ipc/glue/SharedMemory.h
author Chris Jones <jones.chris.g@gmail.com>
Tue, 26 Jan 2010 22:56:11 -0600
changeset 46612 fffccafd827fc2cce40c6185c461cbcc4dce0683
parent 36152 5ffc5409203c649967a622154eb7437eeb10fdd8
child 40908 4116478e20022a97885b9eacbbb70e73e28827c6
permissions -rw-r--r--
Bug 540111, part 2: Subsume direct calls to manager->Dealloc*() into RemoveManagee(). r=bent

/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
 * vim: sw=2 ts=8 et :
 */
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 * The Original Code is Mozilla IPC.
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#ifndef mozilla_ipc_SharedMemory_h
#define mozilla_ipc_SharedMemory_h

#include "base/shared_memory.h"

#include "nsDebug.h"

//
// This is a low-level wrapper around platform shared memory.  Don't
// use it directly; use Shmem allocated through IPDL interfaces.
//
namespace {
enum Rights {
  RightsNone = 0,
  RightsRead = 1 << 0,
  RightsWrite = 1 << 1
};
}

namespace mozilla {
namespace ipc {

class SharedMemory : public base::SharedMemory
{
public:
  typedef base::SharedMemoryHandle SharedMemoryHandle;

  SharedMemory() :
    base::SharedMemory(),
    mSize(0)
  {
  }

  SharedMemory(const SharedMemoryHandle& aHandle) :
    base::SharedMemory(aHandle, false),
    mSize(0)
  {
  }

  bool Map(size_t nBytes)
  {
    bool ok = base::SharedMemory::Map(nBytes);
    if (ok)
      mSize = nBytes;
    return ok;
  }

  size_t Size()
  {
    return mSize;
  }

  void
  Protect(char* aAddr, size_t aSize, int aRights)
  {
    char* memStart = reinterpret_cast<char*>(memory());
    if (!memStart)
      NS_RUNTIMEABORT("SharedMemory region points at NULL!");
    char* memEnd = memStart + Size();

    char* protStart = aAddr;
    if (!protStart)
      NS_RUNTIMEABORT("trying to Protect() a NULL region!");
    char* protEnd = protStart + aSize;

    if (!(memStart <= protStart
          && protEnd <= memEnd))
      NS_RUNTIMEABORT("attempt to Protect() a region outside this SharedMemory");

    // checks alignment etc.
    SystemProtect(aAddr, aSize, aRights);
  }

  static void SystemProtect(char* aAddr, size_t aSize, int aRights);
  static size_t SystemPageSize();

private:
  // NB: we have to track this because shared_memory_win.cc doesn't
  size_t mSize;
};

} // namespace ipc
} // namespace mozilla


#endif // ifndef mozilla_ipc_SharedMemory_h