1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
|
/* $NetBSD: swab.c,v 1.20 2022/12/28 15:34:19 riastradh Exp $ */
/*-
* Copyright (c) 2022 The NetBSD Foundation, Inc.
* All rights reserved.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
*
* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
* POSSIBILITY OF SUCH DAMAGE.
*/
#include <sys/cdefs.h>
#if defined(LIBC_SCCS) && !defined(lint)
__RCSID("$NetBSD: swab.c,v 1.20 2022/12/28 15:34:19 riastradh Exp $");
#endif
#include <assert.h>
#include <unistd.h>
void
swab(const void *__restrict src, void *__restrict dst, ssize_t nbytes)
{
const char *p = src;
char *q = dst;
size_t n;
_DIAGASSERT(src != NULL);
_DIAGASSERT(dst != NULL);
if (nbytes <= 1)
return;
/*
* Round nbytes/2 down; we ignore the last byte altogether if
* nbytes is odd. This way, if the destination array is
* uninitialized, sanitizers will recognize the last byte as
* still uninitialized and flag it as undefined.
*/
for (n = nbytes/2; n --> 0; p += 2, q += 2) {
/*
* According to POSIX (2018), the behaviour is
* undefined if src and dst overlap. However, there
* are uses in-tree (xsrc/external/mit/xfwp/dist/io.c)
* that rely on swab(ptr, ptr, n) to do the swabbing
* in-place. So make sure this works if src == dst.
*/
const char p0 = p[0], p1 = p[1];
q[0] = p1;
q[1] = p0;
}
}
|