[tor-bugs] #31567 [Applications/Tor Browser]: NS_tsnprintf() does not handle %s correctly on Windows

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#31567: NS_tsnprintf() does not handle %s correctly on Windows
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 Reporter:  mcs                                  |          Owner:  gk
     Type:  defect                               |         Status:
                                                 |  needs_revision
 Priority:  Very High                            |      Milestone:
Component:  Applications/Tor Browser             |        Version:
 Severity:  Critical                             |     Resolution:
 Keywords:  ff68-esr, tbb-9.0-must-alpha,        |  Actual Points:
  TorBrowserTeam201908                           |
Parent ID:                                       |         Points:
 Reviewer:                                       |        Sponsor:
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Comment (by pospeselr):

 copied from the mozilla bug:

 So I'm tentatively going to claim this is a bug in mingw's implementation
 of _vsnwprintf in ucrt__vsnwprintf.c. I wrote a quick test program and
 built with msvc 19.21 and verified in windbg that a value of '5' (which
 corresponds to UCRTBASE_PRINTF_LEGACY_VSPRINTF_NULL_TERMINATION |
 UCRTBASE_PRINTF_LEGACY_WIDE_SPECIFIERS ) while mingw's implementation only
 passes in '1' ( UCRTBASE_PRINTF_LEGACY_VSPRINTF_NULL_TERMINATION ).
 Swapping the 5 to a 1 in the debugger gives us the same broken behavior.

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/31567#comment:15>
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