Update zmq_msg_get(ZMQ_SHARED) to return true for type_cmsg messages

doc/zmq_msg_get.txt

@@ -24,14 +24,14 @@ The following properties can be retrieved with the _zmq_msg_get()_ function:
 Indicates that there are more message frames to follow after the 'message'.
 
 *ZMQ_SRCFD*::
-Returns the file descriptor of the socket the 'message' was read from. This 
-allows application to retrieve the remote endpoint via 'getpeername(2)'. Be 
-aware that the respective socket might be closed already, reused even. 
+Returns the file descriptor of the socket the 'message' was read from. This
+allows application to retrieve the remote endpoint via 'getpeername(2)'. Be
+aware that the respective socket might be closed already, reused even.
 Currently only implemented for TCP sockets.
 
 *ZMQ_SHARED*::
-Indicates that a message has been copied and MAY share underlying storage
-with another copy of this message.
+Indicates that a message MAY share underlying storage with another copy of
+this message.
 
 RETURN VALUE
 ------------

src/zmq.cpp

@@ -214,7 +214,7 @@ void *zmq_init (int io_threads_)
         return ctx;
     }
     errno = EINVAL;
-    return NULL;   
+    return NULL;
 }
 
 int zmq_term (void *ctx_)
@@ -366,7 +366,7 @@ int zmq_send (void *s_, const void *buf_, size_t len_, int flags_)
         errno = err;
         return -1;
     }
-    
+
     //  Note the optimisation here. We don't close the msg object as it is
     //  empty anyway. This may change when implementation of zmq_msg_t changes.
     return rc;
@@ -392,7 +392,7 @@ int zmq_send_const (void *s_, const void *buf_, size_t len_, int flags_)
         errno = err;
         return -1;
     }
-    
+
     //  Note the optimisation here. We don't close the msg object as it is
     //  empty anyway. This may change when implementation of zmq_msg_t changes.
     return rc;
@@ -415,7 +415,7 @@ int zmq_sendiov (void *s_, iovec *a_, size_t count_, int flags_)
     int rc = 0;
     zmq_msg_t msg;
     zmq::socket_base_t *s = (zmq::socket_base_t *) s_;
-    
+
     for (size_t i = 0; i < count_; ++i) {
         rc = zmq_msg_init_size (&msg, a_[i].iov_len);
         if (rc != 0) {
@@ -435,7 +435,7 @@ int zmq_sendiov (void *s_, iovec *a_, size_t count_, int flags_)
            break;
         }
     }
-    return rc; 
+    return rc;
 }
 
 // Receiving functions.
@@ -488,7 +488,7 @@ int zmq_recv (void *s_, void *buf_, size_t len_, int flags_)
 }
 
 // Receive a multi-part message
-// 
+//
 // Receives up to *count_ parts of a multi-part message.
 // Sets *count_ to the actual number of parts read.
 // ZMQ_RCVMORE is set to indicate if a complete multi-part message was read.
@@ -499,7 +499,7 @@ int zmq_recv (void *s_, void *buf_, size_t len_, int flags_)
 // *count_ to retrieve message parts successfully read,
 // even if -1 is returned.
 //
-// The iov_base* buffers of each iovec *a_ filled in by this 
+// The iov_base* buffers of each iovec *a_ filled in by this
 // function may be freed using free().
 // TODO: this function has no man page
 //
@@ -514,11 +514,11 @@ int zmq_recviov (void *s_, iovec *a_, size_t *count_, int flags_)
     size_t count = *count_;
     int nread = 0;
     bool recvmore = true;
-    
+
     *count_ = 0;
 
     for (size_t i = 0; recvmore && i < count; ++i) {
-       
+
         zmq_msg_t msg;
         int rc = zmq_msg_init (&msg);
         errno_assert (rc == 0);
@@ -630,7 +630,8 @@ int zmq_msg_get (zmq_msg_t *msg_, int property_)
             // warning: int64_t to int
             return ((zmq::msg_t*) msg_)->fd ();
         case ZMQ_SHARED:
-            return (((zmq::msg_t*) msg_)->flags () & zmq::msg_t::shared)? 1: 0;
+            return (((zmq::msg_t*) msg_)->is_cmsg ()) ||
+                   (((zmq::msg_t*) msg_)->flags () & zmq::msg_t::shared)? 1: 0;
         default:
             errno = EINVAL;
             return -1;

tests/test_msg_flags.cpp

@@ -25,19 +25,19 @@ int main (void)
     //  Create the infrastructure
     void *ctx = zmq_ctx_new ();
     assert (ctx);
-    
+
     void *sb = zmq_socket (ctx, ZMQ_ROUTER);
     assert (sb);
-    
+
     int rc = zmq_bind (sb, "inproc://a");
     assert (rc == 0);
-    
+
     void *sc = zmq_socket (ctx, ZMQ_DEALER);
     assert (sc);
-    
+
     rc = zmq_connect (sc, "inproc://a");
     assert (rc == 0);
-   
+
     //  Send 2-part message.
     rc = zmq_send (sc, "A", 1, ZMQ_SNDMORE);
     assert (rc == 1);
@@ -65,7 +65,7 @@ int main (void)
     more = zmq_msg_more (&msg);
     assert (more == 0);
 
-    // Test ZMQ_SHARED property
+    // Test ZMQ_SHARED property (case 1, refcounted messages)
     zmq_msg_t msg_a;
     rc = zmq_msg_init_size(&msg_a, 1024); // large enough to be a type_lmsg
     assert (rc == 0);
@@ -85,13 +85,31 @@ int main (void)
     rc = zmq_msg_get(&msg_b, ZMQ_SHARED);
     assert (rc == 1);
 
+    // cleanup
+    rc = zmq_msg_close(&msg_a);
+    assert (rc == 0);
+    rc = zmq_msg_close(&msg_b);
+    assert (rc == 0);
+
+    // Test ZMQ_SHARED property (case 2, constant data messages)
+    rc = zmq_msg_init_data(&msg_a, (void*) "TEST", 5, 0, 0);
+    assert (rc == 0);
+
+    // Message reports as shared
+    rc = zmq_msg_get(&msg_a, ZMQ_SHARED);
+    assert (rc == 1);
+
+    // cleanup
+    rc = zmq_msg_close(&msg_a);
+    assert (rc == 0);
+
     //  Deallocate the infrastructure.
     rc = zmq_close (sc);
     assert (rc == 0);
-    
+
     rc = zmq_close (sb);
     assert (rc == 0);
-    
+
     rc = zmq_ctx_term (ctx);
     assert (rc == 0);
     return 0 ;