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#if defined(LIBC_SCCS) && !defined(lint)
36static char sccsid[] = "@(#)wbuf.c	8.1 (Berkeley) 6/4/93";
37#endif /* LIBC_SCCS and not lint */
38#include <sys/cdefs.h>
39__FBSDID("$FreeBSD$");
40
41#include <errno.h>
42#include <stdio.h>
43#include "local.h"
44
45/*
46 * Write the given character into the (probably full) buffer for
47 * the given file.  Flush the buffer out if it is or becomes full,
48 * or if c=='\n' and the file is line buffered.
49 *
50 * Non-MT-safe
51 */
52int
53__swbuf(int c, FILE *fp)
54{
55	int n;
56
57	/*
58	 * In case we cannot write, or longjmp takes us out early,
59	 * make sure _w is 0 (if fully- or un-buffered) or -_bf._size
60	 * (if line buffered) so that we will get called again.
61	 * If we did not do this, a sufficient number of putc()
62	 * calls might wrap _w from negative to positive.
63	 */
64	fp->_w = fp->_lbfsize;
65	if (prepwrite(fp) != 0) {
66		errno = EBADF;
67		return (EOF);
68	}
69	c = (unsigned char)c;
70
71	ORIENT(fp, -1);
72
73	/*
74	 * If it is completely full, flush it out.  Then, in any case,
75	 * stuff c into the buffer.  If this causes the buffer to fill
76	 * completely, or if c is '\n' and the file is line buffered,
77	 * flush it (perhaps a second time).  The second flush will always
78	 * happen on unbuffered streams, where _bf._size==1; fflush()
79	 * guarantees that putc() will always call wbuf() by setting _w
80	 * to 0, so we need not do anything else.
81	 */
82	n = fp->_p - fp->_bf._base;
83	if (n >= fp->_bf._size) {
84		if (__fflush(fp))
85			return (EOF);
86		n = 0;
87	}
88	fp->_w--;
89	*fp->_p++ = c;
90	if (++n == fp->_bf._size || (fp->_flags & __SLBF && c == '\n'))
91		if (__fflush(fp))
92			return (EOF);
93	return (c);
94}
95