daemons/cmirrord/clogd.c

/*
 * Copyright (C) 2004-2009 Red Hat, Inc. All rights reserved.
 *
 * This copyrighted material is made available to anyone wishing to use,
 * modify, copy, or redistribute it subject to the terms and conditions
 * of the GNU General Public License v.2.
 *
 * 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
 */
#include "logging.h"
#include "common.h"
#include "functions.h"
#include "link_mon.h"
#include "local.h"

#include <getopt.h>
#include <errno.h>
#include <fcntl.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/wait.h>
#include <unistd.h>

static volatile sig_atomic_t exit_now = 0;
/* FIXME Review signal handling.  Should be volatile sig_atomic_t */
static sigset_t signal_mask;
static volatile sig_atomic_t signal_received;

static void process_signals(void);
static void daemonize(void);
static void init_all(void);
static void cleanup_all(void);

static void usage (FILE *dest)
{
	fprintf (dest, "Usage: cmirrord [options]\n"
		 "   -f, --foreground    stay in the foreground, log to the terminal\n"
		 "   -h, --help          print this help\n");
}

int main(int argc, char *argv[])
{
	int foreground_mode = 0;
	struct option longopts[] = {
		{ "foreground", no_argument, NULL, 'f' },
		{ "help"      , no_argument, NULL, 'h' },
		{ 0, 0, 0, 0 }
	};
	int opt;

	while ((opt = getopt_long (argc, argv, "fh", longopts, NULL)) != -1) {
		switch (opt) {
		case 'f':
			foreground_mode = 1;
			break;
		case 'h':
			usage (stdout);
			exit (0);
		default:
			usage (stderr);
			exit (2);
		}
	}
	if (optind < argc) {
		usage (stderr);
		exit (2);
	}

	if (!foreground_mode)
		daemonize();

	init_all();

	/* Parent can now exit, we're ready to handle requests */
	if (!foreground_mode)
		kill(getppid(), SIGTERM);

	LOG_PRINT("Starting cmirrord:");
	LOG_PRINT(" Built: "__DATE__" "__TIME__"\n");
	LOG_DBG(" Compiled with debugging.");

	while (!exit_now) {
		links_monitor();

		links_issue_callbacks();

		process_signals();
	}
	exit(EXIT_SUCCESS);
}

/*
 * parent_exit_handler: exit the parent
 * @sig: the signal
 *
 */
static void parent_exit_handler(int sig __attribute__((unused)))
{
	exit_now = 1;
}

static void sig_handler(int sig)
{
	/* FIXME Races - don't touch signal_mask here. */
	sigaddset(&signal_mask, sig);
	signal_received = 1;
}

static void process_signal(int sig){
	int r = 0;

	switch(sig) {
	case SIGINT:
	case SIGQUIT:
	case SIGTERM:
	case SIGHUP:
		r += log_status();
		break;
	case SIGUSR1:
	case SIGUSR2:
		log_debug();
		/*local_debug();*/
		cluster_debug();
		return;
	default:
		LOG_PRINT("Unknown signal received... ignoring");
		return;
	}

	if (!r) {
		LOG_DBG("No current cluster logs... safe to exit.");
		cleanup_all();
		exit(EXIT_SUCCESS);
	}

	LOG_ERROR("Cluster logs exist.  Refusing to exit.");
}

static void process_signals(void)
{
	int x;

	if (!signal_received)
		return;

	signal_received = 0;

	for (x = 1; x < _NSIG; x++) {
		if (sigismember(&signal_mask, x)) {
			sigdelset(&signal_mask, x);
			process_signal(x);
		}
	}
}

static void remove_lockfile(void)
{
	if (unlink(CMIRRORD_PIDFILE))
		LOG_ERROR("Unable to remove \"" CMIRRORD_PIDFILE "\" %s", strerror(errno));
}

/*
 * daemonize
 *
 * Performs the steps necessary to become a daemon.
 */
static void daemonize(void)
{
	int pid;
	int status;
	int devnull;

	if ((devnull = open("/dev/null", O_RDWR)) == -1) {
		LOG_ERROR("Can't open /dev/null: %s", strerror(errno));
		exit(EXIT_FAILURE);
	}

	signal(SIGTERM, &parent_exit_handler);

	pid = fork();

	if (pid < 0) {
		LOG_ERROR("Unable to fork()");
		exit(EXIT_FAILURE);
	}

	if (pid) {
		/* Parent waits here for child to get going */
		while (!waitpid(pid, &status, WNOHANG) && !exit_now);
		if (exit_now)
			exit(EXIT_SUCCESS);

		switch (WEXITSTATUS(status)) {
		case EXIT_LOCKFILE:
			LOG_ERROR("Failed to create lockfile");
			LOG_ERROR("Process already running?");
			break;
		case EXIT_KERNEL_SOCKET:
			LOG_ERROR("Unable to create netlink socket");
			break;
		case EXIT_KERNEL_BIND:
			LOG_ERROR("Unable to bind to netlink socket");
			break;
		case EXIT_KERNEL_SETSOCKOPT:
			LOG_ERROR("Unable to setsockopt on netlink socket");
			break;
		case EXIT_CLUSTER_CKPT_INIT:
			LOG_ERROR("Unable to initialize checkpoint service");
			LOG_ERROR("Has the cluster infrastructure been started?");
			break;
		case EXIT_FAILURE:
			LOG_ERROR("Failed to start: Generic error");
			break;
		default:
			LOG_ERROR("Failed to start: Unknown error");
			break;
		}
		exit(EXIT_FAILURE);
	}

	setsid();
	if (chdir("/")) {
		LOG_ERROR("Failed to chdir /: %s", strerror(errno));
		exit(EXIT_FAILURE);
	}

	umask(0);

	if (close(0) || close(1) || close(2)) {
		LOG_ERROR("Failed to close terminal FDs");
		exit(EXIT_FAILURE);
	}

	if ((dup2(devnull, 0) < 0) || /* reopen stdin */
	    (dup2(devnull, 1) < 0) || /* reopen stdout */
	    (dup2(devnull, 2) < 0))   /* reopen stderr */
		exit(EXIT_FAILURE);

	if ((devnull > STDERR_FILENO) && close(devnull)) {
		LOG_ERROR("Failed to close descriptor %d: %s",
			  devnull, strerror(errno));
		exit(EXIT_FAILURE);
	}

	LOG_OPEN("cmirrord", LOG_PID, LOG_DAEMON);
}

/*
 * init_all
 *
 * Initialize modules.  Exit on failure.
 */
static void init_all(void)
{
	int r;

	(void) dm_prepare_selinux_context(CMIRRORD_PIDFILE, S_IFREG);
	if (dm_create_lockfile(CMIRRORD_PIDFILE) == 0)
		exit(EXIT_LOCKFILE);
	(void) dm_prepare_selinux_context(NULL, 0);

	atexit(remove_lockfile);

	/* FIXME Replace with sigaction. (deprecated) */
	signal(SIGINT, &sig_handler);
	signal(SIGQUIT, &sig_handler);
	signal(SIGTERM, &sig_handler);
	signal(SIGHUP, &sig_handler);
	signal(SIGPIPE, SIG_IGN);
	signal(SIGUSR1, &sig_handler);
	signal(SIGUSR2, &sig_handler);
	sigemptyset(&signal_mask);
	signal_received = 0;

	if ((r = init_local()) ||
	    (r = init_cluster())) {
		exit(r);
	}
}

/*
 * cleanup_all
 *
 * Clean up before exiting
 */
static void cleanup_all(void)
{
	cleanup_local();
	cleanup_cluster();
}