NAME

       iob_write - send I/O batch through callback

SYNTAX

       #include <iob.h>

       typedef int64 (*io_write_callback)(int64 s,const void* buf,uint64 n);

       int64 iob_write(int64 s,io_batch* b,io_write_callback cb);

DESCRIPTION

       iob_write  sends the (rest of) b through the callback cb, passing s as first argument.  cb
       is expected to behave like io_trywrite(2).

       This interface is intended to send an I/O batch through a filter, for example  to  encrypt
       or compress it.  If you just want to send an I/O batch to a socket, use iob_send instead.

       iob_write returns the number of bytes written, 0 if there were no more bytes to be written
       in the batch, -1 for EAGAIN, or -3 for a permanent error (for example "connection reset by
       peer").

       The  normal usage pattern is using io_wait to know when a descriptor is writable, and then
       calling iob_write until it returns 0, -1 or -3.

       If iob_write returns 0, terminate the loop (everything was written OK).  If it returns -1,
       call io_wait again.  If it returned -3, signal an error.

       The callback is supposed to behave like write(2), i.e. return the number of bytes written,
       0 for EOF, -1 for error (iob_write will return -3 then).  Return -1 with errno==EAGAIN  if
       using non-blocking I/O when we need to wait for the next write event.  iob_write will then
       return -1.

NOTE

       iob_write will continue to call your callback until it returns an error.  So if you are in
       a  state  machine, for example a web server using this for SSL support, make sure to write
       at most n bytes at a time (e.g.  64k)  and  the  next  time  you  are  called  return  -1.
       Otherwise iob_write might not return until the whole file is served.

SEE ALSO

       iob_send(3)

                                                                                     iob_write(3)