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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 mkdirp
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):
self._root = source_root
def traverse(self, dest_root, **kwargs):
"""Traverse LinkTree root and dest 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. 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.
"""
# Yield directories before or after their contents.
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)
# Whether to descend when dirs dont' exist in dest.
follow_nonexisting = kwargs.get('follow_nonexisting', True)
for dirpath, dirnames, filenames in os.walk(self._root):
rel_path = dirpath[len(self._root):]
rel_path = rel_path.lstrip(os.path.sep)
dest_dirpath = os.path.join(dest_root, rel_path)
# Don't descend into ignored directories
if ignore(dest_dirpath):
return
# Don't descend into dirs in dest that do not exist in src.
if not follow_nonexisting:
dirnames[:] = [
d for d in dirnames
if os.path.exists(os.path.join(dest_dirpath, d))]
# preorder yields directories before children
if order == 'pre':
yield (dirpath, dest_dirpath)
for name in filenames:
src_file = os.path.join(dirpath, name)
dest_file = os.path.join(dest_dirpath, name)
# Ignore particular paths inside the install root.
src_relpath = src_file[len(self._root):]
src_relpath = src_relpath.lstrip(os.path.sep)
if ignore(src_relpath):
continue
yield (src_file, dest_file)
# postorder yields directories after children
if order == 'post':
yield (dirpath, dest_dirpath)
def find_conflict(self, dest_root, **kwargs):
"""Returns the first file in dest that also exists in src."""
kwargs['follow_nonexisting'] = False
for src, dest in self.traverse(dest_root, **kwargs):
if os.path.exists(dest) and not os.path.isdir(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 self.traverse(dest_root, **kwargs):
if os.path.isdir(src):
mkdirp(dest)
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 self.traverse(dest_root, **kwargs):
if os.path.isdir(dest):
if not os.listdir(dest):
# TODO: what if empty directories were present pre-merge?
shutil.rmtree(dest, ignore_errors=True)
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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