From f74a706adb28f453c6daa59cad1fe2b3e25a672e Mon Sep 17 00:00:00 2001
From: Luca Toniolo <10792599+grandixximo@users.noreply.github.com>
Date: Sat, 30 May 2026 09:38:20 +0800
Subject: [PATCH] gmoccapy: exit cleanly on termination signal instead of error
 dialog

gmoccapy did not exit on SIGTERM; callers had to escalate to SIGKILL.

Root cause: PyGObject's signal bridge surfaces a termination signal into
the GTK main loop as a Python KeyboardInterrupt. That propagated to the
installed sys.excepthook, which unconditionally popped a modal
'Found an error ... KeyboardInterrupt' dialog and blocked in the dialog's
nested loop, so the process never quit.

Handle KeyboardInterrupt at the top of excepthook: log it and quit the
main loop instead of showing the modal error dialog. Verified that
gmoccapy now exits cleanly on SIGTERM (no SIGKILL escalation, no spurious
error-dialog traceback). The previous broken 'except KeyboardInterrupt'
on the window lookup (which could never fire there) is removed.

Surfaced by the ui-smoke tests (PR #4054).

Fixes #4069
---
 src/emc/usr_intf/gmoccapy/gmoccapy.py | 14 ++++++++++++--
 1 file changed, 12 insertions(+), 2 deletions(-)

diff --git a/src/emc/usr_intf/gmoccapy/gmoccapy.py b/src/emc/usr_intf/gmoccapy/gmoccapy.py
index f419ea39b46..86c2ed28a5d 100644
--- a/src/emc/usr_intf/gmoccapy/gmoccapy.py
+++ b/src/emc/usr_intf/gmoccapy/gmoccapy.py
@@ -51,10 +51,20 @@
 
 # Throws up a dialog with debug info when an error is encountered
 def excepthook(exc_type, exc_obj, exc_tb):
+    # A KeyboardInterrupt reaching the excepthook is a termination request:
+    # either SIGINT, or SIGTERM surfaced into the main loop by PyGObject's
+    # signal bridge. Quit cleanly instead of popping a modal error dialog,
+    # which would block in a nested loop and leave gmoccapy running until the
+    # caller escalates to SIGKILL.
+    if issubclass(exc_type, KeyboardInterrupt):
+        LOG.info("gmoccapy interrupted (signal), shutting down")
+        try:
+            Gtk.main_quit()
+        except Exception:
+            pass
+        return
     try:
         w = app.widgets.window1
-    except KeyboardInterrupt:
-        sys.exit()
     except NameError:
         w = None
     lines = traceback.format_exception(exc_type, exc_obj, exc_tb)