tag_invalidate and tag_free

dogtag.c

void tag_invalidate(memory_t * memory) {
    TAG_TYPE * start = PTR_START_TAG(memory);
    *start = TAG_INVALID_VALUE;
 
    TAG_TYPE * end = PTR_END_TAG(memory);
    *end = TAG_INVALID_VALUE;
}
 
bool tag_free(memory_t * memory) {
    if (tag_underran(memory) || tag_overran(memory)) {
        return false;
    }
    
    tag_invalidate(memory);
 
    TAG_TYPE * start = PTR_START_TAG(memory);
    free(start);
    return true;
}