text: #!/usr/bin/python
  # Copyright 2015 The Chromium Authors. All rights reserved.
  # Use of this source code is governed by a BSD-style license that can be
  # found in the LICENSE file.
  
  """Utility for reading / writing command-line flag files on device(s)."""
  
  import argparse
  import sys
  
  import devil_chromium
  
  from devil.android import device_utils
  from devil.android import device_errors
  from devil.utils import cmd_helper
  
  
  def main():
    parser = argparse.ArgumentParser(description=__doc__)
    parser.usage = '''%(prog)s --device-path PATH [--device SERIAL] [flags...]
  
  No flags: Prints existing command-line file.
  Empty string: Deletes command-line file.
  Otherwise: Writes command-line file.
  
  '''
    parser.add_argument('-d', '--device', dest='device',
                        help='Target device for apk to install on.')
    parser.add_argument('--device-path', required=True,
                        help='Remote path to flags file.')
    args, remote_args = parser.parse_known_args()
  
    devil_chromium.Initialize()
  
    as_root = not args.device_path.startswith('/data/local/tmp/')
  
    if args.device:
      devices = [device_utils.DeviceUtils(args.device, default_retries=0)]
    else:
      devices = device_utils.DeviceUtils.HealthyDevices(default_retries=0)
      if not devices:
        raise device_errors.NoDevicesError()
  
    all_devices = device_utils.DeviceUtils.parallel(devices)
  
    def print_args():
      def read_flags(device):
        try:
          return device.ReadFile(args.device_path, as_root=as_root)
        except device_errors.AdbCommandFailedError:
          return '\n'  # File might not exist.
  
      descriptions = all_devices.pMap(lambda d: d.build_description).pGet(None)
      flags = all_devices.pMap(read_flags).pGet(None)
      for d, desc, flags in zip(devices, descriptions, flags):
        print '  %s (%s): %s' % (d, desc, flags),
  
    # No args == print flags.
    if not remote_args:
      print 'Existing flags (in %s):' % args.device_path
      print_args()
      return 0
  
    # Empty string arg == delete flags file.
    if len(remote_args) == 1 and not remote_args[0]:
      def delete_flags(device):
        device.RunShellCommand(['rm', '-f', args.device_path], as_root=as_root)
      all_devices.pMap(delete_flags).pGet(None)
      print 'Deleted %s' % args.device_path
      return 0
  
    # Set flags.
    quoted_args = ' '.join(cmd_helper.SingleQuote(x) for x in remote_args)
    flags_str = 'chrome %s' % quoted_args
  
    def write_flags(device):
      device.WriteFile(args.device_path, flags_str, as_root=as_root)
      device.RunShellCommand(['chmod', '0664', args.device_path], as_root=as_root)
  
    all_devices.pMap(write_flags).pGet(None)
    print 'Wrote flags to %s' % args.device_path
    print_args()
    return 0
  
  
  if __name__ == '__main__':
    sys.exit(main())
  