sysdeps/posix/fdopen.c

   1 /* Copyright (C) 1991, 1992, 1993 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
  16 not, write to the Free Software Foundation, Inc., 675 Mass Ave,
  17 Cambridge, MA 02139, USA.  */
  18
  19 #include <ansidecl.h>
  20 #include <errno.h>
  21 #include <stdio.h>
  22 #include <fcntl.h>
  23
  24 /* Defined in fopen.c.  */
  25 extern int EXFUN(__getmode, (CONST char *mode, __io_mode *mptr));
  26
  27 /* Open a new stream on a given system file descriptor.  */
  28 FILE *
  29 DEFUN(fdopen, (fd, mode), int fd AND CONST char *mode)
  30 {
  31   register FILE *stream;
  32   __io_mode m;
  33   int dflags;
  34
  35   if (!__getmode (mode, &m))
  36     return NULL;
  37
  38   /* Verify the FD is valid and allows the access MODE specifies.  */
  39
  40   dflags = __fcntl (fd, F_GETFL);
  41   if (dflags == -1)
  42     /* FD was invalid; fcntl has already set errno.  */
  43     return NULL;
  44
  45   /* Check the access mode.  */
  46   switch (dflags & O_ACCMODE)
  47     {
  48     case O_RDONLY:
  49       if (!m.__read)
  50         {
  51           errno = EBADF;
  52           return NULL;
  53         }
  54       break;
  55     case O_WRONLY:
  56       if (!m.__write)
  57         {
  58           errno = EBADF;
  59           return NULL;
  60         }
  61       break;
  62     }
  63
  64   stream = __newstream ();
  65   if (stream == NULL)
  66     return NULL;
  67
  68   stream->__cookie = (PTR) fd;
  69   stream->__mode = m;
  70
  71   return stream;
  72 }