1 /* $OpenBSD: memcpy.c,v 1.4 2017/11/29 05:13:57 guenther Exp $ */
2 /*-
3 * Copyright (c) 1990 The Regents of the University of California.
4 * 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 <string.h>
35 #include <stdlib.h>
36 #include <syslog.h>
37
38 /*
39 * sizeof(word) MUST BE A POWER OF TWO
40 * SO THAT wmask BELOW IS ALL ONES
41 */
42 typedef long word; /* "word" used for optimal copy speed */
43
44 #define wsize sizeof(word)
45 #define wmask (wsize - 1)
46
47 static const char backwards_msg[] = ": backwards memcpy";
48
49 /*
50 * Copy a block of memory, not handling overlap.
51 */
52 void *
memcpy(void * dst0,const void * src0,size_t length)53 memcpy(void *dst0, const void *src0, size_t length)
54 {
55 char *dst = dst0;
56 const char *src = src0;
57 size_t t;
58
59 if (length == 0 || dst == src) /* nothing to do */
60 goto done;
61
62 if ((dst < src && dst + length > src) ||
63 (src < dst && src + length > dst)) {
64 char buf[1024];
65
66 /* <10> is LOG_CRIT */
67 strlcpy(buf, "<10>", sizeof buf);
68
69 /* Make sure progname does not fill the whole buffer */
70 strlcat(buf, __progname, sizeof(buf) - sizeof backwards_msg);
71 strlcat(buf, backwards_msg, sizeof buf);
72
73 sendsyslog(buf, strlen(buf), LOG_CONS);
74 abort();
75 }
76
77 /*
78 * Macros: loop-t-times; and loop-t-times, t>0
79 */
80 #define TLOOP(s) if (t) TLOOP1(s)
81 #define TLOOP1(s) do { s; } while (--t)
82
83 /*
84 * Copy forward.
85 */
86 t = (long)src; /* only need low bits */
87 if ((t | (long)dst) & wmask) {
88 /*
89 * Try to align operands. This cannot be done
90 * unless the low bits match.
91 */
92 if ((t ^ (long)dst) & wmask || length < wsize)
93 t = length;
94 else
95 t = wsize - (t & wmask);
96 length -= t;
97 TLOOP1(*dst++ = *src++);
98 }
99 /*
100 * Copy whole words, then mop up any trailing bytes.
101 */
102 t = length / wsize;
103 TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize);
104 t = length & wmask;
105 TLOOP(*dst++ = *src++);
106 done:
107 return (dst0);
108 }
109 DEF_BUILTIN(memcpy);
110