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进程间通信(2) 内存映射FileMap
阅读量:79 次
发布时间:2019-02-25

本文共 3224 字,大约阅读时间需要 10 分钟。

1.文件映射对象。

  • 文件映射对象是内核对象,它从系统的分页文件中获得一段内存。
  • 所有内核对象都共享同一个名字空间,所以名称不能重复。
  • 其他内核对象还有:事件,信号,互斥对象

2. 创建一个文件映射对象。

  • 为文件映射指明一个大小和名称。
  • windows api:CreateFileMapping

3. 对内核对象进行读写操作

windows api:MapViewOfFile

4. 示例

FULL_MAP_NAME 用来标记文件映射对象

server

// Prepare a message to be written to the view.      PWSTR pszMessage = (PWSTR)MESSAGE;    DWORD cbMessage = (wcslen(pszMessage) + 1) * sizeof(*pszMessage);    HANDLE hMapFile = NULL;    PVOID pView = NULL;    // Create the file mapping object.      hMapFile = CreateFileMapping(        INVALID_HANDLE_VALUE,   // Use paging file - shared memory          NULL,                   // Default security attributes          PAGE_READWRITE,         // Allow read and write access          0,                      // High-order DWORD of file mapping max size          MAP_SIZE,               // Low-order DWORD of file mapping max size          FULL_MAP_NAME           // Name of the file mapping object      );    if (hMapFile == NULL)    {
wprintf(L"CreateFileMapping failed w/err 0x%08lx\n", GetLastError()); goto Cleanup; } wprintf(L"The file mapping (%s) is created\n", FULL_MAP_NAME); // Map a view of the file mapping into the address space of the current // process. pView = MapViewOfFile( hMapFile, // Handle of the map object FILE_MAP_ALL_ACCESS, // Read and write access 0, // High-order DWORD of the file offset VIEW_OFFSET, // Low-order DWORD of the file offset VIEW_SIZE // The number of bytes to map to view ); if (pView == NULL) {
wprintf(L"MapViewOfFile failed w/err 0x%08lx\n", GetLastError()); goto Cleanup; } wprintf(L"The file view is mapped\n"); // Write the message to the view. memcpy_s(pView, VIEW_SIZE, pszMessage, cbMessage); wprintf(L"This message is written to the view:\n\"%s\"\n", pszMessage);

client

HANDLE hMapFile = NULL;    PVOID pView = NULL;    // Try to open the named file mapping identified by the map name.      hMapFile = OpenFileMapping(        FILE_MAP_READ,          // Read access          FALSE,                  // Do not inherit the name          FULL_MAP_NAME           // File mapping name       );    if (hMapFile == NULL)    {
wprintf(L"OpenFileMapping failed w/err 0x%08lx\n", GetLastError()); goto Cleanup; } wprintf(L"The file mapping (%s) is opened\n", FULL_MAP_NAME); // Map a view of the file mapping into the address space of the current // process. pView = MapViewOfFile( hMapFile, // Handle of the map object FILE_MAP_READ, // Read access 0, // High-order DWORD of the file offset VIEW_OFFSET, // Low-order DWORD of the file offset VIEW_SIZE // The number of bytes to map to view ); if (pView == NULL) {
wprintf(L"MapViewOfFile failed w/err 0x%08lx\n", GetLastError()); goto Cleanup; } wprintf(L"The file view is mapped\n"); // Read and display the content in view. wprintf(L"Read from the file mapping:\n\"%s\"\n", (PWSTR)pView);

结果:

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【引用】

[1]: 代码地址

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