[tex-live] shell_escape extension patch

[Taco Hoekwater]

Jonathan Kew wrote:
> Could I suggest that rather than changing the pascal/web code of  
> pdftex, you consider doing the implementation in a C function  somewhere 
> such as texmfmp.c, where it can be readily available for  use in pdftex, 
> omega, aleph, xetex (but can be excluded by  conditional compilation for 
> MF, for example).

I would like that, but in the current situation that solution still
needs support from the web2c change file.

Intercepting open_input() and  open_output() is easy, because the web
uses aopenin() and aclosein(), that are #defined in one of the header
files.

But the C function aclose() is called directly from the web
source,  so it cannot be aliased in a header file (and a hook is
required because pipes have to be closed with pclose()).

Taco