22.内存映射文件

Notes #滴水基础_Win32

什么是内存映射文件？

截图 202607312015

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DWORD MappingFile(LPSTR lpcFile){
    HANDLE hFile;
    HANDLE hMapFile;
    LPVOID lpAddr;
    //获取文件句柄
    hFile = CreateFileA(
        lpcFile,
        GENERIC_READ | GENERIC_WRITE,
        0,
        NULL,
        OPEN_EXISTING,
        FILE_ATTRIBUTE_NORMAL,
        NULL
    );
    if (hFile == INVALID_HANDLE_VALUE) {
        printf("CreateFile 失败:%lx \n",GetLastError());
        return 0;
    }
    //创建FileMapping对象
    hMapFile = CreateFileMappingA(
        hFile,
        NULL,
        PAGE_READWRITE,
        0,
        0,
        NULL);
    if (hMapFile == NULL) {
        printf("CreateFileMapping 失败:%lx \n",GetLastError());
        CloseHandle(hFile);
        return 0;
    }
    //映射到虚拟内存
    lpAddr = MapViewOfFile(
        hMapFile,
        FILE_MAP_READ | FILE_MAP_WRITE,
        0,
        0,
        0);
    if (lpAddr == NULL) {
        printf("MapViewOfFile 失败:%lx \n",GetLastError());
        CloseHandle(hMapFile);
        CloseHandle(hFile);
        return 0;
    }
    //读取文件
    DWORD dwTest1 = *(PDWORD) lpAddr;
    DWORD dwTest2 = *((PDWORD)lpAddr+0x188fc);
    printf("%lx %lx\n",dwTest1,dwTest2);

    //写文件
    *(PDWORD)lpAddr = 0x12345678;
    printf("写入: %lx\n",*(PDWORD)lpAddr);
    //强制更新缓存
    FlushViewOfFile(lpAddr,4);

    UnmapViewOfFile(lpAddr);
    CloseHandle(hMapFile);
    CloseHandle(hFile);

    return 0;
}
  • 操作方便，对大文件的读取友好

内存映射文件之共享

202607312100 1

内存映射文件之写拷贝

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由 GuQing 撰写，采用 CC BY-NC 4.0 许可协议。