linux-kernel - Re: [PATCH 1/2] remove all uses of printf's %n

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Date:	Mon, 16 Sep 2013 11:03:29 -0700
From:	Joe Perches <joe@...ches.com>
To:	George Spelvin <linux@...izon.com>
Cc:	keescook@...omium.org, akpm@...ux-foundation.org,
	dan.carpenter@...cle.com, JBeulich@...e.com,
	kosaki.motohiro@...il.com, linux-kernel@...r.kernel.org,
	penguin-kernel@...ove.sakura.ne.jp, viro@...iv.linux.org.uk
Subject: Re: [PATCH 1/2] remove all uses of printf's %n

On Mon, 2013-09-16 at 13:21 -0400, George Spelvin wrote:
> > My thought was to add a seq_last_len()
> 
> In addition to adding per-call overhead to support a rarely-used feature
> (while ->pos comes for free), this has the downside that it matters how
> many separate calls are used to generate the string.
> 
> The advantage of the "read ->pos before and after" technique is that
> you can have an arbitrary number of output calls in between.
> Including things like seq_path(), seq_bitmap(), etc.
> 
> If you have the printing done in a subroutine (as in the net/ipv4
> directory), it would be annoyingly subtle if seq_puts("foobar")
> were not equivalent to seq_puts("foo"); seq_puts("bar").

It's already true that those aren't equivalent.
	seq_puts(seq, "short ");
	set_puts(seq, "string");
may fit the first bit into the output buffer but not the last
where
	setq_puts(seq, "short string");
would not fit at all.

btw: who are you?  Is your name really George Spelvin?



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