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