Problem: inconsistent behaviour of zmq_poller_add and zmq_poller_add_fd in case…

Problem: inconsistent behaviour of zmq_poller_add and zmq_poller_add_fd in case of memory exhaustion

Solution: always return -1 with errno == ENOMEM

src/socket_poller.cpp

@@ -137,7 +137,13 @@ int zmq::socket_poller_t::add (socket_base_t *socket_,
         -1
 #endif
     };
-    items.push_back (item);
+    try {
+        items.push_back (item);
+    }
+    catch (const std::bad_alloc &) {
+        errno = ENOMEM;
+        return -1;
+    }
     need_rebuild = true;
 
     return 0;
@@ -162,7 +168,13 @@ int zmq::socket_poller_t::add_fd (fd_t fd_, void *user_data_, short events_)
         -1
 #endif
     };
-    items.push_back (item);
+    try {
+        items.push_back (item);
+    }
+    catch (const std::bad_alloc &) {
+        errno = ENOMEM;
+        return -1;
+    }
     need_rebuild = true;
 
     return 0;