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# 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
import os
import platform
import shutil
import stat
def isWindows():
"""Returns True when running with the native port of Python for Windows,
False when running on any other platform (including the Cygwin port of
Python).
"""
# Note: The cygwin port of Python returns "CYGWIN_NT_xxx"
return platform.system() == "Windows"
def symlink(source, link_name):
"""Creates a symbolic link pointing to source named link_name.
Note: On Windows, source must exist on disk, as the implementation needs
to know whether to create a "File" or a "Directory" symbolic link.
"""
if isWindows():
import platform_utils_win32
source = _validate_winpath(source)
link_name = _validate_winpath(link_name)
target = os.path.join(os.path.dirname(link_name), source)
if isdir(target):
platform_utils_win32.create_dirsymlink(
_makelongpath(source), link_name
)
else:
platform_utils_win32.create_filesymlink(
_makelongpath(source), link_name
)
else:
return os.symlink(source, link_name)
def _validate_winpath(path):
path = os.path.normpath(path)
if _winpath_is_valid(path):
return path
raise ValueError(
f'Path "{path}" must be a relative path or an absolute '
"path starting with a drive letter"
)
def _winpath_is_valid(path):
"""Windows only: returns True if path is relative (e.g. ".\\foo") or is
absolute including a drive letter (e.g. "c:\\foo"). Returns False if path
is ambiguous (e.g. "x:foo" or "\\foo").
"""
assert isWindows()
path = os.path.normpath(path)
drive, tail = os.path.splitdrive(path)
if tail:
if not drive:
return tail[0] != os.sep # "\\foo" is invalid
else:
return tail[0] == os.sep # "x:foo" is invalid
else:
return not drive # "x:" is invalid
def _makelongpath(path):
"""Return the input path normalized to support the Windows long path syntax
("\\\\?\\" prefix) if needed, i.e. if the input path is longer than the
MAX_PATH limit.
"""
if isWindows():
# Note: MAX_PATH is 260, but, for directories, the maximum value is
# actually 246.
if len(path) < 246:
return path
if path.startswith("\\\\?\\"):
return path
if not os.path.isabs(path):
return path
# Append prefix and ensure unicode so that the special longpath syntax
# is supported by underlying Win32 API calls
return "\\\\?\\" + os.path.normpath(path)
else:
return path
def rmtree(path, ignore_errors=False):
"""shutil.rmtree(path) wrapper with support for long paths on Windows.
Availability: Unix, Windows.
"""
onerror = None
if isWindows():
path = _makelongpath(path)
onerror = handle_rmtree_error
shutil.rmtree(path, ignore_errors=ignore_errors, onerror=onerror)
def handle_rmtree_error(function, path, excinfo):
# Allow deleting read-only files.
os.chmod(path, stat.S_IWRITE)
function(path)
def rename(src, dst):
"""os.rename(src, dst) wrapper with support for long paths on Windows.
Availability: Unix, Windows.
"""
if isWindows():
# On Windows, rename fails if destination exists, see
# https://docs.python.org/2/library/os.html#os.rename
try:
os.rename(_makelongpath(src), _makelongpath(dst))
except OSError as e:
if e.errno == errno.EEXIST:
os.remove(_makelongpath(dst))
os.rename(_makelongpath(src), _makelongpath(dst))
else:
raise
else:
shutil.move(src, dst)
def remove(path, missing_ok=False):
"""Remove (delete) the file path. This is a replacement for os.remove that
allows deleting read-only files on Windows, with support for long paths and
for deleting directory symbolic links.
Availability: Unix, Windows.
"""
longpath = _makelongpath(path) if isWindows() else path
try:
os.remove(longpath)
except OSError as e:
if e.errno == errno.EACCES:
os.chmod(longpath, stat.S_IWRITE)
# Directory symbolic links must be deleted with 'rmdir'.
if islink(longpath) and isdir(longpath):
os.rmdir(longpath)
else:
os.remove(longpath)
elif missing_ok and e.errno == errno.ENOENT:
pass
else:
raise
def walk(top, topdown=True, onerror=None, followlinks=False):
"""os.walk(path) wrapper with support for long paths on Windows.
Availability: Windows, Unix.
"""
if isWindows():
return _walk_windows_impl(top, topdown, onerror, followlinks)
else:
return os.walk(top, topdown, onerror, followlinks)
def _walk_windows_impl(top, topdown, onerror, followlinks):
try:
names = listdir(top)
except Exception as err:
if onerror is not None:
onerror(err)
return
dirs, nondirs = [], []
for name in names:
if isdir(os.path.join(top, name)):
dirs.append(name)
else:
nondirs.append(name)
if topdown:
yield top, dirs, nondirs
for name in dirs:
new_path = os.path.join(top, name)
if followlinks or not islink(new_path):
yield from _walk_windows_impl(
new_path, topdown, onerror, followlinks
)
if not topdown:
yield top, dirs, nondirs
def listdir(path):
"""os.listdir(path) wrapper with support for long paths on Windows.
Availability: Windows, Unix.
"""
return os.listdir(_makelongpath(path))
def rmdir(path):
"""os.rmdir(path) wrapper with support for long paths on Windows.
Availability: Windows, Unix.
"""
os.rmdir(_makelongpath(path))
def isdir(path):
"""os.path.isdir(path) wrapper with support for long paths on Windows.
Availability: Windows, Unix.
"""
return os.path.isdir(_makelongpath(path))
def islink(path):
"""os.path.islink(path) wrapper with support for long paths on Windows.
Availability: Windows, Unix.
"""
if isWindows():
import platform_utils_win32
return platform_utils_win32.islink(_makelongpath(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(_makelongpath(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)