Message-ID: <4D74BDB0.1060206@tweerlei.de>
Date: Mon, 07 Mar 2011 12:12:48 +0100
From: Robert Wruck <wruck AT tweerlei DOT de>
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; de; rv:1.9.2.9) Gecko/20100915 Thunderbird/3.1.4
MIME-Version: 1.0
To: cygwin AT cygwin DOT com
Subject: Re: 1.7.8: write fails with EAGAIN
References: <4D72992D DOT 4090007 AT tweerlei DOT de> <20110307103951 DOT GL6393 AT calimero DOT vinschen DOT de>
In-Reply-To: <20110307103951.GL6393@calimero.vinschen.de>
Content-Type: text/plain; charset=UTF-8; format=flowed
Content-Transfer-Encoding: 7bit
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

Hi,

> Hang on, you are saying that a *blocking* write(2) to a pipe returns
> with EAGAIN?  Are you sure?  It would be quite a surprise if git would
> actually do that.  EAGAIN is only an expected error for non-blocking
> I/O, so applications which use blocking I/O usually only test for EINTR.

since in the interesting case I'm writing to stdout (fd=1) I don't know 
whether that was initially opened with O_NONBLOCK - but I wouldn't think so.

I was able to reproduce this as follows:

./writetest infile | cat > outfile

where infile is a "large" file.
The output is:

$ ./writetest infile | cat > test.out
writing 78954543 bytes...
result is -1, errno is 11
writing 78954543 bytes...
result is -1, errno is 11
...

This does not happen for "small" files:

$ ./writetest infile2 | cat > test.out
writing 10978848 bytes...
result is 10978848, errno is 0

Also, I tried this with the same cygwin version on Win7/64-bit and this 
did not happen even for a 1GB file.


-Robert

--
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