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 #include "ipc/ipc_sync_message.h"
6
7 #include <stdint.h>
8
9 #include "base/atomic_sequence_num.h"
10 #include "base/logging.h"
11 #include "build/build_config.h"
12
13 namespace {
14
15 base::AtomicSequenceNumber g_next_id;
16
17 } // namespace
18
19 namespace IPC {
20
21 #define kSyncMessageHeaderSize 4
22
SyncMessage(int32_t routing_id,uint32_t type,PriorityValue priority,MessageReplyDeserializer * deserializer)23 SyncMessage::SyncMessage(int32_t routing_id,
24 uint32_t type,
25 PriorityValue priority,
26 MessageReplyDeserializer* deserializer)
27 : Message(routing_id, type, priority),
28 deserializer_(deserializer) {
29 set_sync();
30 set_unblock(true);
31
32 // Add synchronous message data before the message payload.
33 SyncHeader header;
34 header.message_id = g_next_id.GetNext();
35 WriteSyncHeader(this, header);
36 }
37
38 SyncMessage::~SyncMessage() = default;
39
GetReplyDeserializer()40 MessageReplyDeserializer* SyncMessage::GetReplyDeserializer() {
41 DCHECK(deserializer_.get());
42 return deserializer_.release();
43 }
44
IsMessageReplyTo(const Message & msg,int request_id)45 bool SyncMessage::IsMessageReplyTo(const Message& msg, int request_id) {
46 if (!msg.is_reply())
47 return false;
48
49 return GetMessageId(msg) == request_id;
50 }
51
GetDataIterator(const Message * msg)52 base::PickleIterator SyncMessage::GetDataIterator(const Message* msg) {
53 base::PickleIterator iter(*msg);
54 if (!iter.SkipBytes(kSyncMessageHeaderSize))
55 return base::PickleIterator();
56 else
57 return iter;
58 }
59
GetMessageId(const Message & msg)60 int SyncMessage::GetMessageId(const Message& msg) {
61 if (!msg.is_sync() && !msg.is_reply())
62 return 0;
63
64 SyncHeader header;
65 if (!ReadSyncHeader(msg, &header))
66 return 0;
67
68 return header.message_id;
69 }
70
GenerateReply(const Message * msg)71 Message* SyncMessage::GenerateReply(const Message* msg) {
72 DCHECK(msg->is_sync());
73
74 Message* reply = new Message(msg->routing_id(), IPC_REPLY_ID,
75 msg->priority());
76 reply->set_reply();
77
78 SyncHeader header;
79
80 // use the same message id, but this time reply bit is set
81 header.message_id = GetMessageId(*msg);
82 WriteSyncHeader(reply, header);
83
84 return reply;
85 }
86
ReadSyncHeader(const Message & msg,SyncHeader * header)87 bool SyncMessage::ReadSyncHeader(const Message& msg, SyncHeader* header) {
88 DCHECK(msg.is_sync() || msg.is_reply());
89
90 base::PickleIterator iter(msg);
91 bool result = iter.ReadInt(&header->message_id);
92 if (!result) {
93 NOTREACHED();
94 return false;
95 }
96
97 return true;
98 }
99
WriteSyncHeader(Message * msg,const SyncHeader & header)100 bool SyncMessage::WriteSyncHeader(Message* msg, const SyncHeader& header) {
101 DCHECK(msg->is_sync() || msg->is_reply());
102 DCHECK(msg->payload_size() == 0);
103 msg->WriteInt(header.message_id);
104
105 // Note: if you add anything here, you need to update kSyncMessageHeaderSize.
106 DCHECK(kSyncMessageHeaderSize == msg->payload_size());
107
108 return true;
109 }
110
111
SerializeOutputParameters(const Message & msg)112 bool MessageReplyDeserializer::SerializeOutputParameters(const Message& msg) {
113 return SerializeOutputParameters(msg, SyncMessage::GetDataIterator(&msg));
114 }
115
116 } // namespace IPC
117