Re: [Texmacs-dev] graphviz plugin broken?

[Martin Costabel]

Joris van der Hoeven wrote:

> Happy new year to everybody!

Same to you!

> > I built TeXmacs-1.0.2.5 on FreeBSD 5.2-i386-RC2, with graphviz-1.10 and
> > found similar behavior, a crash during a graphviz session. TeXmacs has
> > no trouble displaying other postscript images (for example, the gnu head
> > on the welcome page is rendered correctly). On OS X, TeXmacs was also
> > able to render other postscript images.
>
>
> And if you try to load the postscript generated by Graphviz as an image?

I did some tests (I have the same problem as Gregory, with 
texmacs-1.0.2.11 and graphviz-1.9 from Fink). It seems that ghostscript 
crashes, because the postscript output of tm_graphviz is systematically 
truncated at 1024 bytes.

The problem lies in this kind of dynamic buffering of the output of 
popen in the readfile() function. I don't know how realloc() works in 
Linux, but in Darwin, it makes the buffer jump around, i.e. after the 
first realloc, wbuf and buf are no longer pointing to the same place, in 
general, and disaster follows.

I made a test where I just malloc 1024*1000+1 instead of 1025 and 
fread() also 1024*1000 bytes, which should be sufficient for most cases 
(for "graph test {a}", the ps output is about 5KB long, so 1MB should go 
a long way). In this case, the realloc is not launched at all, and the 
result is that the graphviz shell seems to work correctly (Not speaking 
any graphviz, I cannot really test it, but the previously observed 
crashes are absent).

--
Martin