Do not link shared library parts with "-pie -fPIE" as it breaks LTO

[darix]

Changing the linker commandline from

/usr/bin/cc -fPIC -O2 -Wall -D_FORTIFY_SOURCE=2 -fstack-protector-strong -funwind-tables -fasynchronous-unwind-tables -fstack-clash-protection -Werror=return-type -flto=auto -g -DNDEBUG -Wformat -Wformat-security -fstack-protector-strong -fPIC -fPIE -O2 -g -DNDEBUG -flto=auto -Wl,--as-needed -Wl,--no-undefined -Wl,-z,now -Wl,--no-undefined -pie -Wl,-z,relro -Wl,-z,now -shared -Wl,-soname,libpgagroal.so.1 -o libpgagroal.so.1.3.1 CMakeFiles/pgagroal.dir/libpgagroal/configuration.c.o CMakeFiles/pgagroal.dir/libpgagroal/logging.c.o CMakeFiles/pgagroal.dir/libpgagroal/management.c.o CMakeFiles/pgagroal.dir/libpgagroal/memory.c.o CMakeFiles/pgagroal.dir/libpgagroal/message.c.o CMakeFiles/pgagroal.dir/libpgagroal/network.c.o CMakeFiles/pgagroal.dir/libpgagroal/pipeline_perf.c.o CMakeFiles/pgagroal.dir/libpgagroal/pipeline_session.c.o CMakeFiles/pgagroal.dir/libpgagroal/pipeline_transaction.c.o CMakeFiles/pgagroal.dir/libpgagroal/pool.c.o CMakeFiles/pgagroal.dir/libpgagroal/prometheus.c.o CMakeFiles/pgagroal.dir/libpgagroal/remote.c.o CMakeFiles/pgagroal.dir/libpgagroal/security.c.o CMakeFiles/pgagroal.dir/libpgagroal/server.c.o CMakeFiles/pgagroal.dir/libpgagroal/shmem.c.o CMakeFiles/pgagroal.dir/libpgagroal/tracker.c.o CMakeFiles/pgagroal.dir/libpgagroal/utils.c.o CMakeFiles/pgagroal.dir/libpgagroal/worker.c.o  /usr/lib64/libev.so /usr/lib64/libssl.so /usr/lib64/libcrypto.so /usr/lib64/libsystemd.so 
/usr/lib64/gcc/x86_64-suse-linux/11/../../../../x86_64-suse-linux/bin/ld: /tmp/ccoNOkYP.ltrans0.ltrans.o: warning: relocation against `stdout@@GLIBC_2.2.5' in read-only section `.text'
/usr/lib64/gcc/x86_64-suse-linux/11/../../../../x86_64-suse-linux/bin/ld: /tmp/ccoNOkYP.ltrans0.ltrans.o: relocation R_X86_64_PC32 against symbol `shmem' can not be used when making a shared object; recompile with -fPIC
/usr/lib64/gcc/x86_64-suse-linux/11/../../../../x86_64-suse-linux/bin/ld: final link failed: bad value
collect2: error: ld returned 1 exit status

to

/usr/bin/cc -fPIC -O2 -Wall -D_FORTIFY_SOURCE=2 -fstack-protector-strong -funwind-tables -fasynchronous-unwind-tables -fstack-clash-protection -Werror=return-type -flto=auto -g -DNDEBUG -Wformat -Wformat-security -fstack-protector-strong -fPIC -O2 -g -DNDEBUG -flto=auto -Wl,--as-needed -Wl,--no-undefined -Wl,-z,now -Wl,--no-undefined -Wl,-z,relro -Wl,-z,now -shared -Wl,-soname,libpgagroal.so.1 -o libpgagroal.so.1.3.1 CMakeFiles/pgagroal.dir/libpgagroal/configuration.c.o CMakeFiles/pgagroal.dir/libpgagroal/logging.c.o CMakeFiles/pgagroal.dir/libpgagroal/management.c.o CMakeFiles/pgagroal.dir/libpgagroal/memory.c.o CMakeFiles/pgagroal.dir/libpgagroal/message.c.o CMakeFiles/pgagroal.dir/libpgagroal/network.c.o CMakeFiles/pgagroal.dir/libpgagroal/pipeline_perf.c.o CMakeFiles/pgagroal.dir/libpgagroal/pipeline_session.c.o CMakeFiles/pgagroal.dir/libpgagroal/pipeline_transaction.c.o CMakeFiles/pgagroal.dir/libpgagroal/pool.c.o CMakeFiles/pgagroal.dir/libpgagroal/prometheus.c.o CMakeFiles/pgagroal.dir/libpgagroal/remote.c.o CMakeFiles/pgagroal.dir/libpgagroal/security.c.o CMakeFiles/pgagroal.dir/libpgagroal/server.c.o CMakeFiles/pgagroal.dir/libpgagroal/shmem.c.o CMakeFiles/pgagroal.dir/libpgagroal/tracker.c.o CMakeFiles/pgagroal.dir/libpgagroal/utils.c.o CMakeFiles/pgagroal.dir/libpgagroal/worker.c.o  /usr/lib64/libev.so /usr/lib64/libssl.so /usr/lib64/libcrypto.so /usr/lib64/libsystemd.so 

fixes the build with LTO

[jesperpedersen]

Thanks @darix !

Will be in 1.3.2 -- pushed similar fix for pgmoneta and pgexporter

[darix]

The fix in git was not enough

Index: pgagroal-1.3.2/src/CMakeLists.txt
===================================================================
--- pgagroal-1.3.2.orig/src/CMakeLists.txt
+++ pgagroal-1.3.2/src/CMakeLists.txt
@@ -143,7 +143,6 @@ if (CMAKE_BUILD_TYPE MATCHES Release OR
   if (${CMAKE_SYSTEM_NAME} STREQUAL "Linux")
     check_c_compiler_flag(-fPIE HAS_PIE)
     if (HAS_PIE)
-      set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -fPIE")
       set (CMAKE_EXE_LINKER_FLAGS "${CMAKE_EXE_LINKER_FLAGS} -pie")
     endif()
   endif()

[darix]

the whole PIE check can probably replaced with

https://cmake.org/cmake/help/latest/module/CheckPIESupported.html

[jesperpedersen]

What is your compiler tool chain ?

You have to compile with -fPIE for the linking with -pie to work.

Will have to look into the CheckPIESupported check - thanks for the link !

[darix]

you can also build all object files with -fPIC ​and then just link with -fPIE -pie

the problem arises from trying to link with LTO. I thought fedora would have turned on LTO by default as well and you would see the same issue there.

with the code you had so far ... it passes -fPIE also when linking the shared library. and that is wrong. but i think relying on the cmake helper is probably a better idea anyway.