Link to issue number:

Fixes #19216
Follow-up #19175

Summary of the issue:

NVDA was failing to start on secure screens, unless the serviceDebug global parameter was set.

Description of user facing changes:

NVDA works on secure desktops again.

Description of developer facing changes:

None

Description of development approach:

The issue was caused by utils._crashHandler.CrashStats.crashStatsPath assuming that globalVars.appArgs.logFileName would always represent a path. Notwithstanding this, it also wrote to disk, even when NVDAState.shouldWriteToDisk returned False (i.e. in scure mode or running from the launcher).

1. Added several defensive measures to the new utils._crashHandler module.
2. Changed watchdog.initialize to no longer add utils._crashHandler.crashHandler as an unhandled exception filter when running in secure mode.

Testing strategy:

Ran from source, and executed the following in the python console to ensure automatic restarts on crash still work as expected:

import ctypes;ctypes.windll.kernel32.DebugBreak()

Modified NVDA to allow the scratchpad in secure mode, built a self-signed launcher, and installed it.

Hit alt+control+delete, and observed that NVDA worked as expected.

Added the following global plugin to the scratchpad of the user and system config:

from globalPluginHandler import GlobalPlugin
import ctypes
from tones import beep
from core import postNvdaStartup

class GlobalPlugin(GlobalPlugin):
	def __init__(self):
		super().__init__()
		postNvdaStartup.register(self.crash)

	def crash(self):
		beep(500,100)
		ctypes.windll.kernel32.DebugBreak()

Restarted NVDA, and observed that it started, a tone was heard, and it crashed, and this only happened 4 times.

Hit alt+control+delete, and observed that NVDA started, a tone was heard, NVDA crashed, and did not restart.

Known issues with pull request:

When NVDA crashes on the secure desktop, no feedback is given to the user. However, this is not new.

Code Review Checklist:

• Documentation:
  • Change log entry
  • User Documentation
  • Developer / Technical Documentation
  • Context sensitive help for GUI changes
• Testing:
  • Unit tests
  • System (end to end) tests
  • Manual testing
• UX of all users considered:
  • Speech
  • Braille
  • Low Vision
  • Different web browsers
  • Localization in other languages / culture than English
• API is compatible with existing add-ons.
• Security precautions taken.