libdaemon/examples/testd.c

/***
  This file is part of libdaemon.

  Copyright 2003-2008 Lennart Poettering

  Permission is hereby granted, free of charge, to any person obtaining a copy
  of this software and associated documentation files (the "Software"), to deal
  in the Software without restriction, including without limitation the rights
  to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
  copies of the Software, and to permit persons to whom the Software is
  furnished to do so, subject to the following conditions:

  The above copyright notice and this permission notice shall be included in
  all copies or substantial portions of the Software.

  THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
  AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
  OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
  SOFTWARE.

***/

#include <signal.h>
#include <errno.h>
#include <string.h>
#include <sys/types.h>
#include <sys/time.h>
#include <sys/unistd.h>
#include <sys/select.h>

#include <libdaemon/dfork.h>
#include <libdaemon/dsignal.h>
#include <libdaemon/dlog.h>
#include <libdaemon/dpid.h>
#include <libdaemon/dexec.h>

int main(int argc, char *argv[]) {
    pid_t pid;

    /* Reset signal handlers */
    if (daemon_reset_sigs(-1) < 0) {
        daemon_log(LOG_ERR, "Failed to reset all signal handlers: %s", strerror(errno));
        return 1;
    }

    /* Unblock signals */
    if (daemon_unblock_sigs(-1) < 0) {
        daemon_log(LOG_ERR, "Failed to unblock all signals: %s", strerror(errno));
        return 1;
    }

    /* Set indetification string for the daemon for both syslog and PID file */
    daemon_pid_file_ident = daemon_log_ident = daemon_ident_from_argv0(argv[0]);

    /* Check if we are called with -k parameter */
    if (argc >= 2 && !strcmp(argv[1], "-k")) {
        int ret;

        /* Kill daemon with SIGTERM */

        /* Check if the new function daemon_pid_file_kill_wait() is available, if it is, use it. */
        if ((ret = daemon_pid_file_kill_wait(SIGTERM, 5)) < 0)
            daemon_log(LOG_WARNING, "Failed to kill daemon: %s", strerror(errno));

        return ret < 0 ? 1 : 0;
    }

    /* Check that the daemon is not rung twice a the same time */
    if ((pid = daemon_pid_file_is_running()) >= 0) {
        daemon_log(LOG_ERR, "Daemon already running on PID file %u", pid);
        return 1;
    }

    /* Prepare for return value passing from the initialization procedure of the daemon process */
    if (daemon_retval_init() < 0) {
        daemon_log(LOG_ERR, "Failed to create pipe.");
        return 1;
    }

    /* Do the fork */
    if ((pid = daemon_fork()) < 0) {

        /* Exit on error */
        daemon_retval_done();
        return 1;

    } else if (pid) { /* The parent */
        int ret;

        /* Wait for 20 seconds for the return value passed from the daemon process */
        if ((ret = daemon_retval_wait(20)) < 0) {
            daemon_log(LOG_ERR, "Could not recieve return value from daemon process: %s", strerror(errno));
            return 255;
        }

        daemon_log(ret != 0 ? LOG_ERR : LOG_INFO, "Daemon returned %i as return value.", ret);
        return ret;

    } else { /* The daemon */
        int fd, quit = 0;
        fd_set fds;

        /* Close FDs */
        if (daemon_close_all(-1) < 0) {
            daemon_log(LOG_ERR, "Failed to close all file descriptors: %s", strerror(errno));

            /* Send the error condition to the parent process */
            daemon_retval_send(1);
            goto finish;
        }

        /* Create the PID file */
        if (daemon_pid_file_create() < 0) {
            daemon_log(LOG_ERR, "Could not create PID file (%s).", strerror(errno));
            daemon_retval_send(2);
            goto finish;
        }

        /* Initialize signal handling */
        if (daemon_signal_init(SIGINT, SIGTERM, SIGQUIT, SIGHUP, 0) < 0) {
            daemon_log(LOG_ERR, "Could not register signal handlers (%s).", strerror(errno));
            daemon_retval_send(3);
            goto finish;
        }

        /*... do some further init work here */


        /* Send OK to parent process */
        daemon_retval_send(0);

        daemon_log(LOG_INFO, "Sucessfully started");

        /* Prepare for select() on the signal fd */
        FD_ZERO(&fds);
        fd = daemon_signal_fd();
        FD_SET(fd, &fds);

        while (!quit) {
            fd_set fds2 = fds;

            /* Wait for an incoming signal */
            if (select(FD_SETSIZE, &fds2, 0, 0, 0) < 0) {

                /* If we've been interrupted by an incoming signal, continue */
                if (errno == EINTR)
                    continue;

                daemon_log(LOG_ERR, "select(): %s", strerror(errno));
                break;
            }

            /* Check if a signal has been recieved */
            if (FD_ISSET(fd, &fds2)) {
                int sig;

                /* Get signal */
                if ((sig = daemon_signal_next()) <= 0) {
                    daemon_log(LOG_ERR, "daemon_signal_next() failed: %s", strerror(errno));
                    break;
                }

                /* Dispatch signal */
                switch (sig) {

                    case SIGINT:
                    case SIGQUIT:
                    case SIGTERM:
                        daemon_log(LOG_WARNING, "Got SIGINT, SIGQUIT or SIGTERM.");
                        quit = 1;
                        break;

                    case SIGHUP:
                        daemon_log(LOG_INFO, "Got a HUP");
                        daemon_exec("/", NULL, "/bin/ls", "ls", (char*) NULL);
                        break;

                }
            }
        }

        /* Do a cleanup */
finish:
        daemon_log(LOG_INFO, "Exiting...");
        daemon_retval_send(255);
        daemon_signal_done();
        daemon_pid_file_remove();

        return 0;
    }
}