1/*-
2 * SPDX-License-Identifier: BSD-3-Clause
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 <errno.h>
36#include <stdio.h>
37#include <stdlib.h>
38#include "local.h"
39
40/*
41 * Various output routines call wsetup to be sure it is safe to write,
42 * because either _flags does not include __SWR, or _buf is NULL.
43 * _wsetup returns 0 if OK to write; otherwise, it returns EOF and sets errno.
44 */
45int
46__swsetup(FILE *fp)
47{
48	/* make sure stdio is set up */
49	if (!__sdidinit)
50		__sinit();
51
52	/*
53	 * If we are not writing, we had better be reading and writing.
54	 */
55	if ((fp->_flags & __SWR) == 0) {
56		if ((fp->_flags & __SRW) == 0) {
57			errno = EBADF;
58			fp->_flags |= __SERR;
59			return (EOF);
60		}
61		if (fp->_flags & __SRD) {
62			/* clobber any ungetc data */
63			if (HASUB(fp))
64				FREEUB(fp);
65			fp->_flags &= ~(__SRD|__SEOF);
66			fp->_r = 0;
67			fp->_p = fp->_bf._base;
68		}
69		fp->_flags |= __SWR;
70	}
71
72	/*
73	 * Make a buffer if necessary, then set _w.
74	 */
75	if (fp->_bf._base == NULL)
76		__smakebuf(fp);
77	if (fp->_flags & __SLBF) {
78		/*
79		 * It is line buffered, so make _lbfsize be -_bufsize
80		 * for the putc() macro.  We will change _lbfsize back
81		 * to 0 whenever we turn off __SWR.
82		 */
83		fp->_w = 0;
84		fp->_lbfsize = -fp->_bf._size;
85	} else
86		fp->_w = fp->_flags & __SNBF ? 0 : fp->_bf._size;
87	return (0);
88}
89