str_cpy function for "5 minute challege" by hola.org Requirements: http://thecodeil.com/

hola.c

char* str_cpy(char** dest, const char* source)
{
    unsigned int dest_size = *dest ? strlen(*dest) : 0;
    unsigned int source_size = strlen(source) + 1;

    /* check if source is a part of dest - no need to reallocate memory */
    if (((unsigned int)(source - *dest)) < dest_size)
        return memmove(*dest, source, source_size);

    /* reallocate since source is possibly larger than dest */
    if (source_size > dest_size)
        *dest = (char *)realloc(*dest, source_size);

    return memcpy(*dest, source, source_size);
}