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 stdin_too, bool stdout_too, bool stderr_too)
  33 {
  34 #ifndef VALGRIND
  35         int fd;
  36         int i;
  37
  38         if (stdin_too)
  39                 close(0);
  40         if (stdout_too)
  41                 close(1);
  42
  43         if (stderr_too)
  44                 close(2);
  45
  46         /* try and use up these file descriptors, so silly
  47                 library routines writing to stdout etc won't cause havoc */
  48         for (i=0;i<3;i++) {
  49                 if (i == 0 && !stdin_too)
  50                         continue;
  51                 if (i == 1 && !stdout_too)
  52                         continue;
  53                 if (i == 2 && !stderr_too)
  54                         continue;
  55
  56                 fd = open("/dev/null",O_RDWR,0);
  57                 if (fd < 0)
  58                         fd = open("/dev/null",O_WRONLY,0);
  59                 if (fd < 0) {
  60                         DEBUG(0,("Can't open /dev/null\n"));
  61                         return;
  62                 }
  63                 if (fd != i) {
  64                         DEBUG(0,("Didn't get file descriptor %d\n",i));
  65                         return;
  66                 }
  67         }
  68 #endif
  69 }
  70
  71 /****************************************************************************
  72  Become a daemon, discarding the controlling terminal.
  73 ****************************************************************************/
  74
  75 _PUBLIC_ void become_daemon(bool do_fork, bool no_process_group, bool log_stdout)
  76 {
  77         if (do_fork) {
  78                 if (fork()) {
  79                         _exit(0);
  80                 }
  81         }
  82
  83         /* detach from the terminal */
  84 #ifdef HAVE_SETSID
  85         if (!no_process_group) setsid();
  86 #elif defined(TIOCNOTTY)
  87         if (!no_process_group) {
  88                 int i = open("/dev/tty", O_RDWR, 0);
  89                 if (i != -1) {
  90                         ioctl(i, (int) TIOCNOTTY, (char *)0);
  91                         close(i);
  92                 }
  93         }
  94 #endif /* HAVE_SETSID */
  95
  96         /* Close fd's 0,1,2 as appropriate. Needed if started by rsh. */
  97         /* stdin must be open if we do not fork, for monitoring for
  98          * close.  stdout must be open if we are logging there, and we
  99          * never close stderr (but debug might dup it onto a log file) */
 100         close_low_fds(do_fork, !log_stdout, false);
 101 }