zmq_msg_init_data - initialise 0MQ message from a supplied buffer

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0MQ 4.3.5                                          03/31/2024                               ZMQ_MSG_INIT_DATA(3)

       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.

ENOMEM
           Insufficient storage space is available.

Initialisingamessagefromasuppliedbuffer.

           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);

       zmq_msg_init_data - initialise 0MQ message from a supplied buffer

       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.

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)

typedefvoid(zmq_free_fn)(void*data,void*hint);intzmq_msg_init_data(zmq_msg_t*msg,void*data,size_tsize,zmq_free_fn*ffn,void*hint);