Initial commit

README.md

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+Simple script(s) to extract from XCode .xip files.
+
+These files are simple enough to extract in simple python without dragging in
+dependencies.
+
+This is a working POC. The code is sloppy and there is very little error
+handling, but it works for all files tested.
+
+It contains a very simple python port of [pbzx](https://github.com/NiklasRosenstein/pbzx), thank you to NiklasRosenstein
+and PHPdev32.
+
+### Usage:
+./extract_xcode.py -f Xcode_*.xip | cpio -d -i
+
+### Maintainer Wanted
+
+Please feel free to fork and rewrite it into a more generally useful tool.

extract_xcode.py

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+#!/usr/bin/env python3
+# Copyright (c) 2020 The Bitcoin Core developers
+# Distributed under the MIT software license, see the accompanying
+# file COPYING or http://www.opensource.org/licenses/mit-license.php.
+
+"""XCode extractor
+"""
+
+import argparse
+import sys
+import struct
+import zlib
+import xml.etree.ElementTree as ET
+import bz2
+import lzma
+
+XAR_MAGIC = b'\x78\x61\x72\x21'
+PBZX_MAGIC = b'\x70\x62\x7a\x78'
+LZMA_MAGIC = b'\xfd\x37\x7a\x58\x5a\x00'
+
+class io_wrapper(object):
+    """Helper for stdin/stdout binary weirdness"""
+    def __init__(self, filename, mode):
+        self.filename = filename
+        self.mode = mode
+    def __enter__(self):
+        if self.filename == '-':
+            if self.mode is None or self.mode == '' or 'r' in self.mode:
+                self.fh = sys.stdin
+            else:
+                self.fh = sys.stdout
+        else:
+            self.fh = open(self.filename, self.mode)
+        return self
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        if self.filename is not '-':
+            self.fh.close()
+    def write(self, bytes):
+        if self.filename is not '-':
+            return self.fh.write(bytes)
+        return self.fh.buffer.write(bytes)
+    def read(self, size):
+        if self.filename is not '-':
+            return self.fh.read(size)
+        return self.fh.buffer.read(size)
+    def seek(self, size):
+        return self.fh.seek(size)
+
+def run():
+    parser = argparse.ArgumentParser(
+        description=__doc__, formatter_class=argparse.RawTextHelpFormatter)
+
+    parser.add_argument("-f", '--file', nargs='?', default="-")
+    parser.add_argument('outfile', nargs='?', default="-")
+
+    args = parser.parse_args()
+
+    with io_wrapper(args.file, "rb") as infile, io_wrapper(args.outfile, "wb") as outfile:
+
+        start_offset = 0
+        magic = infile.read(4)
+        if magic != XAR_MAGIC:
+            print("bad xar magic", file=sys.stderr)
+            sys.exit(1)
+
+        bytes = infile.read(24)
+        header_size, xar_version, toc_compressed, toc_uncompressed, checksum_type = struct.unpack('>HHQQI', bytes)
+        start_offset += header_size
+        start_offset += toc_compressed
+        bytes = infile.read(toc_compressed)
+
+        xml_toc = zlib.decompress(bytes).decode("utf-8") 
+
+        root = ET.fromstring(xml_toc)
+
+        content_offset = 0
+        content_length = 0
+        content_encoding = ""
+
+        toc = root.find("toc")
+        for elem in toc.findall("file"):
+            name = elem.find("name").text
+            if name == "Content":
+                data = elem.find("data")
+                content_offset = int(data.find("offset").text)
+                content_length = int(data.find("length").text)
+                content_encoding = data.find("encoding").get("style")
+                content_uncompressed_length = int(data.find("size").text)
+                found_content = True
+                break
+
+        if (content_length == 0):
+            print("No \"Content\" file to extract.", file=sys.stderr)
+            sys.exit(1)
+
+        infile.seek(content_offset + start_offset)
+
+        content_read_size = 0
+
+        magic = infile.read(4)
+        content_read_size += 4
+        if magic != PBZX_MAGIC:
+            print("bad pbzx magic", file=sys.stderr)
+            sys.exit(2)
+
+        bytes = infile.read(8)
+        content_read_size += 8
+        flags, = struct.unpack('>Q', bytes)
+        bytes = infile.read(16)
+        content_read_size += 16
+        while (flags & 1 << 24):
+            flags, size = struct.unpack('>QQ', bytes)
+            bytes = infile.read(size)
+            content_read_size += size
+            compressed = size != 1 << 24
+            if compressed:
+                if bytes[0:6] != LZMA_MAGIC:
+                    print("bad lzma magic: ", file=sys.stderr)
+                    sys.exit(3)
+                outfile.write(lzma.decompress(bytes))
+            else:
+                outfile.write(bytes)
+
+            if content_read_size == content_length:
+                break
+
+            bytes = infile.read(16)
+            content_read_size += 16
+
+if __name__ == '__main__':
+    run()