source: titan/minidlna-1.0.22/daemonize.c @ 13567

/* $Id: daemonize.c,v 1.4 2011/02/15 02:46:28 jmaggard Exp $ */
/* MiniUPnP project
 * http://miniupnp.free.fr/ or http://miniupnp.tuxfamily.org/
 *
 * Copyright (c) 2006, Thomas Bernard
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * The name of the author may not be used to endorse or promote products
 *       derived from this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */
#include <sys/types.h>
#include <sys/stat.h>
#include <unistd.h>
#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <signal.h>

#include "daemonize.h"
#include "config.h"
#include "log.h"

#ifndef USE_DAEMON

int
daemonize(void)
{
        int pid, i;

        switch(fork())
        {
        /* fork error */
        case -1:
                perror("fork()");
                exit(1);
        
        /* child process */
        case 0:
                /* obtain a new process group */
                if( (pid = setsid()) < 0)
                {
                        perror("setsid()");
                        exit(1);
                }

                /* close all descriptors */
                for (i=getdtablesize();i>=0;--i) close(i);              

                i = open("/dev/null",O_RDWR); /* open stdin */
                dup(i); /* stdout */
                dup(i); /* stderr */

                umask(027);
                chdir("/"); /* chdir to /tmp ? */                       

                return pid;

        /* parent process */
        default:
                exit(0);
        }
}
#endif

int
writepidfile(const char * fname, int pid)
{
        char pidstring[16];
        int pidstringlen;
        int pidfile;

        if(!fname || (strlen(fname) == 0))
                return -1;
        
        if( (pidfile = open(fname, O_WRONLY|O_CREAT, 0644)) < 0)
        {
                DPRINTF(E_ERROR, L_GENERAL, "Unable to open pidfile for writing %s: %s\n", fname, strerror(errno));
                return -1;
        }

        pidstringlen = snprintf(pidstring, sizeof(pidstring), "%d\n", pid);
        if(pidstringlen <= 0)
        {
                DPRINTF(E_ERROR, L_GENERAL, 
                        "Unable to write to pidfile %s: snprintf(): FAILED\n", fname);
                close(pidfile);
                return -1;
        }
        else
        {
                if(write(pidfile, pidstring, pidstringlen) < 0)
                        DPRINTF(E_ERROR, L_GENERAL, "Unable to write to pidfile %s: %s\n", fname, strerror(errno));
        }

        close(pidfile);

        return 0;
}

int
checkforrunning(const char * fname)
{
        char buffer[64];
        int pidfile;
        pid_t pid;

        if(!fname || (strlen(fname) == 0))
                return -1;

        if( (pidfile = open(fname, O_RDONLY)) < 0)
                return 0;
        
        memset(buffer, 0, 64);
        
        if(read(pidfile, buffer, 63))
        {
                if( (pid = atol(buffer)) > 0)
                {
                        if(!kill(pid, 0))
                        {
                                close(pidfile);
                                return -2;
                        }
                }
        }
        
        close(pidfile);
        
        return 0;
}