学步园

/*sharemem_write.c*/

#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <errno.h>
#include <stdio.h>
#include <sys/sem.h>
#define SHARE_SIZE 2048

union semun
{
   int val;                  /* value for SETVAL */
   struct semid_ds *buf;     /* buffer for IPC_STAT, IPC_SET */
   unsigned short *array;    /* array for GETALL, SETALL */
                                       /* Linux specific part: */
   struct seminfo *__buf;    /* buffer for IPC_INFO */
};

int sem_creat()
{
 int semid;
 semid=semget((key_t)8972,1,IPC_CREAT|0666);
 return semid;
}

void sem_setval(int semid)
{
     union semun semun_info;
     semun_info.val=1;
     semctl(semid,0,SETVAL,semun_info);  
}

void sem_p(int semid)
{
 struct sembuf  sem_buf;
 sem_buf.sem_num=0;
 sem_buf.sem_op=-1;
 sem_buf.sem_flg=SEM_UNDO;
 semop(semid,&sem_buf,1);
}

void sem_v(int semid)
{
 struct sembuf  sem_buf;
        sem_buf.sem_num=0;
        sem_buf.sem_op=1;
        sem_buf.sem_flg=SEM_UNDO;
        semop(semid,&sem_buf,1);
}

struct student
{
 char name[30];
 int age;
};

int main(int argc,char *argv[])
{
 int shmid;
 int semid;
 int i=0;
 struct student *stu_info;
 void *shm_addr=NULL;
 //semid=sem_creat();
 shmid=shmget((key_t)5566,SHARE_SIZE,IPC_CREAT|0666);
 shm_addr=shmat(shmid,NULL,0);
 stu_info=(struct student*)shm_addr;
 strcpy(stu_info->name,"cn0803 hzq");
 //sem_p(semid);
 stu_info->age++;
 printf("stu age %d\n",stu_info->age);
 sleep(1);
 stu_info->age++;
 printf("stu age %d\n",stu_info->age);
 sleep(1);
 //sem_v(semid);
 return 0;
}

/*sharememe_read.c*/

#include <sys/types.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <errno.h>
#include <stdio.h>
#define SHARE_SIZE 2048

struct student
{
        char name[30];
        int age;
};

int main(int argc,char *argv[])
{
 int shmid;
        struct student *stu_info;
        void *shm_addr=NULL;
        shmid=shmget((key_t)5566,SHARE_SIZE,IPC_CREAT|0666);
        shm_addr=shmat(shmid,NULL,0);
        stu_info=(struct student*)shm_addr;
 printf("student name %s\n",stu_info->name);
 shmdt(shm_addr);
 shmctl(shmid,IPC_RMID,NULL);
 return 0;
}