sem_fun.c

一组关于linux/unix下sem信号量的控制函数代码

#define SEM 0x9000L

static int sid;

int addsem(short sem_num)
{
	int abc;
	struct sembuf as[1] =
	{
		{0,1,SEM_UNDO|IPC_NOWAIT},
	};

	as[0].sem_num=sem_num;

	if ((abc=semop(sid,&as[0],1))<0)
	{
		sprintf(str,"¤￡ˉà2?￥[?H?1?O[%d]",sem_num);
		err_quit(str);
	}
	return(abc);
}

void decsem(short sem_num)
{
	int dec;
	struct sembuf as[1] =
	{
		{0,-1,IPC_NOWAIT},
	};

	as[0].sem_num=sem_num;

	if (semop(sid,&as[0],1)<0)
	{
		sprintf(str,"¤￡ˉà??′??H?1?O[%d]",sem_num);
		err_quit(str);
	}
}

void delsem()
{
	if ((sid=semget(SEM,MAX_SEM_NUM,PERMS))<0)
	{ 
	if (errno==ENOENT) return;
		else
		{
			sprintf(str,"¤￡ˉààò±o?H?1?O 0x%X",SEM);
			err_quit(str);
		}  
	}
	
	if (semctl(sid,0,GETVAL,0))
		err_quit("¤￡ˉà|P?é±ò°ê¨a-ó￥H¤W|?aA?1μ{|?");

	semctl(sid,1,IPC_RMID,0);
}



void creatsem(short sem_num)
{
	struct sembuf as[2] =
	{
		{0,0,0|IPC_CREAT},
		{0,1,0},
	};

	as[0].sem_num=sem_num;
	as[1].sem_num=sem_num;
	if ((sid=semget(SEM,MAX_SEM_NUM,PERMS|IPC_CREAT))<0)
	{
		sprintf(str,"¤￡ˉààò±o?H?1?O 0x%X",SEM);
		err_quit(str);  
  
	};
}



void testsem(short sem_num)
{
	int test;
	struct sembuf as[2] =
	{
		{0,0,0|IPC_CREAT},
		{0,1,0},
	};

	as[0].sem_num=sem_num;
	as[1].sem_num=sem_num;
	if ((sid=semget(SEM,MAX_SEM_NUM,PERMS|IPC_CREAT))<0)
	{
		sprintf(str,"¤￡ˉààò±o?H?1?O 0x%X",SEM);
		err_quit(str);  
  
	}
	if (semop(sid,&as[0],2)<0)
	{
		sprintf(str,"¤￡ˉàà?′ú?H?1?O[%d]",sem_num);
		err_quit(str);
	}
}

int valu_sem(ushort num)
{
	return (semctl(sid,num,GETVAL,0));
}