Re: [PATCH] Some distributions ship compilers that include -fPIE in the default specs (Gentoo Hardened)

[address@hidden]

Why not just check if the compiler accepts -fno-PIE and use it?  No
harm done if -fPIE wasn't default, right?

On Tue, Sep 1, 2009 at 4:46 PM, Magnus Granberg<address@hidden> wrote:
> Hi
>
> On Gentoo Hardened we compile with -fPIE in the default specs and
> grub fails to compile.
> This patch check if the compiler use -fPIE in the default specs and add
> -fno-PIE to TARGET_CFLAGS.
>
> --- aclocal.m4.zorry    2008-02-03 14:11:28.000000000 +0100
> +++ aclocal.m4  2009-08-22 01:05:56.000000000 +0200
> @@ -362,3 +362,31 @@
>   AC_MSG_RESULT([no])
>  [fi]
>  ])
> +
> +dnl Check if the C compiler supports `-fPIE'.
> +AC_DEFUN(grub_CHECK_PIE,[
> +[# Position independent executable.
> +pie_possible=yes]
> +AC_MSG_CHECKING([whether `$CC' has `-fPIE' as default])
> +# Is this a reliable test case?
> +AC_LANG_CONFTEST([[
> +#ifdef __PIE__
> +int main() {
> +       return 0;
> +}
> +#else
> +#error NO __PIE__ DEFINED
> +#endif
> +]])
> +
> +[# `$CC -c -o ...' might not be portable.  But, oh, well...  Is calling
> +# `ac_compile' like this correct, after all?
> +if eval "$ac_compile -S -o conftest.s" 2> /dev/null; then]
> +  AC_MSG_RESULT([yes])
> +  [# Should we clear up other files as well, having called 
> `AC_LANG_CONFTEST'?
> +  rm -f conftest.s
> +else
> +  pie_possible=no]
> +  AC_MSG_RESULT([no])
> +[fi]
> +])
> --- configure.ac.zorry  2008-02-03 14:41:51.000000000 +0100
> +++ configure.ac        2009-09-01 01:05:34.000000000 +0200
> @@ -251,6 +251,14 @@
>  # Compiler features.
>  #
>
> +# Position independent executable.
> +grub_CHECK_PIE
> +[# Need that, because some distributions ship compilers that include
> +# `-fPIE' in the default specs.
> +if [ x"$pie_possible" = xyes ]; then
> +  TARGET_CFLAGS="$TARGET_CFLAGS -fno-PIE"
> +fi]
> +
>  # Smashing stack protector.
>  grub_CHECK_STACK_PROTECTOR
>  [# Need that, because some distributions ship compilers that include
>
> ---
> Hardened-Development Overlay
> Magnus Granberg (Zorry) <address@hidden>
>
>
>
>
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