[Buildroot] [PATCH 3/5 v2] toolchain: check the SSP option is known

[yann.morin at orange.com]

Thomas, All,

On 2019-03-26 20:26 +0100, Thomas Petazzoni spake thusly:
> On Tue, 12 Mar 2019 13:09:34 +0100
> <yann.morin at orange.com> wrote:
> 
> >  # $1: cross-gcc path
> > +# $2: gcc ssp option
> >  #
> >  check_toolchain_ssp = \
> >  	__CROSS_CC=$(strip $1) ; \
> > @@ -427,6 +428,13 @@ check_toolchain_ssp = \
> >  		echo "SSP support not available in this toolchain, please disable BR2_TOOLCHAIN_EXTERNAL_HAS_SSP" ; \
> >  		exit 1 ; \
> >  	fi ; \
> > +	__SSP_OPTION=$(2); \
> > +	if [ -n "$${__SSP_OPTION}" ] ; then \
> > +		if ! echo 'void main(){}' | $${__CROSS_CC} -Werror $${__SSP_OPTION} -x c - -o $(BUILD_DIR)/.br-toolchain-test.tmp >/dev/null 2>&1 ; then \
> > +			echo "SSP option $${__SSP_OPTION} not available in this toolchain, please select another SSP level" ; \
> > +			exit 1 ; \
> > +		fi; \
> > +	fi; \
> 
> Does it really make sense to check for both -fstack-protector (in the
> code that already exists) *and* BR2_SSP_OPTION ?
> 
> Wouldn't it make more sense to just check for BR2_SSP_OPTION ?

My reasoning behind this additional test, is that there are two things
we need to test:

  * does the toolchain have SSP support (or not) as claimed by the user?

  * does the toolchain actually support the SSP level requested by the
    user?

There are packages that, wrongly or rightfully so, are not concerned
with te SSP level, but just the fact that there is SSP or not.

So, I decided to keep the existing test, and expand it. It means that we
may indeed check for -fstack-protector twice.

Regards,
Yann E. MORIN.

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