Can I build a shared library by linking static libraries?

Question

I have a bunch of static libraries (*.a), and I want to build a shared library (*.so) to link against those static libraries (*.a). How can I do so in gcc/g++?

Answer 1

You can (just extract all the .o files and link them with -shared to make a .so), but whether it works, and how well it works, depends on the platform and whether the static library was compiled as position-independent code (PIC). On some platforms (e.g. x86_64), non-PIC code is not valid in shared libraries and will not work (actually I think the linker will refuse to make the .so). On other platforms, non-PIC code will work in shared libraries, but the in-memory copy of the library is not sharable between different programs using it or even different instances of the same program, so it will result in HUGE memory bloat.

Answer 2

I can't see why you couldn't just build the files of your dynamic library to .o files and link with;

gcc -shared *.o -lstaticlib1 -lstaticlib2 -o mylib.so