sendfile() usage on two mmaped files (linux)

Can sendfile() linux syscall be used to send part of file from one mmaped file to other mmaped fi开发者_运维百科le?

From sendfile(2):

Presently (Linux 2.6.9): in_fd, must correspond to a file which supports mmap()-like operations (i.e., it cannot be a socket); and out_fd must refer to a socket.

So it looks like the answer is no.

Edit

I think I understand what you are looking for now. Check out splice(2).