checkbins.py: skip /SAFESEH check on 64-bit Windows binaries

tools/checkbins/checkbins.py

 #!/usr/bin/env python
 # Copyright (c) 2011 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.
 
 """Makes sure that all EXE and DLL files in the provided directory were built
 correctly.
 
 In essense it runs a subset of BinScope tests ensuring that binaries have
 /NXCOMPAT, /DYNAMICBASE and /SAFESEH.
 """
 
 import os
 import optparse
 import sys
 
 # Find /third_party/pefile based on current directory and script path.
 sys.path.append(os.path.join(os.path.dirname(__file__), '..', '..',
                              'third_party', 'pefile'))
 import pefile
 
 PE_FILE_EXTENSIONS = ['.exe', '.dll']
 DYNAMICBASE_FLAG = 0x0040
 NXCOMPAT_FLAG = 0x0100
 NO_SEH_FLAG = 0x0400
+MACHINE_TYPE_AMD64 = 0x8664
 
 # Please do not add your file here without confirming that it indeed doesn't
 # require /NXCOMPAT and /DYNAMICBASE.  Contact cpu@chromium.org or your local
 # Windows guru for advice.
 EXCLUDED_FILES = ['chrome_frame_mini_installer.exe',
                   'mini_installer.exe',
                   'wow_helper.exe']
 
 def IsPEFile(path):
   return (os.path.isfile(path) and
@@ skipping 24 matching lines @@
       print "Checking %s for /DYNAMICBASE... FAIL" % path
 
     # Check for /NXCOMPAT.
     if pe.OPTIONAL_HEADER.DllCharacteristics & NXCOMPAT_FLAG:
       if options.verbose:
         print "Checking %s for /NXCOMPAT... PASS" % path
     else:
       success = False
       print "Checking %s for /NXCOMPAT... FAIL" % path
 
-    # Check for /SAFESEH. Binaries should either have no SEH table
-    # (in which case a bit is set in the DLL characteristics section)
-    # or there should be a LOAD_CONFIG section present containing
-    # a valid SEH table.
+    # Check for /SAFESEH. Binaries should meet one of the following
+    # criteria:
+    #   1) Have no SEH table as indicated by the DLL characteristics
+    #   2) Have a LOAD_CONFIG section containing a valid SEH table
+    #   3) Be a 64-bit binary, in which case /SAFESEH isn't required
+    #
+    # Refer to the following MSDN article for more information:
+    # http://msdn.microsoft.com/en-us/library/9a89h429.aspx
     if (pe.OPTIONAL_HEADER.DllCharacteristics & NO_SEH_FLAG or
         (hasattr(pe, "DIRECTORY_ENTRY_LOAD_CONFIG") and
          pe.DIRECTORY_ENTRY_LOAD_CONFIG.struct.SEHandlerCount > 0 and
-         pe.DIRECTORY_ENTRY_LOAD_CONFIG.struct.SEHandlerTable != 0)):
+         pe.DIRECTORY_ENTRY_LOAD_CONFIG.struct.SEHandlerTable != 0) or
+        pe.FILE_HEADER.Machine == MACHINE_TYPE_AMD64):
       if options.verbose:
         print "Checking %s for /SAFESEH... PASS" % path
     else:
       # TODO(scherkus): uncomment this code after we're confident that we
       # won't cause unintentional failures on the build bots.
       #success = False
       print "Checking %s for /SAFESEH... FAIL" % path
 
     # Update tally.
     if success:
       pe_passed = pe_passed + 1
 
   print "Result: %d files found, %d files passed" % (pe_total, pe_passed)
   if pe_passed != pe_total:
     sys.exit(1)
 
 if __name__ == '__main__':
   usage = "Usage: %prog [options] DIRECTORY"
   option_parser = optparse.OptionParser(usage=usage)
   option_parser.add_option("-v", "--verbose", action="store_true",
                            default=False, help="Print debug logging")
   options, args = option_parser.parse_args()
   if not args:
     option_parser.print_help()
     sys.exit(0)
   main(options, args)