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##############################################################################
# Copyright (c) 2013, Lawrence Livermore National Security, LLC.
# Produced at the Lawrence Livermore National Laboratory.
#
# This file is part of Spack.
# Written by Todd Gamblin, tgamblin@llnl.gov, All rights reserved.
# LLNL-CODE-647188
#
# For details, see https://scalability-llnl.github.io/spack
# Please also see the LICENSE file 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 General Public License (as published by
# the Free Software Foundation) version 2.1 dated 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 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."""
__all__ = ['LinkTree']
import os
import shutil
from llnl.util.filesystem import *
empty_file_name = '.spack-empty'
def traverse_tree(source_root, dest_root, rel_path='', **kwargs):
"""Traverse two filesystem trees simultaneously.
Walks the LinkTree directory in pre or post order. Yields each
file in the source directory with a matching path from the dest
directory, along with whether the file is a directory.
e.g., for this tree::
root/
a/
file1
file2
b/
file3
When called on dest, this yields::
('root', 'dest')
('root/a', 'dest/a')
('root/a/file1', 'dest/a/file1')
('root/a/file2', 'dest/a/file2')
('root/b', 'dest/b')
('root/b/file3', 'dest/b/file3')
Optional args:
order=[pre|post] -- Whether to do pre- or post-order traveral.
ignore=<predicate> -- Predicate indicating which files to ignore.
follow_nonexisting -- Whether to descend into directories in
src that do not exit in dest. Default True.
follow_links -- Whether to descend into symlinks in src.
"""
follow_nonexisting = kwargs.get('follow_nonexisting', True)
follow_links = kwargs.get('follow_link', False)
# Yield in pre or post order?
order = kwargs.get('order', 'pre')
if order not in ('pre', 'post'):
raise ValueError("Order must be 'pre' or 'post'.")
# List of relative paths to ignore under the src root.
ignore = kwargs.get('ignore', lambda filename: False)
# Don't descend into ignored directories
if ignore(rel_path):
return
source_path = os.path.join(source_root, rel_path)
dest_path = os.path.join(dest_root, rel_path)
# preorder yields directories before children
if order == 'pre':
yield (source_path, dest_path)
for f in os.listdir(source_path):
source_child = os.path.join(source_path, f)
dest_child = os.path.join(dest_path, f)
rel_child = os.path.join(rel_path, f)
# Treat as a directory
if os.path.isdir(source_child) and (
follow_links or not os.path.islink(source_child)):
# When follow_nonexisting isn't set, don't descend into dirs
# in source that do not exist in dest
if follow_nonexisting or os.path.exists(dest_child):
tuples = traverse_tree(source_root, dest_root, rel_child, **kwargs)
for t in tuples: yield t
# Treat as a file.
elif not ignore(os.path.join(rel_path, f)):
yield (source_child, dest_child)
if order == 'post':
yield (source_path, dest_path)
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, **kwargs):
"""Link all files in src into dest, creating directories if necessary."""
kwargs['order'] = 'pre'
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:
assert(not os.path.exists(dest))
os.symlink(src, dest)
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):
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)
os.remove(dest)
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