"""The TAR file system implementation."""
import os
import tarfile
from dfvfs.lib import definitions
from dfvfs.lib import errors
from dfvfs.path import tar_path_spec
from dfvfs.resolver import resolver
from dfvfs.vfs import file_system
from dfvfs.vfs import tar_file_entry
[docs]
class TARFileSystem(file_system.FileSystem):
"""Class that implements a file system using tarfile.
Attributes:
encoding (str): file entry name encoding.
"""
TYPE_INDICATOR = definitions.TYPE_INDICATOR_TAR
[docs]
def __init__(self, resolver_context, path_spec, encoding="utf-8"):
"""Initializes a file system.
Args:
resolver_context (Context): resolver context.
path_spec (PathSpec): a path specification.
encoding (Optional[str]): file entry name encoding.
"""
super().__init__(resolver_context, path_spec)
self._directory_paths = None
self._file_object = None
self._tar_file = None
self.encoding = encoding
def _Close(self):
"""Closes the file system.
Raises:
OSError: if the close failed.
"""
self._tar_file.close()
self._tar_file = None
self._directory_paths = None
self._file_object = None
def _Open(self, mode="rb"):
"""Opens the file system defined by path specification.
Args:
mode (Optional[str]): file access mode. The default is 'rb' which
represents read-only binary.
Raises:
AccessError: if the access to open the file was denied.
OSError: if the file system could not be opened.
PathSpecError: if the path specification is incorrect.
ValueError: if the path specification is invalid.
"""
if not self._path_spec.HasParent():
raise errors.PathSpecError("Unsupported path specification without parent.")
file_object = resolver.Resolver.OpenFileObject(
self._path_spec.parent, resolver_context=self._resolver_context
)
# Set the file offset to 0 because tarfile.open() does not.
file_object.seek(0, os.SEEK_SET)
# Explicitly tell tarfile not to use compression. Compression should be
# handled by the file-like object.
try:
# pylint: disable=consider-using-with
tar_file = tarfile.open(mode="r:", fileobj=file_object)
except tarfile.ReadError as exception:
raise OSError(exception)
self._file_object = file_object
self._tar_file = tar_file
self._directory_paths = set()
for name in self._tar_file.getnames():
if not name:
continue
if name[0] == "/":
name = name[1:]
if name[-1] == "/":
directory_name = name[:-1]
else:
directory_name, _, _ = name.rpartition("/")
if directory_name:
path = ""
for segment in directory_name.split("/"):
if path:
path = f"{path:s}/{segment:s}"
else:
path = f"/{segment:s}"
self._directory_paths.add(path)
[docs]
def FileEntryExistsByPathSpec(self, path_spec):
"""Determines if a file entry for a path specification exists.
Args:
path_spec (PathSpec): path specification.
Returns:
bool: True if the file entry exists.
"""
location = getattr(path_spec, "location", None)
if location is None or not location.startswith(self.LOCATION_ROOT):
return False
if len(location) == 1:
return True
# A tar file can contain paths with and without leading separator.
tar_info = None
is_virtual = False
try:
tar_info = self._tar_file.getmember(location[1:])
except KeyError:
pass
if not tar_info:
try:
# Directories are stored with a trailing separator.
tar_info = self._tar_file.getmember(f"{location[1:]:s}/")
except KeyError:
pass
if not tar_info:
try:
tar_info = self._tar_file.getmember(location)
except KeyError:
pass
if not tar_info:
try:
# Directories are stored with a trailing separator.
tar_info = self._tar_file.getmember(f"{location:s}/")
except KeyError:
pass
if not tar_info:
# Check if location could be a virtual directory.
is_virtual = location in self._directory_paths
return bool(tar_info or is_virtual)
[docs]
def GetFileEntryByPathSpec(self, path_spec):
"""Retrieves a file entry for a path specification.
Args:
path_spec (PathSpec): path specification.
Returns:
TARFileEntry: file entry or None.
"""
if not self.FileEntryExistsByPathSpec(path_spec):
return None
location = getattr(path_spec, "location", None)
if len(location) == 1:
return tar_file_entry.TARFileEntry(
self._resolver_context, self, path_spec, is_root=True, is_virtual=True
)
# A tar file can contain paths with and without leading separator.
tar_info = None
is_virtual = False
try:
tar_info = self._tar_file.getmember(location[1:])
except KeyError:
pass
if not tar_info:
try:
# Directories are stored with a trailing separator.
tar_info = self._tar_file.getmember(f"{location[1:]:s}/")
except KeyError:
pass
if not tar_info:
try:
tar_info = self._tar_file.getmember(location)
except KeyError:
pass
if not tar_info:
try:
# Directories are stored with a trailing separator.
tar_info = self._tar_file.getmember(f"{location:s}/")
except KeyError:
pass
if not tar_info:
# Check if location could be a virtual directory.
is_virtual = location in self._directory_paths
if tar_info or is_virtual:
kwargs = {}
if tar_info:
kwargs["tar_info"] = tar_info
else:
kwargs["is_virtual"] = True
return tar_file_entry.TARFileEntry(
self._resolver_context, self, path_spec, **kwargs
)
return None
[docs]
def GetRootFileEntry(self):
"""Retrieves the root file entry.
Returns:
TARFileEntry: file entry.
"""
path_spec = tar_path_spec.TARPathSpec(
location=self.LOCATION_ROOT, parent=self._path_spec.parent
)
return self.GetFileEntryByPathSpec(path_spec)
[docs]
def GetTARFile(self):
"""Retrieves the TAR file.
Returns:
tarfile.TARFile: TAR file.
"""
return self._tar_file
[docs]
def GetTARInfoByPathSpec(self, path_spec):
"""Retrieves the TAR info for a path specification.
Args:
path_spec (PathSpec): a path specification.
Returns:
tarfile.TARInfo: TAR info or None if it does not exist.
Raises:
PathSpecError: if the path specification is incorrect.
"""
location = getattr(path_spec, "location", None)
if location is None:
raise errors.PathSpecError("Path specification missing location.")
if not location.startswith(self.LOCATION_ROOT):
raise errors.PathSpecError("Invalid location in path specification.")
tar_file = None
if len(location) > 1:
try:
tar_file = self._tar_file.getmember(location[1:])
except KeyError:
pass
return tar_file