>> See unix(4) and its description of passing fd's via a "cmsghdr".
>
>Uh, hello, that's *exactly* what I've been proposing all along: exec
>a small program that only your program can run (because it's group-execute
>only, and your program's setgid that group) that is setuid root; the small,
>easily verified program gets the descriptor you want and passes it back to
>you.

actually...it might be *simpler* to simply fork() and then call a
specific function that *only* exits (ie, never returns).  sort of like
threads.

that function can handle requests from the parent for things like file
descriptors or the contents of files.  the pipe set up is a little
easier, as well as the fact that you don't have to worry that the
"helper" program is there.

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