xref: /freebsd/lib/libc/stdio/wbuf.c (revision 8d20be1e22095c27faf8fe8b2f0d089739cc742e)
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)
34 static char sccsid[] = "@(#)wbuf.c	8.1 (Berkeley) 6/4/93";
35 #endif /* LIBC_SCCS and not lint */
36 #include <sys/cdefs.h>
37 __FBSDID("$FreeBSD$");
38 
39 #include <stdio.h>
40 #include "local.h"
41 
42 /*
43  * Write the given character into the (probably full) buffer for
44  * the given file.  Flush the buffer out if it is or becomes full,
45  * or if c=='\n' and the file is line buffered.
46  *
47  * Non-MT-safe
48  */
49 int
50 __swbuf(int c, FILE *fp)
51 {
52 	int n;
53 
54 	/*
55 	 * In case we cannot write, or longjmp takes us out early,
56 	 * make sure _w is 0 (if fully- or un-buffered) or -_bf._size
57 	 * (if line buffered) so that we will get called again.
58 	 * If we did not do this, a sufficient number of putc()
59 	 * calls might wrap _w from negative to positive.
60 	 */
61 	fp->_w = fp->_lbfsize;
62 	if (prepwrite(fp) != 0)
63 		return (EOF);
64 	c = (unsigned char)c;
65 
66 	ORIENT(fp, -1);
67 
68 	/*
69 	 * If it is completely full, flush it out.  Then, in any case,
70 	 * stuff c into the buffer.  If this causes the buffer to fill
71 	 * completely, or if c is '\n' and the file is line buffered,
72 	 * flush it (perhaps a second time).  The second flush will always
73 	 * happen on unbuffered streams, where _bf._size==1; fflush()
74 	 * guarantees that putc() will always call wbuf() by setting _w
75 	 * to 0, so we need not do anything else.
76 	 */
77 	n = fp->_p - fp->_bf._base;
78 	if (n >= fp->_bf._size) {
79 		if (__fflush(fp))
80 			return (EOF);
81 		n = 0;
82 	}
83 	fp->_w--;
84 	*fp->_p++ = c;
85 	if (++n == fp->_bf._size || (fp->_flags & __SLBF && c == '\n'))
86 		if (__fflush(fp))
87 			return (EOF);
88 	return (c);
89 }
90