error: "_FORTIFY_SOURCE" redefined [-Werror]

[stintel]

Host build of ucode fails on my system:

[3/40] /home/stijn/Development/OpenWrt/openwrt/staging_dir/host/bin/gcc -DHAVE_ARRAY_EXT -DHAVE_JSON_UINT64 -DHAVE_PARSE_END -DLIB_SEARCH_PATH="\"/home/stijn/Development/OpenWrt/openwrt/staging_dir/hostpkg/lib/ucode/*.so\", \"/home/stijn/Development/OpenWrt/openwrt/staging_dir/hostpkg/share/ucode/*.uc\", \"./*.so\", \"./*.uc\"" -DNDEBUG -D_FORTIFY_SOURCE=2 -D_GNU_SOURCE -Dlibucode_EXPORTS -I"/home/stijn/Development/OpenWrt/openwrt/build_dir/hostpkg/ucode-2025.02.10~a8a11aea/include" -I/home/stijn/Development/OpenWrt/openwrt/staging_dir/host/include/json-c -O2 -I/home/stijn/Development/OpenWrt/openwrt/staging_dir/host/include -I/home/stijn/Development/OpenWrt/openwrt/staging_dir/hostpkg/include -I/home/stijn/Development/OpenWrt/openwrt/staging_dir/target-aarch64_cortex-a53_musl/host/include -DNDEBUG -fPIC   -Os -Wall -Werror --std=gnu99 -ffunction-sections -fwrapv -Wextra -Werror=implicit-function-declaration -Wformat -Werror=format-security -Werror=format-nonliteral -Wmissing-declarations -Wno-error=unused-variable -Wno-unused-parameter -MD -MT CMakeFiles/libucode.dir/platform.c.o -MF CMakeFiles/libucode.dir/platform.c.o.d -o CMakeFiles/libucode.dir/platform.c.o -c '/home/stijn/Development/OpenWrt/openwrt/build_dir/hostpkg/ucode-2025.02.10~a8a11aea/platform.c'
FAILED: CMakeFiles/libucode.dir/platform.c.o 
/home/stijn/Development/OpenWrt/openwrt/staging_dir/host/bin/gcc -DHAVE_ARRAY_EXT -DHAVE_JSON_UINT64 -DHAVE_PARSE_END -DLIB_SEARCH_PATH="\"/home/stijn/Development/OpenWrt/openwrt/staging_dir/hostpkg/lib/ucode/*.so\", \"/home/stijn/Development/OpenWrt/openwrt/staging_dir/hostpkg/share/ucode/*.uc\", \"./*.so\", \"./*.uc\"" -DNDEBUG -D_FORTIFY_SOURCE=2 -D_GNU_SOURCE -Dlibucode_EXPORTS -I"/home/stijn/Development/OpenWrt/openwrt/build_dir/hostpkg/ucode-2025.02.10~a8a11aea/include" -I/home/stijn/Development/OpenWrt/openwrt/staging_dir/host/include/json-c -O2 -I/home/stijn/Development/OpenWrt/openwrt/staging_dir/host/include -I/home/stijn/Development/OpenWrt/openwrt/staging_dir/hostpkg/include -I/home/stijn/Development/OpenWrt/openwrt/staging_dir/target-aarch64_cortex-a53_musl/host/include -DNDEBUG -fPIC   -Os -Wall -Werror --std=gnu99 -ffunction-sections -fwrapv -Wextra -Werror=implicit-function-declaration -Wformat -Werror=format-security -Werror=format-nonliteral -Wmissing-declarations -Wno-error=unused-variable -Wno-unused-parameter -MD -MT CMakeFiles/libucode.dir/platform.c.o -MF CMakeFiles/libucode.dir/platform.c.o.d -o CMakeFiles/libucode.dir/platform.c.o -c '/home/stijn/Development/OpenWrt/openwrt/build_dir/hostpkg/ucode-2025.02.10~a8a11aea/platform.c'
<command-line>: error: "_FORTIFY_SOURCE" redefined [-Werror]
<built-in>: note: this is the location of the previous definition
cc1: all warnings being treated as errors

I suspect this is due to host gcc enabling _FORTIFY_SOURCE=3 by default, so the check added in cfb24ea doesn't work.

ossf/wg-best-practices-os-developers#659 contains some useful info and links about the problem.

Full build log: logspackageutilsucodehost-compile.txt

[jow-]

Please try this patch:

diff --git a/CMakeLists.txt b/CMakeLists.txt
index 858557e..c3bc2cb 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -1,6 +1,7 @@
 cmake_minimum_required(VERSION 3.13)
 include(CheckFunctionExists)
 include(CheckSymbolExists)
+include(CheckCSourceCompiles)
 
 project(ucode C)
 add_definitions(-Os -Wall -Werror --std=gnu99 -ffunction-sections -fwrapv -D_GNU_SOURCE)
@@ -10,7 +11,16 @@ if(CMAKE_C_COMPILER_VERSION VERSION_GREATER 6)
        add_definitions(-Wformat -Werror=format-security -Werror=format-nonliteral)
 endif()
 
-if(NOT CMAKE_C_FLAGS MATCHES -D_FORTIFY_SOURCE=)
+check_c_source_compiles("
+int main() {
+#ifndef _FORTIFY_SOURCE
+#error No fortification
+#endif
+       return 0;
+}
+" HAVE_FORTIFY_SOURCE)
+
+if(NOT HAVE_FORTIFY_SOURCE)
        add_definitions(-D_FORTIFY_SOURCE=2)
 endif()
 

[stintel]

That seems to work, thanks!

-- Performing Test HAVE_FORTIFY_SOURCE
-- Performing Test HAVE_FORTIFY_SOURCE - Success