Cannot open res:// file from directory in exported project through FileDialog

[timvisee]

Godot version

v3.4.2.stable.official [45eaa2d]

System information

Ubuntu 21.10, Linux 5.15, GLES3, NVIDIA 495.46, GTX 2070,

Issue description

The FileDialog cannot open files from res:// when the file is in a sub directory, when the project is exported. Files are opened fine when they are in the root of res://.

Not being able to open them means that a file in a sub directory cannot be 'confirmed'. The 'Open' button or double clicking simply does nothing.

This only happens when the project is exported. Running from the editor works fine. I'm assuming this has to do with reading from the .pck file.

Steps to reproduce

See the attached project. Export with *.txt as non-resource, to include it in the export.

Run the project from the editor:

• Opening res://text.txt and res://sub/text.txt works fine.

Run the exported project:

• Opening res://text.txt works fine
• Opening res://sub/text.txt fails and does nothing

Minimal reproduction project

godot-res-error.zip

[timvisee]

This appears to have been fixed on master.

It is still broken in 3.4 however. I'd love to have this backported to 3.4. I'm unsure where the fix is implemented though.

In the meanwhile I've implemented a fix myself on the 3.4 branch. With extensive testing this seems to work fine. Though I'm not 100% sure this is the correct approach:
https://github.com/timvisee/godot/commits/3.4-fix-absolute-res

Updated project for 4.0, which again, works fine: godot-res-error-4.0.zip

[akien-mga]

Duplicate of #37646

[akien-mga]

Well maybe not strictly speaking a duplicate as this one is about FileAccess and not DirAccess, though it's probably the same underlying bug (which I tried to address or might have introduced myself in #31440). CC @RandomShaper