python
diff --git a/‎Lib/gzip.py
Lines changed: 111 additions & 0 deletions b/‎Lib/gzip.py
Lines changed: 111 additions & 0 deletions
@@ -9,7 +9,9 @@
 import zlib
 import builtins
 import io
+import _pyio as pyio
 import _compression
+import errno
 
 __all__ = ["BadGzipFile", "GzipFile", "open", "compress", "decompress"]
 
@@ -445,6 +447,115 @@ def _read_gzip_header(fp):
         _read_exact(fp, 2)     # Read & discard the 16-bit header CRC
     return last_mtime
 
+class _Writable():
+    def writable(self):
+        return True
+
+class GzipWriter(pyio.BufferedWriter):
+    def __init__(self, fp, compresslevel=_COMPRESS_LEVEL_BEST, buffer_size=pyio.DEFAULT_BUFFER_SIZE, mtime=None):
+        super().__init__(fp, buffer_size=buffer_size)
+
+        self.fileobj = fp
+        self.crc = zlib.crc32(b"")
+        self.size = 0
+        self.writebuf = []
+        self.bufsize = 0
+        self.offset = 0  # Current file offset for seek(), tell(), etc
+        self.compress = zlib.compressobj(compresslevel,
+                                         zlib.DEFLATED,
+                                         -zlib.MAX_WBITS,
+                                         zlib.DEF_MEM_LEVEL,
+                                         0)
+        self._write_mtime = mtime
+
+        self._write_gzip_header(compresslevel)
+
+    def close(self):
+        fileobj = self.fileobj
+        self.flush()
+        fileobj.write(self.compress.flush())
+        write32u(fileobj, self.crc)
+        # self.size may exceed 2 GiB, or even 4 GiB
+        write32u(fileobj, self.size & 0xffffffff)
+        self.fileobj.close()
+
+    def write(self, data):
+        super().write(data)
+
+    def _flush_unlocked(self):
+        if self.closed:
+            raise ValueError("flush on closed file")
+        while self._write_buf:
+            try:
+                #n = self.raw.write(self._write_buf)
+                n = self.compress_and_write(self._write_buf)
+            except BlockingIOError:
+                raise RuntimeError("self.raw should implement RawIOBase: it "
+                                   "should not raise BlockingIOError")
+            if n is None:
+                raise BlockingIOError(
+                    errno.EAGAIN,
+                    "write could not complete without blocking", 0)
+            if n > len(self._write_buf) or n < 0:
+                raise OSError("write() returned incorrect number of bytes")
+            del self._write_buf[:n]
+
+    def compress_and_write(self,data):
+        self._check_not_closed()
+        if self.fileobj is None:
+            raise ValueError("write() on closed GzipFile object")
+
+        if isinstance(data, (bytes, bytearray)):
+            length = len(data)
+        else:
+            # accept any data that supports the buffer protocol
+            data = memoryview(data)
+            length = data.nbytes
+
+        if length > 0:
+            self.fileobj.write(self.compress.compress(data))
+            self.size += length
+            self.crc = zlib.crc32(data, self.crc)
+            self.offset += length
+
+        return length
+
+    def _write_gzip_header(self, compresslevel):
+        self.fileobj.write(b'\037\213')             # magic header
+        self.fileobj.write(b'\010')                 # compression method
+        try:
+            # RFC 1952 requires the FNAME field to be Latin-1. Do not
+            # include filenames that cannot be represented that way.
+            fname = os.path.basename(self.name)
+            if not isinstance(fname, bytes):
+                fname = fname.encode('latin-1')
+            if fname.endswith(b'.gz'):
+                fname = fname[:-3]
+        except UnicodeEncodeError:
+            fname = b''
+        flags = 0
+        if fname:
+            flags = FNAME
+        self.fileobj.write(chr(flags).encode('latin-1'))
+        mtime = self._write_mtime
+        if mtime is None:
+            mtime = time.time()
+        write32u(self.fileobj, int(mtime))
+        if compresslevel == _COMPRESS_LEVEL_BEST:
+            xfl = b'\002'
+        elif compresslevel == _COMPRESS_LEVEL_FAST:
+            xfl = b'\004'
+        else:
+            xfl = b'\000'
+        self.fileobj.write(xfl)
+        self.fileobj.write(b'\377')
+        if fname:
+            self.fileobj.write(fname + b'\000')
+
+    def _check_not_closed(self):
+        return self.fileobj.closed
+
+
 
 class _GzipReader(_compression.DecompressReader):
     def __init__(self, fp):