jack1/jackd/jackd.c

/*
    Copyright (C) 2001 Paul Davis
    
    This program is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    This program is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with this program; if not, write to the Free Software
    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

    $Id$
*/

#include <stdio.h>
#include <signal.h>
#include <getopt.h>
#include <sys/types.h>
#include <sys/shm.h>
#include <string.h>
#include <errno.h>
#include <wait.h>

#include <config.h>

#include <jack/engine.h>
#include <jack/internal.h>
#include <jack/driver.h>

#ifdef USE_CAPABILITIES

#include <sys/stat.h>
/* capgetp and capsetp are linux only extensions, not posix */
#undef _POSIX_SOURCE
#include <sys/capability.h>
#include <jack/start.h>

static struct stat pipe_stat;

#endif

static sigset_t signals;
static jack_engine_t *engine = 0;
static int jackd_pid;
static int realtime = 0;
static int realtime_priority = 10;
static int with_fork = 1;
static int verbose = 0;
static int asio_mode = 0;

typedef struct {
    pid_t  pid;
    int argc;
    char **argv;
} waiter_arg_t;

static void
signal_handler (int sig)
{
	/* this is used by the parent (waiter) process */

	fprintf (stderr, "jackd: signal %d received\n", sig);
	kill (jackd_pid, SIGTERM);
}

static void 
do_nothing_handler (int sig)
{
	/* this is used by the child (active) process, but it never 
	   gets called unless we are already shutting down
	   after another signal.
	*/

	char buf[32];
	snprintf (buf, sizeof(buf), "received signal %d during shutdown (ignored)\n", sig);
	write (1, buf, strlen (buf));
}

static void *
jack_engine_waiter_thread (void *arg)
{
	waiter_arg_t *warg = (waiter_arg_t *) arg;

	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, NULL);

	if ((engine = jack_engine_new (realtime, realtime_priority, verbose)) == 0) {
		fprintf (stderr, "cannot create engine\n");
		kill (warg->pid, SIGTERM);
		return 0;
	}

	if (warg->argc) {

		fprintf (stderr, "loading driver ..\n");
		
		if (jack_engine_load_driver (engine, warg->argc, warg->argv)) {
			fprintf (stderr, "cannot load driver module %s\n", warg->argv[0]);
			kill (warg->pid, SIGTERM);
			return 0;
		}

	} else {

		fprintf (stderr, "No driver specified ... hmm. JACK won't do anything when run like this.\n");
	}

	if (asio_mode) {
		jack_set_asio_mode (engine, TRUE);
	} 

	fprintf (stderr, "starting engine\n");

	if (jack_run (engine)) {
		fprintf (stderr, "cannot start main JACK thread\n");
		kill (warg->pid, SIGTERM);
		return 0;
	}

	jack_wait (engine);

	fprintf (stderr, "telling signal thread that the engine is done\n");
	kill (warg->pid, SIGHUP);

	return 0; /* nobody cares what this returns */
}

static void
jack_main (int argc, char **argv)
{
	int sig;
	int i;
	pthread_t waiter_thread;
	waiter_arg_t warg;
	sigset_t allsignals;
	struct sigaction action;

	/* remove any existing files from a previous instance */
	
	jack_cleanup_files ();

	pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, NULL);

	/* what's this for?

	   POSIX says that signals are delivered like this:

	   * if a thread has blocked that signal, it is not
	       a candidate to receive the signal.
           * of all threads not blocking the signal, pick
	       one at random, and deliver the signal.

           this means that a simple-minded multi-threaded
	   program can expect to get POSIX signals delivered
	   randomly to any one of its threads, 

	   here, we block all signals that we think we
	   might receive and want to catch. all "child"
	   threads will inherit this setting. if we
	   create a thread that calls sigwait() on the
	   same set of signals, implicitly unblocking
	   all those signals. any of those signals that
	   are delivered to the process will be delivered
	   to that thread, and that thread alone. this
	   makes cleanup for a signal-driven exit much
	   easier, since we know which thread is doing
	   it and more importantly, we are free to
	   call async-unsafe functions, because the
	   code is executing in normal thread context
	   after a return from sigwait().
	*/

	sigemptyset (&signals);
	sigaddset(&signals, SIGHUP);
	sigaddset(&signals, SIGINT);
	sigaddset(&signals, SIGQUIT);
	sigaddset(&signals, SIGILL);
	sigaddset(&signals, SIGTRAP);
	sigaddset(&signals, SIGABRT);
	sigaddset(&signals, SIGIOT);
	sigaddset(&signals, SIGFPE);
	sigaddset(&signals, SIGPIPE);
	sigaddset(&signals, SIGTERM);
	sigaddset(&signals, SIGUSR1);
	sigaddset(&signals, SIGSEGV);

	/* all child threads will inherit this mask unless they explicitly reset it */

	pthread_sigmask (SIG_BLOCK, &signals, 0);
	
	/* what we'd really like to do here is to be able to 
	   wait for either the engine to stop or a POSIX signal,
	   whichever arrives sooner. but there is no mechanism
	   to do that, so instead we create a thread to wait
	   for the engine to finish, and here we stop and wait
	   for any (reasonably likely) POSIX signal.

	   if the engine finishes first, the waiter thread will
	   tell us about it via a signal.

	   if a signal arrives, we'll stop the engine and then
	   exit. 

	   in normal operation, our parent process will be waiting
	   for us and will cleanup.
	*/

	warg.pid = getpid();
	warg.argc = argc;
	warg.argv = argv;

	if (pthread_create (&waiter_thread, 0, jack_engine_waiter_thread, &warg)) {
		fprintf (stderr, "jackd: cannot create engine waiting thread\n");
		return;
	}

	/* install a do-nothing handler because otherwise
	   pthreads behaviour is undefined when we enter
	   sigwait.
	*/
	
	sigfillset (&allsignals);

	action.sa_handler = do_nothing_handler;
	action.sa_mask = allsignals;
	action.sa_flags = SA_RESTART|SA_RESETHAND;

	for (i = 0; i < NSIG; i++) {
		if (sigismember (&signals, i)) {
			sigaction (i, &action, 0);
		} 
	}
	
	if (verbose) {
		fprintf (stderr, "%d waiting for signals\n", getpid());
	}

	while(1) {
		sigwait (&signals, &sig);

		fprintf (stderr, "jack main caught signal %d\n", sig);
		
		if (sig == SIGUSR1) {
			jack_dump_configuration(engine, 1);
		} else {
			/* continue to kill engine */
			break;
		}
	} 

	if (sig != SIGSEGV) {

		/* unblock signals so we can see them during shutdown.
		   this will help prod developers not to lose sight
		   of bugs that cause segfaults etc. during shutdown.
		*/

		sigprocmask (SIG_UNBLOCK, &signals, 0);
	}

	pthread_cancel (waiter_thread);
	jack_engine_delete (engine);

	return;
}

static void usage (FILE *file) 

{
	fprintf (file, "\n"
		 "usage: jackd [ --asio OR -a ]\n"
		 "             [ --realtime OR -R [ --realtime-priority OR -P priority ] ]\n"
		 "             [ --verbose OR -v ]\n"
		 "             [ --tmpdir OR -D directory-for-temporary-files ]\n"
		 "             [ --version OR -V ]\n"
		 "         -d driver [ ... driver args ... ]\n");
}	

int	       
main (int argc, char *argv[])

{
	const char *options = "-ad:D:P:vhVRFl:";
	struct option long_options[] = 
	{ 
		{ "asio", 0, 0, 'a' },
		{ "driver", 1, 0, 'd' },
		{ "tmpdir", 1, 0, 'D' },
		{ "verbose", 0, 0, 'v' },
		{ "help", 0, 0, 'h' },
		{ "realtime", 0, 0, 'R' },
		{ "realtime-priority", 1, 0, 'P' },
		{ "spoon", 0, 0, 'F' },
		{ "version", 0, 0, 'V' },
		{ 0, 0, 0, 0 }
	};
	int option_index;
	int opt;
	int seen_driver = 0;
	char *driver_name = 0;
	char **driver_args = 0;
	int driver_nargs = 1;
	int show_version = 0;
	int i;
#ifdef USE_CAPABILITIES
	int status;
#endif

#ifdef USE_CAPABILITIES

	/* check to see if there is a pipe in the right descriptor */
	if ((status = fstat (PIPE_WRITE_FD, &pipe_stat)) == 0 && S_ISFIFO(pipe_stat.st_mode)) {
		/* tell jackstart we are up and running */
		if (close(PIPE_WRITE_FD) != 0) {
			fprintf(stderr, "jackd: error on startup pipe close: %s\n", strerror (errno));
		} else {
			/* wait for jackstart process to set our capabilities */
			if (wait (&status) == -1) {
				fprintf (stderr, "jackd: wait for startup process exit failed\n");
			}
			if (!WIFEXITED (status) || WEXITSTATUS (status)) {
				fprintf(stderr, "jackd: jackstart did not exit cleanly\n");
				exit (1);
			}
		}
	}
#endif

	opterr = 0;
	while (!seen_driver && (opt = getopt_long (argc, argv, options, long_options, &option_index)) != EOF) {
		switch (opt) {
		case 'a':
			asio_mode = TRUE;
			break;

		case 'D':
			jack_set_server_dir (optarg);
			break;

		case 'd':
			seen_driver = 1;
			driver_name = optarg;
			break;

		case 'v':
			verbose = 1;
			break;

		case 'F':
			with_fork = 0;
			break;

		case 'P':
			realtime_priority = atoi (optarg);
			break;

		case 'R':
			realtime = 1;
			break;

		case 'V':
			show_version = 1;
			break;

		default:
			fprintf (stderr, "unknown option character %c\n", optopt);
			/*fallthru*/
		case 'h':
			usage (stdout);
			return -1;
		}
	}

	if (show_version) {
		printf ( "jackd version " VERSION "\n");
		return -1;
	}

	if (!seen_driver) {
		usage (stderr);
		exit (1);
	}

	if (optind < argc) {
		driver_nargs = 1 + argc - optind;
	} else {
		driver_nargs = 1;
	}

	driver_args = (char **) malloc (sizeof (char *) * driver_nargs);
	driver_args[0] = driver_name;
	
	for (i = 1; i < driver_nargs; i++) {
		driver_args[i] = argv[optind++];
	}

	printf ( "jackd " VERSION "\n"
		 "Copyright 2001-2002 Paul Davis and others.\n"
		 "jackd comes with ABSOLUTELY NO WARRANTY\n"
		 "This is free software, and you are welcome to redistribute it\n"
		 "under certain conditions; see the file COPYING for details\n\n");

	if (!with_fork) {

		/* This is really here so that we can run gdb easily */

		jack_main (driver_nargs, driver_args);

	} else {

		int pid = fork ();
		
		if (pid < 0) {

			fprintf (stderr, "could not fork jack server (%s)", strerror (errno));
			exit (1);

		} else if (pid == 0) {

			jack_main (driver_nargs, driver_args);

		} else {
			jackd_pid = pid;

			signal (SIGHUP, signal_handler);
			signal (SIGINT, signal_handler);
			signal (SIGQUIT, signal_handler);
			signal (SIGTERM, signal_handler);

			waitpid (pid, NULL, 0);
		}
	}

	jack_cleanup_shm ();
	jack_cleanup_files ();

	return 0;
}