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#!/usr/bin/env python
# This code is from https://gist.github.com/pudquick/ff412bcb29c9c1fa4b8d
#
# v2 pbzx stream handler
# My personal writeup on the differences here:
# https://gist.github.com/pudquick/29fcfe09c326a9b96cf5
#
# Pure python reimplementation of .cpio.xz content extraction from pbzx file
# payload originally here:
# http://www.tonymacx86.com/general-help/135458-pbzx-stream-parser.html
#
# Cleaned up C version (as the basis for my code) here, thanks to Pepijn Bruienne / @bruienne
# https://gist.github.com/bruienne/029494bbcfb358098b41
#
# The python version of this code does not have an explicit license, but
# is based on GPLv3 C code linked above.
#
# This program 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, either version 3 of the License, or
# (at your option) any later version.
#
# This program 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 this program. If not, see <https://www.gnu.org/licenses/>.
from __future__ import absolute_import
import struct
import sys
def seekread(f, offset=None, length=0, relative=True):
if offset is not None:
# offset provided, let's seek
f.seek(offset, [0, 1, 2][relative])
if length != 0:
return f.read(length)
def parse_pbzx(pbzx_path):
section = 0
xar_out_path = "%s.part%02d.cpio.xz" % (pbzx_path, section)
f = open(pbzx_path, "rb")
# pbzx = f.read()
# f.close()
magic = seekread(f, length=4)
if magic != "pbzx":
raise "Error: Not a pbzx file"
# Read 8 bytes for initial flags
flags = seekread(f, length=8)
# Interpret the flags as a 64-bit big-endian unsigned int
flags = struct.unpack(">Q", flags)[0]
xar_f = open(xar_out_path, "wb")
while flags & (1 << 24):
# Read in more flags
flags = seekread(f, length=8)
flags = struct.unpack(">Q", flags)[0]
# Read in length
f_length = seekread(f, length=8)
f_length = struct.unpack(">Q", f_length)[0]
xzmagic = seekread(f, length=6)
if xzmagic != "\xfd7zXZ\x00":
# This isn't xz content, this is actually _raw decompressed cpio_
# chunk of 16MB in size...
# Let's back up ...
seekread(f, offset=-6, length=0)
# ... and split it out ...
f_content = seekread(f, length=f_length)
section += 1
decomp_out = "%s.part%02d.cpio" % (pbzx_path, section)
g = open(decomp_out, "wb")
g.write(f_content)
g.close()
# Now to start the next section, which should hopefully be .xz
# (we'll just assume it is ...)
xar_f.close()
section += 1
new_out = "%s.part%02d.cpio.xz" % (pbzx_path, section)
xar_f = open(new_out, "wb")
else:
f_length -= 6
# This part needs buffering
f_content = seekread(f, length=f_length)
tail = seekread(f, offset=-2, length=2)
xar_f.write(xzmagic)
xar_f.write(f_content)
if tail != "YZ":
xar_f.close()
raise "Error: Footer is not xar file footer"
try:
f.close()
xar_f.close()
except BaseException:
pass
def main():
parse_pbzx(sys.argv[1])
if __name__ == "__main__":
main()
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