linux-kernel - Re: [PATCH 1/2] tomoyo: use vsnprintf() properly

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Message-ID: <304f443a-acda-6b31-78ac-fad205deb0ec@I-love.SAKURA.ne.jp>
Date:   Sun, 21 Aug 2022 12:39:52 +0900
From:   Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
To:     Al Viro <viro@...iv.linux.org.uk>
Cc:     linux-kernel@...r.kernel.org
Subject: Re: [PATCH 1/2] tomoyo: use vsnprintf() properly

On 2022/08/21 5:25, Al Viro wrote:
> Idiomatic way to find how much space sprintf output would take is
> 	len = snprintf(NULL, 0, ...) + 1;
> Once upon a time there'd been libc implementations that blew chunks
> on that and somebody had come up with the following "cute" trick:
> 	len = snprintf((char *) &len, 1, ...) + 1;
> for doing the same.  However, that's unidiomatic, harder to follow
> *and* any such libc implementation would violate both C99 and POSIX
> (since 2001).
> 	IOW, this kludge is best buried along with such libc implementations,
> nevermind getting cargo-culted into newer code.  Our vsnprintf() does not
> suffer that braindamage, TYVM.
> 
> Signed-off-by: Al Viro <viro@...iv.linux.org.uk>

Thank you. You can send this change via your tree if you like.

Acked-by: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>