mmap.c

#include <sys/mman.h>

#include <err.h>
#include <fcntl.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>

#define MAP_NAM		"/var/tmp/test_map_0"
#define MAP_SZ		(1024*1024*1024)

static void
mmap_sigint()
{
	return 0;
}

static void
mmap_pause()
{
	warnx("paused - press Ctrl+C");
	(void)pause();
}

int
main(void)
{
	int fd;
	unsigned char *arr, *c, acc = 0;

	if (signal(SIGINT, mmap_sigint) == SIG_ERR)
		err(1, "signal");

	warnx("open");
	fd = open(MAP_NAM, O_RDWR|O_CREAT|O_TRUNC, 0644);
	if (fd == -1)
		err(1, "open");

	warnx("truncate");
	if (ftruncate(fd, MAP_SZ) == -1)
		err(1, "ftruncate");

	warnx("map");
	arr = mmap(NULL, MAP_SZ, PROT_READ|PROT_WRITE, MAP_SHARED, fd, 0);
	if (arr == NULL)
		err(1, "mmap");
	mmap_pause();

	warnx("access\n");
	for (c = arr; c < arr + MAP_SZ; ++c)
		acc += *c;
	warnx("finished: %c\n", acc);
	mmap_pause();

	warnx("munmap\n");
	if (munmap(arr, MAP_SZ) == -1)
		err(1, "munmap");
	mmap_pause();

	return EXIT_SUCCESS;
}