Current File : //lib/python3/dist-packages/duplicity/librsync.py
# -*- Mode:Python; indent-tabs-mode:nil; tab-width:4; encoding:utf-8 -*-
#
# Copyright 2002 Ben Escoto <ben@emerose.org>
# Copyright 2007 Kenneth Loafman <kenneth@loafman.com>
#
# This file is part of duplicity.
#
# duplicity is free software; you can redistribute it and/or modify
# under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 2 of the License, or
# (at your option) any later version.
#
# duplicity 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
# General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with duplicity; if not, write to the Free Software Foundation,
# Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
"""Provides a high-level interface to some librsync functions
This is a python wrapper around the lower-level _librsync module,
which is written in C. The goal was to use C as little as possible...
"""
import array
import os
from . import _librsync
if os.environ.get("READTHEDOCS") == "True":
import unittest.mock as mock
import duplicity
duplicity._librsync = mock.MagicMock()
blocksize = _librsync.RS_JOB_BLOCKSIZE
class librsyncError(Exception):
"""Signifies error in internal librsync processing (bad signature, etc.)
underlying _librsync.librsyncError's are regenerated using this
class because the C-created exceptions are by default
unPickleable. There is probably a way to fix this in _librsync,
but this scheme was easier.
"""
pass
class LikeFile(object):
"""File-like object used by SigFile, DeltaFile, and PatchFile"""
mode = "rb"
# This will be replaced in subclasses by an object with
# appropriate cycle() method
maker = None
def __init__(self, infile, need_seek=None):
"""LikeFile initializer - zero buffers, set eofs off"""
self.check_file(infile, need_seek)
self.infile = infile
self.closed = self.infile_closed = None
self.inbuf = b""
self.outbuf = array.array("b")
self.eof = self.infile_eof = None
def check_file(self, file, need_seek=None):
"""Raise type error if file doesn't have necessary attributes"""
if not hasattr(file, "read"):
raise TypeError("Basis file must have a read() method")
if not hasattr(file, "close"):
raise TypeError("Basis file must have a close() method")
if need_seek and not hasattr(file, "seek"):
raise TypeError("Basis file must have a seek() method")
def read(self, length=-1):
"""Build up self.outbuf, return first length bytes"""
if length == -1:
while not self.eof:
self._add_to_outbuf_once()
real_len = len(self.outbuf)
else:
while not self.eof and len(self.outbuf) < length:
self._add_to_outbuf_once()
real_len = min(length, len(self.outbuf))
return_val = self.outbuf[:real_len].tobytes()
del self.outbuf[:real_len]
return return_val
def _add_to_outbuf_once(self):
"""Add one cycle's worth of output to self.outbuf"""
if not self.infile_eof:
self._add_to_inbuf()
try:
self.eof, len_inbuf_read, cycle_out = self.maker.cycle(self.inbuf)
except _librsync.librsyncError as e:
raise librsyncError(str(e))
self.inbuf = self.inbuf[len_inbuf_read:]
self.outbuf.frombytes(cycle_out)
def _add_to_inbuf(self):
"""Make sure len(self.inbuf) >= blocksize"""
assert not self.infile_eof
while len(self.inbuf) < blocksize:
new_in = self.infile.read(blocksize)
if not new_in:
self.infile_eof = 1
assert not self.infile.close()
self.infile_closed = 1
break
self.inbuf += new_in
def close(self):
"""Close infile"""
if not self.infile_closed:
assert not self.infile.close()
self.closed = 1
class SigFile(LikeFile):
"""File-like object which incrementally generates a librsync signature"""
def __init__(self, infile, blocksize=_librsync.RS_DEFAULT_BLOCK_LEN):
"""SigFile initializer - takes basis file
basis file only needs to have read() and close() methods. It
will be closed when we come to the end of the signature.
"""
LikeFile.__init__(self, infile)
try:
self.maker = _librsync.new_sigmaker(blocksize)
except _librsync.librsyncError as e:
raise librsyncError(str(e))
class DeltaFile(LikeFile):
"""File-like object which incrementally generates a librsync delta"""
def __init__(self, signature, new_file):
"""DeltaFile initializer - call with signature and new file
Signature can either be a string or a file with read() and
close() methods. New_file also only needs to have read() and
close() methods. It will be closed when self is closed.
"""
LikeFile.__init__(self, new_file)
if isinstance(signature, bytes):
sig_string = signature
else:
self.check_file(signature)
sig_string = signature.read()
assert not signature.close()
try:
self.maker = _librsync.new_deltamaker(sig_string)
except _librsync.librsyncError as e:
raise librsyncError(str(e))
class PatchedFile(LikeFile):
"""File-like object which applies a librsync delta incrementally"""
def __init__(self, basis_file, delta_file):
"""PatchedFile initializer - call with basis delta
Here basis_file must be a true Python file, because we may
need to seek() around in it a lot, and this is done in C.
delta_file only needs read() and close() methods.
"""
LikeFile.__init__(self, delta_file)
try:
basis_file.fileno()
except Exception as e:
"""tempfile.TemporaryFile() only guarantees a true file
object on posix platforms. on cygwin/windows a file-like
object whose file attribute is the underlying true file
object is returned.
"""
if hasattr(basis_file, "file") and hasattr(basis_file.file, "fileno"):
basis_file = basis_file.file
else:
raise TypeError(
_(
"basis_file must be a (true) file or an object whose "
"file attribute is the underlying true file object"
)
)
try:
self.maker = _librsync.new_patchmaker(basis_file)
except _librsync.librsyncError as e:
raise librsyncError(str(e))
class SigGenerator(object):
"""Calculate signature.
Input and output is same as SigFile, but the interface is like md5
module, not filelike object
"""
def __init__(self, blocksize=_librsync.RS_DEFAULT_BLOCK_LEN):
"""Return new signature instance"""
try:
self.sig_maker = _librsync.new_sigmaker(blocksize)
except _librsync.librsyncError as e:
raise librsyncError(str(e))
self.gotsig = None
self.buffer = b""
self.sigstring_list = []
def update(self, buf):
"""Add buf to data that signature will be calculated over"""
if self.gotsig:
raise librsyncError("SigGenerator already provided signature")
self.buffer += buf
while len(self.buffer) >= blocksize:
if self.process_buffer():
raise librsyncError("Premature EOF received from sig_maker")
def process_buffer(self):
"""Run self.buffer through sig_maker, add to self.sig_string"""
try:
eof, len_buf_read, cycle_out = self.sig_maker.cycle(self.buffer)
except _librsync.librsyncError as e:
raise librsyncError(str(e))
self.buffer = self.buffer[len_buf_read:]
self.sigstring_list.append(cycle_out)
return eof
def getsig(self):
"""Return signature over given data"""
while not self.process_buffer():
pass # keep running until eof
return b"".join(self.sigstring_list)
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