[LTP] [PATCH v4] syscalls/prctl02: add more error tests

[Cyril Hrubis <chrubis@suse.cz>]

Hi!
> > 1) Can undefined error be triggered on old kernel if you use ifdef?  It seems unnecessary for ifdef method to include lapi header.
> 
> Yes. It can be triggered and it should use #if HAVE_DECL_PR_GET_SPECULATION_CTRL instead of #ifdef.
> Yes. And we should add more check( such as PR_SET_SECCOMP undefined 2.6.18-398.el5) in m4/ltp-prctl.m4 so that we cannot include lapi header.
> 
> > 2) Undfined option in glibc doesn't mean that kernel doesn't support it as well.
> 
> options definitions is in linux/prctl.h. For most distributions, I think if it is in supported in kernel-header, it should also been
> supported on kernel.

That is usually the case, but there are cons that I explained in the
previous email.

> >> IMO, we only test options that kernel supports.
> >> If we test an unsupported option, our case reports EINVAL that will give user a false impression(kernel
> >> supports it, but argument or environment is bad). I think we should check they whether supported before run
> >> (ifdef is a way).
> >>
> >> ps: If we test EPERM error(cap is not in PI or PP) of PR_CAP_AMBIENT on old kernel,  they will report EINVAL.
> >> So, I think ifdef is needed.
> > Why don't we check if the specified option is supported by calling it 
> > with correct args?(i.e. don't mix unsupported option up with wrong args).
> >
> It sounds reasonable.  I will try it in verify_prctl function if you and cyril have strong opposition to #if.

Okay, that will work. Calling it with correct parameters in test setup
is 100% correct way how to find out if kernel implements the
functionality.

-- 
Cyril Hrubis
chrubis@suse.cz