Better error message for running szbuild.py out of directory.

pydir/utils.py

 import os
 import subprocess
 import sys
 
 def shellcmd(command, echo=True):
     if not isinstance(command, str):
         command = ' '.join(command)
 
     if echo: print '[cmd]', command
 
     stdout_result = subprocess.check_output(command, shell=True)
     if echo: sys.stdout.write(stdout_result)
     return stdout_result
 
 def FindBaseNaCl():
     """Find the base native_client/ directory."""
     nacl = 'native_client'
     path_list = os.getcwd().split(os.sep)
+    """Use the executable path if cwd does not contain 'native_client' """
+    path_list = path_list if nacl in path_list else sys.argv[0].split(os.sep)
     if nacl not in path_list:
-        return None
+        print "Script must be executed from within 'native_client' directory"
+        exit(1)
     last_index = len(path_list) - path_list[::-1].index(nacl)
     return os.sep.join(path_list[:last_index])
 
 def get_sfi_string(args, sb_ret, nonsfi_ret, native_ret):
     """Return a value depending on args.sandbox and args.nonsfi."""
     if args.sandbox:
         assert(not args.nonsfi)
         return sb_ret
     if args.nonsfi:
         return nonsfi_ret
     return native_ret