sysdeps/unix/sysv/linux/getpt.c

   1 /* Copyright (C) 1998, 1999 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    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  18    Boston, MA 02111-1307, USA.  */
  19
  20 #include <errno.h>
  21 #include <fcntl.h>
  22 #include <stdlib.h>
  23 #include <unistd.h>
  24 #include <paths.h>
  25 #include <sys/statfs.h>
  26
  27 #include "linux_fsinfo.h"
  28
  29 /* Path to the master pseudo terminal cloning device.  */
  30 #define _PATH_DEVPTMX _PATH_DEV "ptmx"
  31 /* Directory containing the UNIX98 pseudo terminals.  */
  32 #define _PATH_DEVPTS _PATH_DEV "pts"
  33
  34 /* Prototype for function that opens BSD-style master pseudo-terminals.  */
  35 int __bsd_getpt (void);
  36
  37 /* Open a master pseudo terminal and return its file descriptor.  */
  38 int
  39 __getpt (void)
  40 {
  41   static int have_no_dev_ptmx;
  42   int fd;
  43
  44   if (!have_no_dev_ptmx)
  45     {
  46       fd = __open (_PATH_DEVPTMX, O_RDWR);
  47       if (fd != -1)
  48         {
  49           struct statfs fsbuf;
  50           static int devpts_mounted;
  51
  52           /* Check that the /dev/pts filesystem is mounted
  53              or if /dev is a devfs filesystem (this implies /dev/pts).  */
  54           if (devpts_mounted
  55               || (__statfs (_PATH_DEVPTS, &fsbuf) == 0
  56                   && fsbuf.f_type == DEVPTS_SUPER_MAGIC)
  57               || (__statfs (_PATH_DEV, &fsbuf) == 0
  58                   && fsbuf.f_type == DEVFS_SUPER_MAGIC))
  59             {
  60               /* Everything is ok.  */
  61               devpts_mounted = 1;
  62               return fd;
  63             }
  64
  65           /* If /dev/pts is not mounted then the UNIX98 pseudo terminals
  66              are not usable.  */
  67           __close (fd);
  68           have_no_dev_ptmx = 1;
  69         }
  70       else
  71         {
  72           if (errno == ENOENT || errno == ENODEV)
  73             have_no_dev_ptmx = 1;
  74           else
  75             return -1;
  76         }
  77     }
  78
  79   return __bsd_getpt ();
  80 }
  81
  82 #define PTYNAME1 "pqrstuvwxyzabcde";
  83 #define PTYNAME2 "0123456789abcdef";
  84
  85 #define __getpt __bsd_getpt
  86 #include <sysdeps/unix/bsd/getpt.c>