NAME

       zmq_msg_init_data - initialise 0MQ message from a supplied buffer

SYNOPSIS

       typedef void (zmq_free_fn) (void *data, void *hint);

       int zmq_msg_init_data (zmq_msg_t *msg, void *data, size_t size, zmq_free_fn *ffn, void
       *hint);

DESCRIPTION

       The zmq_msg_init_data() function shall initialise the message object referenced by msg to
       represent the content referenced by the buffer located at address data, size bytes long.
       No copy of data shall be performed and 0MQ shall take ownership of the supplied buffer.

       If provided, the deallocation function ffn shall be called once the data buffer is no
       longer required by 0MQ, with the data and hint arguments supplied to zmq_msg_init_data().

           Caution
           Never access zmq_msg_t members directly, instead always use the zmq_msg family of
           functions.

           Caution
           The deallocation function ffn needs to be thread-safe, since it will be called from an
           arbitrary thread.

           Caution
           If the deallocation function is not provided, the allocated memory will not be freed,
           and this may cause a memory leak.

           Caution
           The functions zmq_msg_init(), zmq_msg_init_data(), zmq_msg_init_size() and
           zmq_msg_init_buffer() are mutually exclusive. Never initialise the same zmq_msg_t
           twice.

RETURN VALUE

       The zmq_msg_init_data() function shall return zero if successful. Otherwise it shall
       return -1 and set errno to one of the values defined below.

ERRORS

       ENOMEM
           Insufficient storage space is available.

EXAMPLE

       Initialising a message from a supplied buffer.

           void my_free (void *data, void *hint)
           {
               free (data);
           }

               /*  ...  */

           void *data = malloc (6);
           assert (data);
           memcpy (data, "ABCDEF", 6);
           zmq_msg_t msg;
           rc = zmq_msg_init_data (&msg, data, 6, my_free, NULL);
           assert (rc == 0);

SEE ALSO

       zmq_msg_init_size(3) zmq_msg_init_buffer(3) zmq_msg_init(3) zmq_msg_close(3)
       zmq_msg_data(3) zmq_msg_size(3) zmq(7)

AUTHORS

       This page was written by the 0MQ community. To make a change please read the 0MQ
       Contribution Policy at http://www.zeromq.org/docs:contributing.