text: # Copyright 2017 The TensorFlow 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.
  # ==============================================================================
  """configure script to get build parameters from user."""
  
  from __future__ import absolute_import
  from __future__ import division
  from __future__ import print_function
  
  import argparse
  import errno
  import os
  import platform
  import re
  import subprocess
  import sys
  
  # pylint: disable=g-import-not-at-top
  try:
    from shutil import which
  except ImportError:
    from distutils.spawn import find_executable as which
  # pylint: enable=g-import-not-at-top
  
  _DEFAULT_CUDA_VERSION = '9.0'
  _DEFAULT_CUDNN_VERSION = '7'
  _DEFAULT_CUDA_COMPUTE_CAPABILITIES = '3.5,7.0'
  _DEFAULT_CUDA_PATH = '/usr/local/cuda'
  _DEFAULT_CUDA_PATH_LINUX = '/opt/cuda'
  _DEFAULT_CUDA_PATH_WIN = ('C:/Program Files/NVIDIA GPU Computing '
                            'Toolkit/CUDA/v%s' % _DEFAULT_CUDA_VERSION)
  _TF_OPENCL_VERSION = '1.2'
  _DEFAULT_COMPUTECPP_TOOLKIT_PATH = '/usr/local/computecpp'
  _DEFAULT_TRISYCL_INCLUDE_DIR = '/usr/local/triSYCL/include'
  _SUPPORTED_ANDROID_NDK_VERSIONS = [10, 11, 12, 13, 14, 15, 16]
  
  _DEFAULT_PROMPT_ASK_ATTEMPTS = 10
  
  _TF_BAZELRC_FILENAME = '.tf_configure.bazelrc'
  _TF_WORKSPACE_ROOT = ''
  _TF_BAZELRC = ''
  
  NCCL_LIB_PATHS = [
      'lib64/', 'lib/powerpc64le-linux-gnu/', 'lib/x86_64-linux-gnu/', ''
  ]
  
  if platform.machine() == 'ppc64le':
    _DEFAULT_TENSORRT_PATH_LINUX = '/usr/lib/powerpc64le-linux-gnu/'
  else:
    _DEFAULT_TENSORRT_PATH_LINUX = '/usr/lib/%s-linux-gnu' % platform.machine()
  
  
  class UserInputError(Exception):
    pass
  
  
  def is_windows():
    return platform.system() == 'Windows'
  
  
  def is_linux():
    return platform.system() == 'Linux'
  
  
  def is_macos():
    return platform.system() == 'Darwin'
  
  
  def is_ppc64le():
    return platform.machine() == 'ppc64le'
  
  
  def is_cygwin():
    return platform.system().startswith('CYGWIN_NT')
  
  
  def get_input(question):
    try:
      try:
        answer = raw_input(question)
      except NameError:
        answer = input(question)  # pylint: disable=bad-builtin
    except EOFError:
      answer = ''
    return answer
  
  
  def symlink_force(target, link_name):
    """Force symlink, equivalent of 'ln -sf'.
  
    Args:
      target: items to link to.
      link_name: name of the link.
    """
    try:
      os.symlink(target, link_name)
    except OSError as e:
      if e.errno == errno.EEXIST:
        os.remove(link_name)
        os.symlink(target, link_name)
      else:
        raise e
  
  
  def sed_in_place(filename, old, new):
    """Replace old string with new string in file.
  
    Args:
      filename: string for filename.
      old: string to replace.
      new: new string to replace to.
    """
    with open(filename, 'r') as f:
      filedata = f.read()
    newdata = filedata.replace(old, new)
    with open(filename, 'w') as f:
      f.write(newdata)
  
  
  def write_to_bazelrc(line):
    with open(_TF_BAZELRC, 'a') as f:
      f.write(line + '\n')
  
  
  def write_action_env_to_bazelrc(var_name, var):
    write_to_bazelrc('build --action_env %s="%s"' % (var_name, str(var)))
  
  
  def run_shell(cmd, allow_non_zero=False):
    if allow_non_zero:
      try:
        output = subprocess.check_output(cmd)
      except subprocess.CalledProcessError as e:
        output = e.output
    else:
      output = subprocess.check_output(cmd)
    return output.decode('UTF-8').strip()
  
  
  def cygpath(path):
    """Convert path from posix to windows."""
    return os.path.abspath(path).replace('\\', '/')
  
  
  def get_python_path(environ_cp, python_bin_path):
    """Get the python site package paths."""
    python_paths = []
    if environ_cp.get('PYTHONPATH'):
      python_paths = environ_cp.get('PYTHONPATH').split(':')
    try:
      library_paths = run_shell([
          python_bin_path, '-c',
          'import site; print("\\n".join(site.getsitepackages()))'
      ]).split('\n')
    except subprocess.CalledProcessError:
      library_paths = [
          run_shell([
              python_bin_path, '-c',
              'from distutils.sysconfig import get_python_lib;'
              'print(get_python_lib())'
          ])
      ]
  
    all_paths = set(python_paths + library_paths)
  
    paths = []
    for path in all_paths:
      if os.path.isdir(path):
        paths.append(path)
    return paths
  
  
  def get_python_major_version(python_bin_path):
    """Get the python major version."""
    return run_shell([python_bin_path, '-c', 'import sys; print(sys.version[0])'])
  
  
  def setup_python(environ_cp):
    """Setup python related env variables."""
    # Get PYTHON_BIN_PATH, default is the current running python.
    default_python_bin_path = sys.executable
    ask_python_bin_path = ('Please specify the location of python. [Default is '
                           '%s]: ') % default_python_bin_path
    while True:
      python_bin_path = get_from_env_or_user_or_default(
          environ_cp, 'PYTHON_BIN_PATH', ask_python_bin_path,
          default_python_bin_path)
      # Check if the path is valid
      if os.path.isfile(python_bin_path) and os.access(python_bin_path, os.X_OK):
        break
      elif not os.path.exists(python_bin_path):
        print('Invalid python path: %s cannot be found.' % python_bin_path)
      else:
        print('%s is not executable.  Is it the python binary?' % python_bin_path)
      environ_cp['PYTHON_BIN_PATH'] = ''
  
    # Convert python path to Windows style before checking lib and version
    if is_windows() or is_cygwin():
      python_bin_path = cygpath(python_bin_path)
  
    # Get PYTHON_LIB_PATH
    python_lib_path = environ_cp.get('PYTHON_LIB_PATH')
    if not python_lib_path:
      python_lib_paths = get_python_path(environ_cp, python_bin_path)
      if environ_cp.get('USE_DEFAULT_PYTHON_LIB_PATH') == '1':
        python_lib_path = python_lib_paths[0]
      else:
        print('Found possible Python library paths:\n  %s' %
              '\n  '.join(python_lib_paths))
        default_python_lib_path = python_lib_paths[0]
        python_lib_path = get_input(
            'Please input the desired Python library path to use.  '
            'Default is [%s]\n' % python_lib_paths[0])
        if not python_lib_path:
          python_lib_path = default_python_lib_path
      environ_cp['PYTHON_LIB_PATH'] = python_lib_path
  
    _ = get_python_major_version(python_bin_path)
  
    # Convert python path to Windows style before writing into bazel.rc
    if is_windows() or is_cygwin():
      python_lib_path = cygpath(python_lib_path)
  
    # Set-up env variables used by python_configure.bzl
    write_action_env_to_bazelrc('PYTHON_BIN_PATH', python_bin_path)
    write_action_env_to_bazelrc('PYTHON_LIB_PATH', python_lib_path)
    write_to_bazelrc('build --python_path=\"%s"' % python_bin_path)
    environ_cp['PYTHON_BIN_PATH'] = python_bin_path
  
    # Write tools/python_bin_path.sh
    with open(
        os.path.join(_TF_WORKSPACE_ROOT, 'tools', 'python_bin_path.sh'),
        'w') as f:
      f.write('export PYTHON_BIN_PATH="%s"' % python_bin_path)
  
  
  def reset_tf_configure_bazelrc():
    """Reset file that contains customized config settings."""
    open(_TF_BAZELRC, 'w').close()
    bazelrc_path = os.path.join(_TF_WORKSPACE_ROOT, '.bazelrc')
  
    data = []
    if os.path.exists(bazelrc_path):
      with open(bazelrc_path, 'r') as f:
        data = f.read().splitlines()
    with open(bazelrc_path, 'w') as f:
      for l in data:
        if _TF_BAZELRC_FILENAME in l:
          continue
        f.write('%s\n' % l)
      f.write('import %%workspace%%/%s\n' % _TF_BAZELRC_FILENAME)
  
  def cleanup_makefile():
    """Delete any leftover BUILD files from the Makefile build.
  
    These files could interfere with Bazel parsing.
    """
    makefile_download_dir = os.path.join(_TF_WORKSPACE_ROOT, 'tensorflow',
                                         'contrib', 'makefile', 'downloads')
    if os.path.isdir(makefile_download_dir):
      for root, _, filenames in os.walk(makefile_download_dir):
        for f in filenames:
          if f.endswith('BUILD'):
            os.remove(os.path.join(root, f))
  
  
  def get_var(environ_cp,
              var_name,
              query_item,
              enabled_by_default,
              question=None,
              yes_reply=None,
              no_reply=None):
    """Get boolean input from user.
  
    If var_name is not set in env, ask user to enable query_item or not. If the
    response is empty, use the default.
  
    Args:
      environ_cp: copy of the os.environ.
      var_name: string for name of environment variable, e.g. "TF_NEED_HDFS".
      query_item: string for feature related to the variable, e.g. "Hadoop File
        System".
      enabled_by_default: boolean for default behavior.
      question: optional string for how to ask for user input.
      yes_reply: optional string for reply when feature is enabled.
      no_reply: optional string for reply when feature is disabled.
  
    Returns:
      boolean value of the variable.
  
    Raises:
      UserInputError: if an environment variable is set, but it cannot be
        interpreted as a boolean indicator, assume that the user has made a
        scripting error, and will continue to provide invalid input.
        Raise the error to avoid infinitely looping.
    """
    if not question:
      question = 'Do you wish to build TensorFlow with %s support?' % query_item
    if not yes_reply:
      yes_reply = '%s support will be enabled for TensorFlow.' % query_item
    if not no_reply:
      no_reply = 'No %s' % yes_reply
  
    yes_reply += '\n'
    no_reply += '\n'
  
    if enabled_by_default:
      question += ' [Y/n]: '
    else:
      question += ' [y/N]: '
  
    var = environ_cp.get(var_name)
    if var is not None:
      var_content = var.strip().lower()
      true_strings = ('1', 't', 'true', 'y', 'yes')
      false_strings = ('0', 'f', 'false', 'n', 'no')
      if var_content in true_strings:
        var = True
      elif var_content in false_strings:
        var = False
      else:
        raise UserInputError(
            'Environment variable %s must be set as a boolean indicator.\n'
            'The following are accepted as TRUE : %s.\n'
            'The following are accepted as FALSE: %s.\n'
            'Current value is %s.' % (var_name, ', '.join(true_strings),
                                      ', '.join(false_strings), var))
  
    while var is None:
      user_input_origin = get_input(question)
      user_input = user_input_origin.strip().lower()
      if user_input == 'y':
        print(yes_reply)
        var = True
      elif user_input == 'n':
        print(no_reply)
        var = False
      elif not user_input:
        if enabled_by_default:
          print(yes_reply)
          var = True
        else:
          print(no_reply)
          var = False
      else:
        print('Invalid selection: %s' % user_input_origin)
    return var
  
  
  def set_build_var(environ_cp,
                    var_name,
                    query_item,
                    option_name,
                    enabled_by_default,
                    bazel_config_name=None):
    """Set if query_item will be enabled for the build.
  
    Ask user if query_item will be enabled. Default is used if no input is given.
    Set subprocess environment variable and write to .bazelrc if enabled.
  
    Args:
      environ_cp: copy of the os.environ.
      var_name: string for name of environment variable, e.g. "TF_NEED_HDFS".
      query_item: string for feature related to the variable, e.g. "Hadoop File
        System".
      option_name: string for option to define in .bazelrc.
      enabled_by_default: boolean for default behavior.
      bazel_config_name: Name for Bazel --config argument to enable build feature.
    """
  
    var = str(int(get_var(environ_cp, var_name, query_item, enabled_by_default)))
    environ_cp[var_name] = var
    if var == '1':
      write_to_bazelrc(
          'build:%s --define %s=true' % (bazel_config_name, option_name))
      write_to_bazelrc('build --config=%s' % bazel_config_name)
    elif bazel_config_name is not None:
      # TODO(mikecase): Migrate all users of configure.py to use --config Bazel
      # options and not to set build configs through environment variables.
      write_to_bazelrc(
          'build:%s --define %s=true' % (bazel_config_name, option_name))
  
  
  def set_action_env_var(environ_cp,
                         var_name,
                         query_item,
                         enabled_by_default,
                         question=None,
                         yes_reply=None,
                         no_reply=None):
    """Set boolean action_env variable.
  
    Ask user if query_item will be enabled. Default is used if no input is given.
    Set environment variable and write to .bazelrc.
  
    Args:
      environ_cp: copy of the os.environ.
      var_name: string for name of environment variable, e.g. "TF_NEED_HDFS".
      query_item: string for feature related to the variable, e.g. "Hadoop File
        System".
      enabled_by_default: boolean for default behavior.
      question: optional string for how to ask for user input.
      yes_reply: optional string for reply when feature is enabled.
      no_reply: optional string for reply when feature is disabled.
    """
    var = int(
        get_var(environ_cp, var_name, query_item, enabled_by_default, question,
                yes_reply, no_reply))
  
    write_action_env_to_bazelrc(var_name, var)
    environ_cp[var_name] = str(var)
  
  
  def convert_version_to_int(version):
    """Convert a version number to a integer that can be used to compare.
  
    Version strings of the form X.YZ and X.Y.Z-xxxxx are supported. The
    'xxxxx' part, for instance 'homebrew' on OS/X, is ignored.
  
    Args:
      version: a version to be converted
  
    Returns:
      An integer if converted successfully, otherwise return None.
    """
    version = version.split('-')[0]
    version_segments = version.split('.')
    for seg in version_segments:
      if not seg.isdigit():
        return None
  
    version_str = ''.join(['%03d' % int(seg) for seg in version_segments])
    return int(version_str)
  
  
  def check_bazel_version(min_version):
    """Check installed bazel version is at least min_version.
  
    Args:
      min_version: string for minimum bazel version.
  
    Returns:
      The bazel version detected.
    """
    if which('bazel') is None:
      print('Cannot find bazel. Please install bazel.')
      sys.exit(0)
    curr_version = run_shell(
        ['bazel', '--batch', '--bazelrc=/dev/null', 'version'])
  
    for line in curr_version.split('\n'):
      if 'Build label: ' in line:
        curr_version = line.split('Build label: ')[1]
        break
  
    min_version_int = convert_version_to_int(min_version)
    curr_version_int = convert_version_to_int(curr_version)
  
    # Check if current bazel version can be detected properly.
    if not curr_version_int:
      print('WARNING: current bazel installation is not a release version.')
      print('Make sure you are running at least bazel %s' % min_version)
      return curr_version
  
    print('You have bazel %s installed.' % curr_version)
  
    if curr_version_int < min_version_int:
      print('Please upgrade your bazel installation to version %s or higher to '
            'build TensorFlow!' % min_version)
      sys.exit(0)
    return curr_version
  
  
  def set_cc_opt_flags(environ_cp):
    """Set up architecture-dependent optimization flags.
  
    Also append CC optimization flags to bazel.rc..
  
    Args:
      environ_cp: copy of the os.environ.
    """
    if is_ppc64le():
      # gcc on ppc64le does not support -march, use mcpu instead
      default_cc_opt_flags = '-mcpu=native'
    elif is_windows():
      default_cc_opt_flags = '/arch:AVX'
    else:
      default_cc_opt_flags = '-march=native -Wno-sign-compare'
    question = ('Please specify optimization flags to use during compilation when'
                ' bazel option "--config=opt" is specified [Default is %s]: '
               ) % default_cc_opt_flags
    cc_opt_flags = get_from_env_or_user_or_default(environ_cp, 'CC_OPT_FLAGS',
                                                   question, default_cc_opt_flags)
    for opt in cc_opt_flags.split():
      write_to_bazelrc('build:opt --copt=%s' % opt)
    # It should be safe on the same build host.
    if not is_ppc64le() and not is_windows():
      write_to_bazelrc('build:opt --host_copt=-march=native')
    write_to_bazelrc('build:opt --define with_default_optimizations=true')
  
  
  def set_tf_cuda_clang(environ_cp):
    """set TF_CUDA_CLANG action_env.
  
    Args:
      environ_cp: copy of the os.environ.
    """
    question = 'Do you want to use clang as CUDA compiler?'
    yes_reply = 'Clang will be used as CUDA compiler.'
    no_reply = 'nvcc will be used as CUDA compiler.'
    set_action_env_var(
        environ_cp,
        'TF_CUDA_CLANG',
        None,
        False,
        question=question,
        yes_reply=yes_reply,
        no_reply=no_reply)
  
  
  def set_tf_download_clang(environ_cp):
    """Set TF_DOWNLOAD_CLANG action_env."""
    question = 'Do you wish to download a fresh release of clang? (Experimental)'
    yes_reply = 'Clang will be downloaded and used to compile tensorflow.'
    no_reply = 'Clang will not be downloaded.'
    set_action_env_var(
        environ_cp,
        'TF_DOWNLOAD_CLANG',
        None,
        False,
        question=question,
        yes_reply=yes_reply,
        no_reply=no_reply)
  
  
  def get_from_env_or_user_or_default(environ_cp, var_name, ask_for_var,
                                      var_default):
    """Get var_name either from env, or user or default.
  
    If var_name has been set as environment variable, use the preset value, else
    ask for user input. If no input is provided, the default is used.
  
    Args:
      environ_cp: copy of the os.environ.
      var_name: string for name of environment variable, e.g. "TF_NEED_HDFS".
      ask_for_var: string for how to ask for user input.
      var_default: default value string.
  
    Returns:
      string value for var_name
    """
    var = environ_cp.get(var_name)
    if not var:
      var = get_input(ask_for_var)
      print('\n')
    if not var:
      var = var_default
    return var
  
  
  def set_clang_cuda_compiler_path(environ_cp):
    """Set CLANG_CUDA_COMPILER_PATH."""
    default_clang_path = which('clang') or ''
    ask_clang_path = ('Please specify which clang should be used as device and '
                      'host compiler. [Default is %s]: ') % default_clang_path
  
    while True:
      clang_cuda_compiler_path = get_from_env_or_user_or_default(
          environ_cp, 'CLANG_CUDA_COMPILER_PATH', ask_clang_path,
          default_clang_path)
      if os.path.exists(clang_cuda_compiler_path):
        break
  
      # Reset and retry
      print('Invalid clang path: %s cannot be found.' % clang_cuda_compiler_path)
      environ_cp['CLANG_CUDA_COMPILER_PATH'] = ''
  
    # Set CLANG_CUDA_COMPILER_PATH
    environ_cp['CLANG_CUDA_COMPILER_PATH'] = clang_cuda_compiler_path
    write_action_env_to_bazelrc('CLANG_CUDA_COMPILER_PATH',
                                clang_cuda_compiler_path)
  
  
  def prompt_loop_or_load_from_env(environ_cp,
                                   var_name,
                                   var_default,
                                   ask_for_var,
                                   check_success,
                                   error_msg,
                                   suppress_default_error=False,
                                   n_ask_attempts=_DEFAULT_PROMPT_ASK_ATTEMPTS):
    """Loop over user prompts for an ENV param until receiving a valid response.
  
    For the env param var_name, read from the environment or verify user input
    until receiving valid input. When done, set var_name in the environ_cp to its
    new value.
  
    Args:
      environ_cp: (Dict) copy of the os.environ.
      var_name: (String) string for name of environment variable, e.g. "TF_MYVAR".
      var_default: (String) default value string.
      ask_for_var: (String) string for how to ask for user input.
      check_success: (Function) function that takes one argument and returns a
        boolean. Should return True if the value provided is considered valid. May
        contain a complex error message if error_msg does not provide enough
        information. In that case, set suppress_default_error to True.
      error_msg: (String) String with one and only one '%s'. Formatted with each
        invalid response upon check_success(input) failure.
      suppress_default_error: (Bool) Suppress the above error message in favor of
        one from the check_success function.
      n_ask_attempts: (Integer) Number of times to query for valid input before
        raising an error and quitting.
  
    Returns:
      [String] The value of var_name after querying for input.
  
    Raises:
      UserInputError: if a query has been attempted n_ask_attempts times without
        success, assume that the user has made a scripting error, and will
        continue to provide invalid input. Raise the error to avoid infinitely
        looping.
    """
    default = environ_cp.get(var_name) or var_default
    full_query = '%s [Default is %s]: ' % (
        ask_for_var,
        default,
    )
  
    for _ in range(n_ask_attempts):
      val = get_from_env_or_user_or_default(environ_cp, var_name, full_query,
                                            default)
      if check_success(val):
        break
      if not suppress_default_error:
        print(error_msg % val)
      environ_cp[var_name] = ''
    else:
      raise UserInputError(
          'Invalid %s setting was provided %d times in a row. '
          'Assuming to be a scripting mistake.' % (var_name, n_ask_attempts))
  
    environ_cp[var_name] = val
    return val
  
  
  def create_android_ndk_rule(environ_cp):
    """Set ANDROID_NDK_HOME and write Android NDK WORKSPACE rule."""
    if is_windows() or is_cygwin():
      default_ndk_path = cygpath(
          '%s/Android/Sdk/ndk-bundle' % environ_cp['APPDATA'])
    elif is_macos():
      default_ndk_path = '%s/library/Android/Sdk/ndk-bundle' % environ_cp['HOME']
    else:
      default_ndk_path = '%s/Android/Sdk/ndk-bundle' % environ_cp['HOME']
  
    def valid_ndk_path(path):
      return (os.path.exists(path) and
              os.path.exists(os.path.join(path, 'source.properties')))
  
    android_ndk_home_path = prompt_loop_or_load_from_env(
        environ_cp,
        var_name='ANDROID_NDK_HOME',
        var_default=default_ndk_path,
        ask_for_var='Please specify the home path of the Android NDK to use.',
        check_success=valid_ndk_path,
        error_msg=('The path %s or its child file "source.properties" '
                   'does not exist.'))
    write_action_env_to_bazelrc('ANDROID_NDK_HOME', android_ndk_home_path)
    write_action_env_to_bazelrc('ANDROID_NDK_API_LEVEL',
                                check_ndk_level(android_ndk_home_path))
  
  
  def create_android_sdk_rule(environ_cp):
    """Set Android variables and write Android SDK WORKSPACE rule."""
    if is_windows() or is_cygwin():
      default_sdk_path = cygpath('%s/Android/Sdk' % environ_cp['APPDATA'])
    elif is_macos():
      default_sdk_path = '%s/library/Android/Sdk' % environ_cp['HOME']
    else:
      default_sdk_path = '%s/Android/Sdk' % environ_cp['HOME']
  
    def valid_sdk_path(path):
      return (os.path.exists(path) and
              os.path.exists(os.path.join(path, 'platforms')) and
              os.path.exists(os.path.join(path, 'build-tools')))
  
    android_sdk_home_path = prompt_loop_or_load_from_env(
        environ_cp,
        var_name='ANDROID_SDK_HOME',
        var_default=default_sdk_path,
        ask_for_var='Please specify the home path of the Android SDK to use.',
        check_success=valid_sdk_path,
        error_msg=('Either %s does not exist, or it does not contain the '
                   'subdirectories "platforms" and "build-tools".'))
  
    platforms = os.path.join(android_sdk_home_path, 'platforms')
    api_levels = sorted(os.listdir(platforms))
    api_levels = [x.replace('android-', '') for x in api_levels]
  
    def valid_api_level(api_level):
      return os.path.exists(
          os.path.join(android_sdk_home_path, 'platforms',
                       'android-' + api_level))
  
    android_api_level = prompt_loop_or_load_from_env(
        environ_cp,
        var_name='ANDROID_API_LEVEL',
        var_default=api_levels[-1],
        ask_for_var=('Please specify the Android SDK API level to use. '
                     '[Available levels: %s]') % api_levels,
        check_success=valid_api_level,
        error_msg='Android-%s is not present in the SDK path.')
  
    build_tools = os.path.join(android_sdk_home_path, 'build-tools')
    versions = sorted(os.listdir(build_tools))
  
    def valid_build_tools(version):
      return os.path.exists(
          os.path.join(android_sdk_home_path, 'build-tools', version))
  
    android_build_tools_version = prompt_loop_or_load_from_env(
        environ_cp,
        var_name='ANDROID_BUILD_TOOLS_VERSION',
        var_default=versions[-1],
        ask_for_var=('Please specify an Android build tools version to use. '
                     '[Available versions: %s]') % versions,
        check_success=valid_build_tools,
        error_msg=('The selected SDK does not have build-tools version %s '
                   'available.'))
  
    write_action_env_to_bazelrc('ANDROID_BUILD_TOOLS_VERSION',
                                android_build_tools_version)
    write_action_env_to_bazelrc('ANDROID_SDK_API_LEVEL', android_api_level)
    write_action_env_to_bazelrc('ANDROID_SDK_HOME', android_sdk_home_path)
  
  
  def check_ndk_level(android_ndk_home_path):
    """Check the revision number of an Android NDK path."""
    properties_path = '%s/source.properties' % android_ndk_home_path
    if is_windows() or is_cygwin():
      properties_path = cygpath(properties_path)
    with open(properties_path, 'r') as f:
      filedata = f.read()
  
    revision = re.search(r'Pkg.Revision = (\d+)', filedata)
    if revision:
      ndk_api_level = revision.group(1)
    else:
      raise Exception('Unable to parse NDK revision.')
    if int(ndk_api_level) not in _SUPPORTED_ANDROID_NDK_VERSIONS:
      print('WARNING: The API level of the NDK in %s is %s, which is not '
            'supported by Bazel (officially supported versions: %s). Please use '
            'another version. Compiling Android targets may result in confusing '
            'errors.\n' % (android_ndk_home_path, ndk_api_level,
                           _SUPPORTED_ANDROID_NDK_VERSIONS))
    return ndk_api_level
  
  
  def set_gcc_host_compiler_path(environ_cp):
    """Set GCC_HOST_COMPILER_PATH."""
    default_gcc_host_compiler_path = which('gcc') or ''
    cuda_bin_symlink = '%s/bin/gcc' % environ_cp.get('CUDA_TOOLKIT_PATH')
  
    if os.path.islink(cuda_bin_symlink):
      # os.readlink is only available in linux
      default_gcc_host_compiler_path = os.path.realpath(cuda_bin_symlink)
  
    gcc_host_compiler_path = prompt_loop_or_load_from_env(
        environ_cp,
        var_name='GCC_HOST_COMPILER_PATH',
        var_default=default_gcc_host_compiler_path,
        ask_for_var=
        'Please specify which gcc should be used by nvcc as the host compiler.',
        check_success=os.path.exists,
        error_msg='Invalid gcc path. %s cannot be found.',
    )
  
    write_action_env_to_bazelrc('GCC_HOST_COMPILER_PATH', gcc_host_compiler_path)
  
  
  def reformat_version_sequence(version_str, sequence_count):
    """Reformat the version string to have the given number of sequences.
  
    For example:
    Given (7, 2) -> 7.0
          (7.0.1, 2) -> 7.0
          (5, 1) -> 5
          (5.0.3.2, 1) -> 5
  
    Args:
        version_str: String, the version string.
        sequence_count: int, an integer.
  
    Returns:
        string, reformatted version string.
    """
    v = version_str.split('.')
    if len(v) < sequence_count:
      v = v + (['0'] * (sequence_count - len(v)))
  
    return '.'.join(v[:sequence_count])
  
  
  def set_tf_cuda_version(environ_cp):
    """Set CUDA_TOOLKIT_PATH and TF_CUDA_VERSION."""
    ask_cuda_version = (
        'Please specify the CUDA SDK version you want to use. '
        '[Leave empty to default to CUDA %s]: ') % _DEFAULT_CUDA_VERSION
  
    for _ in range(_DEFAULT_PROMPT_ASK_ATTEMPTS):
      # Configure the Cuda SDK version to use.
      tf_cuda_version = get_from_env_or_user_or_default(
          environ_cp, 'TF_CUDA_VERSION', ask_cuda_version, _DEFAULT_CUDA_VERSION)
      tf_cuda_version = reformat_version_sequence(str(tf_cuda_version), 2)
  
      # Find out where the CUDA toolkit is installed
      default_cuda_path = _DEFAULT_CUDA_PATH
      if is_windows() or is_cygwin():
        default_cuda_path = cygpath(
            environ_cp.get('CUDA_PATH', _DEFAULT_CUDA_PATH_WIN))
      elif is_linux():
        # If the default doesn't exist, try an alternative default.
        if (not os.path.exists(default_cuda_path)
           ) and os.path.exists(_DEFAULT_CUDA_PATH_LINUX):
          default_cuda_path = _DEFAULT_CUDA_PATH_LINUX
      ask_cuda_path = ('Please specify the location where CUDA %s toolkit is'
                       ' installed. Refer to README.md for more details. '
                       '[Default is %s]: ') % (tf_cuda_version, default_cuda_path)
      cuda_toolkit_path = get_from_env_or_user_or_default(
          environ_cp, 'CUDA_TOOLKIT_PATH', ask_cuda_path, default_cuda_path)
      if is_windows() or is_cygwin():
        cuda_toolkit_path = cygpath(cuda_toolkit_path)
  
      if is_windows():
        cuda_rt_lib_paths = ['lib/x64/cudart.lib']
      elif is_linux():
        cuda_rt_lib_paths = [
            '%s/libcudart.so.%s' % (x, tf_cuda_version) for x in [
                'lib64',
                'lib/powerpc64le-linux-gnu',
                'lib/x86_64-linux-gnu',
            ]
        ]
      elif is_macos():
        cuda_rt_lib_paths = ['lib/libcudart.%s.dylib' % tf_cuda_version]
  
      cuda_toolkit_paths_full = [
          os.path.join(cuda_toolkit_path, x) for x in cuda_rt_lib_paths
      ]
      if any([os.path.exists(x) for x in cuda_toolkit_paths_full]):
        break
  
      # Reset and retry
      print('Invalid path to CUDA %s toolkit. %s cannot be found' %
            (tf_cuda_version, cuda_toolkit_paths_full))
      environ_cp['TF_CUDA_VERSION'] = ''
      environ_cp['CUDA_TOOLKIT_PATH'] = ''
  
    else:
      raise UserInputError('Invalid TF_CUDA_SETTING setting was provided %d '
                           'times in a row. Assuming to be a scripting mistake.' %
                           _DEFAULT_PROMPT_ASK_ATTEMPTS)
  
    # Set CUDA_TOOLKIT_PATH and TF_CUDA_VERSION
    environ_cp['CUDA_TOOLKIT_PATH'] = cuda_toolkit_path
    write_action_env_to_bazelrc('CUDA_TOOLKIT_PATH', cuda_toolkit_path)
    environ_cp['TF_CUDA_VERSION'] = tf_cuda_version
    write_action_env_to_bazelrc('TF_CUDA_VERSION', tf_cuda_version)
  
  
  def set_tf_cudnn_version(environ_cp):
    """Set CUDNN_INSTALL_PATH and TF_CUDNN_VERSION."""
    ask_cudnn_version = (
        'Please specify the cuDNN version you want to use. '
        '[Leave empty to default to cuDNN %s]: ') % _DEFAULT_CUDNN_VERSION
  
    for _ in range(_DEFAULT_PROMPT_ASK_ATTEMPTS):
      tf_cudnn_version = get_from_env_or_user_or_default(
          environ_cp, 'TF_CUDNN_VERSION', ask_cudnn_version,
          _DEFAULT_CUDNN_VERSION)
      tf_cudnn_version = reformat_version_sequence(str(tf_cudnn_version), 1)
  
      default_cudnn_path = environ_cp.get('CUDA_TOOLKIT_PATH')
      ask_cudnn_path = (r'Please specify the location where cuDNN %s library is '
                        'installed. Refer to README.md for more details. [Default'
                        ' is %s]: ') % (tf_cudnn_version, default_cudnn_path)
      cudnn_install_path = get_from_env_or_user_or_default(
          environ_cp, 'CUDNN_INSTALL_PATH', ask_cudnn_path, default_cudnn_path)
  
      # Result returned from "read" will be used unexpanded. That make "~"
      # unusable. Going through one more level of expansion to handle that.
      cudnn_install_path = os.path.realpath(
          os.path.expanduser(cudnn_install_path))
      if is_windows() or is_cygwin():
        cudnn_install_path = cygpath(cudnn_install_path)
  
      if is_windows():
        cuda_dnn_lib_path = 'lib/x64/cudnn.lib'
        cuda_dnn_lib_alt_path = 'lib/x64/cudnn.lib'
      elif is_linux():
        cuda_dnn_lib_path = 'lib64/libcudnn.so.%s' % tf_cudnn_version
        cuda_dnn_lib_alt_path = 'libcudnn.so.%s' % tf_cudnn_version
      elif is_macos():
        cuda_dnn_lib_path = 'lib/libcudnn.%s.dylib' % tf_cudnn_version
        cuda_dnn_lib_alt_path = 'libcudnn.%s.dylib' % tf_cudnn_version
  
      cuda_dnn_lib_path_full = os.path.join(cudnn_install_path, cuda_dnn_lib_path)
      cuda_dnn_lib_alt_path_full = os.path.join(cudnn_install_path,
                                                cuda_dnn_lib_alt_path)
      if os.path.exists(cuda_dnn_lib_path_full) or os.path.exists(
          cuda_dnn_lib_alt_path_full):
        break
  
      # Try another alternative for Linux
      if is_linux():
        ldconfig_bin = which('ldconfig') or '/sbin/ldconfig'
        cudnn_path_from_ldconfig = run_shell([ldconfig_bin, '-p'])
        cudnn_path_from_ldconfig = re.search('.*libcudnn.so .* => (.*)',
                                             cudnn_path_from_ldconfig)
        if cudnn_path_from_ldconfig:
          cudnn_path_from_ldconfig = cudnn_path_from_ldconfig.group(1)
          if os.path.exists(
              '%s.%s' % (cudnn_path_from_ldconfig, tf_cudnn_version)):
            cudnn_install_path = os.path.dirname(cudnn_path_from_ldconfig)
            break
  
      # Reset and Retry
      print(
          'Invalid path to cuDNN %s toolkit. None of the following files can be '
          'found:' % tf_cudnn_version)
      print(cuda_dnn_lib_path_full)
      print(cuda_dnn_lib_alt_path_full)
      if is_linux():
        print('%s.%s' % (cudnn_path_from_ldconfig, tf_cudnn_version))
  
      environ_cp['TF_CUDNN_VERSION'] = ''
    else:
      raise UserInputError('Invalid TF_CUDNN setting was provided %d '
                           'times in a row. Assuming to be a scripting mistake.' %
                           _DEFAULT_PROMPT_ASK_ATTEMPTS)
  
    # Set CUDNN_INSTALL_PATH and TF_CUDNN_VERSION
    environ_cp['CUDNN_INSTALL_PATH'] = cudnn_install_path
    write_action_env_to_bazelrc('CUDNN_INSTALL_PATH', cudnn_install_path)
    environ_cp['TF_CUDNN_VERSION'] = tf_cudnn_version
    write_action_env_to_bazelrc('TF_CUDNN_VERSION', tf_cudnn_version)
  
  
  def is_cuda_compatible(lib, cuda_ver, cudnn_ver):
    """Check compatibility between given library and cudnn/cudart libraries."""
    ldd_bin = which('ldd') or '/usr/bin/ldd'
    ldd_out = run_shell([ldd_bin, lib], True)
    ldd_out = ldd_out.split(os.linesep)
    cudnn_pattern = re.compile('.*libcudnn.so\\.?(.*) =>.*$')
    cuda_pattern = re.compile('.*libcudart.so\\.?(.*) =>.*$')
    cudnn = None
    cudart = None
    cudnn_ok = True  # assume no cudnn dependency by default
    cuda_ok = True  # assume no cuda dependency by default
    for line in ldd_out:
      if 'libcudnn.so' in line:
        cudnn = cudnn_pattern.search(line)
        cudnn_ok = False
      elif 'libcudart.so' in line:
        cudart = cuda_pattern.search(line)
        cuda_ok = False
    if cudnn and len(cudnn.group(1)):
      cudnn = convert_version_to_int(cudnn.group(1))
    if cudart and len(cudart.group(1)):
      cudart = convert_version_to_int(cudart.group(1))
    if cudnn is not None:
      cudnn_ok = (cudnn == cudnn_ver)
    if cudart is not None:
      cuda_ok = (cudart == cuda_ver)
    return cudnn_ok and cuda_ok
  
  
  def set_tf_tensorrt_install_path(environ_cp):
    """Set TENSORRT_INSTALL_PATH and TF_TENSORRT_VERSION.
  
    Adapted from code contributed by Sami Kama (https://github.com/samikama).
  
    Args:
      environ_cp: copy of the os.environ.
  
    Raises:
      ValueError: if this method was called under non-Linux platform.
      UserInputError: if user has provided invalid input multiple times.
    """
    if not is_linux():
      raise ValueError('Currently TensorRT is only supported on Linux platform.')
  
    # Ask user whether to add TensorRT support.
    if str(int(get_var(environ_cp, 'TF_NEED_TENSORRT', 'TensorRT',
                       False))) != '1':
      return
  
    for _ in range(_DEFAULT_PROMPT_ASK_ATTEMPTS):
      ask_tensorrt_path = (r'Please specify the location where TensorRT is '
                           'installed. [Default is %s]:') % (
                               _DEFAULT_TENSORRT_PATH_LINUX)
      trt_install_path = get_from_env_or_user_or_default(
          environ_cp, 'TENSORRT_INSTALL_PATH', ask_tensorrt_path,
          _DEFAULT_TENSORRT_PATH_LINUX)
  
      # Result returned from "read" will be used unexpanded. That make "~"
      # unusable. Going through one more level of expansion to handle that.
      trt_install_path = os.path.realpath(os.path.expanduser(trt_install_path))
  
      def find_libs(search_path):
        """Search for libnvinfer.so in "search_path"."""
        fl = set()
        if os.path.exists(search_path) and os.path.isdir(search_path):
          fl.update([
              os.path.realpath(os.path.join(search_path, x))
              for x in os.listdir(search_path)
              if 'libnvinfer.so' in x
          ])
        return fl
  
      possible_files = find_libs(trt_install_path)
      possible_files.update(find_libs(os.path.join(trt_install_path, 'lib')))
      possible_files.update(find_libs(os.path.join(trt_install_path, 'lib64')))
      cuda_ver = convert_version_to_int(environ_cp['TF_CUDA_VERSION'])
      cudnn_ver = convert_version_to_int(environ_cp['TF_CUDNN_VERSION'])
      nvinfer_pattern = re.compile('.*libnvinfer.so.?(.*)$')
      highest_ver = [0, None, None]
  
      for lib_file in possible_files:
        if is_cuda_compatible(lib_file, cuda_ver, cudnn_ver):
          matches = nvinfer_pattern.search(lib_file)
          if not matches.groups():
            continue
          ver_str = matches.group(1)
          ver = convert_version_to_int(ver_str) if len(ver_str) else 0
          if ver > highest_ver[0]:
            highest_ver = [ver, ver_str, lib_file]
      if highest_ver[1] is not None:
        trt_install_path = os.path.dirname(highest_ver[2])
        tf_tensorrt_version = highest_ver[1]
        break
  
      # Try another alternative from ldconfig.
      ldconfig_bin = which('ldconfig') or '/sbin/ldconfig'
      ldconfig_output = run_shell([ldconfig_bin, '-p'])
      search_result = re.search('.*libnvinfer.so\\.?([0-9.]*).* => (.*)',
                                ldconfig_output)
      if search_result:
        libnvinfer_path_from_ldconfig = search_result.group(2)
        if os.path.exists(libnvinfer_path_from_ldconfig):
          if is_cuda_compatible(libnvinfer_path_from_ldconfig, cuda_ver,
                                cudnn_ver):
            trt_install_path = os.path.dirname(libnvinfer_path_from_ldconfig)
            tf_tensorrt_version = search_result.group(1)
            break
  
      # Reset and Retry
      if possible_files:
        print('TensorRT libraries found in one the following directories',
              'are not compatible with selected cuda and cudnn installations')
        print(trt_install_path)
        print(os.path.join(trt_install_path, 'lib'))
        print(os.path.join(trt_install_path, 'lib64'))
        if search_result:
          print(libnvinfer_path_from_ldconfig)
      else:
        print(
            'Invalid path to TensorRT. None of the following files can be found:')
        print(trt_install_path)
        print(os.path.join(trt_install_path, 'lib'))
        print(os.path.join(trt_install_path, 'lib64'))
        if search_result:
          print(libnvinfer_path_from_ldconfig)
  
    else:
      raise UserInputError('Invalid TF_TENSORRT setting was provided %d '
                           'times in a row. Assuming to be a scripting mistake.' %
                           _DEFAULT_PROMPT_ASK_ATTEMPTS)
  
    # Set TENSORRT_INSTALL_PATH and TF_TENSORRT_VERSION
    environ_cp['TENSORRT_INSTALL_PATH'] = trt_install_path
    write_action_env_to_bazelrc('TENSORRT_INSTALL_PATH', trt_install_path)
    environ_cp['TF_TENSORRT_VERSION'] = tf_tensorrt_version
    write_action_env_to_bazelrc('TF_TENSORRT_VERSION', tf_tensorrt_version)
  
  
  def set_tf_nccl_install_path(environ_cp):
    """Set NCCL_INSTALL_PATH, NCCL_HDR_PATH and TF_NCCL_VERSION.
  
    Args:
      environ_cp: copy of the os.environ.
  
    Raises:
      ValueError: if this method was called under non-Linux platform.
      UserInputError: if user has provided invalid input multiple times.
    """
    if not is_linux():
      raise ValueError('Currently NCCL is only supported on Linux platforms.')
  
    ask_nccl_version = (
        'Please specify the locally installed NCCL version you want to use. '
        '[Default is to use https://github.com/nvidia/nccl]: ')
  
    for _ in range(_DEFAULT_PROMPT_ASK_ATTEMPTS):
      tf_nccl_version = get_from_env_or_user_or_default(
          environ_cp, 'TF_NCCL_VERSION', ask_nccl_version, '')
  
      if not tf_nccl_version:
        break  # No need to get install path, building the open source code.
  
      tf_nccl_version = reformat_version_sequence(str(tf_nccl_version), 1)
  
      # Look with ldconfig first if we can find the library in paths
      # like /usr/lib/x86_64-linux-gnu and the header file in the corresponding
      # include directory. This is where the NCCL .deb packages install them.
  
      # First check to see if NCCL is in the ldconfig.
      # If its found, use that location.
      if is_linux():
        ldconfig_bin = which('ldconfig') or '/sbin/ldconfig'
        nccl2_path_from_ldconfig = run_shell([ldconfig_bin, '-p'])
        nccl2_path_from_ldconfig = re.search('.*libnccl.so .* => (.*)',
                                             nccl2_path_from_ldconfig)
      if nccl2_path_from_ldconfig:
        nccl2_path_from_ldconfig = nccl2_path_from_ldconfig.group(1)
        if os.path.exists('%s.%s' % (nccl2_path_from_ldconfig, tf_nccl_version)):
          nccl_install_path = os.path.dirname(nccl2_path_from_ldconfig)
          print('NCCL libraries found in ' + nccl2_path_from_ldconfig)
  
          # Check if this is the main system lib location
          if re.search('.*linux-gnu', nccl_install_path):
            trunc_nccl_install_path = '/usr'
            print('This looks like a system path.')
          else:
            trunc_nccl_install_path = nccl_install_path + '/..'
  
          # Look for header
          nccl_hdr_path = trunc_nccl_install_path + '/include'
          print('Assuming NCCL header path is ' + nccl_hdr_path)
          if os.path.exists(nccl_hdr_path + '/nccl.h'):
            # Set NCCL_INSTALL_PATH
            environ_cp['NCCL_INSTALL_PATH'] = nccl_install_path
            write_action_env_to_bazelrc('NCCL_INSTALL_PATH', nccl_install_path)
  
            # Set NCCL_HDR_PATH
            environ_cp['NCCL_HDR_PATH'] = nccl_hdr_path
            write_action_env_to_bazelrc('NCCL_HDR_PATH', nccl_hdr_path)
            break
          else:
            print(
                'The header for NCCL2 cannot be found. Please install the libnccl-dev package.'
            )
        else:
          print('NCCL2 is listed by ldconfig but the library is not found. '
                'Your ldconfig is out of date. Please run sudo ldconfig.')
      else:
        # NCCL is not found in ldconfig. Ask the user for the location.
        default_nccl_path = environ_cp.get('CUDA_TOOLKIT_PATH')
        ask_nccl_path = (
            r'Please specify the location where NCCL %s library is '
            'installed. Refer to README.md for more details. [Default '
            'is %s]:') % (tf_nccl_version, default_nccl_path)
        nccl_install_path = get_from_env_or_user_or_default(
            environ_cp, 'NCCL_INSTALL_PATH', ask_nccl_path, default_nccl_path)
  
        # Result returned from "read" will be used unexpanded. That make "~"
        # unusable. Going through one more level of expansion to handle that.
        nccl_install_path = os.path.realpath(
            os.path.expanduser(nccl_install_path))
        if is_windows() or is_cygwin():
          nccl_install_path = cygpath(nccl_install_path)
  
        nccl_lib_path = ''
        if is_windows():
          nccl_lib_path = 'lib/x64/nccl.lib'
        elif is_linux():
          nccl_lib_filename = 'libnccl.so.%s' % tf_nccl_version
          nccl_lpath = '%s/lib/%s' % (nccl_install_path, nccl_lib_filename)
          if not os.path.exists(nccl_lpath):
            for relative_path in NCCL_LIB_PATHS:
              path = '%s/%s%s' % (nccl_install_path, relative_path,
                                  nccl_lib_filename)
              if os.path.exists(path):
                print('NCCL found at ' + path)
                nccl_lib_path = path
                break
          else:
            nccl_lib_path = nccl_lpath
        elif is_macos():
          nccl_lib_path = 'lib/libnccl.%s.dylib' % tf_nccl_version
  
        nccl_lib_path = os.path.join(nccl_install_path, nccl_lib_path)
        nccl_hdr_path = os.path.join(
            os.path.dirname(nccl_lib_path), '../include/nccl.h')
        print('Assuming NCCL header path is ' + nccl_hdr_path)
        if os.path.exists(nccl_lib_path) and os.path.exists(nccl_hdr_path):
          # Set NCCL_INSTALL_PATH
          environ_cp['NCCL_INSTALL_PATH'] = os.path.dirname(nccl_lib_path)
          write_action_env_to_bazelrc('NCCL_INSTALL_PATH',
                                      os.path.dirname(nccl_lib_path))
  
          # Set NCCL_HDR_PATH
          environ_cp['NCCL_HDR_PATH'] = os.path.dirname(nccl_hdr_path)
          write_action_env_to_bazelrc('NCCL_HDR_PATH',
                                      os.path.dirname(nccl_hdr_path))
          break
  
        # Reset and Retry
        print(
            'Invalid path to NCCL %s toolkit, %s or %s not found. Please use the '
            'O/S agnostic package of NCCL 2' % (tf_nccl_version, nccl_lib_path,
                                                nccl_hdr_path))
  
        environ_cp['TF_NCCL_VERSION'] = ''
    else:
      raise UserInputError('Invalid TF_NCCL setting was provided %d '
                           'times in a row. Assuming to be a scripting mistake.' %
                           _DEFAULT_PROMPT_ASK_ATTEMPTS)
  
    # Set TF_NCCL_VERSION
    environ_cp['TF_NCCL_VERSION'] = tf_nccl_version
    write_action_env_to_bazelrc('TF_NCCL_VERSION', tf_nccl_version)
  
  def get_native_cuda_compute_capabilities(environ_cp):
    """Get native cuda compute capabilities.
  
    Args:
      environ_cp: copy of the os.environ.
  
    Returns:
      string of native cuda compute capabilities, separated by comma.
    """
    device_query_bin = os.path.join(
        environ_cp.get('CUDA_TOOLKIT_PATH'), 'extras/demo_suite/deviceQuery')
    if os.path.isfile(device_query_bin) and os.access(device_query_bin, os.X_OK):
      try:
        output = run_shell(device_query_bin).split('\n')
        pattern = re.compile('[0-9]*\\.[0-9]*')
        output = [pattern.search(x) for x in output if 'Capability' in x]
        output = ','.join(x.group() for x in output if x is not None)
      except subprocess.CalledProcessError:
        output = ''
    else:
      output = ''
    return output
  
  
  def set_tf_cuda_compute_capabilities(environ_cp):
    """Set TF_CUDA_COMPUTE_CAPABILITIES."""
    while True:
      native_cuda_compute_capabilities = get_native_cuda_compute_capabilities(
          environ_cp)
      if not native_cuda_compute_capabilities:
        default_cuda_compute_capabilities = _DEFAULT_CUDA_COMPUTE_CAPABILITIES
      else:
        default_cuda_compute_capabilities = native_cuda_compute_capabilities
  
      ask_cuda_compute_capabilities = (
          'Please specify a list of comma-separated '
          'Cuda compute capabilities you want to '
          'build with.\nYou can find the compute '
          'capability of your device at: '
          'https://developer.nvidia.com/cuda-gpus.\nPlease'
          ' note that each additional compute '
          'capability significantly increases your '
          'build time and binary size. [Default is: %s]: ' %
          default_cuda_compute_capabilities)
      tf_cuda_compute_capabilities = get_from_env_or_user_or_default(
          environ_cp, 'TF_CUDA_COMPUTE_CAPABILITIES',
          ask_cuda_compute_capabilities, default_cuda_compute_capabilities)
      # Check whether all capabilities from the input is valid
      all_valid = True
      # Remove all whitespace characters before splitting the string
      # that users may insert by accident, as this will result in error
      tf_cuda_compute_capabilities = ''.join(tf_cuda_compute_capabilities.split())
      for compute_capability in tf_cuda_compute_capabilities.split(','):
        m = re.match('[0-9]+.[0-9]+', compute_capability)
        if not m:
          print('Invalid compute capability: ' % compute_capability)
          all_valid = False
        else:
          ver = int(m.group(0).split('.')[0])
          if ver < 3:
            print('Only compute capabilities 3.0 or higher are supported.')
            all_valid = False
  
      if all_valid:
        break
  
      # Reset and Retry
      environ_cp['TF_CUDA_COMPUTE_CAPABILITIES'] = ''
  
    # Set TF_CUDA_COMPUTE_CAPABILITIES
    environ_cp['TF_CUDA_COMPUTE_CAPABILITIES'] = tf_cuda_compute_capabilities
    write_action_env_to_bazelrc('TF_CUDA_COMPUTE_CAPABILITIES',
                                tf_cuda_compute_capabilities)
  
  
  def set_other_cuda_vars(environ_cp):
    """Set other CUDA related variables."""
    # If CUDA is enabled, always use GPU during build and test.
    if environ_cp.get('TF_CUDA_CLANG') == '1':
      write_to_bazelrc('build --config=cuda_clang')
      write_to_bazelrc('test --config=cuda_clang')
    else:
      write_to_bazelrc('build --config=cuda')
      write_to_bazelrc('test --config=cuda')
  
  
  def set_host_cxx_compiler(environ_cp):
    """Set HOST_CXX_COMPILER."""
    default_cxx_host_compiler = which('g++') or ''
  
    host_cxx_compiler = prompt_loop_or_load_from_env(
        environ_cp,
        var_name='HOST_CXX_COMPILER',
        var_default=default_cxx_host_compiler,
        ask_for_var=('Please specify which C++ compiler should be used as the '
                     'host C++ compiler.'),
        check_success=os.path.exists,
        error_msg='Invalid C++ compiler path. %s cannot be found.',
    )
  
    write_action_env_to_bazelrc('HOST_CXX_COMPILER', host_cxx_compiler)
  
  
  def set_host_c_compiler(environ_cp):
    """Set HOST_C_COMPILER."""
    default_c_host_compiler = which('gcc') or ''
  
    host_c_compiler = prompt_loop_or_load_from_env(
        environ_cp,
        var_name='HOST_C_COMPILER',
        var_default=default_c_host_compiler,
        ask_for_var=('Please specify which C compiler should be used as the host '
                     'C compiler.'),
        check_success=os.path.exists,
        error_msg='Invalid C compiler path. %s cannot be found.',
    )
  
    write_action_env_to_bazelrc('HOST_C_COMPILER', host_c_compiler)
  
  
  def set_computecpp_toolkit_path(environ_cp):
    """Set COMPUTECPP_TOOLKIT_PATH."""
  
    def toolkit_exists(toolkit_path):
      """Check if a computecpp toolkit path is valid."""
      if is_linux():
        sycl_rt_lib_path = 'lib/libComputeCpp.so'
      else:
        sycl_rt_lib_path = ''
  
      sycl_rt_lib_path_full = os.path.join(toolkit_path, sycl_rt_lib_path)
      exists = os.path.exists(sycl_rt_lib_path_full)
      if not exists:
        print('Invalid SYCL %s library path. %s cannot be found' %
              (_TF_OPENCL_VERSION, sycl_rt_lib_path_full))
      return exists
  
    computecpp_toolkit_path = prompt_loop_or_load_from_env(
        environ_cp,
        var_name='COMPUTECPP_TOOLKIT_PATH',
        var_default=_DEFAULT_COMPUTECPP_TOOLKIT_PATH,
        ask_for_var=(
            'Please specify the location where ComputeCpp for SYCL %s is '
            'installed.' % _TF_OPENCL_VERSION),
        check_success=toolkit_exists,
        error_msg='Invalid SYCL compiler path. %s cannot be found.',
        suppress_default_error=True)
  
    write_action_env_to_bazelrc('COMPUTECPP_TOOLKIT_PATH',
                                computecpp_toolkit_path)
  
  
  def set_trisycl_include_dir(environ_cp):
    """Set TRISYCL_INCLUDE_DIR."""
  
    ask_trisycl_include_dir = ('Please specify the location of the triSYCL '
                               'include directory. (Use --config=sycl_trisycl '
                               'when building with Bazel) '
                               '[Default is %s]: ') % (
                                   _DEFAULT_TRISYCL_INCLUDE_DIR)
  
    while True:
      trisycl_include_dir = get_from_env_or_user_or_default(
          environ_cp, 'TRISYCL_INCLUDE_DIR', ask_trisycl_include_dir,
          _DEFAULT_TRISYCL_INCLUDE_DIR)
      if os.path.exists(trisycl_include_dir):
        break
  
      print('Invalid triSYCL include directory, %s cannot be found' %
            (trisycl_include_dir))
  
    # Set TRISYCL_INCLUDE_DIR
    environ_cp['TRISYCL_INCLUDE_DIR'] = trisycl_include_dir
    write_action_env_to_bazelrc('TRISYCL_INCLUDE_DIR', trisycl_include_dir)
  
  
  def set_mpi_home(environ_cp):
    """Set MPI_HOME."""
  
    default_mpi_home = which('mpirun') or which('mpiexec') or ''
    default_mpi_home = os.path.dirname(os.path.dirname(default_mpi_home))
  
    def valid_mpi_path(mpi_home):
      exists = (
          os.path.exists(os.path.join(mpi_home, 'include')) and
          (os.path.exists(os.path.join(mpi_home, 'lib')) or
           os.path.exists(os.path.join(mpi_home, 'lib64')) or
           os.path.exists(os.path.join(mpi_home, 'lib32'))))
      if not exists:
        print(
            'Invalid path to the MPI Toolkit. %s or %s or %s or %s cannot be found'
            % (os.path.join(mpi_home, 'include'),
               os.path.exists(os.path.join(mpi_home, 'lib')),
               os.path.exists(os.path.join(mpi_home, 'lib64')),
               os.path.exists(os.path.join(mpi_home, 'lib32'))))
      return exists
  
    _ = prompt_loop_or_load_from_env(
        environ_cp,
        var_name='MPI_HOME',
        var_default=default_mpi_home,
        ask_for_var='Please specify the MPI toolkit folder.',
        check_success=valid_mpi_path,
        error_msg='',
        suppress_default_error=True)
  
  
  def set_other_mpi_vars(environ_cp):
    """Set other MPI related variables."""
    # Link the MPI header files
    mpi_home = environ_cp.get('MPI_HOME')
    symlink_force('%s/include/mpi.h' % mpi_home, 'third_party/mpi/mpi.h')
  
    # Determine if we use OpenMPI or MVAPICH, these require different header files
    # to be included here to make bazel dependency checker happy
    if os.path.exists(os.path.join(mpi_home, 'include/mpi_portable_platform.h')):
      symlink_force(
          os.path.join(mpi_home, 'include/mpi_portable_platform.h'),
          'third_party/mpi/mpi_portable_platform.h')
      # TODO(gunan): avoid editing files in configure
      sed_in_place('third_party/mpi/mpi.bzl', 'MPI_LIB_IS_OPENMPI=False',
                   'MPI_LIB_IS_OPENMPI=True')
    else:
      # MVAPICH / MPICH
      symlink_force(
          os.path.join(mpi_home, 'include/mpio.h'), 'third_party/mpi/mpio.h')
      symlink_force(
          os.path.join(mpi_home, 'include/mpicxx.h'), 'third_party/mpi/mpicxx.h')
      # TODO(gunan): avoid editing files in configure
      sed_in_place('third_party/mpi/mpi.bzl', 'MPI_LIB_IS_OPENMPI=True',
                   'MPI_LIB_IS_OPENMPI=False')
  
    if os.path.exists(os.path.join(mpi_home, 'lib/libmpi.so')):
      symlink_force(
          os.path.join(mpi_home, 'lib/libmpi.so'), 'third_party/mpi/libmpi.so')
    elif os.path.exists(os.path.join(mpi_home, 'lib64/libmpi.so')):
      symlink_force(
          os.path.join(mpi_home, 'lib64/libmpi.so'), 'third_party/mpi/libmpi.so')
    elif os.path.exists(os.path.join(mpi_home, 'lib32/libmpi.so')):
      symlink_force(
          os.path.join(mpi_home, 'lib32/libmpi.so'), 'third_party/mpi/libmpi.so')
  
    else:
      raise ValueError(
          'Cannot find the MPI library file in %s/lib or %s/lib64 or %s/lib32' %
          mpi_home, mpi_home, mpi_home)
  
  
  def set_system_libs_flag(environ_cp):
    syslibs = environ_cp.get('TF_SYSTEM_LIBS', '')
    if syslibs:
      if ',' in syslibs:
        syslibs = ','.join(sorted(syslibs.split(',')))
      else:
        syslibs = ','.join(sorted(syslibs.split()))
      write_action_env_to_bazelrc('TF_SYSTEM_LIBS', syslibs)
  
    if 'PREFIX' in environ_cp:
      write_to_bazelrc('build --define=PREFIX=%s' % environ_cp['PREFIX'])
    if 'LIBDIR' in environ_cp:
      write_to_bazelrc('build --define=LIBDIR=%s' % environ_cp['LIBDIR'])
    if 'INCLUDEDIR' in environ_cp:
      write_to_bazelrc('build --define=INCLUDEDIR=%s' % environ_cp['INCLUDEDIR'])
  
  
  def set_windows_build_flags(environ_cp):
    """Set Windows specific build options."""
    # The non-monolithic build is not supported yet
    write_to_bazelrc('build --config monolithic')
    # Suppress warning messages
    write_to_bazelrc('build --copt=-w --host_copt=-w')
    # Output more verbose information when something goes wrong
    write_to_bazelrc('build --verbose_failures')
    # The host and target platforms are the same in Windows build. So we don't
    # have to distinct them. This avoids building the same targets twice.
    write_to_bazelrc('build --distinct_host_configuration=false')
    # Enable short object file path to avoid long path issue on Windows.
    # TODO(pcloudy): Remove this flag when upgrading Bazel to 0.16.0
    # Short object file path will be enabled by default.
    write_to_bazelrc('build --experimental_shortened_obj_file_path=true')
  
    if get_var(
        environ_cp, 'TF_OVERRIDE_EIGEN_STRONG_INLINE', 'Eigen strong inline',
        True, ('Would you like to override eigen strong inline for some C++ '
               'compilation to reduce the compilation time?'),
        'Eigen strong inline overridden.', 'Not overriding eigen strong inline, '
        'some compilations could take more than 20 mins.'):
      # Due to a known MSVC compiler issue
      # https://github.com/tensorflow/tensorflow/issues/10521
      # Overriding eigen strong inline speeds up the compiling of
      # conv_grad_ops_3d.cc and conv_ops_3d.cc by 20 minutes,
      # but this also hurts the performance. Let users decide what they want.
      write_to_bazelrc('build --define=override_eigen_strong_inline=true')
  
  
  def config_info_line(name, help_text):
    """Helper function to print formatted help text for Bazel config options."""
    print('\t--config=%-12s\t# %s' % (name, help_text))
  
  
  def main():
    global _TF_WORKSPACE_ROOT
    global _TF_BAZELRC
  
    parser = argparse.ArgumentParser()
    parser.add_argument(
        '--workspace',
        type=str,
        default=os.path.abspath(os.path.dirname(__file__)),
        help='The absolute path to your active Bazel workspace.')
    args = parser.parse_args()
  
    _TF_WORKSPACE_ROOT = args.workspace
    _TF_BAZELRC = os.path.join(_TF_WORKSPACE_ROOT, _TF_BAZELRC_FILENAME)
  
    # Make a copy of os.environ to be clear when functions and getting and setting
    # environment variables.
    environ_cp = dict(os.environ)
  
    check_bazel_version('0.15.0')
  
    reset_tf_configure_bazelrc()
    cleanup_makefile()
    setup_python(environ_cp)
  
    if is_windows():
      environ_cp['TF_NEED_OPENCL_SYCL'] = '0'
      environ_cp['TF_NEED_COMPUTECPP'] = '0'
      environ_cp['TF_NEED_OPENCL'] = '0'
      environ_cp['TF_CUDA_CLANG'] = '0'
      environ_cp['TF_NEED_TENSORRT'] = '0'
      # TODO(ibiryukov): Investigate using clang as a cpu or cuda compiler on
      # Windows.
      environ_cp['TF_DOWNLOAD_CLANG'] = '0'
      environ_cp['TF_NEED_MPI'] = '0'
      environ_cp['TF_SET_ANDROID_WORKSPACE'] = '0'
  
    if is_macos():
      environ_cp['TF_NEED_TENSORRT'] = '0'
  
    # The numpy package on ppc64le uses OpenBLAS which has multi-threading
    # issues that lead to incorrect answers.  Set OMP_NUM_THREADS=1 at
    # runtime to allow the Tensorflow testcases which compare numpy
    # results to Tensorflow results to succeed.
    if is_ppc64le():
      write_action_env_to_bazelrc('OMP_NUM_THREADS', 1)
  
    xla_enabled_by_default = is_linux()
    set_build_var(environ_cp, 'TF_ENABLE_XLA', 'XLA JIT', 'with_xla_support',
                  xla_enabled_by_default, 'xla')
  
    set_action_env_var(environ_cp, 'TF_NEED_OPENCL_SYCL', 'OpenCL SYCL', False)
    if environ_cp.get('TF_NEED_OPENCL_SYCL') == '1':
      set_host_cxx_compiler(environ_cp)
      set_host_c_compiler(environ_cp)
      set_action_env_var(environ_cp, 'TF_NEED_COMPUTECPP', 'ComputeCPP', True)
      if environ_cp.get('TF_NEED_COMPUTECPP') == '1':
        set_computecpp_toolkit_path(environ_cp)
      else:
        set_trisycl_include_dir(environ_cp)
  
    set_action_env_var(environ_cp, 'TF_NEED_ROCM', 'ROCm', False)
    if (environ_cp.get('TF_NEED_ROCM') == '1' and
        'LD_LIBRARY_PATH' in environ_cp and
        environ_cp.get('LD_LIBRARY_PATH') != '1'):
      write_action_env_to_bazelrc('LD_LIBRARY_PATH',
                                  environ_cp.get('LD_LIBRARY_PATH'))
  
    set_action_env_var(environ_cp, 'TF_NEED_CUDA', 'CUDA', False)
    if (environ_cp.get('TF_NEED_CUDA') == '1' and
        'TF_CUDA_CONFIG_REPO' not in environ_cp):
      set_tf_cuda_version(environ_cp)
      set_tf_cudnn_version(environ_cp)
      if is_linux():
        set_tf_tensorrt_install_path(environ_cp)
        set_tf_nccl_install_path(environ_cp)
  
      set_tf_cuda_compute_capabilities(environ_cp)
      if 'LD_LIBRARY_PATH' in environ_cp and environ_cp.get(
          'LD_LIBRARY_PATH') != '1':
        write_action_env_to_bazelrc('LD_LIBRARY_PATH',
                                    environ_cp.get('LD_LIBRARY_PATH'))
  
      set_tf_cuda_clang(environ_cp)
      if environ_cp.get('TF_CUDA_CLANG') == '1':
        # Ask whether we should download the clang toolchain.
        set_tf_download_clang(environ_cp)
        if environ_cp.get('TF_DOWNLOAD_CLANG') != '1':
          # Set up which clang we should use as the cuda / host compiler.
          set_clang_cuda_compiler_path(environ_cp)
        else:
          # Use downloaded LLD for linking.
          write_to_bazelrc('build:cuda_clang --config=download_clang_use_lld')
          write_to_bazelrc('test:cuda_clang --config=download_clang_use_lld')
      else:
        # Set up which gcc nvcc should use as the host compiler
        # No need to set this on Windows
        if not is_windows():
          set_gcc_host_compiler_path(environ_cp)
      set_other_cuda_vars(environ_cp)
    else:
      # CUDA not required. Ask whether we should download the clang toolchain and
      # use it for the CPU build.
      set_tf_download_clang(environ_cp)
      if environ_cp.get('TF_DOWNLOAD_CLANG') == '1':
        write_to_bazelrc('build --config=download_clang')
        write_to_bazelrc('test --config=download_clang')
  
    # SYCL / ROCm / CUDA are mutually exclusive.
    # At most 1 GPU platform can be configured.
    gpu_platform_count = 0
    if environ_cp.get('TF_NEED_OPENCL_SYCL') == '1':
      gpu_platform_count += 1
    if environ_cp.get('TF_NEED_ROCM') == '1':
      gpu_platform_count += 1
    if environ_cp.get('TF_NEED_CUDA') == '1':
      gpu_platform_count += 1
    if gpu_platform_count >= 2:
      raise UserInputError('SYCL / CUDA / ROCm are mututally exclusive. '
                           'At most 1 GPU platform can be configured.')
  
    set_build_var(environ_cp, 'TF_NEED_MPI', 'MPI', 'with_mpi_support', False)
    if environ_cp.get('TF_NEED_MPI') == '1':
      set_mpi_home(environ_cp)
      set_other_mpi_vars(environ_cp)
  
    set_cc_opt_flags(environ_cp)
    set_system_libs_flag(environ_cp)
    if is_windows():
      set_windows_build_flags(environ_cp)
  
    # Add a config option to build TensorFlow 2.0 API.
    write_to_bazelrc('build:v2 --define=tf_api_version=2')
  
    if get_var(environ_cp, 'TF_SET_ANDROID_WORKSPACE', 'android workspace', False,
               ('Would you like to interactively configure ./WORKSPACE for '
                'Android builds?'), 'Searching for NDK and SDK installations.',
               'Not configuring the WORKSPACE for Android builds.'):
      create_android_ndk_rule(environ_cp)
      create_android_sdk_rule(environ_cp)
  
    print('Preconfigured Bazel build configs. You can use any of the below by '
          'adding "--config=<>" to your build command. See .bazelrc for more '
          'details.')
    config_info_line('mkl', 'Build with MKL support.')
    config_info_line('monolithic', 'Config for mostly static monolithic build.')
    config_info_line('gdr', 'Build with GDR support.')
    config_info_line('verbs', 'Build with libverbs support.')
    config_info_line('ngraph', 'Build with Intel nGraph support.')
    config_info_line('dynamic_kernels',
                     '(Experimental) Build kernels into separate shared objects.')
  
    print('Preconfigured Bazel build configs to DISABLE default on features:')
    config_info_line('noaws', 'Disable AWS S3 filesystem support.')
    config_info_line('nogcp', 'Disable GCP support.')
    config_info_line('nohdfs', 'Disable HDFS support.')
    config_info_line('noignite', 'Disable Apacha Ignite support.')
    config_info_line('nokafka', 'Disable Apache Kafka support.')
  
  
  if __name__ == '__main__':
    main()
  