[tor-bugs] #26514 [Applications/Tor Browser]: intermittent updater failures on Win64 (Error 19)

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#26514: intermittent updater failures on Win64 (Error 19)
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 Reporter:  mcs                       |          Owner:  tbb-team
     Type:  defect                    |         Status:  new
 Priority:  Very High                 |      Milestone:
Component:  Applications/Tor Browser  |        Version:
 Severity:  Normal                    |     Resolution:
 Keywords:  TorBrowserTeam201808      |  Actual Points:
Parent ID:                            |         Points:
 Reviewer:                            |        Sponsor:
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Comment (by jacek):

 libmar uses in fact _ftelli64/_fseeki64 due to defines in mar_private.h.
 Those are not available on old msvcrt.dll, so mingw-w64 has its own
 implementation:
 https://github.com/mirror/mingw-w64/blob/master/mingw-w64-crt/stdio/fseeko64.c#L133
 I can't see anything obviously wrong there, but in general it does a lot
 of stuff that really should be done by MS crt in fact. An ideal solution
 would be to use ucrt-based toolchain (ucrtbase.dll always provides those
 functions) and disable mingw-w64 implementation for them. I may take a
 look at mingw-w64 part of it, but changing to ucrt toolchain is an
 invasive change for Tor build system.

 As a less radical solution could be using fseek64 and ftello64. Those are
 much thinner wrappers in mingw-64 around msvcrt.dll. You could try that by
 changing defines in mar_private.h

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Ticket URL: <https://trac.torproject.org/projects/tor/ticket/26514#comment:19>
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