libc/stdlib/unlockpt.c

   1 /* Copyright (C) 1998 Free Software Foundation, Inc.
   2    This file is part of the GNU C Library.
   3    Contributed by Zack Weinberg <zack@rabi.phys.columbia.edu>, 1998.
   4
   5    The GNU C Library is free software; you can redistribute it and/or
   6    modify it under the terms of the GNU Library General Public License as
   7    published by the Free Software Foundation; either version 2 of the
   8    License, or (at your option) any later version.
   9
  10    The GNU C Library is distributed in the hope that it will be useful,
  11    but WITHOUT ANY WARRANTY; without even the implied warranty of
  12    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13    Library General Public License for more details.
  14
  15    You should have received a copy of the GNU Library General Public
  16    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  17    see <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <stdlib.h>
  21 #include <sys/ioctl.h>
  22 #include <termios.h>
  23
  24
  25 /* Unlock the slave pseudo terminal associated with the master pseudo
  26    terminal specified by FD.  */
  27 int
  28 unlockpt (int fd)
  29 {
  30 #ifdef TIOCSPTLCK
  31   int save_errno = errno;
  32   int unlock = 0;
  33
  34   if (ioctl (fd, TIOCSPTLCK, &unlock))
  35     {
  36       if (errno == EINVAL)
  37         {
  38           errno = save_errno;
  39           return 0;
  40         }
  41       else
  42         return -1;
  43     }
  44 #endif
  45   /* If we have no TIOCSPTLCK ioctl, all slave pseudo terminals are
  46      unlocked by default.  */
  47   return 0;
  48 }