lib/libc/stdio/wsetup.c

   1 /*      $NetBSD: wsetup.c,v 1.12 2012/03/15 18:22:31 christos Exp $     */
   2
   3 /*-
   4  * Copyright (c) 1990, 1993
   5  *      The Regents of the University of California.  All rights reserved.
   6  *
   7  * This code is derived from software contributed to Berkeley by
   8  * Chris Torek.
   9  *
  10  * Redistribution and use in source and binary forms, with or without
  11  * modification, are permitted provided that the following conditions
  12  * are met:
  13  * 1. Redistributions of source code must retain the above copyright
  14  *    notice, this list of conditions and the following disclaimer.
  15  * 2. Redistributions in binary form must reproduce the above copyright
  16  *    notice, this list of conditions and the following disclaimer in the
  17  *    documentation and/or other materials provided with the distribution.
  18  * 3. Neither the name of the University nor the names of its contributors
  19  *    may be used to endorse or promote products derived from this software
  20  *    without specific prior written permission.
  21  *
  22  * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
  23  * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
  24  * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
  25  * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
  26  * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
  27  * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
  28  * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
  29  * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
  30  * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
  31  * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
  32  * SUCH DAMAGE.
  33  */
  34
  35 #include <sys/cdefs.h>
  36 #if defined(LIBC_SCCS) && !defined(lint)
  37 #if 0
  38 static char sccsid[] = "@(#)wsetup.c    8.1 (Berkeley) 6/4/93";
  39 #else
  40 __RCSID("$NetBSD: wsetup.c,v 1.12 2012/03/15 18:22:31 christos Exp $");
  41 #endif
  42 #endif /* LIBC_SCCS and not lint */
  43
  44 #include <assert.h>
  45 #include <errno.h>
  46 #include <stdio.h>
  47 #include <stdlib.h>
  48 #include "reentrant.h"
  49 #include "local.h"
  50
  51 /*
  52  * Various output routines call wsetup to be sure it is safe to write,
  53  * because either _flags does not include __SWR, or _buf is NULL.
  54  * _wsetup returns 0 if OK to write, nonzero otherwise.
  55  */
  56 int
  57 __swsetup(FILE *fp)
  58 {
  59
  60         _DIAGASSERT(fp != NULL);
  61
  62         /* make sure stdio is set up */
  63         if (!__sdidinit)
  64                 __sinit();
  65
  66         /*
  67          * If we are not writing, we had better be reading and writing.
  68          */
  69         if ((fp->_flags & __SWR) == 0) {
  70                 if ((fp->_flags & __SRW) == 0)
  71                         return EOF;
  72                 if (fp->_flags & __SRD) {
  73                         /* clobber any ungetc data */
  74                         if (HASUB(fp))
  75                                 FREEUB(fp);
  76                         fp->_flags &= ~(__SRD|__SEOF);
  77                         fp->_r = 0;
  78                         fp->_p = fp->_bf._base;
  79                 }
  80                 fp->_flags |= __SWR;
  81         }
  82
  83         /*
  84          * Make a buffer if necessary, then set _w.
  85          */
  86         if (fp->_bf._base == NULL)
  87                 __smakebuf(fp);
  88         if (fp->_flags & __SLBF) {
  89                 /*
  90                  * It is line buffered, so make _lbfsize be -_bufsize
  91                  * for the putc() macro.  We will change _lbfsize back
  92                  * to 0 whenever we turn off __SWR.
  93                  */
  94                 fp->_w = 0;
  95                 fp->_lbfsize = -fp->_bf._size;
  96         } else
  97                 fp->_w = fp->_flags & __SNBF ? 0 : fp->_bf._size;
  98         return 0;
  99 }