libc/stdlib/getpt.c

   1 /* Copyright (C) 1998, 1999, 2001 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 Lesser General Public
   7    License as published by the Free Software Foundation; either
   8    version 2.1 of the 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    Lesser General Public License for more details.
  14
  15    You should have received a copy of the GNU Lesser General Public
  16    License along with the GNU C Library; if not, see
  17    <http://www.gnu.org/licenses/>.  */
  18
  19 #include <errno.h>
  20 #include <fcntl.h>
  21 #include <stdlib.h>
  22 #include <stdbool.h>
  23 #include <unistd.h>
  24 #include <paths.h>
  25 #include <sys/statfs.h>
  26
  27 extern __typeof(statfs) __libc_statfs;
  28
  29
  30 #if !defined __ASSUME_DEVPTS__
  31
  32 /* Constant that identifies the `devpts' filesystem.  */
  33 # define DEVPTS_SUPER_MAGIC     0x1cd1
  34 /* Constant that identifies the `devfs' filesystem.  */
  35 # define DEVFS_SUPER_MAGIC      0x1373
  36 #endif
  37
  38 /* Path to the master pseudo terminal cloning device.  */
  39 #define _PATH_DEVPTMX _PATH_DEV "ptmx"
  40 /* Directory containing the UNIX98 pseudo terminals.  */
  41 #define _PATH_DEVPTS _PATH_DEV "pts"
  42
  43 #if !defined __UNIX98PTY_ONLY__ && defined __UCLIBC_HAS_GETPT__
  44 /* Prototype for function that opens BSD-style master pseudo-terminals.  */
  45 static __inline__ int __bsd_getpt (void);
  46 #endif
  47
  48 /* Open a master pseudo terminal and return its file descriptor.  */
  49 static int
  50 __posix_openpt (int flags)
  51 {
  52 #define have_no_dev_ptmx (1<<0)
  53 #define devpts_mounted   (1<<1)
  54 #if !defined __UNIX98PTY_ONLY__
  55   static smallint _state;
  56 #endif
  57   int fd;
  58
  59 #if !defined __UNIX98PTY_ONLY__
  60   if (!(_state & have_no_dev_ptmx))
  61 #endif
  62     {
  63       fd = open (_PATH_DEVPTMX, flags);
  64       if (fd != -1)
  65         {
  66 #if defined __ASSUME_DEVPTS__
  67           return fd;
  68 #else
  69           struct statfs fsbuf;
  70
  71           /* Check that the /dev/pts filesystem is mounted
  72              or if /dev is a devfs filesystem (this implies /dev/pts).  */
  73           if (
  74 #if !defined __UNIX98PTY_ONLY__
  75               (_state & devpts_mounted) ||
  76 #endif
  77               (__libc_statfs (_PATH_DEVPTS, &fsbuf) == 0
  78                   && fsbuf.f_type == DEVPTS_SUPER_MAGIC)
  79               || (__libc_statfs (_PATH_DEV, &fsbuf) == 0
  80                   && fsbuf.f_type == DEVFS_SUPER_MAGIC))
  81             {
  82               /* Everything is ok.  */
  83 #if !defined __UNIX98PTY_ONLY__
  84               _state |= devpts_mounted;
  85 #endif
  86               return fd;
  87             }
  88
  89           /* If /dev/pts is not mounted then the UNIX98 pseudo terminals
  90              are not usable.  */
  91           close (fd);
  92 #if !defined __UNIX98PTY_ONLY__
  93           _state |= have_no_dev_ptmx;
  94 #endif
  95 #endif
  96         }
  97       else
  98         {
  99 #if !defined __UNIX98PTY_ONLY__
 100           if (errno == ENOENT || errno == ENODEV)
 101             _state |= have_no_dev_ptmx;
 102           else
 103 #endif
 104             return -1;
 105         }
 106     }
 107 #if !defined __UNIX98PTY_ONLY__ && defined __UCLIBC_HAS_GETPT__
 108   /* If we have no ptmx then ignore flags and use the fallback.  */
 109   if (_state & have_no_dev_ptmx)
 110     return __bsd_getpt();
 111 #endif
 112   return -1;
 113 }
 114 strong_alias(__posix_openpt,posix_openpt)
 115 #undef have_no_dev_ptmx
 116 #undef devpts_mounted
 117
 118 #if defined __USE_GNU && defined __UCLIBC_HAS_GETPT__
 119 int getpt (void)
 120 {
 121         return __posix_openpt(O_RDWR);
 122 }
 123
 124 #if !defined __UNIX98PTY_ONLY__ && defined __UCLIBC_HAS_GETPT__
 125 # define PTYNAME1 "pqrstuvwxyzabcde";
 126 # define PTYNAME2 "0123456789abcdef";
 127
 128 # define __getpt __bsd_getpt
 129 # include "bsd_getpt.c"
 130 #endif
 131 #endif /* GNU && __UCLIBC_HAS_GETPT__ */