Allow CROS_WORKON_SRCROOT to be used outside the chroot.

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 ReportChromiteError(message):

[diandersAtChromium, 2011/02/01 23:08:16]

nit: Should probably start w/ _, since this is private.

+  print >>sys.stderr, (
+    "ERROR: Couldn't find the chromite tool.\n\n" + message +
+    "\n\nFor details and help, see:\n"
+    "  http://www.chromium.org/chromium-os/developer-guide"
+  )
+
+
+def TryChromiteShell(dir_, argv):

[diandersAtChromium, 2011/02/01 23:08:16]

nit: Also start w/ underscore.

+  chromite_path = os.path.join(dir_, 'chromite', 'shell', 'main.py')
+  if os.path.isfile(chromite_path):
+    env = os.environ.copy()
+    try:
+      import chromite
+    except:
+      if 'PYTHONPATH' in env:
+        env['PYTHONPATH'] += ':%s' % dir_
+      else:
+        env['PYTHONPATH'] = dir_
+    # Exec the script, which will never return.
+    os.execve(chromite_path, argv, env)
+
+
 if __name__ == '__main__':
-  # Look relative to CROS_WORKON_SRCROOT if that variable exists.  This is
-  # the "inside the chroot" case.
+  # Look relative to CROS_WORKON_SRCROOT if that variable exists.
+  # Inside the chroot, this variable should always be set; outside
+  # the setting is optional.
   if 'CROS_WORKON_SRCROOT' in os.environ:
-    chromite_path = os.path.join(os.environ['CROS_WORKON_SRCROOT'],
-                                 'chromite', 'shell', 'main.py')
-    if os.path.isfile(chromite_path):
-      # Exec the script, which will never return.
-      os.execv(chromite_path, sys.argv)
-    else:
-      print (
-          "ERROR: Couldn't find the chromite tool.\n"
-          "\n"
-          "You may need to update your chroot.  If you need help, see:\n"
-          "  http://www.chromium.org/chromium-os/developer-guide"
-      )
-      sys.exit(1)
+    TryChromiteShell(os.environ['CROS_WORKON_SRCROOT'], sys.argv)
+    ReportChromiteError(
+      "There is no chromite package in the path indicated by\n"
+      "CROS_WORKON_SRCROOT.  The variable may be set wrong, or you\n"
+      "may need to update your chroot.")
+    sys.exit(1)
 
-  # Outside the chroot, search upward until the "parent" dir doesn't change
-  # (on Linux, that means we're at '/').  That is an error case.
-  dir = os.getcwd()
+  # We're outside the chroot and CROS_WORKON_SRCROOT isn't set.
+  # Search upward until the parent dir doesn't change (on Linux,
+  # that means we're at '/').
+  dir_ = os.getcwd()
   prev_dir = None
-  while dir != prev_dir:
-    chromite_path = os.path.join(dir, 'chromite', 'shell', 'main.py')
-    if os.path.isfile(chromite_path):
-      # Add the directory above chromite to PYTHONPATH before executing, so
-      # that "import chromite.abc.xyz" works...
-      env = os.environ.copy()
-      if 'PYTHONPATH' in env:
-        env['PYTHONPATH'] += ':%s' % dir
-      else:
-        env['PYTHONPATH'] = dir
-
-      # Exec the script, which will never return.
-      os.execve(chromite_path, sys.argv, env)
-
-    prev_dir = dir
-    dir = os.path.dirname(dir)
-
-  # TODO(dianders): Should we actually print out the 'repo init' call that
-  # the user should use?
-  print (
-      "ERROR: Couldn't find the chromite tool.\n"
-      "\n"
+  while dir_ != prev_dir:
+    TryChromiteShell(dir_, sys.argv)
+    prev_dir = dir_
+    dir_ = os.path.dirname(dir_)
+  ReportChromiteError(
       "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"
-  )
+      "and retry.")
   sys.exit(1)