[texhax] tex filename backtrace utility

[Karl Berry]

Sometimes it would be helpful for tex debugging to get a "backtrace" of
the files that tex is executing.  It could be something static, that
reads a .log file (or maybe .fls file from -recorder) and reports on
which files were opened and closed in some way that is readable for deep
nesting.

I seem to recall that auctex and presumably front ends have dealt with
extracting the filenames, at least, out of the mess of garbage printed
to the terminal on a typical run, parsing all the open/close parens, but
I've been unable to find anything that works as a separate utility.

Does anyone know of something to do this?

Failing anything else, I wonder about adding a new primitive to pdftex
to dump the input stack at any point.  Then we could get line numbers
too, I expect.

Thanks,
Karl