Static compilation in linux using g++

Question

I compiled OpenSSL libraries statically. I want to compile MyModule with OpenSSL libraries statically. I am using a Makefile to do the same with

LDFLAGS      = $(LD_SHARED_FLAGS) -fPIC -static -lssl -lcrypto

LD_SHARED_FLAGS in root Makefile has

LD_SHARED_FLAGS     = -z text

When I run make, I get this,

g++ -shared -L../../lib  -z text -fPIC -static -lssl -lcrypto  -o libMyModule.so debug_utils.o  MyModule.o   labels.o -L/path_to_openssl/lib -lssl -lcrypto -lc

/usr/bin/ld: /usr/lib/gcc/x86_64-redhat-linux/4.8.5/crtbeginT.o: relocation R_X86_64_32 against `__TMC_END__' can not be used when making a shared object; recompile with -fPIC

/usr/lib/gcc/x86_64-redhat-linux/4.8.5/crtbeginT.o: error adding symbols: Bad value

collect2: error: ld returned 1 exit status

make: *** [libMyModule.so] Error 1

Am I using the right flags for static compilation?

How do I fix this error?

Answer 1

It appears you want to link your static libraries libssl.a and libcrypto.a into your shared library libMyModule.so.

Adding the GCC option -static to your linkage command does not have just that effect, but a much bigger one. It's effect is to request a fully static linkage. The linker must find and use static versions of all required libraries: not just the ones you specify in your linkage command but also the default ones: libc, libstdc++, libgcc, and also the static-linkage variants of the C runtime support binaries, crt*.o.

Probably, you don't want all that -static stuff, and even if you don't mind having it, it is incompatible with -shared.

You need -shared, of course, to make a shared library. All object files that are linked into a shared library must be Position Independent Code, compiled with -fPIC.

The error you encounter:

/usr/bin/ld: /usr/lib/gcc/x86_64-redhat-linux/4.8.5/crtbeginT.o: \
relocation R_X86_64_32 against `__TMC_END__' can not be used when making a shared object; \
recompile with -fPIC

tells you that the C runtime binary crtbeginT.o required for your linkage wasn't compiled with -fPIC; isn't position-indpendent code and therefore can't be linked into a shared library.

But crtbeginT.o is required for your linkage by the -static option. If you didn't specify -static, then crtbeginS.o would be linked instead, which is the PIC variant of this runtime binary, for linking with shared libraries, and the error would not occur.

So don't specify -static. It doesn't mix with -shared and it is not the way to link static versions of libssl and libcrypto into libMyModule.so.

There is more than one way to achieve that. The simplest is to replace -lssl -lcrypto in your linkage command with options that explictly specify the static versions of just those libraries, i.e.

-l:libssl.a -l:libcrypto.a