server3.c

此源码是著名的教材BeginningLinux Programming中文名字叫Linux程序设计书中的源代码

#include <sys/types.h>
#include <linux/sem.h>

#define MAX_RESOURCE	5

int main(void)
{
	key_t		key;
	int		semid;
	struct sembuf	sbuf = {0, -1, IPC_NOWAIT};
	union semun	semopts;

	if ((key = ftok(".", 's')) == -1)
	{
		perror ("ftok error!\n");
		exit (1);
	}

	if ((semid = semget (key,1,IPC_CREAT|0666)) == -1)
	{
		perror ("semget error!\n");
		exit (1);
	}

	semopts.val = MAX_RESOURCE;
	if (semctl (semid,0,SETVAL, semopts) == -1)
	{
		perror ("semctl error!\n");
		exit (1);
	}

	while (1)
	{
		if(semop(semid, &sbuf, 1) == -1)
		{
			perror ("semop error!\n");
			exit (1);
		}
		sleep (3);
	}

	exit (0);
}