Add option to wait for GUI session

archlinux/PKGBUILD.in

@@ -7,7 +7,7 @@ pkgdesc="The Qubes service for proxying input devices"
 arch=("x86_64")
 url="http://qubes-os.org/"
 license=('GPL')
-depends=(sh usbutils qubes-vm-core)
+depends=(sh usbutils qubes-vm-core python-pyinotify)
 _pkgnvr="${pkgname}-${pkgver}-${pkgrel}"
 source=("${_pkgnvr}.tar.gz")
 sha256sums=(SKIP)

debian/control

@@ -9,6 +9,7 @@ Homepage:  http://www.qubes-os.org
 Package: qubes-input-proxy-sender
 Architecture: any
 Depends: ${shlibs:Depends}, qubes-core-agent(>=3.0.25)
+Recommends: python3-pyinotify
 Description: Provides Simple input events proxy
  This package is intended to run in a qube with physical input device attached
  (for example USB VM). It sends events to a listener in dom0 which passes

qubes-rpc/qubes-input-trigger

@@ -7,7 +7,66 @@ import argparse
 import subprocess
 import os
 import sys
+import time
 from stat import *
+try:
+    import pyinotify
+    has_inotify = True
+except ImportError:
+    has_inotify = False
+
+
+GUI_STATUS_FILE_PATH = "/run/qubes/gui-agent.status"
+
+
+def wait_for_gui_session():
+    """Wait for user session in GUI domain to initialize. This is relevant for
+        potential qrexec policy prompt ('ask' action) - before GUI session is
+        started, policy prompt cannot be displayed and the call would be
+        denied."""
+
+    if not os.path.exists(GUI_STATUS_FILE_PATH):
+        print(f"{GUI_STATUS_FILE_PATH} does not exist, not waiting for GUI", file=sys.stderr)
+        return
+
+    if has_inotify:
+        wm = pyinotify.WatchManager()
+
+        class EventHandler(pyinotify.ProcessEvent):
+            def __init__(self, *args, **kwargs):
+                super().__init__(*args, **kwargs)
+                self.connected = False
+
+            def check_status_file(self):
+                with open(GUI_STATUS_FILE_PATH) as f:
+                    status = f.read()
+                    if status.strip() == "connected":
+                        self.connected = True
+
+            def process_IN_CLOSE_WRITE(self, event):
+                self.check_status_file()
+
+        handler = EventHandler()
+        notifier = pyinotify.Notifier(wm, handler)
+
+        mask = pyinotify.IN_CLOSE_WRITE  # watched events
+        wdd = wm.add_watch(GUI_STATUS_FILE_PATH, mask)
+
+        handler.check_status_file()
+        notifier.process_events()
+        while not handler.connected and notifier.check_events():
+            notifier.read_events()
+            notifier.process_events()
+    else:
+        connected = False
+        while True:
+            with open(GUI_STATUS_FILE_PATH) as f:
+                status = f.read()
+                if status.strip() == "connected":
+                    break
+
+            time.sleep(1)
+
 
 
 def get_args():
@@ -25,6 +84,12 @@ def get_args():
         "--event",
         required=False
     )
+    parser.add_argument(
+        "--wait-for-gui",
+        required=False,
+        action="store_true",
+        help="Wait for GUI daemon to connect, for user to see qrexec prompt"
+    )
     parser.add_argument(
         "--dom0",
         required=False,
@@ -166,6 +231,9 @@ def main():
     if args.event and not args.action:
         print("Please provide action to perform: add/remove")
 
+    if args.wait_for_gui:
+        wait_for_gui_session()
+
     if args.all:
         handle_all_events(args.dom0)
     else:

qubes-rpc/qubes-input-trigger.desktop

@@ -2,4 +2,4 @@
 Version=1.0
 Type=Application
 Name=Retry Qubes RPC prompts for input devices
-Exec=/usr/bin/qubes-input-trigger --all
+Exec=/usr/bin/qubes-input-trigger --all --wait-for-gui

rpm_spec/input-proxy.spec.in

@@ -32,6 +32,7 @@ This package is receiver part.
 Summary:    Simple input device proxy (sender)
 %{?systemd_requires}
 BuildRequires:  systemd
+Recommends:  python3-inotify
 
 %description sender
 Simple input device proxy, which pass events from /dev/input/eventN device, to