blob: 540c97ef5655226cb4b90f276debb39732da422c [file] [log] [blame]
# Copyright 2009 The Native Client Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
"""Hard link support for Windows.
This module is a SCons tool which should be include in the topmost windows
environment. It is usually included by the target_platform_windows tool.
from __future__ import print_function
import os
import stat
import sys
import SCons
if sys.platform == 'win32':
# Only attempt to load pywin32 on Windows systems
import win32file
except ImportError:
print('Warning: Unable to load win32file module; using copy instead of'
' hard linking for env.Install(). Is pywin32 present?')
# Python 2.4 and 2.5's os module doesn't support on Windows, even
# though Windows does have hard-link capability on NTFS filesystems. So by
# default, SCons will insist on copying files instead of linking them as it
# does on other (linux,mac) OS's.
# Use the CreateHardLink() functionality from pywin32 to provide hard link
# capability on Windows also.
def _HardLink(fs, src, dst):
"""Hard link function for hooking into SCons.Node.FS.
fs: Filesystem class to use.
src: Source filename to link to.
dst: Destination link name to create.
OSError: The link could not be created.
# A hard link shares file permissions from the source. On Windows, the write
# access of the file itself determines whether the file can be deleted
# (unlike Linux/Mac, where it's the write access of the containing
# directory). So if we made a link from a read-only file, the only way to
# delete it would be to make the link writable, which would have the
# unintended effect of making the source writable too.
# So if the source is read-only, we can't hard link from it.
if not stat.S_IMODE(fs.stat(src)[stat.ST_MODE]) & stat.S_IWRITE:
raise OSError('Unsafe to hard-link read-only file: %s' % src)
# If the file is writable, only hard-link from it if it was build by SCons.
# Those files shouldn't later become read-only. We don't hard-link from
# writable files which SCons didn't create, because those could become
# read-only (for example, following a 'p4 submit'), which as indicated above
# would make our link read-only too.
if not fs.File(src).has_builder():
raise OSError('Unsafe to hard-link file not built by SCons: %s' % src)
win32file.CreateHardLink(dst, src)
except win32file.error, msg:
# Translate errors into standard OSError which SCons expects.
raise OSError(msg)
def generate(env):
# NOTE: SCons requires the use of this name, which fails gpylint.
"""SCons entry point for this tool."""
env = env # Silence gpylint
# Patch in our hard link function, if we were able to load pywin32
if 'win32file' in globals():
SCons.Node.FS._hardlink_func = _HardLink