lib/util/become_daemon.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Samba utility functions
   4    Copyright (C) Andrew Tridgell 1992-1998
   5    Copyright (C) Jeremy Allison 2001-2002
   6    Copyright (C) Simo Sorce 2001
   7    Copyright (C) Jim McDonough (jmcd@us.ibm.com)  2003.
   8    Copyright (C) James J Myers 2003
   9
  10    This program is free software; you can redistribute it and/or modify
  11    it under the terms of the GNU General Public License as published by
  12    the Free Software Foundation; either version 3 of the License, or
  13    (at your option) any later version.
  14
  15    This program is distributed in the hope that it will be useful,
  16    but WITHOUT ANY WARRANTY; without even the implied warranty of
  17    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  18    GNU General Public License for more details.
  19
  20    You should have received a copy of the GNU General Public License
  21    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  22 */
  23
  24 #include "includes.h"
  25 #include "system/filesys.h"
  26 #include "system/locale.h"
  27
  28 /*******************************************************************
  29  Close the low 3 fd's and open dev/null in their place.
  30 ********************************************************************/
  31 static void close_low_fds(bool stderr_too)
  32 {
  33 #ifndef VALGRIND
  34         int fd;
  35         int i;
  36
  37         close(0);
  38         close(1);
  39
  40         if (stderr_too)
  41                 close(2);
  42
  43         /* try and use up these file descriptors, so silly
  44                 library routines writing to stdout etc won't cause havoc */
  45         for (i=0;i<3;i++) {
  46                 if (i == 2 && !stderr_too)
  47                         continue;
  48
  49                 fd = open("/dev/null",O_RDWR,0);
  50                 if (fd < 0)
  51                         fd = open("/dev/null",O_WRONLY,0);
  52                 if (fd < 0) {
  53                         DEBUG(0,("Can't open /dev/null\n"));
  54                         return;
  55                 }
  56                 if (fd != i) {
  57                         DEBUG(0,("Didn't get file descriptor %d\n",i));
  58                         return;
  59                 }
  60         }
  61 #endif
  62 }
  63
  64 /**
  65  Become a daemon, discarding the controlling terminal.
  66 **/
  67
  68 _PUBLIC_ void become_daemon(bool Fork)
  69 {
  70         if (Fork) {
  71                 if (fork()) {
  72                         _exit(0);
  73                 }
  74         }
  75
  76   /* detach from the terminal */
  77 #ifdef HAVE_SETSID
  78         setsid();
  79 #elif defined(TIOCNOTTY)
  80         {
  81                 int i = open("/dev/tty", O_RDWR, 0);
  82                 if (i != -1) {
  83                         ioctl(i, (int) TIOCNOTTY, (char *)0);
  84                         close(i);
  85                 }
  86         }
  87 #endif /* HAVE_SETSID */
  88
  89         /* Close fd's 0,1,2. Needed if started by rsh */
  90         close_low_fds(false);  /* Don't close stderr, let the debug system
  91                                   attach it to the logfile */
  92 }
  93