Support HTTP test-server based net unit tests on Android.

tools/android/forwarder2/command.cc

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "tools/android/forwarder2/command.h"
 
 #include <errno.h>
 #include <stdio.h>
 #include <stdlib.h>
 #include <string.h>
 
 #include "base/logging.h"
+#include "base/safe_strerror_posix.h"
 #include "base/string_number_conversions.h"
 #include "base/string_piece.h"
 #include "tools/android/forwarder2/socket.h"
 
 using base::StringPiece;
 
 namespace {
 
 
 // Command format:
@@ skipping 16 matching lines @@
 
 namespace forwarder2 {
 
 bool ReadCommand(Socket* socket,
                  int* port_out,
                  command::Type* command_type_out) {
   char command_buffer[kCommandStringSize + 1];
   // To make logging easier.
   command_buffer[kCommandStringSize] = '\0';
 
-  if (socket->ReadNumBytes(command_buffer, kCommandStringSize) !=
-      kCommandStringSize) {
-    LOG(ERROR) << "Not enough data received from the socket.";
+  int bytes_read = socket->ReadNumBytes(command_buffer, kCommandStringSize);
+  if (bytes_read != kCommandStringSize) {
+    if (bytes_read < 0)
+      LOG(ERROR) << "Read() error: " << safe_strerror(errno);
+    else if (!bytes_read)
+      LOG(ERROR) << "Read() error, endpoint was unexpectedly closed.";
+    else
+      LOG(ERROR) << "Read() error, not enough data received from the socket.";
     return false;
   }
 
   StringPiece port_str(command_buffer, kPortStringSize);
   if (!StringToInt(port_str, port_out)) {
     LOG(ERROR) << "Could not parse the command port string: "
                << port_str;
     return false;
   }
 
@@ skipping 19 matching lines @@
 
 bool ReceivedCommand(command::Type command, Socket* socket) {
   int port;
   command::Type received_command;
   if (!ReadCommand(socket, &port, &received_command))
     return false;
   return received_command == command;
 }
 
 }  // namespace forwarder