michael@0: #!/usr/bin/python
michael@0: # Copyright (c) 2012 The Chromium Authors. All rights reserved.
michael@0: # Use of this source code is governed by a BSD-style license that can be
michael@0: # found in the LICENSE file.
michael@0: 
michael@0: import os
michael@0: import sys
michael@0: 
michael@0: def Main(argv):
michael@0:   """This is like 'env -i', but it uses a whitelist of env variables to allow
michael@0:   through to the command being run.  It attempts to strip off Xcode-added
michael@0:   values from PATH.
michael@0:   """
michael@0:   # Note: An attempt was made to do something like: env -i bash -lc '[command]'
michael@0:   # but that fails to set the things set by login (USER, etc.), so instead
michael@0:   # the only approach that seems to work is to have a whitelist.
michael@0:   env_key_whitelist = (
michael@0:     'HOME',
michael@0:     'LOGNAME',
michael@0:     # 'PATH' added below (but filtered).
michael@0:     'PWD',
michael@0:     'SHELL',
michael@0:     'TEMP',
michael@0:     'TMPDIR',
michael@0:     'USER'
michael@0:   )
michael@0: 
michael@0:   # Need something to run.
michael@0:   # TODO(lliabraa): Make this output a usage string and exit (here and below).
michael@0:   assert(len(argv) > 0)
michael@0: 
michael@0:   add_to_path = [];
michael@0:   first_entry = argv[0];
michael@0:   if first_entry.startswith('ADD_TO_PATH='):
michael@0:     argv = argv[1:];
michael@0:     add_to_path = first_entry.replace('ADD_TO_PATH=', '', 1).split(':')
michael@0: 
michael@0:   # Still need something to run.
michael@0:   assert(len(argv) > 0)
michael@0: 
michael@0:   clean_env = {}
michael@0: 
michael@0:   # Pull over the whitelisted keys.
michael@0:   for key in env_key_whitelist:
michael@0:     val = os.environ.get(key, None)
michael@0:     if not val is None:
michael@0:       clean_env[key] = val
michael@0: 
michael@0:   # Collect the developer dir as set via Xcode, defaulting it.
michael@0:   dev_prefix = os.environ.get('DEVELOPER_DIR', '/Developer/')
michael@0:   if dev_prefix[-1:] != '/':
michael@0:     dev_prefix += '/'
michael@0: 
michael@0:   # Now pull in PATH, but remove anything Xcode might have added.
michael@0:   initial_path = os.environ.get('PATH', '')
michael@0:   filtered_chunks = \
michael@0:       [x for x in initial_path.split(':') if not x.startswith(dev_prefix)]
michael@0:   if filtered_chunks:
michael@0:     clean_env['PATH'] = ':'.join(add_to_path + filtered_chunks)
michael@0: 
michael@0:   # Add any KEY=VALUE args before the command to the cleaned environment.
michael@0:   args = argv[:]
michael@0:   while '=' in args[0]:
michael@0:     (key, val) = args[0].split('=', 1)
michael@0:     clean_env[key] = val
michael@0:     args = args[1:]
michael@0: 
michael@0:   # Still need something to run.
michael@0:   assert(len(args) > 0)
michael@0: 
michael@0:   # Off it goes...
michael@0:   os.execvpe(args[0], args, clean_env)
michael@0:   # Should never get here, so return a distinctive, non-zero status code.
michael@0:   return 66
michael@0: 
michael@0: if __name__ == '__main__':
michael@0:   sys.exit(Main(sys.argv[1:]))