contrib/ldns/compat/memmove.c

   1 /*
   2  *      memmove.c: memmove compat implementation.
   3  *
   4  *      Copyright (c) 2001-2008, NLnet Labs. All rights reserved.
   5  *
   6  * See LICENSE for the license.
   7 */
   8
   9 #include <ldns/config.h>
  10 #include <stdlib.h>
  11
  12 void *memmove(void *dest, const void *src, size_t n);
  13
  14 void *memmove(void *dest, const void *src, size_t n)
  15 {
  16         uint8_t* from = (uint8_t*) src;
  17         uint8_t* to = (uint8_t*) dest;
  18
  19         if (from == to || n == 0)
  20                 return dest;
  21         if (to > from && to-from < (int)n) {
  22                 /* to overlaps with from */
  23                 /*  <from......>         */
  24                 /*         <to........>  */
  25                 /* copy in reverse, to avoid overwriting from */
  26                 int i;
  27                 for(i=n-1; i>=0; i--)
  28                         to[i] = from[i];
  29                 return dest;
  30         }
  31         if (from > to  && from-to < (int)n) {
  32                 /* to overlaps with from */
  33                 /*        <from......>   */
  34                 /*  <to........>         */
  35                 /* copy forwards, to avoid overwriting from */
  36                 size_t i;
  37                 for(i=0; i<n; i++)
  38                         to[i] = from[i];
  39                 return dest;
  40         }
  41         memcpy(dest, src, n);
  42         return dest;
  43 }