glibc/stdio/newstream.c

/* Copyright (C) 1991, 1992, 1997 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., 59 Temple Place - Suite 330,
   Boston, MA 02111-1307, USA.  */

#include <stddef.h>
#include <stdio.h>
#include <stdlib.h>


/* Return a new, zeroed, stream.
   You must set its cookie and io_mode.
   The first operation will give it a buffer unless you do.
   It will also give it the default functions unless you set the `seen' flag.
   Returns NULL if a stream can't be created.  */
FILE *
__newstream (void)
{
  register FILE *stream;

  stream = __stdio_head;
  while (__validfp (stream))
    stream = stream->__next;
  if (stream == NULL)
    {
      /* None to reuse.  */
      stream = (FILE *) malloc (sizeof (FILE));
      if (stream == NULL)
	return NULL;
      stream->__next = __stdio_head;
      __stdio_head = stream;
    }

  __invalidate (stream);
  stream->__magic = _IOMAGIC;
  stream->__offset = (fpos_t) -1;
  stream->__target = (fpos_t) -1;

  return stream;
}