hst: expose scheduling policy

This is primarily useful for poorly written music players for now.

Signed-off-by: Ophestra <cat@gensokyo.uk>

test/configuration.nix

@@ -28,6 +28,15 @@
   # Automatically login on tty1 as a normal user:
   services.getty.autologinUser = "alice";
 
+  security.pam.loginLimits = [
+    {
+      domain = "@users";
+      item = "rtprio";
+      type = "-";
+      value = 1;
+    }
+  ];
+
   environment = {
     systemPackages = with pkgs; [
       # For D-Bus tests:

test/interactive/configuration.nix

@@ -23,6 +23,14 @@
   security = {
     sudo.wheelNeedsPassword = false;
     rtkit.enable = true;
+    pam.loginLimits = [
+      {
+        domain = "@users";
+        item = "rtprio";
+        type = "-";
+        value = 1;
+      }
+    ];
   };
 
   services = {

test/test.py

@@ -206,6 +206,14 @@ machine.wait_until_fails("pgrep foot", timeout=5)
 machine.wait_for_file("/tmp/shim-cont-unexpected-pid")
 print(machine.succeed('grep "shim: got SIGCONT from unexpected process$" /tmp/shim-cont-unexpected-pid'))
 
+# Check setscheduler:
+sched_unset = int(machine.succeed("sudo -u alice -i hakurei -v run cat /proc/self/sched | grep '^policy' | tr -d ' ' | cut -d ':' -f 2"))
+if sched_unset != 0:
+    raise Exception(f"unexpected unset policy: {sched_unset}")
+sched_idle = int(machine.succeed("sudo -u alice -i hakurei -v run --sched=idle cat /proc/self/sched | grep '^policy' | tr -d ' ' | cut -d ':' -f 2"))
+if sched_idle != 5:
+    raise Exception(f"unexpected idle policy: {sched_idle}")
+
 # Start app (foot) with Wayland enablement:
 swaymsg("exec ne-foot")
 wait_for_window(f"u0_a{hakurei_identity(0)}@machine")