[PATCH] Add valgrind smoke test

[Florian Weimer]

* Joseph Myers:

> On Mon, 24 May 2021, Carlos O'Donell via Libc-alpha wrote:
>
>> > +# Run smoke tests with valgrind to verify dynamic loader
>> > +ifneq ($(VALGRIND),false)
>> > +tests-special += $(objpfx)valgrind-smoke-test.out
>> > +$(objpfx)valgrind-smoke-test.out: $(objpfx)ld.so
>> > +	$(common-objpfx)testrun.sh --tool=valgrind-test /usr/bin/true > $@
>> > +	$(common-objpfx)testrun.sh --tool=valgrind-test /usr/bin/true --help >> $@
>> > +endif
>> Does this work for cross-compiling?
>> 
>> Do you correctly detect the target valgrind and does the test wrapper 
>> allow the correct execution of valgrind on the target system?
>
> My expectation is that <host>-valgrind won't exist - but AC_CHECK_TOOL is 
> documented as falling back to the tool without a host prefix if a prefixed 
> version doesn't exist, which is a problem.  Logically, this test should 
> run if valgrind is available on the test system (which would need to be 
> determined when the tests are run, test-wrapper isn't available when glibc 
> is built), but the test-wrapper interface doesn't strictly support running 
> arbitrary installed programs like that.  So you might need a test program 
> (run on the test system via test-wrapper) that itself checks for valgrind 
> being available in the PATH and runs it or returns UNSUPPORTED if not 
> available.  That is, something like nptl/tst-pthread-gdb-attach.c, which 
> handles checking for whether gdb is available.

Would it be okay to run these tests only if $(run-built-tests) is yes,
$(cross-compiling) is no, and configure had found a valgrind binary?

I think even a minimal test which is does not work for cross-compilation
would be valuable.

Thanks,
Florian