build/mac/verify_no_objc.sh

   1 #!/bin/bash
   2
   3 # Copyright (c) 2011 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 # This script makes sure that no __OBJC,__image_info section appears in the
   8 # executable file built by the Xcode target that runs the script. If such a
   9 # section appears, the script prints an error message and exits nonzero.
  10 #
  11 # Why is this important?
  12 #
  13 # On 10.5, there's a bug in CFBundlePreflightExecutable that causes it to
  14 # crash when operating in an executable that has not loaded at its default
  15 # address (that is, when it's a position-independent executable with the
  16 # MH_PIE bit set in its mach_header) and the executable has an
  17 # __OBJC,__image_info section. See http://crbug.com/88697.
  18 #
  19 # Chrome's main executables don't use any Objective-C at all, and don't need
  20 # to carry this section around. Not linking them as Objective-C when they
  21 # don't need it anyway saves about 4kB in the linked executable, although most
  22 # of that 4kB is just filled with zeroes.
  23 #
  24 # This script makes sure that nobody goofs and accidentally introduces these
  25 # sections into the main executables.
  26
  27 set -eu
  28
  29 executable="${BUILT_PRODUCTS_DIR}/${EXECUTABLE_PATH}"
  30
  31 if xcrun otool -arch i386 -o "${executable}" | grep -q '^Contents.*section$'; \
  32 then
  33   echo "${0}: ${executable} has an __OBJC,__image_info section" 2>&1
  34   exit 1
  35 fi
  36
  37 if [[ ${PIPESTATUS[0]} -ne 0 ]]; then
  38   echo "${0}: otool failed" 2>&1
  39   exit 1
  40 fi
  41
  42 exit 0