1 /* $OpenBSD: fwrite.c,v 1.11 2014/05/01 16:40:36 deraadt 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 <stdlib.h>
36 #include <stdint.h>
37 #include <errno.h>
38 #include "local.h"
39 #include "fvwrite.h"
40
41 #define MUL_NO_OVERFLOW (1UL << (sizeof(size_t) * 4))
42
43 /*
44 * Write `count' objects (each size `size') from memory to the given file.
45 * Return the number of whole objects written.
46 */
47 size_t
fwrite(const void * buf,size_t size,size_t count,FILE * fp)48 fwrite(const void *buf, size_t size, size_t count, FILE *fp)
49 {
50 size_t n;
51 struct __suio uio;
52 struct __siov iov;
53 int ret;
54
55 /*
56 * Extension: Catch integer overflow
57 */
58 if ((size >= MUL_NO_OVERFLOW || count >= MUL_NO_OVERFLOW) &&
59 size > 0 && SIZE_MAX / size < count) {
60 errno = EOVERFLOW;
61 fp->_flags |= __SERR;
62 return (0);
63 }
64
65 /*
66 * ANSI and SUSv2 require a return value of 0 if size or count are 0.
67 */
68 if ((n = count * size) == 0)
69 return (0);
70
71 iov.iov_base = (void *)buf;
72 uio.uio_resid = iov.iov_len = n;
73 uio.uio_iov = &iov;
74 uio.uio_iovcnt = 1;
75
76 /*
77 * The usual case is success (__sfvwrite returns 0);
78 * skip the divide if this happens, since divides are
79 * generally slow and since this occurs whenever size==0.
80 */
81 FLOCKFILE(fp);
82 _SET_ORIENTATION(fp, -1);
83 ret = __sfvwrite(fp, &uio);
84 FUNLOCKFILE(fp);
85 if (ret == 0)
86 return (count);
87 return ((n - uio.uio_resid) / size);
88 }
89