Is it possible to redirect stdout as stdin to same program?

Question

I am writing a filter, and I am exploring an approach to write the program. I was wondering if this is possible: from input in stdin, write to stdout, but redirect this stdout such that the program reads the generated stdout as if it were stdin, again, thus re-processing the data. I do not wish to store the data in a gigantic array -- I wish to do this using streams, solely. Is this even possible? (if not, that's fine too.) Also, a note: I wish to do this only in a single source file of C code.

Answer 1

Create a pipe. Duplicate the read-end of the pipe as the new STDIN_FILENO, the write-end as STDOUT_FILENO, and you're all set. Everything you now write to stdout will be available on stdin.