file_mapping.c File Reference

#include <memory.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <fcntl.h>
#include <unistd.h>
#include <sys/mman.h>
#include <sys/stat.h>

Include dependency graph for file_mapping.c:

Functions
void	map_file_window (const char *filename, size_t offset, size_t length, void **addr, void **ptr, int read_write, int unique_name, int create_new)
	Map data segment from file.
void	unmap_file_window (void *addr, size_t length)
	Cancel file mapping.

Function Documentation

map_file_window()

void map_file_window	(	const char *	filename,
		size_t	offset,
		size_t	length,
		void **	addr,
		void **	ptr,
		int	read_write,
		int	unique_name,
		int	create_new )

Map data segment from file.

Authors

J Benda

Date

2020 - 2025

Assigns a virtual memory range to a contiguous data segment within a disk file, which can be used as any other memory buffer. The file need not exist; if create_new is set to 1, it will be created first, sufficiently large to hold the requested memory range. The file name can be left partially unspecified (by setting unique_name to 1) to allow the operating system to generate a unique file path with the prefix given by filename. Such automatically created files will be deleted once the mapping is canceled (or the program ends).

Parameters

[in]	filename	Path to the file to map or a prefix for automatically generated name.
[in]	offset	Byte position in file to begin the mapping.
[in]	length	Byte length of the mapped window (buffer).
[out]	addr	Internal address that needs to be passed to unmap_file_window to cancel the mapping.
[out]	ptr	Pointer to memory where the mapped data begin.
[in]	read_write	If set to 1, allow write access to the mapped memory.
[in]	unique_name	If set to 1, interpret filename only as a prefix, and supplement it with a unique ending.
[in]	create_new	If set to 1, create a new file instead of mapping an existing one.

unmap_file_window()

void unmap_file_window	(	void *	addr,
		size_t	length )

Cancel file mapping.

Authors

J Benda

Date

2020 - 2021

Release memory mapping, allowing e.g. final deletion of the file.

Parameters

[in]	addr	Internal address obtained from map_file_window.
[in]	length	Length of the mapped data segment.