生产者和消费者（PV操作、共享内存）

生产者一直在往共享内存中写数据

#include<sys/sem.h>#include<sys/shm.h>#include<stdio.h>#include<stdlib.h>#include<errno.h>#include"shm.h"int main(){    int ret;    int shmid;    int semid;    int running;    void *share_memory;    struct shm *shm_buf;    //创建信号量    semid = semget(ftok(".",'a'),1,IPC_CREAT);    if(semid < 0)    {        perror("semid:");    exit(1);    }    //初始化信号量    sem_init(semid,1);    //创建共享内存    shmid = shmget(ftok(".",'b'),sizeof(struct shm),IPC_CREAT);    if(shmid < 0)    {        perror("shmget:");    exit(1);    }    //映射共享内存    share_memory = shmat(shmid,NULL,0);    if(share_memory == (void *)-1)    {        perror("shmat:");    sem_del(semid);    exit(1);    }    printf("share_memory = %p\n",share_memory);    //指向共享内存    shm_buf = (struct shm*)share_memory;    while(running)    {        p_sem(semid);//    printf("please input something to memory:\n");    scanf("%s",&shm_buf->buf);    shm_buf->flag = getpid();    if(strcmp(shm_buf->buf,"end") == 0)    {        running = 0;    }    v_sem(semid);//做加法    }    sem_del(semid);    if(shmdt(share_memory) == -1)    {        perror("shmdt:");    exit(1);    }    return 0;}

消费者一直从内存中读取数据，一次读完之后就把内存清空

#include<sys/sem.h>#include<sys/shm.h>#include<sys/fcntl.h>#include<stdio.h>#include<stdlib.h>#include<errno.h>#include<sys/types.h>#include"shm.h"int main(){    struct shm *shm_buf;    void *share_memory;    int semid;    int shmid;    int running = 1;//创建信号量，生产者和消费者的key值要对应相等    semid = semget(ftok(".",'a'),1,0666);    if(semid == -1)    {        perror("producer do not exit:");    exit(1);    }     shmid = shmget(ftok(".",'b'),sizeof(struct shm),IPC_CREAT);    if(shmid == -1)    {        perror("shmget error:");    exit(1);    }    share_memory = shmat(shmid,NULL,0);    if(share_memory == (void *)-1)    {        perror("shmat failed:");    exit(1);    }    printf("share_memory = %p\n",share_memory);    shm_buf = (struct shm*)share_memory;    while(running)    {        p_sem(semid);      printf("process write memory %d: %s\n",shm_buf->flag,shm_buf->buf);    if(strcmp(shm_buf->buf,"end") == 0)    {        //running = 0;        exit(1);    }    shm_buf->flag = 0;    memset(shm_buf->buf,0,BUF_SIZE);    v_sem(semid);    }    if(shmdt(share_memory) == -1)    {        perror("share_memory:");    exit(1);    }    if(shmctl(shmid,IPC_RMID,NULL) == -1)    {        perror("shmctl:");    exit(1);    }    exit(0);}

头文件：

#include<sys/sem.h>#include<sys/shm.h>#include<sys/fcntl.h>#include<stdio.h>#include<stdlib.h>#include<errno.h>#include<sys/types.h>#include"shm.h"int main(){    struct shm *shm_buf;    void *share_memory;    int semid;    int shmid;    int running = 1;    semid = semget(ftok(".",'a'),1,0666);    if(semid == -1)    {        perror("producer do not exit:");    exit(1);    }     shmid = shmget(ftok(".",'b'),sizeof(struct shm),IPC_CREAT);    if(shmid == -1)    {        perror("shmget error:");    exit(1);    }    share_memory = shmat(shmid,NULL,0);    if(share_memory == (void *)-1)    {        perror("shmat failed:");    exit(1);    }    printf("share_memory = %p\n",share_memory);    shm_buf = (struct shm*)share_memory;    while(running)    {        p_sem(semid);      printf("process write memory %d: %s\n",shm_buf->flag,shm_buf->buf);    if(strcmp(shm_buf->buf,"end") == 0)    {        //running = 0;        exit(1);    }    shm_buf->flag = 0;    memset(shm_buf->buf,0,BUF_SIZE);    v_sem(semid);    }    if(shmdt(share_memory) == -1)    {        perror("share_memory:");    exit(1);    }    if(shmctl(shmid,IPC_RMID,NULL) == -1)    {        perror("shmctl:");    exit(1);    }    exit(0);}

重写的pv操作、删除信号量和初始化信号量的函数

#include<sys/ipc.h>#include<sys/shm.h>#include<stdlib.h>#include<sys/sem.h>#include"shm.h"int sem_init(int semid,int pid){    union semnum sem_num;    sem_num.pid = pid;    if(semctl(semid,0,SETVAL,sem_num) == -1)    {        perror("fail sem_init");    exit(1);    }    return 0;}int sem_del(int semid){    union semnum sem_num;    if(semctl(semid,0,IPC_RMID,sem_num) == -1)    {        perror("fail sem_del:");    exit(1);    }    return 0;}int p_sem(int semid){    struct sembuf sem;    sem.sem_num = 0;    sem.sem_op = -1;    sem.sem_flg = SEM_UNDO;    if(semop(semid,&sem,1) == -1)    {        perror("fail to p:");    exit(1);    }    return 0;}