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comparison: ipc/glue/SharedMemory.h
ipc/glue/SharedMemory.h
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| 1 /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- | |
| 2 * vim: sw=2 ts=8 et : | |
| 3 */ | |
| 4 /* This Source Code Form is subject to the terms of the Mozilla Public | |
| 5 * License, v. 2.0. If a copy of the MPL was not distributed with this | |
| 6 * file, You can obtain one at http://mozilla.org/MPL/2.0/. */ | |
| 7 | |
| 8 #ifndef mozilla_ipc_SharedMemory_h | |
| 9 #define mozilla_ipc_SharedMemory_h | |
| 10 | |
| 11 #include "nsDebug.h" | |
| 12 #include "nsISupportsImpl.h" // NS_INLINE_DECL_REFCOUNTING | |
| 13 #include "mozilla/Attributes.h" | |
| 14 | |
| 15 // | |
| 16 // This is a low-level wrapper around platform shared memory. Don't | |
| 17 // use it directly; use Shmem allocated through IPDL interfaces. | |
| 18 // | |
| 19 namespace { | |
| 20 enum Rights { | |
| 21 RightsNone = 0, | |
| 22 RightsRead = 1 << 0, | |
| 23 RightsWrite = 1 << 1 | |
| 24 }; | |
| 25 } | |
| 26 | |
| 27 namespace mozilla { | |
| 28 namespace ipc { | |
| 29 | |
| 30 class SharedMemory | |
| 31 { | |
| 32 public: | |
| 33 virtual ~SharedMemory() | |
| 34 { | |
| 35 MOZ_COUNT_DTOR(SharedMemory); | |
| 36 Unmapped(); | |
| 37 Destroyed(); | |
| 38 } | |
| 39 | |
| 40 enum SharedMemoryType { | |
| 41 TYPE_BASIC, | |
| 42 TYPE_SYSV, | |
| 43 TYPE_UNKNOWN | |
| 44 }; | |
| 45 | |
| 46 size_t Size() const { return mMappedSize; } | |
| 47 | |
| 48 virtual void* memory() const = 0; | |
| 49 | |
| 50 virtual bool Create(size_t size) = 0; | |
| 51 virtual bool Map(size_t nBytes) = 0; | |
| 52 | |
| 53 virtual SharedMemoryType Type() const = 0; | |
| 54 | |
| 55 void | |
| 56 Protect(char* aAddr, size_t aSize, int aRights) | |
| 57 { | |
| 58 char* memStart = reinterpret_cast<char*>(memory()); | |
| 59 if (!memStart) | |
| 60 NS_RUNTIMEABORT("SharedMemory region points at NULL!"); | |
| 61 char* memEnd = memStart + Size(); | |
| 62 | |
| 63 char* protStart = aAddr; | |
| 64 if (!protStart) | |
| 65 NS_RUNTIMEABORT("trying to Protect() a NULL region!"); | |
| 66 char* protEnd = protStart + aSize; | |
| 67 | |
| 68 if (!(memStart <= protStart | |
| 69 && protEnd <= memEnd)) | |
| 70 NS_RUNTIMEABORT("attempt to Protect() a region outside this SharedMemory"); | |
| 71 | |
| 72 // checks alignment etc. | |
| 73 SystemProtect(aAddr, aSize, aRights); | |
| 74 } | |
| 75 | |
| 76 NS_INLINE_DECL_REFCOUNTING(SharedMemory) | |
| 77 | |
| 78 static void SystemProtect(char* aAddr, size_t aSize, int aRights); | |
| 79 static size_t SystemPageSize(); | |
| 80 static size_t PageAlignedSize(size_t aSize); | |
| 81 | |
| 82 protected: | |
| 83 SharedMemory(); | |
| 84 | |
| 85 // Implementations should call these methods on shmem usage changes, | |
| 86 // but *only if* the OS-specific calls are known to have succeeded. | |
| 87 // The methods are expected to be called in the pattern | |
| 88 // | |
| 89 // Created (Mapped Unmapped)* Destroy | |
| 90 // | |
| 91 // but this isn't checked. | |
| 92 void Created(size_t aNBytes); | |
| 93 void Mapped(size_t aNBytes); | |
| 94 void Unmapped(); | |
| 95 void Destroyed(); | |
| 96 | |
| 97 // The size of the shmem region requested in Create(), if | |
| 98 // successful. SharedMemory instances that are opened from a | |
| 99 // foreign handle have an alloc size of 0, even though they have | |
| 100 // access to the alloc-size information. | |
| 101 size_t mAllocSize; | |
| 102 // The size of the region mapped in Map(), if successful. All | |
| 103 // SharedMemorys that are mapped have a non-zero mapped size. | |
| 104 size_t mMappedSize; | |
| 105 }; | |
| 106 | |
| 107 } // namespace ipc | |
| 108 } // namespace mozilla | |
| 109 | |
| 110 | |
| 111 #endif // ifndef mozilla_ipc_SharedMemory_h |
