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138 lines
4.2 KiB
C++
138 lines
4.2 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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* vim: sw=2 ts=8 et :
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*/
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/* ***** BEGIN LICENSE BLOCK *****
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* Version: MPL 1.1/GPL 2.0/LGPL 2.1
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*
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* The contents of this file are subject to the Mozilla Public License Version
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* 1.1 (the "License"); you may not use this file except in compliance with
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* the License. You may obtain a copy of the License at
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* http://www.mozilla.org/MPL/
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*
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* Software distributed under the License is distributed on an "AS IS" basis,
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* WITHOUT WARRANTY OF ANY KIND, either express or implied. See the License
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* for the specific language governing rights and limitations under the
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* License.
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*
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* The Original Code is Mozilla IPC.
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*
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* The Initial Developer of the Original Code is
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* The Mozilla Foundation
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* Portions created by the Initial Developer are Copyright (C) 2009-2010
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* the Initial Developer. All Rights Reserved.
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*
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* Contributor(s):
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*
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* Alternatively, the contents of this file may be used under the terms of
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* either the GNU General Public License Version 2 or later (the "GPL"), or
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* the GNU Lesser General Public License Version 2.1 or later (the "LGPL"),
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* in which case the provisions of the GPL or the LGPL are applicable instead
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* of those above. If you wish to allow use of your version of this file only
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* under the terms of either the GPL or the LGPL, and not to allow others to
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* use your version of this file under the terms of the MPL, indicate your
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* decision by deleting the provisions above and replace them with the notice
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* and other provisions required by the GPL or the LGPL. If you do not delete
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* the provisions above, a recipient may use your version of this file under
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* the terms of any one of the MPL, the GPL or the LGPL.
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*
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* ***** END LICENSE BLOCK ***** */
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#ifndef mozilla_ipc_SharedMemory_h
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#define mozilla_ipc_SharedMemory_h
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#include "nsDebug.h"
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#include "nsISupportsImpl.h" // NS_INLINE_DECL_REFCOUNTING
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//
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// This is a low-level wrapper around platform shared memory. Don't
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// use it directly; use Shmem allocated through IPDL interfaces.
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//
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namespace {
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enum Rights {
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RightsNone = 0,
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RightsRead = 1 << 0,
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RightsWrite = 1 << 1
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};
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}
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namespace mozilla {
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namespace ipc {
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class SharedMemory
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{
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public:
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enum SharedMemoryType {
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TYPE_BASIC,
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TYPE_SYSV,
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TYPE_UNKNOWN
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};
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virtual ~SharedMemory() { Unmapped(); Destroyed(); }
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size_t Size() const { return mMappedSize; }
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virtual void* memory() const = 0;
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virtual bool Create(size_t size) = 0;
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virtual bool Map(size_t nBytes) = 0;
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virtual SharedMemoryType Type() const = 0;
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void
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Protect(char* aAddr, size_t aSize, int aRights)
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{
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char* memStart = reinterpret_cast<char*>(memory());
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if (!memStart)
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NS_RUNTIMEABORT("SharedMemory region points at NULL!");
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char* memEnd = memStart + Size();
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char* protStart = aAddr;
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if (!protStart)
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NS_RUNTIMEABORT("trying to Protect() a NULL region!");
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char* protEnd = protStart + aSize;
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if (!(memStart <= protStart
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&& protEnd <= memEnd))
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NS_RUNTIMEABORT("attempt to Protect() a region outside this SharedMemory");
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// checks alignment etc.
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SystemProtect(aAddr, aSize, aRights);
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}
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NS_INLINE_DECL_REFCOUNTING(SharedMemory)
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static void SystemProtect(char* aAddr, size_t aSize, int aRights);
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static size_t SystemPageSize();
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static size_t PageAlignedSize(size_t aSize);
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protected:
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SharedMemory();
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// Implementations should call these methods on shmem usage changes,
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// but *only if* the OS-specific calls are known to have succeeded.
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// The methods are expected to be called in the pattern
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//
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// Created (Mapped Unmapped)* Destroy
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//
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// but this isn't checked.
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void Created(size_t aNBytes);
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void Mapped(size_t aNBytes);
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void Unmapped();
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void Destroyed();
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// The size of the shmem region requested in Create(), if
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// successful. SharedMemory instances that are opened from a
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// foreign handle have an alloc size of 0, even though they have
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// access to the alloc-size information.
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size_t mAllocSize;
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// The size of the region mapped in Map(), if successful. All
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// SharedMemorys that are mapped have a non-zero mapped size.
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size_t mMappedSize;
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};
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} // namespace ipc
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} // namespace mozilla
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#endif // ifndef mozilla_ipc_SharedMemory_h
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