[Buildroot] [PATCH 5/6] core: check host executables have appropriate RPATH
Peter Korsgaard
peter at korsgaard.com
Wed Nov 18 21:46:16 UTC 2015
>>>>> "Yann" == Yann E MORIN <yann.morin.1998 at free.fr> writes:
> When we build our host programs, and they depend on a host library we
> also build, we want to ensure that program actually uses that library at
> runtime, and not the one from the system.
> We currently ensure that in two ways:
> - we add a RPATH tag that points to our host library directory,
> - we export LD_LIBRARY_PATH to point to that same directory.
> With thse two in place, we're pretty much confident that our host
> libraries will be used by our host programs.
> However, it turns our that not all the host programs we build end up
> with an RPATH tag:
> - some packages do not use our $(HOST_LDFLAGS)
> - some packages' build system are oblivious to those LDFLAGS
> In this case, there are two situation:
> - the program is not linked to one of our host libraries: it in fact
> does not need an RPATH tag [0]
> - the program actually uses one of our host libraries: in that case it
> should have had an RPATH tag pointing to the host directory.
> As for libraries, it is unclear whether they should or should not have
> an RPATH pointing to our host directory. as for programs, it is only
> important they have such an RPATH if they have a dependency on another
> host lbrary we build. But even though, in practice this is not an issue,
> because the program that loads such a libray does have an RPATH (it did
> find that library!), so the RPATH from the program is also used to
> search for second-level (and third-level...) dependencies, as well as
> for libraries loaded via dlopen().
> We add a new support script that checks that all ELF executables have
> a proper DT_RPATH (or DT_RUNPATH) tag when they link to our host
> libraries, and reports those file that are missing an RPATH. If a file
> missing an RPATH is an executable, the script aborts; if only libraries
> are are missing an RPATH, the script does not abort.
> [0] Except if it were to dlopen() it, of course, but the only program
> I'm aware of that does that is openssl, and it has a correct RPATH tag.
> Signed-off-by: "Yann E. MORIN" <yann.morin.1998 at free.fr>
> Cc: Thomas Petazzoni <thomas.petazzoni at free-electrons.com>
> Cc: Arnout Vandecappelle <arnout at mind.be>
> Cc: Peter Korsgaard <jacmet at uclibc.org>
Committed, thanks.
--
Bye, Peter Korsgaard
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