nzbToMedia/libs/win/path/py37compat.py
2022-11-29 00:44:47 -05:00

126 lines
4.6 KiB
Python

import functools
import os
def best_realpath(module):
"""
Given a path module (i.e. ntpath, posixpath),
determine the best 'realpath' function to use
for best future compatibility.
"""
needs_backport = module.realpath is module.abspath
return realpath_backport if needs_backport else module.realpath
# backport taken from jaraco.windows 5
def realpath_backport(path):
if isinstance(path, str):
prefix = '\\\\?\\'
unc_prefix = prefix + 'UNC'
new_unc_prefix = '\\'
cwd = os.getcwd()
else:
prefix = b'\\\\?\\'
unc_prefix = prefix + b'UNC'
new_unc_prefix = b'\\'
cwd = os.getcwdb()
had_prefix = path.startswith(prefix)
path, ok = _resolve_path(cwd, path, {})
# The path returned by _getfinalpathname will always start with \\?\ -
# strip off that prefix unless it was already provided on the original
# path.
if not had_prefix:
# For UNC paths, the prefix will actually be \\?\UNC - handle that
# case as well.
if path.startswith(unc_prefix):
path = new_unc_prefix + path[len(unc_prefix) :]
elif path.startswith(prefix):
path = path[len(prefix) :]
return path
def _resolve_path(path, rest, seen): # noqa: C901
# Windows normalizes the path before resolving symlinks; be sure to
# follow the same behavior.
rest = os.path.normpath(rest)
if isinstance(rest, str):
sep = '\\'
else:
sep = b'\\'
if os.path.isabs(rest):
drive, rest = os.path.splitdrive(rest)
path = drive + sep
rest = rest[1:]
while rest:
name, _, rest = rest.partition(sep)
new_path = os.path.join(path, name) if path else name
if os.path.exists(new_path):
if not rest:
# The whole path exists. Resolve it using the OS.
path = os.path._getfinalpathname(new_path)
else:
# The OS can resolve `new_path`; keep traversing the path.
path = new_path
elif not os.path.lexists(new_path):
# `new_path` does not exist on the filesystem at all. Use the
# OS to resolve `path`, if it exists, and then append the
# remainder.
if os.path.exists(path):
path = os.path._getfinalpathname(path)
rest = os.path.join(name, rest) if rest else name
return os.path.join(path, rest), True
else:
# We have a symbolic link that the OS cannot resolve. Try to
# resolve it ourselves.
# On Windows, symbolic link resolution can be partially or
# fully disabled [1]. The end result of a disabled symlink
# appears the same as a broken symlink (lexists() returns True
# but exists() returns False). And in both cases, the link can
# still be read using readlink(). Call stat() and check the
# resulting error code to ensure we don't circumvent the
# Windows symbolic link restrictions.
# [1] https://technet.microsoft.com/en-us/library/cc754077.aspx
try:
os.stat(new_path)
except OSError as e:
# WinError 1463: The symbolic link cannot be followed
# because its type is disabled.
if e.winerror == 1463:
raise
key = os.path.normcase(new_path)
if key in seen:
# This link has already been seen; try to use the
# previously resolved value.
path = seen[key]
if path is None:
# It has not yet been resolved, which means we must
# have a symbolic link loop. Return what we have
# resolved so far plus the remainder of the path (who
# cares about the Zen of Python?).
path = os.path.join(new_path, rest) if rest else new_path
return path, False
else:
# Mark this link as in the process of being resolved.
seen[key] = None
# Try to resolve it.
path, ok = _resolve_path(path, os.readlink(new_path), seen)
if ok:
# Resolution succeded; store the resolved value.
seen[key] = path
else:
# Resolution failed; punt.
return (os.path.join(path, rest) if rest else path), False
return path, True
def lru_cache(user_function):
"""
Support for lru_cache(user_function)
"""
return functools.lru_cache()(user_function)