C code to illustrate issue LIBZMQ-256 problem with IDENTITY

256/3-0/README

@@ -0,0 +1,5 @@
+To avoid loading a system-wide 0mq library, place
+the C libraries here. This let's you run your Ruby
+code with a 0mq C library build that is different
+from the system-wide one. This can be handy for
+rolling upgrades or testing.

256/3-0/issue.c

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+//
+//  Custom IDENTITY values are not preserved as
+//  they are passed from one socket to another.
+//
+// gcc -lzmq issue.c
+// chmod +x a.out
+// ./a.out
+//
+#include <zmq.h>
+
+
+// several of these are probably unnecessary...
+#include <stdint.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <string.h>
+#include <sys/time.h>
+#include <time.h>
+#include <unistd.h>
+#include <assert.h>
+#include <inttypes.h>
+
+
+
+int main (void) 
+{
+      int rc;
+      void *context = zmq_init (1);
+      void *sender = zmq_socket (context, ZMQ_REQ);
+      void *receiver = zmq_socket (context, ZMQ_XREP);
+
+      // set a custom IDENTITY
+      assert (0 == zmq_setsockopt (sender, ZMQ_IDENTITY, "Custom", 6));
+      assert (0 == zmq_bind (receiver, "tcp://127.0.0.1:7557"));
+      assert (0 == zmq_connect (sender, "tcp://127.0.0.1:7557"));
+
+      zmq_msg_t m1, m2;
+      assert (0 == zmq_msg_init_data (&m1, "Hello world", 11, NULL, NULL));
+      assert (11 == zmq_sendmsg(sender, &m1, 0));
+
+      assert (0 == zmq_msg_init (&m2) );
+      assert (-1 != zmq_recvmsg (receiver, &m2, 0));
+
+      int label, more;
+      size_t size = sizeof (label);
+
+      do {
+         assert (0 == zmq_msg_init (&m2));
+         assert (-1 != zmq_recvmsg (receiver, &m2, 0));
+         assert (0 == zmq_getsockopt (receiver, ZMQ_RCVLABEL, &label, &size));
+         assert (0 == zmq_getsockopt (receiver, ZMQ_RCVMORE, &more, &size));
+
+         if (label)
+            printf ("LABEL (should be 'Custom'): %s\n", (char*) zmq_msg_data (&m2));
+         else
+            printf ("Contents: %s\n", (char*) zmq_msg_data (&m2));
+      }
+      while ( (label == 1) || (more == 1));
+
+      zmq_close (sender);
+      zmq_close (receiver);
+      zmq_term (context);
+      return (0);
+}