1 // Copyright 2013 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 "mojo/system/message_in_transit.h"
6
7 #include <stdlib.h>
8 #include <string.h>
9
10 #include <new>
11
12 #include "base/basictypes.h"
13 #include "base/compiler_specific.h"
14 #include "base/logging.h"
15 #include "mojo/system/constants.h"
16
17 namespace mojo {
18 namespace system {
19
20 // Avoid dangerous situations, but making sure that the size of the "header" +
21 // the size of the data fits into a 31-bit number.
22 COMPILE_ASSERT(static_cast<uint64_t>(sizeof(MessageInTransit)) +
23 kMaxMessageNumBytes <= 0x7fffffff,
24 kMaxMessageNumBytes_too_big);
25
26 COMPILE_ASSERT(sizeof(MessageInTransit) %
27 MessageInTransit::kMessageAlignment == 0,
28 sizeof_MessageInTransit_not_a_multiple_of_alignment);
29
30 STATIC_CONST_MEMBER_DEFINITION const MessageInTransit::Type
31 MessageInTransit::kTypeMessagePipeEndpoint;
32 STATIC_CONST_MEMBER_DEFINITION const MessageInTransit::Type
33 MessageInTransit::kTypeMessagePipe;
34 STATIC_CONST_MEMBER_DEFINITION const MessageInTransit::Type
35 MessageInTransit::TYPE_CHANNEL;
36 STATIC_CONST_MEMBER_DEFINITION const MessageInTransit::Subtype
37 MessageInTransit::kSubtypeMessagePipeEndpointData;
38 STATIC_CONST_MEMBER_DEFINITION const MessageInTransit::Subtype
39 MessageInTransit::kSubtypeMessagePipePeerClosed;
40 STATIC_CONST_MEMBER_DEFINITION const MessageInTransit::EndpointId
41 MessageInTransit::kInvalidEndpointId;
42 STATIC_CONST_MEMBER_DEFINITION const size_t MessageInTransit::kMessageAlignment;
43
44 // static
Create(Type type,Subtype subtype,const void * bytes,uint32_t num_bytes)45 MessageInTransit* MessageInTransit::Create(Type type,
46 Subtype subtype,
47 const void* bytes,
48 uint32_t num_bytes) {
49 const size_t size_with_header = sizeof(MessageInTransit) + num_bytes;
50 const size_t size_with_header_and_padding =
51 RoundUpMessageAlignment(size_with_header);
52
53 char* buffer = static_cast<char*>(malloc(size_with_header_and_padding));
54 DCHECK_EQ(reinterpret_cast<size_t>(buffer) %
55 MessageInTransit::kMessageAlignment, 0u);
56
57 // The buffer consists of the header (a |MessageInTransit|, constructed using
58 // a placement new), followed by the data, followed by padding (of zeros).
59 MessageInTransit* rv =
60 new (buffer) MessageInTransit(num_bytes, type, subtype);
61 memcpy(buffer + sizeof(MessageInTransit), bytes, num_bytes);
62 memset(buffer + size_with_header, 0,
63 size_with_header_and_padding - size_with_header);
64 return rv;
65 }
66
67 } // namespace system
68 } // namespace mojo
69