Workaround gnome-shell disabling Eval by injecting js with gdb; no need to restart or poke the GUI!

enable_eval.bash

#! /usr/bin/env nix-shell
#! nix-shell -p gdb psmisc fzf -i bash

# Workaround gnome-shell disabling Eval by injecting js with gdb; no need to restart or poke the GUI!
# https://askubuntu.com/questions/1201849/invoking-gnome-show-applications-from-command-line
# https://askubuntu.com/questions/1412130/dbus-calls-to-gnome-shell-dont-work-under-ubuntu-22-04


#TODO clean this up
#TODO extend this to load plugins at runtime? (well, unneeded once you have Eval access I guess, because you can then use it like lg.)


#alternatively, use this shebang:
#! /usr/bin/env bash

invoke_gdb() {
  #string like:          `-Xwayland,7747 :0 -rootless -noreset -accessx -core -auth/run/user/1000/.
  # to pid 7747
  gnome_pid=$(pgrep gnome-shell | xargs -L1 pstree -s -p -T -a | fzf --tac | sed 's/^[[:space:]]*//g' | cut -d " " -f 1 | cut -d "," -f "2")
  echo "Selected pid is $gnome_pid. Process is:"
  ps aux -q "$gnome_pid"

  echo
  echo 'Will attempt to run the following js code with gdb in batch mode:'
  echo "$script"
  echo
  echo 'WARNING: this will attach the gdb debugger to your selected gnome-shell session.'
  echo 'The session will hang until gdb is finished working.'
  echo 'Press enter to continue or ^C to quit this script.'
  echo 'TODO/WARNING: I have no idea how bad code may break this or hang your UI!'
  read

  #This is the only thing doing any real work here
  # *some* explanation http://helgo.net/simon/introspection-tutorial/stepthree.xhtml , mostly sufficient for this though.
  # The code is run on the main thread. You can check by breakpointing on Interpret.
  # TODO ingest discussion notes
  gdb -p "$gnome_pid" -batch -ex "call (void*)gjs_context_eval((void*)gjs_context_get_current(), \"$1\", -1, \"<injected>\", 0, 0)"

  echo 'Check for success (in the default configuration a result of (true, 'true') means we were successful):'
  gdbus call -e -d org.gnome.Shell -o /org/gnome/Shell -m org.gnome.Shell.Eval 'global.context.unsafe_mode'
  }

main() {
  case $1 in
    t) {
      script='global.context.unsafe_mode = true'
      invoke_gdb "$script"
      };;
    f) {
      echo 'Setting global.context.unsafe_mode to false. Note, this is kind of pointless:'
      echo 'If it'\''s already false this is a no-op, if it'\''s true, it'\''s safer to use gdbus.'
      script='global.context.unsafe_mode = false'
      invoke_gdb "$script"
      };;
    toggle) {
      script='global.context.unsafe_mode = ! global.context.unsafe_mode'
      invoke_gdb "$script"
      };;
    *) {
      echo 'Usage: enable_eval.sh (t|f|toggle)'
      };;
  esac
  }

main "$1"