misc/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
  30 #if defined(LIBC_SCCS) && !defined(lint)
  31 static char sccsid[] = "@(#)daemon.c    8.1 (Berkeley) 6/4/93";
  32 #endif /* LIBC_SCCS and not lint */
  33
  34 #include <errno.h>
  35 #include <fcntl.h>
  36 #include <paths.h>
  37 #include <unistd.h>
  38 #include <sys/stat.h>
  39
  40 #include <device-nrs.h>
  41 #include <not-cancel.h>
  42
  43 int
  44 daemon (int nochdir, int noclose)
  45 {
  46         int fd;
  47
  48         switch (__fork()) {
  49         case -1:
  50                 return (-1);
  51         case 0:
  52                 break;
  53         default:
  54                 _exit(0);
  55         }
  56
  57         if (__setsid() == -1)
  58                 return (-1);
  59
  60         if (!nochdir)
  61                 (void)__chdir("/");
  62
  63         if (!noclose) {
  64                 struct stat64 st;
  65
  66                 if ((fd = open_not_cancel(_PATH_DEVNULL, O_RDWR, 0)) != -1
  67                     && (__builtin_expect (__fxstat64 (_STAT_VER, fd, &st), 0)
  68                         == 0)) {
  69                         if (__builtin_expect (S_ISCHR (st.st_mode), 1) != 0
  70 #if defined DEV_NULL_MAJOR && defined DEV_NULL_MINOR
  71                             && (st.st_rdev
  72                                 == makedev (DEV_NULL_MAJOR, DEV_NULL_MINOR))
  73 #endif
  74                             ) {
  75                                 (void)__dup2(fd, STDIN_FILENO);
  76                                 (void)__dup2(fd, STDOUT_FILENO);
  77                                 (void)__dup2(fd, STDERR_FILENO);
  78                                 if (fd > 2)
  79                                         (void)__close (fd);
  80                         } else {
  81                                 /* We must set an errno value since no
  82                                    function call actually failed.  */
  83                                 close_not_cancel_no_status (fd);
  84                                 __set_errno (ENODEV);
  85                                 return -1;
  86                         }
  87                 } else {
  88                         close_not_cancel_no_status (fd);
  89                         return -1;
  90                 }
  91         }
  92         return (0);
  93 }