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1#!/bin/bash
2
3# Copyright (c) 2012 The Chromium Authors. All rights reserved.
4# Use of this source code is governed by a BSD-style license that can be
5# found in the LICENSE file.
6
7# Usage: make_more_helpers.sh <directory_within_contents> <app_name>
8#
9# This script creates additional helper .app bundles for Chromium, based on
10# the existing helper .app bundle, changing their Mach-O header's flags to
11# enable and disable various features. Based on Chromium Helper.app, it will
12# create Chromium Helper EH.app, which has the MH_NO_HEAP_EXECUTION bit
13# cleared to support Chromium child processes that require an executable heap,
14# and Chromium Helper NP.app, which has the MH_PIE bit cleared to support
15# Chromium child processes that cannot tolerate ASLR.
16#
17# This script expects to be called from the chrome_exe target as a postbuild,
18# and operates directly within the built-up browser app's versioned directory.
19#
20# Each helper is adjusted by giving it the proper bundle name, renaming the
21# executable, adjusting several Info.plist keys, and changing the executable's
22# Mach-O flags.
23
24set -eu
25
26make_helper() {
27  local containing_dir="${1}"
28  local app_name="${2}"
29  local feature="${3}"
30  local flags="${4}"
31
32  local helper_name="${app_name} Helper"
33  local helper_stem="${containing_dir}/${helper_name}"
34  local original_helper="${helper_stem}.app"
35  if [[ ! -d "${original_helper}" ]]; then
36    echo "${0}: error: ${original_helper} is a required directory" >& 2
37    exit 1
38  fi
39  local original_helper_exe="${original_helper}/Contents/MacOS/${helper_name}"
40  if [[ ! -f "${original_helper_exe}" ]]; then
41    echo "${0}: error: ${original_helper_exe} is a required file" >& 2
42    exit 1
43  fi
44
45  local feature_helper="${helper_stem} ${feature}.app"
46
47  rsync -acC --delete --include '*.so' "${original_helper}/" "${feature_helper}"
48
49  local helper_feature="${helper_name} ${feature}"
50  local helper_feature_exe="${feature_helper}/Contents/MacOS/${helper_feature}"
51  mv "${feature_helper}/Contents/MacOS/${helper_name}" "${helper_feature_exe}"
52
53  local change_flags="$(dirname "${0}")/change_mach_o_flags.py"
54  "${change_flags}" ${flags} "${helper_feature_exe}"
55
56  local feature_info="${feature_helper}/Contents/Info"
57  local feature_info_plist="${feature_info}.plist"
58
59  defaults write "${feature_info}" "CFBundleDisplayName" "${helper_feature}"
60  defaults write "${feature_info}" "CFBundleExecutable" "${helper_feature}"
61
62  cfbundleid="$(defaults read "${feature_info}" "CFBundleIdentifier")"
63  feature_cfbundleid="${cfbundleid}.${feature}"
64  defaults write "${feature_info}" "CFBundleIdentifier" "${feature_cfbundleid}"
65
66  cfbundlename="$(defaults read "${feature_info}" "CFBundleName")"
67  feature_cfbundlename="${cfbundlename} ${feature}"
68  defaults write "${feature_info}" "CFBundleName" "${feature_cfbundlename}"
69
70  # As usual, defaults might have put the plist into whatever format excites
71  # it, but Info.plists get converted back to the expected XML format.
72  plutil -convert xml1 "${feature_info_plist}"
73
74  # `defaults` also changes the file permissions, so make the file
75  # world-readable again.
76  chmod a+r "${feature_info_plist}"
77}
78
79if [[ ${#} -ne 2 ]]; then
80  echo "usage: ${0} <directory_within_contents> <app_name>" >& 2
81  exit 1
82fi
83
84DIRECTORY_WITHIN_CONTENTS="${1}"
85APP_NAME="${2}"
86
87CONTENTS_DIR="${BUILT_PRODUCTS_DIR}/${CONTENTS_FOLDER_PATH}"
88CONTAINING_DIR="${CONTENTS_DIR}/${DIRECTORY_WITHIN_CONTENTS}"
89
90make_helper "${CONTAINING_DIR}" "${APP_NAME}" "EH" "--executable-heap"
91make_helper "${CONTAINING_DIR}" "${APP_NAME}" "NP" "--no-pie"
92