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1import unittest
2from test import support
3from ctypes import *
4
5import _ctypes_test
6
7lib = CDLL(_ctypes_test.__file__)
8
9class StringPtrTestCase(unittest.TestCase):
10
11    @support.refcount_test
12    def test__POINTER_c_char(self):
13        class X(Structure):
14            _fields_ = [("str", POINTER(c_char))]
15        x = X()
16
17        # NULL pointer access
18        self.assertRaises(ValueError, getattr, x.str, "contents")
19        b = c_buffer(b"Hello, World")
20        from sys import getrefcount as grc
21        self.assertEqual(grc(b), 2)
22        x.str = b
23        self.assertEqual(grc(b), 3)
24
25        # POINTER(c_char) and Python string is NOT compatible
26        # POINTER(c_char) and c_buffer() is compatible
27        for i in range(len(b)):
28            self.assertEqual(b[i], x.str[i])
29
30        self.assertRaises(TypeError, setattr, x, "str", "Hello, World")
31
32    def test__c_char_p(self):
33        class X(Structure):
34            _fields_ = [("str", c_char_p)]
35        x = X()
36
37        # c_char_p and Python string is compatible
38        # c_char_p and c_buffer is NOT compatible
39        self.assertEqual(x.str, None)
40        x.str = b"Hello, World"
41        self.assertEqual(x.str, b"Hello, World")
42        b = c_buffer(b"Hello, World")
43        self.assertRaises(TypeError, setattr, x, b"str", b)
44
45
46    def test_functions(self):
47        strchr = lib.my_strchr
48        strchr.restype = c_char_p
49
50        # c_char_p and Python string is compatible
51        # c_char_p and c_buffer are now compatible
52        strchr.argtypes = c_char_p, c_char
53        self.assertEqual(strchr(b"abcdef", b"c"), b"cdef")
54        self.assertEqual(strchr(c_buffer(b"abcdef"), b"c"), b"cdef")
55
56        # POINTER(c_char) and Python string is NOT compatible
57        # POINTER(c_char) and c_buffer() is compatible
58        strchr.argtypes = POINTER(c_char), c_char
59        buf = c_buffer(b"abcdef")
60        self.assertEqual(strchr(buf, b"c"), b"cdef")
61        self.assertEqual(strchr(b"abcdef", b"c"), b"cdef")
62
63        # XXX These calls are dangerous, because the first argument
64        # to strchr is no longer valid after the function returns!
65        # So we must keep a reference to buf separately
66
67        strchr.restype = POINTER(c_char)
68        buf = c_buffer(b"abcdef")
69        r = strchr(buf, b"c")
70        x = r[0], r[1], r[2], r[3], r[4]
71        self.assertEqual(x, (b"c", b"d", b"e", b"f", b"\000"))
72        del buf
73        # Because r is a pointer to memory that is freed after deleting buf,
74        # the pointer is hanging and using it would reference freed memory.
75
76if __name__ == '__main__':
77    unittest.main()
78