Extract static object from dynamic one

[Thomas Köppe]

Hello,

I've been wondering about a relatively simple question for which there 
seems to be no obvious answer - am I overlooking something?

Suppose I have a dynamic C library libfoo.so (or foo.dll) along with 
headers in foo.h. Is it possible to build from the binary a static 
library libfoo.a?

I'm thinking that this should be easy, since I know all the function 
signatures and entry points in the binary; is there some way (maybe with 
objcopy or objdump?) in which I can extract the binary code for a 
specific function?

Thank you very much,

Thomas K.