stdio/newstream.c

   1 /* Copyright (C) 1991, 1992, 1997 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 <stddef.h>
  20 #include <stdio.h>
  21 #include <stdlib.h>
  22
  23
  24 /* Return a new, zeroed, stream.
  25    You must set its cookie and io_mode.
  26    The first operation will give it a buffer unless you do.
  27    It will also give it the default functions unless you set the `seen' flag.
  28    Returns NULL if a stream can't be created.  */
  29 FILE *
  30 __newstream (void)
  31 {
  32   register FILE *stream;
  33
  34   stream = __stdio_head;
  35   while (__validfp (stream))
  36     stream = stream->__next;
  37   if (stream == NULL)
  38     {
  39       /* None to reuse.  */
  40       stream = (FILE *) malloc (sizeof (FILE));
  41       if (stream == NULL)
  42         return NULL;
  43       stream->__next = __stdio_head;
  44       __stdio_head = stream;
  45     }
  46
  47   __invalidate (stream);
  48   stream->__magic = _IOMAGIC;
  49   stream->__offset = (fpos_t) -1;
  50   stream->__target = (fpos_t) -1;
  51
  52   return stream;
  53 }