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 * @(#)setvbuf.c 8.2 (Berkeley) 11/16/93
33 * $FreeBSD: src/lib/libc/stdio/setvbuf.c,v 1.14 2007/01/09 00:28:07 imp Exp $
34 */
35
36 #include "namespace.h"
37 #include <stdio.h>
38 #include <stdlib.h>
39 #include "un-namespace.h"
40 #include "local.h"
41 #include "libc_private.h"
42
43 /*
44 * Set one of the three kinds of buffering, optionally including
45 * a buffer.
46 */
47 int
setvbuf(FILE * __restrict fp,char * __restrict buf,int mode,size_t size)48 setvbuf(FILE * __restrict fp, char * __restrict buf, int mode, size_t size)
49 {
50 int ret, flags;
51 size_t iosize;
52 int ttyflag;
53
54 /*
55 * Verify arguments. The `int' limit on `size' is due to this
56 * particular implementation. Note, buf and size are ignored
57 * when setting _IONBF.
58 */
59 if (mode != _IONBF)
60 if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0)
61 return (EOF);
62
63 FLOCKFILE(fp);
64 /*
65 * Write current buffer, if any. Discard unread input (including
66 * ungetc data), cancel line buffering, and free old buffer if
67 * malloc()ed. We also clear any eof condition, as if this were
68 * a seek.
69 */
70 ret = 0;
71 __sflush(fp);
72 if (HASUB(fp))
73 FREEUB(fp);
74 fp->pub._r = fp->pub._lbfsize = 0;
75 flags = fp->pub._flags;
76 if (flags & __SMBF)
77 free((void *)fp->_bf._base);
78 flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SOFF | __SNPT | __SEOF);
79
80 /* If setting unbuffered mode, skip all the hard work. */
81 if (mode == _IONBF)
82 goto nbf;
83
84 /*
85 * Find optimal I/O size for seek optimization. This also returns
86 * a `tty flag' to suggest that we check isatty(fd), but we do not
87 * care since our caller told us how to buffer.
88 */
89 flags |= __swhatbuf(fp, &iosize, &ttyflag);
90 if (size == 0) {
91 buf = NULL; /* force local allocation */
92 size = iosize;
93 }
94
95 /* Allocate buffer if needed. */
96 if (buf == NULL) {
97 if ((buf = malloc(size)) == NULL) {
98 /*
99 * Unable to honor user's request. We will return
100 * failure, but try again with file system size.
101 */
102 ret = EOF;
103 if (size != iosize) {
104 size = iosize;
105 buf = malloc(size);
106 }
107 }
108 if (buf == NULL) {
109 /* No luck; switch to unbuffered I/O. */
110 nbf:
111 fp->pub._flags = flags | __SNBF;
112 fp->pub._w = 0;
113 fp->_bf._base = fp->pub._p = fp->_nbuf;
114 fp->_bf._size = 1;
115 FUNLOCKFILE(fp);
116 return (ret);
117 }
118 flags |= __SMBF;
119 }
120
121 /*
122 * Kill any seek optimization if the buffer is not the
123 * right size.
124 *
125 * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)?
126 */
127 if (size != iosize)
128 flags |= __SNPT;
129
130 /*
131 * Fix up the FILE fields, and set __cleanup for output flush on
132 * exit (since we are buffered in some way).
133 */
134 if (mode == _IOLBF)
135 flags |= __SLBF;
136 fp->pub._flags = flags;
137 fp->_bf._base = fp->pub._p = (unsigned char *)buf;
138 fp->_bf._size = size;
139 /* fp->_lbfsize is still 0 */
140 if (flags & __SWR) {
141 /*
142 * Begin or continue writing: see __swsetup(). Note
143 * that __SNBF is impossible (it was handled earlier).
144 */
145 if (flags & __SLBF) {
146 fp->pub._w = 0;
147 fp->pub._lbfsize = -fp->_bf._size;
148 } else
149 fp->pub._w = size;
150 } else {
151 /* begin/continue reading, or stay in intermediate state */
152 fp->pub._w = 0;
153 }
154 __cleanup = _cleanup;
155
156 FUNLOCKFILE(fp);
157 return (ret);
158 }
159