lib/unlockpt.c

   1 /* Unlock the slave side of a pseudo-terminal from its master side.
   2    Copyright (C) 1998, 2010-2020 Free Software Foundation, Inc.
   3    Contributed by Zack Weinberg <zack@rabi.phys.columbia.edu>, 1998.
   4
   5    This program is free software: you can redistribute it and/or modify
   6    it under the terms of the GNU General Public License as published by
   7    the Free Software Foundation; either version 3 of the License, or
   8    (at your option) any later version.
   9
  10    This program 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
  13    GNU General Public License for more details.
  14
  15    You should have received a copy of the GNU General Public License
  16    along with this program.  If not, see <https://www.gnu.org/licenses/>.  */
  17
  18 #include <config.h>
  19
  20 #include <stdlib.h>
  21
  22 #include <fcntl.h>
  23 #include <unistd.h>
  24
  25 int
  26 unlockpt (int fd)
  27 {
  28   /* Platforms which have the TIOCSPTLCK ioctl (Linux) already have the
  29      unlockpt function.  */
  30 #if HAVE_REVOKE
  31   /* Mac OS X 10.3, OpenBSD 3.8 do not have the unlockpt function, but they
  32      have revoke().  */
  33   char *name = ptsname (fd);
  34   if (name == NULL)
  35     return -1;
  36   return revoke (name);
  37 #else
  38   /* Assume that the slave side of a pseudo-terminal is already unlocked
  39      by default.  */
  40   if (fcntl (fd, F_GETFD) < 0)
  41     return -1;
  42   return 0;
  43 #endif
  44 }