"""The SQlite blob file-like object."""
import os
from dfvfs.file_io import file_io
from dfvfs.lib import errors
from dfvfs.lib import sqlite_database
from dfvfs.resolver import resolver
[docs]
class SQLiteBlobFile(file_io.FileIO):
"""File input/output (IO) object using sqlite."""
_OPERATORS = frozenset(["==", "=", "IS"])
[docs]
def __init__(self, resolver_context, path_spec):
"""Initializes the file-like object.
Args:
resolver_context (Context): resolver context.
path_spec (PathSpec): a path specification.
"""
super().__init__(resolver_context, path_spec)
self._blob = None
self._current_offset = 0
self._database_object = None
self._number_of_rows = None
self._size = 0
self._table_name = None
def _Close(self):
"""Closes the file-like object."""
if self._database_object:
self._database_object.Close()
self._blob = None
self._current_offset = 0
self._size = 0
self._table_name = None
def _Open(self):
"""Opens the file-like object defined by path specification.
Raises:
AccessError: if the access to open the file was denied.
OSError: if the file-like object could not be opened.
PathSpecError: if the path specification is incorrect.
"""
if not self._path_spec.HasParent():
raise errors.PathSpecError("Unsupported path specification without parent.")
table_name = getattr(self._path_spec, "table_name", None)
if table_name is None:
raise errors.PathSpecError("Path specification missing table name.")
column_name = getattr(self._path_spec, "column_name", None)
if column_name is None:
raise errors.PathSpecError("Path specification missing column name.")
row_condition = getattr(self._path_spec, "row_condition", None)
if row_condition:
if not isinstance(row_condition, tuple) or len(row_condition) != 3:
raise errors.PathSpecError(
"Unsupported row_condition not a tuple in the form: "
"(column_name, operator, value)."
)
row_index = getattr(self._path_spec, "row_index", None)
if row_index is not None and not isinstance(row_index, int):
raise errors.PathSpecError("Unsupported row_index not of integer type.")
if not row_condition and row_index is None:
raise errors.PathSpecError(
"Path specification requires either a row_condition or row_index."
)
if self._database_object:
raise OSError("Database file already set.")
file_object = resolver.Resolver.OpenFileObject(
self._path_spec.parent, resolver_context=self._resolver_context
)
database_object = sqlite_database.SQLiteDatabaseFile()
database_object.Open(file_object)
# Sanity check the table and column names.
rows = []
error_string = ""
if not database_object.HasTable(table_name):
error_string = f"Missing table: {table_name:s}"
elif not database_object.HasColumn(table_name, column_name):
error_string = f"Missing column: {column_name:s} in table: {table_name:s}"
elif not row_condition:
query = (
f"SELECT {column_name:s} FROM {table_name:s} LIMIT 1 "
f"OFFSET {row_index:d}"
)
rows = database_object.Query(query)
elif not database_object.HasColumn(table_name, row_condition[0]):
condition_column_name = row_condition[0]
error_string = (
f"Missing row condition column: {condition_column_name:s} in table: "
f"{table_name:s}"
)
elif row_condition[1] not in self._OPERATORS:
condition_operator = row_condition[1]
error_string = (
f"Unsupported row condition operator: {condition_operator:s}."
)
else:
condition_column_name = row_condition[0]
condition_operator = row_condition[1]
query = (
f"SELECT {column_name:s} FROM {table_name:s} "
f"WHERE {condition_column_name:s} {condition_operator:s} ?"
)
rows = database_object.Query(query, parameters=(row_condition[2],))
# Make sure the query returns a single row, using cursor.rowcount
# is not reliable for this purpose.
if not error_string and (len(rows) != 1 or len(rows[0]) != 1):
if not row_condition:
error_string = (
f"Unable to open blob in table: {table_name:s} and column: "
f"{column_name:s} for row: {row_index:d}."
)
else:
row_condition_string = " ".join(
[f"{value!s}" for value in iter(row_condition)]
)
error_string = (
f"Unable to open blob in table: {table_name:s} and column: "
f"{column_name:s} where: {row_condition_string:s}."
)
if error_string:
database_object.Close()
raise OSError(error_string)
self._blob = rows[0][0]
self._current_offset = 0
self._database_object = database_object
self._size = len(self._blob)
self._table_name = table_name
# TODO: remove this when there is a move this to a central temp file
# manager. https://github.com/log2timeline/dfvfs/issues/92
[docs]
def GetNumberOfRows(self):
"""Retrieves the number of rows of the table.
Returns:
int: number of rows.
Raises:
OSError: if the file-like object has not been opened.
"""
if not self._database_object:
raise OSError("Not opened.")
if self._number_of_rows is None:
self._number_of_rows = self._database_object.GetNumberOfRows(
self._table_name
)
return self._number_of_rows
# Note: that the following functions do not follow the style guide
# because they are part of the file-like object interface.
# pylint: disable=invalid-name
[docs]
def read(self, size=None):
"""Reads a byte string from the file-like object at the current offset.
The function will read a byte string of the specified size or
all of the remaining data if no size was specified.
Args:
size (Optional[int]): number of bytes to read, where None is all
remaining data.
Returns:
bytes: data read.
Raises:
OSError: if the read failed.
"""
if not self._database_object:
raise OSError("Not opened.")
if self._current_offset < 0:
raise OSError("Invalid offset value out of bounds.")
if size == 0 or self._current_offset >= self._size:
return b""
if size is None:
size = self._size
if self._current_offset + size > self._size:
size = self._size - self._current_offset
start_offset = self._current_offset
self._current_offset += size
return self._blob[start_offset : self._current_offset]
[docs]
def seek(self, offset, whence=os.SEEK_SET):
"""Seeks to an offset within the file-like object.
Args:
offset (int): offset to seek to.
whence (Optional(int)): value that indicates whether offset is an absolute
or relative position within the file.
Raises:
OSError: if the seek failed.
"""
if not self._database_object:
raise OSError("Not opened.")
if whence == os.SEEK_CUR:
offset += self._current_offset
elif whence == os.SEEK_END:
offset += self._size
elif whence != os.SEEK_SET:
raise OSError("Unsupported whence.")
if offset < 0:
raise OSError("Invalid offset value out of bounds.")
self._current_offset = offset
[docs]
def get_offset(self):
"""Retrieves the current offset into the file-like object.
Returns:
int: current offset into the file-like object.
Raises:
OSError: if the file-like object has not been opened.
"""
if not self._database_object:
raise OSError("Not opened.")
return self._current_offset
[docs]
def get_size(self):
"""Retrieves the size of the file-like object.
Returns:
int: size of the file-like object data.
Raises:
OSError: if the file-like object has not been opened.
"""
if not self._database_object:
raise OSError("Not opened.")
return self._size