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Message-ID: <1378944257.4714.45.camel@joe-AO722>
Date: Wed, 11 Sep 2013 17:04:17 -0700
From: Joe Perches <joe@...ches.com>
To: Tetsuo Handa <penguin-kernel@...ove.SAKURA.ne.jp>
Cc: linux-kernel@...r.kernel.org, kosaki.motohiro@...fujitsu.com,
keescook@...omium.org, fweisbec@...il.com,
dan.carpenter@...cle.com, devel@...verdev.osuosl.org,
gregkh@...uxfoundation.org, tushar.behera@...aro.org,
lidza.louina@...il.com, davem@...emloft.net, kuznet@....inr.ac.ru,
jmorris@...ei.org, yoshfuji@...ux-ipv6.org, kaber@...sh.net,
courmisch@...il.com, vyasevich@...il.com, nhorman@...driver.com,
netdev@...r.kernel.org, linux-sctp@...r.kernel.org
Subject: Re: [RFC PATCH] vsnprintf: Remove use of %n and convert existing
uses
On Thu, 2013-09-12 at 08:40 +0900, Tetsuo Handa wrote:
> Joe Perches wrote:
> > - seq_printf(m, "%s%d%n", con->name, con->index, &len);
> > + len = seq_printf(m, "%s%d", con->name, con->index);
>
> Isn't len always 0 or -1 ?
Right. Well you're no fun...
These uses would seem broken anyway because the
seq_printf isn't itself tested for correctness.
Hmm.
Also, there's a large amount of code that appears
to do calculations with pos or len like:
pos += seq_printf(handle, fmt. ...)
There are very few that seem to use it correctly
like netfilter.
$ grep -rP --include=*.[ch] "^[ \t]*\S[ \t\S]*\bseq_[v]?printf\b" *
Suggestions?
> int seq_vprintf(struct seq_file *m, const char *f, va_list args)
> {
> int len;
>
> if (m->count < m->size) {
> len = vsnprintf(m->buf + m->count, m->size - m->count, f, args);
> if (m->count + len < m->size) {
> m->count += len;
> return 0;
> }
> }
> seq_set_overflow(m);
> return -1;
> }
> EXPORT_SYMBOL(seq_vprintf);
>
> int seq_printf(struct seq_file *m, const char *f, ...)
> {
> int ret;
> va_list args;
>
> va_start(args, f);
> ret = seq_vprintf(m, f, args);
> va_end(args);
>
> return ret;
> }
> EXPORT_SYMBOL(seq_printf);
--
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