Message-ID: <4BD989A9.4080402@towo.net>
Date: Thu, 29 Apr 2010 15:29:13 +0200
From: Thomas Wolff <towo@towo.net>
User-Agent: Mozilla/5.0 (Windows; U; Windows NT 5.1; en-US; rv:1.9.1.9) Gecko/20100317 Lightning/1.0b1 Thunderbird/3.0.4
MIME-Version: 1.0
To: cygwin@cygwin.com
Subject: Re: select() hanging after terminal killed
References: <201004291053.o3TAr15g018361@mail.bln1.bf.nsn-intra.net> <4BD96D59.7080808@gmx.de>
In-Reply-To: <4BD96D59.7080808@gmx.de>
Content-Type: text/plain; charset=windows-1252; format=flowed
Content-Transfer-Encoding: 7bit
Mailing-List: contact cygwin-help@cygwin.com; run by ezmlm
Sender: cygwin-owner@cygwin.com
Mail-Followup-To: cygwin@cygwin.com

On 29.04.2010 13:28, Matthias Andree wrote:
> Am 29.04.2010 12:53, schrieb Thomas Wolff:
>
> [on closed terminal]
>    
>> On Linux, select() indicates an exception and EIO.
>> On SunOS, select() indicates both an exception and input (weird),
>>      
> Not weird, you appear to be misunderstanding select().
> An IEEE Std 1003.1 compliant select():
>
>   - only states that a subsequent read() will *not block*
>     this includes EOF and error, as they make read() return without blocking)
>
>   - makes *no statements about success*
>    
Oh, right, so apparently Linux is wrong here (since it does not report 
read availability...).

>> On Cygwin, the following is observed:
>> * EOF is not signalled on read(); rather EIO is indicated right away.
>>    (Maybe not too bad, an application can handle that as well.)
>> * select() with timeout hangs.
>>
>> Especially the latter can hardly be handled by an application.
>>      
> Pointers for workarounds: alarm(), signal().
>    
So I could setup alarm() to get myself signal()ed while waiting in a 
long sleep().
But the granularity is in seconds only, so this is not a substitute for 
most use cases typically handled by calling select().
Thanks for the information anyway.

------
Thomas

--
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