[Buildroot] [PATCH] libselinux: add patch to create a proper pkg-config file

[Thomas Petazzoni]

Hello,

On Wed,  3 Jan 2018 22:08:51 +0100, Marcus Folkesson wrote:
> `includedir` in libselinux.pc is set to $(PREFIX)/include if
> not specified. This result in an incorrect include path when using
> pkg-config.
> 
> Output from `pkg-config -cflags libselinux` without this patch:
> -I/home/marcus/git/buildroot-ostree/output/host/bin/../mips64el-buildroot-linux-gnu/sysroot/home/marcus/git/buildroot-ostree/output/host/mips64el-buildroot-linux-gnu/sysroot/usr/include
> -I/home/marcus/git/buildroot-ostree/output/host/bin/../mips64el-buildroot-linux-gnu/sysroot/usr/include
> 
> Output from `pkg-config -cflags libselinux` with this patch:
> -I/home/marcus/git/buildroot-ostree/output/host/bin/../mips64el-buildroot-linux-gnu/sysroot/usr/include
> 
> This is normally not an issue unless the depending package is compiled
> with `-Werror=missing-include-dirs` as it will be treated as an error.
> 
> Fixes:
> http://autobuild.buildroot.net/results/680458dc049d2c286918aeed745515894f8fcefa/
> 
> Signed-off-by: Marcus Folkesson <marcus.folkesson at gmail.com>

Indeed, the .pc file currently installed is bogus.

> diff --git a/package/libselinux/0004-libselinux-introduce-PCPREFIX-substitute-variables-f.patch b/package/libselinux/0004-libselinux-introduce-PCPREFIX-substitute-variables-f.patch
> new file mode 100644
> index 0000000000..978d0591f3
> --- /dev/null
> +++ b/package/libselinux/0004-libselinux-introduce-PCPREFIX-substitute-variables-f.patch
> @@ -0,0 +1,38 @@
> +libselinux: introduce PCPREFIX substitute variable for .pc files
> +
> +`prefix` in the .pc file may be messed up when using a buildsystem
> +that has specified a sysroot as DESTDIR.
> +We need to make it possible to override the default `libdir`
> +and `includedir`.
> +
> +`includedir` may be overridden by `INCLUDEDIR` but `libdir` is using
> +`PREFIX` to setup the path.
> +
> +Therefore, introduce PCPREFIX to make it possible to generate a more
> +customized .pc file.
> +
> +Signed-off-by: Marcus Folkesson <marcus.folkesson at gmail.com>
> +
> +--- libselinux.orig/src/Makefile	2018-01-03 21:44:49.548561421 +0100
> ++++ libselinux/src/Makefile	2018-01-03 21:44:35.581894904 +0100
> +@@ -9,9 +9,10 @@
> + 
> + # Installation directories.
> + PREFIX ?= $(DESTDIR)/usr
> ++PCPREFIX ?= $(DESTDIR)/usr
> + LIBDIR ?= $(PREFIX)/lib
> + SHLIBDIR ?= $(DESTDIR)/lib
> +-INCLUDEDIR ?= $(PREFIX)/include
> ++INCLUDEDIR ?= $(PCPREFIX)/include

Meh, this is messy :-/

Can we instead switch to using the correct semantic for DESTDIR and
PREFIX ? I.e:

 - PREFIX defines where the program/library will be installed when
   executed.

 - DESTDIR is only passed at installation, to divert the installation
   to a specific folder.

I.e, for the target version, PREFIX=/usr DESTDIR=$(TARGET_DIR), and for
the host version, PREFIX=$(HOST_DIR).

Using this correct semantic would be a lot more readable. Indeed, with
your solution, one wonders why PCPREFIX is used for INCLUDEDIR but not
LIBDIR.

Could you have a look into this ?

Thomas
-- 
Thomas Petazzoni, CTO, Free Electrons
Embedded Linux and Kernel engineering
http://free-electrons.com