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."); 
}