Do not sudo unless necessary.

trace_inputs.py

 #!/usr/bin/env python
 # coding=utf-8
 # Copyright (c) 2012 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.
 
 """Traces an executable and its child processes and extract the files accessed
 by them.
 
 The implementation uses OS-specific API. The native Kernel logger and the ETL
 interface is used on Windows. Dtrace is used on OSX. Strace is used otherwise.
 The OS-specific implementation is hidden in an 'API' interface.
 
 The results are embedded in a Results instance. The tracing is done in two
 phases, the first is to do the actual trace and generate an
 implementation-specific log file. Then the log file is parsed to extract the
 information, including the individual child processes and the files accessed
 from the log.
 """
 
 import codecs
 import csv
 import getpass
 import glob
 import json
 import logging
-import unicodedata
 import optparse
 import os
 import re
+import stat
 import subprocess
 import sys
 import tempfile
 import threading
 import time
+import unicodedata
 import weakref
 
 ## OS-specific imports
 
 if sys.platform == 'win32':
   from ctypes.wintypes import byref, create_unicode_buffer, c_int, c_wchar_p
   from ctypes.wintypes import windll, FormatError  # pylint: disable=E0611
   from ctypes.wintypes import GetLastError  # pylint: disable=E0611
 elif sys.platform == 'darwin':
   import Carbon.File  #  pylint: disable=F0401
@@ skipping 2194 matching lines @@
       this needs to wait for dtrace to be "warmed up".
       """
       super(Dtrace.Tracer, self).__init__(logname)
       self._script = create_thunk()
       # This unique dummy temp file is used to signal the dtrace script that it
       # should stop as soon as all the child processes are done. A bit hackish
       # but works fine enough.
       self._dummy_file_id, self._dummy_file_name = tempfile.mkstemp(
           prefix='trace_signal_file')
 
+      dtrace_path = '/usr/sbin/dtrace'
+      if not os.path.isfile(dtrace_path):
+        dtrace_path = 'dtrace'
+      elif use_sudo is None and (os.stat(dtrace_path).st_mode & stat.S_ISUID):
+        # No need to sudo. For those following at home, don't do that.
+        use_sudo = False
+
       # Note: do not use the -p flag. It's useless if the initial process quits
       # too fast, resulting in missing traces from the grand-children. The D
       # code manages the dtrace lifetime itself.
       trace_cmd = [
-        'dtrace',
+        dtrace_path,
         # Use a larger buffer if getting 'out of scratch space' errors.
         # Ref: https://wikis.oracle.com/display/DTrace/Options+and+Tunables
         '-b', '10m',
         '-x', 'dynvarsize=10m',
         #'-x', 'dtrace_global_maxsize=1m',
         '-x', 'evaltime=exec',
         '-o', '/dev/stderr',
         '-q',
         '-n', self._get_dtrace_code(),
       ]
@@ skipping 1302 matching lines @@
     main_impl(argv)
   except TracingFailure, e:
     sys.stderr.write('\nError: ')
     sys.stderr.write(str(e))
     sys.stderr.write('\n')
     return 1
 
 
 if __name__ == '__main__':
   sys.exit(main(sys.argv[1:]))