gecko/ipc/glue/SharedMemory.h

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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* vim: sw=2 ts=8 et :
*/
/* ***** BEGIN LICENSE BLOCK *****
* Version: MPL 1.1/GPL 2.0/LGPL 2.1
*
* The contents of this file are subject to the Mozilla Public License Version
* 1.1 (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
* http://www.mozilla.org/MPL/
*
* Software distributed under the License is distributed on an "AS IS" basis,
* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
* for the specific language governing rights and limitations under the
* License.
*
* The Original Code is Mozilla IPC.
*
* The Initial Developer of the Original Code is
* The Mozilla Foundation
* Portions created by the Initial Developer are Copyright (C) 2009-2010
* the Initial Developer. All Rights Reserved.
*
* Contributor(s):
*
* Alternatively, the contents of this file may be used under the terms of
* either the GNU General Public License Version 2 or later (the "GPL"), or
* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
* in which case the provisions of the GPL or the LGPL are applicable instead
* of those above. If you wish to allow use of your version of this file only
* under the terms of either the GPL or the LGPL, and not to allow others to
* use your version of this file under the terms of the MPL, indicate your
* decision by deleting the provisions above and replace them with the notice
* and other provisions required by the GPL or the LGPL. If you do not delete
* the provisions above, a recipient may use your version of this file under
* the terms of any one of the MPL, the GPL or the LGPL.
*
* ***** END LICENSE BLOCK ***** */
#ifndef mozilla_ipc_SharedMemory_h
#define mozilla_ipc_SharedMemory_h
#include "nsDebug.h"
#include "nsISupportsImpl.h" // NS_INLINE_DECL_REFCOUNTING
//
// 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:
enum SharedMemoryType {
TYPE_BASIC,
TYPE_SYSV,
TYPE_UNKNOWN
};
virtual ~SharedMemory() { Unmapped(); Destroyed(); }
size_t Size() const { return mMappedSize; }
virtual void* memory() const = 0;
virtual bool Create(size_t size) = 0;
virtual bool Map(size_t nBytes) = 0;
virtual SharedMemoryType Type() const = 0;
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);
}
NS_INLINE_DECL_REFCOUNTING(SharedMemory)
static void SystemProtect(char* aAddr, size_t aSize, int aRights);
static size_t SystemPageSize();
static size_t PageAlignedSize(size_t aSize);
protected:
SharedMemory();
// Implementations should call these methods on shmem usage changes,
// but *only if* the OS-specific calls are known to have succeeded.
// The methods are expected to be called in the pattern
//
// Created (Mapped Unmapped)* Destroy
//
// but this isn't checked.
void Created(size_t aNBytes);
void Mapped(size_t aNBytes);
void Unmapped();
void Destroyed();
// The size of the shmem region requested in Create(), if
// successful. SharedMemory instances that are opened from a
// foreign handle have an alloc size of 0, even though they have
// access to the alloc-size information.
size_t mAllocSize;
// The size of the region mapped in Map(), if successful. All
// SharedMemorys that are mapped have a non-zero mapped size.
size_t mMappedSize;
};
} // namespace ipc
} // namespace mozilla
#endif // ifndef mozilla_ipc_SharedMemory_h