1 /* $OpenBSD: memcpy.c,v 1.1 2014/11/30 19:43:56 deraadt 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 /* 48 * Copy a block of memory, not handling overlap. 49 */ 50 void * 51 memcpy(void *dst0, const void *src0, size_t length) 52 { 53 char *dst = dst0; 54 const char *src = src0; 55 size_t t; 56 57 if (length == 0 || dst == src) /* nothing to do */ 58 goto done; 59 60 if ((dst < src && dst + length > src) || 61 (src < dst && src + length > dst)) { 62 struct syslog_data sdata = SYSLOG_DATA_INIT; 63 64 syslog_r(LOG_CRIT, &sdata, "backwards memcpy"); 65 abort(); 66 } 67 68 /* 69 * Macros: loop-t-times; and loop-t-times, t>0 70 */ 71 #define TLOOP(s) if (t) TLOOP1(s) 72 #define TLOOP1(s) do { s; } while (--t) 73 74 /* 75 * Copy forward. 76 */ 77 t = (long)src; /* only need low bits */ 78 if ((t | (long)dst) & wmask) { 79 /* 80 * Try to align operands. This cannot be done 81 * unless the low bits match. 82 */ 83 if ((t ^ (long)dst) & wmask || length < wsize) 84 t = length; 85 else 86 t = wsize - (t & wmask); 87 length -= t; 88 TLOOP1(*dst++ = *src++); 89 } 90 /* 91 * Copy whole words, then mop up any trailing bytes. 92 */ 93 t = length / wsize; 94 TLOOP(*(word *)dst = *(word *)src; src += wsize; dst += wsize); 95 t = length & wmask; 96 TLOOP(*dst++ = *src++); 97 done: 98 return (dst0); 99 } 100