神马文学网linux 下信号量
来源：百度文库 编辑：神马文学网 时间：2024/04/27 19:31:00
#include
#include
#include
#include
#include
union semun
{
int val;
struct semid_ds *buf;
unsigned short int *array;
struct seminfo *_buf;
};
int
main(void)
{
key_t key;
int proj_id=1;
char * path_name="/home/informix/";//testSource/test";
key=ftok(path_name,proj_id);
if (key==-1)
{
perror("创建IPC关键字错误");
return -1;
}
int semid;
semid=semget(key,1,IPC_CREAT|0777);
if (semid==-1)
{
perror("创建信号量失败");
return -2;
}
union semun arg;
arg.val=1;
if (semctl(semid,0,SETVAL,arg)==-1)
{
perror("初始化信号量集失败");
return -3;
}
pid_t child;
int i;
struct sembuf wait_singal,notify;
wait_singal.sem_num=0;
wait_singal.sem_op=-1;
wait_singal.sem_flg=SEM_UNDO;
notify.sem_num=0;
notify.sem_op=1;
notify.sem_flg=SEM_UNDO;
pid_t pid_main=getpid();
for (i=0;i<5;i++)
{
child=fork();
}
/********************尝试进入临界区*******************/
while(semop(semid,&wait_singal,1)==-1)
{
if (errno!=EINTR) return -4;
printf("进程在进入临界区信号中断，将重置");
}
printf("进程: %d收到了信号灯上的信号\n",getpid());
/*******************离开临界区***********************/
while(semop(semid,¬ify,1)==-1)
{
if (errno!=EINTR) return -5;
printf("进程在退出临界区信号中断，将重置");
}
printf("进程: %d在信号灯上发送了信号\n\n",getpid());
if (!child) printf("父进程产生一个子进程\n",getpid());
while(wait(NULL)!=-1);
if (getpid()==pid_main)
{
printf("主进程的ID为：%d\n",pid_main);
if (semctl(semid,0,IPC_RMID,0)==-1)
{
perror("删除信号量错误");
return -6;
}
}
return 0;
}