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##############################################################################
# Copyright (c) 2013-2017, Lawrence Livermore National Security, LLC.
# Produced at the Lawrence Livermore National Laboratory.
#
# This file is part of Spack.
# Created by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
# LLNL-CODE-647188
#
# For details, see https://github.com/spack/spack
# Please also see the NOTICE and LICENSE files for our notice and the LGPL.
#
# This program is free software; you can redistribute it and/or modify
# it under the terms of the GNU Lesser General Public License (as
# published by the Free Software Foundation) version 2.1, February 1999.
#
# This program is distributed in the hope that it will be useful, but
# WITHOUT ANY WARRANTY; without even the IMPLIED WARRANTY OF
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the terms and
# conditions of the GNU Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this program; if not, write to the Free Software
# Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
##############################################################################
"""LinkTree class for setting up trees of symbolic links."""
import os
import shutil
import filecmp
from llnl.util.filesystem import traverse_tree, mkdirp, touch
__all__ = ['LinkTree']
empty_file_name = '.spack-empty'
class LinkTree(object):
"""Class to create trees of symbolic links from a source directory.
LinkTree objects are constructed with a source root. Their
methods allow you to create and delete trees of symbolic links
back to the source tree in specific destination directories.
Trees comprise symlinks only to files; directries are never
symlinked to, to prevent the source directory from ever being
modified.
"""
def __init__(self, source_root):
if not os.path.exists(source_root):
raise IOError("No such file or directory: '%s'", source_root)
self._root = source_root
def find_conflict(self, dest_root, **kwargs):
"""Returns the first file in dest that conflicts with src"""
kwargs['follow_nonexisting'] = False
for src, dest in traverse_tree(self._root, dest_root, **kwargs):
if os.path.isdir(src):
if os.path.exists(dest) and not os.path.isdir(dest):
return dest
elif os.path.exists(dest):
return dest
return None
def merge(self, dest_root, link=os.symlink, **kwargs):
"""Link all files in src into dest, creating directories
if necessary.
If ignore_conflicts is True, do not break when the target exists but
rather return a list of files that could not be linked.
Note that files blocking directories will still cause an error.
"""
kwargs['order'] = 'pre'
ignore_conflicts = kwargs.get("ignore_conflicts", False)
existing = []
for src, dest in traverse_tree(self._root, dest_root, **kwargs):
if os.path.isdir(src):
if not os.path.exists(dest):
mkdirp(dest)
continue
if not os.path.isdir(dest):
raise ValueError("File blocks directory: %s" % dest)
# mark empty directories so they aren't removed on unmerge.
if not os.listdir(dest):
marker = os.path.join(dest, empty_file_name)
touch(marker)
else:
if os.path.exists(dest):
if ignore_conflicts:
existing.append(src)
else:
raise AssertionError("File already exists: %s" % dest)
else:
link(src, dest)
if ignore_conflicts:
return existing
def unmerge(self, dest_root, **kwargs):
"""Unlink all files in dest that exist in src.
Unlinks directories in dest if they are empty.
"""
kwargs['order'] = 'post'
for src, dest in traverse_tree(self._root, dest_root, **kwargs):
if os.path.isdir(src):
# Skip non-existing links.
if not os.path.exists(dest):
continue
if not os.path.isdir(dest):
raise ValueError("File blocks directory: %s" % dest)
# remove directory if it is empty.
if not os.listdir(dest):
shutil.rmtree(dest, ignore_errors=True)
# remove empty dir marker if present.
marker = os.path.join(dest, empty_file_name)
if os.path.exists(marker):
os.remove(marker)
elif os.path.exists(dest):
if not os.path.islink(dest):
raise ValueError("%s is not a link tree!" % dest)
# remove if dest is a hardlink/symlink to src; this will only
# be false if two packages are merged into a prefix and have a
# conflicting file
if filecmp.cmp(src, dest, shallow=True):
os.remove(dest)
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