Commits on Apr 15, 2024

1. HP Secure Browser support (nvaccess#16377): Detect & prevent infinite… …

   … loop in iterUIARangeByUnit
   
   Summary of the issue:
   We're experiencing NVDA locking up trying to infinitely split some text
   ranges, for example on www.bat.org when it tries to split the range representing
   "Submit" button into individual characters.
   
   NVDA hangs completely in this scenario and has to be forcibly killed.
   
   If the offending split is attempted, the hang always happens. Secure Browser seems to be provoking this split more,
   but we've also seen that in normal chromium-based browsers when using UIA instead of IAccessible2.
   This could be due to significant timing differences etc, as the virtualized
   browser has higher overhead.
   
   Typical repro scenario involves navigating to www.bat.org then duplicating the tab &
   closing some of the dupes, until NVDA attempts the split and hangs.
   
   Description of user facing changes:
   Detect & prevent the infinite loop so that NVDA remains responsive
   
   Description of development approach:
   This is likely a deficiency in UIA text range implementation on the chromium
   side, as I don't see anything obviously wrong with the algorithm in
   iterRangeByUnit which is doing the split. Rewriting this UIA algorithm in C++
   and running against offending website also hangs, always, in regular
   Google Chrome, Edge, and Secure Browser.
   
   At the cost of extra Compare COM call we can detect that chromium is yielding
   same range infinitely, and therefore detect & shortcircuit the infinite loop
   on the NVDA side.

   Tomasz Wroblewski committed Apr 15, 2024
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