sysdeps/posix/fdopen.c

   1 /* Copyright (C) 1991, 1992, 1993, 1996 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 Library General Public License as
   6    published by the Free Software Foundation; either version 2 of the
   7    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    Library General Public License for more details.
  13
  14    You should have received a copy of the GNU Library General Public
  15    License along with the GNU C Library; see the file COPYING.LIB.  If not,
  16    write to the Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  17    Boston, MA 02111-1307, USA.  */
  18
  19 #include <errno.h>
  20 #include <stdio.h>
  21 #include <fcntl.h>
  22
  23 /* Defined in fopen.c.  */
  24 extern int __getmode (const char *mode, __io_mode *mptr);
  25
  26 /* Open a new stream on a given system file descriptor.  */
  27 FILE *
  28 fdopen (fd, mode)
  29      int fd;
  30      const char *mode;
  31 {
  32   register FILE *stream;
  33   __io_mode m;
  34   int dflags;
  35
  36   if (!__getmode (mode, &m))
  37     return NULL;
  38
  39   /* Verify the FD is valid and allows the access MODE specifies.  */
  40
  41   dflags = __fcntl (fd, F_GETFL);
  42   if (dflags == -1)
  43     /* FD was invalid; fcntl has already set errno.  */
  44     return NULL;
  45
  46   /* Check the access mode.  */
  47   switch (dflags & O_ACCMODE)
  48     {
  49     case O_RDONLY:
  50       if (!m.__read)
  51         {
  52           __set_errno (EBADF);
  53           return NULL;
  54         }
  55       break;
  56     case O_WRONLY:
  57       if (!m.__write)
  58         {
  59           __set_errno (EBADF);
  60           return NULL;
  61         }
  62       break;
  63     }
  64
  65   stream = __newstream ();
  66   if (stream == NULL)
  67     return NULL;
  68
  69   stream->__cookie = (void *) fd;
  70   stream->__mode = m;
  71
  72   return stream;
  73 }