Use the thread safe gethostbyname function on Linux

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 <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 #include <unistd.h>
 
 #include "bin/fdutils.h"
 #include "bin/socket.h"
 
 
 bool Socket::Initialize() {
   // Nothing to do on Linux.
   return true;
 }
 
 
 intptr_t Socket::CreateConnect(const char* host, const intptr_t port) {
   intptr_t fd;
-  struct hostent* server;
+  struct hostent server;
   struct sockaddr_in server_address;
 
   fd = TEMP_FAILURE_RETRY(socket(AF_INET, SOCK_STREAM, 0));
   if (fd < 0) {
     fprintf(stderr, "Error CreateConnect: %s\n", strerror(errno));
     return -1;
   }
 
   FDUtils::SetNonBlocking(fd);
 
-  server = gethostbyname(host);
-  if (server == NULL) {
+  static const size_t kTempBufSize = 1024;
+  char temp_buf[kTempBufSize];
+  struct hostent *unused;
+  int err;
+  if (gethostbyname_r(
+          host, &server, temp_buf, kTempBufSize, &unused, &err) != 0) {
     TEMP_FAILURE_RETRY(close(fd));
     fprintf(stderr, "Error CreateConnect: %s\n", strerror(errno));
     return -1;
   }
 
   server_address.sin_family = AF_INET;
   server_address.sin_port = htons(port);
-  bcopy(server->h_addr, &server_address.sin_addr.s_addr, server->h_length);
+  bcopy(server.h_addr, &server_address.sin_addr.s_addr, server.h_length);
   memset(&server_address.sin_zero, 0, sizeof(server_address.sin_zero));
   intptr_t result = TEMP_FAILURE_RETRY(
       connect(fd,
               reinterpret_cast<struct sockaddr *>(&server_address),
               sizeof(server_address)));
   if (result == 0 || errno == EINPROGRESS) {
     return fd;
   }
   return -1;
 }
@@ skipping 182 matching lines @@
       // 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;
 }