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Date: Wed, 19 Nov 2003 23:20:58 +0100
From: Rasmus Hahn <rassahah AT neofonie DOT de>
To: cygwin AT cygwin DOT com
Subject: Strange behaviour w/ read/write
Message-ID: <20031119222057.GA2601@hamburg.neofonie.local>
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Hi

I am using the current cygwin version (dll version 1-5-5-1) and see some
strange behaviour while using the read/write system calls.
In short: I open a file with mode O_RDWR|O_CREAT, write exactly 1MB into it
and then after seeking to position 0 read the Megabyte back. Strange things
seem to happen:
 - The File becomes larger during the whole process (up to some hundred bytes)
 - I get an end of file most of the times though i did not read all the 1MB
 - sometimes (5% of all runs) i get an EAGAIN error while reading the file

 has anybody experienced something similar? I make heavy use of threads writing
 different files at the same time (but not more than 1 thread per file).
 I suspect cygwin to write sometimes into the wrong file. I had not been able
 to reproduce this with a simple test-program, so i do not provide sample
 code here, but perhaps someone has experienced similar effects? And perhaps
 someone knows why i am getting EAGAIN-errors on diskfiles (i do not use
 nonblocking io)?

Greetings - Rasmus



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