# -*- coding: utf-8 -*-
"""The SQLite blob file system implementation."""
from dfvfs.lib import definitions
from dfvfs.lib import errors
from dfvfs.path import sqlite_blob_path_spec
from dfvfs.resolver import resolver
from dfvfs.vfs import sqlite_blob_file_entry
from dfvfs.vfs import file_system
[docs]
class SQLiteBlobFileSystem(file_system.FileSystem):
"""Class that implements a file system object using SQLite blob."""
TYPE_INDICATOR = definitions.TYPE_INDICATOR_SQLITE_BLOB
[docs]
def __init__(self, resolver_context, path_spec):
"""Initializes a file system.
Args:
resolver_context (Context): resolver context.
path_spec (PathSpec): a path specification.
"""
super(SQLiteBlobFileSystem, self).__init__(resolver_context, path_spec)
self._file_object = None
self._number_of_rows = None
def _Close(self):
"""Closes a file system.
Raises:
IOError: if the close failed.
"""
self._file_object = None
self._number_of_rows = None
def _Open(self, mode='rb'):
"""Opens the file system object 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.
IOError: 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)
self._file_object = file_object
[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.
"""
# All checks for correct path spec is done in SQLiteBlobFile.
# Therefore, attempt to open the path specification and
# check if errors occurred.
try:
file_object = resolver.Resolver.OpenFileObject(
path_spec, resolver_context=self._resolver_context)
except (IOError, ValueError, errors.AccessError, errors.PathSpecError):
file_object = None
return bool(file_object)
[docs]
def GetFileEntryByPathSpec(self, path_spec):
"""Retrieves a file entry for a path specification.
Args:
path_spec (PathSpec): path specification.
Returns:
FileEntry: a file entry or None.
"""
row_index = getattr(path_spec, 'row_index', None)
row_condition = getattr(path_spec, 'row_condition', None)
# If no row_index or row_condition is provided, return a directory.
if row_index is None and row_condition is None:
return sqlite_blob_file_entry.SQLiteBlobFileEntry(
self._resolver_context, self, path_spec, is_root=True,
is_virtual=True)
return sqlite_blob_file_entry.SQLiteBlobFileEntry(
self._resolver_context, self, path_spec)
[docs]
def GetRootFileEntry(self):
"""Retrieves the root file entry.
Returns:
FileEntry: a file entry or None.
"""
path_spec = sqlite_blob_path_spec.SQLiteBlobPathSpec(
table_name=self._path_spec.table_name,
column_name=self._path_spec.column_name,
parent=self._path_spec.parent)
return self.GetFileEntryByPathSpec(path_spec)