NAME

       io_fd_flags - prepare descriptor for io_wait

SYNTAX

       #include <libowfat/io.h>

       int io_fd(int64 fd);

       #ifdef HAVE_IO_FD_FLAGS

       int io_fd_flags(int64 fd);

DESCRIPTION

       io_fd_flags  behaves just like io_fd, but certain flags can be bitwise-ORed to it to alter
       its behavior:

       IO_FD_CANWRITE
              tell io_fd that the descriptor is writable.  This is  useful  so  io_wantwrite  can
              queue the descriptor immediately and there is no need to query the operating system
              event reporting mechanism.

       IO_FD_BLOCK
              tell io_fd that the descriptor is blocking.

       IO_FD_NONBLOCK
              tell io_fd that the descriptor is non-blocking.

       Normally, io_fd calls fcntl to ask the operating system whether the descriptor is blocking
       or  not.   The  frameworks  needs to know because it alters how io_tryread and io_trywrite
       handle the socket.  Never pass both IO_FD_BLOCK and IO_FD_NONBLOCK at the same time.

       Newly connected stream sockets are always writable if the connection is established, so it
       is  usually  safe  to  pass  IO_FD_CANWRITE.  The main exception case where IO_FD_CANWRITE
       should not be passed is on a non-blocking socket where a connect() is pending.   Then  you
       need to poll for writability to get notified when the connection is established.

RETURN VALUE

       io_fd_flags returns 1 on success, 0 on error.

SEE ALSO

       io_fd(3), io_fd_canwrite(3)

                                                                                   io_fd_flags(3)