Is it ok to redistribute Qt library?



  • happy new year friends :)

    I just made a runtime package for Qt5 (debian + rpm). It's aimed to ease deployment of proposed Qt5 programs in public computers in our university. As far as I know there is no problem with redistribution of code for Linux. Is there?

    Unfortunately on some machines in OS lab, we have no Linux installation. I'm not aware of any package management system for Windows. (like apt-get or yum). So I just make a installer that copies a couple of DLLs (Qt5 + MinGW runtime + MSVCRT) in windows system directory. It's supposed to remove need of copying DLLs beside applications and reduce redundancy.

    Just wonder if it's legal to publish it on sourceforge or not? It's a combination of binaries compiled from LGPL + GPL + and some closed-source precompiled libraries...

    !http://s2.picofile.com/file/7604754836/1.png(1)!
    !http://s1.picofile.com/file/7604755157/2.png(2)!
    !http://s2.picofile.com/file/7604755371/3.png(3)!


  • Moderators

    Happy new year, soroush. :)

    As far as I know, yes it is legal to distribute Qt runtime files, as long as you follow the terms specified in the LGPL. This thread contains some more info: http://qt-project.org/forums/viewthread/2428 , but it's best to consult an actual lawyer.

    Some things I'd like to add:

    • At the bottom of this page, it says "... the Qt logo is a registered trade mark of Digia plc", so I'm not sure if you're allowed to use the Qt logo in your installer. Contact Digia to ask.
    • I strongly suggest you don't install any DLLs into the Windows system directory -- that directory is for core system files only. Instead, install the DLLs somewhere else (e.g. C:\Qt or C:\Program Files\Qt), and add that folder to the system PATH
    • I'm confused by "Qt 5.0.0 Runtime libraries version 0.1.0"; how do you envision "Qt 5.0.0 Runtime libraries version 0.2.0" to be different? And what how will your installer be labelled when Qt 5.0.1 is released?

  • Moderators

    I also noticed that apart from Qt libs you include a whole bunch of other libraries like OpenSSL, ICU, and whatever is down the scrolling list ;) You should check if licenses for those allow this too.
    Probably yes, but it is easy to sometimes fall into that trap.

    Btw. I always thought DBus was a linux specific thingie? Is it also available on Windows?


  • Moderators

    [quote author="Krzysztof Kawa" date="1357134040"]Btw. I always thought DBus was a linux specific thingie? Is it also available on Windows?[/quote]The D-Bus project has officially accepted the Windows port into their code base (http://www.freedesktop.org/wiki/Software/dbus#Windows_port ), but I get the impression that it's not very stable yet.



  • [quote author="JKSH" date="1357129781"]

    • At the bottom of this page, it says "... the Qt logo is a registered trade mark of Digia plc", so I'm not sure if you're allowed to use the Qt logo in your installer. Contact Digia to ask.
      [/quote]
      Good to know. I will do so
      [quote author="JKSH" date="1357129781"]
    • I strongly suggest you don't install any DLLs into the Windows system directory -- that directory is for core system files only. Instead, install the DLLs somewhere else (e.g. C:\Qt or C:\Program Files\Qt), and add that folder to the system PATH
      [/quote]
      I just noticed that today and changed my installer :) Having a little experience with MS Windows, it looks strange and irregular to me!

    [quote author="JKSH" date="1357129781"]

    • I'm confused by "Qt 5.0.0 Runtime libraries version 0.1.0"; how do you envision "Qt 5.0.0 Runtime libraries version 0.2.0" to be different? And what how will your installer be labelled when Qt 5.0.1 is released?
      [/quote]

    Well, it's a little bit of trick there! First one in Qt version and second is Build version. Each Qt version is supposed to have a series of builds that they will tagged with some phrases. For example for Qt 5.0.0 there will be 0.1.0-mingw-64, 0.1.0-msvc11-64, 0.1.0-mingw-32, 0.1.0-msvc11-32. And when ready, in another compile I may fix some configuration bugs, apply more optimization, or change installer itself. Then for Qt 5.0.0 , build versions will be 0.1.1-mingw-64, 0.1.1-msvc11-64, 0.1.1-mingw-32, 0.1.1-msvc11-32 ... For Qt 5.0.1 versions will restart to 0.1.0.

    [quote author="Krzysztof Kawa" date="1357134040"]
    Btw. I always thought DBus was a linux specific thingie? Is it also available on Windows?[/quote]

    [quote author="JKSH" date="1357135056"]The D-Bus project has officially accepted the Windows port into their code base (http://www.freedesktop.org/wiki/Software/dbus#Windows_port ), but I get the impression that it's not very stable yet.
    [/quote]

    I made a Windows Service using startsrv that runs dbus-daemon in background. (In the newer version of installer there is a choice to start that service) DBus works pretty fine for me on windows. Since it has been officially approved windows port, I don't think of any problem. It has a lot of inconsistent code that makes it very difficult to compile on windows, but in runtime looks pretty stable.


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