DomainKey-Signature: a=rsa-sha1; c=nofws; d=sourceware.org; h=list-id
	:list-unsubscribe:list-subscribe:list-archive:list-post
	:list-help:sender:message-id:date:from:to:subject:references
	:content-type; q=dns; s=default; b=Vme4JvKv+Aa2BytQ8NV/4WTSGJu+K
	CDUcT50cxM+IGF1FwINNv3uPfydrJ07h3UlbD3rw5DHbGqzlwSVe62Mr2gvcRxG+
	FAO0WEhcZE+nD3rBmiiRTRx+a5nHDmX02ZWvrN845ePkZNBH7mY5dHdFqI/PjNo1
	IZeeZAjfqM0RNQ=
Mailing-List: contact cygwin-help AT cygwin DOT com; run by ezmlm
Sender: cygwin-owner AT cygwin DOT com
Mail-Followup-To: cygwin AT cygwin DOT com
Message-ID: <5a385ced.195b9d0a.d434.5400@mx.google.com>
Date: Mon, 18 Dec 2017 16:27:25 -0800 (PST)
From: Steven Penny <svnpenn AT gmail DOT com>
To: cygwin AT cygwin DOT com
Subject: Re: Wrong file position after writing 65537 bytes to block device
References: <20171218131035 DOT GB11285 AT calimero DOT vinschen DOT de>
Content-Type: text/plain; charset=utf8; format=flowed
User-Agent: Tryst/2.0.1 (github.com/svnpenn/tryst)

On Mon, 18 Dec 2017 14:10:35, Corinna Vinschen wrote:
> In general, the writes on disk devices is sector-oriented.  Howewver,
> in this case ftell should have returned 65536.  The problem here is
> that the newlib implmentation of ftell/ftello performs an fflush
> when called on a write stream since about 2008 to adjust for appending
> streams.  Given your example (thanks for the testcase!) this seems
> pretty wrong.  Looking further it turns out that neither glibc nor BSD
> actually calls fflush in this case.  There's only a special case for
> appending streams, but this calls lseek, not fflush.
> 
> Looks like a patch is required.  Stay tuned.

is it though? he says "write 65536 + 1 bytes", but as far as i can tell, you
cant do that. quoting myself:

> Seeking, reading and writing must all be done in multiples of sector size, in
> my case 512 bytes

http://web.archive.org/web/stackoverflow.com/questions/37228874/how-to-fwrite-to-removable-volume

so it would make sense that the position becomes "65536 + 512"


--
Problem reports:       http://cygwin.com/problems.html
FAQ:                   http://cygwin.com/faq/
Documentation:         http://cygwin.com/docs.html
Unsubscribe info:      http://cygwin.com/ml/#unsubscribe-simple