QUser class wanted



  • In my experiences with Qt5 so far, it has proved admirably cross-platform.

    I would like a QUser class which abstracts the process of identifying the current user in a native application.

    https://stackoverflow.com/questions/842059/is-there-a-portable-way-to-get-the-current-username-in-python indicates some of the difficulties. (I happen to use Python/PyQt, but the fact that it's Python is just an illustration.)

    Note that I am not looking for a solution which involves environment variables, it must make secure OS calls to identify the user and provide what it can (e.g. at minimum the username) back to the outside world.


  • Moderators

    Hi! For POSIX systems, see man getuid(2) and man getlogin_r(3) as the starting point for your implementation.


  • Lifetime Qt Champion

    Hi,

    Do you mean something like kdesudo ?



  • @Wieland Sounds fine for my Linux, but for Windows? That's not POSIX, is it? I want x-platform.



  • @SGaist said in QUser class wanted:

    Hi,

    Do you mean something like kdesudo ?

    No, no, nothing like sudo! I just want to retrieve the current user information --- such as his name --- on Linux/Windows/MacWhatever. But by it making whatever native OS calls, not using environment variables which can be set to anything.

    Like @Wieland was indicating, I suspect that means calling get(e)uid un Linux, GetWindowsUsername or some-such under 'doze, etc. Then providing whatever info is common back to the class.


  • Moderators

    @JNBarchan said in QUser class wanted:

    I suspect that means calling get(e)uid un Linux, GetWindowsUsername or some-such under 'doze, etc. Then providing whatever info is common back to the class.

    Yes.



  • @Wieland said in QUser class wanted:

    @JNBarchan said in QUser class wanted:

    I suspect that means calling get(e)uid un Linux, GetWindowsUsername or some-such under 'doze, etc. Then providing whatever info is common back to the class.

    Yes.

    Yes, as in: yes, that's what's needed but there isn't presently something I can use which does this? Sorry, I'm not certain, I can't use the POSIX thing under Windows, or can I?


  • Moderators

    AFAIK there is nothing like that "QUser" readily available. So I think you have to build your own one. For this you'd have to write platform specific code for POSIX, Windows, and all the other systems you need to support. There are a couple of ways how to implement that in actual code. In its simplest form it would look like:

    QString JNB::getUserName()
    {
        QString userName;
    
    #ifdef Q_OS_LINUX
        // call linux API, like getuid()
    #endif
    
    #ifdef Q_OS_WIN32
        // call Windows API
    #endif
    
        return userName;
    }
    


  • @Wieland
    OIC, yes. My prob is that I'm Python/PyQt, I could do that in 10 seconds in C++ :)
    That's why I'd like Qt to kindly provide just this in their cross-platform library. Please!


  • Qt Champions 2016

    Can't you create your code in C++ and just provide bindings for python (like PyQt does)? That's what I'd attempt. :)


  • Moderators

    Oh, okay. Python already has some built-in stuff for you, Miscellaneous operating system interfaces.



  • @kshegunov
    I share the code with others. We don't write extra bits in C++, compile them cross-platform, share the code... We use Python. Think as: these guys don't use C++. That's why Qt5 + PyQt5 is just marvellous for x-platform. It provides loads of other things (files, windows, ...) x-plat, I'd like it to provide user info.
    :)


  • Moderators

    @kshegunov said in QUser class wanted:

    Can't you create your code in C++ and just provide bindings

    Ever done that? No fun at all...



  • @Wieland said in QUser class wanted:

    @kshegunov said in QUser class wanted:

    Can't you create your code in C++ and just provide bindings

    Ever done that? No fun at all...

    Yeah, thanks for that observation. I haven't tried, but it sounds alarm bells...


  • Moderators

    I'm afraid there's too much of a divergence on what a "user" means on different platforms to enclose it in such class. I'm no Linux programmer, but on Windows at least you've got your currently logged in user, the user that the application is run with (might not be the same at all), the user that owns a particular thread, elevation, and then there's client impersonation mechanism... I doubt that these concepts map easily to other platforms so that they could be captured under a simple QUser umbrella.


  • Qt Champions 2016

    @Wieland said in QUser class wanted:

    @kshegunov said in QUser class wanted:

    Can't you create your code in C++ and just provide bindings

    Ever done that? No fun at all...

    Nope, that's why I phrased it as a question.



  • @Chris-Kawa said in QUser class wanted:

    I'm afraid there's too much of a divergence on what a "user" means on different platforms to enclose it in such class. I'm no Linux programmer, but on Windows at least you've got your currently logged in user, the user that the application is run with (might not be the same at all), the user that owns a particular thread, elevation, and then there's client impersonation mechanism... I doubt that these concepts map easily to other platforms so that they could be captured under a simple QUser umbrella.

    All of them provide a user name, for example. Which happens to be what I need. Actually, client impersonation/elevation maps quite well to Linux real versus effective uid. If you take, say, the POSIX abstraction it does find common ground with useful information. It was just a hope that Qt might help me :)



  • @Wieland said in QUser class wanted:

    Oh, okay. Python already has some built-in stuff for you, Miscellaneous operating system interfaces.

    I'm afraid that's why I quoted https://stackoverflow.com/questions/842059/is-there-a-portable-way-to-get-the-current-username-in-python. The point is nobody found a layer which did work x-plat.


  • Qt Champions 2016

    @JNBarchan said in QUser class wanted:

    All of them provide a user name, for example. Which happens to be what I need.

    Mind me asking what for, as this is rather odd requirement?



  • @kshegunov said in QUser class wanted:

    @JNBarchan said in QUser class wanted:

    All of them provide a user name, for example. Which happens to be what I need.

    Mind me asking what for, as this is rather odd requirement?

    Wow, I think it's a not uncommon requirement! Of course I don't mind you asking.

    I would like to affect my Qt application's UI depending on who the end user is, in whatever fashion. So I need to identify the user, username would be fine.

    My targets may be Windows or Linux, users might be a single user on own PC or member of team logged onto a network. Obviously I know the information about the user varies across these, I'll take whatever I'm given.

    I don't like the idea of retrieving that information through environmental variables a user can simply set. @Wieland's code looks like a good start, but it's inconvenient for me to have to do that via C++, so I'd like friendly Qt to kindly offer that as a x-platform utility function (which the next release of PyQt will pick up and make available to me) :)


  • Qt Champions 2016

    @JNBarchan said in QUser class wanted:

    Wow, I think it's a not uncommon requirement! Of course I don't mind you asking.

    Some people do and I have never needed it, so I'd qualified it as uncommon in my mind. ;)

    My targets may be Windows or Linux, users might be a single user on own PC or member of team logged onto a network. Obviously I know the information about the user varies across these, I'll take whatever I'm given.

    If python allows you to directly call the system you could try whoami which supposedly should work on both windows and linux. If you don't have system (or akin) in python, alternatively you could use QProcess to invoke the command line interpreter and run it. See for example:

    https://technet.microsoft.com/en-us/library/cc771299(v=ws.11).aspx
    http://www.linfo.org/whoami.html

    I can't tell you how it retrieves that information though, so it may very well depend on the environment variables as well.



  • @kshegunov said in QUser class wanted:

    If python allows you to directly call the system you could try whoami which supposedly should work on both windows and linux. If you don't have system (or akin) in python, alternatively you could use QProcess to invoke the command line interpreter and run it.

    Thanks, but I'd rather use environment variables than run an OS command!! I'll look through the python os module and find some calls which give me the best from what's there, I think.


  • Qt Champions 2016

    The last option is to write the C++ class, write a proposal in the bug tracker where you say why you need this and where it should go, provide testing and documentation for that code and have it included in Qt. Then wait (or appeal to the devs) for it to get python binding.
    It's not exactly a very quick process, but if you think it's needed we would all appreciate your effort. :)



  • @kshegunov
    Did I mention I kinda want to start using this on Monday...? ;-)

    Yep, point taken. I have only just gotten involved in Qt, and Python. Thanks for suggestions.


  • Moderators

    @JNBarchan said in QUser class wanted:

    I would like to affect my Qt application's UI depending on who the end user is

    Why do you need user name for that? Isn't it just user configuration stored in user home directory (UNIX/LINUX) or user part of the registry on Windows? For that you can use QSettings.



  • @jsulm said in QUser class wanted:

    @JNBarchan said in QUser class wanted:

    I would like to affect my Qt application's UI depending on who the end user is

    Why do you need user name for that? Isn't it just user configuration stored in user home directory (UNIX/LINUX) or user part of the registry on Windows? For that you can use QSettings.

    That works where the UI alterations are purely controlled by a user's own "preferences". However, not when the rules are imposed by the system/Administrator, and are not to be overridden by some user's fancy. For example, some areas of the system are only to be accessible to "administrators" and not to "plain users". I don't want some end user to go editing his own file/registry to switch on things he should not have access to!

    Doubtless in practice this will be implemented by assigning "roles" to users for the checks, rather than directly on the username. But I need to know the name securely to determine the correct role(s). Role membership may be implemented via the application having a database table of "username+role", or possibly via native Linux/Windows "group" membership, if I can determine that similarly securely (again, QUser class could have included group membership cross-platform just like username, as it is I would have to write that myself with the same problems as for username).

    Additionally, I may wish to log the user's name in log files from the application or from MySQL. Again, I want the secure, correct user's name, not what he might fancy poking into a settings.ini file/registry, environment variable or similar!


Log in to reply
 

Looks like your connection to Qt Forum was lost, please wait while we try to reconnect.