaises(AssertionError, lfd.commit)
-            
+
             # open for writing
             assert not os.path.isfile(lockfilepath)
             wfd = lfd.open(write=True)
             assert lfd._fd is wfd
             assert os.path.isfile(lockfilepath)
-            
+
             # write data and fail
-            os.write(wfd, new_data)
+            os.write(wfd, new_data.encode("ascii"))
             lfd.rollback()
             assert lfd._fd is None
             self._cmp_contents(my_file, orig_data)
             assert not os.path.isfile(lockfilepath)
-            
+
             # additional call doesnt fail
             lfd.commit()
             lfd.rollback()
-            
+
             # test reading
             lfd = LockedFD(my_file)
             rfd = lfd.open(write=False)
-            assert os.read(rfd, len(orig_data)) == orig_data
-            
+            assert os.read(rfd, len(orig_data)) == orig_data.encode("ascii")
+
             assert os.path.isfile(lockfilepath)
             # deletion rolls back
             del(lfd)
             assert not os.path.isfile(lockfilepath)
-            
-            
+
+
             # write data - concurrently
             lfd = LockedFD(my_file)
             olfd = LockedFD(my_file)
@@ -82,17 +83,17 @@ def test_lockedfd(self):
             assert os.path.isfile(lockfilepath)
             # another one fails
             self.failUnlessRaises(IOError, olfd.open)
-            
-            wfdstream.write(new_data)
+
+            wfdstream.write(new_data.encode("ascii"))
             lfd.commit()
             assert not os.path.isfile(lockfilepath)
             self._cmp_contents(my_file, new_data)
-            
+
             # could test automatic _end_writing on destruction
         finally:
             os.remove(my_file)
         # END final cleanup
-        
+
         # try non-existing file for reading
         lfd = LockedFD(tempfile.mktemp())
         try:
@@ -102,4 +103,3 @@ def test_lockedfd(self):
         else:
             self.fail("expected OSError")
         # END handle exceptions
-
diff --git a/gitdb/typ.py b/gitdb/typ.py
index e84dd24..edd1f27 100644
--- a/gitdb/typ.py
+++ b/gitdb/typ.py
@@ -4,11 +4,9 @@
 # the New BSD License: http://www.opensource.org/licenses/bsd-license.php
 """Module containing information about types known to the database"""
 
-#{ String types 
+from gitdb.utils.encoding import force_bytes
 
-str_blob_type = "blob"
-str_commit_type = "commit"
-str_tree_type = "tree"
-str_tag_type = "tag"
-
-#} END string types
+str_blob_type = force_bytes("blob")
+str_commit_type = force_bytes("commit")
+str_tree_type = force_bytes("tree")
+str_tag_type = force_bytes("tag")
diff --git a/gitdb/util.py b/gitdb/util.py
index 1662b66..5a82c55 100644
--- a/gitdb/util.py
+++ b/gitdb/util.py
@@ -8,13 +8,7 @@
 import sys
 import errno
 
-from cStringIO import StringIO
-
-# in py 2.4, StringIO is only StringI, without write support.
-# Hence we must use the python implementation for this
-if sys.version_info[1] < 5:
-    from StringIO import StringIO
-# END handle python 2.4
+from io import StringIO
 
 try:
     import async.mod.zlib as zlib
@@ -24,10 +18,9 @@
 
 from async import ThreadPool
 from smmap import (
-                    StaticWindowMapManager,
-                    SlidingWindowMapManager,
-                    SlidingWindowMapBuffer
-                )
+    StaticWindowMapManager, SlidingWindowMapManager,
+    SlidingWindowMapBuffer
+)
 
 # initialize our global memory manager instance
 # Use it to free cached (and unused) resources.
@@ -37,10 +30,7 @@
     mman = SlidingWindowMapManager()
 #END handle mman
 
-try:
-    import hashlib
-except ImportError:
-    import sha
+import hashlib
 
 try:
     from struct import unpack_from
@@ -60,7 +50,7 @@ def unpack_from(fmt, data, offset=0):
 
 #{ Globals
 
-# A pool distributing tasks, initially with zero threads, hence everything 
+# A pool distributing tasks, initially with zero threads, hence everything
 # will be handled in the main thread
 pool = ThreadPool(0)
 
@@ -91,42 +81,54 @@ def unpack_from(fmt, data, offset=0):
 close = os.close
 fsync = os.fsync
 
-# constants
-NULL_HEX_SHA = "0"*40
-NULL_BIN_SHA = "\0"*20
+# Backwards compatibility imports
+from gitdb.const import NULL_BIN_SHA, NULL_HEX_SHA
 
 #} END Aliases
 
-#{ compatibility stuff ... 
+#{ compatibility stuff ...
 
 class _RandomAccessStringIO(object):
-    """Wrapper to provide required functionality in case memory maps cannot or may 
+    """Wrapper to provide required functionality in case memory maps cannot or may
     not be used. This is only really required in python 2.4"""
     __slots__ = '_sio'
-    
+
     def __init__(self, buf=''):
         self._sio = StringIO(buf)
-        
+
     def __getattr__(self, attr):
         return getattr(self._sio, attr)
-    
+
     def __len__(self):
         return len(self.getvalue())
-        
+
     def __getitem__(self, i):
         return self.getvalue()[i]
-        
+
     def __getslice__(self, start, end):
         return self.getvalue()[start:end]
-    
+
+def byte_ord(b):
+    """
+    Return the integer representation of the byte string.  This supports Python
+    3 byte arrays as well as standard strings.
+    """
+    try:
+        return ord(b)
+    except TypeError:
+        return b
+
 #} END compatibility stuff ...
 
 #{ Routines
 
-def make_sha(source=''):
+def make_sha(source=None):
     """A python2.4 workaround for the sha/hashlib module fiasco
-    
+
     **Note** From the dulwich project """
+    if source is None:
+        source = "".encode("ascii")
+
     try:
         return hashlib.sha1(source)
     except NameError:
@@ -138,25 +140,25 @@ def allocate_memory(size):
     if size == 0:
         return _RandomAccessStringIO('')
     # END handle empty chunks gracefully
-    
+
     try:
         return mmap.mmap(-1, size)  # read-write by default
     except EnvironmentError:
         # setup real memory instead
         # this of course may fail if the amount of memory is not available in
-        # one chunk - would only be the case in python 2.4, being more likely on 
+        # one chunk - would only be the case in python 2.4, being more likely on
         # 32 bit systems.
         return _RandomAccessStringIO("\0"*size)
     # END handle memory allocation
-    
+
 
 def file_contents_ro(fd, stream=False, allow_mmap=True):
     """:return: read-only contents of the file represented by the file descriptor fd
-    
+
     :param fd: file descriptor opened for reading
     :param stream: if False, random access is provided, otherwise the stream interface
         is provided.
-    :param allow_mmap: if True, its allowed to map the contents into memory, which 
+    :param allow_mmap: if True, its allowed to map the contents into memory, which
         allows large files to be handled and accessed efficiently. The file-descriptor
         will change its position if this is False"""
     try:
@@ -171,24 +173,24 @@ def file_contents_ro(fd, stream=False, allow_mmap=True):
     except OSError:
         pass
     # END exception handling
-    
+
     # read manully
     contents = os.read(fd, os.fstat(fd).st_size)
     if stream:
         return _RandomAccessStringIO(contents)
     return contents
-    
+
 def file_contents_ro_filepath(filepath, stream=False, allow_mmap=True, flags=0):
     """Get the file contents at filepath as fast as possible
-    
+
     :return: random access compatible memory of the given filepath
     :param stream: see ``file_contents_ro``
     :param allow_mmap: see ``file_contents_ro``
     :param flags: additional flags to pass to os.open
     :raise OSError: If the file could not be opened
-    
-    **Note** for now we don't try to use O_NOATIME directly as the right value needs to be 
-    shared per database in fact. It only makes a real difference for loose object 
+
+    **Note** for now we don't try to use O_NOATIME directly as the right value needs to be
+    shared per database in fact. It only makes a real difference for loose object
     databases anyway, and they use it with the help of the ``flags`` parameter"""
     fd = os.open(filepath, os.O_RDONLY|getattr(os, 'O_BINARY', 0)|flags)
     try:
@@ -196,19 +198,19 @@ def file_contents_ro_filepath(filepath, stream=False, allow_mmap=True, flags=0):
     finally:
         close(fd)
     # END assure file is closed
-    
+
 def sliding_ro_buffer(filepath, flags=0):
     """
     :return: a buffer compatible object which uses our mapped memory manager internally
         ready to read the whole given filepath"""
     return SlidingWindowMapBuffer(mman.make_cursor(filepath), flags=flags)
-    
+
 def to_hex_sha(sha):
     """:return: hexified version  of sha"""
     if len(sha) == 40:
         return sha
     return bin_to_hex(sha)
-    
+
 def to_bin_sha(sha):
     if len(sha) == 20:
         return sha
@@ -227,12 +229,12 @@ class LazyMixin(object):
     is actually accessed and retrieved the first time. All future accesses will
     return the cached value as stored in the Instance's dict or slot.
     """
-    
+
     __slots__ = tuple()
-    
+
     def __getattr__(self, attr):
         """
-        Whenever an attribute is requested that we do not know, we allow it 
+        Whenever an attribute is requested that we do not know, we allow it
         to be created and set. Next time the same attribute is reqeusted, it is simply
         returned from our dict/slots. """
         self._set_cache_(attr)
@@ -241,70 +243,70 @@ def __getattr__(self, attr):
 
     def _set_cache_(self, attr):
         """
-        This method should be overridden in the derived class. 
+        This method should be overridden in the derived class.
         It should check whether the attribute named by attr can be created
         and cached. Do nothing if you do not know the attribute or call your subclass
-        
-        The derived class may create as many additional attributes as it deems 
-        necessary in case a git command returns more information than represented 
+
+        The derived class may create as many additional attributes as it deems
+        necessary in case a git command returns more information than represented
         in the single attribute."""
         pass
 
-    
+
 class LockedFD(object):
     """
     This class facilitates a safe read and write operation to a file on disk.
-    If we write to 'file', we obtain a lock file at 'file.lock' and write to 
-    that instead. If we succeed, the lock file will be renamed to overwrite 
+    If we write to 'file', we obtain a lock file at 'file.lock' and write to
+    that instead. If we succeed, the lock file will be renamed to overwrite
     the original file.
-    
-    When reading, we obtain a lock file, but to prevent other writers from 
+
+    When reading, we obtain a lock file, but to prevent other writers from
     succeeding while we are reading the file.
-    
-    This type handles error correctly in that it will assure a consistent state 
+
+    This type handles error correctly in that it will assure a consistent state
     on destruction.
-    
+
     **note** with this setup, parallel reading is not possible"""
     __slots__ = ("_filepath", '_fd', '_write')
-    
+
     def __init__(self, filepath):
         """Initialize an instance with the givne filepath"""
         self._filepath = filepath
         self._fd = None
         self._write = None          # if True, we write a file
-    
+
     def __del__(self):
         # will do nothing if the file descriptor is already closed
         if self._fd is not None:
             self.rollback()
-        
+
     def _lockfilepath(self):
         return "%s.lock" % self._filepath
-        
+
     def open(self, write=False, stream=False):
         """
         Open the file descriptor for reading or writing, both in binary mode.
-        
+
         :param write: if True, the file descriptor will be opened for writing. Other
             wise it will be opened read-only.
-        :param stream: if True, the file descriptor will be wrapped into a simple stream 
+        :param stream: if True, the file descriptor will be wrapped into a simple stream
             object which supports only reading or writing
         :return: fd to read from or write to. It is still maintained by this instance
             and must not be closed directly
         :raise IOError: if the lock could not be retrieved
         :raise OSError: If the actual file could not be opened for reading
-        
+
         **note** must only be called once"""
         if self._write is not None:
             raise AssertionError("Called %s multiple times" % self.open)
-        
+
         self._write = write
-        
+
         # try to open the lock file
         binary = getattr(os, 'O_BINARY', 0)
         lockmode =  os.O_WRONLY | os.O_CREAT | os.O_EXCL | binary
         try:
-            fd = os.open(self._lockfilepath(), lockmode, 0600)
+            fd = os.open(self._lockfilepath(), lockmode, int("600", 8))
             if not write:
                 os.close(fd)
             else:
@@ -313,7 +315,7 @@ def open(self, write=False, stream=False):
         except OSError:
             raise IOError("Lock at %r could not be obtained" % self._lockfilepath())
         # END handle lock retrieval
-        
+
         # open actual file if required
         if self._fd is None:
             # we could specify exlusive here, as we obtained the lock anyway
@@ -325,41 +327,41 @@ def open(self, write=False, stream=False):
                 raise
             # END handle lockfile
         # END open descriptor for reading
-        
+
         if stream:
             # need delayed import
-            from stream import FDStream
+            from gitdb.stream import FDStream
             return FDStream(self._fd)
         else:
             return self._fd
         # END handle stream
-        
+
     def commit(self):
-        """When done writing, call this function to commit your changes into the 
-        actual file. 
+        """When done writing, call this function to commit your changes into the
+        actual file.
         The file descriptor will be closed, and the lockfile handled.
-        
+
         **Note** can be called multiple times"""
         self._end_writing(successful=True)
-        
+
     def rollback(self):
-        """Abort your operation without any changes. The file descriptor will be 
+        """Abort your operation without any changes. The file descriptor will be
         closed, and the lock released.
-        
+
         **Note** can be called multiple times"""
         self._end_writing(successful=False)
-        
+
     def _end_writing(self, successful=True):
         """Handle the lock according to the write mode """
         if self._write is None:
             raise AssertionError("Cannot end operation if it wasn't started yet")
-        
+
         if self._fd is None:
             return
-        
+
         os.close(self._fd)
         self._fd = None
-        
+
         lockfile = self._lockfilepath()
         if self._write and successful:
             # on windows, rename does not silently overwrite the existing one
@@ -369,11 +371,11 @@ def _end_writing(self, successful=True):
                 # END remove if exists
             # END win32 special handling
             os.rename(lockfile, self._filepath)
-            
+
             # assure others can at least read the file - the tmpfile left it at rw--
             # We may also write that file, on windows that boils down to a remove-
             # protection as well
-            chmod(self._filepath, 0644)
+            chmod(self._filepath, int("644", 8))
         else:
             # just delete the file so far, we failed
             os.remove(lockfile)
diff --git a/gitdb/utils/__init__.py b/gitdb/utils/__init__.py
new file mode 100644
index 0000000..e69de29
diff --git a/gitdb/utils/compat.py b/gitdb/utils/compat.py
new file mode 100644
index 0000000..b9da683
--- /dev/null
+++ b/gitdb/utils/compat.py
@@ -0,0 +1,39 @@
+import sys
+
+PY3 = sys.version_info[0] == 3
+
+try:
+    from itertools import izip
+except ImportError:
+    izip = zip
+
+try:
+    # Python 2
+    buffer = buffer
+    memoryview = buffer
+except NameError:
+    # Python 3 has no `buffer`; only `memoryview`
+    def buffer(obj, offset, size=None):
+        if size is None:
+            return memoryview(obj)[offset:]
+        else:
+            return memoryview(obj[offset:offset+size])
+
+    memoryview = memoryview
+
+if PY3:
+    MAXSIZE = sys.maxsize
+else:
+    # It's possible to have sizeof(long) != sizeof(Py_ssize_t).
+    class X(object):
+        def __len__(self):
+            return 1 << 31
+    try:
+        len(X())
+    except OverflowError:
+        # 32-bit
+        MAXSIZE = int((1 << 31) - 1)
+    else:
+        # 64-bit
+        MAXSIZE = int((1 << 63) - 1)
+    del X
diff --git a/gitdb/utils/encoding.py b/gitdb/utils/encoding.py
new file mode 100644
index 0000000..12164e7
--- /dev/null
+++ b/gitdb/utils/encoding.py
@@ -0,0 +1,35 @@
+from gitdb.utils import compat
+
+if compat.PY3:
+    string_types = (str, )
+    text_type = str
+else:
+    string_types = (basestring, )
+    text_type = unicode
+
+def force_bytes(data, encoding="utf-8"):
+    if isinstance(data, bytes):
+        return data
+
+    if isinstance(data, compat.memoryview):
+        return bytes(data)
+
+    if isinstance(data, string_types):
+        return data.encode(encoding)
+
+    return data
+
+def force_text(data, encoding="utf-8"):
+    if isinstance(data, text_type):
+        return data
+
+    if isinstance(data, string_types):
+        return data.decode(encoding)
+
+    if not isinstance(data, bytes):
+        data = force_bytes(data, encoding)
+
+    if compat.PY3:
+        return text_type(data, encoding)
+    else:
+        return text_type(data)