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1 // Copyright 2014 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 MOJO_PUBLIC_CPP_BINDINGS_MESSAGE_H_ | |
6 #define MOJO_PUBLIC_CPP_BINDINGS_MESSAGE_H_ | |
7 | |
8 #include <vector> | |
9 | |
10 #include "mojo/public/cpp/bindings/lib/message_internal.h" | |
11 #include "mojo/public/cpp/environment/logging.h" | |
12 | |
13 namespace mojo { | |
14 | |
15 // Message is a holder for the data and handles to be sent over a MessagePipe. | |
16 // Message owns its data and handles, but a consumer of Message is free to | |
17 // mutate the data and handles. The message's data is comprised of a header | |
18 // followed by payload. | |
19 class Message { | |
20 public: | |
21 Message(); | |
22 ~Message(); | |
23 | |
24 // These may only be called on a newly created Message object. | |
25 void AllocUninitializedData(uint32_t num_bytes); | |
26 void AdoptData(uint32_t num_bytes, internal::MessageData* data); | |
27 | |
28 // Swaps data and handles between this Message and another. | |
29 void Swap(Message* other); | |
30 | |
31 uint32_t data_num_bytes() const { return data_num_bytes_; } | |
32 | |
33 // Access the raw bytes of the message. | |
34 const uint8_t* data() const { | |
35 return reinterpret_cast<const uint8_t*>(data_); | |
36 } | |
37 uint8_t* mutable_data() { return reinterpret_cast<uint8_t*>(data_); } | |
38 | |
39 // Access the header. | |
40 const internal::MessageHeader* header() const { return &data_->header; } | |
41 | |
42 uint32_t name() const { return data_->header.name; } | |
43 bool has_flag(uint32_t flag) const { return !!(data_->header.flags & flag); } | |
44 | |
45 // Access the request_id field (if present). | |
46 bool has_request_id() const { return data_->header.num_fields >= 3; } | |
47 uint64_t request_id() const { | |
48 MOJO_DCHECK(has_request_id()); | |
49 return static_cast<const internal::MessageHeaderWithRequestID*>( | |
50 &data_->header)->request_id; | |
51 } | |
52 void set_request_id(uint64_t request_id) { | |
53 MOJO_DCHECK(has_request_id()); | |
54 static_cast<internal::MessageHeaderWithRequestID*>(&data_->header) | |
55 ->request_id = request_id; | |
56 } | |
57 | |
58 // Access the payload. | |
59 const uint8_t* payload() const { | |
60 return reinterpret_cast<const uint8_t*>(data_) + data_->header.num_bytes; | |
61 } | |
62 uint8_t* mutable_payload() { | |
63 return reinterpret_cast<uint8_t*>(data_) + data_->header.num_bytes; | |
64 } | |
65 uint32_t payload_num_bytes() const { | |
66 MOJO_DCHECK(data_num_bytes_ >= data_->header.num_bytes); | |
67 return data_num_bytes_ - data_->header.num_bytes; | |
68 } | |
69 | |
70 // Access the handles. | |
71 const std::vector<Handle>* handles() const { return &handles_; } | |
72 std::vector<Handle>* mutable_handles() { return &handles_; } | |
73 | |
74 private: | |
75 uint32_t data_num_bytes_; | |
76 internal::MessageData* data_; // Heap-allocated using malloc. | |
77 std::vector<Handle> handles_; | |
78 | |
79 MOJO_DISALLOW_COPY_AND_ASSIGN(Message); | |
80 }; | |
81 | |
82 class MessageReceiver { | |
83 public: | |
84 virtual ~MessageReceiver() {} | |
85 | |
86 // The receiver may mutate the given message. Returns true if the message | |
87 // was accepted and false otherwise, indicating that the message was invalid | |
88 // or malformed. | |
89 virtual bool Accept(Message* message) MOJO_WARN_UNUSED_RESULT = 0; | |
90 }; | |
91 | |
92 class MessageReceiverWithResponder : public MessageReceiver { | |
93 public: | |
94 ~MessageReceiverWithResponder() override {} | |
95 | |
96 // A variant on Accept that registers a MessageReceiver (known as the | |
97 // responder) to handle the response message generated from the given | |
98 // message. The responder's Accept method may be called during | |
99 // AcceptWithResponder or some time after its return. | |
100 // | |
101 // NOTE: Upon returning true, AcceptWithResponder assumes ownership of | |
102 // |responder| and will delete it after calling |responder->Accept| or upon | |
103 // its own destruction. | |
104 // | |
105 virtual bool AcceptWithResponder(Message* message, MessageReceiver* responder) | |
106 MOJO_WARN_UNUSED_RESULT = 0; | |
107 }; | |
108 | |
109 // Read a single message from the pipe and dispatch to the given receiver. The | |
110 // receiver may be null, in which case the message is simply discarded. | |
111 // Returns MOJO_RESULT_SHOULD_WAIT if the caller should wait on the handle to | |
112 // become readable. Returns MOJO_RESULT_OK if a message was dispatched and | |
113 // otherwise returns an error code if something went wrong. | |
114 // | |
115 // NOTE: The message hasn't been validated and may be malformed! | |
116 MojoResult ReadAndDispatchMessage(MessagePipeHandle handle, | |
117 MessageReceiver* receiver, | |
118 bool* receiver_result); | |
119 | |
120 } // namespace mojo | |
121 | |
122 #endif // MOJO_PUBLIC_CPP_BINDINGS_MESSAGE_H_ | |
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