~upstart-devel/upstart/trunk

/* upstart
 *
 * Copyright  2009-2011 Canonical Ltd.
 * Author: Scott James Remnant <scott@netsplit.com>.
 *
 * This program is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License version 2, as
 * published by the Free Software Foundation.
 *
 * 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.,
 * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
 */

#ifdef HAVE_CONFIG_H
# include <config.h>
#endif /* HAVE_CONFIG_H */


#include <sys/types.h>
#include <sys/time.h>
#include <sys/wait.h>
#include <sys/ioctl.h>
#include <sys/reboot.h>
#include <sys/resource.h>
#include <sys/mount.h>

#ifdef HAVE_SYS_PRCTL_H
#include <sys/prctl.h>
#ifndef PR_SET_CHILD_SUBREAPER
#define PR_SET_CHILD_SUBREAPER 35
#endif
#endif

#include <errno.h>
#include <stdio.h>
#include <limits.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>
#include <syslog.h>
#include <unistd.h>

#include <linux/kd.h>

#include <nih/macros.h>
#include <nih/alloc.h>
#include <nih/list.h>
#include <nih/timer.h>
#include <nih/signal.h>
#include <nih/child.h>
#include <nih/option.h>
#include <nih/main.h>
#include <nih/error.h>
#include <nih/logging.h>

#include "paths.h"
#include "events.h"
#include "system.h"
#include "job_class.h"
#include "job_process.h"
#include "event.h"
#include "conf.h"
#include "control.h"
#include "state.h"
#include "xdg.h"


/* Prototypes for static functions */
#ifndef DEBUG
static int  logger_kmsg     (NihLogLevel priority, const char *message);
static void crash_handler   (int signum);
#endif /* DEBUG */
static void term_handler    (void *data, NihSignal *signal);
#ifndef DEBUG
static void cad_handler     (void *data, NihSignal *signal);
static void kbd_handler     (void *data, NihSignal *signal);
static void pwr_handler     (void *data, NihSignal *signal);
static void hup_handler     (void *data, NihSignal *signal);
static void usr1_handler    (void *data, NihSignal *signal);
#endif /* DEBUG */

static void handle_confdir          (void);
static void handle_logdir           (void);
static int  console_type_setter     (NihOption *option, const char *arg);
static int  conf_dir_setter         (NihOption *option, const char *arg);
static int  prepend_conf_dir_setter (NihOption *option, const char *arg);
static int  append_conf_dir_setter  (NihOption *option, const char *arg);


/**
 * state_fd:
 *
 * File descriptor to read serialised state from when performing
 * stateful re-exec. If value is not -1, attempt stateful re-exec.
 **/
static int state_fd = -1;

/**
 * conf_dirs:
 *
 * Array of full paths to job configuration file directories.
 **/
static char **conf_dirs = NULL;

/**
 * prepend_conf_dirs:
 *
 * Array of full paths to job configuration file directories that will
 * be added to before the other values in conf_dirs.
 **/
static char **prepend_conf_dirs = NULL;

/**
 * append_conf_dirs:
 *
 * Array of full paths to job configuration file directories that will
 * be added to conf_dirs.
 **/
static char **append_conf_dirs = NULL;

/**
 * initial_event:
 *
 * Alternate event to emit at startup (rather than STARTUP_EVENT).
 **/
static char *initial_event = NULL;

/**
 * disable_startup_event:
 *
 * If TRUE, do not emit a startup event.
 **/
static int disable_startup_event = FALSE;

/**
 * disable_dbus:
 *
 * If TRUE, do not connect to a D-Bus bus
 * (only connect to the private socket).
 **/
static int disable_dbus = FALSE;

extern int          no_inherit_env;
extern int          user_mode;
extern int          chroot_sessions;
extern int          disable_job_logging;
extern int          use_session_bus;
extern int          default_console;
extern int          write_state_file;
extern char        *log_dir;
extern DBusBusType  dbus_bus_type;
extern mode_t       initial_umask;
extern int          debug_stanza_enabled;

#ifdef ENABLE_CGROUPS
extern int          disable_cgroups;
#endif /* ENABLE_CGROUPS */

/**
 * options:
 *
 * Command-line options we accept.
 **/
static NihOption options[] = {
	{ 0, "append-confdir", N_("specify additional directory to load configuration files from"),
		NULL, "DIR", NULL, append_conf_dir_setter },

	{ 0, "chroot-sessions", N_("enable chroot sessions"),
		NULL, NULL, &chroot_sessions, NULL },

	{ 0, "confdir", N_("specify alternative directory to load configuration files from"),
		NULL, "DIR", NULL, conf_dir_setter },

	{ 0, "default-console", N_("default value for console stanza"),
		NULL, "VALUE", NULL, console_type_setter },

	{ 0, "logdir", N_("specify alternative directory to store job output logs in"),
		NULL, "DIR", &log_dir, NULL },

#ifdef ENABLE_CGROUPS
	{ 0, "no-cgroups", N_("do not support cgroups"),
		NULL, NULL, &disable_cgroups, NULL },
#endif /* ENABLE_CGROUPS */

	{ 0, "no-dbus", N_("do not connect to a D-Bus bus"),
		NULL, NULL, &disable_dbus, NULL },

	{ 0, "no-inherit-env", N_("jobs will not inherit environment of init"),
		NULL, NULL, &no_inherit_env , NULL },

	{ 0, "no-log", N_("disable job logging"),
		NULL, NULL, &disable_job_logging, NULL },

	{ 0, "no-startup-event", N_("do not emit any startup event (for testing)"),
		NULL, NULL, &disable_startup_event, NULL },

	{ 0, "prepend-confdir", N_("specify additional initial directory to load configuration files from"),
		NULL, "DIR", NULL, prepend_conf_dir_setter },

	/* Must be specified for both stateful and stateless re-exec */
	{ 0, "restart", N_("flag a re-exec has occurred"),
		NULL, NULL, &restart, NULL },

	/* Required for stateful re-exec */
	{ 0, "state-fd", N_("specify file descriptor to read serialisation data from"),
		NULL, "FD", &state_fd, nih_option_int },

	{ 0, "session", N_("use D-Bus session bus rather than system bus (for testing)"),
		NULL, NULL, &use_session_bus, NULL },

	{ 0, "startup-event", N_("specify an alternative initial event (for testing)"),
		NULL, "NAME", &initial_event, NULL },

	{ 0, "user", N_("start in user mode (as used for user sessions)"),
		NULL, NULL, &user_mode, NULL },

	{ 0, "write-state-file", N_("attempt to write state file on every re-exec"),
		NULL, NULL, &write_state_file, NULL },

	/* Ignore invalid options */
	{ '-', "--", NULL, NULL, NULL, NULL, NULL },

	NIH_OPTION_LAST
};


int
main (int   argc,
      char *argv[])
{
	char **args = NULL;
	int    ret;

	conf_dirs = NIH_MUST (nih_str_array_new (NULL));
	append_conf_dirs = NIH_MUST (nih_str_array_new (NULL));
	prepend_conf_dirs = NIH_MUST (nih_str_array_new (NULL));

	args_copy = NIH_MUST (nih_str_array_copy (NULL, NULL, argv));

	nih_main_init (args_copy[0]);

	nih_option_set_synopsis (_("Process management daemon."));
	nih_option_set_help (
		_("This daemon is normally executed by the kernel and given "
		  "process id 1 to denote its special status.  When executed "
		  "by a user process, it will actually run /sbin/telinit."));

	args = nih_option_parser (NULL, argc, argv, options, FALSE);
	if (! args)
		exit (1);

	if (nih_log_priority == NIH_LOG_DEBUG)
		debug_stanza_enabled = TRUE;

	handle_confdir ();
	handle_logdir ();

	if (disable_job_logging)
		nih_debug ("Job logging disabled");

	if (getenv (USE_SESSION_BUS_ENV))
		use_session_bus = TRUE;

	if (! user_mode)
		no_inherit_env = TRUE;

#ifndef DEBUG
	if (use_session_bus == FALSE && user_mode == FALSE) {

		int needs_devtmpfs = 0;

		/* Check we're root */
		if (getuid ()) {
			nih_fatal (_("Need to be root"));
			exit (1);
		}

		/* Check we're process #1 */
		if (getpid () > 1) {
			execv (TELINIT, argv);
			/* Ignore failure, probably just that telinit doesn't exist */

			nih_fatal (_("Not being executed as init"));
			exit (1);
		}

		/* Clear our arguments from the command-line, so that we show up in
		 * ps or top output as /sbin/init, with no extra flags.
		 *
		 * This is a very Linux-specific trick; by deleting the NULL
		 * terminator at the end of the last argument, we fool the kernel
		 * into believing we used a setproctitle()-a-like to extend the
		 * argument space into the environment space, and thus make it use
		 * strlen() instead of its own assumed length.  In fact, we've done
		 * the exact opposite, and shrunk the command line length to just that
		 * of whatever is in argv[0].
		 *
		 * If we don't do this, and just write \0 over the rest of argv, for
		 * example; the command-line length still includes those \0s, and ps
		 * will show whitespace in their place.
		 */
		if (argc > 1) {
			char *arg_end;

			arg_end = argv[argc-1] + strlen (argv[argc-1]);
			*arg_end = ' ';
		}


		/* Become the leader of a new session and process group, shedding
		 * any controlling tty (which we shouldn't have had anyway - but
		 * you never know what initramfs did).
		 */
		setsid ();

		/* Allow devices to be created with the actual perms
		 * specified.
		 */
		initial_umask = umask (0);

		/* Check if key /dev entries already exist; if they do,
		 * we should assume we don't need to mount /dev.
		 */
		if (system_check_file ("/dev/ptmx", S_IFCHR, makedev (5, 2)) < 0
			|| system_check_file ("/dev/pts", S_IFDIR, 0) < 0)
			needs_devtmpfs = 1;

		if (needs_devtmpfs) {
			if (system_mount ("devtmpfs", "/dev",
					  MS_NOEXEC | MS_NOSUID, NULL) < 0) {
				NihError *err;

				err = nih_error_get ();
				nih_error ("%s: %s", _("Unable to mount /dev filesystem"),
						err->message);
				nih_free (err);
			}

			/* Required to exist before /dev/pts accessed */
			system_mknod ("/dev/ptmx", (S_IFCHR | 0666), makedev (5, 2));

			if (mkdir ("/dev/pts", 0755) < 0 && errno != EEXIST)
				nih_error ("%s: %s", _("Cannot create directory"), "/dev/pts");
		}

		if (system_mount ("devpts", "/dev/pts", MS_NOEXEC | MS_NOSUID,
				  "gid=5,mode=0620") < 0) {
			NihError *err;

			err = nih_error_get ();
			nih_error ("%s: %s", _("Unable to mount /dev/pts filesystem"),
					err->message);
			nih_free (err);
		}

		/* These devices must exist, but we have to have handled the /dev
		 * check (and possible mount) prior to considering
		 * creating them. And yet, if /dev is not available from
		 * the outset and an error occurs, we are unable to report it,
		 * hence these checks are performed as early as is
		 * feasible.
		 */
		system_mknod ("/dev/null", (S_IFCHR | 0666), makedev (1, 3));
		system_mknod ("/dev/tty", (S_IFCHR | 0666), makedev (5, 0));
		system_mknod ("/dev/console", (S_IFCHR | 0600), makedev (5, 1));
		system_mknod ("/dev/kmsg", (S_IFCHR | 0600), makedev (1, 11));

		/* Set the standard file descriptors to the ordinary console device,
		 * resetting it to sane defaults unless we're inheriting from another
		 * init process which we know left it in a sane state.
		 */
		if (system_setup_console (CONSOLE_OUTPUT, (! restart)) < 0) {
			NihError *err;

			err = nih_error_get ();

			nih_warn ("%s: %s", _("Unable to initialize console, will try /dev/null"),
				  err->message);
			nih_free (err);
	
			if (system_setup_console (CONSOLE_NONE, FALSE) < 0) {
				err = nih_error_get ();
				nih_fatal ("%s: %s", _("Unable to initialize console as /dev/null"),
					   err->message);
				nih_free (err);
	
				exit (1);
			}
		}

		/* Set the PATH environment variable */
		setenv ("PATH", PATH, TRUE);

		/* Switch to the root directory in case we were started from some
		 * strange place, or worse, some directory in the initramfs that's
		 * going to go away soon.
		 */
		if (chdir ("/"))
			nih_warn ("%s: %s", _("Unable to set root directory"),
				strerror (errno));

		/* Mount the /proc and /sys filesystems, which are pretty much
		 * essential for any Linux system; not to mention used by
		 * ourselves. Also mount /dev/pts to allow CONSOLE_LOG
		 * to function if booted in an initramfs-less environment.
		 */
		if (system_mount ("proc", "/proc",
				  MS_NODEV | MS_NOEXEC | MS_NOSUID, NULL) < 0) {
			NihError *err;

			err = nih_error_get ();
			nih_warn ("%s: %s", _("Unable to mount /proc filesystem"),
				err->message);
			nih_free (err);
		}

		if (system_mount ("sysfs", "/sys",
				  MS_NODEV | MS_NOEXEC | MS_NOSUID, NULL) < 0) {
			NihError *err;

			err = nih_error_get ();
			nih_warn ("%s: %s", _("Unable to mount /sys filesystem"),
				err->message);
			nih_free (err);
		}

	} else {
		nih_debug ("Running with UID %d as PID %d (PPID %d)",
				(int)getuid (), (int)getpid (), (int)getppid ());
	}

#else /* DEBUG */
	nih_log_set_priority (NIH_LOG_DEBUG);
	nih_debug ("Running with UID %d as PID %d (PPID %d)",
		(int)getuid (), (int)getpid (), (int)getppid ());
#endif /* DEBUG */

	if (user_mode) {
		/* Save initial value */
		initial_umask = umask (0);
		(void)umask (initial_umask);
	}

	/* Reset the signal state and install the signal handler for those
	 * signals we actually want to catch; this also sets those that
	 * can be sent to us, because we're special
	 */
	if (! restart)
		nih_signal_reset ();

#ifndef DEBUG
	if (use_session_bus == FALSE && user_mode == FALSE) {
		/* Catch fatal errors immediately rather than waiting for a new
		 * iteration through the main loop.
		 */
		nih_signal_set_handler (SIGSEGV, crash_handler);
		nih_signal_set_handler (SIGABRT, crash_handler);
	}
#endif /* DEBUG */

	/* Don't ignore SIGCHLD or SIGALRM, but don't respond to them
	 * directly; it's enough that they interrupt the main loop and
	 * get dealt with during it.
	 */
	nih_signal_set_handler (SIGCHLD, nih_signal_handler);
	nih_signal_set_handler (SIGALRM, nih_signal_handler);

#ifndef DEBUG
	if (use_session_bus == FALSE && user_mode == FALSE) {
		/* Ask the kernel to send us SIGINT when control-alt-delete is
		 * pressed; generate an event with the same name.
		 */
		reboot (RB_DISABLE_CAD);
		nih_signal_set_handler (SIGINT, nih_signal_handler);
		NIH_MUST (nih_signal_add_handler (NULL, SIGINT, cad_handler, NULL));

		/* Ask the kernel to send us SIGWINCH when alt-uparrow is pressed;
		 * generate a keyboard-request event.
		 */
		if (ioctl (0, KDSIGACCEPT, SIGWINCH) == 0) {
			nih_signal_set_handler (SIGWINCH, nih_signal_handler);
			NIH_MUST (nih_signal_add_handler (NULL, SIGWINCH,
						kbd_handler, NULL));
		}

		/* powstatd sends us SIGPWR when it changes /etc/powerstatus */
		nih_signal_set_handler (SIGPWR, nih_signal_handler);
		NIH_MUST (nih_signal_add_handler (NULL, SIGPWR, pwr_handler, NULL));

	}

	/* SIGHUP instructs us to re-load our configuration */
	nih_signal_set_handler (SIGHUP, nih_signal_handler);
	NIH_MUST (nih_signal_add_handler (NULL, SIGHUP, hup_handler, NULL));

	/* Session Inits only reconnect to D-Bus when notified
	 * via their private socket.
	 */
	if (! user_mode) {
		/* SIGUSR1 instructs us to reconnect to D-Bus */
		nih_signal_set_handler (SIGUSR1, nih_signal_handler);
		NIH_MUST (nih_signal_add_handler (NULL, SIGUSR1, usr1_handler, NULL));
	}

	/* SIGTERM instructs us to re-exec ourselves when running as PID
	 * 1, or to exit when running as a Session Init; this signal should
	 * be the last in the list to ensure that all other signals are
	 * handled before a SIGTERM.
	 */
	nih_signal_set_handler (SIGTERM, nih_signal_handler);
	NIH_MUST (nih_signal_add_handler (NULL, SIGTERM, term_handler, NULL));

#endif /* DEBUG */


	/* Watch children for events */
	NIH_MUST (nih_child_add_watch (NULL, -1, NIH_CHILD_ALL,
				       job_process_handler, NULL));

	/* Process the event queue each time through the main loop */
	NIH_MUST (nih_main_loop_add_func (NULL, (NihMainLoopCb)event_poll,
					  NULL));


	/* Adjust our OOM priority to the default, which will be inherited
	 * by all jobs.
	 */
	if (JOB_DEFAULT_OOM_SCORE_ADJ) {
		char  filename[PATH_MAX];
		int   oom_value;
		FILE *fd;

		snprintf (filename, sizeof (filename),
			  "/proc/%d/oom_score_adj", getpid ());
		oom_value = JOB_DEFAULT_OOM_SCORE_ADJ;
		fd = fopen (filename, "w");
		if ((! fd) && (errno == ENOENT)) {
			snprintf (filename, sizeof (filename),
				  "/proc/%d/oom_adj", getpid ());
			oom_value = (JOB_DEFAULT_OOM_SCORE_ADJ
				     * ((JOB_DEFAULT_OOM_SCORE_ADJ < 0) ? 17 : 15)) / 1000;
			fd = fopen (filename, "w");
		}
		if (! fd) {
			nih_warn ("%s: %s", _("Unable to set default oom score"),
				  strerror (errno));
		} else {
			fprintf (fd, "%d\n", oom_value);

			if (fclose (fd))
				nih_warn ("%s: %s", _("Unable to set default oom score"),
					  strerror (errno));
		}
	}


	if (restart) {
		if (state_fd == -1) {
			nih_warn ("%s",
				_("Stateful re-exec supported but stateless re-exec requested"));
		} else if (state_read (state_fd) < 0) {

			/* Stateful re-exec has failed so try once more by
			 * degrading to stateless re-exec, which even in
			 * the case of low-memory scenarios will work.
			 */

			/* Inform the child we've given up on stateful
			 * re-exec.
			 */
			close (state_fd);

			nih_error ("%s - %s",
				_("Failed to read serialisation data"),
				_("reverting to stateless re-exec"));

			/* Remove any existing (but now stale) state fd
			 * args which will effectively disable stateful
			 * re-exec.
			 */
			clean_args (&args_copy);

			/* Attempt stateless re-exec */
			perform_reexec ();

			nih_error ("%s",
				_("Both stateful and stateless re-execs failed"));

			/* Out of options */
			nih_assert_not_reached ();
		} else {
			close (state_fd);

			nih_info ("Stateful re-exec completed");
		}
	}

	/* Only honour command-line options affecting configuration
	 * directories if not restarting, or if performing a stateless
	 * re-exec.
	 */
	if (! restart || (restart && state_fd == -1)) {
		/* Read configuration */
		if (prepend_conf_dirs[0]) {
			for (char **d = prepend_conf_dirs; d && *d; d++) {
				nih_debug ("Prepending configuration directory %s", *d);
				NIH_MUST (conf_source_new (NULL, *d, CONF_JOB_DIR));
			}
		}

		if (! user_mode) {
			nih_assert (conf_dirs[0]);

			NIH_MUST (conf_source_new (NULL, CONFFILE, CONF_FILE));

			for (char **d = conf_dirs; d && *d; d++) {
				nih_debug ("Using configuration directory %s", *d);
				NIH_MUST (conf_source_new (NULL, *d, CONF_JOB_DIR));
			}
		} else {
			nih_local char **dirs = NULL;

			dirs = NIH_MUST (get_user_upstart_dirs ());

			for (char **d = conf_dirs[0] ? conf_dirs : dirs; d && *d; d++) {
				nih_debug ("Using configuration directory %s", *d);
				NIH_MUST (conf_source_new (NULL, *d, CONF_JOB_DIR));
			}
		}

		if (append_conf_dirs[0]) {
			for (char **d = append_conf_dirs; d && *d; d++) {
				nih_debug ("Adding configuration directory %s", *d);
				NIH_MUST (conf_source_new (NULL, *d, CONF_JOB_DIR));
			}
		}
	}

	nih_free (conf_dirs);
	nih_free (prepend_conf_dirs);
	nih_free (append_conf_dirs);

	job_class_environment_init ();

	conf_reload ();

	/* We must have atleast one source of configuration */
	nih_assert (! NIH_LIST_EMPTY (conf_sources));

	/* Create a listening server for private connections. */
	if (use_session_bus == FALSE) {
		while (control_server_open () < 0) {
			NihError *err;

			err = nih_error_get ();
			if (err->number != ENOMEM) {
				nih_warn ("%s: %s", _("Unable to listen for private connections"),
					err->message);
				nih_free (err);
				break;
			}
			nih_free (err);
		}
	}

	/* Open connection to the appropriate D-Bus bus; we normally expect this to
	 * fail (since dbus-daemon probably isn't running yet) and will try again
	 * later - don't let ENOMEM stop us though.
	 */
	if (disable_dbus) {
		nih_info (_("Not connecting to %s bus"),
				use_session_bus ? "session" : "system");
	} else {
		while (control_bus_open () < 0) {
			NihError *err;
			int       number;

			err = nih_error_get ();
			number = err->number;
			nih_free (err);

			if (number != ENOMEM)
				break;
		}
	}

#ifndef DEBUG
	if (use_session_bus == FALSE && user_mode == FALSE) {
		/* Now that the startup is complete, send all further logging output
		 * to kmsg instead of to the console.
		 */
		if (system_setup_console (CONSOLE_NONE, FALSE) < 0) {
			NihError *err;
			
			err = nih_error_get ();
			nih_fatal ("%s: %s", _("Unable to setup standard file descriptors"),
				   err->message);
			nih_free (err);
	
			exit (1);
		}

		nih_log_set_logger (logger_kmsg);
	}
#endif /* DEBUG */


	/* Generate and run the startup event or read the state from the
	 * init daemon that exec'd us
	 */
	if (! restart) {
		if (disable_startup_event) {
			nih_debug ("Startup event disabled");
		} else {
			NIH_MUST (event_new (NULL,
				initial_event
				? initial_event
				: STARTUP_EVENT,
				NULL));
		}

	} else {
		sigset_t        mask;

		/* We have been re-exec'd. Don't emit an initial event
		 * as only Upstart is restarting - we don't want to restart
		 * the system (another reason being that we don't yet support
		 * upstart-in-initramfs to upstart-in-root-filesystem
		 * state-passing transitions).
		 */

		/* We're ok to receive signals again so restore signals
		 * disabled by the term_handler */
		sigemptyset (&mask);
		sigprocmask (SIG_SETMASK, &mask, NULL);

		/* Emit the Restarted signal so that any listening Instance Init
		 * knows that it needs to restart too.
		 */
		control_notify_restarted();
	}

	if (chroot_sessions)
		nih_debug ("Chroot Sessions enabled");

	/* Set us as the child subreaper.
	 * This ensures that even when init doesn't run as PID 1, it'll always be
	 * the ultimate parent of everything it spawns. */

#ifdef HAVE_SYS_PRCTL_H
	if (getpid () > 1 && prctl (PR_SET_CHILD_SUBREAPER, 1) < 0) {
		nih_warn ("%s: %s", _("Unable to register as subreaper"),
				  strerror (errno));

		NIH_MUST (event_new (NULL, "child-subreaper-failed", NULL));
	}
#endif

	/* Run through the loop at least once to deal with signals that were
	 * delivered to the previous process while the mask was set or to
	 * process the startup event we emitted.
	 */
	nih_main_loop_interrupt ();
	ret = nih_main_loop ();

	/* Cleanup */
	conf_destroy ();
	session_destroy ();
	control_cleanup ();

	return ret;
}


#ifndef DEBUG
/**
 * logger_kmsg:
 * @priority: priority of message being logged,
 * @message: message to log.
 *
 * Outputs the @message to the kernel log message socket prefixed with an
 * appropriate tag based on @priority, the program name and terminated with
 * a new line.
 *
 * Returns: zero on success, negative value on error.
 **/
static int
logger_kmsg (NihLogLevel priority,
	     const char *message)
{
	int             tag;
	int             fd;
	ssize_t         ret;
	size_t          remaining = -1;
	nih_local char *buffer = NULL;
	char           *p;

	nih_assert (message != NULL);

	switch (priority) {
	case NIH_LOG_DEBUG:
		tag = '7';
		break;
	case NIH_LOG_INFO:
		tag = '6';
		break;
	case NIH_LOG_MESSAGE:
		tag = '5';
		break;
	case NIH_LOG_WARN:
		tag = '4';
		break;
	case NIH_LOG_ERROR:
		tag = '3';
		break;
	case NIH_LOG_FATAL:
		tag = '2';
		break;
	default:
		tag = 'd';
	}

	fd = open ("/dev/kmsg", O_WRONLY | O_NOCTTY);
	if (fd < 0)
		return -1;

	buffer = nih_sprintf (NULL, "<%c>%s: %s\n", tag, program_name, message);
	if (! buffer)
		goto out;

	p = buffer;

	remaining = strlen (p);

	do {
		ret = write (fd, p, remaining);
		if (ret > 0) {
			p += ret;
			remaining -= ret;
		} else if (! ret || (ret < 0 && errno != EINTR)) {
			close (fd);
			return -1;
		}
	} while (remaining);

out:
	if (close (fd) < 0)
		return -1;

	return 0;
}


/**
 * crash_handler:
 * @signum: signal number received.
 *
 * Handle receiving the SEGV or ABRT signal, usually caused by one of
 * our own mistakes.  We deal with it by dumping core in a child process
 * and then killing the parent.
 *
 * Sadly there's no real alternative to the ensuing kernel panic.  Our
 * state is likely in tatters, so we can't sigjmp() anywhere "safe" or
 * re-exec since the system will be suddenly lobotomised.  We definitely
 * don't want to start a root shell or anything like that.  Best thing is
 * to just stop the whole thing and hope that bug report comes quickly.
 **/
static void
crash_handler (int signum)
{
	pid_t pid;

	nih_assert (args_copy[0] != NULL);

	pid = fork ();
	if (pid == 0) {
		struct sigaction act;
		struct rlimit    limit;
		sigset_t         mask;

		/* Mask out all signals */
		sigfillset (&mask);
		sigprocmask (SIG_SETMASK, &mask, NULL);

		/* Set the handler to the default so core is dumped */
		act.sa_handler = SIG_DFL;
		act.sa_flags = 0;
		sigemptyset (&act.sa_mask);
		sigaction (signum, &act, NULL);

		/* Don't limit the core dump size */
		limit.rlim_cur = RLIM_INFINITY;
		limit.rlim_max = RLIM_INFINITY;
		setrlimit (RLIMIT_CORE, &limit);

		/* Dump in the root directory */
		if (chdir ("/"))
			nih_warn ("%s: %s", _("Unable to set root directory"),
				  strerror (errno));

		/* Raise the signal again */
		raise (signum);

		/* Unmask so that we receive it */
		sigdelset (&mask, signum);
		sigprocmask (SIG_SETMASK, &mask, NULL);

		/* Wait for death */
		pause ();
		exit (0);
	} else if (pid > 0) {
		/* Wait for the core to be generated */
		waitpid (pid, NULL, 0);

		nih_fatal (_("Caught %s, core dumped"),
			   (signum == SIGSEGV
			    ? "segmentation fault" : "abort"));
	} else {
		nih_fatal (_("Caught %s, unable to dump core"),
			   (signum == SIGSEGV
			    ? "segmentation fault" : "abort"));
	}

	/* Goodbye, cruel world. */
	exit (signum);
}
#endif

/**
 * term_handler:
 * @data: unused,
 * @signal: signal caught.
 *
 * This is called when we receive the TERM signal, which instructs us
 * to reexec ourselves when running as PID 1, or to perform a controlled
 * exit when running as a Session Init.
 **/
static void
term_handler (void      *data,
	      NihSignal *signal)
{
	nih_assert (args_copy[0] != NULL);
	nih_assert (signal != NULL);

	if (user_mode) {
		quiesce (QUIESCE_REQUESTER_SYSTEM);
		return;
	}

	nih_warn (_("Re-executing %s"), args_copy[0]);
	stateful_reexec ();
}


#ifndef DEBUG
/**
 * cad_handler:
 * @data: unused,
 * @signal: signal that called this handler.
 *
 * Handle having received the SIGINT signal, sent to us when somebody
 * presses Ctrl-Alt-Delete on the console.  We just generate a
 * ctrlaltdel event.
 **/
static void
cad_handler (void      *data,
	     NihSignal *signal)
{
	NIH_MUST (event_new (NULL, CTRLALTDEL_EVENT, NULL));
}

/**
 * kbd_handler:
 * @data: unused,
 * @signal: signal that called this handler.
 *
 * Handle having received the SIGWINCH signal, sent to us when somebody
 * presses Alt-UpArrow on the console.  We just generate a
 * kbdrequest event.
 **/
static void
kbd_handler (void      *data,
	     NihSignal *signal)
{
	NIH_MUST (event_new (NULL, KBDREQUEST_EVENT, NULL));
}

/**
 * pwr_handler:
 * @data: unused,
 * @signal: signal that called this handler.
 *
 * Handle having received the SIGPWR signal, sent to us when powstatd
 * changes the /etc/powerstatus file.  We just generate a
 * power-status-changed event and jobs read the file.
 **/
static void
pwr_handler (void      *data,
	     NihSignal *signal)
{
	NIH_MUST (event_new (NULL, PWRSTATUS_EVENT, NULL));
}

/**
 * hup_handler:
 * @data: unused,
 * @signal: signal that called this handler.
 *
 * Handle having received the SIGHUP signal, which we use to instruct us to
 * reload our configuration.
 **/
static void
hup_handler (void      *data,
	     NihSignal *signal)
{
	nih_info (_("Reloading configuration"));
	conf_reload ();
}

/**
 * usr1_handler:
 * @data: unused,
 * @signal: signal that called this handler.
 *
 * Handle having received the SIGUSR signal, which we use to instruct us to
 * reconnect to D-Bus.
 **/
static void
usr1_handler (void      *data,
	      NihSignal *signal)
{
	nih_assert (! user_mode);

	if (disable_dbus)
		return;

	if (! control_bus) {
		char *dbus_bus_name;

		dbus_bus_name = dbus_bus_type == DBUS_BUS_SESSION
			? "session" : "system";

		nih_info (_("Reconnecting to D-Bus %s bus"),
				dbus_bus_name);

		if (control_bus_open () < 0) {
			NihError *err;

			err = nih_error_get ();
			nih_warn (_("Unable to connect to the D-Bus %s bus: %s"),
					dbus_bus_name, err->message);
			nih_free (err);
		}
	}
}
#endif /* DEBUG */

/**
 * handle_confdir:
 *
 * Determine where system configuration files should be loaded from
 * if not specified on the command-line.
 **/
static void
handle_confdir (void)
{
	char  *dir;

	nih_assert (conf_dirs);

	/* user has already specified directory on command-line */
	if (conf_dirs[0])
		return;

	if (user_mode)
		return;

	dir = getenv (CONFDIR_ENV);

	NIH_MUST (nih_str_array_add (&conf_dirs, NULL, NULL, dir ? dir : CONFDIR));
}

/**
 * handle_logdir:
 *
 * Determine directory where job log files should be written to.
 **/
static void
handle_logdir (void)
{
	char *dir;

	/* user has already specified directory on command-line */
	if (log_dir)
		goto out;

	if (user_mode) {
		log_dir = get_user_log_dir ();
		return;
	}

	log_dir = JOB_LOGDIR;

	dir = getenv (LOGDIR_ENV);
	if (! dir)
		return;

	log_dir = dir;

out:
	nih_debug ("Using alternate log directory %s",
			log_dir);
}

/**  
 * NihOption setter function to handle selection of default console
 * type.
 *
 * Returns: 0 on success, -1 on invalid console type.
 **/
static int
console_type_setter (NihOption *option, const char *arg)
{
	 nih_assert (option);

	 default_console = (int)job_class_console_type (arg);

	 if (default_console == -1) {
		 nih_fatal ("%s: %s", _("invalid console type specified"), arg);
		 return -1;
	 }

	 return 0;
}

/**  
 * NihOption setter function to handle selection of configuration file
 * directories.
 *
 * Returns: 0 on success, -1 on invalid console type.
 **/
static int
conf_dir_setter (NihOption *option, const char *arg)
{
	nih_assert (conf_dirs);
	nih_assert (option);

	NIH_MUST (nih_str_array_add (&conf_dirs, NULL, NULL, arg));

	return 0;
}

/**  
 * NihOption setter function to handle selection of configuration file
 * directories.
 *
 * Returns: 0 on success, -1 on invalid console type.
 **/
static int
prepend_conf_dir_setter (NihOption *option, const char *arg)
{
	nih_assert (prepend_conf_dirs);
	nih_assert (option);

	NIH_MUST (nih_str_array_add (&prepend_conf_dirs, NULL, NULL, arg));

	return 0;
}

/**  
 * NihOption setter function to handle selection of configuration file
 * directories.
 *
 * Returns: 0 on success, -1 on invalid console type.
 **/
static int
append_conf_dir_setter (NihOption *option, const char *arg)
{
	nih_assert (append_conf_dirs);
	nih_assert (option);

	NIH_MUST (nih_str_array_add (&append_conf_dirs, NULL, NULL, arg));

	return 0;
}