zmq_unbind fail

bad-zmq-undbind.c

#include <zmq.h>
#include <assert.h>
#include <stdio.h>

int main(void)
{
    int rc;

    void *context = zmq_ctx_new();
    void *socket  = zmq_socket(context, ZMQ_SUB);
    assert(socket);
    
    int major, minor, patch;
    zmq_version(&major, &minor, &patch);

    printf("ZMQ VERSION=%d.%d.%d\n", major, minor, patch);

    rc = zmq_bind(socket, "tcp://*:5555");
    assert(rc == 0);

    char   endpoint[256];
    size_t endpoint_len = sizeof(endpoint);

    rc = zmq_getsockopt(socket, ZMQ_LAST_ENDPOINT, endpoint, &endpoint_len);
    assert(rc == 0);

    printf("LAST ENDPOINT=%s\n", endpoint);

    rc = zmq_unbind(socket, endpoint);
    if ( rc == -1 ) {
        perror("zmq_unbind");
        return 1;
    }

    return 0;
}