1 /* $OpenBSD: wbuf.c,v 1.12 2009/11/09 00:18:28 kurt Exp $ */
2 /*-
3 * Copyright (c) 1990, 1993
4 * The Regents of the University of California. All rights reserved.
5 *
6 * This code is derived from software contributed to Berkeley by
7 * Chris Torek.
8 *
9 * Redistribution and use in source and binary forms, with or without
10 * modification, are permitted provided that the following conditions
11 * are met:
12 * 1. Redistributions of source code must retain the above copyright
13 * notice, this list of conditions and the following disclaimer.
14 * 2. Redistributions in binary form must reproduce the above copyright
15 * notice, this list of conditions and the following disclaimer in the
16 * documentation and/or other materials provided with the distribution.
17 * 3. Neither the name of the University nor the names of its contributors
18 * may be used to endorse or promote products derived from this software
19 * without specific prior written permission.
20 *
21 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
22 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
23 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
24 * ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
25 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
26 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
27 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
28 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
29 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
30 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
31 * SUCH DAMAGE.
32 */
33
34 #include <stdio.h>
35 #include <errno.h>
36 #include "local.h"
37
38 /*
39 * Write the given character into the (probably full) buffer for
40 * the given file. Flush the buffer out if it is or becomes full,
41 * or if c=='\n' and the file is line buffered.
42 */
43 int
__swbuf(int c,FILE * fp)44 __swbuf(int c, FILE *fp)
45 {
46 int n;
47
48 _SET_ORIENTATION(fp, -1);
49 /*
50 * In case we cannot write, or longjmp takes us out early,
51 * make sure _w is 0 (if fully- or un-buffered) or -_bf._size
52 * (if line buffered) so that we will get called again.
53 * If we did not do this, a sufficient number of putc()
54 * calls might wrap _w from negative to positive.
55 */
56 fp->_w = fp->_lbfsize;
57 if (cantwrite(fp)) {
58 errno = EBADF;
59 return (EOF);
60 }
61 c = (unsigned char)c;
62
63 /*
64 * If it is completely full, flush it out. Then, in any case,
65 * stuff c into the buffer. If this causes the buffer to fill
66 * completely, or if c is '\n' and the file is line buffered,
67 * flush it (perhaps a second time). The second flush will always
68 * happen on unbuffered streams, where _bf._size==1; __sflush()
69 * guarantees that putc() will always call wbuf() by setting _w
70 * to 0, so we need not do anything else.
71 */
72 n = fp->_p - fp->_bf._base;
73 if (n >= fp->_bf._size) {
74 if (__sflush(fp))
75 return (EOF);
76 n = 0;
77 }
78 fp->_w--;
79 *fp->_p++ = c;
80 if (++n == fp->_bf._size || (fp->_flags & __SLBF && c == '\n'))
81 if (__sflush(fp))
82 return (EOF);
83 return (c);
84 }
85