NAME

       io_canwrite - return a file descriptor that can be written to

SYNTAX

       #include <io.h>

       int64 io_canwrite();

DESCRIPTION

       io_canwrite  returns  the  next  file descriptor that can be written to.  You have to have
       used io_wantwrite() on the file descriptor earlier, and you have to have called  io_wait()
       or io_waituntil().

       These  functions  then  keep an internal data structure on which descriptors were reported
       writable by the operating system.

       Please note that there is no guarantee that you can still write data without  blocking  to
       that  descriptor,  just  that  you  could  when  io_wait()  or io_waituntil() were called.
       Another process could have  written  something  before  you.   Look  at  the  result  from
       io_trywrite().

       If  there are no more descriptors that you can write to without blocking, io_canwrite will
       return -1.  In this case you should call io_wait() or io_waituntil() again.

       You should only use io_trywrite(3), io_sendfile(3) or iob_send(3) to write  to  the  file,
       not plain write(2).  If you use write(2) and get EAGAIN, call io_eagain(3).

SEE ALSO

       io_wait(3), io_canwrite(3)

                                                                                   io_canwrite(3)