From f84188c1dc2a9555d8cead6d2971f968f762690e Mon Sep 17 00:00:00 2001
From: Mike Hommey <mh+mozilla@glandium.org>
Date: Wed, 11 Jan 2023 22:10:14 +0000
Subject: [PATCH] Bug 1809575 - Replace the use of the external xar tool with a
 simple python implementation. r=gsvelto

Differential Revision: https://phabricator.services.mozilla.com/D166504
---
 .../docker/system-symbols-mac/setup.sh        |  6 --
 .../system-symbols/mac/PackageSymbolDumper.py |  7 ++-
 .../system-symbols/mac/macpkg.py              | 57 +++++++++++++++++++
 3 files changed, 61 insertions(+), 9 deletions(-)

diff --git a/taskcluster/docker/system-symbols-mac/setup.sh b/taskcluster/docker/system-symbols-mac/setup.sh
index f1312dcf1b20..c0c4e766acb3 100644
--- a/taskcluster/docker/system-symbols-mac/setup.sh
+++ b/taskcluster/docker/system-symbols-mac/setup.sh
@@ -4,12 +4,6 @@ set -v -e -x
 ncpu=-j$(grep -c ^processor /proc/cpuinfo)
 
 WORK=/setup/
-cd $WORK
-git clone --depth=1 --single-branch -b system-symbols https://github.com/mozilla/xar xar
-cd xar/xar
-./autogen.sh --prefix=/builds/worker
-make "$ncpu" && make install
-
 cd $WORK
 git clone --depth=1 --single-branch -b system-symbols-mac https://github.com/gabrielesvelto/libdmg-hfsplus.git
 cd libdmg-hfsplus
diff --git a/tools/crashreporter/system-symbols/mac/PackageSymbolDumper.py b/tools/crashreporter/system-symbols/mac/PackageSymbolDumper.py
index 47a582454945..5e63a2f39f3a 100755
--- a/tools/crashreporter/system-symbols/mac/PackageSymbolDumper.py
+++ b/tools/crashreporter/system-symbols/mac/PackageSymbolDumper.py
@@ -32,7 +32,6 @@ Required tools for Linux:
     pax
     gzip
     tar
-    xar (http://code.google.com/p/xar/)
     xpwn's dmg (https://github.com/planetbeing/xpwn)
 
 Created on Apr 11, 2012
@@ -50,6 +49,7 @@ import subprocess
 import tempfile
 import traceback
 
+from macpkg import Pbzx, uncpio, unxar
 from scrapesymbols.gathersymbols import process_paths
 
 
@@ -60,7 +60,9 @@ def expand_pkg(pkg_path, out_path):
     @param pkg_path: a path to an installer package (.pkg)
     @param out_path: a path to hold the package contents
     """
-    subprocess.check_call(["xar", "-x", "-C", out_path, "-f", pkg_path])
+    for name, content in unxar(open(pkg_path, "rb")):
+        with open(os.path.join(out_path, name), "wb") as fh:
+            shutil.copyfileobj(content, fh)
 
 
 def expand_dmg(dmg_path, out_path):
@@ -178,7 +180,6 @@ def extract_payload(payload_path, output_path):
             return True
         elif header == b"pb":
             logging.info("Extracting pbzx payload")
-            from macpkg import Pbzx, uncpio
 
             for path, mode, content in uncpio(Pbzx(open(payload_path, "rb"))):
                 if not path or not stat.S_ISREG(mode):
diff --git a/tools/crashreporter/system-symbols/mac/macpkg.py b/tools/crashreporter/system-symbols/mac/macpkg.py
index 0a8a6ec8411c..6cdee015bda5 100644
--- a/tools/crashreporter/system-symbols/mac/macpkg.py
+++ b/tools/crashreporter/system-symbols/mac/macpkg.py
@@ -2,8 +2,65 @@
 # License, v. 2.0. If a copy of the MPL was not distributed with this
 # file, You can obtain one at http://mozilla.org/MPL/2.0/.
 
+import bz2
 import lzma
+import os
 import struct
+import zlib
+from xml.etree.ElementTree import XML
+
+
+def unxar(fileobj):
+    magic = fileobj.read(4)
+    if magic != b"xar!":
+        raise Exception("Not a XAR?")
+
+    header_size = fileobj.read(2)
+    header_size = struct.unpack(">H", header_size)[0]
+    if header_size > 64:
+        raise Exception(
+            f"Don't know how to handle a {header_size} bytes XAR header size"
+        )
+    header_size -= 6  # what we've read so far.
+    header = fileobj.read(header_size)
+    if len(header) != header_size:
+        raise Exception("Failed to read XAR header")
+    (
+        version,
+        compressed_toc_len,
+        uncompressed_toc_len,
+        checksum_type,
+    ) = struct.unpack(">HQQL", header[:22])
+    if version != 1:
+        raise Exception(f"XAR version {version} not supported")
+    toc = fileobj.read(compressed_toc_len)
+    base = fileobj.tell()
+    if len(toc) != compressed_toc_len:
+        raise Exception("Failed to read XAR TOC")
+    toc = zlib.decompress(toc)
+    if len(toc) != uncompressed_toc_len:
+        raise Exception("Corrupted XAR?")
+    toc = XML(toc).find("toc")
+    for f in toc.findall("file"):
+        if f.find("type").text != "file":
+            continue
+        filename = f.find("name").text
+        data = f.find("data")
+        length = int(data.find("length").text)
+        size = int(data.find("size").text)
+        offset = int(data.find("offset").text)
+        encoding = data.find("encoding").get("style")
+        fileobj.seek(base + offset, os.SEEK_SET)
+        content = Take(fileobj, length)
+        if encoding == "application/octet-stream":
+            if length != size:
+                raise Exception(f"{length} != {size}")
+        elif encoding == "application/x-bzip2":
+            content = bz2.BZ2File(content)
+        else:
+            raise Exception(f"XAR encoding {encoding} not supported")
+
+        yield filename, content
 
 
 class Pbzx(object):