combining static libraries

Question

Suppose I have a number of C static libraries say libColor.a which depends on libRGB.a which in turn depends on libPixel.a . The library libColor.a is said to depend on library libRGB.a since there are some references in libColor.a to some of symbols defined in libRGB.a. How do I combine all the above libraries to a new libNewColor.a which is independent?

Independent means the new library should have all symbols defined. So while linking I just need to give -lNewColor. The size of the new library should be minimal i.e it should not contain any symbols in libRGB.a which is not used by libColor.a etc. I tried my luck using various options in ar command (used to create and update static libraries/archives).

Answer 1

A static library is not much more than an archive of some object files (.o). What you can do is extract all the objects in the two libraries (using "ar x") and then use "ar" to link them together in a new library.

Answer 2

1/ Extract ALL of the object files from each library (using ar) and try to compile your code without the libraries or any of the object files. You'll get an absolute bucket-load of undefined symbols. If you get no undefined symbols, go to step 5.

2/ Grab the first one and find out which object file satisfies that symbol (using nm).

3/ Write down that object file then compile your code, including the new object file. You'll get a new list of undefined symbols or, if there's none, go to step 5.

4/ Go to step 2.

5/ Combine all the object files in your list into a single library (again with ar).

Bang! There you have it. Try to link your code without any of the objects but with the new library.

This whole thing could be relatively easily automated with a shell script.