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      1 #!/usr/bin/python
      2 # Copyright (c) 2012 The Chromium Authors. All rights reserved.
      3 # Use of this source code is governed by a BSD-style license that can be
      4 # found in the LICENSE file.
      5 
      6 import os
      7 import sys
      8 
      9 def Main(argv):
     10   """This is like 'env -i', but it uses a whitelist of env variables to allow
     11   through to the command being run.  It attempts to strip off Xcode-added
     12   values from PATH.
     13   """
     14   # Note: An attempt was made to do something like: env -i bash -lc '[command]'
     15   # but that fails to set the things set by login (USER, etc.), so instead
     16   # the only approach that seems to work is to have a whitelist.
     17   env_key_whitelist = (
     18     'HOME',
     19     'LOGNAME',
     20     # 'PATH' added below (but filtered).
     21     'PWD',
     22     'SHELL',
     23     'TEMP',
     24     'TMPDIR',
     25     'USER'
     26   )
     27 
     28   # Need something to run.
     29   # TODO(lliabraa): Make this output a usage string and exit (here and below).
     30   assert(len(argv) > 0)
     31 
     32   add_to_path = [];
     33   first_entry = argv[0];
     34   if first_entry.startswith('ADD_TO_PATH='):
     35     argv = argv[1:];
     36     add_to_path = first_entry.replace('ADD_TO_PATH=', '', 1).split(':')
     37 
     38   # Still need something to run.
     39   assert(len(argv) > 0)
     40 
     41   clean_env = {}
     42 
     43   # Pull over the whitelisted keys.
     44   for key in env_key_whitelist:
     45     val = os.environ.get(key, None)
     46     if not val is None:
     47       clean_env[key] = val
     48 
     49   # Collect the developer dir as set via Xcode, defaulting it.
     50   dev_prefix = os.environ.get('DEVELOPER_DIR', '/Developer/')
     51   if dev_prefix[-1:] != '/':
     52     dev_prefix += '/'
     53 
     54   # Now pull in PATH, but remove anything Xcode might have added.
     55   initial_path = os.environ.get('PATH', '')
     56   filtered_chunks = \
     57       [x for x in initial_path.split(':') if not x.startswith(dev_prefix)]
     58   if filtered_chunks:
     59     clean_env['PATH'] = ':'.join(add_to_path + filtered_chunks)
     60 
     61   # Add any KEY=VALUE args before the command to the cleaned environment.
     62   args = argv[:]
     63   while '=' in args[0]:
     64     (key, val) = args[0].split('=', 1)
     65     clean_env[key] = val
     66     args = args[1:]
     67 
     68   # Still need something to run.
     69   assert(len(args) > 0)
     70 
     71   # Off it goes...
     72   os.execvpe(args[0], args, clean_env)
     73   # Should never get here, so return a distinctive, non-zero status code.
     74   return 66
     75 
     76 if __name__ == '__main__':
     77   sys.exit(Main(sys.argv[1:]))
     78