"""The EXT file system implementation."""
import pyfsext
from dfvfs.lib import definitions
from dfvfs.lib import errors
from dfvfs.path import ext_path_spec
from dfvfs.resolver import resolver
from dfvfs.vfs import file_system
from dfvfs.vfs import ext_file_entry
[docs]
class EXTFileSystem(file_system.FileSystem):
"""File system that uses pyfsext."""
ROOT_DIRECTORY_INODE_NUMBER = 2
TYPE_INDICATOR = definitions.TYPE_INDICATOR_EXT
[docs]
def __init__(self, resolver_context, path_spec):
"""Initializes an EXT file system.
Args:
resolver_context (Context): resolver context.
path_spec (PathSpec): a path specification.
"""
super().__init__(resolver_context, path_spec)
self._file_object = None
self._fsext_volume = None
def _Close(self):
"""Closes the file system.
Raises:
OSError: if the close failed.
"""
self._fsext_volume = 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.
Raises:
AccessError: if the access to open the file was denied.
OSError: if the file system object 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
)
fsext_volume = pyfsext.volume()
fsext_volume.open_file_object(file_object)
self._file_object = file_object
self._fsext_volume = fsext_volume
[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.
Raises:
BackEndError: if the file entry cannot be opened.
"""
# Opening a file by inode is faster than opening a file by location.
fsext_file_entry = None
location = getattr(path_spec, "location", None)
inode = getattr(path_spec, "inode", None)
try:
if inode is not None:
fsext_file_entry = self._fsext_volume.get_file_entry_by_inode(inode)
elif location is not None:
fsext_file_entry = self._fsext_volume.get_file_entry_by_path(location)
except OSError as exception:
raise errors.BackEndError(exception)
return fsext_file_entry is not None
[docs]
def GetFileEntryByPathSpec(self, path_spec):
"""Retrieves a file entry for a path specification.
Args:
path_spec (PathSpec): path specification.
Returns:
EXTFileEntry: file entry or None if not available.
Raises:
BackEndError: if the file entry cannot be opened.
"""
# Opening a file by inode is faster than opening a file by location.
fsext_file_entry = None
location = getattr(path_spec, "location", None)
inode = getattr(path_spec, "inode", None)
if location == self.LOCATION_ROOT or inode == self.ROOT_DIRECTORY_INODE_NUMBER:
fsext_file_entry = self._fsext_volume.get_root_directory()
return ext_file_entry.EXTFileEntry(
self._resolver_context,
self,
path_spec,
fsext_file_entry=fsext_file_entry,
is_root=True,
)
try:
if inode is not None:
fsext_file_entry = self._fsext_volume.get_file_entry_by_inode(inode)
elif location is not None:
fsext_file_entry = self._fsext_volume.get_file_entry_by_path(location)
except OSError as exception:
raise errors.BackEndError(exception)
if fsext_file_entry is None:
return None
return ext_file_entry.EXTFileEntry(
self._resolver_context, self, path_spec, fsext_file_entry=fsext_file_entry
)
[docs]
def GetEXTFileEntryByPathSpec(self, path_spec):
"""Retrieves the EXT file entry for a path specification.
Args:
path_spec (PathSpec): a path specification.
Returns:
pyfsext.file_entry: file entry.
Raises:
PathSpecError: if the path specification is missing location and
inode.
"""
# Opening a file by inode is faster than opening a file by location.
location = getattr(path_spec, "location", None)
inode = getattr(path_spec, "inode", None)
if inode is not None:
fsext_file_entry = self._fsext_volume.get_file_entry_by_inode(inode)
elif location is not None:
fsext_file_entry = self._fsext_volume.get_file_entry_by_path(location)
else:
raise errors.PathSpecError("Path specification missing location and inode.")
return fsext_file_entry
[docs]
def GetRootFileEntry(self):
"""Retrieves the root file entry.
Returns:
EXTFileEntry: file entry.
"""
path_spec = ext_path_spec.EXTPathSpec(
location=self.LOCATION_ROOT,
inode=self.ROOT_DIRECTORY_INODE_NUMBER,
parent=self._path_spec.parent,
)
return self.GetFileEntryByPathSpec(path_spec)