Self-contained shared library

Question

I need to create a shared library whose own dependencies including libc/libstdc++ have to be statically linked to it to produce a self-contained binary. I tried to do this

g++ -c -fpic -o foo.o foo.cpp
g++ -static -shared -o foo.so foo.o

which fails with:

/usr/bin/ld.bfd.real: /usr/local/lib/gcc/x86_64-unknown-linux-gnu/5.2.0/crtbeginT.o: relocation R_X86_64_32 against `__TMC_END__' can not be      used when making a shared object; recompile with -fPIC
/usr/local/lib/gcc/x86_64-unknown-linux-gnu/5.2.0/crtbeginT.o: could not read symbols: Bad value
collect2: error: ld returned 1 exit status

Can somebody tell me what I am doing wrong?

Answer 1

You can use the -static-libstdc++ option to link libstdc++ statically. You probably shouldn't link statically to libc (or libgcc, which you can link statically with -static-libgcc should you need to) if you're making a dynamic library; you'll want to pick up the libc version of the application that loads your shared library.

Other options controlling static linking can be found in the GCC manual. You may also be able to achieve the desired results by passing arguments to the linker (-Wl,<argument>, or calling ld directly). The LD manual lists the permitted options.

---

Example:

I wrote the following code

#include <iostream>

extern "C" void do_something() {
    std::cout << "Doing something!\n";
}

and compiled it to a .o file as follows:

g++ -fPIC -c -o tmp.o tmp.cpp

I then produced two shared libraries from it. One with -static-libstdc++, and one without:

g++ -shared -o tmp-shared.so tmp.o
g++ -shared -static-libstdc++ -o tmp-static.so tmp.o

For comparison, ldd tmp-shared.so:

linux-vdso.so.1 =>  (0x00007fffc6dfd000)
libstdc++.so.6 => /usr/lib64/libstdc++.so.6 (0x00002b708cb43000)
libm.so.6 => /lib64/libm.so.6 (0x00002b708ce4c000)
libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x00002b708d0cf000)
libc.so.6 => /lib64/libc.so.6 (0x00002b708d2dd000)
/lib64/ld-linux-x86-64.so.2 (0x00000035c6c00000)

and ldd tmp-static.so:

linux-vdso.so.1 =>  (0x00007fff99bfd000)
libm.so.6 => /lib64/libm.so.6 (0x00002acbec030000)
libgcc_s.so.1 => /lib64/libgcc_s.so.1 (0x00002acbec2b3000)
libc.so.6 => /lib64/libc.so.6 (0x00002acbec4c1000)
/lib64/ld-linux-x86-64.so.2 (0x00000035c6c00000)