1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
2 // Use of this source code is governed by a BSD-style license that can be
3 // found in the LICENSE file.
4 
5 #ifndef IPC_IPC_SYNC_MESSAGE_H_
6 #define IPC_IPC_SYNC_MESSAGE_H_
7 
8 #include <stdint.h>
9 
10 #if defined(OS_WIN)
11 #include <windows.h>
12 #endif
13 
14 #include <memory>
15 #include <string>
16 
17 #include "build/build_config.h"
18 #include "ipc/ipc_message.h"
19 
20 namespace IPC {
21 
22 class MessageReplyDeserializer;
23 class MojoEvent;
24 
25 class IPC_EXPORT SyncMessage : public Message {
26  public:
27   SyncMessage(int32_t routing_id,
28               uint32_t type,
29               PriorityValue priority,
30               MessageReplyDeserializer* deserializer);
31   ~SyncMessage() override;
32 
33   // Call this to get a deserializer for the output parameters.
34   // Note that this can only be called once, and the caller is responsible
35   // for deleting the deserializer when they're done.
36   MessageReplyDeserializer* GetReplyDeserializer();
37 
38   // If this message can cause the receiver to block while waiting for user
39   // input (i.e. by calling MessageBox), then the caller needs to pump window
40   // messages and dispatch asynchronous messages while waiting for the reply.
41   // This call enables message pumping behavior while waiting for a reply to
42   // this message.
EnableMessagePumping()43   void EnableMessagePumping() {
44     header()->flags |= PUMPING_MSGS_BIT;
45   }
46 
47   // Indicates whether window messages should be pumped while waiting for a
48   // reply to this message.
ShouldPumpMessages()49   bool ShouldPumpMessages() const {
50     return (header()->flags & PUMPING_MSGS_BIT) != 0;
51   }
52 
53   // Returns true if the message is a reply to the given request id.
54   static bool IsMessageReplyTo(const Message& msg, int request_id);
55 
56   // Given a reply message, returns an iterator to the beginning of the data
57   // (i.e. skips over the synchronous specific data).
58   static base::PickleIterator GetDataIterator(const Message* msg);
59 
60   // Given a synchronous message (or its reply), returns its id.
61   static int GetMessageId(const Message& msg);
62 
63   // Generates a reply message to the given message.
64   static Message* GenerateReply(const Message* msg);
65 
66  private:
67   struct SyncHeader {
68     // unique ID (unique per sender)
69     int message_id;
70   };
71 
72   static bool ReadSyncHeader(const Message& msg, SyncHeader* header);
73   static bool WriteSyncHeader(Message* msg, const SyncHeader& header);
74 
75   std::unique_ptr<MessageReplyDeserializer> deserializer_;
76 };
77 
78 // Used to deserialize parameters from a reply to a synchronous message
79 class IPC_EXPORT MessageReplyDeserializer {
80  public:
~MessageReplyDeserializer()81   virtual ~MessageReplyDeserializer() {}
82   bool SerializeOutputParameters(const Message& msg);
83  private:
84   // Derived classes need to implement this, using the given iterator (which
85   // is skipped past the header for synchronous messages).
86   virtual bool SerializeOutputParameters(const Message& msg,
87                                          base::PickleIterator iter) = 0;
88 };
89 
90 // When sending a synchronous message, this structure contains an object
91 // that knows how to deserialize the response.
92 struct PendingSyncMsg {
PendingSyncMsgPendingSyncMsg93   PendingSyncMsg(int id, MessageReplyDeserializer* d, MojoEvent* e)
94       : id(id), deserializer(d), done_event(e), send_result(false) { }
95 
96   int id;
97   MessageReplyDeserializer* deserializer;
98   MojoEvent* done_event;
99   bool send_result;
100 };
101 
102 }  // namespace IPC
103 
104 #endif  // IPC_IPC_SYNC_MESSAGE_H_
105