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#!/usr/bin/env python3
#
# Copyright (C) 2018 Bloomberg Finance LP
#
# 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; either
# version 2 of the License, or (at your option) any later version.
#
# This library 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 GNU
# Lesser General Public License for more details.
#
# You should have received a copy of the GNU Lesser General Public
# License along with this library. If not, see <http://www.gnu.org/licenses/>.
#
# Authors:
# Jim MacArthur <jim.macarthur@codethink.co.uk>
"""
FileBasedDirectory
=========
Implementation of the Directory class which backs onto a normal POSIX filing system.
See also: :ref:`sandboxing`.
"""
import os
import time
from .directory import Directory, VirtualDirectoryError
from ..utils import link_files, copy_files, list_relative_paths, _get_link_mtime, _magic_timestamp
from ..utils import _set_deterministic_user, _set_deterministic_mtime
# FileBasedDirectory intentionally doesn't call its superclass constuctor,
# which is meant to be unimplemented.
# pylint: disable=super-init-not-called
class _FileObject():
"""A description of a file in a virtual directory. The contents of
this class are never used, but there needs to be something present
for files so is_empty() works correctly.
"""
def __init__(self, virtual_directory: Directory, filename: str):
self.directory = virtual_directory
self.filename = filename
class FileBasedDirectory(Directory):
def __init__(self, external_directory=None):
self.external_directory = external_directory
self.index = {}
self._directory_read = False
def _populate_index(self):
if self._directory_read:
return
for entry in os.listdir(self.external_directory):
if os.path.isdir(os.path.join(self.external_directory, entry)):
self.index[entry] = FileBasedDirectory(os.path.join(self.external_directory, entry))
else:
self.index[entry] = _FileObject(self, entry)
self._directory_read = True
def descend(self, subdirectory_spec, create=False):
""" See superclass Directory for arguments """
# It's very common to send a directory name instead of a list and this causes
# bizarre errors, so check for it here
if not isinstance(subdirectory_spec, list):
subdirectory_spec = [subdirectory_spec]
# Because of the way split works, it's common to get a list which begins with
# an empty string. Detect these and remove them.
while subdirectory_spec and subdirectory_spec[0] == "":
subdirectory_spec.pop(0)
if not subdirectory_spec:
return self
self._populate_index()
if subdirectory_spec[0] in self.index:
entry = self.index[subdirectory_spec[0]]
if isinstance(entry, FileBasedDirectory):
new_path = os.path.join(self.external_directory, subdirectory_spec[0])
return FileBasedDirectory(new_path).descend(subdirectory_spec[1:], create)
else:
error = "Cannot descend into {}, which is a '{}' in the directory {}"
raise VirtualDirectoryError(error.format(subdirectory_spec[0],
type(entry).__name__,
self.external_directory))
else:
if create:
new_path = os.path.join(self.external_directory, subdirectory_spec[0])
os.makedirs(new_path, exist_ok=True)
self.index[subdirectory_spec[0]] = FileBasedDirectory(new_path).descend(subdirectory_spec[1:], create)
return self.index[subdirectory_spec[0]]
else:
error = "No entry called '{}' found in the directory rooted at {}"
raise VirtualDirectoryError(error.format(subdirectory_spec[0], self.external_directory))
def import_files(self, external_pathspec, *, files=None,
report_written=True, update_utimes=False,
can_link=False):
""" See superclass Directory for arguments """
if isinstance(external_pathspec, Directory):
source_directory = external_pathspec.external_directory
else:
source_directory = external_pathspec
if can_link and not update_utimes:
import_result = link_files(source_directory, self.external_directory, files=files,
ignore_missing=False, report_written=report_written)
else:
import_result = copy_files(source_directory, self.external_directory, files=files,
ignore_missing=False, report_written=report_written)
if update_utimes:
cur_time = time.time()
for f in import_result.files_written:
os.utime(os.path.join(self.external_directory, f), times=(cur_time, cur_time))
self._mark_changed()
return import_result
def _mark_changed(self):
self._directory_read = False
def set_deterministic_mtime(self):
_set_deterministic_mtime(self.external_directory)
def set_deterministic_user(self):
_set_deterministic_user(self.external_directory)
def export_files(self, to_directory, *, can_link=False, can_destroy=False):
if can_destroy:
# Try a simple rename of the sandbox root; if that
# doesnt cut it, then do the regular link files code path
try:
os.rename(self.external_directory, to_directory)
return
except OSError:
# Proceed using normal link/copy
pass
os.makedirs(to_directory, exist_ok=True)
if can_link:
link_files(self.external_directory, to_directory)
else:
copy_files(self.external_directory, to_directory)
# Add a directory entry deterministically to a tar file
#
# This function takes extra steps to ensure the output is deterministic.
# First, it sorts the results of os.listdir() to ensure the ordering of
# the files in the archive is the same. Second, it sets a fixed
# timestamp for each entry. See also https://bugs.python.org/issue24465.
def export_to_tar(self, tf, dir_arcname, mtime=_magic_timestamp):
# We need directories here, including non-empty ones,
# so list_relative_paths is not used.
for filename in sorted(os.listdir(self.external_directory)):
source_name = os.path.join(self.external_directory, filename)
arcname = os.path.join(dir_arcname, filename)
tarinfo = tf.gettarinfo(source_name, arcname)
tarinfo.mtime = mtime
if tarinfo.isreg():
with open(source_name, "rb") as f:
tf.addfile(tarinfo, f)
elif tarinfo.isdir():
tf.addfile(tarinfo)
self.descend(filename.split(os.path.sep)).export_to_tar(tf, arcname, mtime)
else:
tf.addfile(tarinfo)
def is_empty(self):
self._populate_index()
return len(self.index) == 0
def mark_unmodified(self):
""" Marks all files in this directory (recursively) as unmodified.
"""
_set_deterministic_mtime(self.external_directory)
def list_modified_paths(self):
"""Provide a list of relative paths which have been modified since the
last call to mark_unmodified.
Return value: List(str) - list of modified paths
"""
return [f for f in list_relative_paths(self.external_directory)
if _get_link_mtime(os.path.join(self.external_directory, f)) != _magic_timestamp]
def list_relative_paths(self):
"""Provide a list of all relative paths.
Return value: List(str) - list of all paths
"""
return list_relative_paths(self.external_directory)
def __str__(self):
# This returns the whole path (since we don't know where the directory started)
# which exposes the sandbox directory; we will have to assume for the time being
# that people will not abuse __str__.
return self.external_directory
def _get_underlying_directory(self) -> str:
""" Returns the underlying (real) file system directory this
object refers to. """
return self.external_directory
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