Re: gnunet-config and build informations (bug #5708)

[Alessio Vanni]

Hello,

Christian Grothoff <grothoff@gnunet.org> writes:

> GNU Taler has taler-config, which recycles gnunet-config in a funky way
> using LD_PRELOAD:
>
> https://git.taler.net/exchange.git/tree/src/util/taler-config.in
>
> This works, because there is:
> https://git.taler.net/exchange.git/tree/src/util/os_installation.c
>
> which overrides gnunet-config settings to turn it into taler-config!
>
> So _ideally_, we would use the GNUNET_OS_ProjectData instead of directly
> using hard-coded values for the output of the new flags. That way, we
> could modify GNU Taler so that taler-config will not return the GNUnet
> flags, but the Taler flags (again using preload, without copying the
> source!)

I don't follow Taler's development, so I didn't know about this "trick".
Thanks for reporting.

I'm going to push a patch to change the hardcoded values to something
based on the values returned by `GNUNET_OS_installation_get_path'.
Hopefully that's going to work for Taler, as I can't think of any other
way to have it print the includedir and the libdir otherwise :)

As a side note, to keep gnunet-config coherent with the pkg-config
definition, I also had it print `-lgnunetutil' when using the `--libs'
flag.

I don't know how Taler handles its public APIs, if it has any, so if an
application wants to compile against Taler it would be useful to have
taler-config also print e.g. `-ltalerutil'.

I doubt this is something that gnunet-config can handle internally, so
if Taler (or any application using the LD_PRELOAD + gnunet-config combo)
has special needs for the `--libs' (or even the `--cflags') flag, the
execution with that flag should be intercepted somehow and the
appropriate values appended to the default output of gnunet-config.

Thanks,
A.V.