#!/bin/bash

# Copyright (c) 2012 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.

# Usage: make_more_helpers.sh <directory_within_contents> <app_name>
#
# This script creates additional helper .app bundles for Chromium, based on
# the existing helper .app bundle, changing their Mach-O header's flags to
# enable and disable various features. Based on Chromium Helper.app, it will
# create Chromium Helper EH.app, which has the MH_NO_HEAP_EXECUTION bit
# cleared to support Chromium child processes that require an executable heap,
# and Chromium Helper NP.app, which has the MH_PIE bit cleared to support
# Chromium child processes that cannot tolerate ASLR.
#
# This script expects to be called from the chrome_exe target as a postbuild,
# and operates directly within the built-up browser app's versioned directory.
#
# Each helper is adjusted by giving it the proper bundle name, renaming the
# executable, adjusting several Info.plist keys, and changing the executable's
# Mach-O flags.

set -eu

proc make_helper {
  var containing_dir = $(1)
  var app_name = $(2)
  var feature = $(3)
  var flags = $(4)

  var helper_name = ""$(app_name) Helper""
  var helper_stem = ""$(containing_dir)/$(helper_name)""
  var original_helper = ""$(helper_stem).app""
  if [[ ! -d "${original_helper}" ]] {
    echo "$(0): error: $(original_helper) is a required directory" > !2
    exit 1
  }
  var original_helper_exe = ""$(original_helper)/Contents/MacOS/$(helper_name)""
  if [[ ! -f "${original_helper_exe}" ]] {
    echo "$(0): error: $(original_helper_exe) is a required file" > !2
    exit 1
  }

  var feature_helper = ""$(helper_stem) $(feature).app""

  rsync -acC --delete --include '*.so' "$(original_helper)/" $(feature_helper)

  var helper_feature = ""$(helper_name) $(feature)""
  var helper_feature_exe = ""$(feature_helper)/Contents/MacOS/$(helper_feature)""
  mv "$(feature_helper)/Contents/MacOS/$(helper_name)" $(helper_feature_exe)

  var change_flags = ""$[dirname $(0)]/change_mach_o_flags.py""
  $(change_flags) $(flags) $(helper_feature_exe)

  var feature_info = ""$(feature_helper)/Contents/Info""
  var feature_info_plist = ""$(feature_info).plist""

  defaults write $(feature_info) "CFBundleDisplayName" $(helper_feature)
  defaults write $(feature_info) "CFBundleExecutable" $(helper_feature)

  setglobal cfbundleid = $[defaults read $(feature_info) "CFBundleIdentifier]
  setglobal feature_cfbundleid = ""$(cfbundleid).$(feature)""
  defaults write $(feature_info) "CFBundleIdentifier" $(feature_cfbundleid)

  setglobal cfbundlename = $[defaults read $(feature_info) "CFBundleName]
  setglobal feature_cfbundlename = ""$(cfbundlename) $(feature)""
  defaults write $(feature_info) "CFBundleName" $(feature_cfbundlename)

  # As usual, defaults might have put the plist into whatever format excites
  # it, but Info.plists get converted back to the expected XML format.
  plutil -convert xml1 $(feature_info_plist)

  # `defaults` also changes the file permissions, so make the file
  # world-readable again.
  chmod a+r $(feature_info_plist)
}

if [[ ${#} -ne 2 ]] {
  echo "usage: $(0) <directory_within_contents> <app_name>" > !2
  exit 1
}

setglobal DIRECTORY_WITHIN_CONTENTS = $(1)
setglobal APP_NAME = $(2)

setglobal CONTENTS_DIR = ""$(BUILT_PRODUCTS_DIR)/$(CONTENTS_FOLDER_PATH)""
setglobal CONTAINING_DIR = ""$(CONTENTS_DIR)/$(DIRECTORY_WITHIN_CONTENTS)""

make_helper $(CONTAINING_DIR) $(APP_NAME) "EH" "--executable-heap"
make_helper $(CONTAINING_DIR) $(APP_NAME) "NP" "--no-pie"