[tex-live] Re: [tex-implementors] Re: bug in etex

[Jonathan Kew]

On 13 Jul 2004, at 1:53 pm, Taco Hoekwater wrote:

>
> Hi all (especially Peter),
>
>> Hi Taco (since i think that you qualify for sorting this out -) and 
>> others,
>>
>> Etex can have > 256 token registers. The following fails (bombs) on 
>> my machine
>> (i cannot make atest file since it's part of a more complex piece of 
>> code)
>> ....
>
> I've been working on this for quite a few hours now, and there really 
> is a bug
> somewhere in the (web2c version of) the etex code. The following 
> extended
> mode plain input file causes both of pdfetex and etex (Web2c 7.5.3 and 
> 7.4.5)
> to quit with SIGSEGV under linux:
>
> ------
>   \toksdef\whatevertoks = 266
>   \toksdef\extratoks = 267
>   \whatevertoks={junk}
>   \everypar{\extratoks=\whatevertoks}
>   \immediate\write16{t={\the\toks265}}
>   some paragraph\par
>   \bye
> -------

FWIW, you might like to know that on my Mac OS X system, I see a crash 
with [pdf]etex, but my current build of XeTeX (a Mac OS X-only 
extension based on e-TeX) does not show the same problem, at least not 
with this particular test case.

Thus,
----
[Kew-TiBook:~] jonathan% etex crash
This is e-TeXk, Version 3.141592-2.1 (Web2C 7.5.2)
  %&-line parsing enabled.
  (/usr/local/teTeX/share/texmf.tetex/web2c/cp8bit.tcx)
entering extended mode
(./crash.tex
t={}
Segmentation fault
[Kew-TiBook:~] jonathan%
----

but,
----
[Kew-TiBook:~] jonathan% xetex crash
This is XeTeXk, Version 3.14159-2.1-0.83 (Web2C 7.5.2)
  %&-line parsing enabled.
entering extended mode
(./crash.tex
t={}
[1] )
Output written on crash.pdf (1 page).
Transcript written on crash.log.
[Kew-TiBook:~] jonathan%
----

I notice that the etex I have installed is 3.141592-2.1, whereas xetex 
is currently based on the sources for 3.14159-2.1. So this raises the 
question in my mind as to whether something in the most recent TeX 
changes is leading to the problem. Note also that the Web2C version is 
the same in both cases.

Of course, it's possible that XeTeX happens to survive this test for 
some other reason. But if anyone has an older build of e-TeX around it 
might be interesting to compare that.

Jonathan