Win CE：创建命名共享内存

Question

我尝试在win CE 6.0上创建命名共享内存，但是可能该进程不保存数据。 我写了两个过程。第一次将文本写入共享内存和第二次读取。第二个显示空消息窗口。

第一进程：

#include "stdafx.h" 
#include <stdlib.h> 

#define BUFFSIZE 256 
TCHAR szName[]=TEXT("MyFileMappingObject"); 
TCHAR szText[]=TEXT("Process write"); 

int _tmain(int argc, TCHAR *argv[], TCHAR *envp[]) 
{ 
HANDLE hMutex; 
HANDLE hMapFile; 
LPCTSTR pBuff; 
BOOL fFirstApp = TRUE; 
int rc; 

// Create mutex used to share memory-mapped structure. 
hMutex = CreateMutex (NULL, TRUE, TEXT ("MyFileMOWRT")); 
rc = GetLastError(); 
if (rc == ERROR_ALREADY_EXISTS) 
    fFirstApp = FALSE; 
else if (rc) 
{ 
    _tprintf(TEXT("rc1 (%d).\n"), GetLastError()); 
    return 0; 
} 

// Wait here for ownership to ensure that the initialization is done. 
// This is necessary since CreateMutex doesn’t wait. 
rc = WaitForSingleObject(hMutex, 2000); 
if (rc != WAIT_OBJECT_0) 
{ 
    _tprintf(TEXT("rc2 wait (%d).\n"), GetLastError()); 
    return 0; 
} 

// Create a file-mapping object. 
hMapFile = CreateFileMapping(INVALID_HANDLE_VALUE, NULL, PAGE_READWRITE, 0, 
          BUFFSIZE, szName); 
if (hMapFile == NULL) 
{ 
    _tprintf(TEXT("Could not create file mapping object (%d).\n"), GetLastError()); 
    return 1; 
} 
else 
    printf("File mapping object was created\n"); 

// Map into memory the file-mapping object. 
pBuff = (LPTSTR)MapViewOfFile(hMapFile, FILE_MAP_WRITE, 0, 0, BUFFSIZE); 
if (pBuff == NULL) 
{ 
    _tprintf(TEXT("Could not map view of file (%d).\n"), GetLastError()); 
    CloseHandle(hMapFile); 

    return 1; 
} 
else 
    printf("Map view of file\n"); 

CopyMemory((PVOID)pBuff, szText, (_tcslen(szText) * sizeof(TCHAR))); 

UnmapViewOfFile(pBuff); 

// Release the mutex. We need to release the mutex twice 
// if we owned it when we entered the wait above. ReleaseMutex(hMutex); 
ReleaseMutex(hMutex); 
if (fFirstApp) 
    ReleaseMutex(hMutex); 

CloseHandle(hMapFile); 
CloseHandle(hMutex); 

return 0; 
} 

第二个过程：它运行过程

#include "stdafx.h" 
#include <stdlib.h> 

#define BUFFSIZE 256 
TCHAR szName[]=TEXT("MyFileMappingObject"); 

int _tmain(int argc, TCHAR *argv[], TCHAR *envp[]) 
{ 
    HANDLE hMutex; 
HANDLE hMapFile; 
LPCTSTR pBuf; 
BOOL fFirstApp = TRUE; 
int rc; 

// Create mutex used to share memory-mapped structure. 
hMutex = CreateMutex (NULL, TRUE, TEXT ("MyFileMOWRT")); 
rc = GetLastError(); 
if (rc == ERROR_ALREADY_EXISTS) 
    fFirstApp = FALSE; 
else if (rc) 
{ 
    _tprintf(TEXT("rc1 (%d).\n"), GetLastError()); 
    return 0; 
} 

// Wait here for ownership to ensure that the initialization is done. 
// This is necessary since CreateMutex doesn’t wait. 
rc = WaitForSingleObject(hMutex, 2000); 
if (rc != WAIT_OBJECT_0) 
{ 
    _tprintf(TEXT("rc2 wait (%d).\n"), GetLastError()); 
    return 0; 
} 

// Create a file-mapping object. 
hMapFile = CreateFileMapping(INVALID_HANDLE_VALUE, NULL, PAGE_READWRITE, 0, 
          BUFFSIZE, szName); 
if (hMapFile == NULL) 
{ 
    _tprintf(TEXT("Could not create file mapping object (%d).\n"), GetLastError()); 
    return 1; 
} 
else 
    printf("File mapping object was created\n"); 

pBuf = (LPTSTR) MapViewOfFile(hMapFile, FILE_MAP_READ, 0, 0, 0);  
if (pBuf) 
{ 
    MessageBox(NULL, pBuf, TEXT("Process2"), MB_OK); 
} 
else 
{ 
    _tprintf(TEXT("Could not map view of file (%d).\n"), GetLastError()); 
    CloseHandle(hMapFile); 

    return 1; 
} 

UnmapViewOfFile(pBuf); 

// Release the mutex. We need to release the mutex twice 
// if we owned it when we entered the wait above. ReleaseMutex(hMutex); 
ReleaseMutex(hMutex); 
if (fFirstApp) 
    ReleaseMutex(hMutex); 

CloseHandle(hMapFile); 
CloseHandle(hMutex); 

return 0; 
} 

计划：

#include "stdafx.h" 
#include <stdlib.h> 

int _tmain(int argc, TCHAR *argv[], TCHAR *envp[]) 
{ 
    CreateProcess(TEXT("\\Windows\\Mutex_proces.exe"), NULL, 0,0,0,0,0,0,0,0); 
    CreateProcess(TEXT("\\Windows\\Mutex_proces_rd.exe"), NULL, 0,0,0,0,0,0,0,0); 

    return 0; 
} 

Answer 1

后你的指针从MapViewOfFile共享内存，你的代码中都进程应该设置同步模式，以便从/向这个内存读取/写入：

过程1 - P1

1. 创建名为文件映射
2. 得到指针存储器
3. 写入存储器
4. 创建命名互斥，
5. 信号化到P2（使用互斥），它写了内存，P2可以读取它。 。
6. P1应该等待，直到P2读取共享存储器，它可以在简单地互斥等待从点4

过程2 - P2

1. 创建名为互斥，但然后或者如果它不存在返回错误，或等到P1创建此互斥锁。
2. 创建名为文件映射和获取指向其内存
3. 句柄互斥体（从1）是获得性，P2现在等待P1信号（使用WaitForSingleObject的）
4. 当信号到达，那么你可以阅读记忆，阅读后释放互斥体，使P1可以从6