ipc/glue/RawShmem.cpp

   1 /* -*- Mode: C++; tab-width: 4; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
   2 /* This Source Code Form is subject to the terms of the Mozilla Public
   3  * License, v. 2.0. If a copy of the MPL was not distributed with this
   4  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
   5
   6 #include "RawShmem.h"
   7 #include "mozilla/ipc/ProtocolUtils.h"
   8
   9 namespace mozilla::ipc {
  10
  11 UnsafeSharedMemoryHandle::UnsafeSharedMemoryHandle()
  12     : mHandle(ipc::SharedMemory::NULLHandle()), mSize(0) {}
  13
  14 UnsafeSharedMemoryHandle::UnsafeSharedMemoryHandle(
  15     UnsafeSharedMemoryHandle&& aOther) noexcept
  16     : mHandle(std::move(aOther.mHandle)), mSize(aOther.mSize) {
  17   aOther.mHandle = ipc::SharedMemory::NULLHandle();
  18   aOther.mSize = 0;
  19 }
  20
  21 UnsafeSharedMemoryHandle& UnsafeSharedMemoryHandle::operator=(
  22     UnsafeSharedMemoryHandle&& aOther) noexcept {
  23   if (this == &aOther) {
  24     return *this;
  25   }
  26
  27   mHandle = std::move(aOther.mHandle);
  28   mSize = aOther.mSize;
  29   aOther.mHandle = ipc::SharedMemory::NULLHandle();
  30   aOther.mSize = 0;
  31   return *this;
  32 }
  33
  34 Maybe<std::pair<UnsafeSharedMemoryHandle, WritableSharedMemoryMapping>>
  35 UnsafeSharedMemoryHandle::CreateAndMap(size_t aSize) {
  36   if (aSize == 0) {
  37     return Some(std::make_pair(UnsafeSharedMemoryHandle(),
  38                                WritableSharedMemoryMapping()));
  39   }
  40
  41   RefPtr<ipc::SharedMemory> shm = MakeAndAddRef<ipc::SharedMemory>();
  42   if (NS_WARN_IF(!shm->Create(aSize)) || NS_WARN_IF(!shm->Map(aSize))) {
  43     return Nothing();
  44   }
  45
  46   auto handle = shm->TakeHandle();
  47
  48   auto size = shm->Size();
  49
  50   return Some(std::make_pair(UnsafeSharedMemoryHandle(std::move(handle), size),
  51                              WritableSharedMemoryMapping(std::move(shm))));
  52 }
  53
  54 WritableSharedMemoryMapping::WritableSharedMemoryMapping(
  55     RefPtr<ipc::SharedMemory>&& aRef)
  56     : mRef(aRef) {}
  57
  58 Maybe<WritableSharedMemoryMapping> WritableSharedMemoryMapping::Open(
  59     UnsafeSharedMemoryHandle aHandle) {
  60   if (aHandle.mSize == 0) {
  61     return Some(WritableSharedMemoryMapping(nullptr));
  62   }
  63
  64   RefPtr<ipc::SharedMemory> shm = MakeAndAddRef<ipc::SharedMemory>();
  65   if (NS_WARN_IF(!shm->SetHandle(std::move(aHandle.mHandle),
  66                                  ipc::SharedMemory::RightsReadWrite)) ||
  67       NS_WARN_IF(!shm->Map(aHandle.mSize))) {
  68     return Nothing();
  69   }
  70
  71   shm->CloseHandle();
  72
  73   return Some(WritableSharedMemoryMapping(std::move(shm)));
  74 }
  75
  76 size_t WritableSharedMemoryMapping::Size() const {
  77   if (!mRef) {
  78     return 0;
  79   }
  80
  81   return mRef->Size();
  82 }
  83
  84 Span<uint8_t> WritableSharedMemoryMapping::Bytes() {
  85   if (!mRef) {
  86     return Span<uint8_t>();
  87   }
  88
  89   uint8_t* mem = static_cast<uint8_t*>(mRef->Memory());
  90   return Span(mem, mRef->Size());
  91 }
  92
  93 }  // namespace mozilla::ipc
  94
  95 namespace IPC {
  96 auto ParamTraits<mozilla::ipc::UnsafeSharedMemoryHandle>::Write(
  97     IPC::MessageWriter* aWriter, paramType&& aVar) -> void {
  98   IPC::WriteParam(aWriter, std::move(aVar.mHandle));
  99   IPC::WriteParam(aWriter, aVar.mSize);
 100 }
 101
 102 auto ParamTraits<mozilla::ipc::UnsafeSharedMemoryHandle>::Read(
 103     IPC::MessageReader* aReader, paramType* aVar) -> bool {
 104   return IPC::ReadParam(aReader, &aVar->mHandle) &&
 105          IPC::ReadParam(aReader, &aVar->mSize);
 106 }
 107
 108 }  // namespace IPC