Fixed issue 401: os.system() hangs on Mac OS X.

src/d8-posix.cc

 // Copyright 2009 the V8 project authors. All rights reserved.
 // Redistribution and use in source and binary forms, with or without
 // modification, are permitted provided that the following conditions are
 // met:
 //
 //     * Redistributions of source code must retain the above copyright
 //       notice, this list of conditions and the following disclaimer.
 //     * Redistributions in binary form must reproduce the above
 //       copyright notice, this list of conditions and the following
 //       disclaimer in the documentation and/or other materials provided
@@ skipping 352 matching lines @@
   return accumulator;
 }
 
 
 // Modern Linux has the waitid call, which is like waitpid, but more useful
 // if you want a timeout.  If we don't have waitid we can't limit the time
 // waiting for the process to exit without losing the information about
 // whether it exited normally.  In the common case this doesn't matter because
 // we don't get here before the child has closed stdout and most programs don't
 // do that before they exit.
-#if defined(WNOWAIT) && !defined(ANDROID)
+//
+// We're disabling usage of waitid in Mac OS X because it doens't work for us:
+// a parent process hangs on waiting while a child process is already a zombie.
+// See http://code.google.com/p/v8/issues/detail?id=401.
+#if defined(WNOWAIT) && !defined(ANDROID) && !defined(__APPLE__)
 #define HAS_WAITID 1
 #endif
 
 
 // Get exit status of child.
 static bool WaitForChild(int pid,
                          ZombieProtector& child_waiter,
                          struct timeval& start_time,
                          int read_timeout,
                          int total_timeout) {
@@ skipping 278 matching lines @@
 void Shell::AddOSMethods(Handle<ObjectTemplate> os_templ) {
   os_templ->Set(String::New("system"), FunctionTemplate::New(System));
   os_templ->Set(String::New("chdir"), FunctionTemplate::New(ChangeDirectory));
   os_templ->Set(String::New("setenv"), FunctionTemplate::New(SetEnvironment));
   os_templ->Set(String::New("umask"), FunctionTemplate::New(SetUMask));
   os_templ->Set(String::New("mkdirp"), FunctionTemplate::New(MakeDirectory));
   os_templ->Set(String::New("rmdir"), FunctionTemplate::New(RemoveDirectory));
 }
 
 }  // namespace v8