*NIX ACE_Process::child is unable to call setrlimit after set*id

[likema]

ACE_Process::child is called after for fork and various set*id on UNIX

If calling setrlimit inside ACE_Process::child, setrlimit might return -1 with errno EPERM because various set*id might limit permissions.

See also:

ACE_TAO/ACE/ace/Process.cpp

Lines 383 to 444 in 44c80da

	this->child_id_ = ACE::fork (options.process_name (),
	options.avoid_zombies ());
	if (this->child_id_ == 0)
	{
	# if !defined (ACE_LACKS_SETPGID)
	// If we're the child and the options specified a non-default
	// process group, try to set our pgid to it. This allows the
	// <ACE_Process_Manager> to wait for processes by their
	// process-group.
	if (options.getgroup () != ACE_INVALID_PID
	&& ACE_OS::setpgid (0,
	options.getgroup ()) < 0)
	{
	#if !defined (ACE_HAS_THREADS)
	// We can't emit this log message because ACELIB_ERROR(), etc.
	// will invoke async signal unsafe functions, which results
	// in undefined behavior in threaded programs.
	ACELIB_ERROR ((LM_ERROR,
	ACE_TEXT ("%p.\n"),
	ACE_TEXT ("ACE_Process::spawn: setpgid failed.")));
	#endif
	}
	# endif /* ACE_LACKS_SETPGID */
	# if !defined (ACE_LACKS_SETREGID)
	if (options.getrgid () != (uid_t) -1
	|| options.getegid () != (uid_t) -1)
	if (ACE_OS::setregid (options.getrgid (),
	options.getegid ()) == -1)
	{
	#if !defined (ACE_HAS_THREADS)
	// We can't emit this log message because ACELIB_ERROR(), etc.
	// will invoke async signal unsafe functions, which results
	// in undefined behavior in threaded programs.
	ACELIB_ERROR ((LM_ERROR,
	ACE_TEXT ("%p.\n"),
	ACE_TEXT ("ACE_Process::spawn: setregid failed.")));
	#endif
	}
	# endif /* ACE_LACKS_SETREGID */
	# if !defined (ACE_LACKS_SETREUID)
	// Set user and group id's.
	if (options.getruid () != (uid_t) -1
	|| options.geteuid () != (uid_t) -1)
	if (ACE_OS::setreuid (options.getruid (),
	options.geteuid ()) == -1)
	{
	#if !defined (ACE_HAS_THREADS)
	// We can't emit this log message because ACELIB_ERROR(), etc.
	// will invoke async signal unsafe functions, which results
	// in undefined behavior in threaded programs.
	ACELIB_ERROR ((LM_ERROR,
	ACE_TEXT ("%p.\n"),
	ACE_TEXT ("ACE_Process::spawn: setreuid failed.")));
	#endif
	}
	# endif /* ACE_LACKS_SETREUID */
	this->child (ACE_OS::getppid ());
	}

I suggest that separate the above set*id into a virtual member function named int set_child_uid_gid(ACE_Process_Options&) so that the user can overload it such as

int ...::set_child_uid_gid(ACE_Process_Optioins& opts)
{
    setrlimit ...
    return ACE_Process_Options::set_child_uid_gid(opts);
}