linux-kernel - Re:Re: [PATCH] lib: string: reduce unnecessary loop in strncpy

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Message-ID: <fd65c09.2464.16e1fa59f3b.Coremail.liuxiang_1999@126.com>
Date:   Thu, 31 Oct 2019 10:29:38 +0800 (CST)
From:   "Liu Xiang" <liuxiang_1999@....com>
To:     "Rasmus Villemoes" <linux@...musvillemoes.dk>
Cc:     linux-kernel@...r.kernel.org
Subject: Re:Re: [PATCH] lib: string: reduce unnecessary loop in strncpy











At 2019-10-30 22:59:58, "Rasmus Villemoes" <linux@...musvillemoes.dk> wrote:
>On 30/10/2019 15.14, Liu Xiang wrote:
>> Now in strncpy, even src[0] is 0, loop will execute count times until
>> count is 0. It is better to exit the loop immediately when *src is 0.
>
>Please read "man strncpy".
>
>There's a reason the loop is written in that somewhat convoluted way:
>The behavior of strncpy is mandated by the C standard, and if the src
>string is shorter than the destination buffer, the rest must be
>0-filled. So if we hit a nul byte before running out of count, we keep
>copying that nul byte to the rest of the destination.
>
>Rasmus

Hi Rasmus,

Thanks for your explanation. I ignored the C library standard.

Regards

Liu Xiang