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SubjectRe: [PATCH 07/14] lib/vsprintf.c: slightly refactor vscnprintf()
From
On Mon, Nov 23, 2015 at 11:29 PM, Rasmus Villemoes
<linux@rasmusvillemoes.dk> wrote:
> If we're given a size of 0, the vsnprintf() won't have any side
> effects, and neither "i < size" or "size != 0" will trigger. So we
> might as well return 0 immediately.
>
> Signed-off-by: Rasmus Villemoes <linux@rasmusvillemoes.dk>
> ---
> lib/vsprintf.c | 7 ++++---
> 1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/lib/vsprintf.c b/lib/vsprintf.c
> index 8af5535fd738..e22a6189548f 100644
> --- a/lib/vsprintf.c
> +++ b/lib/vsprintf.c
> @@ -2036,13 +2036,14 @@ int vscnprintf(char *buf, size_t size, const char *fmt, va_list args)
> {
> int i;
>
> + if (unlikely(!size))
> + return 0;
> +

Might it potentially shadow any issue when run vsnprintf(buf, 0, fmt,
args); with certain arguments?
I can imagine something like %pV with unstable pointer.

> i = vsnprintf(buf, size, fmt, args);
>
> if (likely(i < size))
> return i;
> - if (size != 0)
> - return size - 1;
> - return 0;
> + return size - 1;
> }
> EXPORT_SYMBOL(vscnprintf);
>
> --
> 2.6.1
>
> --
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--
With Best Regards,
Andy Shevchenko


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