#include <stdio.h>
#include <stdlib.h>
#include <unistd.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <sys/mman.h>

#define SIZE 17313792

void xperror(char *error_string)
{
	perror(error_string);
	exit(EXIT_FAILURE);
}

int main(int argc, char **argv)
{
	int shmid, *addr;
	char buffer[64];

	if ((shmid = shmget(21466751, SIZE, IPC_CREAT | IPC_EXCL | 0640)) < 0)
		xperror("shmget");
	addr = (int *) shmat(shmid, (char *) 0x50000000, 0);
	if (addr == (int *) -1)
		xperror("shmat 1");
	if (mprotect((char *) 0x51000000, 4096, PROT_READ) < 0)
		xperror("mprotect 1");
	if (mprotect((char *) 0x51081000, 4096, PROT_READ) < 0)
		xperror("mprotect 2");
	printf("First shmat & protects done: %08lx\n", (unsigned long) addr);
	sprintf(buffer, "cat /proc/%d/maps | grep /SYSV", getpid());
	system(buffer);
	if (shmdt(addr) < 0)
		xperror("shmdt 1");
	addr = (int *) shmat(shmid, (char *) 0x50000000, 0);
	if (addr == (int *) -1) {
		perror("shmat 2");
		shmctl(shmid, IPC_RMID, NULL);
		exit(EXIT_FAILURE);
	}
	printf("Second shmat done: %08lx\n", (unsigned long) addr);
	system(buffer);
	if (shmdt(addr) < 0)
		xperror("shmdt 2");
	shmctl(shmid, IPC_RMID, NULL);
	exit(EXIT_SUCCESS);
}