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Pure python reimplementation of .cpio.xz content extraction from pbzx file payload for OS X packages
# 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
# Example usage:
# parse_pbzx('PayloadJava', 'PayloadJava.cpio.xz')
# Updated for speeeeeeeeeeeeed
import struct
def parse_pbzx(pbzx_path, xar_out_path):
with open(pbzx_path, 'rb') as f:
with open(xar_out_path, 'wb') as g:
real_magic = '\xfd7zXZ\x00'
magic = f.read(4)
if magic != 'pbzx':
raise Exception("Error: Not a pbzx file")
# Read 8 bytes for initial flags
tmp = f.read(8)
# Interpret the flags as a 64-bit big-endian unsigned int
flags = struct.unpack('>Q', tmp)[0]
xar_f = open(xar_out_path, 'wb')
while (flags & (1 << 24)):
# Read in more flags
tmp1 = f.read(8)
if len(tmp1) < 8:
# We're at the end!
break
flags = struct.unpack('>Q', tmp1)[0]
# Read in length
tmp2 = f.read(8)
f_length = struct.unpack('>Q', tmp2)[0]
xzmagic = f.read(6)
if xzmagic != real_magic:
raise Exception("Error: Header is not xar file header")
f.seek(-6, 1)
g.write(f.read(f_length))
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