hooks: Improve the clang-format wrapper script

This change leverages upstream changes in git-clang-format to restrict
diffs to a single commit instead of diffing from a commit to whatever
is in the working tree. That mode of operation does not lend itself to
an easy invocation to automatically fix any violations (since it
requires the use of the --diff flag), so a --fix flag was also added to
the wrapper script in order to automatically apply any changes that are
needed to comply.

Bug: 31305183
Test: repo upload
Change-Id: I835f2e1923803ff8ac9aee451078e6c1c1dcc070

1 files changed, 39 insertions, 16 deletions

diff --git a/tools/clang-format.py b/tools/clang-format.py
index b4fbd31..ac9e826 100755
--- a/tools/clang-format.py
+++ b/tools/clang-format.py
@@ -43,23 +43,42 @@ def get_parser():
                         help='The path of the clang-format executable.')
     parser.add_argument('--git-clang-format', default='git-clang-format',
                         help='The path of the git-clang-format executable.')
-    parser.add_argument('--commit', type=str, default='HEAD',
-                        help='Specify the commit to validate.')
+    parser.add_argument('--style', metavar='STYLE', type=str,
+                        help='The style that clang-format will use.')
+    parser.add_argument('--extensions', metavar='EXTENSIONS', type=str,
+                        help='Comma-separated list of file extensions to '
+                             'format.')
+    parser.add_argument('--fix', action='store_true',
+                        help='Fix any formatting errors automatically.')
+
+    scope = parser.add_mutually_exclusive_group(required=True)
+    scope.add_argument('--commit', type=str, default='HEAD',
+                       help='Specify the commit to validate.')
+    scope.add_argument('--working-tree', action='store_true',
+                       help='Validates the files that have changed from '
+                            'HEAD in the working directory.')
+
+    parser.add_argument('files', type=str, nargs='*',
+                        help='If specified, only consider differences in '
+                             'these files.')
     return parser
 
 
 def main(argv):
     """The main entry."""
     parser = get_parser()
-    opts, unknown = parser.parse_known_args(argv)
-
-    # TODO(b/31305183): Avoid false positives by limiting git-clang-format's
-    # diffs to just that commit instead of from the parent of the commit against
-    # the working tree.
-    cmd = [opts.git_clang_format, '--binary',
-           opts.clang_format, '--commit=%s^' % opts.commit] + unknown
-
-    stdout = rh.utils.run_command(cmd + ['--diff'], capture_output=True).output
+    opts = parser.parse_args(argv)
+
+    cmd = [opts.git_clang_format, '--binary', opts.clang_format, '--diff']
+    if opts.style:
+        cmd.extend(['--style', opts.style])
+    if opts.extensions:
+        cmd.extend(['--extensions', opts.extensions])
+    if not opts.working_tree:
+        cmd.extend(['%s^' % opts.commit, opts.commit])
+    cmd.extend(['--'] + opts.files)
+
+    stdout = rh.utils.run_command(cmd, capture_output=True).output
     if stdout.rstrip('\n') == 'no modified files to format':
         # This is always printed when only files that clang-format does not
         # understand were modified.
@@ -71,11 +90,15 @@ def main(argv):
             diff_filenames.append(line[len(DIFF_MARKER_PREFIX):].rstrip())
 
     if diff_filenames:
-        print('The following files have formatting errors:')
-        for filename in diff_filenames:
-            print('\t%s' % filename)
-        print('You can run `%s` to fix this' % rh.shell.cmd_to_str(cmd))
-        return 1
+        if opts.fix:
+            rh.utils.run_command(['git', 'apply'], input=stdout)
+        else:
+            print('The following files have formatting errors:')
+            for filename in diff_filenames:
+                print('\t%s' % filename)
+            print('You can run `%s --fix %s` to fix this' %
+                  (sys.argv[0], rh.shell.cmd_to_str(argv)))
+            return 1
 
     return 0