WIP Chromite supporting "LEGACY" mode, as requested by Anush.

chromite/chromite.py

Index: chromite/chromite.py
diff --git a/chromite/chromite.py b/chromite/chromite.py
new file mode 100755
index 0000000000000000000000000000000000000000..ba80f9f33edd5471eb5f7862ed2d5442e9b8a083
--- /dev/null
+++ b/chromite/chromite.py
@@ -0,0 +1,1064 @@
+#!/usr/bin/python
+# Copyright (c) 2010 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.
+
+"""Chromite."""
+
+# Python imports
+import ConfigParser
+import cPickle
+import optparse
+import os
+import sys
+import tempfile
+
+
+# Local library imports
+from lib import text_menu
+from lib.cros_build_lib import Die
+from lib.cros_build_lib import Info
+from lib.cros_build_lib import IsInsideChroot
+from lib.cros_build_lib import RunCommand
+from lib.cros_build_lib import Warning as Warn
+
+
+# Find the Chromium OS root and Chromite root...
+_CHROMITE_PATH = os.path.dirname(os.path.realpath(__file__))
+_SRCROOT_PATH = os.path.realpath(os.path.join(_CHROMITE_PATH, '..', '..', '..'))
+
+
+# Commands can take one of these two types of specs.  Note that if a command
+# takes a build spec, we will find the associated chroot spec.  This should be
+# a human-readable string.  It is printed and also is the name of the spec
+# directory.
+_BUILD_SPEC_TYPE = 'build'
+_CHROOT_SPEC_TYPE = 'chroot'
+
+
+# This is a special target that indicates that you want to do something just
+# to the host.  This means different things to different commands.
+# TODO(dianders): Good idea or bad idea?
+_HOST_TARGET = 'HOST'
+
+
+# Define command handlers and command strings.  We define them in this way
+# so that someone searching for what calls _CmdXyz can find it easy with a grep.
+#
+# ORDER MATTERS here when we show the menu.
+#
+# TODO(dianders): Make a command superclass, then make these subclasses.
+_COMMAND_HANDLERS = [
+    '_CmdBuild',
+    '_CmdClean',
+    '_CmdEbuild',
+    '_CmdEmerge',
+    '_CmdEquery',
+    '_CmdPortageq',
+    '_CmdShell',
+    '_CmdWorkon',
+]
+_COMMAND_STRS = [fn_str[len('_Cmd'):].lower() for fn_str in _COMMAND_HANDLERS]
+
+
+def _GetBoardDir(build_config):
+  """Returns the board directory (inside the chroot) given the name.
+
+  Args:
+    build_config: A SafeConfigParser representing the config that we're
+        building.
+
+  Returns:
+    The absolute path to the board.
+  """
+  target_name = build_config.get('BUILD', 'target')
+
+  # Extra checks on these, since we sometimes might do a rm -f on the board
+  # directory and these could cause some really bad behavior.
+  assert target_name, "Didn't expect blank target name."
+  assert len(target_name.split()) == 1, 'Target name should have no whitespace.'
+
+  return os.path.join('/', 'build', target_name)
+
+
+def _GetChrootAbsDir(chroot_config):
+  """Returns the absolute chroot directory the chroot config.
+
+  Args:
+    chroot_config: A SafeConfigParser representing the config for the chroot.
+
+  Returns:
+    The chroot directory, always absolute.
+  """
+  chroot_dir = chroot_config.get('CHROOT', 'path')
+  chroot_dir = os.path.join(_SRCROOT_PATH, chroot_dir)
+
+  return chroot_dir
+
+
+def _DoesChrootExist(chroot_config):
+  """Return True if the chroot folder exists.
+
+  Args:
+    chroot_config: A SafeConfigParser representing the config for the chroot.
+
+  Returns:
+    True if the chroot folder exists.
+  """
+  chroot_dir = _GetChrootAbsDir(chroot_config)
+  return os.path.isdir(chroot_dir)
+
+
+def _FindCommand(cmd_name):
+  """Find the command that matches the given command name.
+
+  This tries to be smart.  See the cmd_name parameter for details.
+
+  Args:
+    cmd_name: Can be any of the following:
+        1. The full name of a command.  This is checked first so that if one
+           command name is a substring of another, you can still specify
+           the shorter spec name and know you won't get a menu (the exact
+           match prevents the menu).
+        2. A _prefix_ that will be used to pare-down a menu of commands
+           Can be the empty string to show a menu of all commands
+
+  Returns:
+    The command name.
+  """
+  # Always make cmd_name lower.  Commands are case-insensitive.
+  cmd_name = cmd_name.lower()
+
+  # If we're an exact match, we're done!
+  if cmd_name in _COMMAND_STRS:
+    return cmd_name
+
+  # Find ones that match and put them in a menu...
+  possible_cmds = []
+  possible_choices = []
+  for cmd_num, this_cmd in enumerate(_COMMAND_STRS):
+    if this_cmd.startswith(cmd_name):
+      handler = eval(_COMMAND_HANDLERS[cmd_num])
+      assert hasattr(handler, '__doc__'), \
+             ('All handlers must have docstrings: %s' % cmd_name)
+      desc = handler.__doc__.splitlines()[0]
+
+      possible_cmds.append(this_cmd)
+      possible_choices.append('%s - %s' % (this_cmd, desc))
+
+  if not possible_choices:
+    Die('No commands matched: "%s".  '
+        'Try running with no arguments for a menu.' %
+        cmd_name)
+
+  if cmd_name and len(possible_choices) == 1:
+    # Avoid showing the user a menu if the user's search string matched exactly
+    # one item.
+    choice = 0
+    Info("Running command '%s'." % possible_cmds[choice])
+  else:
+    choice = text_menu.TextMenu(possible_choices, 'Which chromite command',
+                                menu_width=0)
+
+  if choice is None:
+    Die('OK, cancelling...')
+  else:
+    return possible_cmds[choice]
+
+
+def _FindSpec(spec_name, spec_type=_BUILD_SPEC_TYPE, can_show_ui=True):
+  """Find the spec with the given name.
+
+  This tries to be smart about helping the user to find the right spec.  See
+  the spec_name parameter for details.
+
+  Args:
+    spec_name: Can be any of the following:
+        1. A full path to a spec file (including the .spec suffix).  This is
+           checked first (i.e. if os.path.isfile(spec_name), we assume we've
+           got this case).
+        2. The full name of a spec file somewhere in the spec search path
+           (not including the .spec suffix).  This is checked second.  Putting
+           this check second means that if one spec name is a substring of
+           another, you can still specify the shorter spec name and know you
+           won't get a menu (the exact match prevents the menu).
+        3. A substring that will be used to pare-down a menu of spec files
+           found in the spec search path.  Can be the empty string to show a
+           menu of all spec files in the spec path.  NOTE: Only possible if
+           can_show_ui is True.
+    spec_type: The type of spec this is: 'chroot' or 'build'.
+    can_show_ui: If True, enables the spec name to be a substring since we can
+        then show a menu if the substring matches more than one thing.
+
+  Returns:
+    A path to the spec file.
+  """
+  spec_suffix = '.spec'
+
+  # Handle 'HOST' for spec name w/ no searching, so it counts as an exact match.
+  if spec_type == _BUILD_SPEC_TYPE and spec_name == _HOST_TARGET.lower():
+    return _HOST_TARGET
+
+  # If we have an exact path name, that's it.  No searching.
+  if os.path.isfile(spec_name):
+    return spec_name
+
+  # Figure out what our search path should be.
+  # ...make these lists in anticipation of the need to support specs that live
+  # in private overlays.
+  search_path = [
+      os.path.join(_CHROMITE_PATH, 'specs', spec_type),
+  ]
+
+  # Look for an exact match of a spec name.  An exact match will go through with
+  # no menu.
+  if spec_name:
+    for dir_path in search_path:
+      spec_path = os.path.join(dir_path, spec_name + spec_suffix)
+      if os.path.isfile(spec_path):
+        return spec_path
+
+  # Die right away if we can't show UI and didn't have an exact match.
+  if not can_show_ui:
+    Die("Couldn't find %s spec: %s" % (spec_type, spec_name))
+
+  # No full path and no exact match.  Move onto a menu.
+  # First step is to construct the options.  We'll store in a dict keyed by
+  # spec name.
+  options = {}
+  for dir_path in search_path:
+    for file_name in os.listdir(dir_path):
+      # Find any files that end with ".spec" in a case-insensitive manner.
+      if not file_name.lower().endswith(spec_suffix):
+        continue
+
+      this_spec_name, _ = os.path.splitext(file_name)
+
+      # Skip if this spec file doesn't contain our substring.  We are _always_
+      # case insensitive here to be helpful to the user.
+      if spec_name.lower() not in this_spec_name.lower():
+        continue
+
+      # Disallow the spec to appear twice in the search path.  This is the
+      # safest thing for now.  We could revisit it later if we ever found a
+      # good reason (and if we ever have more than one directory in the
+      # search path).
+      if this_spec_name in options:
+        Die('Spec %s was found in two places in the search path' %
+            this_spec_name)
+
+      # Combine to get a full path.
+      full_path = os.path.join(dir_path, file_name)
+
+      # Ignore directories or anything else that isn't a file.
+      if not os.path.isfile(full_path):
+        continue
+
+      # OK, it's good.  Store the path.
+      options[this_spec_name] = full_path
+
+  # Add 'HOST'.  All caps so it sorts first.
+  if (spec_type == _BUILD_SPEC_TYPE and
+      spec_name.lower() in _HOST_TARGET.lower()):
+    options[_HOST_TARGET] = _HOST_TARGET
+
+  # If no match, die.
+  if not options:
+    Die("Couldn't find any matching %s specs for: %s" % (spec_type, spec_name))
+
+  # Avoid showing the user a menu if the user's search string matched exactly
+  # one item.
+  if spec_name and len(options) == 1:
+    _, spec_path = options.popitem()
+    return spec_path
+
+  # If more than one, show a menu...
+  option_keys = sorted(options.iterkeys())
+  choice = text_menu.TextMenu(option_keys, 'Choose a %s spec' % spec_type)
+
+  if choice is None:
+    Die('OK, cancelling...')
+  else:
+    return options[option_keys[choice]]
+
+
+def _ReadConfig(spec_path):
+  """Read the a build config or chroot config from a spec file.
+
+  This includes adding thue proper _default stuff in.
+
+  Args:
+    spec_path: The path to the build or chroot spec.
+
+  Returns:
+    config: A SafeConfigParser representing the config.
+  """
+  spec_name, _ = os.path.splitext(os.path.basename(spec_path))
+  spec_dir = os.path.dirname(spec_path)
+
+  config = ConfigParser.SafeConfigParser({'name': spec_name})
+  config.read(os.path.join(spec_dir, '_defaults'))
+  config.read(spec_path)
+
+  return config
+
+
+def _GetBuildConfigFromArgs(argv):
+  """Helper for commands that take a build config in the arg list.
+
+  This function can Die() in some instances.
+
+  Args:
+    argv: A list of command line arguments.  If non-empty, [0] should be the
+        build spec.  These will not be modified.
+
+  Returns:
+    argv: The argv with the build spec stripped off.  This might be argv[1:] or
+        just argv.  Not guaranteed to be new memory.
+    build_config: The SafeConfigParser for the build config; might be None if
+        this is a host config.  TODO(dianders): Should there be a build spec for
+        the host?
+  """
+  # The spec name is optional.  If no arguments, we'll show a menu...
+  # Note that if there are arguments, but the first argument is a flag, we'll
+  # assume that we got called before OptionParser.  In that case, they might
+  # have specified options but still want the board menu.
+  if argv and not argv[0].startswith('-'):
+    spec_name = argv[0]
+    argv = argv[1:]
+  else:
+    spec_name = ''
+
+  spec_path = _FindSpec(spec_name)
+
+  if spec_path == _HOST_TARGET:
+    return argv, None
+
+  build_config = _ReadConfig(spec_path)
+
+  # TODO(dianders): Add a config checker class that makes sure that the
+  # target is not a blank string.  Might also be good to make sure that the
+  # target has no whitespace (so we don't screw up a subcommand invoked
+  # through a shell).
+
+  return argv, build_config
+
+
+def _SplitEnvFromArgs(argv):
+  """Split environment settings from arguments.
+
+  This function will just loop over the arguments, looking for ones with an '='
+  character in them.  As long as it finds them, it takes them out of the arg
+  list adds them to a dictionary.  As soon as it finds the first argument
+  without an '=', it stops looping.
+
+  NOTE: Some doctests below test for equality with ==, since dicts with more
+        than one item may be arbitrarily ordered.
+
+  >>> result = _SplitEnvFromArgs(['abc=1', 'def=two', 'three'])
+  >>> result == ({'abc': '1', 'def': 'two'}, ['three'])
+  True
+
+  >>> _SplitEnvFromArgs(['one', 'two', 'three'])
+  ({}, ['one', 'two', 'three'])
+
+  >>> _SplitEnvFromArgs(['abc=1', 'three', 'def=two'])
+  ({'abc': '1'}, ['three', 'def=two'])
+
+  >>> result = _SplitEnvFromArgs(['abc=1', 'ghi=4 4', 'def=two'])
+  >>> result == ({'abc': '1', 'ghi': '4 4', 'def': 'two'}, [])
+  True
+
+  >>> _SplitEnvFromArgs(['abc=1', 'abc=2', 'three'])
+  ({'abc': '2'}, ['three'])
+
+  >>> _SplitEnvFromArgs([])
+  ({}, [])
+
+  Args:
+    argv: The arguments to parse; this list is not modified.  Should
+        not include "argv[0]"
+  Returns:
+    env: A dict containing key=value paris.
+    argv: A new list containing anything left after.
+  """
+  # Copy the list so we don't screw with caller...
+  argv = list(argv)
+
+  env = {}
+  while argv:
+    if '=' in argv[0]:
+      key, val = argv.pop(0).split('=', 2)
+      env[key] = val
+    else:
+      break
+
+  return env, argv
+
+
+def _DoMakeChroot(chroot_config, clean_first):
+  """Build the chroot, if needed.
+
+  Args:
+    chroot_config: A SafeConfigParser representing the config for the chroot.
+    clean_first: Delete any old chroot first.
+  """
+  # Skip this whole command if things already exist.
+  # TODO(dianders): Theoretically, calling make_chroot a second time is OK
+  # and "fixes up" the chroot.  ...but build_packages will do the fixups
+  # anyway (I think), so this isn't that important.
+  chroot_dir = _GetChrootAbsDir(chroot_config)
+  if (not clean_first) and _DoesChrootExist(chroot_config):
+    Info('%s already exists, skipping make_chroot.' % chroot_dir)
+    return
+
+  Info('MAKING THE CHROOT')
+
+  # Put together command.
+  cmd_list = [
+      './make_chroot',
+      '--chroot="%s"' % chroot_dir,
+      chroot_config.get('CHROOT', 'make_chroot_flags'),
+  ]
+  if clean_first:
+    cmd_list.insert(1, '--replace')
+
+  # We're going convert to a string and force the shell to do all of the
+  # splitting of arguments, since we're throwing all of the flags from the
+  # config file in there.
+  cmd = ' '.join(cmd_list)
+
+  # We'll put CWD as src/scripts when running the command.  Since everyone
+  # running by hand has their cwd there, it is probably the safest.
+  cwd = os.path.join(_SRCROOT_PATH, 'src', 'scripts')
+
+  # Run it.  Exceptions will cause the program to exit.
+  RunCommand(cmd, shell=True, cwd=cwd, ignore_sigint=True)
+
+
+def _DoEnterChroot(chroot_config, fn, *args, **kwargs):
+  """Re-run the given function inside the chroot.
+
+  When the function is run, it will be run in a SEPARATE INSTANCE of chromite,
+  which will be run in the chroot.  This is a little weird.  Specifically:
+  - When the callee executes, it will be a separate python instance.
+    - Globals will be reset back to defaults.
+    - A different version of python (with different modules) may end up running
+      the script in the chroot.
+  - All arguments are pickled up into a temp file, whose path is passed on the
+    command line.
+    - That means that args must be pickleable.
+    - It also means that modifications to the parameters by the callee are not
+      visible to the caller.
+    - Even the function is "pickled".  The way the pickle works, I belive, is it
+      just passes the name of the function.  If this name somehow resolves
+      differently in the chroot, you may get weirdness.
+  - Since we're in the chroot, obviously files may have different paths.  It's
+    up to you to convert parameters if you need to.
+  - The stdin, stdout, and stderr aren't touched.
+
+  Args:
+    chroot_config: A SafeConfigParser representing the config for the chroot.
+    fn: The function to call.
+    args: All other arguments will be passed to the function as is.
+    kwargs: All other arguments will be passed to the function as is.
+  """
+  # Make sure that the chroot exists...
+  chroot_dir = _GetChrootAbsDir(chroot_config)
+  if not _DoesChrootExist(chroot_config):
+    Die('Chroot dir does not exist; try the "build host" command.\n  %s.' %
+        chroot_dir)
+
+  Info('ENTERING THE CHROOT')
+
+  # Save state to a temp file (inside the chroot!) using pickle.
+  tmp_dir = os.path.join(chroot_dir, 'tmp')
+  state_file = tempfile.NamedTemporaryFile(prefix='chromite', dir=tmp_dir)
+  try:
+    cPickle.dump((fn, args, kwargs), state_file, cPickle.HIGHEST_PROTOCOL)
+    state_file.flush()
+
+    # Translate temp file name into a chroot path...
+    chroot_state_path = os.path.join('/tmp', os.path.basename(state_file.name))
+
+    # Put together command.  We're going to force the shell to do all of the
+    # splitting of arguments, since we're throwing all of the flags from the
+    # config file in there.
+    # TODO(dianders): Once chromite is in the path inside the chroot, we should
+    #                 change it from 'chromite/chromite' to just 'chromite'.
+    cmd = (
+        './enter_chroot.sh --chroot="%s" %s --'
+        ' chromite/chromite --resume-state %s') % (
+            chroot_dir,
+            chroot_config.get('CHROOT', 'enter_chroot_flags'),
+            chroot_state_path)
+
+    # We'll put CWD as src/scripts when running the command.  Since everyone
+    # running by hand has their cwd there, it is probably the safest.
+    cwd = os.path.join(_SRCROOT_PATH, 'src', 'scripts')
+
+    # Run it.  We allow "error" so we don't print a confusing error message
+    # filled with out resume-state garbage on control-C.
+    cmd_result = RunCommand(cmd, shell=True, cwd=cwd, print_cmd=False,
+                            exit_code=True, error_ok=True, ignore_sigint=True)
+
+    if cmd_result.returncode:
+      Die('Chroot exited with error code %d' % cmd_result.returncode)
+  finally:
+    # Make sure things get closed (and deleted), even upon exception.
+    state_file.close()
+
+
+def _DoSetupBoard(build_config, clean_first):
+  """Setup the board, if needed.
+
+  This just runs the setup_board command with the proper args, if needed.
+
+  Args:
+    build_config: A SafeConfigParser representing the build config.
+    clean_first: Delete any old board config first.
+  """
+  # Skip this whole command if things already exist.
+  board_dir = _GetBoardDir(build_config)
+  if (not clean_first) and os.path.isdir(board_dir):
+    Info('%s already exists, skipping setup_board.' % board_dir)
+    return
+
+  Info('SETTING UP THE BOARD')
+
+  # Put together command.
+  cmd_list = [
+      './setup_board',
+      '--board="%s"' % build_config.get('BUILD', 'target'),
+      build_config.get('BUILD', 'setup_board_flags'),
+  ]
+  if clean_first:
+    cmd_list.insert(1, '--force')
+
+  # We're going convert to a string and force the shell to do all of the
+  # splitting of arguments, since we're throwing all of the flags from the
+  # config file in there.
+  cmd = ' '.join(cmd_list)
+
+  # We'll put CWD as src/scripts when running the command.  Since everyone
+  # running by hand has their cwd there, it is probably the safest.
+  cwd = os.path.join(_SRCROOT_PATH, 'src', 'scripts')
+
+  # Run it.  Exceptions will cause the program to exit.
+  RunCommand(cmd, shell=True, cwd=cwd, ignore_sigint=True)
+
+
+def _DoBuildPackages(build_config):
+  """Build packages.
+
+  This just runs the build_packages command with the proper args.
+
+  Args:
+    build_config: A SafeConfigParser representing the build config.
+  """
+  Info('BUILDING PACKAGES')
+
+  # Put together command.  We're going to force the shell to do all of the
+  # splitting of arguments, since we're throwing all of the flags from the
+  # config file in there.
+  cmd = './build_packages --board="%s" %s' % (
+      build_config.get('BUILD', 'target'),
+      build_config.get('BUILD', 'build_packages_flags')
+  )
+
+  # We'll put CWD as src/scripts when running the command.  Since everyone
+  # running by hand has their cwd there, it is probably the safest.
+  cwd = os.path.join(_SRCROOT_PATH, 'src', 'scripts')
+
+  # Run it.  Exceptions will cause the program to exit.
+  RunCommand(cmd, shell=True, cwd=cwd, ignore_sigint=True)
+
+
+def _DoBuildImage(build_config):
+  """Build an image.
+
+  This just runs the build_image command with the proper args.
+
+  Args:
+    build_config: A SafeConfigParser representing the build config.
+  """
+  Info('BUILDING THE IMAGE')
+
+  # Put together command.  We're going to force the shell to do all of the
+  # splitting of arguments, since we're throwing all of the flags from the
+  # config file in there.
+  cmd = './build_image --board="%s" %s' % (
+      build_config.get('BUILD', 'target'),
+      build_config.get('IMAGE', 'build_image_flags')
+  )
+
+  # We'll put CWD as src/scripts when running the command.  Since everyone
+  # running by hand has their cwd there, it is probably the safest.
+  cwd = os.path.join(_SRCROOT_PATH, 'src', 'scripts')
+
+  # Run it.  Exceptions will cause the program to exit.
+  RunCommand(cmd, shell=True, cwd=cwd, ignore_sigint=True)
+
+
+def _DoClean(chroot_config, build_config, want_force_yes):
+  """Clean a target.
+
+  Args:
+    chroot_config: A SafeConfigParser representing the config for the chroot.
+    build_config: A SafeConfigParser representing the build config.
+    want_force_yes: If True, we won't ask any questions--we'll just assume
+        that the user really wants to kill the directory.  If False, we'll
+        show UI asking the user to confirm.
+  """
+  # We'll need the directory so we can delete stuff; this is a chroot path.
+  board_dir = _GetBoardDir(build_config)
+
+  # If not in the chroot, convert board_dir into a non-chroot path...
+  if not IsInsideChroot():
+    chroot_dir = _GetChrootAbsDir(chroot_config)
+
+    # We'll need to make the board directory relative to the chroot.
+    assert board_dir.startswith('/'), 'Expected unix-style, absolute path.'
+    board_dir = board_dir.lstrip('/')
+    board_dir = os.path.join(chroot_dir, board_dir)
+
+  if not os.path.isdir(board_dir):
+    Die("Nothing to clean: the board directory doesn't exist.\n  %s" %
+        board_dir)
+
+  if not want_force_yes:
+    sys.stderr.write('\n'
+                     'Board dir is at: %s\n'
+                     'Are you sure you want to delete it (YES/NO)? ' %
+                     board_dir)
+    answer = raw_input()
+    if answer.lower() not in ('y', 'ye', 'yes'):
+      Die("You must answer 'yes' if you want to proceed.")
+
+  # Since we're about to do a sudo rm -rf, these are just extra precautions.
+  # This shouldn't be the only place testing these (assert fails are ugly and
+  # can be turned off), but better safe than sorry.
+  # Note that the restriction on '*' is a bit unnecessary, since no shell
+  # expansion should happen.  ...but again, I'd rather be safe.
+  assert os.path.isabs(board_dir), 'Board dir better be absolute'
+  assert board_dir != '/', 'Board dir better not be /'
+  assert '*' not in board_dir, 'Board dir better not have any *s'
+  assert build_config.get('BUILD', 'target'), 'Target better not be blank'
+  assert build_config.get('BUILD', 'target') in board_dir, \
+         'Target name better be in board dir'
+
+  argv = ['sudo', '--', 'rm', '-rf', board_dir]
+  RunCommand(argv)
+  Info('Deleted: %s' % board_dir)
+
+
+def _DoDistClean(chroot_config, want_force_yes):
+  """Remove the whole chroot.
+
+  Args:
+    chroot_config: A SafeConfigParser representing the config for the chroot.
+    want_force_yes: If True, we won't ask any questions--we'll just assume
+        that the user really wants to kill the directory.  If False, we'll
+        show UI asking the user to confirm.
+  """
+  if IsInsideChroot():
+    Die('Please exit the chroot before trying to delete it.')
+
+  chroot_dir = _GetChrootAbsDir(chroot_config)
+  if not want_force_yes:
+    sys.stderr.write('\n'
+                     'Chroot is at: %s\n'
+                     'Are you sure you want to delete it (YES/NO)? ' %
+                     chroot_dir)
+    answer = raw_input()
+    if answer.lower() not in ('y', 'ye', 'yes'):
+      Die("You must answer 'yes' if you want to proceed.")
+
+  # Can pass argv and not shell=True, since no user flags.  :)
+  argv = ['./make_chroot', '--chroot=%s' % chroot_dir, '--delete']
+
+  # We'll put CWD as src/scripts when running the command.  Since everyone
+  # running by hand has their cwd there, it is probably the safest.
+  cwd = os.path.join(_SRCROOT_PATH, 'src', 'scripts')
+
+  # Run it.  Pass any failures upward.
+  RunCommand(argv, cwd=cwd)
+
+
+def _DoWrappedChrootCommand(target_cmd, host_cmd, raw_argv, need_args=False,
+                            chroot_config=None, argv=None, build_config=None):
+  """Helper function for any command that is simply wrapped by chromite.
+
+  These are commands where:
+  - We parse the command line only enough to figure out what board they
+    want.  All othe command line parsing is handled by the wrapped command.
+    Because of this, the board name _needs_ to be specified first.
+  - Everything else (arg parsing, help, etc) is handled by the wrapped command.
+    The usage string will be a little messed up, but hopefully that's OK.
+
+  Args:
+    target_cmd: We'll put this at the start of argv when calling a target
+        command.  We'll substiture %s with the target.
+        Like - ['my_command-%s'] or ['my_command', '--board=%s']
+    host_cmd: We'll put this at the start of argv when calling a host command.
+        Like - ['my_command']
+    raw_argv: Command line arguments, including this command's name, but not
+        the chromite command name or chromite options.
+    need_args: If True, we'll prompt for arguments if they weren't specified.
+        This makes the most sense when someone runs chromite with no arguments
+        and then walks through the menus.  It's not ideal, but less sucky than
+        just quitting.
+    chroot_config: A SafeConfigParser for the chroot config; or None chromite
+        was called from within the chroot.
+    argv: None when called normally, but contains argv with board stripped off
+        if we call ourselves with _DoEnterChroot().
+    build_config: None when called normally, but contains the SafeConfigParser
+        for the build config if we call ourselves with _DoEnterChroot().  Note
+        that even when called through _DoEnterChroot(), could still be None
+        if user chose 'HOST' as the target.
+  """
+  # If we didn't get called through EnterChroot, we need to read the build
+  # config.
+  if argv is None:
+    # We look for the build config without calling OptionParser.  This means
+    # that the board _needs_ to be first (if it's specified) and all options
+    # will be passed straight to our subcommand.
+    argv, build_config = _GetBuildConfigFromArgs(raw_argv[1:])
+
+  # Enter the chroot if needed...
+  if not IsInsideChroot():
+    _DoEnterChroot(chroot_config, _DoWrappedChrootCommand, target_cmd, host_cmd,
+                   raw_argv, need_args=need_args, argv=argv,
+                   build_config=build_config)
+  else:
+    # We'll put CWD as src/scripts when running the command.  Since everyone
+    # running by hand has their cwd there, it is probably the safest.
+    cwd = os.path.join(_SRCROOT_PATH, 'src', 'scripts')
+
+    # Get command to call.  If build_config is None, it means host.
+    if build_config is None:
+      argv_prefix = host_cmd
+    else:
+      # Make argv_prefix w/ target.
+      target_name = build_config.get('BUILD', 'target')
+      argv_prefix = [arg % target_name for arg in target_cmd]
+
+    # Not a great way to to specify arguments, but works for now...  Wrapped
+    # commands are not wonderful interfaces anyway...
+    if need_args and not argv:
+      while True:
+        sys.stderr.write('arg %d (blank to exit): ' % (len(argv)+1))
+        arg = raw_input()
+        if not arg:
+          break
+        argv.append(arg)
+
+    # Add the prefix...
+    argv = argv_prefix + argv
+
+    # Run, ignoring errors since some commands (ahem, cros_workon) seem to
+    # return errors from things like --help.
+    RunCommand(argv, cwd=cwd, ignore_sigint=True, error_ok=True)
+
+
+def _CmdBuild(raw_argv, chroot_config=None, loaded_config=False,
+              build_config=None):
+  """Build the chroot (if needed), the packages for a target, and the image.
+
+  Args:
+    raw_argv: Command line arguments, including this command's name, but not
+        the chromite command name or chromite options.
+    chroot_config: A SafeConfigParser for the chroot config; or None chromite
+        was called from within the chroot.
+    loaded_config: If True, we've already loaded the config.
+    build_config: None when called normally, but contains the SafeConfigParser
+        for the build config if we call ourselves with _DoEnterChroot().  Note
+        that even when called through _DoEnterChroot(), could still be None
+        if user chose 'HOST' as the target.
+  """
+  # Parse options for command...
+  usage_str = ('usage: %%prog [chromite_options] %s [options] [target]' %
+               raw_argv[0])
+  parser = optparse.OptionParser(usage=usage_str)
+  parser.add_option('--clean', default=False, action='store_true',
+                    help='Clean before building.')
+  (options, argv) = parser.parse_args(raw_argv[1:])
+
+  # Load the build config if needed...
+  if not loaded_config:
+    argv, build_config = _GetBuildConfigFromArgs(argv)
+    if argv:
+      Die('Unknown arguments: %s' % ' '.join(argv))
+
+  if not IsInsideChroot():
+    # Note: we only want to clean the chroot if they do --clean and have the
+    # host target.  If they do --clean and have a board target, it means
+    # that they just want to clean the board...
+    want_clean_chroot = options.clean and build_config is None
+
+    _DoMakeChroot(chroot_config, want_clean_chroot)
+
+    if build_config is not None:
+      _DoEnterChroot(chroot_config, _CmdBuild, raw_argv,
+                     build_config=build_config, loaded_config=True)
+
+    Info('Done building.')
+  else:
+    if build_config is None:
+      Die("You can't build the host chroot from within the chroot.")
+
+    _DoSetupBoard(build_config, options.clean)
+    _DoBuildPackages(build_config)
+    _DoBuildImage(build_config)
+
+
+def _CmdWorkon(raw_argv, *args, **kwargs):
+  """Run cros_workon.
+
+  This is just a wrapped command.
+
+  Args:
+    raw_argv: Command line arguments, including this command's name, but not
+        the chromite command name or chromite options.
+    args: The rest of the positional arguments.  See _DoWrappedChrootCommand.
+    kwargs: The keyword arguments.  See _DoWrappedChrootCommand.
+  """
+  # Slight optimization, just since I do this all the time...
+  if len(raw_argv) >= 2:
+    if raw_argv[1] in ('start', 'stop', 'list', 'list-all', 'iterate'):
+      Warn('OOPS, looks like you forgot a board name. Pick one.')
+      raw_argv = raw_argv[:1] + [''] + raw_argv[1:]
+
+  # Note that host version uses "./", since it's in src/scripts and not in the
+  # path...
+  _DoWrappedChrootCommand(['cros_workon-%s'], ['./cros_workon', '--host'],
+                          raw_argv, need_args=True, *args, **kwargs)
+
+
+def _CmdEbuild(raw_argv, *args, **kwargs):
+  """Run ebuild.
+
+  This is just a wrapped command.
+
+  Args:
+    raw_argv: Command line arguments, including this command's name, but not
+        the chromite command name or chromite options.
+    args: The rest of the positional arguments.  See _DoWrappedChrootCommand.
+    kwargs: The keyword arguments.  See _DoWrappedChrootCommand.
+  """
+  _DoWrappedChrootCommand(['ebuild-%s'], ['ebuild'],
+                          raw_argv, need_args=True, *args, **kwargs)
+
+
+def _CmdEmerge(raw_argv, *args, **kwargs):
+  """Run emerge.
+
+  This is just a wrapped command.
+
+  Args:
+    raw_argv: Command line arguments, including this command's name, but not
+        the chromite command name or chromite options.
+    args: The rest of the positional arguments.  See _DoWrappedChrootCommand.
+    kwargs: The keyword arguments.  See _DoWrappedChrootCommand.
+  """
+  _DoWrappedChrootCommand(['emerge-%s'], ['emerge'],
+                          raw_argv, need_args=True, *args, **kwargs)
+
+
+def _CmdEquery(raw_argv, *args, **kwargs):
+  """Run equery.
+
+  This is just a wrapped command.
+
+  Args:
+    raw_argv: Command line arguments, including this command's name, but not
+        the chromite command name or chromite options.
+    args: The rest of the positional arguments.  See _DoWrappedChrootCommand.
+    kwargs: The keyword arguments.  See _DoWrappedChrootCommand.
+  """
+  _DoWrappedChrootCommand(['equery-%s'], ['equery'],
+                          raw_argv, need_args=True, *args, **kwargs)
+
+
+def _CmdPortageq(raw_argv, *args, **kwargs):
+  """Run portageq.
+
+  This is just a wrapped command.
+
+  Args:
+    raw_argv: Command line arguments, including this command's name, but not
+        the chromite command name or chromite options.
+    args: The rest of the positional arguments.  See _DoWrappedChrootCommand.
+    kwargs: The keyword arguments.  See _DoWrappedChrootCommand.
+  """
+  _DoWrappedChrootCommand(['portageq-%s'], ['portageq'],
+                          raw_argv, need_args=True, *args, **kwargs)
+
+
+def _CmdShell(raw_argv, chroot_config=None):
+  """Start a shell in the chroot.
+
+  This can either just start a simple interactive shell, it can be used to
+  run an arbirtary command inside the chroot and then exit.
+
+  Args:
+    raw_argv: Command line arguments, including this command's name, but not
+        the chromite command name or chromite options.
+    chroot_config: A SafeConfigParser for the chroot config; or None chromite
+        was called from within the chroot.
+  """
+  # Parse options for command...
+  # ...note that OptionParser will eat the '--' if it's there, which is what
+  # we want..
+  usage_str = ('usage: %%prog [chromite_options] %s [options] [VAR=value] '
+               '[-- command [arg1] [arg2] ...]') % raw_argv[0]
+  parser = optparse.OptionParser(usage=usage_str)
+  (_, argv) = parser.parse_args(raw_argv[1:])
+
+  # Enter the chroot if needed...
+  if not IsInsideChroot():
+    _DoEnterChroot(chroot_config, _CmdShell, raw_argv)
+  else:
+    # We'll put CWD as src/scripts when running the command.  Since everyone
+    # running by hand has their cwd there, it is probably the safest.
+    cwd = os.path.join(_SRCROOT_PATH, 'src', 'scripts')
+
+    # By default, no special environment...
+    env = None
+
+    if not argv:
+      # If no arguments, we'll just start bash.
+      argv = ['bash']
+    else:
+      # Parse the command line, looking at the beginning for VAR=value type
+      # statements.  I couldn't figure out a way to get bash to do this for me.
+      user_env, argv = _SplitEnvFromArgs(argv)
+      if not argv:
+        Die('No command specified')
+
+      # If there was some environment, use it to override the standard
+      # environment.
+      if user_env:
+        env = dict(os.environ)
+        env.update(user_env)
+
+    # Don't show anything special for errors; we'll let the shell report them.
+    RunCommand(argv, cwd=cwd, env=env, error_ok=True, ignore_sigint=True)
+
+
+def _CmdClean(raw_argv, chroot_config=None):
+  """Clean out built packages for a target; if target is host, deletes chroot.
+
+  Args:
+    raw_argv: Command line arguments, including this command's name, but not
+        the chromite command name or chromite options.
+    chroot_config: A SafeConfigParser for the chroot config; or None chromite
+        was called from within the chroot.
+  """
+  # Parse options for command...
+  usage_str = ('usage: %%prog [chromite_options] %s [options] [target]' %
+               raw_argv[0])
+  parser = optparse.OptionParser(usage=usage_str)
+  parser.add_option('-y', '--yes', default=False, action='store_true',
+                    help='Answer "YES" to "are you sure?" questions.')
+  (options, argv) = parser.parse_args(raw_argv[1:])
+
+  # Make sure the chroot exists first, before possibly prompting for board...
+  # ...not really required, but nice for the user...
+  if not IsInsideChroot():
+    if not _DoesChrootExist(chroot_config):
+      Die("Nothing to clean: the chroot doesn't exist.\n  %s" %
+          _GetChrootAbsDir(chroot_config))
+
+  # Load the build config...
+  argv, build_config = _GetBuildConfigFromArgs(argv)
+  if argv:
+    Die('Unknown arguments: %s' % ' '.join(argv))
+
+  # If they do clean host, we'll delete the whole chroot
+  if build_config is None:
+    _DoDistClean(chroot_config, options.yes)
+  else:
+    _DoClean(chroot_config, build_config, options.yes)
+
+
+def main():
+  # TODO(dianders): Make help a little better.  Specifically:
+  # 1. Add a command called 'help'
+  # 2. Make the help string below include command list and descriptions (like
+  #    the menu, but without being interactive).
+  # 3. Make "help command" and "--help command" equivalent to "command --help".
+  help_str = (
+      """Usage: %(prog)s [chromite_options] [cmd [args]]\n"""
+      """\n"""
+      """The chromite script is a wrapper to make it easy to do various\n"""
+      """build tasks.  For a list of commands, run without any arguments.\n"""
+      """\n"""
+      """Options:\n"""
+      """  -h, --help            show this help message and exit\n"""
+  ) % {'prog': os.path.basename(sys.argv[0])}
+  if not IsInsideChroot():
+    help_str += (
+        """  --chroot=CHROOT_NAME  Chroot spec to use. Can be an absolute\n"""
+        """                        path to a spec file or a substring of a\n"""
+        """                        chroot spec name (without .spec suffix)\n"""
+    )
+
+  # We don't use OptionParser here, since options for different subcommands are
+  # so different.  We just look for the chromite options here...
+  if sys.argv[1:2] == ['--help']:
+    print help_str
+    sys.exit(0)
+  elif sys.argv[1:2] == ['--resume-state']:
+    # Internal mechanism (not documented to users) to resume in the chroot.
+    # ...actual resume state file is passed in sys.argv[2] for simplicity...
+    assert len(sys.argv) == 3, 'Resume State not passed properly.'
+    fn, args, kwargs = cPickle.load(open(sys.argv[2], 'rb'))
+    fn(*args, **kwargs)
+  else:
+    # Start by skipping argv[0]
+    argv = sys.argv[1:]
+
+    # Look for special "--chroot" argument to allow for alternate chroots
+    if not IsInsideChroot():
+      # Default chroot name...
+      chroot_name = 'chroot'
+
+      # Get chroot spec name if specified; trim argv down if needed...
+      if argv:
+        if argv[0].startswith('--chroot='):
+          _, chroot_name = argv[0].split('=', 2)
+          argv = argv[1:]
+        elif argv[0] == '--chroot':
+          if len(argv) < 2:
+            Die('Chroot not specified.')
+
+          chroot_name = argv[1]
+          argv = argv[2:]
+
+      chroot_spec_path = _FindSpec(chroot_name, spec_type=_CHROOT_SPEC_TYPE)
+
+      Info('Using chroot "%s"' % os.path.relpath(chroot_spec_path))
+
+      chroot_config = _ReadConfig(chroot_spec_path)
+    else:
+      # Already in the chroot; no need to get config...
+      chroot_config = None
+
+    # Get command and arguments
+    if argv:
+      chromite_cmd = argv[0].lower()
+      argv = argv[1:]
+    else:
+      chromite_cmd = ''
+
+    # Validate the chromite_cmd, popping a menu if needed.
+    chromite_cmd = _FindCommand(chromite_cmd)
+
+    # Finally, call the function w/ standard argv.
+    cmd_fn = eval(_COMMAND_HANDLERS[_COMMAND_STRS.index(chromite_cmd)])
+    cmd_fn([chromite_cmd] + argv, chroot_config=chroot_config)
+
+
+if __name__ == '__main__':
+  main()