#!/usr/bin/python
# Copyright 2016 The Tulsi Authors. 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.

"""Bridge between Xcode and Bazel for the "build" action.

NOTE: This script must be executed in the same directory as the Xcode project's
main group in order to generate correct debug symbols.
"""

import collections
import json
import os
import re
import shutil
import stat
import StringIO
import subprocess
import sys
import textwrap
import time
import zipfile

import bazel_build_events
import bazel_options
import tulsi_logging


# List of frameworks that Xcode injects into test host targets that should be
# re-signed when running the tests on devices.
XCODE_INJECTED_FRAMEWORKS = [
    'IDEBundleInjection',
    'XCTAutomationSupport',
    'XCTest',
]


def _PrintXcodeWarning(msg):
  sys.stdout.write(':: warning: %s\n' % msg)
  sys.stdout.flush()


def _PrintXcodeError(msg):
  sys.stderr.write(':: error: %s\n' % msg)
  sys.stderr.flush()


class Timer(object):
  """Simple profiler."""

  def __init__(self, action_name, action_id):
    """Creates a new Timer object.

    Args:
      action_name: A human-readable action name, shown in the build log.
      action_id: A machine-readable action identifier, can be used for metrics.

    Returns:
      A Timer instance.
    """
    self.action_name = action_name
    self.action_id = action_id
    self._start = None

  def Start(self):
    self._start = time.time()
    return self

  def End(self):
    end = time.time()
    seconds = end - self._start
    tulsi_logging.Logger().log_action(self.action_name, self.action_id, seconds)


class CodesignBundleAttributes(object):
  """Wrapper class for codesigning attributes of a signed bundle."""

  # List of codesigning attributes that this script requires.
  _ATTRIBUTES = ['Authority', 'Identifier', 'TeamIdentifier']

  def __init__(self, codesign_output):
    self.attributes = {}

    pending_attributes = list(self._ATTRIBUTES)
    for line in codesign_output.split('\n'):
      if not pending_attributes:
        break

      for attribute in pending_attributes:
        if line.startswith(attribute):
          value = line[len(attribute) + 1:]
          self.attributes[attribute] = value
          pending_attributes.remove(attribute)
          break

    for attribute in self._ATTRIBUTES:
      if attribute not in self.attributes:
        _PrintXcodeError(
            'Failed to extract %s from %s.\n' % (attribute, codesign_output))

  def Get(self, attribute):
    """Returns the value for the given attribute, or None if it wasn't found."""
    value = self.attributes.get(attribute)
    if attribute not in self._ATTRIBUTES:
      _PrintXcodeError(
          'Attribute %s not declared to be parsed. ' % attribute +
          'Available attributes are %s.\n' % self._ATTRIBUTES)
    return value


class _OptionsParser(object):
  """Handles parsing script options."""

  # Key for options that should be applied to all build configurations.
  ALL_CONFIGS = '__all__'

  # The build configurations handled by this parser.
  KNOWN_CONFIGS = ['Debug', 'Release', 'Fastbuild']

  def __init__(self, sdk_version, platform_name, arch, main_group_path):
    self.targets = []
    self.startup_options = collections.defaultdict(list)
    self.build_options = collections.defaultdict(
        list,
        {
            _OptionsParser.ALL_CONFIGS: [
                '--verbose_failures',
                '--announce_rc',
            ],

            'Debug': [
                '--compilation_mode=dbg',
            ],

            'Release': [
                '--compilation_mode=opt',
                '--strip=always',
            ],

            'Fastbuild': [
                '--compilation_mode=fastbuild',
            ],
        })

    # Options specific to debugger integration in Xcode.
    xcode_version_major = int(os.environ['XCODE_VERSION_MAJOR'])
    if xcode_version_major < 800:
      xcode_lldb_options = [
          '--copt=-Xclang', '--copt=-fdebug-compilation-dir',
          '--copt=-Xclang', '--copt=%s' % main_group_path,
          '--objccopt=-Xclang', '--objccopt=-fdebug-compilation-dir',
          '--objccopt=-Xclang', '--objccopt=%s' % main_group_path,
      ]
      self.build_options['Debug'].extend(xcode_lldb_options)
      self.build_options['Release'].extend(xcode_lldb_options)

    self.sdk_version = sdk_version
    self.platform_name = platform_name

    if self.platform_name.startswith('watch'):
      config_platform = 'watchos'
    elif self.platform_name.startswith('iphone'):
      config_platform = 'ios'
    elif self.platform_name.startswith('appletv'):
      config_platform = 'tvos'
    else:
      self._WarnUnknownPlatform()
      config_platform = 'ios'
    self.build_options[_OptionsParser.ALL_CONFIGS].append(
        '--config=%s_%s' % (config_platform, arch))

    self.verbose = 0
    self.install_generated_artifacts = False
    self.bazel_bin_path = 'bazel-bin'
    self.bazel_executable = None

  @staticmethod
  def _UsageMessage():
    """Returns a usage message string."""
    usage = textwrap.dedent("""\
      Usage: %s <target> [<target2> ...] --bazel <bazel_binary_path> [options]

      Where options are:
        --verbose [-v]
            Increments the verbosity of the script by one level. This argument
            may be provided multiple times to enable additional output levels.

        --unpack_generated_ipa
            Unzips the contents of the IPA artifact generated by this build.

        --bazel_startup_options <option1> [<option2> ...] --
            Provides one or more Bazel startup options.

        --bazel_options <option1> [<option2> ...] --
            Provides one or more Bazel build options.

        --bazel_bin_path <path>
            Path at which Bazel-generated artifacts may be retrieved.
      """ % sys.argv[0])

    usage += '\n' + textwrap.fill(
        'Note that the --bazel_startup_options and --bazel_options options may '
        'include an optional configuration specifier in brackets to limit '
        'their contents to a given build configuration. Options provided with '
        'no configuration filter will apply to all configurations in addition '
        'to any configuration-specific options.', 120)

    usage += '\n' + textwrap.fill(
        'E.g., --bazel_options common --  --bazel_options[Release] release -- '
        'would result in "bazel build common release" in the "Release" '
        'configuration and "bazel build common" in all other configurations.',
        120)

    return usage

  def ParseOptions(self, args):
    """Parses arguments, returning (message, exit_code)."""

    bazel_executable_index = args.index('--bazel')

    self.targets = args[:bazel_executable_index]
    if not self.targets or len(args) < bazel_executable_index + 2:
      return (self._UsageMessage(), 10)
    self.bazel_executable = args[bazel_executable_index + 1]

    return self._ParseVariableOptions(args[bazel_executable_index + 2:])

  def GetStartupOptions(self, config):
    """Returns the full set of startup options for the given config."""
    return self._GetOptions(self.startup_options, config)

  def GetBuildOptions(self, config):
    """Returns the full set of build options for the given config."""
    options = self._GetOptions(self.build_options, config)

    version_string = self._GetXcodeVersionString()
    if version_string:
      self._AddDefaultOption(options, '--xcode_version', version_string)

    if self.sdk_version:
      if self.platform_name.startswith('watch'):
        self._AddDefaultOption(options,
                               '--watchos_sdk_version',
                               self.sdk_version)
      elif self.platform_name.startswith('iphone'):
        self._AddDefaultOption(options, '--ios_sdk_version', self.sdk_version)
      elif self.platform_name.startswith('appletv'):
        self._AddDefaultOption(options, '--tvos_sdk_version', self.sdk_version)
      else:
        self._WarnUnknownPlatform()
        self._AddDefaultOption(options, '--ios_sdk_version', self.sdk_version)
    return options

  @staticmethod
  def _AddDefaultOption(option_list, option, default_value):
    matching_options = [opt for opt in option_list if opt.startswith(option)]
    if matching_options:
      return option_list

    option_list.append('%s=%s' % (option, default_value))
    return option_list

  @staticmethod
  def _GetOptions(option_set, config):
    """Returns a flattened list from options_set for the given config."""
    options = list(option_set[_OptionsParser.ALL_CONFIGS])
    if config != _OptionsParser.ALL_CONFIGS:
      options.extend(option_set[config])
    return options

  def _WarnUnknownPlatform(self):
    sys.stdout.write('Warning: unknown platform "%s" will be treated as '
                     'iOS\n' % self.platform_name)
    sys.stdout.flush()

  def _ParseVariableOptions(self, args):
    """Parses flag-based args, returning (message, exit_code)."""

    verbose_re = re.compile('-(v+)$')

    while args:
      arg = args[0]
      args = args[1:]

      if arg == '--install_generated_artifacts':
        self.install_generated_artifacts = True

      elif arg.startswith('--bazel_startup_options'):
        config = self._ParseConfigFilter(arg)
        args, items, terminated = self._ParseDoubleDashDelimitedItems(args)
        if not terminated:
          return ('Missing "--" terminator while parsing %s' % arg, 2)
        duplicates = self._FindDuplicateOptions(self.startup_options,
                                                config,
                                                items)
        if duplicates:
          return (
              '%s items conflict with common options: %s' % (
                  arg, ','.join(duplicates)),
              2)
        self.startup_options[config].extend(items)

      elif arg.startswith('--bazel_options'):
        config = self._ParseConfigFilter(arg)
        args, items, terminated = self._ParseDoubleDashDelimitedItems(args)
        if not terminated:
          return ('Missing "--" terminator while parsing %s' % arg, 2)
        duplicates = self._FindDuplicateOptions(self.build_options,
                                                config,
                                                items)
        if duplicates:
          return (
              '%s items conflict with common options: %s' % (
                  arg, ','.join(duplicates)),
              2)
        self.build_options[config].extend(items)

      elif arg == '--bazel_bin_path':
        if not args:
          return ('Missing required parameter for %s' % arg, 2)
        self.bazel_bin_path = args[0]
        args = args[1:]

      elif arg == '--verbose':
        self.verbose += 1

      else:
        match = verbose_re.match(arg)
        if match:
          self.verbose += len(match.group(1))
        else:
          return ('Unknown option "%s"\n%s' % (arg, self._UsageMessage()), 1)

    return (None, 0)

  @staticmethod
  def _ParseConfigFilter(arg):
    match = re.search(r'\[([^\]]+)\]', arg)
    if not match:
      return _OptionsParser.ALL_CONFIGS
    return match.group(1)

  @staticmethod
  def _ConsumeArgumentForParam(param, args):
    if not args:
      return (None, 'Missing required parameter for "%s" option' % param)
    val = args[0]
    return (args[1:], val)

  @staticmethod
  def _ParseDoubleDashDelimitedItems(args):
    """Consumes options until -- is found."""
    options = []
    terminator_found = False

    opts = args
    while opts:
      opt = opts[0]
      opts = opts[1:]
      if opt == '--':
        terminator_found = True
        break
      options.append(opt)

    return opts, options, terminator_found

  @staticmethod
  def _FindDuplicateOptions(options_dict, config, new_options):
    """Returns a list of options appearing in both given option lists."""

    allowed_duplicates = [
        '--copt',
        '--config',
        '--define',
        '--objccopt',
    ]

    def ExtractOptionNames(opts):
      names = set()
      for opt in opts:
        split_opt = opt.split('=', 1)
        if split_opt[0] not in allowed_duplicates:
          names.add(split_opt[0])
      return names

    current_set = ExtractOptionNames(options_dict[config])
    new_set = ExtractOptionNames(new_options)
    conflicts = current_set.intersection(new_set)

    if config != _OptionsParser.ALL_CONFIGS:
      current_set = ExtractOptionNames(options_dict[_OptionsParser.ALL_CONFIGS])
      conflicts = conflicts.union(current_set.intersection(new_set))
    return conflicts

  @staticmethod
  def _GetXcodeVersionString():
    """Returns Xcode version info from the environment as a string."""
    reported_version = os.environ['XCODE_VERSION_ACTUAL']
    match = re.match(r'(\d{2})(\d)(\d)$', reported_version)
    if not match:
      sys.stdout.write('Warning: Failed to extract Xcode version from %s\n' % (
          reported_version))
      sys.stdout.flush()
      return None
    major_version = int(match.group(1))
    minor_version = int(match.group(2))
    fix_version = int(match.group(3))
    fix_version_string = ''
    if fix_version:
      fix_version_string = '.%d' % fix_version
    return '%d.%d%s' % (major_version, minor_version, fix_version_string)


class BazelBuildBridge(object):
  """Handles invoking Bazel and unpacking generated binaries."""

  BUILD_EVENTS_FILE = 'build_events.json'

  def __init__(self):
    self.verbose = 0
    self.build_path = None
    self.bazel_bin_path = None
    # The actual path to the Bazel output directory (not a symlink)
    self.real_bazel_bin_path = None
    # The path to the Bazel's sandbox source root.
    self.bazel_build_workspace_root = None
    self.bazel_genfiles_path = None
    self.bazel_symlink_prefix = None
    self.codesign_attributes = {}

    # Certain potentially expensive patchups need to be made for non-Xcode IDE
    # integrations. There isn't a fool-proof way of determining if the script is
    # being used with Xcode or not, but searching the CODESIGNING_FOLDER_PATH
    # env var for "/Xcode/" should catch the majority of use-cases.
    self.codesigning_folder_path = os.environ['CODESIGNING_FOLDER_PATH']
    self.likely_xcode = self.codesigning_folder_path.find('/Xcode/') != -1

    self.xcode_action = os.environ['ACTION']  # The Xcode build action.
    # When invoked as an external build system script, Xcode will set ACTION to
    # an empty string.
    if not self.xcode_action:
      self.xcode_action = 'build'

    self.generate_dsym = os.environ.get('TULSI_USE_DSYM', 'NO') == 'YES'
    self.use_bep = os.environ.get('TULSI_USE_BEP', 'YES') == 'YES'

    # Target architecture.  Must be defined for correct setting of
    # the --config flag
    self.arch = os.environ.get('CURRENT_ARCH')
    if not self.arch:
      _PrintXcodeError('Tulsi requires env variable CURRENT_ARCH to be '
                       'set.  Please file a bug against Tulsi.')
      sys.exit(1)

    # Bazel's notion of the type of artifact being generated.
    self.bazel_target_type = os.environ.get('BAZEL_TARGET_TYPE')
    # Path into which generated artifacts should be copied.
    self.built_products_dir = os.environ['BUILT_PRODUCTS_DIR']
    # Whether or not code coverage information should be generated.
    self.code_coverage_enabled = (
        os.environ.get('CLANG_COVERAGE_MAPPING') == 'YES')
    # Path where Xcode expects generated sources to be placed.
    self.derived_sources_folder_path = os.environ.get('DERIVED_SOURCES_DIR')
    # Full name of the target artifact (e.g., "MyApp.app" or "Test.xctest").
    self.full_product_name = os.environ['FULL_PRODUCT_NAME']
    # Target SDK version.
    self.sdk_version = os.environ.get('SDK_VERSION')
    # TEST_HOST for unit tests.
    self.test_host_binary = os.environ.get('TEST_HOST')
    # Whether this target is a test or not.
    self.is_test = os.environ.get('WRAPPER_EXTENSION') == 'xctest'
    # UTI type of the target.
    self.package_type = os.environ.get('PACKAGE_TYPE')
    # Target platform.
    self.platform_name = os.environ['PLATFORM_NAME']
    # Type of the target artifact.
    self.product_type = os.environ['PRODUCT_TYPE']
    # Path to the parent of the xcodeproj bundle.
    self.project_dir = os.environ['PROJECT_DIR']
    # Path to the xcodeproj bundle.
    self.project_file_path = os.environ['PROJECT_FILE_PATH']
    # Path to the parent of the Xcode project's mainGroup.
    self.source_root = os.environ['SOURCE_ROOT']
    # Path to the directory containing the WORKSPACE file.
    self.workspace_root = os.path.abspath(os.environ['TULSI_WR'])
    # Set to the name of the generated bundle for bundle-type targets, None for
    # single file targets (like static libraries).
    self.wrapper_name = os.environ.get('WRAPPER_NAME')
    self.wrapper_suffix = os.environ.get('WRAPPER_SUFFIX', '')
    self.xcode_version_major = int(os.environ['XCODE_VERSION_MAJOR'])
    self.xcode_version_minor = int(os.environ['XCODE_VERSION_MINOR'])

    # Path where Xcode expects the artifacts to be written to. This is not the
    # codesigning_path as device vs simulator builds have different signing
    # requirements, so Xcode expects different things to be signed. This is
    # mostly apparent on XCUITests where simulator builds set the codesigning
    # path to be the .xctest bundle, but for device builds it is actually the
    # UI runner app (since it needs to be codesigned to run on the device.) The
    # contents folder path is a stable path on where to put the expected
    # artifacts. For static libraries (objc_library, swift_library),
    # CONTENTS_FOLDER_PATH does not exist, but the location where Xcode expects
    # the archive coincides with the TARGET_BUILD_DIR, so using an empty
    # default for CONTENTS_FOLDER_PATH supports both bundle and single artifact
    # outputs.
    # TODO(b/35811023): Check these paths are still valid.
    self.content_folder_path = os.path.join(
        os.environ['TARGET_BUILD_DIR'],
        os.environ.get('CONTENTS_FOLDER_PATH', ''))

    # For macOS applications and extensions, Xcode includes the Contents/ at
    # the end, which we don't want.
    if (self.bazel_target_type == 'macos_application'
        or self.bazel_target_type == 'macos_extension'):
      head, tail = os.path.split(self.content_folder_path)
      if tail == 'Contents':
        self.content_folder_path = head

    # Path to where Xcode expects the binary to be placed.
    self.binary_path = os.path.join(
        os.environ['TARGET_BUILD_DIR'], os.environ['EXECUTABLE_PATH'])

    # Path to the Build Events JSON file.
    self.build_events_file_path = os.path.join(
        self.project_file_path,
        '.tulsi',
        BazelBuildBridge.BUILD_EVENTS_FILE)

    self.is_simulator = self.platform_name.endswith('simulator')
    # Check to see if code signing actions should be skipped or not.
    if self.is_simulator:
      self.codesigning_allowed = False
    else:
      self.codesigning_allowed = os.environ.get('CODE_SIGNING_ALLOWED') == 'YES'

    self.post_processor_binary = os.path.join(self.project_file_path,
                                              '.tulsi',
                                              'Utils',
                                              'post_processor')
    if self.codesigning_allowed:
      self.runner_entitlements_template = os.path.join(self.project_file_path,
                                                       '.tulsi',
                                                       'Resources',
                                                       'XCTRunner.entitlements')

    self.main_group_path = os.getcwd()

  def Run(self, args):
    """Executes a Bazel build based on the environment and given arguments."""
    if self.xcode_action != 'build':
      sys.stderr.write('Xcode action is %s, ignoring.' % self.xcode_action)
      return 0

    parser = _OptionsParser(self.sdk_version,
                            self.platform_name,
                            self.arch,
                            self.main_group_path)
    timer = Timer('Parsing options', 'parsing_options').Start()
    message, exit_code = parser.ParseOptions(args[1:])
    timer.End()
    if exit_code:
      _PrintXcodeError('Option parsing failed: %s' % message)
      return exit_code

    self.verbose = parser.verbose
    self.bazel_bin_path = os.path.abspath(parser.bazel_bin_path)
    # bazel_bin_path is assumed to always end in "-bin".
    self.bazel_symlink_prefix = self.bazel_bin_path[:-3]
    self.bazel_genfiles_path = self.bazel_symlink_prefix + 'genfiles'

    self.build_path = os.path.join(self.bazel_bin_path,
                                   os.environ.get('TULSI_BUILD_PATH', ''))
    (command, retval) = self._BuildBazelCommand(parser)
    if retval:
      return retval

    timer = Timer('Running Bazel', 'running_bazel').Start()
    exit_code, outputs = self._RunBazelAndPatchOutput(command)
    timer.End()
    if exit_code:
      _PrintXcodeError('Bazel build failed.')
      return exit_code

    exit_code = self._EnsureBazelBinIsValid()
    if exit_code:
      _PrintXcodeError('Failed to ensure existence of bazel-bin directory.')
      return exit_code

    # This needs to run after `bazel build`, since it depends on the Bazel
    # workspace directory
    exit_code = self._LinkTulsiWorkspace()
    if exit_code:
      return exit_code

    if parser.install_generated_artifacts:
      timer = Timer('Installing artifacts', 'installing_artifacts').Start()
      exit_code = self._InstallArtifact(outputs)
      timer.End()
      if exit_code:
        return exit_code

      timer = Timer('Installing generated headers',
                    'installing_generated_headers').Start()
      exit_code = self._InstallGeneratedHeaders(outputs)
      timer.End()
      if exit_code:
        return exit_code

      if self.generate_dsym:
        timer = Timer('Installing DSYM bundles', 'installing_dsym').Start()
        exit_code, dsym_path = self._InstallDSYMBundles(self.built_products_dir)
        timer.End()
        if exit_code:
          return exit_code
        if dsym_path:
          timer = Timer('Patching DSYM source file paths',
                        'patching_dsym').Start()
          exit_code = self._PatchdSYMPaths(dsym_path)
          timer.End()
          if exit_code:
            return exit_code

      # Starting with Xcode 7.3, XCTests inject several supporting frameworks
      # into the test host that need to be signed with the same identity as
      # the host itself.
      if (self.is_test and self.xcode_version_minor >= 730 and
          self.codesigning_allowed):
        exit_code = self._ResignTestArtifacts()
        if exit_code:
          return exit_code

    # Starting with Xcode 8, .lldbinit files are honored during Xcode debugging
    # sessions. This allows use of the target.source-map field to remap the
    # debug symbol paths encoded in the binary to the paths expected by Xcode.
    # In cases where a dSYM bundle was produced, the post_processor will have
    # already corrected the paths and use of target.source-map is redundant (and
    # appears to trigger actual problems in Xcode 8.1 betas).
    if self.xcode_version_major >= 800:
      timer = Timer('Updating .lldbinit', 'updating_lldbinit').Start()
      exit_code = self._UpdateLLDBInit(self.generate_dsym)
      timer.End()
      if exit_code:
        _PrintXcodeWarning('Updating .lldbinit action failed with code %d' %
                           exit_code)

    if self.code_coverage_enabled:
      timer = Timer('Patching LLVM covmap', 'patching_llvm_covmap').Start()
      exit_code = self._PatchLLVMCovmapPaths()
      timer.End()
      if exit_code:
        _PrintXcodeWarning('Patch LLVM covmap action failed with code %d' %
                           exit_code)
    return 0

  def _BuildBazelCommand(self, options):
    """Builds up a commandline string suitable for running Bazel."""
    bazel_command = [options.bazel_executable]

    configuration = os.environ['CONFIGURATION']
    # Treat the special testrunner build config as a Debug compile.
    test_runner_config_prefix = '__TulsiTestRunner_'
    if configuration.startswith(test_runner_config_prefix):
      configuration = configuration[len(test_runner_config_prefix):]
    elif os.environ.get('TULSI_TEST_RUNNER_ONLY') == 'YES':
      _PrintXcodeError('Building test targets with configuration "%s" is not '
                       'allowed. Please use the "Test" action or "Build for" > '
                       '"Testing" instead.' % configuration)
      return (None, 1)

    if configuration not in _OptionsParser.KNOWN_CONFIGS:
      _PrintXcodeError('Unknown build configuration "%s"' % configuration)
      return (None, 1)

    bazel_command.extend(options.GetStartupOptions(configuration))
    bazel_command.append('build')
    bazel_command.extend(options.GetBuildOptions(configuration))

    # Do not follow symlinks on __file__ in case this script is linked during
    # development.
    tulsi_package_dir = os.path.abspath(
        os.path.join(os.path.dirname(__file__), '..', 'Bazel'))

    if self.use_bep:
      bazel_command.append('--build_event_json_file=%s' %
                           self.build_events_file_path)
    else:
      bazel_command.append('--experimental_show_artifacts')

    bazel_command.extend([
        '--output_groups=tulsi-outputs,default',
        '--aspects', '@tulsi//tulsi:tulsi_aspects.bzl%tulsi_outputs_aspect',
        '--override_repository=tulsi=%s' % tulsi_package_dir,
        '--tool_tag=tulsi:bazel_build'])

    if self.code_coverage_enabled:
      self._PrintVerbose('Enabling code coverage information.')
      bazel_command.extend([
          '--collect_code_coverage',
          '--experimental_use_llvm_covmap'])

    if self.generate_dsym:
      bazel_command.append('--apple_generate_dsym')

    bazel_command.extend(options.targets)

    extra_options = bazel_options.BazelOptions(os.environ)
    bazel_command.extend(extra_options.bazel_feature_flags())

    return (bazel_command, 0)

  def _RunBazelAndPatchOutput(self, command):
    """Runs subprocess command, patching output as it's received."""
    self._PrintVerbose('Running "%s", patching output for main group path at '
                       '"%s" with project path at "%s".' %
                       (' '.join(command),
                        self.main_group_path,
                        self.project_dir))
    # Xcode translates anything that looks like ""<path>:<line>:" that is not
    # followed by the word "warning" into an error. Bazel warnings and debug
    # messages do not fit this scheme and must be patched here.
    bazel_warning_line_regex = re.compile(
        r'(?:DEBUG|WARNING): ([^:]+:\d+:(?:\d+:)?)\s+(.+)')

    def PatchBazelWarningStatements(output_line):
      match = bazel_warning_line_regex.match(output_line)
      if match:
        output_line = '%s warning: %s' % (match.group(1), match.group(2))
      return output_line

    def ExtractOutputs(output_line):
      if output_line.startswith('>>>') and output_line.endswith('.tulsiouts'):
        return output_line[3:]

    patch_xcode_parsable_line = PatchBazelWarningStatements
    if self.main_group_path != self.project_dir:
      # Match (likely) filename:line_number: lines.
      xcode_parsable_line_regex = re.compile(r'([^/][^:]+):\d+:')

      def PatchOutputLine(output_line):
        output_line = PatchBazelWarningStatements(output_line)
        if xcode_parsable_line_regex.match(output_line):
          output_line = '%s/%s' % (self.main_group_path, output_line)
        return output_line
      patch_xcode_parsable_line = PatchOutputLine

    def HandleOutput(output):
      for line in output.splitlines():
        line = patch_xcode_parsable_line(line) + '\n'
        sys.stdout.write(line)
        sys.stdout.flush()

    def WatcherUpdate(watcher):
      """Processes any new events in the given watcher.

      Args:
        watcher: a BazelBuildEventsWatcher object.

      Returns:
        A list of new tulsiout file names seen.
      """
      new_events = watcher.check_for_new_events()
      new_outputs = []
      for build_event in new_events:
        if build_event.stderr:
          HandleOutput(build_event.stderr)
        if build_event.stdout:
          HandleOutput(build_event.stdout)
        if build_event.files:
          outputs = [x for x in build_event.files if x.endswith('.tulsiouts')]
          new_outputs.extend(outputs)
      return new_outputs

    if self.use_bep:
      # Make sure the BEP JSON file exists and is empty. We do this to prevent
      # any sort of race between the watcher, bazel, and the old file contents.
      open(self.build_events_file_path, 'w').close()

      # Start Bazel without any extra files open besides /dev/null, which is
      # used to ignore the output.
      with open(os.devnull, 'w') as devnull:
        process = subprocess.Popen(command,
                                   stdout=devnull,
                                   stderr=subprocess.STDOUT)

      with open(self.build_events_file_path, 'r') as bep_file:
        watcher = bazel_build_events.BazelBuildEventsWatcher(bep_file,
                                                             _PrintXcodeWarning)
        output_locations = []
        while process.returncode is None:
          output_locations.extend(WatcherUpdate(watcher))
          time.sleep(0.1)
          process.poll()

        output_locations.extend(WatcherUpdate(watcher))

        if process.returncode == 0:
          if not output_locations:
            _PrintXcodeError('Unable to find location of the .tulsiouts file.'
                             'Please report this as a Tulsi bug, including the'
                             'contents of %s.' % self.build_events_file_path)
            return 1, output_locations
          if not watcher.is_build_complete():
            _PrintXcodeWarning('Unable to resolve all build events. Please'
                               'report this as a Tulsi bug, including the'
                               'contents of %s.' % self.build_events_file_path)

        return process.returncode, output_locations
    else:  # TODO(b/65198307): Remove this to complete swap to BEP.
      process = subprocess.Popen(command,
                                 stdout=subprocess.PIPE,
                                 stderr=subprocess.STDOUT,
                                 bufsize=1)
      output_locations = []
      linebuf = ''
      while process.returncode is None:
        for line in process.stdout.readline():
          # Occasionally Popen's line-buffering appears to break down. Not
          # entirely certain why this happens, but we use an accumulator to
          # try to deal with it.
          if not line.endswith('\n'):
            linebuf += line
            continue

          complete_line = linebuf + line
          # >>> marks the start of an aspect output location.
          # .tulsiouts files contin build output locations
          output_path = ExtractOutputs(complete_line.strip())
          if output_path:
            output_locations.append(output_path)
          else:
            line = patch_xcode_parsable_line(complete_line)
          linebuf = ''
          sys.stdout.write(line)
          sys.stdout.flush()
        process.poll()

      output, _ = process.communicate()
      output = linebuf + output

      for line in output.split('\n'):
        output_path = ExtractOutputs(line)
        if output_path:
          output_locations.append(output_path)
        else:
          line = patch_xcode_parsable_line(line)
        print line

      return process.returncode, output_locations

  def _EnsureBazelBinIsValid(self):
    """Ensures that the Bazel output path points at a real directory."""

    if not os.path.isdir(self.bazel_bin_path):
      _PrintXcodeWarning('Bazel "-bin" path at "%s" non-existent' %
                         (self.bazel_bin_path))
      return 0

    self.real_bazel_bin_path = (
        os.path.abspath(os.path.realpath(self.bazel_bin_path)))
    if not os.path.isdir(self.real_bazel_bin_path):
      try:
        os.makedirs(self.real_bazel_bin_path)
      except OSError as e:
        _PrintXcodeError('Failed to create Bazel binary dir at "%s". %s' %
                         (self.real_bazel_bin_path, e))
        return 20

    # The Bazel bin path will be of the form:
    #   <sandbox>/execroot/<workspace_path>/bazel-out/<arch>/bin
    # As the workspace root is user-configurable and could be set to
    # "bazel-out," the workspace path is obtained by slicing off the last
    # three components.
    path_components = self.real_bazel_bin_path.split(os.sep)
    if len(path_components) < 5:
      _PrintXcodeWarning('Failed to derive Bazel build root path from %r' %
                         self.real_bazel_bin_path)
    else:
      self.bazel_build_workspace_root = (
          os.sep + os.path.join(*path_components[:-3]))
    return 0

  def _InstallArtifact(self, outputs):
    """Installs Bazel-generated artifacts into the Xcode output directory."""
    xcode_artifact_path = self.content_folder_path

    if os.path.isdir(xcode_artifact_path):
      try:
        shutil.rmtree(xcode_artifact_path)
      except OSError as e:
        _PrintXcodeError('Failed to remove stale output directory ""%s". '
                         '%s' % (xcode_artifact_path, e))
        return 600
    elif os.path.isfile(xcode_artifact_path):
      try:
        os.remove(xcode_artifact_path)
      except OSError as e:
        _PrintXcodeError('Failed to remove stale output file ""%s". '
                         '%s' % (xcode_artifact_path, e))
        return 600

    try:
      output_data = json.load(open(outputs[0]))
    except (ValueError, IOError) as e:
      _PrintXcodeError('Failed to load output map ""%s". '
                       '%s' % (outputs[0], e))
      return 600

    if 'artifacts' not in output_data:
      _PrintXcodeError(
          'Failed to find an output artifact for target %s in output map %r' %
          (xcode_artifact_path, output_data))
      return 601

    primary_artifact = output_data['artifacts'][0]

    # The PRODUCT_NAME used by the Xcode project is not trustable as it may be
    # modified by the user and, more importantly, may have been modified by
    # Tulsi to disambiguate multiple targets with the same name.
    # To work around this, the product name is determined by dropping any
    # extension from the primary artifact.
    # TODO(abaire): Consider passing this value to the script explicitly.
    self.bazel_product_name = os.path.splitext(
        os.path.basename(primary_artifact))[0]

    if primary_artifact.endswith('.ipa') or primary_artifact.endswith('.zip'):
      bundle_name = output_data.get('bundle_name')
      exit_code = self._UnpackTarget(primary_artifact, xcode_artifact_path,
                                     bundle_name=bundle_name)
      if exit_code:
        return exit_code

      exit_code = self._RewriteInfoPlistIfNecessary(xcode_artifact_path)
      if exit_code:
        return exit_code
    elif os.path.isfile(primary_artifact):
      exit_code = self._CopyFile(os.path.basename(primary_artifact),
                                 primary_artifact,
                                 xcode_artifact_path)
      if exit_code:
        return exit_code
    else:
      self._CopyBundle(os.path.basename(primary_artifact),
                       primary_artifact,
                       xcode_artifact_path)

    return 0

  def _InstallGeneratedHeaders(self, output_files):
    """Installs Bazel-generated headers into tulsi-includes directory."""
    tulsi_root = os.path.join(self.bazel_build_workspace_root, 'tulsi-includes')

    if os.path.exists(tulsi_root):
      shutil.rmtree(tulsi_root)
    else:
      os.mkdir(tulsi_root)

    for f in output_files:
      data = json.load(open(f))
      if 'generated_sources' not in data:
        continue

      for gs in data['generated_sources']:
        real_path, link_path = gs
        src = os.path.join(self.bazel_build_workspace_root, real_path)

        # Bazel outputs are not guaranteed to be created if nothing references
        # them. This check skips the processing if an output was declared
        # but not created.
        if not os.path.exists(src):
          continue

        # The /x/x/ part is here to match the number of directory components
        # between tulsi root and bazel root. See tulsi_aspects.bzl for futher
        # explanation.
        dst = os.path.join(tulsi_root, 'x/x/', link_path)
        self._PrintVerbose('Symlinking %s to %s' % (src, dst), 2)

        dst_dir = os.path.split(dst)[0]
        if not os.path.exists(dst_dir):
          os.makedirs(dst_dir)

        # It's important to use lexists() here in case dst is a broken symlink
        # (in which case exists() would return False). For example, older
        # versions of this script did not check if src existed and could create
        # a symlink to an invalid path.
        if os.path.lexists(dst):
          os.unlink(dst)

        os.symlink(src, dst)

  def _CopyBundle(self, source_path, full_source_path, output_path):
    """Copies the given bundle to the given expected output path."""
    self._PrintVerbose('Copying %s to %s' % (source_path, output_path))
    try:
      shutil.copytree(full_source_path, output_path)
    except OSError as e:
      _PrintXcodeError('Copy failed. %s' % e)
      return 650
    return 0

  def _CopyFile(self, source_path, full_source_path, output_path):
    """Copies the given file to the given expected output path."""
    self._PrintVerbose('Copying %s to %s' % (source_path, output_path))
    output_path_dir = os.path.dirname(output_path)
    if not os.path.exists(output_path_dir):
      try:
        os.makedirs(output_path_dir)
      except OSError as e:
        _PrintXcodeError('Failed to create output directory ""%s". '
                         '%s' % (output_path_dir, e))
        return 650
    try:
      shutil.copy(full_source_path, output_path)
    except OSError as e:
      _PrintXcodeError('Copy failed. %s' % e)
      return 650
    return 0

  def _UnpackTarget(self, ipa_path, output_path, bundle_name=None):
    """Unpacks generated IPA into the given expected output path."""
    self._PrintVerbose('Unpacking %s to %s' % (ipa_path, output_path))

    if not os.path.isfile(ipa_path):
      _PrintXcodeError('Generated IPA not found at "%s"' % ipa_path)
      return 670

    # We need to handle IPAs (from the native rules) differently from ZIPs
    # (from the Skylark rules) because they output slightly different directory
    # structures.
    is_ipa = ipa_path.endswith('.ipa')

    if bundle_name:
      expected_bundle_name = bundle_name + self.wrapper_suffix
    else:
      # TODO(b/33050780): Remove this branch when native rules are removed.
      # With old native rules Tulsi expects the bundle within the IPA to be the
      # product name with the suffix expected by Xcode attached to it.
      expected_bundle_name = self.bazel_product_name + self.wrapper_suffix

    # The directory structure within the IPA is then determined based on Bazel's
    # package and/or product type.
    if is_ipa:
      if (self.package_type == 'com.apple.package-type.app-extension' or
          self.product_type == 'com.apple.product-type.application.watchapp'):
        expected_ipa_subpath = os.path.join('PlugIns', expected_bundle_name)
      elif self.product_type == 'com.apple.product-type.application.watchapp2':
        expected_ipa_subpath = os.path.join('Watch', expected_bundle_name)
      else:
        expected_ipa_subpath = os.path.join('Payload', expected_bundle_name)
    else:
      # If the artifact is a ZIP, assume that the bundle is the top-level
      # directory (this is the way in which Skylark rules package artifacts
      # that are not standalone IPAs).
      expected_ipa_subpath = expected_bundle_name

    with zipfile.ZipFile(ipa_path, 'r') as zf:
      for item in zf.infolist():
        filename = item.filename

        # Support directories do not seem to be needed by the debugger and are
        # skipped.
        basedir = filename.split(os.sep)[0]
        if basedir.endswith('Support') or basedir.endswith('Support2'):
          continue

        if len(filename) < len(expected_ipa_subpath):
          continue

        attributes = (item.external_attr >> 16) & 0777
        self._PrintVerbose('Extracting %s (%o)' % (filename, attributes),
                           level=1)

        if not filename.startswith(expected_ipa_subpath):
          # TODO(abaire): Make an error if Bazel modifies this behavior.
          _PrintXcodeWarning('Mismatched extraction path. IPA content at '
                             '"%s" expected to have subpath of "%s"' %
                             (filename, expected_ipa_subpath))

        dir_components = self._SplitPathComponents(filename)

        # Get the file's path, ignoring the payload components if the archive
        # is an IPA.
        if is_ipa:
          subpath = os.path.join(*dir_components[2:])
        else:
          subpath = os.path.join(*dir_components[1:])
        target_path = os.path.join(output_path, subpath)

        # Ensure the target directory exists.
        try:
          target_dir = os.path.dirname(target_path)
          if not os.path.isdir(target_dir):
            os.makedirs(target_dir)
        except OSError as e:
          _PrintXcodeError(
              'Failed to create target path "%s" during extraction. %s' % (
                  target_path, e))
          return 671

        # If the archive item looks like a file, extract it.
        if not filename.endswith(os.sep):
          with zf.open(item) as src, file(target_path, 'wb') as dst:
            shutil.copyfileobj(src, dst)

        # Patch up the extracted file's attributes to match the zip content.
        if attributes:
          os.chmod(target_path, attributes)

    return 0

  # TODO(abaire): Delete this function when the bundling rules use plutil to
  # write the final binary plist output.
  def _RewriteInfoPlistIfNecessary(self, output_path):
    """Runs plutil to rewrite the Info.plist file to support various tools."""

    # Specifically, AppCode 2016 fails to parse the Info.plist generated by
    # Bazel. Doing a plutil to convert it to INFOPLIST_OUTPUT_FORMAT (which
    # should be a nop since the env var is typically "binary" and the plist
    # should already be binary) fixes the issue. This fix is expensive (at
    # least two external tool invokes) so it's skipped in the Xcode case.
    if self.likely_xcode:
      return 0

    infoplist_path = os.environ.get('INFOPLIST_PATH', None)
    if not infoplist_path:
      return 0

    bundle_parent, bundle_name = os.path.split(output_path)
    if not infoplist_path.startswith(bundle_name):
      _PrintXcodeWarning('Mismatch in bundle output name ("%s") and '
                         'Info.plist subpath ("%s"). Info.plist file will not '
                         'be modified and may lead to a failure.' % (
                             output_path, infoplist_path))
      return 0

    infoplist_full_path = os.path.join(bundle_parent, infoplist_path)

    # Bail out gracefully if the plist is read-only, indicating that it was
    # already processed by plutil.
    if os.stat(infoplist_full_path)[stat.ST_MODE] & stat.S_IWUSR == 0:
      return 0

    # Note that the tool expects "<type>1", e.g., "binary1" but the env var is
    # of the form "<type>".
    fmt = os.environ.get('INFOPLIST_OUTPUT_FORMAT', 'binary') + '1'
    timer = Timer('\tUpdating plist', 'updating_plist').Start()
    command = ['xcrun',
               'plutil',
               '-convert',
               fmt,
               infoplist_full_path]
    process = subprocess.Popen(command,
                               stdout=subprocess.PIPE,
                               stderr=subprocess.STDOUT)
    stdout, _ = process.communicate()
    timer.End()
    if process.returncode:
      _PrintXcodeWarning('Plist conversion command %r failed. %s' % (
          command, stdout))
      return 100 + process.returncode

    signing_identity = self._ExtractSigningIdentity(output_path)
    if not signing_identity:
      return 800
    return self._ResignBundle(output_path, signing_identity)

  def _InstallDSYMBundles(self, output_dir):
    """Copies any generated dSYM bundles to the given directory."""
    # TODO(abaire): Support mapping the dSYM generated for an objc_binary.
    # ios_application's will have a dSYM generated with the linked obj_binary's
    # filename, so the target_dsym will never actually match.
    target_dsym = os.environ.get('DWARF_DSYM_FILE_NAME')
    if not target_dsym:
      return 0, None

    input_dsym_full_path = os.path.join(self.build_path, target_dsym)
    # ios_extension incorrectly names dSYM bundles as .app while
    # skylark_ios_extension correctly names them with .appex. To support both
    # rules, try and locate either name.
    if not os.path.isdir(input_dsym_full_path):
      target_dsym = target_dsym.replace('.appex', '.app')
      input_dsym_full_path = os.path.join(self.build_path, target_dsym)

    output_full_path = os.path.join(output_dir, target_dsym)
    if os.path.isdir(output_full_path):
      try:
        shutil.rmtree(output_full_path)
      except OSError as e:
        _PrintXcodeError('Failed to remove stale output dSYM bundle ""%s". '
                         '%s' % (output_full_path, e))
        return 700, None

    if os.path.isdir(input_dsym_full_path):
      exit_code = self._CopyBundle(target_dsym,
                                   input_dsym_full_path,
                                   output_full_path)
      return exit_code, output_full_path

    if 'BAZEL_BINARY_DSYM' in os.environ:
      # TODO(abaire): Remove this hack once Bazel generates dSYMs for
      #               ios_application/etc... bundles instead of their
      #               contained binaries.
      bazel_dsym_path = os.environ['BAZEL_BINARY_DSYM']
      build_path_prefix = os.environ.get('TULSI_BUILD_PATH', '')
      if bazel_dsym_path.startswith(build_path_prefix):
        bazel_dsym_path = bazel_dsym_path[len(build_path_prefix) + 1:]
      input_dsym_full_path = os.path.join(self.build_path, bazel_dsym_path)
      if os.path.isdir(input_dsym_full_path):
        exit_code = self._CopyBundle(bazel_dsym_path,
                                     input_dsym_full_path,
                                     output_full_path)
        return exit_code, output_full_path

    return 0, None

  def _ResignBundle(self, bundle_path, signing_identity, entitlements=None):
    """Re-signs the bundle with the given signing identity and entitlements."""
    if not self.codesigning_allowed:
      return 0

    timer = Timer('\tSigning ' + bundle_path, 'signing_bundle').Start()
    command = [
        'xcrun',
        'codesign',
        '-f',
        '--timestamp=none',
        '-s',
        signing_identity,
    ]

    if entitlements:
      command.extend(['--entitlements', entitlements])
    else:
      command.append('--preserve-metadata=entitlements')

    command.append(bundle_path)

    returncode, output = self._RunSubprocess(command)
    timer.End()
    if returncode:
      _PrintXcodeError('Re-sign command %r failed. %s' % (command, output))
      return 800 + returncode
    return 0

  def _ResignTestArtifacts(self):
    """Resign test related artifacts that Xcode injected into the outputs."""
    if not self.is_test:
      return 0
    # Extract the signing identity from the bundle at the expected output path
    # since that's where the signed bundle from bazel was placed.
    signing_identity = self._ExtractSigningIdentity(self.content_folder_path)
    if not signing_identity:
      return 800

    exit_code = 0
    timer = Timer('Re-signing injected test host artifacts',
                  'resigning_test_host').Start()

    if self.test_host_binary:
      # For Unit tests, we need to resign the frameworks that Xcode injected
      # into the test host bundle.
      test_host_bundle = os.path.dirname(self.test_host_binary)
      exit_code = self._ResignXcodeTestFrameworks(
          test_host_bundle, signing_identity)
    else:
      # For UI tests, we need to resign the UI test runner app and the
      # frameworks that Xcode injected into the runner app. The UI Runner app
      # also needs to be signed with entitlements.
      exit_code = self._ResignXcodeTestFrameworks(
          self.codesigning_folder_path, signing_identity)
      if exit_code == 0:
        entitlements_path = self._InstantiateUIRunnerEntitlements()
        if entitlements_path:
          exit_code = self._ResignBundle(
              self.codesigning_folder_path,
              signing_identity,
              entitlements_path)
        else:
          _PrintXcodeError('Could not instantiate UI runner entitlements.')
          exit_code = 800

    timer.End()
    return exit_code

  def _ResignXcodeTestFrameworks(self, bundle, signing_identity):
    """Re-signs the support frameworks injected by Xcode in the given bundle."""
    if not self.codesigning_allowed:
      return 0

    for framework in XCODE_INJECTED_FRAMEWORKS:
      framework_path = os.path.join(
          bundle, 'Frameworks', '%s.framework' % framework)
      if os.path.isdir(framework_path):
        exit_code = self._ResignBundle(framework_path, signing_identity)
        if exit_code != 0:
          return exit_code
    return 0

  def _InstantiateUIRunnerEntitlements(self):
    """Substitute team and bundle identifiers into UI runner entitlements.

    This method throws an IOError exception if the template wasn't found in
    its expected location, or an OSError if the expected output folder could
    not be created.

    Returns:
      The path to where the entitlements file was generated.
    """
    if not self.codesigning_allowed:
      return None
    if not os.path.exists(self.derived_sources_folder_path):
      os.makedirs(self.derived_sources_folder_path)

    output_file = os.path.join(
        self.derived_sources_folder_path,
        self.bazel_product_name + '_UIRunner.entitlements')
    if os.path.exists(output_file):
      os.remove(output_file)

    with open(self.runner_entitlements_template, 'r') as template:
      contents = template.read()
      contents = contents.replace(
          '$(TeamIdentifier)',
          self._ExtractSigningTeamIdentifier(self.content_folder_path))
      contents = contents.replace(
          '$(BundleIdentifier)',
          self._ExtractSigningBundleIdentifier(self.content_folder_path))
      with open(output_file, 'w') as output:
        output.write(contents)
    return output_file

  def _ExtractSigningIdentity(self, signed_bundle):
    """Returns the identity used to sign the given bundle path."""
    return self._ExtractSigningAttribute(signed_bundle, 'Authority')

  def _ExtractSigningTeamIdentifier(self, signed_bundle):
    """Returns the team identifier used to sign the given bundle path."""
    return self._ExtractSigningAttribute(signed_bundle, 'TeamIdentifier')

  def _ExtractSigningBundleIdentifier(self, signed_bundle):
    """Returns the bundle identifier used to sign the given bundle path."""
    return self._ExtractSigningAttribute(signed_bundle, 'Identifier')

  def _ExtractSigningAttribute(self, signed_bundle, attribute):
    """Returns the attribute used to sign the given bundle path."""
    if not self.codesigning_allowed:
      return '<CODE_SIGNING_ALLOWED=NO>'

    cached = self.codesign_attributes.get(signed_bundle)
    if cached:
      return cached.Get(attribute)

    timer = Timer('\tExtracting signature for ' + signed_bundle,
                  'extracting_signature').Start()
    output = subprocess.check_output(['xcrun',
                                      'codesign',
                                      '-dvv',
                                      signed_bundle],
                                     stderr=subprocess.STDOUT)
    timer.End()

    bundle_attributes = CodesignBundleAttributes(output)
    self.codesign_attributes[signed_bundle] = bundle_attributes
    return bundle_attributes.Get(attribute)

  _TULSI_LLDBINIT_BLOCK_START = '# <TULSI> LLDB bridge [:\n'
  _TULSI_LLDBINIT_BLOCK_END = '# ]: <TULSI> LLDB bridge\n'
  _TULSI_LLDBINIT_FILE = os.path.expanduser('~/.lldbinit-tulsiproj')
  _TULSI_LLDBINIT_EPILOGUE_FILE = (
      os.path.expanduser('~/.lldbinit-tulsiproj-epilogue'))

  def _ExtractLLDBInitContent(self, lldbinit_path):
    """Extracts the non-Tulsi content of the given lldbinit file."""
    if not os.path.isfile(lldbinit_path):
      return []
    content = []
    with open(lldbinit_path) as f:
      ignoring = False
      for line in f:
        if ignoring:
          if line == self._TULSI_LLDBINIT_BLOCK_END:
            ignoring = False
          continue
        if line == self._TULSI_LLDBINIT_BLOCK_START:
          ignoring = True
          continue
        content.append(line)
    return content

  def _LinkTulsiLLDBInit(self):
    """Adds a reference to ~/.lldbinit-tulsi to the primary lldbinit file.

    Xcode 8+ caches the contents of ~/.lldbinit-Xcode on startup. To get around
    this, an external reference to ~/.lldbinit-tulsi is added, causing LLDB
    itself to load the possibly modified contents on each session.
    """

    lldbinit_path = os.path.expanduser('~/.lldbinit-Xcode')
    if not os.path.isfile(lldbinit_path):
      lldbinit_path = os.path.expanduser('~/.lldbinit')

    content = self._ExtractLLDBInitContent(lldbinit_path)
    out = StringIO.StringIO()
    for line in content:
      out.write(line)

    out.write(self._TULSI_LLDBINIT_BLOCK_START)
    out.write('# This was autogenerated by Tulsi in order to influence LLDB '
              'source-maps at build time.\n')
    out.write('command source %s\n' % self._TULSI_LLDBINIT_FILE)
    out.write(self._TULSI_LLDBINIT_BLOCK_END)

    with open(lldbinit_path, 'w') as outfile:
      out.seek(0)
      # Negative length to make copyfileobj write the whole file at once.
      shutil.copyfileobj(out, outfile, -1)

  def _LinkTulsiLLDBInitEpilogue(self, outfile):
    """Adds a reference to ~/.lldbinit-tulsi-epilogue if it exists.

    This file can be used to append more LLDB commands right after
    .lldbinit-tulsi is sourced.

    Useful for extending or resetting LLDB settings that Tulsi may have set
    automatically

    Args:
      outfile: a file-type object.

    Returns:
      None
    """
    if os.path.isfile(self._TULSI_LLDBINIT_EPILOGUE_FILE):
      outfile.write('command source %s\n' % self._TULSI_LLDBINIT_EPILOGUE_FILE)

  def _UpdateLLDBInit(self, clear_source_map=False):
    """Updates ~/.lldbinit-tulsi to enable debugging of Bazel binaries."""

    # Apple Watch app binaries do not contain any sources.
    if self.product_type == 'com.apple.product-type.application.watchapp2':
      return 0

    self._LinkTulsiLLDBInit()

    with open(self._TULSI_LLDBINIT_FILE, 'w') as out:
      out.write('# This file is autogenerated by Tulsi and should not be '
                'edited.\n')

      if clear_source_map:
        out.write('settings clear target.source-map\n')
        self._LinkTulsiLLDBInitEpilogue(out)
        return 0

      timer = Timer(
          '\tExtracting source paths for ' + self.full_product_name,
          'extracting_source_paths').Start()

      source_paths = self._ExtractTargetSourcePaths()
      timer.End()

      if source_paths is None:
        _PrintXcodeWarning('Failed to extract source paths for LLDB. '
                           'File-based breakpoints will likely not work.')
        return 900

      if not source_paths:
        _PrintXcodeWarning('Extracted 0 source paths from %r. File-based '
                           'breakpoints may not work. Please report as a bug.' %
                           self.full_product_name)
        return 0

      out.write('# This maps file paths used by Bazel to those used by %r.\n' %
                os.path.basename(self.project_file_path))
      workspace_root_parent = os.path.dirname(self.workspace_root)

      source_maps = []
      for p, symlink in source_paths:
        if symlink:
          local_path = os.path.join(workspace_root_parent, symlink)
        else:
          local_path = workspace_root_parent
        source_maps.append('"%s" "%s"' % (p, local_path))
      source_maps.sort(reverse=True)

      out.write('settings set target.source-map %s\n' % ' '.join(source_maps))
      self._LinkTulsiLLDBInitEpilogue(out)

    return 0

  def _PatchLLVMCovmapPaths(self):
    """Invokes post_processor to fix source paths in LLVM coverage maps."""
    if not self.bazel_build_workspace_root:
      _PrintXcodeWarning('No Bazel sandbox root was detected, unable to '
                         'determine coverage paths to patch. Code coverage '
                         'will probably fail.')
      return 0

    if not os.path.isfile(self.binary_path):
      return 0

    self._PrintVerbose('Patching %r -> %r' % (self.bazel_build_workspace_root,
                                              self.workspace_root), 1)
    args = [
        self.post_processor_binary,
        '-c',
    ]
    if self.verbose > 1:
      args.append('-v')
    args.extend([
        self.binary_path,
        self.bazel_build_workspace_root,
        self.workspace_root
    ])
    returncode, output = self._RunSubprocess(args)
    if returncode:
      _PrintXcodeWarning('Coverage map patching failed on binary %r (%d). Code '
                         'coverage will probably fail.' %
                         (self.binary_path, returncode))
      _PrintXcodeWarning('Output: %s' % output or '<no output>')
      return 0

    return 0

  def _PatchdSYMPaths(self, dsym_bundle_path):
    """Invokes post_processor to fix source paths in dSYM DWARF data."""
    if not self.bazel_build_workspace_root:
      _PrintXcodeWarning('No Bazel sandbox root was detected, unable to '
                         'determine DWARF paths to patch. Debugging will '
                         'probably fail.')
      return 0

    dwarf_subpath = os.path.join(dsym_bundle_path,
                                 'Contents',
                                 'Resources',
                                 'DWARF')
    binaries = [os.path.join(dwarf_subpath, b)
                for b in os.listdir(dwarf_subpath)]
    for binary_path in binaries:
      os.chmod(binary_path, 0755)

    args = [self.post_processor_binary, '-d']
    if self.verbose > 1:
      args.append('-v')
    args.extend(binaries)
    args.extend([self.bazel_build_workspace_root, self.workspace_root])

    self._PrintVerbose('Patching %r -> %r' % (self.bazel_build_workspace_root,
                                              self.workspace_root), 1)
    returncode, output = self._RunSubprocess(args)
    if returncode:
      _PrintXcodeWarning('DWARF path patching failed on dSYM %r (%d). '
                         'Breakpoints and other debugging actions will '
                         'probably fail.' % (dsym_bundle_path, returncode))
      _PrintXcodeWarning('Output: %s' % output or '<no output>')
      return 0

    return 0

  def _ExtractTargetSourcePaths(self):
    """Extracts set((source paths, symlink)) from the target's debug symbols.

    Returns:
      None: if an error occurred.
      set(str): containing tuples of unique source paths in the target binary
                associated with the symlink used by Tulsi generated Xcode
                projects if applicable. For example, a source path to a
                /genfiles/ directory will be associated with "bazel-genfiles".
                Paths will only be returned if they're available on the
                local filesystem.
    """
    if not os.path.isfile(self.binary_path):
      _PrintXcodeWarning('No binary at expected path %r' % self.binary_path)
      return None

    returncode, output = self._RunSubprocess([
        'xcrun',
        'dsymutil',
        '-s',
        self.binary_path
    ])
    if returncode:
      _PrintXcodeWarning('dsymutil returned %d while examining symtable for %r'
                         % (returncode, self.binary_path))
      return None

    # Symbol table lines of interest are of the form:
    #  [index] n_strx (N_SO ) n_sect n_desc n_value 'source_path'
    # where source_path is an absolute path (rather than a filename). There are
    # several paths of interest:
    # The path up to "/bin/" is mapped to bazel-bin.
    # The path up to "/genfiles/" is mapped to bazel-genfiles.
    # The path up to "execroot" covers any other cases.
    source_path_re = re.compile(
        r'\[\s*\d+\]\s+.+?\(N_SO\s*\)\s+.+?\'(/.+?/execroot)/(.*?)\'\s*$')
    source_path_prefixes = set()

    # TODO(b/35624202): Remove when target.source_map problem is resolved.
    paths_not_found = set()

    bazel_out_symlink = self.bazel_symlink_prefix + 'out'
    for line in output.split('\n'):
      match = source_path_re.match(line)
      if not match:
        continue
      basepath = match.group(1)
      if not os.path.exists(basepath):
        # TODO(b/35624202): Remove when target.source_map problem is resolved.
        if basepath not in paths_not_found:
          paths_not_found.add(basepath)
          self._PrintPathNotFoundWarning(basepath)
        continue
      # Subpaths of interest will be of the form
      # <workspace>/bazel-out/<arch>-<mode>/<interesting_bit>/...
      subpath = match.group(2)
      components = subpath.split(os.sep, 5)
      if len(components) >= 4 and components[1] == bazel_out_symlink:
        symlink_component = components[3]
        match_path = os.path.join(basepath, *components[:4])
        if not os.path.exists(match_path):
          # TODO(b/35624202): Remove when target.source_map problem is resolved.
          if match_path not in paths_not_found:
            paths_not_found.add(match_path)
            self._PrintPathNotFoundWarning(match_path)
          continue
        if symlink_component == 'bin':
          source_path_prefixes.add((match_path, self.bazel_bin_path))
          continue
        if symlink_component == 'genfiles':
          source_path_prefixes.add((match_path, self.bazel_genfiles_path))
          continue

      source_path_prefixes.add((basepath, None))

    return source_path_prefixes

  def _LinkTulsiWorkspace(self):
    """Links the Bazel Workspace to the Tulsi Workspace (`tulsi-workspace`)."""
    tulsi_workspace = self.workspace_root + '/tulsi-workspace'
    if os.path.islink(tulsi_workspace):
      os.unlink(tulsi_workspace)
    os.symlink(self.bazel_build_workspace_root, tulsi_workspace)
    if not os.path.exists(tulsi_workspace):
      _PrintXcodeError(
          'Linking Tulsi Workspace to %s failed.' % tulsi_workspace)
      return -1

  @staticmethod
  def _SplitPathComponents(path):
    """Splits the given path into an array of all of its components."""
    components = path.split(os.sep)
    # Patch up the first component if path started with an os.sep
    if not components[0]:
      components[0] = os.sep
    return components

  def _RunSubprocess(self, cmd):
    """Runs the given command as a subprocess, returning (exit_code, output)."""
    self._PrintVerbose('%r' % cmd, 1)
    process = subprocess.Popen(cmd,
                               stdout=subprocess.PIPE,
                               stderr=subprocess.STDOUT)
    output, _ = process.communicate()
    return (process.returncode, output)

  def _PrintVerbose(self, msg, level=0):
    if self.verbose > level:
      sys.stdout.write(msg + '\n')
      sys.stdout.flush()

  # TODO(b/35624202): Remove when target.source_map problem is resolved.
  def _PrintPathNotFoundWarning(self, path):
    _PrintXcodeWarning('Found target source path not on local filesystem: %s' %
                       path)
    _PrintXcodeWarning('Ignoring path. Debugging might not work as expected.')


if __name__ == '__main__':
  _timer = Timer('Everything', 'complete_build').Start()
  _exit_code = BazelBuildBridge().Run(sys.argv)
  _timer.End()
  sys.exit(_exit_code)