1/*	$OpenBSD: wsetup.c,v 1.8 2023/10/06 16:41:02 millert Exp $ */
2/*-
3 * Copyright (c) 1990, 1993
4 *	The Regents of the University of California.  All rights reserved.
5 *
6 * This code is derived from software contributed to Berkeley by
7 * Chris Torek.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 *    notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 *    notice, this list of conditions and the following disclaimer in the
16 *    documentation and/or other materials provided with the distribution.
17 * 3. Neither the name of the University nor the names of its contributors
18 *    may be used to endorse or promote products derived from this software
19 *    without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34#include <errno.h>
35#include <stdio.h>
36#include <stdlib.h>
37#include "local.h"
38
39/*
40 * Various output routines call wsetup to be sure it is safe to write,
41 * because either _flags does not include __SWR, or _buf is NULL.
42 * __swsetup returns 0 if OK to write, nonzero otherwise, setting errno.
43 */
44int
45__swsetup(FILE *fp)
46{
47	/* make sure stdio is set up */
48	if (!__sdidinit)
49		__sinit();
50
51	/*
52	 * If we are not writing, we had better be reading and writing.
53	 */
54	if ((fp->_flags & __SWR) == 0) {
55		if ((fp->_flags & __SRW) == 0) {
56			errno = EBADF;
57			fp->_flags |= __SERR;
58			return (EOF);
59		}
60		if (fp->_flags & __SRD) {
61			/* clobber any ungetc data */
62			if (HASUB(fp))
63				FREEUB(fp);
64			fp->_flags &= ~(__SRD|__SEOF);
65			fp->_r = 0;
66			fp->_p = fp->_bf._base;
67		}
68		fp->_flags |= __SWR;
69	}
70
71	/*
72	 * Make a buffer if necessary, then set _w.
73	 */
74	if (fp->_bf._base == NULL) {
75		if ((fp->_flags & (__SSTR | __SALC)) == __SSTR) {
76			errno = EINVAL;
77			fp->_flags |= __SERR;
78			return (EOF);
79		}
80		__smakebuf(fp);
81	}
82	if (fp->_flags & __SLBF) {
83		/*
84		 * It is line buffered, so make _lbfsize be -_bufsize
85		 * for the putc() macro.  We will change _lbfsize back
86		 * to 0 whenever we turn off __SWR.
87		 */
88		fp->_w = 0;
89		fp->_lbfsize = -fp->_bf._size;
90	} else
91		fp->_w = fp->_flags & __SNBF ? 0 : fp->_bf._size;
92	return (0);
93}
94