# Copyright 2013-2023 Lawrence Livermore National Security, LLC and other
# Spack Project Developers. See the top-level COPYRIGHT file for details.
#
# SPDX-License-Identifier: (Apache-2.0 OR MIT)
import errno
import os
import shutil
import sys
import tempfile
from os.path import exists, join
from llnl.util import lang
if sys.platform == "win32":
from win32file import CreateHardLink
[docs]def symlink(real_path, link_path):
"""
Create a symbolic link.
On Windows, use junctions if os.symlink fails.
"""
if sys.platform != "win32":
os.symlink(real_path, link_path)
elif _win32_can_symlink():
# Windows requires target_is_directory=True when the target is a dir.
os.symlink(real_path, link_path, target_is_directory=os.path.isdir(real_path))
else:
try:
# Try to use junctions
_win32_junction(real_path, link_path)
except OSError as e:
if e.errno == errno.EEXIST:
# EEXIST error indicates that file we're trying to "link"
# is already present, don't bother trying to copy which will also fail
# just raise
raise
else:
# If all else fails, fall back to copying files
shutil.copyfile(real_path, link_path)
[docs]def islink(path):
return os.path.islink(path) or _win32_is_junction(path)
# '_win32' functions based on
# https://github.com/Erotemic/ubelt/blob/master/ubelt/util_links.py
def _win32_junction(path, link):
# junctions require absolute paths
if not os.path.isabs(link):
link = os.path.abspath(link)
# os.symlink will fail if link exists, emulate the behavior here
if exists(link):
raise OSError(errno.EEXIST, "File exists: %s -> %s" % (link, path))
if not os.path.isabs(path):
parent = os.path.join(link, os.pardir)
path = os.path.join(parent, path)
path = os.path.abspath(path)
CreateHardLink(link, path)
@lang.memoized
def _win32_can_symlink():
tempdir = tempfile.mkdtemp()
dpath = join(tempdir, "dpath")
fpath = join(tempdir, "fpath.txt")
dlink = join(tempdir, "dlink")
flink = join(tempdir, "flink.txt")
import llnl.util.filesystem as fs
fs.touchp(fpath)
try:
os.symlink(dpath, dlink)
can_symlink_directories = os.path.islink(dlink)
except OSError:
can_symlink_directories = False
try:
os.symlink(fpath, flink)
can_symlink_files = os.path.islink(flink)
except OSError:
can_symlink_files = False
# Cleanup the test directory
shutil.rmtree(tempdir)
return can_symlink_directories and can_symlink_files
def _win32_is_junction(path):
"""
Determines if a path is a win32 junction
"""
if os.path.islink(path):
return False
if sys.platform == "win32":
import ctypes.wintypes
GetFileAttributes = ctypes.windll.kernel32.GetFileAttributesW
GetFileAttributes.argtypes = (ctypes.wintypes.LPWSTR,)
GetFileAttributes.restype = ctypes.wintypes.DWORD
INVALID_FILE_ATTRIBUTES = 0xFFFFFFFF
FILE_ATTRIBUTE_REPARSE_POINT = 0x400
res = GetFileAttributes(path)
return res != INVALID_FILE_ATTRIBUTES and bool(res & FILE_ATTRIBUTE_REPARSE_POINT)
return False