Fast release builds

build/mac/strip_save_dsym

+#!/usr/bin/python
+
+# Copyright (c) 2008 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: strip_save_dsym <whatever-arguments-you-would-pass-to-strip>
+#
+# strip_save_dsym is a wrapper around the standard strip utility.  Given an
+# input Mach-O file, strip_save_dsym will save a copy of the file in a "fake"
+# .dSYM bundle for debugging, and then call strip to strip the Mach-O file.
+# Note that the .dSYM file is a "fake" in that it's not a self-contained
+# .dSYM bundle, it just contains a copy of the original (unstripped) Mach-O
+# file, and therefore contains references to object files on the filesystem.
+# The generated .dSYM bundle is therefore unsuitable for debugging in the
+# absence of these .o files.
+#
+# If a .dSYM already exists and has a newer timestamp than the Mach-O file,
+# this utility does nothing.  That allows strip_save_dsym to be run on a file
+# that has already been stripped without trashing the .dSYM.
+#
+# Rationale: the "right" way to generate dSYM bundles, dsymutil, is incredibly
+# slow.  On the other hand, doing a file copy (which is really all that
+# dsymutil does) is comparatively fast.  Since we usually just want to strip
+# a release-mode executable but still be able to debug it, and we don't care
+# so much about generating a hermetic dSYM bundle, we'll prefer the file copy.
+# If a real dSYM is ever needed, it's still possible to create one by running
+# dsymutil and pointing it at the original Mach-O file inside the "fake"
+# bundle, provided that the object files are available.
+
+import errno
+import os
+import re
+import shutil
+import subprocess
+import sys
+import time
+
+# Returns a list of architectures contained in a Mach-O file.  The file can be
+# a universal (fat) file, in which case there will be one list element for
+# each contained architecture, or it can be a thin single-architecture Mach-O
+# file, in which case the list will contain a single element identifying the
+# architecture.  On error, returns an empty list.  Determines the architecture
+# list by calling file.
+def macho_archs(macho):
+  file_cmd = subprocess.Popen(["/usr/bin/file", "-b", "--", macho],
+                              stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+
+  archs = []
+
+  type_line = file_cmd.stdout.readline()
+  type_match = re.match("^Mach-O executable (.*)$", type_line)
+  if type_match:
+    archs.append(type_match.group(1))
+    return [type_match.group(1)]
+  else:
+    type_match = re.match("^Mach-O universal binary with (.*) architectures$",
+                          type_line)
+    if type_match:
+      for i in range(0, int(type_match.group(1))):
+        arch_line = file_cmd.stdout.readline()
+        arch_match = re.match(
+                     "^.* \(for architecture (.*)\):\tMach-O executable .*$",
+                     arch_line)
+        if arch_match:
+          archs.append(arch_match.group(1))
+
+  if file_cmd.wait() != 0:
+    archs = []
+
+  return archs
+
+# Returns a dictionary mapping architectures contained in the file as returned
+# by macho_archs to the LC_UUID load command for that architecture.
+# Architectures with no LC_UUID load command are omitted from the dictionary.
+# Determines the UUID value by calling otool.
+def macho_uuids(macho):
+  archs = macho_archs(macho)
+
+  uuids = {} 
+
+  for arch in archs:
+    if arch == "":
+      continue
+
+    otool_cmd = subprocess.Popen(["/usr/bin/otool", "-arch", arch, "-l", "-",
+                                  macho],
+                                 stdout=subprocess.PIPE, stderr=subprocess.PIPE)
+    # state 0 is when nothing UUID-related has been seen yet.  State 1 is
+    # entered after a load command begins, but it may not be an LC_UUID load
+    # command.  States 2, 3, and 4 are intermediate states while reading an
+    # LC_UUID command.  State 5 is the terminal state for a successful LC_UUID
+    # read.  State 6 is the error state.
+    state = 0
+    uuid = ""
+    for otool_line in otool_cmd.stdout:
+      if state == 0:
+        if re.match("^Load command .*$", otool_line):
+          state = 1
+      elif state == 1:
+        if re.match("^     cmd LC_UUID$", otool_line):
+          state = 2
+        else:
+          state = 0
+      elif state == 2:
+        if re.match("^ cmdsize 24$", otool_line):
+          state = 3
+        else:
+          state = 6
+      elif state == 3:
+        uuid_match = re.match("^   uuid 0x(..) 0x(..) 0x(..) 0x(..) "
+                              "0x(..) 0x(..) 0x(..) 0x(..)$",
+                              otool_line)
+        if uuid_match:
+          state = 4
+          uuid = uuid_match.group(1) + uuid_match.group(2) + \
+                 uuid_match.group(3) + uuid_match.group(4) + "-" + \
+                 uuid_match.group(5) + uuid_match.group(6) + "-" + \
+                 uuid_match.group(7) + uuid_match.group(8) + "-"
+        else:
+          state = 6
+      elif state == 4:
+        uuid_match = re.match("^        0x(..) 0x(..) 0x(..) 0x(..) "
+                              "0x(..) 0x(..) 0x(..) 0x(..)$",
+                              otool_line)
+        if uuid_match:
+          state = 5
+          uuid += uuid_match.group(1) + uuid_match.group(2) + "-" + \
+                  uuid_match.group(3) + uuid_match.group(4) + \
+                  uuid_match.group(5) + uuid_match.group(6) + \
+                  uuid_match.group(7) + uuid_match.group(8)
+        else:
+          state = 6
+
+    if otool_cmd.wait() != 0:
+      state = 6
+
+    if state == 5:
+      uuids[arch] = uuid.upper()
+
+  return uuids
+
+# Given a path to a Mach-O file and possible information from the environment,
+# determines the desired path to the .dSYM.
+def dsym_path(macho):
+  # If building a bundle, the .dSYM should be placed next to the bundle.  Use
+  # WRAPPER_NAME to make this determination.  If called from xcodebuild,
+  # WRAPPER_NAME will be set to the name of the bundle.
+  dsym = ""
+  if "WRAPPER_NAME" in os.environ:
+    if "BUILT_PRODUCTS_DIR" in os.environ:
+      dsym = os.path.join(os.environ["BUILT_PRODUCTS_DIR"],
+                          os.environ["WRAPPER_NAME"])
+    else:
+      dsym = os.environ["WRAPPER_NAME"]
+  else:
+    dsym = macho
+
+  dsym += ".dSYM"
+
+  return dsym
+
+# Creates a fake .dSYM bundle at dsym for macho, a Mach-O image with the
+# architectures and UUIDs specified by the uuids map.
+def make_fake_dsym(macho, dsym):
+  uuids = macho_uuids(macho)
+  if len(uuids) == 0:
+    return False
+
+  dwarf_dir = os.path.join(dsym, "Contents", "Resources", "DWARF")
+  dwarf_file = os.path.join(dwarf_dir, os.path.basename(macho))
+  try:
+    os.makedirs(dwarf_dir)
+  except OSError, (err, error_string):
+    if err != errno.EEXIST:
+      raise
+  shutil.copyfile(macho, dwarf_file)
+
+  # info_template is the same as what dsymutil would have written, with the
+  # addition of the fake_dsym key.
+  info_template = \
+'''<?xml version="1.0" encoding="UTF-8"?>
+<!DOCTYPE plist PUBLIC "-//Apple Computer//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
+<plist version="1.0">
+        <dict>
+                <key>CFBundleDevelopmentRegion</key>
+                <string>English</string>
+                <key>CFBundleIdentifier</key>
+                <string>com.apple.xcode.dsym.%(root_name)s</string>
+                <key>CFBundleInfoDictionaryVersion</key>
+                <string>6.0</string>
+                <key>CFBundlePackageType</key>
+                <string>dSYM</string>
+                <key>CFBundleSignature</key>
+                <string>????</string>
+                <key>CFBundleShortVersionString</key>
+                <string>1.0</string>
+                <key>CFBundleVersion</key>
+                <string>1</string>
+                <key>dSYM_UUID</key>
+                <dict>
+%(uuid_dict)s           </dict>
+                <key>fake_dsym</key>
+                <true/>
+        </dict>
+</plist>
+'''
+
+  root_name = os.path.basename(dsym)[:-5]  # whatever.dSYM without .dSYM
+  uuid_dict = ""
+  for arch in sorted(uuids):
+    uuid_dict += "\t\t\t<key>" + arch + "</key>\n"\
+                 "\t\t\t<string>" + uuids[arch] + "</string>\n"
+  info_dict = {
+    "root_name": root_name,
+    "uuid_dict": uuid_dict,
+  }
+  info_contents = info_template % info_dict
+  info_file = os.path.join(dsym, "Info.plist")
+  info_fd = open(info_file, "w")
+  info_fd.write(info_contents)
+  info_fd.close()
+
+  return True
+
+# For a Mach-O file, determines where the .dSYM bundle should be located.  If
+# the bundle does not exist or has a modification time older than the Mach-O
+# file, calls make_fake_dsym to create a fake .dSYM bundle there, then strips
+# the Mach-O file and sets the modification time on the .dSYM bundle and Mach-O
+# file to be identical.
+def strip_and_make_fake_dsym(macho):
+  dsym = dsym_path(macho)
+  macho_stat = os.stat(macho)
+  dsym_stat = None
+  try:
+    dsym_stat = os.stat(dsym)
+  except OSError, (err, error_string):
+    if err != errno.ENOENT:
+      raise
+
+  if dsym_stat is None or dsym_stat.st_mtime < macho_stat.st_mtime:
+    # Make a .dSYM bundle
+    if not make_fake_dsym(macho, dsym):
+      return False
+
+    # Strip the Mach-O file
+    remove_dsym = True
+    try:
+      strip_path = ""
+      if "SYSTEM_DEVELOPER_BIN_DIR" in os.environ:
+        strip_path = os.environ["SYSTEM_DEVELOPER_BIN_DIR"]
+      else:
+        strip_path = "/usr/bin"
+      strip_path = os.path.join(strip_path, "strip")
+      strip_cmdline = [strip_path] + sys.argv[1:]
+      # Print the strip invocation so that it's obvious something is happening
+      print " ".join(strip_cmdline)
+      strip_cmd = subprocess.Popen(strip_cmdline)
+      if strip_cmd.wait() == 0:
+        remove_dsym = False
+    finally:
+      if remove_dsym:
+        shutil.rmtree(dsym)
+
+    # Update modification time on the Mach-O file and .dSYM bundle
+    now = time.time()
+    os.utime(macho, (now, now))
+    os.utime(dsym, (now, now))
+
+  return True
+
+def main(argv=None):
+  if argv is None:
+    argv = sys.argv
+
+  # This only supports operating on one file at a time.  Look at the arguments
+  # to strip to figure out what the source to be stripped is.  Arguments are
+  # processed in the same way that strip does, although to reduce complexity,
+  # this doesn't do all of the same checking as strip.  For example, strip
+  # has no -Z switch and would treat -Z on the command line as an error.  For
+  # the purposes this is needed for, that's fine.
+  macho = None
+  process_switches = True
+  ignore_argument = False
+  for arg in argv[1:]:
+    if ignore_argument:
+      ignore_argument = False
+      continue
+    if process_switches:
+      if arg == "-":
+        process_switches = False
+      # strip has these switches accept an argument:
+      if arg in ["-s", "-R", "-d", "-o", "-arch"]:
+        ignore_argument = True
+      if arg[0] == "-":
+        continue
+    if macho is None:
+      macho = arg
+    else:
+      print >> sys.stderr, "Too many things to strip"
+      return 1
+
+  if macho is None:
+    print >> sys.stderr, "Nothing to strip"
+    return 1
+
+  if not strip_and_make_fake_dsym(macho):
+    return 1
+
+  return 0
+
+if __name__ == '__main__':
+  sys.exit(main(sys.argv))