Implement islink, readlink and realpath using Win32 api
Change-Id: I18452cbb32d24db73601ad10485dbe6bb278731c
diff --git a/platform_utils.py b/platform_utils.py
index e0fa9dc..2ad5649 100644
--- a/platform_utils.py
+++ b/platform_utils.py
@@ -242,3 +242,57 @@
raise
else:
os.rename(src, dst)
+
+
+def islink(path):
+ """Test whether a path is a symbolic link.
+
+ Availability: Windows, Unix.
+ """
+ if isWindows():
+ import platform_utils_win32
+ return platform_utils_win32.islink(path)
+ else:
+ return os.path.islink(path)
+
+
+def readlink(path):
+ """Return a string representing the path to which the symbolic link
+ points. The result may be either an absolute or relative pathname;
+ if it is relative, it may be converted to an absolute pathname using
+ os.path.join(os.path.dirname(path), result).
+
+ Availability: Windows, Unix.
+ """
+ if isWindows():
+ import platform_utils_win32
+ return platform_utils_win32.readlink(path)
+ else:
+ return os.readlink(path)
+
+
+def realpath(path):
+ """Return the canonical path of the specified filename, eliminating
+ any symbolic links encountered in the path.
+
+ Availability: Windows, Unix.
+ """
+ if isWindows():
+ current_path = os.path.abspath(path)
+ path_tail = []
+ for c in range(0, 100): # Avoid cycles
+ if islink(current_path):
+ target = readlink(current_path)
+ current_path = os.path.join(os.path.dirname(current_path), target)
+ else:
+ basename = os.path.basename(current_path)
+ if basename == '':
+ path_tail.append(current_path)
+ break
+ path_tail.append(basename)
+ current_path = os.path.dirname(current_path)
+ path_tail.reverse()
+ result = os.path.normpath(os.path.join(*path_tail))
+ return result
+ else:
+ return os.path.realpath(path)
diff --git a/platform_utils_win32.py b/platform_utils_win32.py
index 02fb013..fe76b3d 100644
--- a/platform_utils_win32.py
+++ b/platform_utils_win32.py
@@ -15,13 +15,20 @@
import errno
-from ctypes import WinDLL, get_last_error, FormatError, WinError
-from ctypes.wintypes import BOOL, LPCWSTR, DWORD
+from ctypes import WinDLL, get_last_error, FormatError, WinError, addressof
+from ctypes import c_buffer
+from ctypes.wintypes import BOOL, LPCWSTR, DWORD, HANDLE, POINTER, c_ubyte
+from ctypes.wintypes import WCHAR, USHORT, LPVOID, Structure, Union, ULONG
+from ctypes.wintypes import byref
kernel32 = WinDLL('kernel32', use_last_error=True)
+LPDWORD = POINTER(DWORD)
+UCHAR = c_ubyte
+
# Win32 error codes
ERROR_SUCCESS = 0
+ERROR_NOT_SUPPORTED = 50
ERROR_PRIVILEGE_NOT_HELD = 1314
# Win32 API entry points
@@ -35,6 +42,94 @@
SYMBOLIC_LINK_FLAG_FILE = 0x00
SYMBOLIC_LINK_FLAG_DIRECTORY = 0x01
+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."""
@@ -58,6 +153,65 @@
error_desc = FormatError(code).strip()
if code == ERROR_PRIVILEGE_NOT_HELD:
raise OSError(errno.EPERM, error_desc, link_name)
- error_desc = 'Error creating symbolic link %s: %s'.format(
- link_name, error_desc)
- raise WinError(code, error_desc)
+ _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 symblic 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 symblic 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 symblic link \"%s\"'.format(path))
+
+
+def _preserve_encoding(source, target):
+ """Ensures target is the same string type (i.e. unicode or str) as source."""
+ if isinstance(source, unicode):
+ return unicode(target)
+ 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)
diff --git a/project.py b/project.py
index d4c5afd..655b202 100644
--- a/project.py
+++ b/project.py
@@ -103,7 +103,7 @@
"""
global _project_hook_list
if _project_hook_list is None:
- d = os.path.realpath(os.path.abspath(os.path.dirname(__file__)))
+ d = platform_utils.realpath(os.path.abspath(os.path.dirname(__file__)))
d = os.path.join(d, 'hooks')
_project_hook_list = [os.path.join(d, x) for x in os.listdir(d)]
return _project_hook_list
@@ -275,7 +275,7 @@
def __linkIt(self, relSrc, absDest):
# link file if it does not exist or is out of date
- if not os.path.islink(absDest) or (os.readlink(absDest) != relSrc):
+ if not platform_utils.islink(absDest) or (platform_utils.readlink(absDest) != relSrc):
try:
# remove existing file first, since it might be read-only
if os.path.lexists(absDest):
@@ -2315,10 +2315,10 @@
print("Retrying clone after deleting %s" %
self.gitdir, file=sys.stderr)
try:
- platform_utils.rmtree(os.path.realpath(self.gitdir))
- if self.worktree and os.path.exists(os.path.realpath
+ platform_utils.rmtree(platform_utils.realpath(self.gitdir))
+ if self.worktree and os.path.exists(platform_utils.realpath
(self.worktree)):
- platform_utils.rmtree(os.path.realpath(self.worktree))
+ platform_utils.rmtree(platform_utils.realpath(self.worktree))
return self._InitGitDir(mirror_git=mirror_git, force_sync=False)
except:
raise e
@@ -2370,7 +2370,7 @@
self._InitHooks()
def _InitHooks(self):
- hooks = os.path.realpath(self._gitdir_path('hooks'))
+ hooks = platform_utils.realpath(self._gitdir_path('hooks'))
if not os.path.exists(hooks):
os.makedirs(hooks)
for stock_hook in _ProjectHooks():
@@ -2386,7 +2386,7 @@
continue
dst = os.path.join(hooks, name)
- if os.path.islink(dst):
+ if platform_utils.islink(dst):
continue
if os.path.exists(dst):
if filecmp.cmp(stock_hook, dst, shallow=False):
@@ -2448,9 +2448,9 @@
symlink_dirs += self.working_tree_dirs
to_symlink = symlink_files + symlink_dirs
for name in set(to_symlink):
- dst = os.path.realpath(os.path.join(destdir, name))
+ dst = platform_utils.realpath(os.path.join(destdir, name))
if os.path.lexists(dst):
- src = os.path.realpath(os.path.join(srcdir, name))
+ src = platform_utils.realpath(os.path.join(srcdir, name))
# Fail if the links are pointing to the wrong place
if src != dst:
_error('%s is different in %s vs %s', name, destdir, srcdir)
@@ -2482,10 +2482,10 @@
if copy_all:
to_copy = os.listdir(gitdir)
- dotgit = os.path.realpath(dotgit)
+ dotgit = platform_utils.realpath(dotgit)
for name in set(to_copy).union(to_symlink):
try:
- src = os.path.realpath(os.path.join(gitdir, name))
+ src = platform_utils.realpath(os.path.join(gitdir, name))
dst = os.path.join(dotgit, name)
if os.path.lexists(dst):
@@ -2498,7 +2498,7 @@
if name in to_symlink:
platform_utils.symlink(
os.path.relpath(src, os.path.dirname(dst)), dst)
- elif copy_all and not os.path.islink(dst):
+ elif copy_all and not platform_utils.islink(dst):
if os.path.isdir(src):
shutil.copytree(src, dst)
elif os.path.isfile(src):
@@ -2556,7 +2556,7 @@
raise
def _gitdir_path(self, path):
- return os.path.realpath(os.path.join(self.gitdir, path))
+ return platform_utils.realpath(os.path.join(self.gitdir, path))
def _revlist(self, *args, **kw):
a = []
diff --git a/subcmds/sync.py b/subcmds/sync.py
index b88c596..93fea23 100644
--- a/subcmds/sync.py
+++ b/subcmds/sync.py
@@ -498,7 +498,7 @@
dirs_to_remove += [os.path.join(root, d) for d in dirs
if os.path.join(root, d) not in dirs_to_remove]
for d in reversed(dirs_to_remove):
- if os.path.islink(d):
+ if platform_utils.islink(d):
try:
os.remove(d)
except OSError:
