1  /* Copyright (C) 1998-2023 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, see
      16     <https://www.gnu.org/licenses/>.  */
      17  
      18  #include <errno.h>
      19  #include <stdlib.h>
      20  #include <sys/ioctl.h>
      21  #include <termios.h>
      22  
      23  
      24  /* Unlock the slave pseudo terminal associated with the master pseudo
      25     terminal specified by FD.  */
      26  int
      27  unlockpt (int fd)
      28  {
      29    int unlock = 0;
      30  
      31    int ret = __ioctl (fd, TIOCSPTLCK, &unlock);
      32    if (ret != 0 && errno == ENOTTY)
      33      /* POSIX mandates EINVAL for non-ptmx descriptors.  */
      34      __set_errno (EINVAL);
      35    return ret;
      36  }
      37  libc_hidden_def (unlockpt)