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 */
44 int
__swsetup(FILE * fp)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