#include <sys/mman.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <stdlib.h>
#include <unistd.h>
#define errExit(msg)    do { perror(msg); exit(EXIT_FAILURE); \
                                   } while (0)
int main() {
        int fd = open("file", O_CREAT|O_NOFOLLOW|O_RDWR, 0666);
        if (fd == -1) {
                errExit("open");
        }
        int size = 32;
        if (ftruncate(fd, size) == -1) {
                errExit("ftruncate");
        }
        void *addr = mmap(NULL, size, PROT_READ, MAP_SHARED, fd, 0);
        if (addr == MAP_FAILED) {
                errExit("mmap");
        }
        return 0;
}