[_dain_]

As you add more code between the "open" and the "close", you introduce more opportunities for control flow to accidentally skip the "close" (leak), or call it more than once (double-free). It forces you to use single-return style, which can make some things very awkward to express.

You're basically doing "defer"-style cleanup manually; you may as well just use the real "defer" if your compiler supports it. It's supposed to be official in a future standard, too.