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(nochdir, noclose)
  45         int nochdir, noclose;
  46 {
  47         int fd;
  48
  49         switch (__fork()) {
  50         case -1:
  51                 return (-1);
  52         case 0:
  53                 break;
  54         default:
  55                 _exit(0);
  56         }
  57
  58         if (__setsid() == -1)
  59                 return (-1);
  60
  61         if (!nochdir)
  62                 (void)__chdir("/");
  63
  64         if (!noclose
  65             && (fd = open_not_cancel(_PATH_DEVNULL, O_RDWR, 0)) != -1) {
  66                 struct stat64 st;
  67
  68                 if (__builtin_expect (__fxstat64 (_STAT_VER, fd, &st), 0) == 0
  69                     && __builtin_expect (S_ISCHR (st.st_mode), 1) != 0
  70 #if defined DEV_NULL_MAJOR && defined DEV_NULL_MINOR
  71                     && st.st_rdev == makedev (DEV_NULL_MAJOR, DEV_NULL_MINOR)
  72 #endif
  73                     ) {
  74                         (void)__dup2(fd, STDIN_FILENO);
  75                         (void)__dup2(fd, STDOUT_FILENO);
  76                         (void)__dup2(fd, STDERR_FILENO);
  77                         if (fd > 2)
  78                                 (void)__close (fd);
  79                 } else {
  80                         close_not_cancel_no_status (fd);
  81                         return -1;
  82                 }
  83         }
  84         return (0);
  85 }