1 /*-
2 * Copyright (c) 1990 The Regents of the University of California.
3 * 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)
38 static char sccsid[] = "@(#)setvbuf.c 5.5 (Berkeley) 5/6/93";
39 #endif /* LIBC_SCCS and not lint */
40
41 #include <stdio.h>
42 #include <stdlib.h>
43 #include "local.h"
44
45 /*
46 * Set one of the three kinds of buffering, optionally including
47 * a buffer.
48 */
setvbuf(fp,buf,mode,size)49 setvbuf(fp, buf, mode, size)
50 register FILE *fp;
51 char *buf;
52 register int mode;
53 register size_t size;
54 {
55 register int ret, flags;
56 size_t iosize;
57 int ttyflag;
58
59 /*
60 * Verify arguments. The `int' limit on `size' is due to this
61 * particular implementation. Note, buf and size are ignored
62 * when setting _IONBF.
63 */
64 if (mode != _IONBF)
65 if ((mode != _IOFBF && mode != _IOLBF) || (int)size < 0)
66 return (EOF);
67
68 /*
69 * Write current buffer, if any. Discard unread input, cancel
70 * line buffering, and free old buffer if malloc()ed.
71 */
72 ret = 0;
73 (void)__sflush(fp);
74 fp->_r = fp->_lbfsize = 0;
75 flags = fp->_flags;
76 if (flags & __SMBF)
77 free((void *)fp->_bf._base);
78 flags &= ~(__SLBF | __SNBF | __SMBF | __SOPT | __SNPT);
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->_flags = flags | __SNBF;
112 fp->_w = 0;
113 fp->_bf._base = fp->_p = fp->_nbuf;
114 fp->_bf._size = 1;
115 return (ret);
116 }
117 flags |= __SMBF;
118 }
119
120 /*
121 * Kill any seek optimization if the buffer is not the
122 * right size.
123 *
124 * SHOULD WE ALLOW MULTIPLES HERE (i.e., ok iff (size % iosize) == 0)?
125 */
126 if (size != iosize)
127 flags |= __SNPT;
128
129 /*
130 * Fix up the FILE fields, and set __cleanup for output flush on
131 * exit (since we are buffered in some way). If in r/w mode, go
132 * to the intermediate state, so that everyone has to call
133 * __srefill or __swsetup on the first operation -- it is more
134 * trouble than it is worth to set things up correctly here.
135 */
136 if (mode == _IOLBF)
137 flags |= __SLBF;
138 if (flags & __SRW)
139 flags &= ~(__SRD | __SWR);
140 fp->_w = 0;
141 fp->_flags = flags;
142 fp->_bf._base = fp->_p = (unsigned char *)buf;
143 fp->_bf._size = size;
144 fp->_lbfsize = 0;
145 __cleanup = _cleanup;
146
147 return (ret);
148 }
149