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进程间通信(2) 内存映射FileMap
阅读量:81 次
发布时间:2019-02-25

本文共 3220 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:

在这里插入图片描述
在这里插入图片描述

【引用】

[1]: 代码地址

转载地址:http://dlm.baihongyu.com/

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