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     {
  50     case -1:
  51       return -1;
  52
  53     case 0:
  54       break;
  55
  56     default:
  57       _exit (0);
  58     }
  59
  60   if (__setsid () == -1)
  61     return -1;
  62
  63   if (!nochdir)
  64     (void) __chdir ("/");
  65
  66   if (!noclose)
  67     {
  68       struct __stat64_t64 st;
  69
  70       fd = __open_nocancel (_PATH_DEVNULL, O_RDWR, 0);
  71       if (fd != -1 && __glibc_likely (__fstat64_time64 (fd, &st) == 0))
  72         {
  73           if (__builtin_expect (S_ISCHR (st.st_mode), 1) != 0
  74 #if defined DEV_NULL_MAJOR && defined DEV_NULL_MINOR
  75               && (st.st_rdev == makedev (DEV_NULL_MAJOR, DEV_NULL_MINOR))
  76 #endif
  77              )
  78             {
  79               (void) __dup2 (fd, STDIN_FILENO);
  80               (void) __dup2 (fd, STDOUT_FILENO);
  81               (void) __dup2 (fd, STDERR_FILENO);
  82               if (fd > 2)
  83                 (void) __close (fd);
  84             }
  85           else
  86             {
  87               /* We must set an errno value since no function call
  88                  actually failed.  */
  89               __close_nocancel_nostatus (fd);
  90               __set_errno (ENODEV);
  91               return -1;
  92             }
  93         }
  94       else
  95         {
  96           __close_nocancel_nostatus (fd);
  97           return -1;
  98         }
  99     }
 100
 101   return 0;
 102 }