summaryrefslogtreecommitdiffstats
path: root/ipc/mscom/COMPtrHolder.h
blob: 88d372a27043ec125b4b6d73ffa6df30e82dc421 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */

#ifndef mozilla_mscom_COMPtrHolder_h
#define mozilla_mscom_COMPtrHolder_h

#include "mozilla/Attributes.h"
#include "mozilla/Move.h"
#include "mozilla/mscom/ProxyStream.h"
#include "mozilla/mscom/Ptr.h"

namespace mozilla {
namespace mscom {

template<typename Interface, const IID& _IID>
class COMPtrHolder
{
public:
  typedef ProxyUniquePtr<Interface> COMPtrType;
  typedef COMPtrHolder<Interface, _IID> ThisType;

  COMPtrHolder() {}

  MOZ_IMPLICIT COMPtrHolder(decltype(nullptr))
  {
  }

  explicit COMPtrHolder(COMPtrType&& aPtr)
    : mPtr(Forward<COMPtrType>(aPtr))
  {
  }

  Interface* Get() const
  {
    return mPtr.get();
  }

  MOZ_MUST_USE Interface* Release()
  {
    return mPtr.release();
  }

  void Set(COMPtrType&& aPtr)
  {
    mPtr = Forward<COMPtrType>(aPtr);
  }

  COMPtrHolder(const COMPtrHolder& aOther) = delete;

  COMPtrHolder(COMPtrHolder&& aOther)
    : mPtr(Move(aOther.mPtr))
  {
  }

  // COMPtrHolder is eventually added as a member of a struct that is declared
  // in IPDL. The generated C++ code for that IPDL struct includes copy
  // constructors and assignment operators that assume that all members are
  // copyable. I don't think that those copy constructors and operator= are
  // actually used by any generated code, but they are made available. Since no
  // move semantics are available, this terrible hack makes COMPtrHolder build
  // when used as a member of an IPDL struct.
  ThisType& operator=(const ThisType& aOther)
  {
    Set(Move(aOther.mPtr));
    return *this;
  }

  ThisType& operator=(ThisType&& aOther)
  {
    Set(Move(aOther.mPtr));
    return *this;
  }

  bool operator==(const ThisType& aOther) const
  {
    return mPtr == aOther.mPtr;
  }

  bool IsNull() const
  {
    return !mPtr;
  }

private:
  // This is mutable to facilitate the above operator= hack
  mutable COMPtrType mPtr;
};

} // namespace mscom
} // namespace mozilla

namespace IPC {

template<typename Interface, const IID& _IID>
struct ParamTraits<mozilla::mscom::COMPtrHolder<Interface, _IID>>
{
  typedef mozilla::mscom::COMPtrHolder<Interface, _IID> paramType;

  static void Write(Message* aMsg, const paramType& aParam)
  {
    mozilla::mscom::ProxyStream proxyStream(_IID, aParam.Get());
    int bufLen;
    const BYTE* buf = proxyStream.GetBuffer(bufLen);
    MOZ_ASSERT(buf || !bufLen);
    aMsg->WriteInt(bufLen);
    aMsg->WriteBytes(reinterpret_cast<const char*>(buf), bufLen);
  }

  static bool Read(const Message* aMsg, PickleIterator* aIter, paramType* aResult)
  {
    int length;
    if (!aMsg->ReadLength(aIter, &length)) {
      return false;
    }

    mozilla::UniquePtr<BYTE[]> buf;
    if (length) {
      buf = mozilla::MakeUnique<BYTE[]>(length);
      if (!aMsg->ReadBytesInto(aIter, buf.get(), length)) {
        return false;
      }
    }

    mozilla::mscom::ProxyStream proxyStream(buf.get(), length);
    if (!proxyStream.IsValid()) {
      return false;
    }
    Interface* rawInterface = nullptr;
    if (!proxyStream.GetInterface(_IID, (void**)&rawInterface)) {
      return false;
    }
    typename paramType::COMPtrType ptr(rawInterface);
    aResult->Set(mozilla::Move(ptr));
    return true;
  }
};

} // namespace IPC

#endif // mozilla_mscom_COMPtrHolder_h