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2417

answers:

3

I have a third-party library which consists mainly of a large number of static (.a) library files. I can compile this into a single .a library file, but I really need it to be a single .so shared library file.

Is there any way to convert a static .a file into a shared .so file? Or more generally is there a good way to combine a huge number of static .a files with a few .o object files into a single .so file?

+3  A: 

Does this (with appropriate -L's of course)

gcc -shared -o megalib.so foo.o bar.o -la_static_lib -lb_static_lib

Not do it?

dicroce
Using gcc -shared did the trick, but only after I recompiled with -fPIC. Thanks for pointing me in the right direction!
Eli Courtwright
+6  A: 

You can't do this if objects within static library was compiled without -fPIC or like.

vitaly.v.ch
On well-supported targets, `PIC` is not essential for shared library code. It just results in much more efficient use of memory (the majority, instead of a minority, of pages can be shared) at the expense of some performance.
R..
+1  A: 

g++ -shared -o megalib.so foo.o bar.o -Wl,--whole-archive -la_static_lib -lb_static_lib -Wl,--no-whole-archive -lc_static_lib -lother_shared_object

I'm not sure about gcc, but for g++ I had to add the --whole-archive linker option to include the objects from the static libraries in the shared object. The --no-whole-archive option is necessary if you want to link to libc_static_lib.a and libother_shared_object.so, but not include them as a whole in megalib.so.

Calm