/*the time server using shared memory */

#include<stdio.h>
#include<sys/shm.h>
#include<time.h>

#define TIME_MEM_KEY 99
#define SEG_SIZE ((size_t)100)
#define oops(m,x) {perror(m); exit(x);}

int seg_id;

void close_shm()
{
	shmctl( seg_id, IPC_RMID, NULL);

}

int main()
{
	int seg_id;
	char *mem_ptr, *ctime();
	long now;
	int n;
	    signal( SIGINT, (void*) close_shm);							//׽ctrl+c ź
	seg_id = shmget(TIME_MEM_KEY, SEG_SIZE, IPC_CREAT|0777);
	if ( seg_id == -1)
		oops("shmget", 1);

	mem_ptr = shmat( seg_id, NULL, 0);
	if( mem_ptr == (void *) -1)
		oops("shmat", 2);

	for (n = 0; n < 60; n++)
	{
		time( &now );
		strcpy(mem_ptr, ctime(&now));
		sleep(1);

	}

	shmctl( seg_id, IPC_RMID, NULL);

	return 0;

}