Recover XDG_CURRENT_DESKTOP's value?

candy76041820

On linux (a weird private distro moified after Ubuntu):

pkexec myprog

gets myprog running as root, but loses environment variables.
I made a org.myorg.myprog.policy under /usr/share/polkit-1/actions, specified allow_gui to true, and myprog gets DISPLAY and XAUTHORITY back.
Question: myprog's GUI theme looks different from when it's not sudo-ed due to absence of XDG_CURRENT_DESKTOP variable. Can I recover it WITHOUT use of argv or some IPC trick?

(Also, I don't want to

pkexec env VAR=VALUE myprog

because it's too ugly, and the password dialog would be showing the user's launching env instead of myprog.)

SGaist

Hi,

Since it's an environment variable you can use
qEnvironmentVariable.

candy76041820

@SGaist No.

jsulm

@candy76041820 said in Recover XDG_CURRENT_DESKTOP's value?:

No

Why not?

candy76041820

@jsulm Didn't I say that pkexec-ing myprog peels the environment variables off?

candy@vbuntv:~/T$ more T.cpp
#include <iostream>
#include <string>

int main(int argc, char **argv, char **envp){
    std::string keys[]={"DISPLAY=", "XAUTHORITY=", "XDG_CURRENT_DESKTOP="};
    while(envp && *envp){
        for(const std::string &key: keys){
            std::string var=*envp;
            if(var.starts_with(key)){
                std::cout<<var<<std::endl;
                break;
            }
        }
        envp++;
    }
    return 0;
}

candy@vbuntv:~/T$ g++ -std=c++20 T.cpp && ./a.out
XDG_CURRENT_DESKTOP=ubuntu:GNOME
DISPLAY=:10.0
candy@vbuntv:~/T$ pkexec `pwd`/a.out
#No output at all.

candy@vbuntv:~/T$ env | grep -E "DISPLAY|XAUTHORITY|XDG_CURRENT_DESKTOP"
XDG_CURRENT_DESKTOP=ubuntu:GNOME
DISPLAY=:10.0
candy@vbuntv:~/T$ pkexec env | grep -E "DISPLAY|XAUTHORITY|XDG_CURRENT_DESKTOP"
#Nothing.

jsulm

If I'm not mistaken @SGaist wanted to suggest that your application changes/sets the env variable using https://doc.qt.io/qt-5/qtglobal.html#qputenv

candy76041820

@jsulm How can I set it back when I don't know its old value??

SGaist

Based on the pkexec documentation you can't do what you are trying. The environment is set to a minimal state that excludes the variables you are interested in.

If you want their values in your application, you will have to pass them as command line parameters.

However, based on the variable you are looking for, it seems you want to run a GUI as root, which is usually a bad idea.