utils/CaptureCmd

   1 #!/usr/bin/env python
   2
   3 """CaptureCmd - A generic tool for capturing information about the
   4 invocations of another program.
   5
   6 Usage
   7 --
   8 1. Move the original tool to a safe known location.
   9
  10 2. Link CaptureCmd to the original tool's location.
  11
  12 3. Define CAPTURE_CMD_PROGRAM to the known location of the original
  13 tool; this must be an absolute path.
  14
  15 4. Define CAPTURE_CMD_DIR to a directory to write invocation
  16 information to.
  17 """
  18
  19 import hashlib
  20 import os
  21 import sys
  22 import time
  23
  24 def saveCaptureData(prefix, dir, object):
  25     string = repr(object) + '\n'
  26     key = hashlib.sha1(string).hexdigest()
  27     path = os.path.join(dir,
  28                         prefix + key)
  29     if not os.path.exists(path):
  30         f = open(path, 'wb')
  31         f.write(string)
  32         f.close()
  33     return prefix + key
  34
  35 def main():
  36     program = os.getenv('CAPTURE_CMD_PROGRAM')
  37     dir = os.getenv('CAPTURE_CMD_DIR')
  38     fallback = os.getenv('CAPTURE_CMD_FALLBACK')
  39     if not program:
  40         raise ValueError('CAPTURE_CMD_PROGRAM is not defined!')
  41     if not dir:
  42         raise ValueError('CAPTURE_CMD_DIR is not defined!')
  43
  44     # Make the output directory if it doesn't already exist.
  45     if not os.path.exists(dir):
  46         os.mkdir(dir, 0700)
  47
  48     # Get keys for various data.
  49     env = os.environ.items()
  50     env.sort()
  51     envKey = saveCaptureData('env-', dir, env)
  52     cwdKey = saveCaptureData('cwd-', dir, os.getcwd())
  53     argvKey = saveCaptureData('argv-', dir, sys.argv)
  54     entry = (time.time(), envKey, cwdKey, argvKey)
  55     saveCaptureData('cmd-', dir, entry)
  56
  57     if fallback:
  58         pid = os.fork()
  59         if not pid:
  60             os.execv(program, sys.argv)
  61             os._exit(1)
  62         else:
  63             res = os.waitpid(pid, 0)
  64             if not res:
  65                 os.execv(fallback, sys.argv)
  66                 os._exit(1)
  67             os._exit(res)
  68     else:
  69         os.execv(program, sys.argv)
  70         os._exit(1)
  71
  72 if __name__ == '__main__':
  73     main()