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Diffstat (limited to 'llvm_tools/revert_checker.py')
| -rwxr-xr-x | llvm_tools/revert_checker.py | 241 |
1 files changed, 0 insertions, 241 deletions
diff --git a/llvm_tools/revert_checker.py b/llvm_tools/revert_checker.py deleted file mode 100755 index bb9182b0..00000000 --- a/llvm_tools/revert_checker.py +++ /dev/null @@ -1,241 +0,0 @@ -#!/usr/bin/env python3 -# -*- coding: utf-8 -*- -# Copyright 2020 The Chromium OS Authors. All rights reserved. -# Use of this source code is governed by a BSD-style license that can be -# found in the LICENSE file. - -"""Checks for reverts of commits across a given git commit. - -To clarify the meaning of 'across' with an example, if we had the following -commit history (where `a -> b` notes that `b` is a direct child of `a`): - -123abc -> 223abc -> 323abc -> 423abc -> 523abc - -And where 423abc is a revert of 223abc, this revert is considered to be 'across' -323abc. More generally, a revert A of a parent commit B is considered to be -'across' a commit C if C is a parent of A and B is a parent of C. - -Please note that revert detection in general is really difficult, since merge -conflicts/etc always introduce _some_ amount of fuzziness. This script just -uses a bundle of heuristics, and is bound to ignore / incorrectly flag some -reverts. The hope is that it'll easily catch the vast majority (>90%) of them, -though. -""" - -# pylint: disable=cros-logging-import - -from __future__ import print_function - -import argparse -import collections -import logging -import re -import subprocess -import sys -import typing as t - -# People are creative with their reverts, and heuristics are a bit difficult. -# Like 90% of of reverts have "This reverts commit ${full_sha}". -# Some lack that entirely, while others have many of them specified in ad-hoc -# ways, while others use short SHAs and whatever. -# -# The 90% case is trivial to handle (and 100% free + automatic). The extra 10% -# starts involving human intervention, which is probably not worth it for now. - - -def _try_parse_reverts_from_commit_message(commit_message: str) -> t.List[str]: - if not commit_message: - return [] - - results = re.findall(r'This reverts commit ([a-f0-9]{40})\b', commit_message) - - first_line = commit_message.splitlines()[0] - initial_revert = re.match(r'Revert ([a-f0-9]{6,}) "', first_line) - if initial_revert: - results.append(initial_revert.group(1)) - return results - - -def _stream_stdout(command: t.List[str]) -> t.Generator[str, None, None]: - with subprocess.Popen( - command, stdout=subprocess.PIPE, encoding='utf-8', errors='replace') as p: - yield from p.stdout - - -def _resolve_sha(git_dir: str, sha: str) -> str: - if len(sha) == 40: - return sha - - return subprocess.check_output( - ['git', '-C', git_dir, 'rev-parse', sha], - encoding='utf-8', - stderr=subprocess.DEVNULL, - ).strip() - - -_LogEntry = t.NamedTuple('_LogEntry', [ - ('sha', str), - ('commit_message', t.List[str]), -]) - - -def _log_stream(git_dir: str, root_sha: str, - end_at_sha: str) -> t.Iterable[_LogEntry]: - sep = 50 * '<>' - log_command = [ - 'git', - '-C', - git_dir, - 'log', - '^' + end_at_sha, - root_sha, - '--format=' + sep + '%n%H%n%B%n', - ] - - stdout_stream = iter(_stream_stdout(log_command)) - - # Find the next separator line. If there's nothing to log, it may not exist. - # It might not be the first line if git feels complainy. - found_commit_header = False - for line in stdout_stream: - if line.rstrip() == sep: - found_commit_header = True - break - - while found_commit_header: - # crbug.com/1041148 - # pylint: disable=stop-iteration-return - sha = next(stdout_stream, None) - assert sha is not None, 'git died?' - sha = sha.rstrip() - - commit_message = [] - - found_commit_header = False - for line in stdout_stream: - line = line.rstrip() - if line.rstrip() == sep: - found_commit_header = True - break - commit_message.append(line) - - yield _LogEntry(sha, '\n'.join(commit_message).rstrip()) - - -def _shas_between(git_dir: str, base_ref: str, - head_ref: str) -> t.Iterable[str]: - rev_list = [ - 'git', - '-C', - git_dir, - 'rev-list', - '--first-parent', - '%s..%s' % (base_ref, head_ref), - ] - return (x.strip() for x in _stream_stdout(rev_list)) - - -def _rev_parse(git_dir: str, ref: str) -> str: - result = subprocess.check_output( - ['git', '-C', git_dir, 'rev-parse', ref], - encoding='utf-8', - ).strip() - return t.cast(str, result) - - -Revert = t.NamedTuple('Revert', [ - ('sha', str), - ('reverted_sha', str), -]) - - -def find_common_parent_commit(git_dir: str, ref_a: str, ref_b: str) -> str: - return subprocess.check_output( - ['git', '-C', git_dir, 'merge-base', ref_a, ref_b], - encoding='utf-8', - ).strip() - - -def find_reverts(git_dir: str, across_ref: str, root: str) -> t.List[Revert]: - """Finds reverts across `across_ref` in `git_dir`, starting from `root`.""" - across_sha = _rev_parse(git_dir, across_ref) - root_sha = _rev_parse(git_dir, root) - - common_ancestor = find_common_parent_commit(git_dir, across_sha, root_sha) - if common_ancestor != across_sha: - raise ValueError("%s isn't an ancestor of %s (common ancestor: %s)" % - (across_sha, root_sha, common_ancestor)) - - intermediate_commits = set(_shas_between(git_dir, across_sha, root_sha)) - assert across_ref not in intermediate_commits - - logging.debug('%d commits appear between %s and %s', - len(intermediate_commits), across_sha, root_sha) - - all_reverts = [] - for sha, commit_message in _log_stream(git_dir, root_sha, across_sha): - reverts = _try_parse_reverts_from_commit_message(commit_message) - if not reverts: - continue - - resolved_reverts = sorted(set(_resolve_sha(git_dir, x) for x in reverts)) - for reverted_sha in resolved_reverts: - if reverted_sha in intermediate_commits: - logging.debug('Commit %s reverts %s, which happened after %s', sha, - reverted_sha, across_sha) - continue - - try: - object_type = subprocess.check_output( - ['git', '-C', git_dir, 'cat-file', '-t', reverted_sha], - encoding='utf-8', - stderr=subprocess.DEVNULL, - ).strip() - except subprocess.CalledProcessError: - logging.warning( - 'Failed to resolve reverted object %s (claimed to be reverted ' - 'by sha %s)', reverted_sha, sha) - continue - - if object_type == 'commit': - all_reverts.append(Revert(sha, reverted_sha)) - continue - - logging.error("%s claims to revert %s -- which isn't a commit -- %s", sha, - object_type, reverted_sha) - - return all_reverts - - -def main(args: t.List[str]) -> int: - parser = argparse.ArgumentParser( - description=__doc__, formatter_class=argparse.RawDescriptionHelpFormatter) - parser.add_argument( - 'base_ref', help='Git ref or sha to check for reverts around.') - parser.add_argument( - '-C', '--git_dir', default='.', help='Git directory to use.') - parser.add_argument( - 'root', nargs='+', help='Root(s) to search for commits from.') - parser.add_argument('--debug', action='store_true') - opts = parser.parse_args(args) - - logging.basicConfig( - format='%(asctime)s: %(levelname)s: %(filename)s:%(lineno)d: %(message)s', - level=logging.DEBUG if opts.debug else logging.INFO, - ) - - # `root`s can have related history, so we want to filter duplicate commits - # out. The overwhelmingly common case is also to have one root, and it's way - # easier to reason about output that comes in an order that's meaningful to - # git. - all_reverts = collections.OrderedDict() - for root in opts.root: - for revert in find_reverts(opts.git_dir, opts.base_ref, root): - all_reverts[revert] = None - - for revert in all_reverts.keys(): - print('%s claims to revert %s' % (revert.sha, revert.reverted_sha)) - - -if __name__ == '__main__': - sys.exit(main(sys.argv[1:])) |