1 /* $NetBSD: fwrite.c,v 1.19 2021/02/01 17:50:53 jdolecek 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[] = "@(#)fwrite.c 8.1 (Berkeley) 6/4/93";
39 #else
40 __RCSID("$NetBSD: fwrite.c,v 1.19 2021/02/01 17:50:53 jdolecek 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 "reentrant.h"
48 #include "local.h"
49 #include "fvwrite.h"
50
51 #define MUL_NO_OVERFLOW (1UL << (sizeof(size_t) * 4))
52
53 /*
54 * Write `count' objects (each size `size') from memory to the given file.
55 * Return the number of whole objects written.
56 */
57 size_t
fwrite(const void * buf,size_t size,size_t count,FILE * fp)58 fwrite(const void *buf, size_t size, size_t count, FILE *fp)
59 {
60 size_t n;
61 struct __suio uio;
62 struct __siov iov;
63
64 /*
65 * Extension: Catch integer overflow
66 */
67 if ((size >= MUL_NO_OVERFLOW || count >= MUL_NO_OVERFLOW) &&
68 size > 0 && count > SIZE_MAX / size) {
69 errno = EOVERFLOW;
70 fp->_flags |= __SERR;
71 return (0);
72 }
73
74 /*
75 * SUSv2 requires a return value of 0 for a count or a size of 0.
76 */
77 if ((n = count * size) == 0)
78 return 0;
79
80 iov.iov_base = __UNCONST(buf);
81 uio.uio_resid = iov.iov_len = n;
82 uio.uio_iov = &iov;
83 uio.uio_iovcnt = 1;
84
85 /*
86 * The usual case is success (__sfvwrite returns 0);
87 * skip the divide if this happens, since divides are
88 * generally slow and since this occurs whenever size==0.
89 */
90 FLOCKFILE(fp);
91 if (__sfvwrite(fp, &uio) != 0)
92 count = ((n - uio.uio_resid) / size);
93 FUNLOCKFILE(fp);
94 return count;
95 }
96