Accept Git trailer Build-Id

… in place of Piper tag BUILD_NUMBER, to avoid corrupting Git trailers.

Issue: 296119824
Reviewed-on: #2013
(cherry picked from commit 0e24f1d)

cobalt/build/build_info.py

@@ -0,0 +1,132 @@
+#!/usr/bin/env python
+# Copyright 2023 The Cobalt Authors. All Rights Reserved.
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+#     http://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Generates a Cobalt Build Info json."""
+
+import datetime
+import json
+import os
+import re
+import subprocess
+import sys
+
+FILE_DIR = os.path.dirname(__file__)
+COMMIT_COUNT_BUILD_ID_OFFSET = 1000000
+
+_BUILD_ID_PATTERN = '^(Build-Id: |BUILD_NUMBER=)([1-9][0-9]{6,})$'
+_GIT_REV_PATTERN = '^GitOrigin-RevId: ([0-9a-f]{40})$'
+_COBALT_VERSION_PATTERN = '^#define COBALT_VERSION "(.*)"$'
+
+
+def get_build_id_and_git_rev_from_commits(cwd):
+  # Build id and git rev must come from the same commit.
+  output = subprocess.check_output(
+      ['git', 'log', '--grep', _BUILD_ID_PATTERN, '-1', '-E', '--pretty=%b'],
+      cwd=cwd).decode()
+
+  # Gets build id.
+  compiled_build_id_pattern = re.compile(_BUILD_ID_PATTERN, flags=re.MULTILINE)
+  match_build_id = compiled_build_id_pattern.search(output)
+  if not match_build_id:
+    return None, None
+  build_id = match_build_id.group(2)
+
+  # Gets git rev.
+  compiled_git_rev_pattern = re.compile(_GIT_REV_PATTERN, flags=re.MULTILINE)
+  match_git_rev = compiled_git_rev_pattern.search(output)
+  if not match_git_rev:
+    git_rev = ''
+  else:
+    git_rev = match_git_rev.group(1)
+
+  return build_id, git_rev
+
+
+def get_build_id_from_commit_count(cwd):
+  output = subprocess.check_output(['git', 'rev-list', '--count', 'HEAD'],
+                                   cwd=cwd)
+  build_id = int(output.strip().decode()) + COMMIT_COUNT_BUILD_ID_OFFSET
+  return str(build_id)
+
+
+def _get_last_commit_with_format(placeholder, cwd):
+  output = subprocess.check_output(
+      ['git', 'log', '-1', f'--pretty=format:{placeholder}'], cwd=cwd)
+  return output.strip().decode()
+
+
+def _get_hash_from_last_commit(cwd):
+  return _get_last_commit_with_format(r'%H', cwd=cwd)
+
+
+def _get_author_from_last_commit(cwd):
+  return _get_last_commit_with_format(r'%an', cwd=cwd)
+
+
+def _get_subject_from_last_commit(cwd):
+  return _get_last_commit_with_format(r'%s', cwd=cwd)
+
+
+def _get_cobalt_version():
+  version_header_path = os.path.join(os.path.dirname(FILE_DIR), 'version.h')
+  contents = ''
+  with open(version_header_path, 'r', encoding='utf-8') as f:
+    contents = f.read()
+  compiled_cobalt_version_pattern = re.compile(
+      _COBALT_VERSION_PATTERN, flags=re.MULTILINE)
+  return compiled_cobalt_version_pattern.search(contents).group(1)
+
+
+def main(output_path, cwd=FILE_DIR):
+  """Writes a Cobalt build_info json file."""
+  build_rev = _get_hash_from_last_commit(cwd=cwd)
+  build_id, git_rev = get_build_id_and_git_rev_from_commits(cwd=cwd)
+  if build_id is None:
+    build_id = get_build_id_from_commit_count(cwd=cwd)
+    git_rev = build_rev
+  cobalt_version = _get_cobalt_version()
+  build_time = datetime.datetime.now().ctime()
+  author = _get_author_from_last_commit(cwd=cwd)
+  commit = _get_subject_from_last_commit(cwd=cwd)
+
+  info_json = {
+      'build_id': build_id,
+      'build_rev': build_rev,
+      'git_rev': git_rev,
+      'cobalt_version': cobalt_version,
+      'build_time': build_time,
+      'author': author,
+      'commit': commit
+  }
+
+  with open(output_path, 'w', encoding='utf-8') as f:
+    f.write(json.dumps(info_json, indent=4))
+
+  # Supports legacy build_info.txt.
+  output_text_path = os.path.join(
+      os.path.dirname(output_path), 'build_info.txt')
+  with open(output_text_path, 'w', encoding='utf-8') as f:
+    f.write(f'''\
+Build ID: {build_id}
+Build Rev: {build_rev}
+Git Rev: {git_rev}
+Cobalt Version: {cobalt_version}
+Build Time: {build_time}
+Author: {author}
+Commit: {commit}
+''')
+
+
+if __name__ == '__main__':
+  main(sys.argv[1])