Gnome Session Restore

A simple utility to save and restore gnome sessions.

Examples

gnome-session-restore --file test.json save

-- later -- 

gnome-session-restore --file test.json restore

Requirements

Since gnome 40 and upwards made the org.gnome.Shell.Eval only accessible in unsafe-mode this utilty needs a extension that restores the functionality that it relied on before this change (without enabling unsafe-mode).

https://github.com/Clueliss/windowctl

I initially used a workaround that temporarily enabled unsafe mode via another extension, but that was obviously bad and I really only did it as a quick and dirty hack to get it working again.

How it works

Saving

1. Query the above mentioned extensions' dbus interface for window metadata. This metadata will contain stuff like, window geometry, process id, window manager class and possibly a gtk app id.

2. Try to find the command that belongs to a specific window. This can be done in one of three ways, which will be tried one by one.

   1. If that application has a gtk app id, this normally means that a desktop file with exactly that name exists. If it does the desktop file will be used to execute it.
   2. If that application has a sanboxed app id this normally means that a desktop file with exactly that name exists. If it does the desktop file will be used to execute it.
   3. Consider the window manager class, and the name of the executable that is found via /proc/{pid}/cmdline. If a desktop file with any of those names exists it will be used.
   4. If no desktop file could be found the only option left is taking the command found in /proc/{pid}/cmdline

3. Save all the extracted metadata in a json file.

The reason for considering /proc/{pid}/cmdline only as a last resort is that in my testing, just executing this is often a poor representation of what launching a program via it's desktop entry is like. Which also makes it a poor way to restore sessions.

Restoring

1. Read the given json file
2. Execute all the given commands
3. Try to move the windows to the position they were previously in. This will not always work since it relies on the window manager class to track down the resulting windows and some applications do not set this for some reason. And windows don't really want to be moved when they cover a whole screen; even without being fullscreen (not sure why that is). This is also done via the dbus interface of my extension.