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# Copyright 2013 The Chromium Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.
from copy import deepcopy
from file_system import FileSystem, StatInfo, FileNotFoundError
from future import Future
def _GetAsyncFetchCallback(unpatched_files_future,
patched_files_future,
dirs_value,
patched_file_system):
def patch_directory_listing(path, original_listing):
added, deleted, modified = (
patched_file_system._GetDirectoryListingFromPatch(path))
if original_listing is None:
if len(added) == 0:
raise FileNotFoundError('Directory %s not found in the patch.' % path)
return added
return list((set(original_listing) | set(added)) - set(deleted))
def resolve():
files = unpatched_files_future.Get()
files.update(patched_files_future.Get())
files.update(
dict((path, patch_directory_listing(path, dirs_value[path]))
for path in dirs_value))
return files
return resolve
class PatchedFileSystem(FileSystem):
''' Class to fetch resources with a patch applied.
'''
def __init__(self, base_file_system, patcher):
self._base_file_system = base_file_system
self._patcher = patcher
def Read(self, paths, skip_not_found=False):
patched_files = set()
added, deleted, modified = self._patcher.GetPatchedFiles()
if set(paths) & set(deleted):
def raise_file_not_found():
raise FileNotFoundError('Files are removed from the patch.')
return Future(callback=raise_file_not_found)
patched_files |= (set(added) | set(modified))
dir_paths = set(path for path in paths if path.endswith('/'))
file_paths = set(paths) - dir_paths
patched_paths = file_paths & patched_files
unpatched_paths = file_paths - patched_files
return Future(callback=_GetAsyncFetchCallback(
self._base_file_system.Read(unpatched_paths,
skip_not_found=skip_not_found),
self._patcher.Apply(patched_paths, self._base_file_system),
self._TryReadDirectory(dir_paths),
self))
def Refresh(self):
return self._base_file_system.Refresh()
''' Given the list of patched files, it's not possible to determine whether
a directory to read exists in self._base_file_system. So try reading each one
and handle FileNotFoundError.
'''
def _TryReadDirectory(self, paths):
value = {}
for path in paths:
assert path.endswith('/')
try:
value[path] = self._base_file_system.ReadSingle(path).Get()
except FileNotFoundError:
value[path] = None
return value
def _GetDirectoryListingFromPatch(self, path):
assert path.endswith('/')
def _FindChildrenInPath(files, path):
result = []
for f in files:
if f.startswith(path):
child_path = f[len(path):]
if '/' in child_path:
child_name = child_path[0:child_path.find('/') + 1]
else:
child_name = child_path
result.append(child_name)
return result
added, deleted, modified = (tuple(
_FindChildrenInPath(files, path)
for files in self._patcher.GetPatchedFiles()))
# A patch applies to files only. It cannot delete directories.
deleted_files = [child for child in deleted if not child.endswith('/')]
# However, these directories are actually modified because their children
# are patched.
modified += [child for child in deleted if child.endswith('/')]
return (added, deleted_files, modified)
def _PatchStat(self, stat_info, version, added, deleted, modified):
assert len(added) + len(deleted) + len(modified) > 0
assert stat_info.child_versions is not None
# Deep copy before patching to make sure it doesn't interfere with values
# cached in memory.
stat_info = deepcopy(stat_info)
stat_info.version = version
for child in added + modified:
stat_info.child_versions[child] = version
for child in deleted:
if stat_info.child_versions.get(child):
del stat_info.child_versions[child]
return stat_info
def Stat(self, path):
version = self._patcher.GetVersion()
assert version is not None
version = 'patched_%s' % version
directory, filename = path.rsplit('/', 1)
added, deleted, modified = self._GetDirectoryListingFromPatch(
directory + '/')
if len(added) > 0:
# There are new files added. It's possible (if |directory| is new) that
# self._base_file_system.Stat will throw an exception.
try:
stat_info = self._PatchStat(
self._base_file_system.Stat(directory + '/'),
version,
added,
deleted,
modified)
except FileNotFoundError:
stat_info = StatInfo(
version,
dict((child, version) for child in added + modified))
elif len(deleted) + len(modified) > 0:
# No files were added.
stat_info = self._PatchStat(self._base_file_system.Stat(directory + '/'),
version,
added,
deleted,
modified)
else:
# No changes are made in this directory.
return self._base_file_system.Stat(path)
if stat_info.child_versions is not None:
if filename:
if filename in stat_info.child_versions:
stat_info = StatInfo(stat_info.child_versions[filename])
else:
raise FileNotFoundError('%s was not in child versions' % filename)
return stat_info
def GetIdentity(self):
return '%s(%s,%s)' % (self.__class__.__name__,
self._base_file_system.GetIdentity(),
self._patcher.GetIdentity())
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