qtvcp: exit cleanly on SIGTERM/SIGINT#4078
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c-morley merged 1 commit intoMay 30, 2026
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qtvcp registered self.shutdown as the SIGTERM/SIGINT handler, but two things stopped it working: Qt's C++ event loop (APP.exec()) does not return to Python often enough to run Python signal handlers, and shutdown() cleans up without quitting the loop, so even when reached the process kept running. A caller tearing qtvcp down therefore had to escalate to SIGKILL. Quit the event loop on the signal (APP.quit()) so APP.exec() returns and the existing post-exec shutdown() runs the normal cleanup once, and add a periodic no-op QTimer so the interpreter gets a chance to run the signal handler during exec(). Quitting the loop bypasses the window-close confirmation dialog, which is correct for a terminate request and leaves that interactive feature untouched. Fixes the hang for all qtvcp screens (qtdragon, qtplasmac, ...). Verified qtdragon exits cleanly on SIGTERM and SIGINT. Surfaced by the ui-smoke tests (PR LinuxCNC#4054).
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Adds a quit-path smoke test per GUI that boots the GUI, waits for the NML task to come up, sends SIGTERM to the GUI process alone, and asserts the GUI exits on its own within a short grace. This guards the clean-shutdown handlers: a GUI that absorbs SIGTERM and has to be SIGKILLed fails the test. The new _lib/quit-launch.sh shares the headless environment (software GL + audio silencing) with launch.sh by sourcing a new _lib/launch-env.sh rather than copying it, so the two launchers cannot drift apart. Results go through _lib/checkresult-quit.sh (pass on UI_SMOKE_QUIT_OK). The GUI process is identified by matching a python argv[0], so the linuxcnc launcher and xvfb-run wrappers that also carry the GUI name on their command line are not mistaken for it. Per-GUI dirs: touchy-quit, gmoccapy-quit, qtdragon-quit. The qtdragon quit test needs the same CI workarounds the qtdragon smoke test already carries (writable config mirror with a patched LOG_FILE, the offscreen Qt platform, and the QtWebEngine import shim). Those move out of qtdragon/test.sh into _lib/qtdragon-prepare.sh, sourced by both qtdragon test.sh files, so the quit test reuses them instead of leaving qtvcp to crash on startup. Requires the SIGTERM handlers in LinuxCNC#4076 (gmoccapy), LinuxCNC#4077 (touchy) and LinuxCNC#4078 (qtvcp); without them the GUIs ignore SIGTERM and these tests fail by design.
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qtvcp screens (qtdragon etc.) ignored SIGTERM and SIGINT: Python signal handlers do not run while
QApplication.exec()blocks in the Qt C++ loop, so the process never exited and ui-smoke teardown escalated to SIGKILL.This quits the Qt loop directly on SIGTERM and SIGINT, and adds a low-frequency
QTimerso the interpreter periodically regains control to deliver the signal. The existing post-execshutdown()still runs the cleanup. The X-button "are you sure?" confirmation dialog is left intact for interactive close; only the terminate signals bypass it, which is correct for SIGTERM.Part of the SIGTERM clean-shutdown work discussed in #4054.