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
  32 _PUBLIC_ void close_low_fds(bool stderr_too)
  33 {
  34 #ifndef VALGRIND
  35         int fd;
  36         int i;
  37
  38         close(0);
  39         close(1);
  40
  41         if (stderr_too)
  42                 close(2);
  43
  44         /* try and use up these file descriptors, so silly
  45                 library routines writing to stdout etc won't cause havoc */
  46         for (i=0;i<3;i++) {
  47                 if (i == 2 && !stderr_too)
  48                         continue;
  49
  50                 fd = open("/dev/null",O_RDWR,0);
  51                 if (fd < 0)
  52                         fd = open("/dev/null",O_WRONLY,0);
  53                 if (fd < 0) {
  54                         DEBUG(0,("Can't open /dev/null\n"));
  55                         return;
  56                 }
  57                 if (fd != i) {
  58                         DEBUG(0,("Didn't get file descriptor %d\n",i));
  59                         return;
  60                 }
  61         }
  62 #endif
  63 }
  64
  65 /****************************************************************************
  66  Become a daemon, discarding the controlling terminal.
  67 ****************************************************************************/
  68
  69 _PUBLIC_ void become_daemon(bool do_fork, bool no_process_group, bool log_stdout)
  70 {
  71         if (do_fork) {
  72                 if (sys_fork()) {
  73                         _exit(0);
  74                 }
  75         }
  76
  77         /* detach from the terminal */
  78 #ifdef HAVE_SETSID
  79         if (!no_process_group) setsid();
  80 #elif defined(TIOCNOTTY)
  81         if (!no_process_group) {
  82                 int i = sys_open("/dev/tty", O_RDWR, 0);
  83                 if (i != -1) {
  84                         ioctl(i, (int) TIOCNOTTY, (char *)0);
  85                         close(i);
  86                 }
  87         }
  88 #endif /* HAVE_SETSID */
  89
  90         if (!log_stdout) {
  91                 /* Close fd's 0,1,2. Needed if started by rsh */
  92                 close_low_fds(false);  /* Don't close stderr, let the debug system
  93                                           attach it to the logfile */
  94         }
  95 }