Resize IPC input buffer to fit the next message.

ipc/ipc_message.h

 // 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.
 
 #ifndef IPC_IPC_MESSAGE_H_
 #define IPC_IPC_MESSAGE_H_
 
 #include <stdint.h>
 
 #include <string>
 
+#include "base/gtest_prod_util.h"
 #include "base/memory/ref_counted.h"
 #include "base/pickle.h"
 #include "base/trace_event/trace_event.h"
 #include "ipc/brokerable_attachment.h"
 #include "ipc/ipc_export.h"
 
 #if !defined(NDEBUG)
 #define IPC_MESSAGE_LOG_ENABLED
 #endif
 
@@ skipping 139 matching lines @@
     (obj->*func)(parameter);
     return true;
   }
 
   // Used for async messages with no parameters.
   static void Log(std::string* name, const Message* msg, std::string* l) {
   }
 
   // The static method FindNext() returns several pieces of information, which
   // are aggregated into an instance of this struct.
-  struct NextMessageInfo {
+  struct IPC_EXPORT NextMessageInfo {
     NextMessageInfo();
     ~NextMessageInfo();
 
+    // Total message size. Always valid if |message_found| is true.
+    // If |message_found| is false but we could determine message size
+    // from the header, this field is non-zero. Otherwise it's zero.
+    size_t message_size;
     // Whether an entire message was found in the given memory range.
     bool message_found;
     // Only filled in if |message_found| is true.
     // The start address is passed into FindNext() by the caller, so isn't
     // repeated in this struct. The end address of the pickle should be used to
     // construct a base::Pickle.
     const char* pickle_end;
     // Only filled in if |message_found| is true.
     // The end address of the message should be used to determine the start
     // address of the next message.
@@ skipping 115 matching lines @@
   // a valid value for every message dispatched to listeners.
   base::ProcessId sender_pid_;
 
 #ifdef IPC_MESSAGE_LOG_ENABLED
   // Used for logging.
   mutable int64_t received_time_;
   mutable std::string output_params_;
   mutable LogData* log_data_;
   mutable bool dont_log_;
 #endif
+
+  FRIEND_TEST_ALL_PREFIXES(IPCMessageTest, FindNext);
+  FRIEND_TEST_ALL_PREFIXES(IPCMessageTest, FindNextOverflow);
 };
 
 //------------------------------------------------------------------------------
 
 }  // namespace IPC
 
 enum SpecialRoutingIDs {
   // indicates that we don't have a routing ID yet.
   MSG_ROUTING_NONE = -2,
 
   // indicates a general message not sent to a particular tab.
   MSG_ROUTING_CONTROL = INT32_MAX,
 };
 
 #define IPC_REPLY_ID 0xFFFFFFF0  // Special message id for replies
 #define IPC_LOGGING_ID 0xFFFFFFF1  // Special message id for logging
 
 #endif  // IPC_IPC_MESSAGE_H_