[aur-general] Merge request: python2-pyside -> python-pyside

[Xyne]

Chris “Kwpolska” Warrick wrote:

>Why not adapt the actual Bash parser (in C) to only read and do stuff
>safely?  In most cases, this would be enough.  In the others, we
>already have mess in those fields in the AUR. (my C skills are not
>appropriate for this)

That is basically what needs to be done but it is a difficult task. Even if you
can adapt the Bash source code to return the AST,  you would still need to
create an extensive whitelist of executables (both internal and external) that
may be run in order interpolate all of the variables. The code must be able to
detect variable settings nested in the package functions, skip commands that do
not affect variables (which may require it to work backwards), count loop
cycles to prevent infinite loops, track time to prevent timeouts, etc.

I have thought about this before when I wrote the Bauerbill PKGBUILD parser,
but I gave up trying to find a way to extract the AST using the Bash code. In
the end my code would simply wrap the PKGBUILD in a function, source the file,
spit it out with "set" to homogenize the syntax, and then parse it with
regexes.

I started writing a Bash parser in Haskell with Parsec but my free time ran out
and I had to move on to other things. I think that approach would work quite
well if the Bash sources are too tangled to extract the parser, but it is a
huge task for one person (word expansion, string manipulation, all of the
built-ins, etc.). I would be willing to collaborate on that as well, if there
is any interest.

Regards,
Xyne