CreateFileMapping Function Explained

The CreateFileMapping function is used to create a file mapping object, which maps a file to one or more regions in the virtual address space of a process.

Function prototype:
HANDLE CreateFileMapping(
HANDLE hFile,
LPSECURITY_ATTRIBUTES lpAttributes,
DWORD flProtect,
DWORD dwMaximumSizeHigh,
DWORD dwMaximumSizeLow,
LPCTSTR lpName
);

Explanation of parameters:

1. hFile: The file handle associated with the file mapping. Obtain this handle by opening a file using the CreateFile function.
2. lpAttributes: a pointer to a SECURITY_ATTRIBUTES structure specifying the security attributes of the file mapping object. It can be NULL.
3. flProtect: Specifies the access protection attributes for a file mapping object. Common values include PAGE_READONLY, PAGE_READWRITE, and so on.
4. dwMaximumSizeHigh and dwMaximumSizeLow: specify the maximum size of the file mapping object. If it is 0, it means mapping the entire file.
5. The lpName parameter specifies the name of the file mapping object. It can be NULL.

Return value:

1. Success: Handle to the file mapping object.
2. Failure: NULL. You can use the GetLastError function to retrieve error information.

The file mapping object created using the CreateFileMapping function can be mapped to the virtual address space of a process using the MapViewOfFile function, allowing access to the file’s data using pointers.