check_static_initializers should use hermetic xcode paths

Both `otool` and `atos` commands needed to be run with the hermetic
xcode paths. The code will first check that the hermetic xcode paths
exists before using that path.

Bug: 1113466
Change-Id: I11304f1981faf55946d3aa6fde44af631c87dc3a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2340795
Commit-Queue: Stephanie Kim <kimstephanie@google.com>
Reviewed-by: Nico Weber <thakis@chromium.org>
Cr-Commit-Position: refs/heads/master@{#799292}

testing/scripts/check_static_initializers.py

@@ -68,7 +68,19 @@ def main_mac(src_dir):
       # Count the number of files with at least one static initializer.
       si_count = 0
       # Find the __DATA,__mod_init_func section.
-      stdout = run_process(['otool', '-l', chromium_framework_executable])
+
+      # If the checkout uses the hermetic xcode binaries, then otool must be
+      # directly invoked. The indirection via /usr/bin/otool won't work unless
+      # there's an actual system install of Xcode.
+      hermetic_xcode_path = os.path.join(src_dir, 'build', 'mac_files',
+          'xcode_binaries')
+      if os.path.exists(hermetic_xcode_path):
+        otool_path = os.path.join(hermetic_xcode_path, 'Contents', 'Developer',
+            'Toolchains', 'XcodeDefault.xctoolchain', 'usr', 'bin', 'otool')
+      else:
+        otool_path = 'otool'
+
+      stdout = run_process([otool_path, '-l', chromium_framework_executable])
       section_index = stdout.find('sectname __mod_init_func')
       if section_index != -1:
         # If the section exists, the "size" line must follow it.
@@ -106,6 +118,10 @@ def main_mac(src_dir):
           else:
             print '# Warning: Falling back to potentially stripped output.'
             args.append(chromium_framework_executable)
+
+          if os.path.exists(hermetic_xcode_path):
+            args.extend(['--xcode-path', hermetic_xcode_path])
+
           stdout = run_process(args)
           print stdout
   return ret

tools/mac/show_mod_init_func.py

@@ -17,31 +17,37 @@ dump-static-initializers.py instead.
 from __future__ import print_function
 
 import optparse
+import os
 import subprocess
 import sys
 
 
-def ShowModuleInitializers(binary):
+def ShowModuleInitializers(binary, xcode_path):
   """Gathers the module initializers for |binary| and symbolizes the addresses.
   """
-  initializers = GetModuleInitializers(binary)
+  initializers = GetModuleInitializers(binary, xcode_path)
   if not initializers:
     # atos will do work even if there are no addresses, so bail early.
     return
-  symbols = SymbolizeAddresses(binary, initializers)
+  symbols = SymbolizeAddresses(binary, initializers, xcode_path)
 
   print(binary)
   for initializer in zip(initializers, symbols):
     print('%s @ %s' % initializer)
 
 
-def GetModuleInitializers(binary):
+def GetModuleInitializers(binary, xcode_path):
   """Parses the __DATA,__mod_init_func segment of |binary| and returns a list
   of string hexadecimal addresses of the module initializers.
   """
+  if xcode_path:
+    otool_path = os.path.join(xcode_path, 'Contents', 'Developer',
+        'Toolchains', 'XcodeDefault.xctoolchain', 'usr', 'bin', 'otool')
+  else:
+    otool_path = 'otool'
   # The -v flag will display the addresses in a usable form (as opposed to
   # just its on-disk little-endian byte representation).
-  otool = ['otool', '-v', '-s', '__DATA', '__mod_init_func', binary]
+  otool = [otool_path, '-v', '-s', '__DATA', '__mod_init_func', binary]
   lines = subprocess.check_output(otool).strip().split('\n')
 
   # Skip the first two header lines and then get the address of the
@@ -53,22 +59,34 @@ def GetModuleInitializers(binary):
   return [line.split(' ')[1] for line in lines[2:]]
 
 
-def SymbolizeAddresses(binary, addresses):
+def SymbolizeAddresses(binary, addresses, xcode_path):
   """Given a |binary| and a list of |addresses|, symbolizes them using atos.
   """
-  atos = ['xcrun', 'atos', '-o', binary] + addresses
+  if xcode_path:
+    atos_path = os.path.join(xcode_path, 'Contents', 'Developer', 'usr',
+        'bin', 'atos')
+  else:
+    atos_path = 'atos'
+
+  atos = [atos_path, '-o', binary] + addresses
   lines = subprocess.check_output(atos).strip().split('\n')
   return lines
 
 
 def Main():
   parser = optparse.OptionParser(usage='%prog filename')
+  parser.add_option(
+      '--xcode-path',
+      default=None,
+      help='Optional custom path to xcode binaries. By default, commands such '
+      'as `otool` will be run as `/usr/bin/otool` which only works '
+      'if there is a system-wide install of Xcode.')
   opts, args = parser.parse_args()
   if len(args) != 1:
     parser.error('missing binary filename')
     return 1
 
-  ShowModuleInitializers(args[0])
+  ShowModuleInitializers(args[0], opts.xcode_path)
   return 0
 
 if __name__ == '__main__':