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| #include<stdio.h>
#include<stdlib.h>
#include<sys/types.h>
#include<sys/ipc.h>
#include<sys/sem.h>
union semun{
int val;
struct semid_ds *buf;
unsigned short *array;
struct seminfo *__buf;
}arg;
int semid;
philosopher(int i)
{
int j;
struct sembuf sbuf[2];
sbuf[0].sem_num=i;
sbuf[0].sem_flg=SEM_UNDO;
sbuf[1].sem_num=(i+1)%5;
sbuf[1].sem_flg=SEM_UNDO;
for(j=0;j<5;j++)
{
printf("philosopher %d is thinking\n",i);
sleep(2);
printf("philosopher %d is hungry\n",i);
sbuf[0].sem_op=-1;
sbuf[1].sem_op=-1;
semop(semid,sbuf,2);
printf("philosopher %d is eating\n",i);
sleep(2);
sbuf[0].sem_op=1;
sbuf[1].sem_op=1;
semop(semid,sbuf,2);
}
exit(i);
}
int main(){
int semid,key,pid,status,i;
key=ftok("fname",1);
semid=semget(key,5,IPC_CREAT|0666);
arg.val=1;
for(i=0;i<5;i++)
semctl(semid,i,SETVAL,arg);
for(i=0;i<5;i++)
{
pid=fork();
if(pid==0)
philosopher(i);
}
pid=wait(&status);
}
|