fdopen.c

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/* Copyright (C) 1991, 1992, 1993 Free Software Foundation, Inc.
This file is part of the GNU C Library.

The GNU C Library is free software; you can redistribute it and/or
modify it under the terms of the GNU Library General Public License as
published by the Free Software Foundation; either version 2 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
Library General Public License for more details.

You should have received a copy of the GNU Library General Public
License along with the GNU C Library; see the file COPYING.LIB.  If
not, write to the Free Software Foundation, Inc., 675 Mass Ave,
Cambridge, MA 02139, USA.  */

#include <ansidecl.h>
#include <errno.h>
#include <stdio.h>
#include <fcntl.h>

/* Defined in fopen.c.  */
extern int EXFUN(__getmode, (CONST char *mode, __io_mode *mptr));

/* Open a new stream on a given system file descriptor.  */
FILE *
DEFUN(fdopen, (fd, mode), int fd AND CONST char *mode)
{
  register FILE *stream;
  __io_mode m;
  int dflags;

  if (!__getmode (mode, &m))
    return NULL;

  /* Verify the FD is valid and allows the access MODE specifies.  */

  dflags = __fcntl (fd, F_GETFL);
  if (dflags == -1)
    /* FD was invalid; fcntl has already set errno.  */
    return NULL;

  /* Check the access mode.  */
  switch (dflags & O_ACCMODE)
    {
    case O_RDONLY:
      if (!m.__read)
	{
	  errno = EBADF;
	  return NULL;
	}
      break;
    case O_WRONLY:
      if (!m.__write)
	{
	  errno = EBADF;
	  return NULL;
	}
      break;
    }

  stream = __newstream ();
  if (stream == NULL)
    return NULL;

  stream->__cookie = (PTR) fd;
  stream->__mode = m;

  return stream;
}