zmq_poll returns prematurely even if infinite timeout is set - fixed

src/zmq.cpp

@@ -375,6 +375,7 @@ int zmq_poll (zmq_pollitem_t *items_, int nitems_, long timeout_)
         errno = EFAULT;
         return -1;
     }
+
     pollfd *pollfds = (pollfd*) malloc (nitems_ * sizeof (pollfd));
     zmq_assert (pollfds);
 
@@ -405,6 +406,8 @@ int zmq_poll (zmq_pollitem_t *items_, int nitems_, long timeout_)
     int timeout = timeout_ > 0 ? timeout_ / 1000 : -1;
     int nevents = 0;
 
+    while (true) {
+
         //  Wait for events. Ignore interrupts if there's infinite timeout.
         while (true) {
             int rc = poll (pollfds, nitems_, timeout);
@@ -436,9 +439,11 @@ int zmq_poll (zmq_pollitem_t *items_, int nitems_, long timeout_)
                     free (pollfds);
                     return -1;
                 }
-            if ((items_ [i].events & ZMQ_POLLOUT) && (zmq_events & ZMQ_POLLOUT))
+                if ((items_ [i].events & ZMQ_POLLOUT) &&
+                      (zmq_events & ZMQ_POLLOUT))
                     items_ [i].revents |= ZMQ_POLLOUT;
-            if ((items_ [i].events & ZMQ_POLLIN) && (zmq_events & ZMQ_POLLIN))
+                if ((items_ [i].events & ZMQ_POLLIN) &&
+                      (zmq_events & ZMQ_POLLIN))
                     items_ [i].revents |= ZMQ_POLLIN;
             }
             //  Else, the poll item is a raw file descriptor, simply convert
@@ -456,6 +461,14 @@ int zmq_poll (zmq_pollitem_t *items_, int nitems_, long timeout_)
                 nevents++;
         }
 
+        //  If timeout is set to infinite and we have to events to return
+        //  we can restart the polling.
+        if (timeout == -1 && nevents == 0)
+            continue;
+
+        break;
+    }
+
     free (pollfds);
     return nevents;
 
@@ -505,6 +518,8 @@ int zmq_poll (zmq_pollitem_t *items_, int nitems_, long timeout_)
     int nevents = 0;
     fd_set inset, outset, errset;
 
+    while (true) {
+
         //  Wait for events. Ignore interrupts if there's infinite timeout.
         while (true) {
             memcpy (&inset, &pollset_in, sizeof (fd_set));
@@ -569,9 +584,18 @@ int zmq_poll (zmq_pollitem_t *items_, int nitems_, long timeout_)
                 nevents++;
         }
 
+        //  If timeout is set to infinite and we have to events to return
+        //  we can restart the polling.
+        if (timeout_ < 0 && nevents == 0)
+            continue;
+
+        break;
+    }
+
     return nevents;
 
 #else
+    //  Exotic platforms that support neither poll() nor select().
     errno = ENOTSUP;
     return -1;
 #endif