Windows IPC 进程间通信之共享内存

1. 必须先创建共享内存，才能够打开
2. 关闭共享内存后，就无法打开
3. 使用Global则必须是管理员权限才能创建或打开

相当于要读写一个文件，必须先创建文件才能够打开，删掉文件后就无法打开。权限不够的话就无法读写

1. // share_memory.cpp : 定义控制台应用程序的入口点。
   
2. //
   
3. 
   
4. #include "stdafx.h"
   
5. #include <Windows.h>
   
6. #include <stdio.h>
   
7. #include <conio.h>
   
8. #include <tchar.h>
   
9. 
   
10. #define BUF_SIZE 256
    
11. TCHAR szName[]=TEXT("Global\\MyFileMappingObject");
    
12. TCHAR szMsg[]=TEXT("Message from first process.");
    
13. 
    
14. int p1();
    
15. int p2();
    
16. 
    
17. int _tmain(int argc, _TCHAR* argv[])
    
18. {
    
19.     if ( argc == 1 )
    
20.     {
    
21.         p1();
    
22.     }
    
23.     else
    
24.     {
    
25.         p2();
    
26.     }
    
27.     return 0;
    
28. }
    
29. 
    
30. 
    
31. int p1()
    
32. {
    
33.    HANDLE hMapFile;
    
34.    LPCTSTR pBuf;
    
35. 
    
36.    hMapFile = CreateFileMapping(
    
37.                  INVALID_HANDLE_VALUE, // use paging file
    
38.                  NULL, // default security
    
39.                  PAGE_READWRITE, // read/write access
    
40.                  0, // maximum object size (high-order DWORD)
    
41.                  BUF_SIZE, // maximum object size (low-order DWORD)
    
42.                  szName); // name of mapping object
    
43. 
    
44.    if (hMapFile == NULL)
    
45.    {
    
46.       _tprintf(TEXT("Could not create file mapping object (%d).\n"),
    
47.              GetLastError());
    
48.       return 1;
    
49.    }
    
50.    pBuf = (LPTSTR) MapViewOfFile(hMapFile, // handle to map object
    
51.                         FILE_MAP_ALL_ACCESS, // read/write permission
    
52.                         0,
    
53.                         0,
    
54.                         BUF_SIZE);
    
55. 
    
56.    if (pBuf == NULL)
    
57.    {
    
58.       _tprintf(TEXT("Could not map view of file (%d).\n"),
    
59.              GetLastError());
    
60. 
    
61.        CloseHandle(hMapFile);
    
62. 
    
63.       return 1;
    
64.    }
    
65. 
    
66. 
    
67.    CopyMemory((PVOID)pBuf, szMsg, (_tcslen(szMsg) * sizeof(TCHAR)));
    
68.     _getch();
    
69. 
    
70.    UnmapViewOfFile(pBuf);
    
71. 
    
72.    CloseHandle(hMapFile);
    
73. 
    
74.    return 0;
    
75. }
    
76. 
    
77. int p2()
    
78. {
    
79.    HANDLE hMapFile;
    
80.    LPCTSTR pBuf;
    
81. 
    
82.    hMapFile = OpenFileMapping(
    
83.                    FILE_MAP_ALL_ACCESS, // read/write access
    
84.                    FALSE, // do not inherit the name
    
85.                    szName); // name of mapping object
    
86. 
    
87.    if (hMapFile == NULL)
    
88.    {
    
89.       _tprintf(TEXT("Could not open file mapping object (%d).\n"),
    
90.              GetLastError());
    
91.       return 1;
    
92.    }
    
93. 
    
94.    pBuf = (LPTSTR) MapViewOfFile(hMapFile, // handle to map object
    
95.                FILE_MAP_ALL_ACCESS, // read/write permission
    
96.                0,
    
97.                0,
    
98.                BUF_SIZE);
    
99. 
    
100.    if (pBuf == NULL)
     
101.    {
     
102.       _tprintf(TEXT("Could not map view of file (%d).\n"),
     
103.              GetLastError());
     
104. 
     
105.       CloseHandle(hMapFile);
     
106. 
     
107.       return 1;
     
108.    }
     
109. 
     
110.    MessageBox(NULL, pBuf, TEXT("Process2"), MB_OK);
     
111. 
     
112.    UnmapViewOfFile(pBuf);
     
113. 
     
114.    CloseHandle(hMapFile);
     
115. 
     
116.    return 0;
     
117. }