1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
|
# -*- coding:utf-8 -*-
#
# Copyright (C) 2016 The Android Open Source Project
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import errno
from pyversion import is_python3
from ctypes import WinDLL, get_last_error, FormatError, WinError, addressof
from ctypes import c_buffer
from ctypes.wintypes import BOOL, BOOLEAN, LPCWSTR, DWORD, HANDLE
from ctypes.wintypes import WCHAR, USHORT, LPVOID, ULONG
if is_python3():
from ctypes import c_ubyte, Structure, Union, byref
from ctypes.wintypes import LPDWORD
else:
# For legacy Python2 different imports are needed.
from ctypes.wintypes import POINTER, c_ubyte, Structure, Union, byref
LPDWORD = POINTER(DWORD)
kernel32 = WinDLL('kernel32', use_last_error=True)
UCHAR = c_ubyte
# Win32 error codes
ERROR_SUCCESS = 0
ERROR_NOT_SUPPORTED = 50
ERROR_PRIVILEGE_NOT_HELD = 1314
# Win32 API entry points
CreateSymbolicLinkW = kernel32.CreateSymbolicLinkW
CreateSymbolicLinkW.restype = BOOLEAN
CreateSymbolicLinkW.argtypes = (LPCWSTR, # lpSymlinkFileName In
LPCWSTR, # lpTargetFileName In
DWORD) # dwFlags In
# Symbolic link creation flags
SYMBOLIC_LINK_FLAG_FILE = 0x00
SYMBOLIC_LINK_FLAG_DIRECTORY = 0x01
# symlink support for CreateSymbolicLink() starting with Windows 10 (1703, v10.0.14972)
SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE = 0x02
GetFileAttributesW = kernel32.GetFileAttributesW
GetFileAttributesW.restype = DWORD
GetFileAttributesW.argtypes = (LPCWSTR,) # lpFileName In
INVALID_FILE_ATTRIBUTES = 0xFFFFFFFF
FILE_ATTRIBUTE_REPARSE_POINT = 0x00400
CreateFileW = kernel32.CreateFileW
CreateFileW.restype = HANDLE
CreateFileW.argtypes = (LPCWSTR, # lpFileName In
DWORD, # dwDesiredAccess In
DWORD, # dwShareMode In
LPVOID, # lpSecurityAttributes In_opt
DWORD, # dwCreationDisposition In
DWORD, # dwFlagsAndAttributes In
HANDLE) # hTemplateFile In_opt
CloseHandle = kernel32.CloseHandle
CloseHandle.restype = BOOL
CloseHandle.argtypes = (HANDLE,) # hObject In
INVALID_HANDLE_VALUE = HANDLE(-1).value
OPEN_EXISTING = 3
FILE_FLAG_BACKUP_SEMANTICS = 0x02000000
FILE_FLAG_OPEN_REPARSE_POINT = 0x00200000
DeviceIoControl = kernel32.DeviceIoControl
DeviceIoControl.restype = BOOL
DeviceIoControl.argtypes = (HANDLE, # hDevice In
DWORD, # dwIoControlCode In
LPVOID, # lpInBuffer In_opt
DWORD, # nInBufferSize In
LPVOID, # lpOutBuffer Out_opt
DWORD, # nOutBufferSize In
LPDWORD, # lpBytesReturned Out_opt
LPVOID) # lpOverlapped Inout_opt
# Device I/O control flags and options
FSCTL_GET_REPARSE_POINT = 0x000900A8
IO_REPARSE_TAG_MOUNT_POINT = 0xA0000003
IO_REPARSE_TAG_SYMLINK = 0xA000000C
MAXIMUM_REPARSE_DATA_BUFFER_SIZE = 0x4000
class GENERIC_REPARSE_BUFFER(Structure):
_fields_ = (('DataBuffer', UCHAR * 1),)
class SYMBOLIC_LINK_REPARSE_BUFFER(Structure):
_fields_ = (('SubstituteNameOffset', USHORT),
('SubstituteNameLength', USHORT),
('PrintNameOffset', USHORT),
('PrintNameLength', USHORT),
('Flags', ULONG),
('PathBuffer', WCHAR * 1))
@property
def PrintName(self):
arrayt = WCHAR * (self.PrintNameLength // 2)
offset = type(self).PathBuffer.offset + self.PrintNameOffset
return arrayt.from_address(addressof(self) + offset).value
class MOUNT_POINT_REPARSE_BUFFER(Structure):
_fields_ = (('SubstituteNameOffset', USHORT),
('SubstituteNameLength', USHORT),
('PrintNameOffset', USHORT),
('PrintNameLength', USHORT),
('PathBuffer', WCHAR * 1))
@property
def PrintName(self):
arrayt = WCHAR * (self.PrintNameLength // 2)
offset = type(self).PathBuffer.offset + self.PrintNameOffset
return arrayt.from_address(addressof(self) + offset).value
class REPARSE_DATA_BUFFER(Structure):
class REPARSE_BUFFER(Union):
_fields_ = (('SymbolicLinkReparseBuffer', SYMBOLIC_LINK_REPARSE_BUFFER),
('MountPointReparseBuffer', MOUNT_POINT_REPARSE_BUFFER),
('GenericReparseBuffer', GENERIC_REPARSE_BUFFER))
_fields_ = (('ReparseTag', ULONG),
('ReparseDataLength', USHORT),
('Reserved', USHORT),
('ReparseBuffer', REPARSE_BUFFER))
_anonymous_ = ('ReparseBuffer',)
def create_filesymlink(source, link_name):
"""Creates a Windows file symbolic link source pointing to link_name."""
_create_symlink(source, link_name, SYMBOLIC_LINK_FLAG_FILE)
def create_dirsymlink(source, link_name):
"""Creates a Windows directory symbolic link source pointing to link_name.
"""
_create_symlink(source, link_name, SYMBOLIC_LINK_FLAG_DIRECTORY)
def _create_symlink(source, link_name, dwFlags):
if not CreateSymbolicLinkW(link_name, source,
dwFlags | SYMBOLIC_LINK_FLAG_ALLOW_UNPRIVILEGED_CREATE):
# See https://github.com/golang/go/pull/24307/files#diff-b87bc12e4da2497308f9ef746086e4f0
# "the unprivileged create flag is unsupported below Windows 10 (1703, v10.0.14972).
# retry without it."
if not CreateSymbolicLinkW(link_name, source, dwFlags):
code = get_last_error()
error_desc = FormatError(code).strip()
if code == ERROR_PRIVILEGE_NOT_HELD:
raise OSError(errno.EPERM, error_desc, link_name)
_raise_winerror(
code,
'Error creating symbolic link \"%s\"'.format(link_name))
def islink(path):
result = GetFileAttributesW(path)
if result == INVALID_FILE_ATTRIBUTES:
return False
return bool(result & FILE_ATTRIBUTE_REPARSE_POINT)
def readlink(path):
reparse_point_handle = CreateFileW(path,
0,
0,
None,
OPEN_EXISTING,
FILE_FLAG_OPEN_REPARSE_POINT |
FILE_FLAG_BACKUP_SEMANTICS,
None)
if reparse_point_handle == INVALID_HANDLE_VALUE:
_raise_winerror(
get_last_error(),
'Error opening symbolic link \"%s\"'.format(path))
target_buffer = c_buffer(MAXIMUM_REPARSE_DATA_BUFFER_SIZE)
n_bytes_returned = DWORD()
io_result = DeviceIoControl(reparse_point_handle,
FSCTL_GET_REPARSE_POINT,
None,
0,
target_buffer,
len(target_buffer),
byref(n_bytes_returned),
None)
CloseHandle(reparse_point_handle)
if not io_result:
_raise_winerror(
get_last_error(),
'Error reading symbolic link \"%s\"'.format(path))
rdb = REPARSE_DATA_BUFFER.from_buffer(target_buffer)
if rdb.ReparseTag == IO_REPARSE_TAG_SYMLINK:
return _preserve_encoding(path, rdb.SymbolicLinkReparseBuffer.PrintName)
elif rdb.ReparseTag == IO_REPARSE_TAG_MOUNT_POINT:
return _preserve_encoding(path, rdb.MountPointReparseBuffer.PrintName)
# Unsupported reparse point type
_raise_winerror(
ERROR_NOT_SUPPORTED,
'Error reading symbolic link \"%s\"'.format(path))
def _preserve_encoding(source, target):
"""Ensures target is the same string type (i.e. unicode or str) as source."""
if is_python3():
return target
if isinstance(source, unicode): # noqa: F821
return unicode(target) # noqa: F821
return str(target)
def _raise_winerror(code, error_desc):
win_error_desc = FormatError(code).strip()
error_desc = "%s: %s".format(error_desc, win_error_desc)
raise WinError(code, error_desc)
|
