Create NTFS junction point in Python
I answered this in a similar question, so I'll copy my answer to that below. Since writing that answer, I ended up writing a python-only (if you can call a module that uses ctypes python-only) module to creating, reading, and checking junctions which can be found in this folder. Hope that helps.
Also, unlike the answer that utilizes uses the CreateSymbolicLinkA API, the linked implementation should work on any Windows version that supports junctions. CreateSymbolicLinkA is only supported in Vista+.
Answer:
Or if you want to use pywin32, you can use the previously stated method, and to read, use:
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 functionSYMBOLIC_LINK = 'symbolic'MOUNTPOINT = 'mountpoint'GENERIC = 'generic'def islink(fpath): """ Windows islink implementation. """ if GetFileAttributes(fpath) & REPARSE_FOLDER: return True return Falsedef 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 bufferdef 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 rpathdef 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 fpathdef 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()Adjust the attributes in the CreateFile to your needs, but for a normal situation, it should work. Feel free to improve on it.
It should also work for folder junctions if you use MOUNTPOINT instead of SYMBOLIC_LINK.
You may way to check that
sys.getwindowsversion()[0] >= 6if you put this into something you're releasing, since this form of symbolic link is only supported on Vista+.
you can use python win32 API modules e.g.
import win32filewin32file.CreateSymbolicLink(srcDir, targetDir, 1)see http://docs.activestate.com/activepython/2.5/pywin32/win32file__CreateSymbolicLink_meth.html for more details
if you do not want to rely on that too, you can always use ctypes and directly call CreateSymbolicLinl win32 API, which is anyway a simple call
here is example call using ctypes
import ctypeskdll = ctypes.windll.LoadLibrary("kernel32.dll")kdll.CreateSymbolicLinkA("d:\testdir", "d:\testdir_link", 1)MSDN says Minimum supported client Windows Vista