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Re: blocking socket is nonblocking after calling gnulib select() in wind

From: Bastien ROUCARIES
Subject: Re: blocking socket is nonblocking after calling gnulib select() in windows
Date: Thu, 21 Apr 2011 22:17:39 +0200

On Thu, Apr 21, 2011 at 8:59 AM, Ray Satiro <address@hidden> wrote:
>> On Wed, Apr 20, 2011 at 7:17 PM, Bastien ROUCARIES
>> <address@hidden>  wrote:
>> >> Is the gnulib select() only intended to be used with  nonblocking sockets
> on
>> >> windows?
>> >
>> > I have just tested  the program at the end of the file, it thread is
>> > blocked when enable =0  (block socket) and enable=1 it fail with
>> >
>> >  So i possible stragegy will be:
>> > 1. createathread TID from parent
>> >  2. in TID do WSAIoctl(sock, SIO_ADDRESS_LIST_CHANGE,NULL, 0, NULL,
>> >  0,&bytes,NULL,NULL);
>> > 3. in  parent: if TID returned with  WSAEWOULDBLOCK tag socket non blocking
>> > 4. query running state of TID, if  suspended socket is blocking, kill
>> > thread and mark socket  blocking
>> It will not work using a thread (thread are not cancelable  under
>> windows), but using a new process with inherited socket it will  work
>> slow but a little bit as the projected openat function using  fork
> Hi, thanks for your replies guys.
> Bastien, The problem with sending io control codes is there will likely be
> unintended consequences if used as you theorize. From what I've seen so far
> there is no way to determine the blocking state without sending a control 
> code,
> or in other words, actually making the request. If the socket is blocking then
> it will block. If blocking, killing the thread that's waiting on the event 
> you'd
> be killing the waiting not the pending operation, although I haven't tested 
> that
> so I can't say for certain.
> api monitor shows:
> ntdeviceiocontrol(socket, event, ...
> If the socket is nonblocking the immediate return is STATUS_DEVICE_NOT_READY. 
> If
> it is blocking then the immediate return is   STATUS_PENDING and wsaioctl 
> waits
> for a signal which is set when the operation completes.
> I think for now I will submit code for Wget that will disable NBIO immediately
> after rpl_select() returns or instead use ms select() with FD_TO_SOCKET.
> Thanks,

What give FILE_MODE_INFORMATION query using NtQueryInformationFile on
(Handle) Socket ?


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