[PATCH 2/4] tests: Fix mock chaining on macOS

[Roman Bolshakov]

On Fri, Nov 13, 2020 at 04:58:39PM +0100, Michal Privoznik wrote:
> On 11/8/20 10:24 PM, Roman Bolshakov wrote:
> > Some tests in qemuxml2argvtest need opendir() from virpcimock, others
> > need opendir() from virfilewrapper.
> > 
> > But as of now, only opendir() from virpcimock has an effect.
> > real_opendir in virpcimock has a pointer to opendir$INODE64 in
> > libsystem_kernel.dylib instead of pointing to opendir$INODE64 in
> > qemuxml2argvtest (from virfilewrapper). And because the second one is
> > never used, tests that rely on prefixes added by virFileWrapperAddPrefix
> > fail.
> > 
> > That can be fixed if dlsym(3) is asked explicitly to search symbols in
> > main executable with RTLD_MAIN_ONLY before going to other dylibs.
> > Existing RTLD_NEXT handle results into libsystem_kernel.dylib being
> > searched before main executable.
> > 
> > Signed-off-by: Roman Bolshakov <r.bolshakov at yadro.com>
> > ---
> >   tests/virmock.h    | 37 +++++++++++++++++++++++++++++++++++--
> >   tests/virpcimock.c |  1 +
> >   2 files changed, 36 insertions(+), 2 deletions(-)
> > 
> > diff --git a/tests/virmock.h b/tests/virmock.h
> > index dea5feb80f..db051f3636 100644
> > --- a/tests/virmock.h
> > +++ b/tests/virmock.h
> > @@ -284,8 +284,19 @@
> >       static void (*real_##name)(void); \
> >       void wrap_##name(void)
> > +#ifdef __APPLE__
> > +# define VIR_MOCK_REAL_INIT_MAIN(name, alias) \
> > +    do { \
> > +        if (real_##name == NULL) { \
> > +            real_##name = dlsym(RTLD_MAIN_ONLY, alias); \
> > +        } \
> > +    } while (0)
> > +#else
> > +# define VIR_MOCK_REAL_INIT_MAIN(name, alias) \
> > +    do {} while (0)
> > +#endif
> > -#define VIR_MOCK_REAL_INIT(name) \
> > +#define VIR_MOCK_REAL_INIT_NEXT(name) \
> >       do { \
> >           if (real_##name == NULL && \
> >               !(real_##name = dlsym(RTLD_NEXT, \
> > @@ -295,7 +306,7 @@
> >           } \
> >       } while (0)
> > -#define VIR_MOCK_REAL_INIT_ALIASED(name, alias) \
> > +#define VIR_MOCK_REAL_INIT_ALIASED_NEXT(name, alias) \
> >       do { \
> >           if (real_##name == NULL && \
> >               !(real_##name = dlsym(RTLD_NEXT, \
> > @@ -304,3 +315,25 @@
> >               abort(); \
> >           } \
> >       } while (0)
> > +
> > +#ifdef VIR_MOCK_LOOKUP_MAIN
> 
> I think we can do this even without this macro. If the VIR_MOCK_LOOKUP_MAIN
> macro is not defined then we are still guarded by VIR_MOCK_REAL_INIT_MAIN()
> being a NOP on !__APPLE__. Also ..


Yeah, that works for me. I thought of it after I sent the patch :)
I'll improve it, thanks!

> 
> > +# define VIR_MOCK_REAL_INIT(name) \
> > +    do { \
> > +        VIR_MOCK_REAL_INIT_MAIN(name, #name); \
> > +        VIR_MOCK_REAL_INIT_NEXT(name); \
> > +    } while (0)
> > +# define VIR_MOCK_REAL_INIT_ALIASED(name, alias) \
> > +    do { \
> > +        VIR_MOCK_REAL_INIT_MAIN(name, alias); \
> > +        VIR_MOCK_REAL_INIT_ALIASED_NEXT(name, alias); \
> > +    } while (0)
> > +#else
> > +# define VIR_MOCK_REAL_INIT(name) \
> > +    do { \
> > +        VIR_MOCK_REAL_INIT_NEXT(name); \
> > +    } while (0)
> > +# define VIR_MOCK_REAL_INIT_ALIASED(name, alias) \
> > +    do { \
> > +        VIR_MOCK_REAL_INIT_ALIASED_NEXT(name, alias); \
> > +    } while (0)
> > +#endif
> > diff --git a/tests/virpcimock.c b/tests/virpcimock.c
> > index 686f894e99..4aa96cae08 100644
> > --- a/tests/virpcimock.c
> > +++ b/tests/virpcimock.c
> > @@ -19,6 +19,7 @@
> >   #include <config.h>
> >   #if defined(__linux__) || defined(__FreeBSD__) || defined(__APPLE__)
> > +# define VIR_MOCK_LOOKUP_MAIN
> 
> .. it feels a bit odd that this is defined for virpcimock only.
> 

That's the only place where exact lookup order is needed.

Regards,
Roman