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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 shutil
import stat
from .directory import Directory, VirtualDirectoryError, _FileType
from .. import utils
from ..utils import link_files, copy_files, list_relative_paths, _get_link_mtime, BST_ARBITRARY_TIMESTAMP
from ..utils import _set_deterministic_user, _set_deterministic_mtime
from ..utils import FileListResult
from .._exceptions import ImplError
# FileBasedDirectory intentionally doesn't call its superclass constuctor,
# which is meant to be unimplemented.
# pylint: disable=super-init-not-called
class FileBasedDirectory(Directory):
def __init__(self, external_directory=None, *, parent=None):
self.external_directory = external_directory
self.parent = parent
def descend(self, *paths, create=False, follow_symlinks=False):
""" See superclass Directory for arguments """
current_dir = self
for path in paths:
# Skip empty path segments
if not path:
continue
if path == ".":
continue
if path == "..":
if current_dir.parent is not None:
current_dir = current_dir.parent
# In POSIX /.. == / so just stay at the root dir
continue
new_path = os.path.join(current_dir.external_directory, path)
try:
st = os.lstat(new_path)
if stat.S_ISDIR(st.st_mode):
current_dir = FileBasedDirectory(new_path, parent=current_dir)
elif follow_symlinks and stat.S_ISLNK(st.st_mode):
linklocation = os.readlink(new_path)
newpaths = linklocation.split(os.path.sep)
if os.path.isabs(linklocation):
current_dir = current_dir._find_root().descend(*newpaths, follow_symlinks=True)
else:
current_dir = current_dir.descend(*newpaths, follow_symlinks=True)
else:
raise VirtualDirectoryError(
"Cannot descend into '{}': '{}' is not a directory".format(path, new_path),
reason="not-a-directory",
)
except FileNotFoundError:
if create:
os.mkdir(new_path)
current_dir = FileBasedDirectory(new_path, parent=current_dir)
else:
raise VirtualDirectoryError("Cannot descend into '{}': '{}' does not exist".format(path, new_path))
return current_dir
def import_files(
self,
external_pathspec,
*,
filter_callback=None,
report_written=True,
update_mtime=None,
can_link=False,
properties=None
):
""" See superclass Directory for arguments """
from ._casbaseddirectory import CasBasedDirectory # pylint: disable=cyclic-import
if isinstance(external_pathspec, CasBasedDirectory):
if can_link:
actionfunc = utils.safe_link
else:
actionfunc = utils.safe_copy
import_result = FileListResult()
self._import_files_from_cas(
external_pathspec, actionfunc, filter_callback, update_mtime=update_mtime, result=import_result,
)
else:
if isinstance(external_pathspec, Directory):
source_directory = external_pathspec.external_directory
else:
source_directory = external_pathspec
if can_link and not update_mtime:
import_result = link_files(
source_directory,
self.external_directory,
filter_callback=filter_callback,
ignore_missing=False,
report_written=report_written,
)
else:
import_result = copy_files(
source_directory,
self.external_directory,
filter_callback=filter_callback,
ignore_missing=False,
report_written=report_written,
)
if update_mtime:
for f in import_result.files_written:
os.utime(os.path.join(self.external_directory, f), times=(update_mtime, update_mtime))
return import_result
def import_single_file(self, external_pathspec, properties=None):
dstpath = os.path.join(self.external_directory, os.path.basename(external_pathspec))
result = FileListResult()
if os.path.exists(dstpath):
result.ignored.append(dstpath)
else:
shutil.copyfile(external_pathspec, dstpath, follow_symlinks=False)
return result
def _mark_changed(self):
pass
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, tarfile, destination_dir, mtime=BST_ARBITRARY_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(destination_dir, filename)
tarinfo = tarfile.gettarinfo(source_name, arcname)
tarinfo.mtime = mtime
tarinfo.uid = 0
tarinfo.gid = 0
tarinfo.uname = ""
tarinfo.gname = ""
if tarinfo.isreg():
with open(source_name, "rb") as f:
tarfile.addfile(tarinfo, f)
elif tarinfo.isdir():
tarfile.addfile(tarinfo)
self.descend(*filename.split(os.path.sep)).export_to_tar(tarfile, arcname, mtime)
else:
tarfile.addfile(tarinfo)
def is_empty(self):
it = os.scandir(self.external_directory)
return next(it, None) is None
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)) != BST_ARBITRARY_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 get_size(self):
return utils._get_dir_size(self.external_directory)
def stat(self, *path, follow_symlinks=False):
subdir = self.descend(*path[:-1], follow_symlinks=follow_symlinks)
newpath = os.path.join(subdir.external_directory, path[-1])
st = os.lstat(newpath)
if follow_symlinks and stat.S_ISLNK(st.st_mode):
linklocation = os.readlink(newpath)
newpath = linklocation.split(os.path.sep)
if os.path.isabs(linklocation):
return subdir._find_root().stat(*newpath, follow_symlinks=True)
return subdir.stat(*newpath, follow_symlinks=True)
else:
return st
def exists(self, *path, follow_symlinks=False):
try:
self.stat(*path, follow_symlinks=follow_symlinks)
return True
except (VirtualDirectoryError, FileNotFoundError):
return False
def file_digest(self, *path):
# Use descend() to avoid following symlinks (potentially escaping the sandbox)
subdir = self.descend(*path[:-1])
if subdir.exists(path[-1]) and not subdir.isfile(path[-1]):
raise VirtualDirectoryError("Unsupported file type for digest")
newpath = os.path.join(subdir.external_directory, path[-1])
return utils.sha256sum(newpath)
def readlink(self, *path):
# Use descend() to avoid following symlinks (potentially escaping the sandbox)
subdir = self.descend(*path[:-1])
if subdir.exists(path[-1]) and not subdir.islink(path[-1]):
raise VirtualDirectoryError("Unsupported file type for readlink")
newpath = os.path.join(subdir.external_directory, path[-1])
return os.readlink(newpath)
def open_file(self, *path: str, mode: str = "r"):
# Use descend() to avoid following symlinks (potentially escaping the sandbox)
subdir = self.descend(*path[:-1])
newpath = os.path.join(subdir.external_directory, path[-1])
if mode not in ["r", "rb", "w", "wb", "w+", "w+b", "x", "xb", "x+", "x+b"]:
raise ValueError("Unsupported mode: `{}`".format(mode))
if "b" in mode:
encoding = None
else:
encoding = "utf-8"
if "r" in mode:
return open(newpath, mode=mode, encoding=encoding)
else:
if "x" in mode:
# This check is not atomic, however, we're operating with a
# single thread in a private directory tree.
if subdir.exists(path[-1]):
raise FileExistsError("{} already exists in {}".format(path[-1], str(subdir)))
mode = "w" + mode[1:]
return utils.save_file_atomic(newpath, mode=mode, encoding=encoding)
def remove(self, *path, recursive=False):
# Use descend() to avoid following symlinks (potentially escaping the sandbox)
subdir = self.descend(*path[:-1])
newpath = os.path.join(subdir.external_directory, path[-1])
if subdir._get_filetype(path[-1]) == _FileType.DIRECTORY:
if recursive:
shutil.rmtree(newpath)
else:
os.rmdir(newpath)
else:
os.unlink(newpath)
def rename(self, src, dest):
# Use descend() to avoid following symlinks (potentially escaping the sandbox)
srcdir = self.descend(*src[:-1])
destdir = self.descend(*dest[:-1])
srcpath = os.path.join(srcdir.external_directory, src[-1])
destpath = os.path.join(destdir.external_directory, dest[-1])
if destdir.exists(dest[-1]):
destdir.remove(dest[-1])
os.rename(srcpath, destpath)
def __iter__(self):
yield from os.listdir(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
def _find_root(self):
""" Finds the root of this directory tree by following 'parent' until there is
no parent. """
if self.parent:
return self.parent._find_root()
else:
return self
def _get_filetype(self, name=None):
path = self.external_directory
if name:
path = os.path.join(path, name)
st = os.lstat(path)
if stat.S_ISDIR(st.st_mode):
return _FileType.DIRECTORY
elif stat.S_ISLNK(st.st_mode):
return _FileType.SYMLINK
elif stat.S_ISREG(st.st_mode):
return _FileType.REGULAR_FILE
else:
return _FileType.SPECIAL_FILE
def _import_files_from_cas(
self, source_directory, actionfunc, filter_callback, *, path_prefix="", update_mtime=None, result
):
""" Import files from a CAS-based directory. """
for name, entry in source_directory.index.items():
# The destination filename, relative to the root where the import started
relative_pathname = os.path.join(path_prefix, name)
# The full destination path
dest_path = os.path.join(self.external_directory, name)
is_dir = entry.type == _FileType.DIRECTORY
if is_dir:
src_subdir = source_directory.descend(name)
try:
create_subdir = not os.path.lexists(dest_path)
dest_subdir = self.descend(name, create=create_subdir)
except VirtualDirectoryError:
filetype = self._get_filetype(name)
raise VirtualDirectoryError(
"Destination is a {}, not a directory: /{}".format(filetype, relative_pathname)
)
dest_subdir._import_files_from_cas(
src_subdir,
actionfunc,
filter_callback,
path_prefix=relative_pathname,
result=result,
update_mtime=update_mtime,
)
if filter_callback and not filter_callback(relative_pathname):
if is_dir and create_subdir and dest_subdir.is_empty():
# Complete subdirectory has been filtered out, remove it
os.rmdir(dest_subdir.external_directory)
# Entry filtered out, move to next
continue
if not is_dir:
if os.path.lexists(dest_path):
# Collect overlaps
if not os.path.isdir(dest_path):
result.overwritten.append(relative_pathname)
if not utils.safe_remove(dest_path):
result.ignored.append(relative_pathname)
continue
if entry.type == _FileType.REGULAR_FILE:
src_path = source_directory.cas_cache.objpath(entry.digest)
# fallback to copying if we require mtime support on this file
if update_mtime or entry.node_properties:
utils.safe_copy(src_path, dest_path, result=result)
mtime = update_mtime
# mtime property will override specified mtime
# see https://github.com/bazelbuild/remote-apis/blob/master/build/bazel/remote/execution/v2/nodeproperties.md
# for supported node property specifications
if entry.node_properties:
for prop in entry.node_properties:
if prop.name == "MTime" and prop.value:
mtime = utils._parse_timestamp(prop.value)
else:
raise ImplError("{} is not a supported node property.".format(prop.name))
if mtime:
utils._set_file_mtime(dest_path, mtime)
else:
actionfunc(src_path, dest_path, result=result)
if entry.is_executable:
os.chmod(
dest_path,
stat.S_IRUSR
| stat.S_IWUSR
| stat.S_IXUSR
| stat.S_IRGRP
| stat.S_IXGRP
| stat.S_IROTH
| stat.S_IXOTH,
)
else:
assert entry.type == _FileType.SYMLINK
os.symlink(entry.target, dest_path)
result.files_written.append(relative_pathname)
|