netdev - Re: [Suggestion] net/atm : for sprintf, need check the total write length whether larger than a page.

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Date:	Thu, 06 Dec 2012 09:15:10 +0800
From:	Chen Gang <gang.chen@...anux.com>
To:	chas williams - CONTRACTOR <chas@....nrl.navy.mil>
CC:	David Miller <davem@...emloft.net>, netdev <netdev@...r.kernel.org>
Subject: Re: [Suggestion] net/atm : for sprintf, need check the total write
 length whether larger than a page.

于 2012年12月05日 22:55, chas williams - CONTRACTOR 写道:
> On Wed, 05 Dec 2012 13:59:26 +0800
> 
> it doesn't seem like optimizing for this corner case is a huge
> concern.  the list cannot be infinitely long.
> 

  ok.


>>>>
>>>> By the way:
>>>>   will it be better that always let "\n" at the end ?
>>>>   (if count == PAGE_SIZE in a loop, we can not let "\n" at the end).
>>>
>>>    oh, sorry ! count will never >= PAGE_SIZE.
>>>
>>>    I think let "PAGE_SIZE - 2" instead of "PAGE_SIZE" in the loop, so we
>>> can make the room for the end of "\n".
>>>
>>>
>>>
>>    sorry, "PAGE_SIZE - 1" is enough, not need "PAGE_SIZE - 2".
> 
> did you mean '\0' instead of '\n'?  scnprintf() considers the trailing
> '\0' when formatting.

  no, originally, the end is "\n\0".

  I prefer we still compatible "\n" when the contents are very large.
  if count already == (PAGE_SIZE - 1), we have no chance to append "\n" to the end.

-		pos += sprintf(pos, "\n");
+		count += scnprintf(buf + count, PAGE_SIZE - count, "\n");


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-- 
Chen Gang

Asianux Corporation
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