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Date: Thu, 4 Aug 2005 10:39:09 +0400
From: Andrey Chernov <ache@FreeBSD.ORG>
To: Maxim.Sobolev@portaone.com, Dan Nelson <dnelson@allantgroup.com>,
	"current@freebsd.org" <current@FreeBSD.ORG>
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Subject: Re: Sub-optimal libc's read-ahead buffering behaviour
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On Thu, Aug 04, 2005 at 10:02:51AM +0400, Andrey Chernov wrote:
> But between read & seek character device itself can move its pointer in 
> anyplace.

Well, this phrase is incorrectly constructed. I mean: by reading 
from the character device, the pointer can be moved to same unpredictable 
places, say, become negative, or other overflow happens.

So (considering changing content like /dev/mem too), any buferization is 
potentially dangerous here. fseek traditionally used as buferization 
break, in case, say, between fread and fwrite. In case SEEK_CUR still uses 
the buffer, it probably should not for character device.

-- 
http://ache.pp.ru/