wbuf.c revision 1573 
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. All advertising materials mentioning features or use of this software
17 *    must display the following acknowledgement:
18 *	This product includes software developed by the University of
19 *	California, Berkeley and its contributors.
20 * 4. Neither the name of the University nor the names of its contributors
21 *    may be used to endorse or promote products derived from this software
22 *    without specific prior written permission.
23 *
24 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
25 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
26 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
27 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
28 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
29 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
30 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
31 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
32 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
33 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
34 * SUCH DAMAGE.
35 */
36
37#if defined(LIBC_SCCS) && !defined(lint)
38static char sccsid[] = "@(#)wbuf.c	8.1 (Berkeley) 6/4/93";
39#endif /* LIBC_SCCS and not lint */
40
41#include <stdio.h>
42#include "local.h"
43
44/*
45 * Write the given character into the (probably full) buffer for
46 * the given file.  Flush the buffer out if it is or becomes full,
47 * or if c=='\n' and the file is line buffered.
48 */
49__swbuf(c, fp)
50	register int c;
51	register FILE *fp;
52{
53	register int n;
54
55	/*
56	 * In case we cannot write, or longjmp takes us out early,
57	 * make sure _w is 0 (if fully- or un-buffered) or -_bf._size
58	 * (if line buffered) so that we will get called again.
59	 * If we did not do this, a sufficient number of putc()
60	 * calls might wrap _w from negative to positive.
61	 */
62	fp->_w = fp->_lbfsize;
63	if (cantwrite(fp))
64		return (EOF);
65	c = (unsigned char)c;
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))
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))
86			return (EOF);
87	return (c);
88}
89