sysdeps/unix/sysv/linux/grantpt.c

   1 /* Copyright (C) 1998, 1999, 2001, 2002 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, write to the Free
  16    Software Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA
  17    02111-1307 USA.  */
  18
  19 #include <errno.h>
  20 #include <fcntl.h>
  21 #include <limits.h>
  22 #include <stdlib.h>
  23 #include <sys/statfs.h>
  24
  25 #include "linux_fsinfo.h"
  26
  27 /* Prototype for function that changes ownership and access permission
  28    for slave pseudo terminals that do not live on a `devpts'
  29    filesystem.  */
  30 static int __unix_grantpt (int fd);
  31
  32 /* Prototype for private function that gets the name of the slave
  33    pseudo terminal in a safe way.  */
  34 static int pts_name (int fd, char **pts, size_t buf_len);
  35
  36 /* Change the ownership and access permission of the slave pseudo
  37    terminal associated with the master pseudo terminal specified
  38    by FD.  */
  39 int
  40 grantpt (int fd)
  41 {
  42   struct statfs fsbuf;
  43 #ifdef PATH_MAX
  44   char _buf[PATH_MAX];
  45 #else
  46   char _buf[512];
  47 #endif
  48   char *buf = _buf;
  49
  50   if (__builtin_expect (pts_name (fd, &buf, sizeof (_buf)), 0))
  51     {
  52       int save_errno = errno;
  53
  54       /* Check, if the file descriptor is valid. pts_name returns the
  55          wrong errno number, so we cannot use that.  */
  56       if (__libc_fcntl (fd, F_GETFD) == -1 && errno == EBADF)
  57         return -1;
  58
  59        /* If the filedescriptor is no TTY, grantpt has to set errno
  60           to EINVAL.  */
  61        if (save_errno == ENOTTY)
  62          __set_errno (EINVAL);
  63        else
  64          __set_errno (save_errno);
  65
  66        return -1;
  67     }
  68
  69   if (__statfs (buf, &fsbuf) < 0)
  70     return -1;
  71
  72   /* If the slave pseudo terminal lives on a `devpts' filesystem, the
  73      ownership and access permission are already set.  */
  74   if (fsbuf.f_type == DEVPTS_SUPER_MAGIC || fsbuf.f_type == DEVFS_SUPER_MAGIC)
  75     return 0;
  76
  77   return __unix_grantpt (fd);
  78 }
  79
  80 #define grantpt static __unix_grantpt
  81 #include <sysdeps/unix/grantpt.c>