uclibc-ng/libc/stdlib/getpt.c

/* Copyright (C) 1998, 1999, 2001 Free Software Foundation, Inc.
   This file is part of the GNU C Library.
   Contributed by Zack Weinberg <zack@rabi.phys.columbia.edu>, 1998.

   The GNU C Library is free software; you can redistribute it and/or
   modify it under the terms of the GNU Lesser General Public
   License as published by the Free Software Foundation; either
   version 2.1 of the License, or (at your option) any later version.

   The GNU C Library is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
   Lesser General Public License for more details.

   You should have received a copy of the GNU Lesser General Public
   License along with the GNU C Library; if not, see
   <http://www.gnu.org/licenses/>.  */

#include <errno.h>
#include <fcntl.h>
#include <stdlib.h>
#include <stdbool.h>
#include <unistd.h>
#include <paths.h>
#include <sys/statfs.h>

extern __typeof(statfs) __libc_statfs;


#if !defined __ASSUME_DEVPTS__

/* Constant that identifies the `devpts' filesystem.  */
# define DEVPTS_SUPER_MAGIC	0x1cd1
/* Constant that identifies the `devfs' filesystem.  */
# define DEVFS_SUPER_MAGIC	0x1373
#endif

/* Path to the master pseudo terminal cloning device.  */
#define _PATH_DEVPTMX _PATH_DEV "ptmx"
/* Directory containing the UNIX98 pseudo terminals.  */
#define _PATH_DEVPTS _PATH_DEV "pts"

#if !defined __UNIX98PTY_ONLY__ && defined __UCLIBC_HAS_GETPT__
/* Prototype for function that opens BSD-style master pseudo-terminals.  */
static __inline__ int __bsd_getpt (void);
#endif

/* Open a master pseudo terminal and return its file descriptor.  */
static int
__posix_openpt (int flags)
{
#define have_no_dev_ptmx (1<<0)
#define devpts_mounted   (1<<1)
#if !defined __UNIX98PTY_ONLY__
  static smallint _state;
#endif
  int fd;

#if !defined __UNIX98PTY_ONLY__
  if (!(_state & have_no_dev_ptmx))
#endif
    {
      fd = open (_PATH_DEVPTMX, flags);
      if (fd != -1)
	{
#if defined __ASSUME_DEVPTS__
	  return fd;
#else
	  struct statfs fsbuf;

	  /* Check that the /dev/pts filesystem is mounted
	     or if /dev is a devfs filesystem (this implies /dev/pts).  */
	  if (
#if !defined __UNIX98PTY_ONLY__
	      (_state & devpts_mounted) ||
#endif
	      (__libc_statfs (_PATH_DEVPTS, &fsbuf) == 0
		  && fsbuf.f_type == DEVPTS_SUPER_MAGIC)
	      || (__libc_statfs (_PATH_DEV, &fsbuf) == 0
		  && fsbuf.f_type == DEVFS_SUPER_MAGIC))
	    {
	      /* Everything is ok.  */
#if !defined __UNIX98PTY_ONLY__
	      _state |= devpts_mounted;
#endif
	      return fd;
	    }

	  /* If /dev/pts is not mounted then the UNIX98 pseudo terminals
             are not usable.  */
	  close (fd);
#if !defined __UNIX98PTY_ONLY__
	  _state |= have_no_dev_ptmx;
#endif
#endif
	}
      else
	{
#if !defined __UNIX98PTY_ONLY__
	  if (errno == ENOENT || errno == ENODEV)
	    _state |= have_no_dev_ptmx;
	  else
#endif
	    return -1;
	}
    }
#if !defined __UNIX98PTY_ONLY__ && defined __UCLIBC_HAS_GETPT__
  /* If we have no ptmx then ignore flags and use the fallback.  */
  if (_state & have_no_dev_ptmx)
    return __bsd_getpt();
#endif
  return -1;
}
strong_alias(__posix_openpt,posix_openpt)
#undef have_no_dev_ptmx
#undef devpts_mounted

#if defined __USE_GNU && defined __UCLIBC_HAS_GETPT__
int getpt (void)
{
	return __posix_openpt(O_RDWR);
}

#if !defined __UNIX98PTY_ONLY__ && defined __UCLIBC_HAS_GETPT__
# define PTYNAME1 "pqrstuvwxyzabcde";
# define PTYNAME2 "0123456789abcdef";

# define __getpt __bsd_getpt
# include "bsd_getpt.c"
#endif
#endif /* GNU && __UCLIBC_HAS_GETPT__ */