1 /* $NetBSD: setvbuf.c,v 1.19 2012/03/15 18:22:30 christos Exp $ */
2
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 <sys/cdefs.h>
36 #if defined(LIBC_SCCS) && !defined(lint)
37 #if 0
38 static char sccsid[] = "@(#)setvbuf.c 8.2 (Berkeley) 11/16/93";
39 #else
40 __RCSID("$NetBSD: setvbuf.c,v 1.19 2012/03/15 18:22:30 christos Exp $");
41 #endif
42 #endif /* LIBC_SCCS and not lint */
43
44 #include <assert.h>
45 #include <errno.h>
46 #include <stdio.h>
47 #include <stdlib.h>
48 #include <wchar.h>
49 #include "reentrant.h"
50 #include "local.h"
51
52 /*
53 * Set one of the three kinds of buffering, optionally including
54 * a buffer.
55 */
56 int
setvbuf(FILE * fp,char * buf,int mode,size_t size)57 setvbuf(FILE *fp, char *buf, int mode, size_t size)
58 {
59 int ret, flags;
60 size_t iosize;
61 int ttyflag;
62
63 _DIAGASSERT(fp != NULL);
64 /* buf may be NULL */
65
66 /*
67 * Verify arguments. The `int' limit on `size' is due to this
68 * particular implementation. Note, buf and size are ignored
69 * when setting _IONBF.
70 */
71 if (mode != _IONBF)
72 if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0)
73 return -1;
74
75 FLOCKFILE(fp);
76 /*
77 * Write current buffer, if any. Discard unread input (including
78 * ungetc data), cancel line buffering, and free old buffer if
79 * malloc()ed. We also clear any eof condition, as if this were
80 * a seek.
81 */
82 ret = 0;
83 (void)__sflush(fp);
84 if (HASUB(fp))
85 FREEUB(fp);
86 WCIO_FREE(fp);
87 fp->_r = fp->_lbfsize = 0;
88 flags = fp->_flags;
89 if (flags & __SMBF)
90 free((void *)fp->_bf._base);
91 flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SNPT | __SEOF);
92
93 /* If setting unbuffered mode, skip all the hard work. */
94 if (mode == _IONBF)
95 goto nbf;
96
97 /*
98 * Find optimal I/O size for seek optimization. This also returns
99 * a `tty flag' to suggest that we check isatty(fd), but we do not
100 * care since our caller told us how to buffer.
101 */
102 flags |= __swhatbuf(fp, &iosize, &ttyflag);
103 if (size == 0) {
104 buf = NULL; /* force local allocation */
105 size = iosize;
106 }
107
108 /* Allocate buffer if needed. */
109 if (buf == NULL) {
110 if ((buf = malloc(size)) == NULL) {
111 /*
112 * Unable to honor user's request. We will return
113 * failure, but try again with file system size.
114 */
115 ret = -1;
116 if (size != iosize) {
117 size = iosize;
118 buf = malloc(size);
119 }
120 }
121 if (buf == NULL) {
122 /* No luck; switch to unbuffered I/O. */
123 nbf:
124 fp->_flags = flags | __SNBF;
125 fp->_w = 0;
126 fp->_bf._base = fp->_p = fp->_nbuf;
127 fp->_bf._size = 1;
128 FUNLOCKFILE(fp);
129 return ret;
130 }
131 flags |= __SMBF;
132 }
133
134 /*
135 * Kill any seek optimization if the buffer is not the
136 * right size.
137 *
138 * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)?
139 */
140 if (size != iosize)
141 flags |= __SNPT;
142
143 /*
144 * Fix up the FILE fields, and set __cleanup for output flush on
145 * exit (since we are buffered in some way).
146 */
147 if (mode == _IOLBF)
148 flags |= __SLBF;
149 fp->_flags = flags;
150 fp->_bf._base = fp->_p = (unsigned char *)buf;
151 _DIAGASSERT(__type_fit(int, size));
152 fp->_bf._size = (int)size;
153 /* fp->_lbfsize is still 0 */
154 if (flags & __SWR) {
155 /*
156 * Begin or continue writing: see __swsetup(). Note
157 * that __SNBF is impossible (it was handled earlier).
158 */
159 if (flags & __SLBF) {
160 fp->_w = 0;
161 fp->_lbfsize = -fp->_bf._size;
162 } else {
163 _DIAGASSERT(__type_fit(int, size));
164 fp->_w = (int)size;
165 }
166 } else {
167 /* begin/continue reading, or stay in intermediate state */
168 fp->_w = 0;
169 }
170 __cleanup = _cleanup;
171
172 FUNLOCKFILE(fp);
173 return ret;
174 }
175