#include <stdlib.h>
#include <stdio.h>

#include <errno.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/mman.h>

int main (int ac, char **av) {
	int segs, size, proc, rmpr;
	unsigned long long iter;
	pid_t pid;
	struct stat buf;

	if (ac < 6) {
		printf ("usage: shmtst segs size proc iter rm%%\n");
		exit (1);
	}
	segs = atoi (av[1]);
	size = atoi (av[2]);
	proc = atoi (av[3]);
	iter = atoi (av[4]);
	rmpr = atoi (av[5]);

	iter = 1 << iter;
	printf ("using %d segs of size %d (%llu iterations)\n", 
		segs, size, iter);
	while (-- proc) {
		if ((pid = fork()) > 0) {
			printf ("started process %d\n", (int) pid);
		} else {
			break;
		}
	}
	srandom (getpid());
	while (iter--) {
		int seg, key;
		char name[20];
		char *ptr, *p;

		key = random() % segs;
		sprintf (name, "my%d", key);
		if ((seg = shm_open (name, O_CREAT| O_RDWR , 0666)) == -1) {
			perror("shm_open");
			exit (1);
		}
	        if (ftruncate (seg, size) == -1) {
			perror ("ftruncate");
			exit (2);
		}
	        if ((ptr = mmap (0, size, PROT_READ|PROT_WRITE,MAP_SHARED,
				 seg, 0)) == MAP_FAILED) {	
			perror ("mmap");
			exit (3);
		}
		for (p = ptr; p < ptr + size; p += 4097)
			*p = (char) p;
		for (p = ptr; p < ptr + size; p += 4097)
			if (*p != (char)p)
				printf ("*p(%i) != p(%i)\n", (int)*p, (int)p & 0xff);

	    	if (munmap (ptr, size) == -1)
			perror ("munmap");

	    	if (close(seg) == -1)
			perror ("close");

		if (random () % 100 < rmpr &&
		    shm_unlink (name) == -1) 
			perror("shm_unlink");
	}
}