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
| from win32file import *
from winioctlcon import FSCTL_GET_REPARSE_POINT
__all__ = ['islink', 'readlink']
# Win32file doesn't seem to have this attribute.
FILE_ATTRIBUTE_REPARSE_POINT = 1024
# To make things easier.
REPARSE_FOLDER = (FILE_ATTRIBUTE_DIRECTORY | FILE_ATTRIBUTE_REPARSE_POINT)
# For the parse_reparse_buffer function
SYMBOLIC_LINK = 'symbolic'
MOUNTPOINT = 'mountpoint'
GENERIC = 'generic'
def islink(fpath):
""" Windows islink implementation. """
if GetFileAttributes(fpath) & REPARSE_FOLDER == REPARSE_FOLDER:
return True
return False
def parse_reparse_buffer(original, reparse_type=SYMBOLIC_LINK):
""" Implementing the below in Python:
typedef struct _REPARSE_DATA_BUFFER {
ULONG ReparseTag;
USHORT ReparseDataLength;
USHORT Reserved;
union {
struct {
USHORT SubstituteNameOffset;
USHORT SubstituteNameLength;
USHORT PrintNameOffset;
USHORT PrintNameLength;
ULONG Flags;
WCHAR PathBuffer[1];
} SymbolicLinkReparseBuffer;
struct {
USHORT SubstituteNameOffset;
USHORT SubstituteNameLength;
USHORT PrintNameOffset;
USHORT PrintNameLength;
WCHAR PathBuffer[1];
} MountPointReparseBuffer;
struct {
UCHAR DataBuffer[1];
} GenericReparseBuffer;
} DUMMYUNIONNAME;
} REPARSE_DATA_BUFFER, *PREPARSE_DATA_BUFFER;
"""
# Size of our data types
SZULONG = 4 # sizeof(ULONG)
SZUSHORT = 2 # sizeof(USHORT)
# Our structure.
# Probably a better way to iterate a dictionary in a particular order,
# but I was in a hurry, unfortunately, so I used pkeys.
buffer = {
'tag' : SZULONG,
'data_length' : SZUSHORT,
'reserved' : SZUSHORT,
SYMBOLIC_LINK : {
'substitute_name_offset' : SZUSHORT,
'substitute_name_length' : SZUSHORT,
'print_name_offset' : SZUSHORT,
'print_name_length' : SZUSHORT,
'flags' : SZULONG,
'buffer' : u'',
'pkeys' : [
'substitute_name_offset',
'substitute_name_length',
'print_name_offset',
'print_name_length',
'flags',
]
},
MOUNTPOINT : {
'substitute_name_offset' : SZUSHORT,
'substitute_name_length' : SZUSHORT,
'print_name_offset' : SZUSHORT,
'print_name_length' : SZUSHORT,
'buffer' : u'',
'pkeys' : [
'substitute_name_offset',
'substitute_name_length',
'print_name_offset',
'print_name_length',
]
},
GENERIC : {
'pkeys' : [],
'buffer': ''
}
}
# Header stuff
buffer['tag'] = original[:SZULONG]
buffer['data_length'] = original[SZULONG:SZUSHORT]
buffer['reserved'] = original[SZULONG+SZUSHORT:SZUSHORT]
original = original[8:]
# Parsing
k = reparse_type
for c in buffer[k]['pkeys']:
if type(buffer[k][c]) == int:
sz = buffer[k][c]
bytes = original[:sz]
buffer[k][c] = 0
for b in bytes:
n = ord(b)
if n:
buffer[k][c] += n
original = original[sz:]
# Using the offset and length's grabbed, we'll set the buffer.
buffer[k]['buffer'] = original
return buffer
def readlink(fpath):
""" Windows readlink implementation. """
# This wouldn't return true if the file didn't exist, as far as I know.
if not islink(fpath):
return None
# Open the file correctly depending on the string type.
handle = CreateFileW(fpath, GENERIC_READ, 0, None, OPEN_EXISTING, FILE_FLAG_OPEN_REPARSE_POINT, 0) \
if type(fpath) == unicode else \
CreateFile(fpath, GENERIC_READ, 0, None, OPEN_EXISTING, FILE_FLAG_OPEN_REPARSE_POINT, 0)
# MAXIMUM_REPARSE_DATA_BUFFER_SIZE = 16384 = (16*1024)
buffer = DeviceIoControl(handle, FSCTL_GET_REPARSE_POINT, None, 16*1024)
# Above will return an ugly string (byte array), so we'll need to parse it.
# But first, we'll close the handle to our file so we're not locking it anymore.
CloseHandle(handle)
# Minimum possible length (assuming that the length of the target is bigger than 0)
if len(buffer) < 9:
return None
# Parse and return our result.
result = parse_reparse_buffer(buffer)
offset = result[SYMBOLIC_LINK]['substitute_name_offset']
ending = offset + result[SYMBOLIC_LINK]['substitute_name_length']
rpath = result[SYMBOLIC_LINK]['buffer'][offset:ending].replace('\x00','')
if len(rpath) > 4 and rpath[0:4] == '\\??\\':
rpath = rpath[4:]
return rpath
def realpath(fpath):
from os import path
while islink(fpath):
rpath = readlink(fpath)
if not path.isabs(rpath):
rpath = path.abspath(path.join(path.dirname(fpath), rpath))
fpath = rpath
return fpath
def example():
from os import system, unlink
system('cmd.exe /c echo Hello World > test.txt')
system('mklink test-link.txt test.txt')
print 'IsLink: %s' % islink('test-link.txt')
print 'ReadLink: %s' % readlink('test-link.txt')
print 'RealPath: %s' % realpath('test-link.txt')
unlink('test-link.txt')
unlink('test.txt')
if __name__=='__main__':
example() |
Partager