Creating Named Shared Memory

The first process calls the CreateFileMapping function to create a file-mapping object and give it the name MyFileMappingObject. By using the PAGE_READWRITE flag, the processes will have read/write permission to the memory through any file views that are created.

HANDLE hMapFile;

hMapFile = CreateFileMapping(hFile, // Current file handle.

NULL, // Default security.

PAGE_READWRITE, // Read/write permission.

0, // Max. object size.

0, // Size of hFile.

"MyFileMappingObject"); // Name of mapping object.

if (hMapFile == NULL) {

ErrorHandler("Could not create file-mapping object.");

}

The process then uses the file-mapping object handle returned by CreateFileMapping in the call to MapViewOfFile to create a view of the file in the process's address space. The MapViewOfFile function returns a pointer to the file view.

LPVOID lpMapAddress;

lpMapAddress = MapViewOfFile(hMapFile, // Handle to mapping object.

FILE_MAP_ALL_ACCESS, // Read/write permission

0, // Max. object size.

0, // Size of hFile.

0); // Map entire file.

if (lpMapAddress == NULL) {

ErrorHandler("Could not map view of file.");

}

The second process calls the OpenFileMapping function with the name MyFileMappingObject to use the same file-mapping object as the first process. Like the first process, the second process uses the MapViewOfFile function to obtain a pointer to the file view.

HANDLE hMapFile;

LPVOID lpMapAddress;

hMapFile = OpenFileMapping(FILE_MAP_ALL_ACCESS, // Read/write permission.

FALSE, // Do not inherit the name

"MyFileMappingObject"); // of the mapping object.

if (hMapFile == NULL) {

ErrorHandler("Could not open file-mapping object.");

}

lpMapAddress = MapViewOfFile(hMapFile, // Handle to mapping object.

FILE_MAP_ALL_ACCESS, // Read/write permission.

0, // Max. object size.

0, // Size of hFile.

0); // Map entire file.

if (lpMapAddress == NULL) {

ErrorHandler("Could not map view of file.");

}

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