python - readlink () 함수를 구현하는 데 문제가 있습니다

ERROR_MOD_NOT_FOUND  (126)은 windll.CloseHandle(hfile) 로 인한 것 같습니다 "closehandle.dll"를로드하려고합니다. kernel32 가 없습니다 .

다음은 정션 및 심볼릭 링크를 처리하는 대체 구현입니다.

타입 정의

import ctypes
from ctypes import wintypes
kernel32 = ctypes.WinDLL('kernel32', use_last_error=True)
FILE_READ_ATTRIBUTES = 0x0080
OPEN_EXISTING = 3
FILE_FLAG_OPEN_REPARSE_POINT = 0x00200000
FILE_FLAG_BACKUP_SEMANTICS   = 0x02000000
FILE_ATTRIBUTE_REPARSE_POINT = 0x0400
IO_REPARSE_TAG_MOUNT_POINT = 0xA0000003
IO_REPARSE_TAG_SYMLINK     = 0xA000000C
FSCTL_GET_REPARSE_POINT    = 0x000900A8
MAXIMUM_REPARSE_DATA_BUFFER_SIZE = 0x4000
LPDWORD = ctypes.POINTER(wintypes.DWORD)
LPWIN32_FIND_DATA = ctypes.POINTER(wintypes.WIN32_FIND_DATAW)
INVALID_HANDLE_VALUE = wintypes.HANDLE(-1).value
def IsReparseTagNameSurrogate(tag):
    return bool(tag & 0x20000000)
def _check_invalid_handle(result, func, args):
    if result == INVALID_HANDLE_VALUE:
        raise ctypes.WinError(ctypes.get_last_error())
    return args
def _check_bool(result, func, args):
    if not result:
        raise ctypes.WinError(ctypes.get_last_error())
    return args
kernel32.FindFirstFileW.errcheck = _check_invalid_handle
kernel32.FindFirstFileW.restype = wintypes.HANDLE
kernel32.FindFirstFileW.argtypes = (
    wintypes.LPCWSTR,  # _In_  lpFileName
    LPWIN32_FIND_DATA) # _Out_ lpFindFileData
kernel32.FindClose.argtypes = (
    wintypes.HANDLE,) # _Inout_ hFindFile
kernel32.CreateFileW.errcheck = _check_invalid_handle
kernel32.CreateFileW.restype = wintypes.HANDLE
kernel32.CreateFileW.argtypes = (
    wintypes.LPCWSTR, # _In_     lpFileName
    wintypes.DWORD,   # _In_     dwDesiredAccess
    wintypes.DWORD,   # _In_     dwShareMode
    wintypes.LPVOID,  # _In_opt_ lpSecurityAttributes
    wintypes.DWORD,   # _In_     dwCreationDisposition
    wintypes.DWORD,   # _In_     dwFlagsAndAttributes
    wintypes.HANDLE)  # _In_opt_ hTemplateFile 
kernel32.CloseHandle.argtypes = (
    wintypes.HANDLE,) # _In_ hObject
kernel32.DeviceIoControl.errcheck = _check_bool
kernel32.DeviceIoControl.argtypes = (
    wintypes.HANDLE,  # _In_        hDevice
    wintypes.DWORD,   # _In_        dwIoControlCode
    wintypes.LPVOID,  # _In_opt_    lpInBuffer
    wintypes.DWORD,   # _In_        nInBufferSize
    wintypes.LPVOID,  # _Out_opt_   lpOutBuffer
    wintypes.DWORD,   # _In_        nOutBufferSize
    LPDWORD,          # _Out_opt_   lpBytesReturned
    wintypes.LPVOID)  # _Inout_opt_ lpOverlapped 
class REPARSE_DATA_BUFFER(ctypes.Structure):
    class ReparseData(ctypes.Union):
        class LinkData(ctypes.Structure):
            _fields_ = (('SubstituteNameOffset', wintypes.USHORT),
                        ('SubstituteNameLength', wintypes.USHORT),
                        ('PrintNameOffset',      wintypes.USHORT),
                        ('PrintNameLength',      wintypes.USHORT))
            @property
            def PrintName(self):
                dt = wintypes.WCHAR * (self.PrintNameLength //
                                       ctypes.sizeof(wintypes.WCHAR))
                name = dt.from_address(ctypes.addressof(self.PathBuffer) +
                                       self.PrintNameOffset).value
                if name.startswith(r'\??'):
                    name = r'\\?' + name[3:] # NT => Windows
                return name
        class SymbolicLinkData(LinkData):
            _fields_ = (('Flags',      wintypes.ULONG),
                        ('PathBuffer', wintypes.BYTE * 0))
        class MountPointData(LinkData):
            _fields_ = (('PathBuffer', wintypes.BYTE * 0),)
        class GenericData(ctypes.Structure):
            _fields_ = (('DataBuffer', wintypes.BYTE * 0),)
        _fields_ = (('SymbolicLinkReparseBuffer', SymbolicLinkData),
                    ('MountPointReparseBuffer',   MountPointData),
                    ('GenericReparseBuffer',      GenericData))
    _fields_ = (('ReparseTag',        wintypes.ULONG),
                ('ReparseDataLength', wintypes.USHORT),
                ('Reserved',          wintypes.USHORT),
                ('ReparseData',       ReparseData))
    _anonymous_ = ('ReparseData',)

기능

def islink(path):
    data = wintypes.WIN32_FIND_DATAW()
    kernel32.FindClose(kernel32.FindFirstFileW(path, ctypes.byref(data)))
    if not data.dwFileAttributes & FILE_ATTRIBUTE_REPARSE_POINT:
        return False
    return IsReparseTagNameSurrogate(data.dwReserved0)
def readlink(path):
    n = wintypes.DWORD()
    buf = (wintypes.BYTE * MAXIMUM_REPARSE_DATA_BUFFER_SIZE)()
    flags = FILE_FLAG_OPEN_REPARSE_POINT | FILE_FLAG_BACKUP_SEMANTICS
    handle = kernel32.CreateFileW(path, FILE_READ_ATTRIBUTES, 0, None,
                OPEN_EXISTING, flags, None)
    try:
        kernel32.DeviceIoControl(handle, FSCTL_GET_REPARSE_POINT, None, 0,
            buf, ctypes.sizeof(buf), ctypes.byref(n), None)
    finally:
        kernel32.CloseHandle(handle)
    rb = REPARSE_DATA_BUFFER.from_buffer(buf)
    tag = rb.ReparseTag
    if tag == IO_REPARSE_TAG_SYMLINK:
        return rb.SymbolicLinkReparseBuffer.PrintName
    if tag == IO_REPARSE_TAG_MOUNT_POINT:
        return rb.MountPointReparseBuffer.PrintName
    if not IsReparseTagNameSurrogate(tag):
        raise ValueError("not a link")
    raise ValueError("unsupported reparse tag: %d" % tag)

예

>>> sys.version
'2.7.13 (v2.7.13:a06454b1afa1, Dec 17 2016, 20:53:40) 
[MSC v.1500 64 bit (AMD64)]'
>>> os.system(r'mklink /d spam C:\Windows')
symbolic link created for spam <<===>> C:\Windows
0
>>> islink('spam')
True
>>> readlink('spam')
u'C:\\Windows'
>>> islink('C:/Documents and Settings') # junction
True
>>> readlink('C:/Documents and Settings')
u'C:\\Users'
>>> islink('C:/Users/All Users') # symlinkd
True
>>> readlink('C:/Users/All Users')
u'C:\\ProgramData'

이것은 Tcl에서 file readlink 로 구현됩니다.  그리고 약간의 차이가있는 것처럼 보이기 때문에 이것을 읽을 가치가 있습니다. 와이즈 비즈  함수 호출 WinReadLinkDirectory   NativeReadReparse 를 읽으려면  그러나 이것은 REPARSE_DATA_BUFFER 에 다른 플래그를 사용합니다.  기능. 또한 버퍼 크기가 다르다고 생각하며 Win32 호출의 구조 크기는 종종 사용되는 API 버전을 감지하는 데 사용되므로 크기를 올바른 값 (또는 가능한 동일한 값)으로 설정하는 것이 좋습니다 Tcl 구현))

Tcl 지원에 대한 의미를 보여 드리기 위해 :

CreateFile