1 files changed, 89 insertions, 0 deletions
diff --git a/nixos/modules/services/x11/display-managers/set-session.py b/nixos/modules/services/x11/display-managers/set-session.py
new file mode 100755
index 00000000000..75940efe32b
--- /dev/null
+++ b/nixos/modules/services/x11/display-managers/set-session.py
@@ -0,0 +1,89 @@
+#!/usr/bin/env python
+
+import gi, argparse, os, logging, sys
+
+gi.require_version("AccountsService", "1.0")
+from gi.repository import AccountsService, GLib
+from ordered_set import OrderedSet
+
+
+def get_session_file(session):
+    system_data_dirs = GLib.get_system_data_dirs()
+
+    session_dirs = OrderedSet(
+        os.path.join(data_dir, session)
+        for data_dir in system_data_dirs
+        for session in {"wayland-sessions", "xsessions"}
+    )
+
+    session_files = OrderedSet(
+        os.path.join(dir, session + ".desktop")
+        for dir in session_dirs
+        if os.path.exists(os.path.join(dir, session + ".desktop"))
+    )
+
+    # Deal with duplicate wayland-sessions and xsessions.
+    # Needed for the situation in gnome-session, where there's
+    # a xsession named the same as a wayland session.
+    if any(map(is_session_wayland, session_files)):
+        session_files = OrderedSet(
+            session for session in session_files if is_session_wayland(session)
+        )
+    else:
+        session_files = OrderedSet(
+            session for session in session_files if is_session_xsession(session)
+        )
+
+    if len(session_files) == 0:
+        logging.warning("No session files are found.")
+        sys.exit(0)
+    else:
+        return session_files[0]
+
+
+def is_session_xsession(session_file):
+    return "/xsessions/" in session_file
+
+
+def is_session_wayland(session_file):
+    return "/wayland-sessions/" in session_file
+
+
+def main():
+    parser = argparse.ArgumentParser(
+        description="Set session type for all normal users."
+    )
+    parser.add_argument("session", help="Name of session to set.")
+
+    args = parser.parse_args()
+
+    session = getattr(args, "session")
+    session_file = get_session_file(session)
+
+    user_manager = AccountsService.UserManager.get_default()
+    users = user_manager.list_users()
+
+    for user in users:
+        if user.is_system_account():
+            continue
+        else:
+            if is_session_wayland(session_file):
+                logging.debug(
+                    f"Setting session name: {session}, as we found the existing wayland-session: {session_file}"
+                )
+                user.set_session(session)
+                user.set_session_type("wayland")
+            elif is_session_xsession(session_file):
+                logging.debug(
+                    f"Setting session name: {session}, as we found the existing xsession: {session_file}"
+                )
+                user.set_x_session(session)
+                user.set_session(session)
+                user.set_session_type("x11")
+            else:
+                logging.error(f"Couldn't figure out session type for {session_file}")
+                sys.exit(1)
+
+
+if __name__ == "__main__":
+    main()