Windowsfilkartlegging

Windowsfilkartlegging, often translated as Windows file mapping, refers to a technique used in Windows operating systems to associate a file on disk with a region of virtual memory. This process allows a program to access and manipulate the contents of a file as if it were a memory array, bypassing traditional file I/O operations like read() and write().

The primary mechanism for file mapping is the CreateFileMapping function, which creates a named or unnamed file mapping object. This object represents the entire file or a portion of it in memory. Subsequently, the MapViewOfFile function is used to map a view of this file mapping object into the process's address space. The program can then access the mapped memory region directly using pointers.

File mapping offers several advantages. It can significantly improve performance for large files by allowing the operating system to manage caching and memory allocation efficiently. It also simplifies programming by enabling direct memory access, and it facilitates inter-process communication by allowing multiple processes to map the same file into their respective address spaces, thus sharing data.

The mapped memory can be read-only, write-copy, or read/write, depending on the protection flags specified during the mapping. When changes are made to the mapped memory, the operating system is responsible for writing these modifications back to the underlying file on disk, either lazily or immediately. Unmapping the memory view is done using UnmapViewOfFile, and the file mapping object itself is closed with CloseHandle. This technique is fundamental for various system-level operations and application functionalities within the Windows environment.