ipc: Update Message::FindNext to parse brokered attachments.

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 <string>
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "base/pickle.h"
 #include "base/trace_event/trace_event.h"
 #include "ipc/attachment_broker.h"
+#include "ipc/brokerable_attachment.h"
 #include "ipc/ipc_export.h"
 
 #if !defined(NDEBUG)
 #define IPC_MESSAGE_LOG_ENABLED
 #endif
 
 namespace IPC {
 
 namespace internal {
 class ChannelReader;
@@ skipping 133 matching lines @@
   static bool Dispatch(const Message* msg, T* obj, S* sender, P* parameter,
                        void (T::*func)(P*)) {
     (obj->*func)(parameter);
     return true;
   }
 
   // Used for async messages with no parameters.
   static void Log(std::string* name, const Message* msg, std::string* l) {
   }
 
-  // Find the end of the message data that starts at range_start.  Returns NULL
-  // if the entire message is not found in the given data range.
-  static const char* FindNext(const char* range_start, const char* range_end) {
-    return base::Pickle::FindNext(sizeof(Header), range_start, range_end);
-  }
+  // The static method FindNext() returns several pieces of information, which
+  // are aggregated into an instance of this struct.

[Tom Sepez, 2015/09/01 18:01:54]

nit: this may be complex enough to warrant being a class with protected members.
 Your call.

[erikchen, 2015/09/04 02:13:39]

This is just a wrapper around several different pieces of information being
returned from a function. Making it a class and adding accessors adds
unnecessary complexity.

+  struct NextMessageInfo {
+    NextMessageInfo();
+    ~NextMessageInfo();
+    // Whether an entire message was found in the given memory range.
+    bool message_found;
+    // The parser encountered an unrecoverable error. This will always be false
+    // if |message_found| is true.
+    bool parsing_error;
+    // 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.
+    const char* message_end;
+    // If the message has brokerable attachments, this vector will contain the
+    // ids of the brokerable attachments. The caller of FindNext() is
+    // responsible for adding the attachments to the message.
+    std::vector<BrokerableAttachment::AttachmentId> attachment_ids;
+  };
+
+  static NextMessageInfo FindNext(const char* range_start,
+                                  const char* range_end);
 
   // WriteAttachment appends |attachment| to the end of the set. It returns
   // false iff the set is full.
   bool WriteAttachment(scoped_refptr<MessageAttachment> attachment);
   // ReadAttachment parses an attachment given the parsing state |iter| and
   // writes it to |*attachment|. It returns true on success.
   bool ReadAttachment(base::PickleIterator* iter,
                       scoped_refptr<MessageAttachment>* attachment) const;
   // Returns true if there are any attachment in this message.
   bool HasAttachments() const;
@@ skipping 101 matching lines @@
   MSG_ROUTING_NONE = -2,
 
   // indicates a general message not sent to a particular tab.
   MSG_ROUTING_CONTROL = kint32max,
 };
 
 #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_