尝试使用 ctypes 调用 wincred api

我正在尝试使用 ctypes API 读取 Windows 凭证库，但我不确定如何将函数结果转换回可用的 ctypes.Structure。

import ctypes
class CREDENTIALS(ctypes.Structure):
    _fields_ = [
        ("Flags", ctypes.c_int),
        ("Type", ctypes.c_int),
        ("TargetName", ctypes.c_wchar_p),
        ("Comment", ctypes.c_wchar_p),
        ("CredentialBlobSize", ctypes.c_int),
        ("CredentialBlob", ctypes.c_wchar_p),
        ("AttributeCount", ctypes.c_int),
        ("Attributes", ctypes.c_wchar_p),
        ("TargetAlias", ctypes.c_wchar_p),
        ("UserName", ctypes.c_wchar_p)
]
advapi32 = ctypes.oledll.LoadLibrary('Advapi32.dll')
advapi32.CredReadW.restype = ctypes.c_bool
advapi32.CredReadW.argtypes = [ctypes.c_wchar_p, ctypes.c_int, ctypes.c_int, ctypes.POINTER(CREDENTIALS)]
target = "login.example.com"
pcred = ctypes.pointer(CREDENTIALS())
ok = advapi32.CredReadW(target,1,0,pcred)
cred = pcred.contents
print ok, pcred, cred.UserName, cred.CredentialBlob

Result:

1 <__main__.LP_CREDENTIALS object at 0x012CECB0> None None

该函数返回 true ，因此它可以工作，但指针内容似乎为空。我究竟做错了什么？

oledll应该windll. oledll用于返回的函数HRESULT.

的定义CREDENTIAL缺少一些字段（LastWritten and Persist）。定义 （link http://msdn.microsoft.com/en-us/library/windows/desktop/aa374788(v=vs.85).aspx) is:

typedef struct _CREDENTIAL {
  DWORD                 Flags;
  DWORD                 Type;
  LPTSTR                TargetName;
  LPTSTR                Comment;
  FILETIME              LastWritten;
  DWORD                 CredentialBlobSize;
  LPBYTE                CredentialBlob;
  DWORD                 Persist;
  DWORD                 AttributeCount;
  PCREDENTIAL_ATTRIBUTE Attributes;
  LPTSTR                TargetAlias;
  LPTSTR                UserName;
} CREDENTIAL, *PCREDENTIAL;