Explicitly handle listen sockets and connection sockets differently in Linux and Mac OS eventhandler

runtime/bin/eventhandler_linux.cc

Index: runtime/bin/eventhandler_linux.cc
diff --git a/runtime/bin/eventhandler_linux.cc b/runtime/bin/eventhandler_linux.cc
index a72f42a36ed6794f39ba5208ff642246e2e72e5a..0f60633aea5805c940af41b66b053e11022ed579 100644
--- a/runtime/bin/eventhandler_linux.cc
+++ b/runtime/bin/eventhandler_linux.cc
@@ -96,6 +96,11 @@ Dart_Port EventHandlerImplementation::PortFor(intptr_t fd) {
 }
 
 
+bool EventHandlerImplementation::IsListeningSocket(intptr_t fd) {
+  return (port_map_[fd].mask & (1 << kListeningSocket)) != 0;
+}
+
+
 void EventHandlerImplementation::RegisterFdWakeup(intptr_t id,
                                                   Dart_Port dart_port,
                                                   intptr_t data) {
@@ -136,17 +141,15 @@ void EventHandlerImplementation::WakeupHandler(intptr_t id,
 
 void EventHandlerImplementation::SetPollEvents(struct pollfd* pollfds,
                                                intptr_t mask) {
-  /*
-   * We do not set POLLERR and POLLHUP explicitly since they are triggered
-   * anyway.
-   */
-  pollfds->events |= POLLRDHUP;
+  // Do not ask for POLLERR and POLLHUP explicitly as they are
+  // triggered anyway.
   if ((mask & (1 << kInEvent)) != 0) {
     pollfds->events |= POLLIN;
   }
   if ((mask & (1 << kOutEvent)) != 0) {
     pollfds->events |= POLLOUT;
   }
+  pollfds->events |= POLLRDHUP;
 }
 
 
@@ -213,27 +216,29 @@ void EventHandlerImplementation::HandleInterruptFd() {
 
 intptr_t EventHandlerImplementation::GetPollEvents(struct pollfd* pollfd) {
   intptr_t event_mask = 0;
-  /*
-   * We prioritize the events in the following order.
-   */
-  if ((pollfd->revents & POLLIN) != 0) {
-    if (FDUtils::AvailableBytes(pollfd->fd) != 0) {
-      event_mask = (1 << kInEvent);
-    } else if (((pollfd->revents & POLLHUP) != 0) ||
-               ((pollfd->revents & POLLRDHUP) != 0)) {
-      event_mask = (1 << kCloseEvent);
-    } else if ((pollfd->revents & POLLERR) != 0) {
-      event_mask = (1 << kErrorEvent);
-    } else {
-      /*
-       * Accept event.
-       */
-      event_mask = (1 << kInEvent);
+  if (IsListeningSocket(pollfd->fd)) {
+    // For listening sockets the POLLIN event indicate that there are
+    // connections ready for accept unless accompanied with one of the
+    // other flags.
+    if ((pollfd->revents & POLLIN) != 0) {
+      if ((pollfd->revents & POLLHUP) != 0) event_mask |= (1 << kCloseEvent);
+      if ((pollfd->revents & POLLERR) != 0) event_mask |= (1 << kErrorEvent);
+      if (event_mask == 0) event_mask |= (1 << kInEvent);
+    }
+  } else {
+    // Prioritize data events over close and error events.
+    if ((pollfd->revents & POLLIN) != 0) {
+      if (FDUtils::AvailableBytes(pollfd->fd) != 0) {
+        event_mask = (1 << kInEvent);
+      } else if (((pollfd->revents & POLLHUP) != 0) ||
+                 ((pollfd->revents & POLLRDHUP) != 0)) {
+        event_mask = (1 << kCloseEvent);
+      } else if ((pollfd->revents & POLLERR) != 0) {
+        event_mask = (1 << kErrorEvent);
+      }
     }
-  }
 
-  if ((pollfd->revents & POLLOUT) != 0) {
-    event_mask |= (1 << kOutEvent);
+    if ((pollfd->revents & POLLOUT) != 0) event_mask |= (1 << kOutEvent);
   }
 
   return event_mask;