Re: [ptxdist] QUdpSocket does not work in qt5 - any tips?

[Michael Olbrich <m.olbrich@pengutronix.de>]

Hi,

On Sun, Nov 15, 2015 at 11:35:12AM +0000, Matthias Klein wrote:
> I can not get QUdpSocket working to receive broadcast messages with Qt5 from
> ptxdist (non GUI build).
> I have attached a minimal code example. Such code was working fine when
> building against Qt 4.8.7.
> I have tested the code on Windows with Qt 5.5.1 and under Debian Linux with
> Qt 5.3.2.
> 
> I also tried to build different versions of Qt with ptxdist: 5.4.1 and 5.5.1
> (I adapted the patches accordingly).
> 
> When the test programm runs I see that the receive queue fills in netstat
> -a:
> Proto Recv-Q Send-Q Local Address           Foreign Address         State
> udp     1024      0 (null):5025             (null):*
> I think that the bind works, but the packets are not delivered with the Qt
> signal.
> I tried to receive broadcast messages using plain C code (bind(),
> recvfrom(), etc.) which works fine.
> 
> Therefore I think it is a Qt problem. But I tested three different versions
> (5.4.2 from ptxdist and 5.4.1 + 5.5.1), that I can not believe it really.
> Does anyone successfully used QUdpSocket from a ptxdist Qt 5 build?

Try it with QT5_GLIB enabled. All Desktop Distributions use Qt with the
glib mainloop. Maybe there is a Bug in the non-glib file descriptor
handling code.

Michael

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