write_buildflag_header.py

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#!/usr/bin/env python

# Copyright 2015 The Chromium Authors. All rights reserved.

# Use of this source code is governed by a BSD-style license that can be

# found in the LICENSE file.

# This writes headers for build flags. See buildflag_header.gni for usage of

# this system as a whole.

# The parameters are passed in a response file so we don't have to worry

# about command line lengths. The name of the response file is passed on the

# command line.

# The format of the response file is:

#    [--flags <list of one or more flag values>]

import optparse

import os

import shlex

import sys

class Options:

  def __init__(self, output, rulename, header_guard, flags):

    self.output = output

    self.rulename = rulename

    self.header_guard = header_guard

    self.flags = flags

def GetOptions():

  parser = optparse.OptionParser()

  parser.add_option('--output', help="Output header name inside --gen-dir.")

  parser.add_option('--rulename',

                    help="Helpful name of build rule for including in the " +

                         "comment at the top of the file.")

  parser.add_option('--gen-dir',

                    help="Path to root of generated file directory tree.")

  parser.add_option('--definitions',

                    help="Name of the response file containing the flags.")

  cmdline_options, cmdline_flags = parser.parse_args()

  # Compute header guard by replacing some chars with _ and upper-casing.

  header_guard = cmdline_options.output.upper()

  header_guard = \

      header_guard.replace('/', '_').replace('\\', '_').replace('.', '_')

  header_guard += '_'

  # The actual output file is inside the gen dir.

  output = os.path.join(cmdline_options.gen_dir, cmdline_options.output)

  # Definition file in GYP is newline separated, in GN they are shell formatted.

  # shlex can parse both of these.

  with open(cmdline_options.definitions, 'r') as def_file:

    defs = shlex.split(def_file.read())

  flags_index = defs.index('--flags')

  # Everything after --flags are flags. true/false are remapped to 1/0,

  # everything else is passed through.

  flags = []

  for flag in defs[flags_index + 1 :]:

    equals_index = flag.index('=')

    key = flag[:equals_index]

    value = flag[equals_index + 1:]

    # Canonicalize and validate the value.

    if value == 'true':

      value = '1'

    elif value == 'false':

      value = '0'

    flags.append((key, str(value)))

  return Options(output=output,

                 rulename=cmdline_options.rulename,

                 header_guard=header_guard,

                 flags=flags)

def WriteHeader(options):

  with open(options.output, 'w') as output_file:

    output_file.write("// Generated by build/write_buildflag_header.py\n")

    if options.rulename:

      output_file.write('// From "' + options.rulename + '"\n')

    output_file.write('\n#ifndef %s\n' % options.header_guard)

    output_file.write('#define %s\n\n' % options.header_guard)

    output_file.write('#include "build/buildflag.h"\n\n')

    for pair in options.flags:

      output_file.write('#define BUILDFLAG_INTERNAL_%s() (%s)\n' % pair)

    output_file.write('\n#endif  // %s\n' % options.header_guard)

if os.name == 'nt':

  major, minor, build, platform, service_pack = sys.getwindowsversion()

  # Windows 10 will be 6.2 on Python 2 and 10.0 on Python 3. This check

  # handles both.

  if major < 6 or (major == 6 and minor < 2):

    raise Exception(

        'Unsupported OS. Building Chromium requires Windows 10. %s detected.' %

        str(sys.getwindowsversion()))

options = GetOptions()

WriteHeader(options)