Problem: zmq_ctx_term asserts with connect-before-bind and sockets with identity over inproc transport

Solution: check if the connecting inproc socket has been closed
before trying to send the identity.
Otherwise the pipe will be in waiting_for_delimiter state causing
writes to fail and the connect to assert when the context is being
torn down and the pending inproc connects are resolved.
Add test case that covers this behaviour.

src/ctx.cpp

@@ -573,7 +573,13 @@ void zmq::ctx_t::connect_inproc_sockets (zmq::socket_base_t *bind_socket_,
     else
         pending_connection_.connect_pipe->send_bind (bind_socket_, pending_connection_.bind_pipe, false);
 
-    if (pending_connection_.endpoint.options.recv_identity) {
+    // When a ctx is terminated all pending inproc connection will be
+    // connected, but the socket will already be closed and the pipe will be
+    // in waiting_for_delimiter state, which means no more writes can be done
+    // and the identity write fails and causes an assert. Check if the socket
+    // is open before sending.
+    if (pending_connection_.endpoint.options.recv_identity &&
+            pending_connection_.endpoint.socket->check_tag ()) {
         msg_t id;
         const int rc = id.init_size (bind_options.identity_size);
         errno_assert (rc == 0);

tests/test_inproc_connect.cpp

@@ -212,6 +212,30 @@ void test_connect_before_bind_pub_sub ()
     assert (rc == 0);
 }
 
+void test_connect_before_bind_ctx_term ()
+{
+    void *ctx = zmq_ctx_new ();
+    assert (ctx);
+
+    for (int i = 0; i < 20; ++i) {
+        // Connect first
+        void *connectSocket = zmq_socket (ctx, ZMQ_ROUTER);
+        assert (connectSocket);
+
+        char ep[20];
+        sprintf(ep, "inproc://cbbrr%d", i);
+        int rc = zmq_connect (connectSocket, ep);
+        assert (rc == 0);
+
+        // Cleanup
+        rc = zmq_close (connectSocket);
+        assert (rc == 0);
+    }
+
+    int rc = zmq_ctx_term (ctx);
+    assert (rc == 0);
+}
+
 void test_multiple_connects ()
 {
     const unsigned int no_of_connects = 10;
@@ -499,6 +523,7 @@ int main (void)
     test_bind_before_connect ();
     test_connect_before_bind ();
     test_connect_before_bind_pub_sub ();
+    test_connect_before_bind_ctx_term ();
     test_multiple_connects ();
     test_multiple_threads ();
     test_simultaneous_connect_bind_threads ();