NAME

       io_fd_canwrite - prepare descriptor for io_wait

SYNTAX

       #include <io.h>

       int io_fd(int64 fd); int io_fd_canwrite(int64 fd);

DESCRIPTION

       io_fd_canwrite  is  just like io_fd, except that assumes the descriptor is writable, which
       may save a syscall or two.  This assumption is true in  most  cases,  because  the  kernel
       buffers writes.  Noteworthy cases in which you need to use io_fd instead of io_fd_canwrite
       are unconnected sockets, i.e. when you queued a non-blocking connect() and want to ask for
       writability to get notified when it went through.

       It is OK to call this function on a descriptor that io_fd() has already been called on.

RETURN VALUE

       io_fd_canwrite returns 1 on success, 0 on error.

SEE ALSO

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

                                                                                io_fd_canwrite(3)