Cannot run an app that uses GTK without root

shelper

12/10/23, 3:03 AM

I wrote a very simple executable in C++, that uses opencv with gtk3 to load an image in jpeg format and show it, When I run it without sudo, I got error:

Gtk-WARNING **: 21:58:36.172: Could not load a pixbuf from icon theme.
This may indicate that pixbuf loaders or the mime database could not be found.
**
Gtk:ERROR:../../../../gtk/gtkiconhelper.c:494:ensure_surface_for_gicon: assertion failed (error == NULL): Failed to load /org/gtk/libgtk/icons/16x16/status/image-missing.png: Fatal error reading PNG image file: Invalid IHDR data (gdk-pixbuf-error-quark, 0)
Bail out! Gtk:ERROR:../../../../gtk/gtkiconhelper.c:494:ensure_surface_for_gicon: assertion failed (error == NULL): Failed to load /org/gtk/libgtk/icons/16x16/status/image-missing.png: Fatal error reading PNG image file: Invalid IHDR data (gdk-pixbuf-error-quark, 0)
[1]    6329 IOT instruction  ./main

But if I run it with sudo, everything works. I searched around and tried all the suggested commands that I found online including:

sudo apt reinstall libgdk-pixbuf2.0-0
sudo /usr/lib/x86_64-linux-gnu/gdk-pixbuf-2.0/gdk-pixbuf-query-loaders --update-cache
sudo update-mime-database /usr/share/mime
sudo chmod -R uga-x /usr/share/mime; sudo chmod -R uga+X /usr/share/mime

None of above works, I also restarts the system after running all the steps, still does not work, need help.

I am on Ubuntu 18.04, in WSL2, I also tested the binary in a freshly installed ubuntu 20.04 in WSL2 and the same thing happens. The source code and binary can be downloaded at https://github.com/shelper/vscode_cpp_cmake_example/releases/tag/test.

409

1 + 6

gtk

windows-subsystem-for-linux

shelper

12/10/23, 3:49 AM

updated, i am on ubuntu 18.04 on wsl2, i am not sure if i understand you, but all the commands i listed above, need to be run with sudo and i also updated access with chmod...

NotTheDr01ds

12/10/23, 10:25 AM

Does it happen with any "out-of-the-box" Gtk app, or just your code? If just yours, can you add a possible [MRE](https://stackoverflow.com/help/minimal-reproducible-example), and I'll see if I can reproduce and help out. Also, does `wsl --version` show any results? If so, probably worth adding them to the question as well so I can try a similar environment. Thanks!

NotTheDr01ds

12/10/23, 10:32 AM

Also, is `XDG_DATA_DIRS` set and valid per [this answer](https://askubuntu.com/a/1388056/1165986)?

shelper

12/10/23, 6:53 PM

Its just my code, and i also tried to set XDG_DATA_DIRS, which is unset originally. I updated my question with src and binary for download and test

NotTheDr01ds

12/10/23, 8:00 PM

Ah, I'm sorry I pushed to repost over here then. It probably would be better on Stack Overflow as you thought, but it would have been closed anyway without an MRE. However, we could have reopened it there with the MRE. I'll leave it to you where you want to leave it. My personal opinion will be that, if you have source code in the question itself, you'll likely stand a better chance of having it answered on Stack Overflow. I'll continue to look at it regardless, though, but it may be out of my depth.

shelper

12/11/23, 3:09 AM

@NotTheDr01ds see my own answer below. it is kinda solved but leaves new question..

Score:1

Ubuntu

shelper

12/11/23, 3:08 AM

I found this article at https://devforum.play.date/t/segmentation-fault-running-playdatesimulator-on-linux/3360/4, I then tried the sed -i s/png_/PNG_/g ./main, I got error saying undefined symbol: G_free. I then rebuild the binary and run sed -i s/png_/PNg_/g ./main, everything works now. I believe this is due to the gtk-3 dev package I used to build OpenCV has ABI compatibility with the one in my system. However, what I don't understand is that why sudo is able to run the binary without problem.

+ 2

NotTheDr01ds

12/11/23, 5:27 AM

Good find! I'm wondering - Is the image that you are trying to load on a Windows mount such as `/mnt/c`? Or is it on the WSL2 ext4 filesystem?

shelper

12/11/23, 7:20 PM

it is in WSL2, the same folder as the main that is in my home directory in WSL2

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EN: Cannot run an app that uses GTK without root

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