[dvipdfmx] Intermittent xdvipdfmx failure

[Tim Eyre]

I recently upgraded to TeXLive 2020 on Windows 10. I recently noticed that
documents that compiled OK under TeXLive 2013 were intermittently failing
under TeXLive 2020. In the failure cases, XeTeX only partially generated
the PDF file.

Investigation revealed that xdvipdfmx was intermittently failing when
presented with heavy use of the Batang Korean font, which is a built-in
Windows 10 font. Here is a minimal example:

\font\Korean="Batang" at 10pt
\newcount\CrashCount
\CrashCount=1
\loop\ifnum\CrashCount<4000
    X {\Korean 서울} X
  \advance\CrashCount by1
  \repeat
\bye

It is usually necessary to process a file like this several times to
trigger the failure. Therefore I wrote a batch job to help with diagnosis:

@echo off
xetex -no-pdf test.tex
:LOOPSTART
xdvipdfmx test.xdv
if "%ERRORLEVEL%"=="0" goto LOOPSTART
echo Failed with error %ERRORLEVEL%

The XeTeX log file gives the following error, indicating that xdvipdfmx
crashed on an Access Violation:

Error -1073741819 (driver return code) generating output

In Windows,  -1073741819 = 0xC0000005 =  Access Violation

The version of xdvipdfmx I am using is 20201111.

I have worked around the issue by putting a retry loop around my call out
to xetex in my Python code. Therefore this glitch is not causing me a
problem. However, I feel a duty to report it to the (x)dvipdfmx community
so that someone can fix it if they feel that doing so is the right thing to
do.

Tim
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <https://tug.org/pipermail/dvipdfmx/attachments/20210123/d7d8ff99/attachment.html>