NAME

       io_fd - prepare descriptor for io_wait

SYNTAX

       #include <libowfat/io.h>

       int io_fd(int64 fd);

DESCRIPTION

       If you want to use io_canread() and io_canwrite() on a descriptor, you have to use io_wait() on it first,
       and io_wait() has to know which descriptors you are interested in. io_fd() informs io_wait() that you are
       interested in this fd.

       If  you  know  that the descriptor is writable, call io_fd_canwrite() instead. Most fresh descriptors are
       writable, e.g. if it came from pipe(2) or socketpair(2) or accept(2). This will save one syscall.

       io_pipe and io_socketpair already call io_fd_canwrite() for you.

       Waiting on descriptors only works for sockets, fifos and pipes.  It may also work on  devices  and  TTYs,
       but that is platform dependent -- you should not rely on that.  It does not work on files.

RETURN VALUE

       io_fd returns 1 on success, 0 on error.

SEE ALSO

       io_fd_canwrite(3), io_wait(3), io_wantread(3), io_canread(3), io_eagain(3), io_nonblock(3)

                                                                                                        io_fd(3)