Install a signal handler to ensure drt-trampoline.py cleans up after itself.

dart/tools/testing/drt-trampoline.py

 # Copyright (c) 2011, the Dart project authors.  Please see the AUTHORS file
 # for details. All rights reserved. Use of this source code is governed by a
 # BSD-style license that can be found in the LICENSE file.
 #
 # For now we have to use this trampoline to turn --dart-flags command line
 # switch into env variable DART_FLAGS.  Eventually, DumpRenderTree should
 # support --dart-flags and this hack may go away.
 #
 # Expected invocation: python drt-trampoline.py <path to DRT> <DRT command line>
 
 import os
+import signal
 import subprocess
 import sys
 
 DART_FLAGS_PREFIX = '--dart-flags='
 OUT_EXPECTATION_PREFIX = '--out-expectation='
 
 def main(argv):
   drt_path = argv[1]
   command_line = argv[2:]
 
@@ skipping 24 matching lines @@
       cmd.append(arg)
 
   if is_png:
     # pixel tests are specified by running DRT "foo.html'-p"
     cmd.append(test_file + "'-p")
   else:
     cmd.append(test_file)
 
   stdout = subprocess.PIPE if out_expected_file else None
   p = subprocess.Popen(cmd, env=env, stdout=stdout)
+
+  def signal_handler(signal, frame):
+    p.terminate()
+    sys.exit(0)
+
+  # SIGINT is Ctrl-C.
+  signal.signal(signal.SIGINT, signal_handler)
+  # SIGTERM is sent by test.dart when a process times out.
+  signal.signal(signal.SIGTERM, signal_handler)
   output, error = p.communicate()
+  signal.signal(signal.SIGINT, signal.SIG_DFL)
+  signal.signal(signal.SIGTERM, signal.SIG_DFL)
+
   if p.returncode != 0:
     raise Exception('Failed to run command. return code=%s' % p.returncode)
 
   if out_expected_file:
     # Compare output to the given expectation file.
     expectation = None
     if is_png:
       # DRT prints the image to STDOUT, but includes extra text that we trim:
       # - several header lines until a line saying 'Content-Length:'
       # - a '#EOF\n' at the end
@@ skipping 28 matching lines @@
       print 'You can update expectations by running:\n'
       print 'cp %s %s\n' % (out_file, out_expected_file)
     print '#EOF'
 
 if __name__ == '__main__':
   try:
     sys.exit(main(sys.argv))
   except StandardError as e:
     print 'Fail: ' + str(e)
     sys.exit(1)