license.bot | f003cfe | 2008-08-24 09:55:55 +0900 | [diff] [blame^] | 1 | // Copyright (c) 2006-2008 The Chromium Authors. All rights reserved. |
| 2 | // Use of this source code is governed by a BSD-style license that can be |
| 3 | // found in the LICENSE file. |
initial.commit | 3f4a732 | 2008-07-27 06:49:38 +0900 | [diff] [blame] | 4 | |
brettw@google.com | e3c034a | 2008-08-08 03:31:40 +0900 | [diff] [blame] | 5 | #ifndef BASE_SHARED_MEMORY_H_ |
| 6 | #define BASE_SHARED_MEMORY_H_ |
initial.commit | 3f4a732 | 2008-07-27 06:49:38 +0900 | [diff] [blame] | 7 | |
brettw@google.com | e3c034a | 2008-08-08 03:31:40 +0900 | [diff] [blame] | 8 | #include "base/basictypes.h" |
initial.commit | 3f4a732 | 2008-07-27 06:49:38 +0900 | [diff] [blame] | 9 | #include "base/process_util.h" |
| 10 | |
| 11 | // SharedMemoryHandle is a platform specific type which represents |
| 12 | // the underlying OS handle to a shared memory segment. |
brettw@google.com | e3c034a | 2008-08-08 03:31:40 +0900 | [diff] [blame] | 13 | #if defined(OS_WIN) |
initial.commit | 3f4a732 | 2008-07-27 06:49:38 +0900 | [diff] [blame] | 14 | typedef HANDLE SharedMemoryHandle; |
| 15 | typedef HANDLE SharedMemoryLock; |
brettw@google.com | e3c034a | 2008-08-08 03:31:40 +0900 | [diff] [blame] | 16 | #elif defined(OS_POSIX) |
avi@google.com | 3a20898 | 2008-08-13 06:06:40 +0900 | [diff] [blame] | 17 | #include <semaphore.h> |
initial.commit | 3f4a732 | 2008-07-27 06:49:38 +0900 | [diff] [blame] | 18 | typedef int SharedMemoryHandle; |
avi@google.com | 3a20898 | 2008-08-13 06:06:40 +0900 | [diff] [blame] | 19 | typedef sem_t* SharedMemoryLock; |
initial.commit | 3f4a732 | 2008-07-27 06:49:38 +0900 | [diff] [blame] | 20 | #endif |
| 21 | |
| 22 | // Platform abstraction for shared memory. Provides a C++ wrapper |
| 23 | // around the OS primitive for a memory mapped file. |
| 24 | class SharedMemory { |
| 25 | public: |
| 26 | // Create a new SharedMemory object. |
| 27 | SharedMemory(); |
| 28 | |
| 29 | // Create a new SharedMemory object from an existing, open |
| 30 | // shared memory file. |
| 31 | SharedMemory(SharedMemoryHandle handle, bool read_only); |
| 32 | |
| 33 | // Create a new SharedMemory object from an existing, open |
| 34 | // shared memory file that was created by a remote process and not shared |
| 35 | // to the current process. |
| 36 | SharedMemory(SharedMemoryHandle handle, bool read_only, |
| 37 | ProcessHandle process); |
| 38 | |
| 39 | // Destructor. Will close any open files. |
| 40 | ~SharedMemory(); |
| 41 | |
| 42 | // Creates or opens a shared memory segment based on a name. |
| 43 | // If read_only is true, opens the memory as read-only. |
| 44 | // If open_existing is true, and the shared memory already exists, |
| 45 | // opens the existing shared memory and ignores the size parameter. |
| 46 | // Returns true on success, false on failure. |
| 47 | bool Create(const std::wstring &name, bool read_only, bool open_existing, |
| 48 | size_t size); |
| 49 | |
| 50 | // Opens a shared memory segment based on a name. |
| 51 | // If read_only is true, opens for read-only access. |
| 52 | // Returns true on success, false on failure. |
| 53 | bool Open(const std::wstring &name, bool read_only); |
| 54 | |
| 55 | // Maps the shared memory into the caller's address space. |
| 56 | // Returns true on success, false otherwise. The memory address |
| 57 | // is accessed via the memory() accessor. |
| 58 | bool Map(size_t bytes); |
| 59 | |
| 60 | // Unmaps the shared memory from the caller's address space. |
| 61 | // Returns true if successful; returns false on error or if the |
| 62 | // memory is not mapped. |
| 63 | bool Unmap(); |
| 64 | |
| 65 | // Get the size of the opened shared memory backing file. |
| 66 | // Note: This size is only available to the creator of the |
| 67 | // shared memory, and not to those that opened shared memory |
| 68 | // created externally. |
| 69 | // Returns 0 if not opened or unknown. |
| 70 | size_t max_size() const { return max_size_; } |
| 71 | |
| 72 | // Gets a pointer to the opened memory space if it has been |
| 73 | // Mapped via Map(). Returns NULL if it is not mapped. |
| 74 | void *memory() const { return memory_; } |
| 75 | |
| 76 | // Get access to the underlying OS handle for this segment. |
| 77 | // Use of this handle for anything other than an opaque |
| 78 | // identifier is not portable. |
| 79 | SharedMemoryHandle handle() const { return mapped_file_; } |
| 80 | |
| 81 | // Closes the open shared memory segment. |
| 82 | // It is safe to call Close repeatedly. |
| 83 | void Close(); |
| 84 | |
| 85 | // Share the shared memory to another process. Attempts |
| 86 | // to create a platform-specific new_handle which can be |
| 87 | // used in a remote process to access the shared memory |
| 88 | // file. new_handle is an ouput parameter to receive |
| 89 | // the handle for use in the remote process. |
| 90 | // Returns true on success, false otherwise. |
| 91 | bool ShareToProcess(ProcessHandle process, |
| 92 | SharedMemoryHandle *new_handle) { |
| 93 | return ShareToProcessCommon(process, new_handle, false); |
| 94 | } |
| 95 | |
| 96 | // Logically equivalent to: |
| 97 | // bool ok = ShareToProcess(process, new_handle); |
| 98 | // Close(); |
| 99 | // return ok; |
| 100 | bool GiveToProcess(ProcessHandle process, |
| 101 | SharedMemoryHandle *new_handle) { |
| 102 | return ShareToProcessCommon(process, new_handle, true); |
| 103 | } |
| 104 | |
| 105 | // Lock the shared memory. |
| 106 | // This is a cross-process lock which may be recursively |
| 107 | // locked by the same thread. |
| 108 | void Lock(); |
| 109 | |
| 110 | // Release the shared memory lock. |
| 111 | void Unlock(); |
| 112 | |
| 113 | private: |
avi@google.com | 9e0cc15 | 2008-08-14 04:59:07 +0900 | [diff] [blame] | 114 | #if defined(OS_POSIX) |
| 115 | bool CreateOrOpen(const std::wstring &name, int posix_flags); |
| 116 | #endif |
initial.commit | 3f4a732 | 2008-07-27 06:49:38 +0900 | [diff] [blame] | 117 | bool ShareToProcessCommon(ProcessHandle process, |
| 118 | SharedMemoryHandle *new_handle, bool close_self); |
| 119 | |
| 120 | std::wstring name_; |
| 121 | SharedMemoryHandle mapped_file_; |
| 122 | void* memory_; |
| 123 | bool read_only_; |
| 124 | size_t max_size_; |
| 125 | SharedMemoryLock lock_; |
| 126 | |
| 127 | DISALLOW_EVIL_CONSTRUCTORS(SharedMemory); |
| 128 | }; |
| 129 | |
| 130 | // A helper class that acquires the shared memory lock while |
| 131 | // the SharedMemoryAutoLock is in scope. |
| 132 | class SharedMemoryAutoLock { |
| 133 | public: |
| 134 | explicit SharedMemoryAutoLock(SharedMemory* shared_memory) |
| 135 | : shared_memory_(shared_memory) { |
| 136 | shared_memory_->Lock(); |
| 137 | } |
| 138 | |
| 139 | ~SharedMemoryAutoLock() { |
| 140 | shared_memory_->Unlock(); |
| 141 | } |
| 142 | |
| 143 | private: |
| 144 | SharedMemory* shared_memory_; |
| 145 | DISALLOW_EVIL_CONSTRUCTORS(SharedMemoryAutoLock); |
| 146 | }; |
| 147 | |
| 148 | |
brettw@google.com | e3c034a | 2008-08-08 03:31:40 +0900 | [diff] [blame] | 149 | #endif // BASE_SHARED_MEMORY_H_ |
license.bot | f003cfe | 2008-08-24 09:55:55 +0900 | [diff] [blame^] | 150 | |