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test_stringptr.py
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81 lines (64 loc) · 2.83 KB
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import sys
import unittest
from test import support
from ctypes import (CDLL, Structure, POINTER, create_string_buffer,
c_char, c_char_p)
from test.support import import_helper
_ctypes_test = import_helper.import_module("_ctypes_test")
lib = CDLL(_ctypes_test.__file__)
class StringPtrTestCase(unittest.TestCase):
@support.refcount_test
def test__POINTER_c_char(self):
class X(Structure):
_fields_ = [("str", POINTER(c_char))]
x = X()
# NULL pointer access
self.assertRaises(ValueError, getattr, x.str, "contents")
b = create_string_buffer(b"Hello, World")
orig_refcount = sys.getrefcount(b)
x.str = b
self.assertEqual(sys.getrefcount(b), orig_refcount + 1)
# POINTER(c_char) and Python string is NOT compatible
# POINTER(c_char) and create_string_buffer() is compatible
for i in range(len(b)):
self.assertEqual(b[i], x.str[i])
self.assertRaises(TypeError, setattr, x, "str", "Hello, World")
def test__c_char_p(self):
class X(Structure):
_fields_ = [("str", c_char_p)]
x = X()
# c_char_p and Python string is compatible
# c_char_p and create_string_buffer is NOT compatible
self.assertEqual(x.str, None)
x.str = b"Hello, World"
self.assertEqual(x.str, b"Hello, World")
b = create_string_buffer(b"Hello, World")
self.assertRaises(TypeError, setattr, x, b"str", b)
def test_functions(self):
strchr = lib.my_strchr
strchr.restype = c_char_p
# c_char_p and Python string is compatible
# c_char_p and create_string_buffer are now compatible
strchr.argtypes = c_char_p, c_char
self.assertEqual(strchr(b"abcdef", b"c"), b"cdef")
self.assertEqual(strchr(create_string_buffer(b"abcdef"), b"c"),
b"cdef")
# POINTER(c_char) and Python string is NOT compatible
# POINTER(c_char) and create_string_buffer() is compatible
strchr.argtypes = POINTER(c_char), c_char
buf = create_string_buffer(b"abcdef")
self.assertEqual(strchr(buf, b"c"), b"cdef")
self.assertEqual(strchr(b"abcdef", b"c"), b"cdef")
# XXX These calls are dangerous, because the first argument
# to strchr is no longer valid after the function returns!
# So we must keep a reference to buf separately
strchr.restype = POINTER(c_char)
buf = create_string_buffer(b"abcdef")
r = strchr(buf, b"c")
x = r[0], r[1], r[2], r[3], r[4]
self.assertEqual(x, (b"c", b"d", b"e", b"f", b"\000"))
del buf
# Because r is a pointer to memory that is freed after deleting buf,
# the pointer is hanging and using it would reference freed memory.
if __name__ == '__main__':
unittest.main()