sysdeps/unix/bsd/setsid.c

   1 /* Copyright (C) 1991, 1995, 1996, 1997 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3
   4    The GNU C Library is free software; you can redistribute it and/or
   5    modify it under the terms of the GNU Lesser General Public
   6    License as published by the Free Software Foundation; either
   7    version 2.1 of the License, or (at your option) any later version.
   8
   9    The GNU C Library is distributed in the hope that it will be useful,
  10    but WITHOUT ANY WARRANTY; without even the implied warranty of
  11    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  12    Lesser General Public License for more details.
  13
  14    You should have received a copy of the GNU Lesser General Public
  15    License along with the GNU C Library; if not, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include <errno.h>
  20 #include <unistd.h>
  21 #include <sys/ioctl.h>
  22 #include <sys/types.h>
  23 #include <fcntl.h>
  24
  25 /* Create a new session with the calling process as its leader.
  26    The process group IDs of the session and the calling process
  27    are set to the process ID of the calling process, which is returned.  */
  28 int
  29 __setsid ()
  30 {
  31   pid_t pid = getpid ();
  32   int tty;
  33   int save = errno;
  34
  35   if (__getpgid (pid) == pid)
  36     {
  37       /* Already the leader.  */
  38       __set_errno (EPERM);
  39       return -1;
  40     }
  41
  42   if (setpgid (pid, pid) < 0)
  43     return -1;
  44
  45   tty = open ("/dev/tty", 0);
  46   if (tty < 0)
  47     {
  48       __set_errno (save);
  49       return 0;
  50     }
  51   (void) __ioctl (tty, TIOCNOTTY, 0);
  52   (void) __close (tty);
  53
  54   __set_errno (save);
  55   return 0;
  56 }
  57
  58 weak_alias (__setsid, setsid)