bin/chromite

#!/usr/bin/python
# Copyright (c) 2011 The Chromium OS Authors. All rights reserved.
# Use of this source code is governed by a BSD-style license that can be
# found in the LICENSE file.

"""Wrapper for the chromite shell.

This script is intended to run in several ways:
- Outside the chroot, it should be _copied_ to someplace that is in the
  path (like depot_tools).  It will search for the right chromite by looking
  for a file 'chromite/shell/main.py' upward based on the CWD.
- Inside the chroot, it might be _either_ copied to someplace in the path (since
  depot_tools is in the path in the chroot) or it might run from chromite/bin
  directly, which should be in the PATH.  In any case, we'll look for the
  real 'chromite/shell/main.py' based on the environment variable
  CROS_WORKON_SRCROOT, so it doesn't matter what the CWD is.

If you're looking at a copy and want to know where the original looks at, look
here:
  http://git.chromium.org/gitweb/?p=chromite.git;a=blob;f=bin/chromite

Since this script is _copied_, it should remain small and not use internal libs.

"""

# Python imports.
import os
import sys

def Search(path):
  """Return an iterator of lists of places to look for chromite."""

  if os.path.exists('/etc/debian_chroot'):
    # We're in the chroot.  Chromite should be in the python path inside the
    # chroot, so we don't do any searching.  NOTE that we purposely don't want
    # CROS_WORKON_SRCROOT in the python path.
    yield []
  else:
    # Look in $CROS_WORKON_SRCROOT first.  The idea is that a user would set
    # this manually if they wanted to specify a particular version of chromite.
    if 'CROS_WORKON_SRCROOT' in os.environ:
      yield [os.environ['CROS_WORKON_SRCROOT']]

    # Search upward until we either end up with a blank dir or the "parent" dir
    # doesn't change.
    prev_path = None
    while path and path != prev_path:
      yield [path]
      path, prev_path = os.path.dirname(path), path


for path in Search(os.getcwd()):
  sys.path = path + sys.path
  try:
    import chromite.shell.main
    break
  except ImportError, e:
    # Just in case there is actually something wrong with Chromite, print
    # a sensible error. We match only the end of the string so that we can
    # handle an error within the chromite directory.
    # The full error is 'No module named (chromite.)shell.main'
    # Note: If you hit the directory containing chromite on the way up, then
    # the error will be 'No module named shell.main' so we must check only the
    # shell.main part.
    if not str(e).endswith('shell.main'):
      raise

    # We've got different modules named chromite in the tree, pulling in the
    # wrong one will break the right one.  So unload it.
    if 'chromite' in sys.modules:
      del sys.modules['chromite']
    sys.path = sys.path[len(path):]
else:
  # TODO(dianders): Should we actually print out the 'repo init' call that
  # the user should use?
  sys.stderr.write(
      "ERROR: Couldn't find the chromite tool.\n"
      "\n"
      "Please change to a directory inside your Chromium OS source tree\n"
      "and retry.  If you need to setup a Chromium OS source tree, see:\n"
      "  http://www.chromium.org/chromium-os/developer-guide\n")
  sys.exit(1)

chromite.shell.main.main()