QT deployed executable crashes on some computers

[Lati]

@JonB I am not one of that millions of coders (or even if I used it, I never had problems).

In the code, I replaced the getenv part using _dupenv_s as following (which will be valid with the next release):

    char* buf = nullptr;
    size_t sz = 0;
    if (_dupenv_s(&buf, &sz, "programXROOT") == 0 && buf != nullptr)
    {
        programXRootDirectory = buf;
        free(buf);
    }
    else
    {
        QMessageBox msgBox;
        msgBox.setText("Environmental variable is missing!");
        msgBox.exec();
    }

Actually, after installation of this application, user has to create this environmental variable before starting the application. And seems like all the users have created the variable and there was no issue so far. But if a user would forget about this, it would be nightmare to find out the reason.

[JonB]

@Lati
Again for the record, the _dupenv_s (which btw is MSVC-only) you mention has nothing to do with the issue you are talking about. The extra parameters it takes are to do with copying the value, if found, into your own buffer. If it's not found:

If the variable is not found, then buffer is set to NULL, numberOfElements is set to 0, and the return value is 0 because this situation is not considered to be an error condition.

So the issue will rear its head again if code later tries to dereference the buf from the &buf passed in. Just as with the return result from getenv().

Purely as a by-the-by, I presume you are aware in the code you show (which perhaps is only intended as an example):

        programXRootDirectory = buf;
        free(buf);

This would not be a good idea --- programXRootDirectory is left pointing to freed memory! You'll get a different error/crash/behaviour if you then dereference that :)