[Buildroot] [PATCH 1/1] ccid: fix build with pkgconf 1.5.3

[Fabrice Fontaine]

Hello,
Le mar. 11 déc. 2018 à 22:57, Arnout Vandecappelle <arnout at mind.be> a écrit :
>
>
>
> On 11/12/2018 19:55, Yann E. MORIN wrote:
> > Arnout, Fabrice,
> >
> > On 2018-12-11 19:21 +0100, Arnout Vandecappelle spake thusly:
> >> On 11/12/2018 18:21, Fabrice Fontaine wrote:
> >>> Do not add DESTDIR before usbdropdir to install pcsc drivers in
> >>> src/Makefile.am.
> >>>
> >>> Indeed, usbdropdir is retrieved from libpcsc.pc and can be prefixed by
> >>> sysroot, so it can can be set for example to:
> >>> usbdropdir='/accts/mlweber1/rclinux/rc-buildroot-test/scripts/instance-3/output/host/bin/../microblazeel-buildroot-linux-uclibc/sysroot/usr/lib/pcsc/drivers'
> >>>
> >>> If DESTDIR is added before usbdropdir, files will be installed in a
> >>> wrong directory and build will fail
> >>
> >>  I have the feeling this is not the right fix. I think the problem really is
> >> that pkg-config should prefix usbdropdir with sysroot. To me it seems that the
> >> right thing to do is to add the sysroot to -L and -I flags, but not to add it to
> >> random variables...
> >>
> >>  Maybe other people who have a better understanding of how pkg-config is
> >> supposed to work can shed some light?
> >
> > Indeed, we must be careful with how we handle pkg-config.
> >
> > For this specific case, I agree with Arnout: installing a file should
> > always be prefixed by DESTDIR. We should not change that part of a
> > package installation.
>
>  Especially because it is *wrong*, because the files will not be installed in
> target...
>
> >
> > There are two conflicting needs: to know where the files are at build
> > time, and to know where they are at runtime.
> >
> > With pkg-config, there is a mix of both concepts, and they are
> > absolutely not differentiated. That's probably because pkg-config was
> > initially made to be able to provide build-time-only files: headers and
> > libs. But packages (ab)used it to also store and share arbitrary
> > variables, and they expect those locations to be valid both at build
> > time and runtime, which is wrong, as we can see in a lot of cases, such
> > as this one...
> >
> > Before we bumped pkg-config, we had a patch that would make it prefix
> > a set of carefully selected variables (instead of just -I and -L). But
> > that was probably goign to be an endless whack-a-mole game, and upstream
> > decided to now prefix all variables (again, instead of only -I and -L).
> >
> > However, I have no good idea on how to solve this situation in a generic
> > way.
>
>  I don't even know how to do it in a specific way :-)
>
>  I poked around a bit in pkgconf sources, and this is the fragment that adds the
> sysroot:
>
>          if (*value == '/' && client->sysroot_dir != NULL && strncmp(value,
> client->sysroot_dir, strlen(client->sysroot_dir)))
>                  bptr += pkgconf_strlcpy(buf, client->sysroot_dir, sizeof buf);
>
>
>  This is done unconditionally as far as I can see...
>
>  So I see a couple of possibilities...
>
> 1. Patch pkgconf to add the sysroot only for a whitelisted set of keys.
>
> 2. Mark the not-to-be-prefixed variables in the .pc file in some way, and
> interpret that mark in pkgconf.
>
> 3. Make sure the value in the .pc file doesn't start with / - since there will
> always be a DESTDIR prefixed to it, we can just make DESTDIR end with /.
>
> 4. Do some argument munging in the pkg-config wrapper script and don't set
> PKG_CONFIG_SYSROOT_DIR if some random variable is requested - probably we
> capture almost all broken cases by just matching --variable= in the argument list.
>
>
>  I can't say I really like any of these solutions though...
An other option would be to ignore the value provided by pkgconfig.
For example, we can pass
--enable-usbdropdir=$(TARGET_DIR)/usr/lib/pcsc/drivers to ccid's
configure.
Would it be acceptable?
>
>  Regards,
>  Arnout
Best Regards,

Fabrice