Treat EAGAIN/EWOULDBLOCK as requests for retry on socket accept.

runtime/bin/socket_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 <arpa/inet.h>
 #include <errno.h>
 #include <netdb.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
@@ skipping 170 matching lines @@
 
   if (TEMP_FAILURE_RETRY(listen(fd, backlog)) != 0) {
     fprintf(stderr, "Error Listen: %s\n", strerror(errno));
     return -1;
   }
 
   FDUtils::SetNonBlocking(fd);
   return fd;
 }
 
+
+static bool IsTemporaryAcceptError(int error) {
+  // On Linux a number of protocol errors should be treated as EAGAIN.
+  // These are the ones for TCP/IP.
+  return (error == EAGAIN) || (error == ENETDOWN) || (error == EPROTO) ||
+      (error == ENOPROTOOPT) || (error == EHOSTDOWN) || (error == ENONET) ||
+      (error == EHOSTUNREACH) || (error == EOPNOTSUPP) ||
+      (error == ENETUNREACH);
+}
+
+
 intptr_t ServerSocket::Accept(intptr_t fd) {
   intptr_t socket;
   struct sockaddr clientaddr;
   socklen_t addrlen = sizeof(clientaddr);
   socket = TEMP_FAILURE_RETRY(accept(fd, &clientaddr, &addrlen));
-  if (socket < 0) {
-    fprintf(stderr, "Error Accept: %s\n", strerror(errno));
+  if (socket == -1) {
+    if (IsTemporaryAcceptError(errno)) {
+      // We need to signal to the caller that this is actually not an
+      // error. We got woken up from the poll on the listening socket,
+      // but there is no connection ready to be accepted.
+      ASSERT(kTemporaryFailure != -1);
+      socket = kTemporaryFailure;
+    }
   } else {
     FDUtils::SetNonBlocking(socket);
   }
   return socket;
 }