pak_util.py: Make decompress files when extracting

Useful when trying to inspect pak files now that many entries are
compressed.

Bug: 1271380
Change-Id: I83bb25f3d87b02686fa72deca01cb2c9ec92429c
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/3295870
Auto-Submit: Andrew Grieve <agrieve@chromium.org>
Reviewed-by: Dirk Pranke <dpranke@google.com>
Reviewed-by: Peter Wen <wnwen@chromium.org>
Commit-Queue: Andrew Grieve <agrieve@chromium.org>
Cr-Commit-Position: refs/heads/main@{#944705}

testing/scripts/run_isolated_script_test.py

@@ -47,11 +47,13 @@
     'run_blinkpy_tests.py',
     'run_mac_signing_tests.py',
     'run_mini_installer_tests.py',
+    'test_suite_all.py',  # //tools/grit:grit_python_unittests
 }
 
 KNOWN_TYP_VPYTHON3_TEST_RUNNERS = {
     'monochrome_python_tests.py',
     'run_polymer_tools_tests.py',
+    'test_suite_all.py',  # //tools/grit:grit_python_unittests
 }
 
 class IsolatedScriptTestAdapter(common.BaseIsolatedScriptArgsAdapter):

tools/grit/pak_util.py

@@ -16,6 +16,7 @@
 import hashlib
 import os
 import shutil
+import subprocess
 import sys
 import tempfile
 
@@ -25,8 +26,11 @@
 
 import six
 
+from grit import constants
 from grit.format import data_pack
 
+_GZIP_HEADER = b'\x1f\x8b'
+
 
 def _RepackMain(args):
   output_info_filepath = args.output_pak_file + '.info'
@@ -52,6 +56,26 @@ def _RepackMain(args):
         shutil.copyfileobj(temp_outfile, outgz)
 
 
+def _MaybeDecompress(payload, brotli_path=None):
+  if payload.startswith(_GZIP_HEADER):
+    return gzip.decompress(payload)
+  if payload.startswith(constants.BROTLI_CONST):
+    shell = brotli_path is None
+    brotli_path = brotli_path or 'brotli'
+    # Size is 6 bytes. We don't need it, so skip it.
+    try:
+      result = subprocess.run([brotli_path, '--decompress', '--stdout'],
+                              shell=shell,
+                              input=payload[8:],
+                              stdout=subprocess.PIPE,
+                              check=True)
+    except subprocess.CalledProcessError as e:
+      sys.stderr.write(str(e) + '\n')
+      sys.exit(1)
+    return result.stdout
+  return payload
+
+
 def _ExtractMain(args):
   pak = data_pack.ReadDataPack(args.pak_file)
   if args.textual_id:
@@ -62,6 +86,8 @@ def _ExtractMain(args):
         if args.textual_id else str(resource_id))
     path = os.path.join(args.output_dir, filename)
     with open(path, 'wb') as f:
+      if not args.raw:
+        payload = _MaybeDecompress(payload, args.brotli)
       f.write(payload)
 
 
@@ -174,6 +200,13 @@ def main():
   sub_parser.add_argument('pak_file')
   sub_parser.add_argument('-o', '--output-dir', default='.',
                           help='Directory to extract to.')
+  sub_parser.add_argument('--raw',
+                          action='store_true',
+                          help='Do not decompress when extracting.')
+  sub_parser.add_argument('--brotli',
+                          help='Path to brotli executable. Needed only to '
+                          'decompress brotli-compressed entries. For a '
+                          'chromium checkout, find in your output directory')
   sub_parser.add_argument(
       '-t',
       '--textual-id',