ZMQ_MSG_INIT_DATA(3)              0MQ Manual              ZMQ_MSG_INIT_DATA(3)

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.

0MQ 4.3.5                         10/23/2023              ZMQ_MSG_INIT_DATA(3)