bionic (3) io_canwrite.3.gz

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)