Extend dart:io error handling to all socket functions

runtime/bin/eventhandler_linux.cc

 // Copyright (c) 2012, the Dart project authors.  Please see the AUTHORS file
 // for details. All rights reserved. Use of this source code is governed by a
 // BSD-style license that can be found in the LICENSE file.
 
 #include "bin/eventhandler.h"
 
 #include <errno.h>
 #include <pthread.h>
 #include <stdio.h>
 #include <string.h>
@@ skipping 243 matching lines @@
     if ((events & EPOLLIN) != 0) {
       if ((events & EPOLLHUP) != 0) event_mask |= (1 << kCloseEvent);
       if ((events & EPOLLERR) != 0) event_mask |= (1 << kErrorEvent);
       if (event_mask == 0) event_mask |= (1 << kInEvent);
     }
   } else {
     // Prioritize data events over close and error events.
     if ((events & EPOLLIN) != 0) {
       if (FDUtils::AvailableBytes(sd->fd()) != 0) {
         event_mask = (1 << kInEvent);
-      } else if (((events & EPOLLHUP) != 0)) {
-        event_mask = (1 << kCloseEvent);
+      } else if ((events & EPOLLHUP) != 0) {
+        // If both EPOLLHUP and EPOLLERR are reported treat it as an
+        // error.
+        if ((events & EPOLLERR) != 0) {
+          event_mask = (1 << kErrorEvent);
+        } else {
+          event_mask = (1 << kCloseEvent);
+        }
         sd->MarkClosedRead();
       } else if ((events & EPOLLERR) != 0) {
         event_mask = (1 << kErrorEvent);
       } else {
         if (sd->IsPipe()) {
           // When reading from stdin (either from a terminal or piped
           // input) treat EPOLLIN with 0 available bytes as
           // end-of-file.
           if (sd->fd() == STDIN_FILENO) {
             event_mask = (1 << kCloseEvent);
@@ skipping 127 matching lines @@
 void* EventHandlerImplementation::GetHashmapKeyFromFd(intptr_t fd) {
   // The hashmap does not support keys with value 0.
   return reinterpret_cast<void*>(fd + 1);
 }
 
 
 uint32_t EventHandlerImplementation::GetHashmapHashFromFd(intptr_t fd) {
   // The hashmap does not support keys with value 0.
   return dart::Utils::WordHash(fd + 1);
 }