src/libs/bsd/daemon.c

   1 /*
   2  * Copyright 2007, Haiku, Inc. All Rights Reserved.
   3  * Distributed under the terms of the MIT License.
   4  *
   5  * Authors:
   6  *              Axel Dörfler, axeld@pinc-software.de
   7  */
   8
   9 #include <fcntl.h>
  10 #include <stdlib.h>
  11 #include <signal.h>
  12 #include <unistd.h>
  13
  14
  15 static void
  16 restore_old_sighup(int result, struct sigaction *action)
  17 {
  18         if (result != -1)
  19                 sigaction(SIGHUP, action, NULL);
  20 }
  21
  22
  23 int
  24 daemon(int noChangeDir, int noClose)
  25 {
  26         struct sigaction oldAction, action;
  27         int oldActionResult;
  28         pid_t newGroup;
  29         pid_t pid;
  30
  31         /* Ignore eventually send SIGHUPS on parent exit */
  32         sigemptyset(&action.sa_mask);
  33         action.sa_handler = SIG_IGN;
  34         action.sa_flags = 0;
  35         oldActionResult = sigaction(SIGHUP, &action, &oldAction);
  36
  37         pid = fork();
  38         if (pid == -1) {
  39                 restore_old_sighup(oldActionResult, &oldAction);
  40                 return -1;
  41         }
  42         if (pid > 0) {
  43                 // we're the parent - let's exit
  44                 exit(0);
  45         }
  46
  47         newGroup = setsid();
  48         restore_old_sighup(oldActionResult, &oldAction);
  49
  50         if (newGroup == -1)
  51                 return -1;
  52
  53         if (!noChangeDir)
  54                 chdir("/");
  55
  56         if (!noClose) {
  57                 int fd = open("/dev/null", O_RDWR);
  58                 if (fd != -1) {
  59                         dup2(fd, STDIN_FILENO);
  60                         dup2(fd, STDOUT_FILENO);
  61                         dup2(fd, STDERR_FILENO);
  62                         if (fd > STDERR_FILENO)
  63                                 close(fd);
  64                 }
  65         }
  66
  67         return 0;
  68 }