lib/libc/gen/daemon.c

   1 /*-
   2  * Copyright (c) 1990, 1993
   3  *      The Regents of the University of California.  All rights reserved.
   4  *
   5  * Redistribution and use in source and binary forms, with or without
   6  * modification, are permitted provided that the following conditions
   7  * are met:
   8  * 1. Redistributions of source code must retain the above copyright
   9  *    notice, this list of conditions and the following disclaimer.
  10  * 2. Redistributions in binary form must reproduce the above copyright
  11  *    notice, this list of conditions and the following disclaimer in the
  12  *    documentation and/or other materials provided with the distribution.
  13  * 4. Neither the name of the University nor the names of its contributors
  14  *    may be used to endorse or promote products derived from this software
  15  *    without specific prior written permission.
  16  *
  17  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  18  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  19  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  20  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  21  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  22  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  23  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  24  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  25  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  26  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  27  * SUCH DAMAGE.
  28  *
  29  * @(#)daemon.c 8.1 (Berkeley) 6/4/93
  30  * $FreeBSD: src/lib/libc/gen/daemon.c,v 1.8 2007/01/09 00:27:53 imp Exp $
  31  * $DragonFly: src/lib/libc/gen/daemon.c,v 1.4 2005/04/26 15:57:39 joerg Exp $
  32  */
  33
  34 #include "namespace.h"
  35 #include <errno.h>
  36 #include <fcntl.h>
  37 #include <paths.h>
  38 #include <stdlib.h>
  39 #include <signal.h>
  40 #include <unistd.h>
  41 #include "un-namespace.h"
  42
  43 int
  44 daemon(int nochdir, int noclose)
  45 {
  46         struct sigaction osa, sa;
  47         int fd;
  48         pid_t newgrp;
  49         int oerrno;
  50         int osa_ok;
  51
  52         /* A SIGHUP may be thrown when the parent exits below. */
  53         sigemptyset(&sa.sa_mask);
  54         sa.sa_handler = SIG_IGN;
  55         sa.sa_flags = 0;
  56         osa_ok = _sigaction(SIGHUP, &sa, &osa);
  57
  58         switch (fork()) {
  59         case -1:
  60                 return (-1);
  61         case 0:
  62                 break;
  63         default:
  64                 _exit(0);
  65         }
  66
  67         newgrp = setsid();
  68         oerrno = errno;
  69         if (osa_ok != -1)
  70                 _sigaction(SIGHUP, &osa, NULL);
  71
  72         if (newgrp == -1) {
  73                 errno = oerrno;
  74                 return (-1);
  75         }
  76
  77         if (!nochdir)
  78                 chdir("/");
  79
  80         if (!noclose && (fd = _open(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
  81                 _dup2(fd, STDIN_FILENO);
  82                 _dup2(fd, STDOUT_FILENO);
  83                 _dup2(fd, STDERR_FILENO);
  84                 if (fd > 2)
  85                         _close(fd);
  86         }
  87         return (0);
  88 }