Good, but I'd do one modification -- always write a null byte at the end. Otherwise you end up with a non-null-terminated string and that's bad. So, copy_sz

Good, but I'd do one modification -- always write a null byte at the end. Otherwise you end up with a non-null-terminated string and that's bad. So, copy_sz = src_sz < (dest_sz - dest_off) ? src_sz : (dest_sz - dest_off - 1); ... *dest_end = '\0';