import unittest
from ctypes import *

libc = None
import os, sys
if os.name == "nt":
    libc = cdll.msvcrt
    
elif os.name == "posix":
    if sys.platform == "darwin":
        libc = cdll.LoadLibrary("/usr/lib/libc.dylib")
    elif sys.platform == "cygwin":
        libc = cdll.LoadLibrary("/bin/cygwin1.dll")
    elif sys.platform == "sunos5":
        libc = cdll.LoadLibrary("/lib/libc.so")
    else:
        try:
            libc = cdll.LoadLibrary("/lib/libc.so.6")
        except OSError:
            libc = None

class StringPtrTestCase(unittest.TestCase):

    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 = c_buffer("Hello, World")
        from sys import getrefcount as grc
        self.failUnlessEqual(grc(b), 2)
        x.str = b
        self.failUnlessEqual(grc(b), 3)

        # POINTER(c_char) and Python string is NOT compatible
        # POINTER(c_char) and c_buffer() is compatible
        for i in range(len(b)):
            self.failUnlessEqual(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 c_buffer is NOT compatible
        self.failUnlessEqual(x.str, None)
        x.str = "Hello, World"
        self.failUnlessEqual(x.str, "Hello, World")
        b = c_buffer("Hello, World")
        self.failUnlessRaises(TypeError, setattr, x, "str", b)


    if libc is not None:
        def test_functions(self):
            strchr = libc.strchr
            strchr.restype = c_char_p

            # c_char_p and Python string is compatible
            # c_char_p and c_buffer are now compatible
            strchr.argtypes = c_char_p, c_char
            self.failUnlessEqual(strchr("abcdef", "c"), "cdef")
            self.failUnlessEqual(strchr(c_buffer("abcdef"), "c"), "cdef")

            # POINTER(c_char) and Python string is NOT compatible
            # POINTER(c_char) and c_buffer() is compatible
            strchr.argtypes = POINTER(c_char), c_char
            buf = c_buffer("abcdef")
            self.failUnlessEqual(strchr(buf, "c"), "cdef")
            self.failUnlessEqual(strchr("abcdef", "c"), "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 = c_buffer("abcdef")
            r = strchr(buf, "c")
            x = r[0], r[1], r[2], r[3], r[4]
            self.failUnlessEqual(x, ("c", "d", "e", "f", "\000"))
            del buf
            # x1 will NOT be the same as x, usually:
            x1 = r[0], r[1], r[2], r[3], r[4]

if __name__ == '__main__':
    unittest.main()