# Copyright 2011 Google Inc. All Rights Reserved.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
#     http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.

import boto
import datetime
import multiprocessing
import platform
import os
import signal
import sys
import time
import webbrowser

from boto.provider import Provider
from gslib.command import Command
from gslib.command import COMMAND_NAME
from gslib.command import COMMAND_NAME_ALIASES
from gslib.command import CONFIG_REQUIRED
from gslib.command import FILE_URIS_OK
from gslib.command import MAX_ARGS
from gslib.command import MIN_ARGS
from gslib.command import PROVIDER_URIS_OK
from gslib.command import SUPPORTED_SUB_ARGS
from gslib.command import URIS_START_ARG
from gslib.exception import AbortException
from gslib.exception import CommandException
from gslib.help_provider import HELP_NAME
from gslib.help_provider import HELP_NAME_ALIASES
from gslib.help_provider import HELP_ONE_LINE_SUMMARY
from gslib.help_provider import HELP_TEXT
from gslib.help_provider import HelpType
from gslib.help_provider import HELP_TYPE
from gslib.util import HAVE_OAUTH2
from gslib.util import TWO_MB

_detailed_help_text = ("""
<B>SYNOPSIS</B>
  gsutil [-D] config [-a] [-b] [-f] [-o <file>] [-r] [-s <scope>] [-w]


<B>DESCRIPTION</B>
  The gsutil config command obtains access credentials for Google Cloud
  Storage and writes a boto/gsutil configuration file containing the obtained
  credentials along with a number of other configuration-controllable values.

  Unless specified otherwise (see OPTIONS), the configuration file is written
  to ~/.boto (i.e., the file .boto under the user's home directory). If the
  default file already exists, an attempt is made to rename the existing file
  to ~/.boto.bak; if that attempt fails the command will exit. A different
  destination file can be specified with the -o option (see OPTIONS).

  Because the boto configuration file contains your credentials you should
  keep its file permissions set so no one but you has read access. (The file
  is created read-only when you run gsutil config.)


<B>CREDENTIALS</B>
  By default gsutil config obtains OAuth2 credentials, and writes them
  to the [Credentials] section of the configuration file. The -r, -w,
  -f options (see OPTIONS below) cause gsutil config to request a token
  with restricted scope; the resulting token will be restricted to read-only
  operations, read-write operation, or all operations (including getacl/setacl/
  getdefacl/setdefacl/disablelogging/enablelogging/getlogging operations). In
  addition, -s <scope> can be used to request additional (non-Google-Storage)
  scopes.

  If you want to use credentials based on access key and secret (the older
  authentication method before OAuth2 was supported) instead of OAuth2,
  see help about the -a option in the OPTIONS section.

  If you wish to use gsutil with other providers (or to copy data back and
  forth between multiple providers) you can edit their credentials into the
  [Credentials] section after creating the initial configuration file.


<B>CONFIGURATION FILE SELECTION PROCEDURE</B>
  By default, gsutil will look for the configuration file in /etc/boto.cfg and
  ~/.boto. You can override this choice by setting the BOTO_CONFIG environment
  variable. This is also useful if you have several different identities or
  cloud storage environments: By setting up the credentials and any additional
  configuration in separate files for each, you can switch environments by
  changing environment variables.

  You can also set up a path of configuration files, by setting the BOTO_PATH
  environment variable to contain a ":" delimited path. For example setting
  the BOTO_PATH environment variable to:

    /etc/projects/my_group_project.boto.cfg:/home/mylogin/.boto

  will cause gsutil to load each configuration file found in the path in
  order. This is useful if you want to set up some shared configuration
  state among many users: The shared state can go in the central shared file
  ( /etc/projects/my_group_project.boto.cfg) and each user's individual
  credentials can be placed in the configuration file in each of their home
  directories. (For security reasons users should never share credentials
  via a shared configuration file.)


<B>CONFIGURATION FILE STRUCTURE</B>
  The configuration file contains a number of sections: [Credentials],
  [Boto], [GSUtil], and [OAuth2]. If you edit the file make sure to edit the
  appropriate section (discussed below), and to be careful not to mis-edit
  any of the setting names (like "gs_access_key_id") and not to remove the
  section delimiters (like "[Credentials]").


<B>ADDITIONAL CONFIGURATION-CONTROLLABLE FEATURES</B>
  With the exception of setting up gsutil to work through a proxy (see
  below), most users won't need to edit values in the boto configuration file;
  values found in there tend to be of more specialized use than command line
  option-controllable features.

  The following are the currently defined configuration settings, broken
  down by section. Their use is documented in comments preceding each, in
  the configuration file. If you see a setting you want to change that's not
  listed in your current file, see the section below on Updating to the Latest
  Configuration File.

  The currently supported settings, are, by section:
  [Boto]
    proxy
    proxy_port
    proxy_user
    proxy_pass
    is_secure
    https_validate_certificates
    send_crlf_after_proxy_auth_headers
    debug
    num_retries

  [GSUtil]
    resumable_threshold
    resumable_tracker_dir
    parallel_process_count
    parallel_thread_count
    default_api_version
    default_project_id
    use_magicfile

  [OAuth2]
    token_cache
    token_cache
    client_id
    client_secret
    provider_label
    provider_authorization_uri
    provider_token_uri


<B>UPDATING TO THE LATEST CONFIGURATION FILE</B>
  We add new configuration controllable features to the boto configuration file
  over time, but most gsutil users create a configuration file once and then
  keep it for a long time, so new features aren't apparent when you update
  to a newer version of gsutil. If you want to get the latest configuration
  file (which includes all the latest settings and documentation about each)
  you can rename your current file (e.g., to '.boto_old'), run gsutil config,
  and then edit any configuration settings you wanted from your old file
  into the newly created file. Note, however, that if you're using OAuth2
  credentials and you go back through the OAuth2 configuration dialog it will
  invalidate your previous OAuth2 credentials.

  If no explicit scope option is given, -f (full control) is assumed by default.


<B>OPTIONS</B>
  -a          Prompt for Google Cloud Storage access key and secret (the older
              authentication method before OAuth2 was supported) instead of
              obtaining an OAuth2 token.

  -b          Causes gsutil config to launch a browser to obtain OAuth2 approval
              and the project ID instead of showing the URL for each and asking
              the user to open the browser. This will probably not work as
              expected if you are running gsutil from an ssh window, or using
              gsutil on Windows.

  -f          Request token with full-control access (default).

  -o <file>   Write the configuration to <file> instead of ~/.boto.
              Use '-' for stdout.

  -r          Request token restricted to read-only access.

  -s <scope>  Request additional OAuth2 <scope>.

  -w          Request token restricted to read-write access.
""")


try:
  from oauth2_plugin import oauth2_helper
except ImportError:
  pass

GOOG_API_CONSOLE_URI = 'http://code.google.com/apis/console'

SCOPE_FULL_CONTROL = 'https://www.googleapis.com/auth/devstorage.full_control'
SCOPE_READ_WRITE = 'https://www.googleapis.com/auth/devstorage.read_write'
SCOPE_READ_ONLY = 'https://www.googleapis.com/auth/devstorage.read_only'

CONFIG_PRELUDE_CONTENT = """
# This file contains credentials and other configuration information needed
# by the boto library, used by gsutil. You can edit this file (e.g., to add
# credentials) but be careful not to mis-edit any of the variable names (like
# "gs_access_key_id") or remove important markers (like the "[Credentials]" and
# "[Boto]" section delimiters).
#
"""

# Default number of OS processes and Python threads for parallel operations.
# On Linux systems we automatically scale the number of processes to match
# the underlying CPU/core count. Given we'll be running multiple concurrent
# processes on a typical multi-core Linux computer, to avoid being too
# aggressive with resources, the default number of threads is reduced from
# the previous value of 24 to 10.
# On Windows and Mac systems parallel multi-processing and multi-threading
# in Python presents various challenges so we retain compatibility with
# the established parallel mode operation, i.e. one process and 24 threads.
if platform.system() == 'Linux':
  DEFAULT_PARALLEL_PROCESS_COUNT = multiprocessing.cpu_count()
  DEFAULT_PARALLEL_THREAD_COUNT = 10
else:
  DEFAULT_PARALLEL_PROCESS_COUNT = 1
  DEFAULT_PARALLEL_THREAD_COUNT = 24

CONFIG_BOTO_SECTION_CONTENT = """
[Boto]

# To use a proxy, edit and uncomment the proxy and proxy_port lines. If you
# need a user/password with this proxy, edit and uncomment those lines as well.
#proxy = <proxy host>
#proxy_port = <proxy port>
#proxy_user = <your proxy user name>
#proxy_pass = <your proxy password>

# The following two options control the use of a secure transport for requests
# to S3 and Google Cloud Storage. It is highly recommended to set both options
# to True in production environments, especially when using OAuth2 bearer token
# authentication with Google Cloud Storage.

# Set 'is_secure' to False to cause boto to connect using HTTP instead of the
# default HTTPS. This is useful if you want to capture/analyze traffic
# (e.g., with tcpdump). This option should always be set to True in production
# environments.
#is_secure = False

# Set 'https_validate_certificates' to False to disable server certificate
# checking. The default for this option in the boto library is currently
# 'False' (to avoid breaking apps that depend on invalid certificates); it is
# therefore strongly recommended to always set this option explicitly to True
# in configuration files, to protect against "man-in-the-middle" attacks.
https_validate_certificates = True

# Set 'send_crlf_after_proxy_auth_headers' to True if you encounter problems
# tunneling HTTPS through a proxy. Users who don't have a proxy in the path
# to Google Cloud Storage don't need to touch this. Users who use a proxy will
# probably find that the default behavior (flag value False) works. If
# you encounter an error like "EOF occurred in violation of protocol" while
# trying to use gsutil through your proxy, try setting this flag to True. We
# (gs-team@google.com) would be interested to hear from you if you need to set
# this, including the make and version of the proxy server you are using.
#send_crlf_after_proxy_auth_headers = False

# 'debug' controls the level of debug messages printed: 0 for none, 1
# for basic boto debug, 2 for all boto debug plus HTTP requests/responses.
# Note: 'gsutil -d' sets debug to 2 for that one command run.
#debug = <0, 1, or 2>

# 'num_retries' controls the number of retry attempts made when errors occur.
# The default is 6. Note: don't set this value to 0, as it will cause boto to
# fail when reusing HTTP connections.
#num_retries = <integer value>
"""

CONFIG_INPUTLESS_GSUTIL_SECTION_CONTENT = """
[GSUtil]

# 'resumable_threshold' specifies the smallest file size [bytes] for which
# resumable Google Cloud Storage transfers are attempted. The default is 2097152
# (2 MiB).
#resumable_threshold = %(resumable_threshold)d

# 'resumable_tracker_dir' specifies the base location where resumable
# transfer tracker files are saved. By default they're in ~/.gsutil
#resumable_tracker_dir = <file path>

# 'parallel_process_count' and 'parallel_thread_count' specify the number
# of OS processes and Python threads, respectively, to use when executing
# operations in parallel. The default settings should work well as configured,
# however, to enhance performance for transfers involving large numbers of
# files, you may experiment with hand tuning these values to optimize
# performance for your particular system configuration.
# MacOS and Windows users should see
# http://code.google.com/p/gsutil/issues/detail?id=78 before attempting
# to experiment with these values.
#parallel_process_count = %(parallel_process_count)d
#parallel_thread_count = %(parallel_thread_count)d

# 'use_magicfile' specifies if the 'file --mime-type <filename>' command should
# be used to guess content types instead of the default filename extension-based
# mechanism. Available on UNIX and MacOS (and possibly on Windows, if you're
# running Cygwin or some other package that provides implementations of
# UNIX-like commands). When available and enabled use_magicfile should be more
# robust because it analyzes file contents in addition to extensions.
#use_magicfile = False

# 'content_language' specifies the ISO 639-1 language code of the content, to be
# passed in the Content-Language header. By default no Content-Language is sent.
# See the ISO 631-1 column of
# http://www.loc.gov/standards/iso639-2/php/code_list.php for a list of
# language codes.
content_language = en
""" % {'resumable_threshold': TWO_MB,
       'parallel_process_count': DEFAULT_PARALLEL_PROCESS_COUNT,
       'parallel_thread_count': DEFAULT_PARALLEL_THREAD_COUNT}

CONFIG_OAUTH2_CONFIG_CONTENT = """
[OAuth2]
# This section specifies options used with OAuth2 authentication.

# 'token_cache' specifies how the OAuth2 client should cache access tokens.
# Valid values are:
#  'in_memory': an in-memory cache is used. This is only useful if the boto
#      client instance (and with it the OAuth2 plugin instance) persists
#      across multiple requests.
#  'file_system' : access tokens will be cached in the file system, in files
#      whose names include a key derived from the refresh token the access token
#      based on.
# The default is 'file_system'.
#token_cache = file_system
#token_cache = in_memory

# 'token_cache_path_pattern' specifies a path pattern for token cache files.
# This option is only relevant if token_cache = file_system.
# The value of this option should be a path, with place-holders '%(key)s' (which
# will be replaced with a key derived from the refresh token the cached access
# token was based on), and (optionally), %(uid)s (which will be replaced with
# the UID of the current user, if available via os.getuid()).
# Note that the config parser itself interpolates '%' placeholders, and hence
# the above placeholders need to be escaped as '%%(key)s'.
# The default value of this option is
#  token_cache_path_pattern = <tmpdir>/oauth2client-tokencache.%%(uid)s.%%(key)s
# where <tmpdir> is the system-dependent default temp directory.

# The following options specify the OAuth2 client identity and secret that is
# used when requesting and using OAuth2 tokens. If not specified, a default
# OAuth2 client for the gsutil tool is used; for uses of the boto library (with
# OAuth2 authentication plugin) in other client software, it is recommended to
# use a tool/client-specific OAuth2 client. For more information on OAuth2, see
# http://code.google.com/apis/accounts/docs/OAuth2.html
#client_id = <OAuth2 client id>
#client_secret = <OAuth2 client secret>

# The following options specify the label and endpoint URIs for the OAUth2
# authorization provider being used. Primarily useful for tool developers.
#provider_label = Google
#provider_authorization_uri = https://accounts.google.com/o/oauth2/auth
#provider_token_uri = https://accounts.google.com/o/oauth2/token
"""

class ConfigCommand(Command):
  """Implementation of gsutil config command."""

  # Command specification (processed by parent class).
  command_spec = {
    # Name of command.
    COMMAND_NAME : 'config',
    # List of command name aliases.
    COMMAND_NAME_ALIASES : ['cfg', 'conf', 'configure'],
    # Min number of args required by this command.
    MIN_ARGS : 0,
    # Max number of args required by this command, or NO_MAX.
    MAX_ARGS : 0,
    # Getopt-style string specifying acceptable sub args.
    SUPPORTED_SUB_ARGS : 'habfwrs:o:',
    # True if file URIs acceptable for this command.
    FILE_URIS_OK : False,
    # True if provider-only URIs acceptable for this command.
    PROVIDER_URIS_OK : False,
    # Index in args of first URI arg.
    URIS_START_ARG : 0,
    # True if must configure gsutil before running command.
    CONFIG_REQUIRED : False,
  }
  help_spec = {
    # Name of command or auxiliary help info for which this help applies.
    HELP_NAME : 'config',
    # List of help name aliases.
    HELP_NAME_ALIASES : ['cfg', 'conf', 'configure', 'proxy', 'aws', 's3'],
    # Type of help:
    HELP_TYPE : HelpType.COMMAND_HELP,
    # One line summary of this help.
    HELP_ONE_LINE_SUMMARY : 'Obtain credentials and create configuration file',
    # The full help text.
    HELP_TEXT : _detailed_help_text,
  }

  def _OpenConfigFile(self, file_path):
    """Creates and opens a configuration file for writing.

    The file is created with mode 0600, and attempts to open existing files will
    fail (the latter is important to prevent symlink attacks).

    It is the caller's responsibility to close the file.

    Args:
      file_path: Path of the file to be created.

    Returns:
      A writable file object for the opened file.

    Raises:
      CommandException: if an error occurred when opening the file (including
          when the file already exists).
    """
    flags = os.O_RDWR | os.O_CREAT | os.O_EXCL
    # Accommodate Windows; stolen from python2.6/tempfile.py.
    if hasattr(os, 'O_NOINHERIT'):
      flags |= os.O_NOINHERIT
    try:
      fd = os.open(file_path, flags, 0600)
    except (OSError, IOError), e:
      raise CommandException('Failed to open %s for writing: %s' %
                             (file_path, e))
    return os.fdopen(fd, 'w')

  def _WriteBotoConfigFile(self, config_file, use_oauth2=True,
      launch_browser=True, oauth2_scopes=[SCOPE_FULL_CONTROL]):
    """Creates a boto config file interactively.

    Needed credentials are obtained interactively, either by asking the user for
    access key and secret, or by walking the user through the OAuth2 approval
    flow.

    Args:
      config_file: File object to which the resulting config file will be
          written.
      use_oauth2: If True, walk user through OAuth2 approval flow and produce a
          config with an oauth2_refresh_token credential. If false, ask the
          user for access key and secret.
      launch_browser: In the OAuth2 approval flow, attempt to open a browser
          window and navigate to the approval URL.
      oauth2_scopes: A list of OAuth2 scopes to request authorization for, when
          using OAuth2.
    """

    # Collect credentials
    provider_map = {'aws': 'aws', 'google': 'gs'}
    uri_map = {'aws': 's3', 'google': 'gs'}
    key_ids = {}
    sec_keys = {}
    if use_oauth2:
      oauth2_refresh_token = oauth2_helper.OAuth2ApprovalFlow(
          oauth2_helper.OAuth2ClientFromBotoConfig(boto.config),
          oauth2_scopes, launch_browser)
    else:
      got_creds = False
      for provider in provider_map:
        if provider == 'google':
          key_ids[provider] = raw_input('What is your %s access key ID? ' %
                                        provider)
          sec_keys[provider] = raw_input('What is your %s secret access key? ' %
                                         provider)
          got_creds = True
          if not key_ids[provider] or not sec_keys[provider]:
            raise CommandException(
                'Incomplete credentials provided. Please try again.')
      if not got_creds:
        raise CommandException('No credentials provided. Please try again.')

    # Write the config file prelude.
    config_file.write(CONFIG_PRELUDE_CONTENT.lstrip())
    config_file.write(
        '# This file was created by gsutil version %s at %s.\n'
        % (self.gsutil_ver,
           datetime.datetime.now().strftime('%Y-%m-%d %H:%M:%S')))
    config_file.write('#\n# You can create additional configuration files by '
        'running\n# gsutil config [options] [-o <config-file>]\n\n\n')

    # Write the config file Credentials section.
    config_file.write('[Credentials]\n\n')
    if use_oauth2:
      config_file.write('# Google OAuth2 credentials (for "gs://" URIs):\n')
      config_file.write('# The following OAuth2 token is authorized for '
          'scope(s):\n')
      for scope in oauth2_scopes:
        config_file.write('#     %s\n' % scope)
      config_file.write('gs_oauth2_refresh_token = %s\n\n' %
          oauth2_refresh_token.refresh_token)
    else:
      config_file.write('# To add Google OAuth2 credentials ("gs://" URIs), '
          'edit and uncomment the\n# following line:\n'
          '#gs_oauth2_refresh_token = <your OAuth2 refresh token>\n\n')

    for provider in provider_map:
      key_prefix = provider_map[provider]
      uri_scheme = uri_map[provider]
      if provider in key_ids and provider in sec_keys:
        config_file.write('# %s credentials ("%s://" URIs):\n' %
                  (provider, uri_scheme))
        config_file.write('%s_access_key_id = %s\n' %
            (key_prefix, key_ids[provider]))
        config_file.write('%s_secret_access_key = %s\n' %
            (key_prefix, sec_keys[provider]))
      else:
        config_file.write('# To add %s credentials ("%s://" URIs), edit and '
                  'uncomment the\n# following two lines:\n'
                  '#%s_access_key_id = <your %s access key ID>\n'
                  '#%s_secret_access_key = <your %s secret access key>\n' %
                  (provider, uri_scheme, key_prefix, provider, key_prefix,
                   provider))
      host_key = Provider.HostKeyMap[provider]
      config_file.write('# The ability to specify an alternate storage host '
                'is primarily for cloud\n# storage service developers.\n'
                '#%s_host = <alternate storage host address>\n\n' % host_key)

    # Write the config file Boto section.
    config_file.write('%s\n' % CONFIG_BOTO_SECTION_CONTENT)

    # Write the config file GSUtil section that doesn't depend on user input.
    config_file.write(CONFIG_INPUTLESS_GSUTIL_SECTION_CONTENT)

    # Write the default API version.
    config_file.write("""
# 'default_api_version' specifies the default Google Cloud Storage API
# version to use. If not set below gsutil defaults to API version 1.
""")
    api_version = 2
    if not use_oauth2: api_version = 1

    config_file.write('default_api_version = %d\n' % api_version)

    # Write the config file GSUtil section that includes the default
    # project ID input from the user.
    if launch_browser:
      sys.stdout.write(
          'Attempting to launch a browser to open the Google API console at '
          'URL: %s\n\n'
          '[Note: due to a Python bug, you may see a spurious error message '
          '"object is not\n callable [...] in [...] Popen.__del__" which can '
          'be ignored.]\n\n' % GOOG_API_CONSOLE_URI)
      sys.stdout.write(
          'In your browser you should see the API Console. Click "Storage" and '
          'look for the value under "Identifying your project\n\n')
      if not webbrowser.open(GOOG_API_CONSOLE_URI, new=1, autoraise=True):
        sys.stdout.write(
            'Launching browser appears to have failed; please navigate a '
            'browser to the following URL:\n%s\n' % GOOG_API_CONSOLE_URI)
      # Short delay; webbrowser.open on linux insists on printing out a message
      # which we don't want to run into the prompt for the auth code.
      time.sleep(2)
    else:
      sys.stdout.write(
          '\nPlease navigate your browser to %s,\nthen click "Services" on the '
          'left side panel and ensure you have Google Cloud\nStorage'
          'activated, then click "Google Cloud Storage" on the left side '
          'panel and\nfind the "x-goog-project-id" on that page.\n' %
          GOOG_API_CONSOLE_URI)
    default_project_id = raw_input('What is your project-id? ')
    project_id_section_prelude = """
# 'default_project_id' specifies the default Google Cloud Storage project ID to
# use with the 'mb' and 'ls' commands. If defined it overrides the default value
# you set in the API Console. Either of these defaults can be overridden
# by specifying the -p option to the 'mb' and 'ls' commands.
"""
    if default_project_id:
      config_file.write('%sdefault_project_id = %s\n\n\n' %
                        (project_id_section_prelude, default_project_id))
    else:
      sys.stderr.write('No default project ID entered. You will need to edit '
                       'the default_project_id value\nin your boto config file '
                       'before using "gsutil ls gs://" or "mb" commands'
                       'with the\ndefault API version (2).\n')
      config_file.write('%s#default_project_id = <value>\n\n\n' %
                        project_id_section_prelude)

    # Write the config file OAuth2 section.
    config_file.write(CONFIG_OAUTH2_CONFIG_CONTENT)

  # Command entry point.
  def RunCommand(self):
    scopes = []
    use_oauth2 = True
    launch_browser = False
    output_file_name = None
    for opt, opt_arg in self.sub_opts:
      if opt == '-a':
        use_oauth2 = False
      elif opt == '-b':
        launch_browser = True
      elif opt == '-f':
        scopes.append(SCOPE_FULL_CONTROL)
      elif opt == '-o':
        output_file_name = opt_arg
      elif opt == '-r':
        scopes.append(SCOPE_READ_ONLY)
      elif opt == '-s':
        scopes.append(opt_arg)
      elif opt == '-w':
        scopes.append(SCOPE_READ_WRITE)

    if use_oauth2 and not HAVE_OAUTH2:
      raise CommandException(
          'OAuth2 is only supported when running under Python 2.6 or later\n'
          '(unless additional dependencies are installed, '
          'see README for details);\n'
          'you are running Python %s.\nUse "gsutil config -a" to create a '
          'config with Developer Key authentication credentials.' % sys.version)

    if not scopes:
      scopes.append(SCOPE_FULL_CONTROL)

    if output_file_name is None:
      # Check to see if a default config file name is requested via
      # environment variable. If so, use it, otherwise use the hard-coded
      # default file. Then use the default config file name, if it doesn't 
      # exist or can be moved out of the way without clobbering an existing 
      # backup file.
      boto_config_from_env = os.environ.get('BOTO_CONFIG', None)
      if boto_config_from_env:
        default_config_path = boto_config_from_env
      else:
        default_config_path = os.path.expanduser(os.path.join('~', '.boto'))
      if not os.path.exists(default_config_path):
        output_file_name = default_config_path
        default_config_path_bak = None
      else:
        default_config_path_bak = default_config_path + '.bak'
        if os.path.exists(default_config_path_bak):
          raise CommandException('Cannot back up existing config '
              'file "%s": backup file exists ("%s").'
              % (default_config_path, default_config_path_bak))
        else:
          try:
            sys.stderr.write(
                'Backing up existing config file "%s" to "%s"...\n'
                % (default_config_path, default_config_path_bak))
            os.rename(default_config_path, default_config_path_bak)
          except e:
            raise CommandException('Failed to back up existing config '
                'file ("%s" -> "%s"): %s.'
                % (default_config_path, default_config_path_bak, e))
          output_file_name = default_config_path

    if output_file_name == '-':
      output_file = sys.stdout
    else:
      output_file = self._OpenConfigFile(output_file_name)
      sys.stderr.write(
          'This script will create a boto config file at\n%s\ncontaining your '
          'credentials, based on your responses to the following questions.\n\n'
          % output_file_name)

    # Catch ^C so we can restore the backup.
    signal.signal(signal.SIGINT, cleanup_handler)
    try:
      self._WriteBotoConfigFile(output_file, use_oauth2=use_oauth2,
          launch_browser=launch_browser, oauth2_scopes=scopes)
    except Exception, e:
      user_aborted = isinstance(e, AbortException)
      if user_aborted:
        sys.stderr.write('\nCaught ^C; cleaning up\n')
      # If an error occurred during config file creation, remove the invalid
      # config file and restore the backup file.
      if output_file_name != '-':
        output_file.close()
        os.unlink(output_file_name)
        if default_config_path_bak:
          sys.stderr.write('Restoring previous backed up file (%s)\n' %
                           default_config_path_bak)
          os.rename(default_config_path_bak, output_file_name)
      raise

    if output_file_name != '-':
      output_file.close()
      sys.stderr.write(
          '\nBoto config file "%s" created.\nIf you need to use a proxy to '
          'use a proxy to access the Internet please see the instructions in '
          'that file.\n' % output_file_name)

    return 0

def cleanup_handler(signalnum, handler):
  raise AbortException('User interrupted config command')