android: Handle no-init_array libraries in assert_static_initializers.py.

The chromium linker doesn't have static initializers, which make
assert_static_initializers.py fail. Instead of adding it to the list of
libraries that should be skipped, make sure that it has none.

Bug: 979638
Change-Id: I5450031a2e49dbfbf21d991ac6b901ddbb5c7008
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1760215Reviewed-by: Sam Maier <smaier@chromium.org>
Commit-Queue: Benoit L <lizeb@chromium.org>
Cr-Commit-Position: refs/heads/master@{#688077}

build/android/gyp/assert_static_initializers.py

@@ -60,17 +60,23 @@ def _PrintDumpSIsCount(apk_so_name, unzipped_so, out_dir, tool_prefix):
 
 
 # Mostly copied from //infra/scripts/legacy/scripts/slave/chromium/sizes.py.
-def _ReadInitArray(so_path, tool_prefix):
+def _ReadInitArray(so_path, tool_prefix, expect_no_initializers):
   stdout = _RunReadelf(so_path, ['-SW'], tool_prefix)
-  # Matches: .ctors PROGBITS 000000000516add0 5169dd0 000010 00 WA 0 0 8
+  # Matches: .init_array INIT_ARRAY 000000000516add0 5169dd0 000010 00 WA 0 0 8
   match = re.search(r'\.init_array.*$', stdout, re.MULTILINE)
-  if not match:
+  if expect_no_initializers:
+    if match:
+      raise Exception(
+          'Expected no initializers for %s, yet some were found' % so_path)
+    else:
+      return 0
+  elif not match:
     raise Exception('Did not find section: .init_array in:\n' + stdout)
   size_str = re.split(r'\W+', match.group(0))[5]
   return int(size_str, 16)
 
 
-def _CountStaticInitializers(so_path, tool_prefix):
+def _CountStaticInitializers(so_path, tool_prefix, expect_no_initializers):
   # Find the number of files with at least one static initializer.
   # First determine if we're 32 or 64 bit
   stdout = _RunReadelf(so_path, ['-h'], tool_prefix)
@@ -84,12 +90,12 @@ def _CountStaticInitializers(so_path, tool_prefix):
   # Then find the number of files with global static initializers.
   # NOTE: this is very implementation-specific and makes assumptions
   # about how compiler and linker implement global static initializers.
-  init_array_size = _ReadInitArray(so_path, tool_prefix)
+  init_array_size = _ReadInitArray(so_path, tool_prefix, expect_no_initializers)
   return init_array_size / word_size
 
 
 def _AnalyzeStaticInitializers(apk_filename, tool_prefix, dump_sis, out_dir,
-                               ignored_libs):
+                               ignored_libs, no_initializers_libs):
   # Static initializer counting mostly copies logic in
   # infra/scripts/legacy/scripts/slave/chromium/sizes.py.
   with zipfile.ZipFile(apk_filename) as z:
@@ -105,10 +111,13 @@ def _AnalyzeStaticInitializers(apk_filename, tool_prefix, dump_sis, out_dir,
 
     si_count = 0
     for f in files_to_check:
+      expect_no_initializers = (os.path.basename(
+          f.filename) in no_initializers_libs)
       with tempfile.NamedTemporaryFile() as temp:
         temp.write(z.read(f))
         temp.flush()
-        si_count += _CountStaticInitializers(temp.name, tool_prefix)
+        si_count += _CountStaticInitializers(temp.name, tool_prefix,
+                                             expect_no_initializers)
         if dump_sis:
           # Print count and list of SIs reported by dump-static-initializers.py.
           # Doesn't work well on all archs (particularly arm), which is why
@@ -128,11 +137,14 @@ def main():
   parser.add_argument('apk', help='APK file path.')
   args = parser.parse_args()
 
-  #TODO(crbug.com/838414): add support for files included via loadable_modules.
+  # TODO(crbug.com/838414): add support for files included via loadable_modules.
   ignored_libs = ['libarcore_sdk_c.so']
+  # The chromium linker doesn't have static initializers, which makes the
+  # regular check throw. It should not have any.
+  no_initializers_libs = ['libchromium_android_linker.so']
 
   si_count = _AnalyzeStaticInitializers(args.apk, args.tool_prefix, False, '.',
-                                        ignored_libs)
+                                        ignored_libs, no_initializers_libs)
   if si_count != args.expected_count:
     print('Expected {} static initializers, but found {}.'.format(
         args.expected_count, si_count))
@@ -144,7 +156,7 @@ def main():
       print('Dumping static initializers via dump-static-initializers.py:')
       sys.stdout.flush()
       _AnalyzeStaticInitializers(args.apk, args.tool_prefix, True, '.',
-                                 ignored_libs)
+                                 ignored_libs, no_initializers_libs)
       print()
       print('If the above list is not useful, consider listing them with:')
       print('    //tools/binary_size/diagnose_bloat.py')