git-acab

   1 #! /usr/bin/python3
   2 # amend HEAD commit to contain acab in its hash, it does so by repeatedly
   3 # amending the commit with a new date.
   4
   5 import argparse
   6 import hashlib
   7 import os
   8 import subprocess
   9 import sys
  10 import time
  11
  12 parser = argparse.ArgumentParser()
  13 parser.add_argument('--start', type=str, default='commit', help='now or commit')
  14 parser.add_argument('--prefix', action='store_true')
  15 parser.add_argument('--suffix', action='store_true')
  16 parser.add_argument('-q', '--quiet', action='store_true')
  17 args = parser.parse_args()
  18
  19
  20 def amend_commit(start_timestamp):
  21     t0 = time.time()
  22     counter = 0
  23     cat_file = subprocess.run(['git', 'cat-file', 'commit', 'HEAD'], capture_output=True).stdout
  24     cat_file_lines = cat_file.splitlines()
  25     cat_file_lines[2] = cat_file_lines[2].replace(cat_file_lines[2].rsplit(b' ', 2)[1], b'$AUTHOR__$')
  26     cat_file_lines[3] = cat_file_lines[3].replace(cat_file_lines[3].rsplit(b' ', 2)[1], b'$COMMITER$')
  27     hashed_bytes_template = b'commit %s\0%s\n' % (
  28         str(len(b'\n'.join(cat_file_lines)) + 1).encode(),
  29         b'\n'.join(cat_file_lines),
  30     )
  31     authored_timestamp = start_timestamp
  32     base_env = os.environ
  33     last_print = 0
  34     while True:
  35         authored_timestamp -= 1
  36         for committed_timestamp in range(start_timestamp, authored_timestamp, -1):
  37             counter += 1
  38             if not args.quiet and time.time() - last_print > 0.05:
  39                 last_print = time.time()
  40                 print(
  41                     '%5d - %s - %s - [%s:%02d]'
  42                     % (
  43                         counter,
  44                         time.strftime('%Y-%m-%d %H:%M:%S', time.localtime(authored_timestamp)),
  45                         time.strftime('%Y-%m-%d %H:%M:%S', time.localtime(committed_timestamp)),
  46                         int((time.time() - t0) // 60),
  47                         int((time.time() - t0) % 60),
  48                     ),
  49                     end='\r',
  50                 )
  51
  52             hashed_bytes = hashed_bytes_template.replace(
  53                 b'$AUTHOR__$', str(authored_timestamp).encode()
  54             ).replace(b'$COMMITER$', str(committed_timestamp).encode())
  55             new_hash = hashlib.sha1(hashed_bytes).hexdigest()
  56             if args.prefix and not new_hash.startswith('acab'):
  57                 continue
  58             if args.suffix and not new_hash.endswith('acab'):
  59                 continue
  60             if 'acab' not in new_hash:
  61                 continue
  62             base_env['GIT_COMMITTER_DATE'] = time.strftime(
  63                 '%Y-%m-%d %H:%M:%S', time.localtime(committed_timestamp)
  64             )
  65             subprocess.run(
  66                 [
  67                     'git',
  68                     'commit',
  69                     '--no-verify',
  70                     '--amend',
  71                     '--no-edit',
  72                     '--date=%s' % time.strftime('%Y-%m-%d %H:%M:%S', time.localtime(authored_timestamp)),
  73                 ],
  74                 capture_output=True,
  75                 env=base_env,
  76             )
  77             return
  78
  79
  80 if args.start == 'commit':
  81     p = subprocess.run(['git', 'show', '--format=format:%at'], capture_output=True)
  82     start_timestamp = int(p.stdout[: p.stdout.index(b'\n')])
  83 elif args.start == 'now':
  84     start_timestamp = int(time.time())
  85 else:
  86     sys.stderr('unknown value for --start')
  87     sys.exit(1)
  88
  89 amend_commit(start_timestamp)
  90
  91 if not args.quiet:
  92     p = subprocess.run(['git', 'rev-parse', 'HEAD'], capture_output=True)
  93     print('\ngot %s 🔥🚓' % p.stdout.decode().strip())