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

#define TESTSIZE (64*1024*1024)
#define FILENAME "my_tmp_file"

int main()
{
    int fd = open(FILENAME, O_RDWR | O_CREAT | O_TRUNC, 0600);
    if(fd>0) {
	unlink(FILENAME); /* The file is gone */
        if(lseek(fd, TESTSIZE, SEEK_SET)==TESTSIZE && write(fd, "x", 1)==1) {
	    int prot = PROT_READ|PROT_WRITE;
	    int flag = MAP_SHARED;
	    char *ptr = (char*) mmap(0, TESTSIZE, prot, flag, fd, 0);
	    if(ptr!=(char*)-1) {
		int idx, lcnt;
	        close(fd);
		/* Dirty the pages */
		for(lcnt=0; lcnt<3; lcnt++) {
		    for(idx=0; idx<TESTSIZE; idx+=1024) ptr[idx] = 'A';
		}

		/* leave */
		write(1, "Calling _exit()\n    ", 16);
		_exit(0);
	    }
	}
    }

    perror("Test program failed:");
    return -errno;
}