wsetup.c revision 331722 
1/*-
2 * Copyright (c) 1990, 1993
3 *	The Regents of the University of California.  All rights reserved.
4 *
5 * This code is derived from software contributed to Berkeley by
6 * Chris Torek.
7 *
8 * Redistribution and use in source and binary forms, with or without
9 * modification, are permitted provided that the following conditions
10 * are met:
11 * 1. Redistributions of source code must retain the above copyright
12 *    notice, this list of conditions and the following disclaimer.
13 * 2. Redistributions in binary form must reproduce the above copyright
14 *    notice, this list of conditions and the following disclaimer in the
15 *    documentation and/or other materials provided with the distribution.
16 * 3. Neither the name of the University nor the names of its contributors
17 *    may be used to endorse or promote products derived from this software
18 *    without specific prior written permission.
19 *
20 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
21 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
22 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
23 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
24 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
25 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
26 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
27 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
28 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
29 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
30 * SUCH DAMAGE.
31 */
32
33#if defined(LIBC_SCCS) && !defined(lint)
34static char sccsid[] = "@(#)wsetup.c	8.1 (Berkeley) 6/4/93";
35#endif /* LIBC_SCCS and not lint */
36#include <sys/cdefs.h>
37__FBSDID("$FreeBSD: stable/11/lib/libc/stdio/wsetup.c 331722 2018-03-29 02:50:57Z eadler $");
38
39#include <errno.h>
40#include <stdio.h>
41#include <stdlib.h>
42#include "local.h"
43
44/*
45 * Various output routines call wsetup to be sure it is safe to write,
46 * because either _flags does not include __SWR, or _buf is NULL.
47 * _wsetup returns 0 if OK to write; otherwise, it returns EOF and sets errno.
48 */
49int
50__swsetup(FILE *fp)
51{
52	/* make sure stdio is set up */
53	if (!__sdidinit)
54		__sinit();
55
56	/*
57	 * If we are not writing, we had better be reading and writing.
58	 */
59	if ((fp->_flags & __SWR) == 0) {
60		if ((fp->_flags & __SRW) == 0) {
61			errno = EBADF;
62			fp->_flags |= __SERR;
63			return (EOF);
64		}
65		if (fp->_flags & __SRD) {
66			/* clobber any ungetc data */
67			if (HASUB(fp))
68				FREEUB(fp);
69			fp->_flags &= ~(__SRD|__SEOF);
70			fp->_r = 0;
71			fp->_p = fp->_bf._base;
72		}
73		fp->_flags |= __SWR;
74	}
75
76	/*
77	 * Make a buffer if necessary, then set _w.
78	 */
79	if (fp->_bf._base == NULL)
80		__smakebuf(fp);
81	if (fp->_flags & __SLBF) {
82		/*
83		 * It is line buffered, so make _lbfsize be -_bufsize
84		 * for the putc() macro.  We will change _lbfsize back
85		 * to 0 whenever we turn off __SWR.
86		 */
87		fp->_w = 0;
88		fp->_lbfsize = -fp->_bf._size;
89	} else
90		fp->_w = fp->_flags & __SNBF ? 0 : fp->_bf._size;
91	return (0);
92}
93