[dm-devel] [PATCH] multipath-tools: Makefile.inc: add test for -D_FORTIFY_SOURCE=3

[Benjamin Marzinski]

On Mon, May 09, 2022 at 05:21:27PM +0200, mwilck at suse.com wrote:
> From: Martin Wilck <mwilck at suse.com>

Reviewed-by: Benjamin Marzinski <bmarzins at redhat.com>

> 
> 6186645 ("Fix possibility to redefine -D_FORTIFY_SOURCE macro.")
> does not work as-is, because OPTFLAGS can't be used to override CPPFLAGS.
> Instead, add a test for support of -D_FORTIFY_SOURCE=3, and use it
> automatically if supported. The test uses similar logic as e.g.
> https://sourceware.org/git/?p=elfutils.git;a=commit;h=29859f2e79ef3c650ee9712cae990c6a7f787a7d
> 
> This test works in environments with glibc 2.33 or newer. On older distributions,
> -D_FORTIFY_SOURCE=3 does not cause an error, and will thus be used. In this
> case, it has the same effect as -D_FORTIFY_SOURCE=2. On alpine Linux (musl
> libc), -D_FORTIFY_SOURCE=3 generates an error.
> 
> Fixes: 6186645 ("Fix possibility to redefine -D_FORTIFY_SOURCE macro.")
> Signed-off-by: Martin Wilck <mwilck at suse.com>
> ---
>  Makefile.inc | 16 +++++++++++++++-
>  1 file changed, 15 insertions(+), 1 deletion(-)
> 
> diff --git a/Makefile.inc b/Makefile.inc
> index cef7a06..b915c06 100644
> --- a/Makefile.inc
> +++ b/Makefile.inc
> @@ -117,6 +117,20 @@ TEST_CC_OPTION = $(shell \
>  		echo "$(2)"; \
>  	fi)
>  
> +# "make" on some distros will fail on explicit '#' or '\#' in the program text below
> +__HASH__ := \#
> +# Check if _DFORTIFY_SOURCE=3 is supported.
> +# On some distros (e.g. Debian Buster) it will be falsely reported as supported
> +# but it doesn't seem to make a difference wrt the compilation result.
> +FORTIFY_OPT := $(shell \
> +	if /bin/echo -e '$(__HASH__)include <string.h>\nint main(void) { return 0; }' | \
> +		$(CC) -o /dev/null -c -O2 -Werror -D_FORTIFY_SOURCE=3 -xc - 2>/dev/null; \
> +	then \
> +		echo "-D_FORTIFY_SOURCE=3"; \
> +	else \
> +		echo "-D_FORTIFY_SOURCE=2"; \
> +	fi)
> +
>  STACKPROT := $(call TEST_CC_OPTION,-fstack-protector-strong,-fstack-protector)
>  ERROR_DISCARDED_QUALIFIERS := $(call TEST_CC_OPTION,-Werror=discarded-qualifiers,)
>  WNOCLOBBERED := $(call TEST_CC_OPTION,-Wno-clobbered -Wno-error=clobbered,)
> @@ -126,7 +140,7 @@ OPTFLAGS	:= -O2 -g $(STACKPROT) --param=ssp-buffer-size=4
>  WARNFLAGS	:= -Werror -Wall -Wextra -Wformat=2 $(WFORMATOVERFLOW) -Werror=implicit-int \
>  		  -Werror=implicit-function-declaration -Werror=format-security \
>  		  $(WNOCLOBBERED) -Werror=cast-qual $(ERROR_DISCARDED_QUALIFIERS)
> -CPPFLAGS	:= -D_FORTIFY_SOURCE=2
> +CPPFLAGS	:= $(FORTIFY_OPT)
>  CFLAGS		:= --std=gnu99 $(CFLAGS) $(OPTFLAGS) $(WARNFLAGS) -pipe \
>  		   -DBIN_DIR=\"$(bindir)\" -DMULTIPATH_DIR=\"$(plugindir)\" -DRUN_DIR=\"${RUN}\" \
>  		   -DCONFIG_DIR=\"$(configdir)\" -DEXTRAVERSION=\"$(EXTRAVERSION)\" -MMD -MP
> -- 
> 2.36.0