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# Copyright 2002 Ben Escoto
#
# This file is part of rdiff-backup.
#
# rdiff-backup is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, Inc., 675 Mass Ave, Cambridge MA
# 02139, USA; either version 2 of the License, or (at your option) any
# later version; incorporated herein by reference.
"""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 _librsync, types, array
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:
"""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 = ""
self.outbuf = array.array('c')
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].tostring()
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, e: raise librsyncError(str(e))
self.inbuf = self.inbuf[len_inbuf_read:]
self.outbuf.fromstring(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):
"""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()
except _librsync.librsyncError, 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 type(signature) is types.StringType: 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, 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)
if type(basis_file) is not types.FileType:
raise TypeError("basis_file must be a (true) file")
try: self.maker = _librsync.new_patchmaker(basis_file)
except _librsync.librsyncError, e: raise librsyncError(str(e))
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