lib/tcgetsid.c

   1 /* Determine the session ID of the controlling terminal of the current process.
   2    Copyright (C) 2010-2021 Free Software Foundation, Inc.
   3
   4    This program is free software; you can redistribute it and/or modify
   5    it under the terms of the GNU General Public License as published by
   6    the Free Software Foundation; either version 2, or (at your option)
   7    any later version.
   8
   9    This program 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
  12    GNU General Public License for more details.
  13
  14    You should have received a copy of the GNU General Public License
  15    along with this program; if not, see <https://www.gnu.org/licenses/>.  */
  16
  17 #include <config.h>
  18
  19 #define USE_OLD_TTY /* needed on OpenBSD 4.5, so that TIOCGSID gets defined */
  20
  21 /* Specification.  */
  22 #include <termios.h>
  23
  24 #include <errno.h>
  25 #include <sys/ioctl.h>
  26
  27 pid_t
  28 tcgetsid (int fd)
  29 {
  30 #ifdef TIOCGSID /* Mac OS X, OpenBSD */
  31   int sid;
  32
  33   if (ioctl (fd, TIOCGSID, &sid) < 0)
  34     return -1; /* errno is set here */
  35
  36   return sid;
  37 #else /* FreeBSD, Cygwin, mingw */
  38   errno = ENOSYS;
  39   return -1;
  40 #endif
  41 }