cygserver.cc

cygwin, 著名的在win32下模拟unix操作系统的东东

  version.major = CYGWIN_SERVER_VERSION_MAJOR;
  version.api   = CYGWIN_SERVER_VERSION_API;
  version.minor = CYGWIN_SERVER_VERSION_MINOR;
  version.patch = CYGWIN_SERVER_VERSION_PATCH;
}

class server_request : public queue_request
{
public:
  server_request (transport_layer_base *const conn, process_cache *const cache)
    : _conn (conn), _cache (cache)
  {}

  virtual ~server_request ()
  {
    safe_delete (_conn);
  }

  virtual void process ()
  {
    client_request::handle_request (_conn, _cache);
  }

private:
  transport_layer_base *const _conn;
  process_cache *const _cache;
};

class server_submission_loop : public queue_submission_loop
{
public:
  server_submission_loop (threaded_queue *const queue,
			  transport_layer_base *const transport,
			  process_cache *const cache)
    : queue_submission_loop (queue, false),
      _transport (transport),
      _cache (cache)
  {
    assert (_transport);
    assert (_cache);
  }

private:
  transport_layer_base *const _transport;
  process_cache *const _cache;

  virtual void request_loop ();
};

/* FIXME: this is a little ugly.  What we really want is to wait on
 * two objects: one for the pipe/socket, and one for being told to
 * shutdown.  Otherwise this will stay a problem (we won't actually
 * shutdown until the request _AFTER_ the shutdown request.  And
 * sending ourselves a request is ugly
 */
void
server_submission_loop::request_loop ()
{
  /* I'd like the accepting thread's priority to be above any "normal"
   * thread in the system to avoid overflowing the listen queue (for
   * sockets; similar issues exist for named pipes); but, for example,
   * a normal priority thread in a foregrounded process is boosted to
   * THREAD_PRIORITY_HIGHEST (AFAICT).  Thus try to set the current
   * thread's priority to a level one above that.  This fails on
   * win9x/ME so assume any failure in that call is due to that and
   * simply call again at one priority level lower.
   */
  if (!SetThreadPriority (GetCurrentThread (), THREAD_PRIORITY_HIGHEST + 1))
    if (!SetThreadPriority (GetCurrentThread (), THREAD_PRIORITY_HIGHEST))
      debug_printf ("failed to raise accept thread priority, error = %lu",
		    GetLastError ());

  while (_running)
    {
      bool recoverable = false;
      transport_layer_base *const conn = _transport->accept (&recoverable);
      if (!conn && !recoverable)
	{
	  system_printf ("fatal error on IPC transport: closing down");
	  return;
	}
      // EINTR probably implies a shutdown request; so back off for a
      // moment to let the main thread take control, otherwise the
      // server spins here receiving EINTR repeatedly since the signal
      // handler in the main thread doesn't get a chance to be called.
      if (!conn && errno == EINTR)
	{
	  if (!SetThreadPriority (GetCurrentThread (), THREAD_PRIORITY_NORMAL))
	    debug_printf ("failed to reset thread priority, error = %lu",
			  GetLastError ());

	  Sleep (0);
	  if (!SetThreadPriority (GetCurrentThread (),
				  THREAD_PRIORITY_HIGHEST + 1))
	    if (!SetThreadPriority (GetCurrentThread (),
				    THREAD_PRIORITY_HIGHEST))
	      debug_printf ("failed to raise thread priority, error = %lu",
			    GetLastError ());
	}
      if (conn)
	_queue->add (safe_new (server_request, conn, _cache));
    }
}

client_request_shutdown::client_request_shutdown ()
  : client_request (CYGSERVER_REQUEST_SHUTDOWN)
{
  // verbose: syscall_printf ("created");
}

void
client_request_shutdown::serve (transport_layer_base *, process_cache *)
{
  assert (!error_code ());

  if (msglen ())
    syscall_printf ("unexpected request body ignored: %lu bytes", msglen ());

  /* FIXME: link upwards, and then this becomes a trivial method call to
   * only shutdown _this queue_
   */

  kill (getpid (), SIGINT);

  msglen (0);
}

static sig_atomic_t shutdown_server = false;

static void
handle_signal (const int signum)
{
  /* any signal makes us die :} */

  shutdown_server = true;
}

/*
 * print_usage ()
 */

static void
print_usage (const char *const pgm)
{
  printf ("Usage: %s [OPTIONS]\n", pgm);
  printf ("  -c, --cleanup-threads   number of cleanup threads to use\n");
  printf ("  -h, --help              output usage information and exit\n");
  printf ("  -r, --request-threads   number of request threads to use\n");
  printf ("  -s, --shutdown          shutdown the daemon\n");
  printf ("  -v, --version           output version information and exit\n");
}

/*
 * print_version ()
 */

static void
print_version (const char *const pgm)
{
  char *vn = NULL;

  const char *const colon = strchr (version, ':');

  if (!colon)
    {
      vn = strdup ("?");
    }
  else
    {
      vn = strdup (colon + 2);	// Skip ": "

      char *const spc = strchr (vn, ' ');

      if (spc)
	*spc = '\0';
    }

  char buf[200];
  snprintf (buf, sizeof (buf), "%d.%d.%d(%d.%d/%d/%d)-(%d.%d.%d.%d) %s",
	    cygwin_version.dll_major / 1000,
	    cygwin_version.dll_major % 1000,
	    cygwin_version.dll_minor,
	    cygwin_version.api_major,
	    cygwin_version.api_minor,
	    cygwin_version.shared_data,
	    CYGWIN_SERVER_VERSION_MAJOR,
	    CYGWIN_SERVER_VERSION_API,
	    CYGWIN_SERVER_VERSION_MINOR,
	    CYGWIN_SERVER_VERSION_PATCH,
	    cygwin_version.mount_registry,
	    cygwin_version.dll_build_date);

  printf ("%s (cygwin) %s\n", pgm, vn);
  printf ("API version %s\n", buf);
  printf ("Copyright 2001, 2002 Red Hat, Inc.\n");
  printf ("Compiled on %s\n", __DATE__);

  free (vn);
}

/*
 * main ()
 */

int
main (const int argc, char *argv[])
{
  const struct option longopts[] = {
    {"cleanup-threads", required_argument, NULL, 'c'},
    {"help", no_argument, NULL, 'h'},
    {"request-threads", required_argument, NULL, 'r'},
    {"shutdown", no_argument, NULL, 's'},
    {"version", no_argument, NULL, 'v'},
    {0, no_argument, NULL, 0}
  };

  const char opts[] = "c:hr:sv";

  int cleanup_threads = 2;
  int request_threads = 10;
  bool shutdown = false;

  const char *pgm = NULL;

  if (!(pgm = strrchr (*argv, '\\')) && !(pgm = strrchr (*argv, '/')))
    pgm = *argv;
  else
    pgm++;

  wincap.init ();
  if (wincap.has_security ())
    setup_privileges ();

  int opt;

  while ((opt = getopt_long (argc, argv, opts, longopts, NULL)) != EOF)
    switch (opt)
      {
      case 'c':
	cleanup_threads = atoi (optarg);
	if (cleanup_threads <= 0)
	  {
	    fprintf (stderr,
		     "%s: number of cleanup threads must be positive\n",
		     pgm);
	    exit (1);
	  }
	break;

      case 'h':
	print_usage (pgm);
	return 0;

      case 'r':
	request_threads = atoi (optarg);
	if (request_threads <= 0)
	  {
	    fprintf (stderr,
		     "%s: number of request threads must be positive\n",
		     pgm);
	    exit (1);
	  }
	break;

      case 's':
	shutdown = true;
	break;

      case 'v':
	print_version (pgm);
	return 0;

      case '?':
	fprintf (stderr, "Try `%s --help' for more information.\n", pgm);
	exit (1);
      }

  if (optind != argc)
    {
      fprintf (stderr, "%s: too many arguments\n", pgm);
      exit (1);
    }

  if (shutdown)
    {
      /* Setting `cygserver_running' stops the request code making a
       * version request, which is not much to the point.
       */
      cygserver_running = CYGSERVER_OK;

      client_request_shutdown req;

      if (req.make_request () == -1 || req.error_code ())
	{
	  fprintf (stderr, "%s: shutdown request failed: %s\n",
		   pgm, strerror (req.error_code ()));
	  exit (1);
	}

      // FIXME: It would be nice to wait here for the daemon to exit.

      return 0;
    }

#define SIGHANDLE(SIG)							\
  do									\
    {									\
      struct sigaction act;						\
									\
      act.sa_handler = &handle_signal;					\
      act.sa_mask = 0;							\
      act.sa_flags = 0;							\
									\
      if (sigaction (SIG, &act, NULL) == -1)				\
	{								\
	  system_printf ("failed to install handler for " #SIG ": %s",	\
			 strerror (errno));				\
	  exit (1);							\
	}								\
    } while (false)

  SIGHANDLE (SIGHUP);
  SIGHANDLE (SIGINT);
  SIGHANDLE (SIGTERM);

  print_version (pgm);
  setbuf (stdout, NULL);
  printf ("daemon starting up");

  threaded_queue request_queue (request_threads);
  printf (".");

  transport_layer_base *const transport = create_server_transport ();
  assert (transport);
  printf (".");

  process_cache cache (cleanup_threads);
  printf (".");

  server_submission_loop submission_loop (&request_queue, transport, &cache);
  printf (".");

  request_queue.add_submission_loop (&submission_loop);
  printf (".");

  if (transport->listen () == -1)
    {
      exit (1);
    }
  printf (".");

  cache.start ();
  printf (".");

  request_queue.start ();
  printf (".");

  printf ("complete\n");

  /* TODO: wait on multiple objects - the thread handle for each
   * request loop + all the process handles. This should be done by
   * querying the request_queue and the process cache for all their
   * handles, and then waiting for (say) 30 seconds.  after that we
   * recreate the list of handles to wait on, and wait again.  the
   * point of all this abstraction is that we can trivially server
   * both sockets and pipes simply by making a new transport, and then
   * calling request_queue.process_requests (transport2);
   */
  /* WaitForMultipleObjects abort && request_queue && process_queue && signal
     -- if signal event then retrigger it
  */
  while (!shutdown_server && request_queue.running () && cache.running ())
    pause ();

  printf ("\nShutdown request received - new requests will be denied\n");
  request_queue.stop ();
  printf ("All pending requests processed\n");
  safe_delete (transport);
  printf ("No longer accepting requests - cygwin will operate in daemonless mode\n");
  cache.stop ();
  printf ("All outstanding process-cache activities completed\n");
  printf ("daemon shutdown\n");

  return 0;
}