进程通信方式--共享内存（shm)--实现自由通信

//欢迎大家评论提出意见#include"utili.h"#include<stdio.h>#include<stdlib.h>#include<unistd.h>#include<sys/sem.h>#include<sys/types.h>#include<sys/shm.h>#include<sys/ipc.h>#include<string.h>#include<sys/msg.h> union semun{        int              val;    /* Value for SETVAL */        struct semid_ds *buf;    /* Buffer for IPC_STAT, IPC_SET */        unsigned short  *array;  /* Array for GETALL, SETALL */        struct seminfo  *__buf;  /* Buffer for IPC_INFO                                    (Linux-specific) */};//.........ser.c#include"utili.h"int main(){    key_t shm_key = ftok("myshm",0xff);    if(shm_key == -1)      {         perror("ftok shm_key");         exit(1);      }    //shmget函数  用于创建或打开一个共享内存     int shm_id = shmget(shm_key,1024,IPC_CREAT|0755);     if(shm_id == -1)      {         perror("shmget");         exit(1);      } //void *shmat(int dhmid,int cmd,stuct dhmid_ds *buf);    //shmat 连接共享内存与某个进程的地址空间     void *shm_addr = shmat(shm_id,NULL,0);      if(shm_addr == (void*)-1)       {          perror("shmat");          shmctl(shm_id,IPC_RMID,NULL);          exit(1);       }     //加入信号量，实现通信    key_t sem_key = ftok("mysem",0xfe);//semget -创建一个新信号量或者取得一个现有的信号量    int sem_id = semget(sem_key,2,IPC_CREAT|IPC_EXCL|0755);    union semun init_val;    init_val.val = 0;    semctl(sem_id,0,SETVAL,init_val);    semctl(sem_id,1,SETVAL,init_val);    struct sembuf p = {1,-1,0},                  v = {0, 1,0};       while(1)      {          printf("Ser:>");          scanf("%s",(char*)shm_addr);          if(strcmp((char*)shm_addr,"quit") == 0)            {   // shmdt()-当进程完成某个共享内存区的使用时，调用此函数断接内存区               shmdt(shm_addr);               shmctl(shm_id,IPC_RMID,NULL);               break;             }           semop(sem_id,&v,1);//           semop(sem_id,&p,1);           printf("Cli:>%s\n",(char*)shm_addr);      }       return 0;}//..................cli.c#include"utili.h"int main(){    key_t shm_key = ftok("myshm",0xff);    if(shm_key == -1)    {        perror("ftok shm_key");        exit(1);    }    //shm_id  用于创建或打开一个共享内存    int shm_id = shmget(shm_key,0,0);    if(shm_id == -1)    {        perror("shmget");        exit(1);    }    //shmat  断接内存区    void *shm_addr = shmat(shm_id,NULL,0);    if(shm_addr == (void*)-1);    {        perror("shmat");    //    shmctl(shm_id,IPC_RMID,NULL);        exit(1);    }    //加入信号量，实现通信    key_t sem_key = ftok("myshm",0xfe);    int sem_id = semget(sem_key,0,0);    struct sembuf p = {1,-1,0},                  v = {0,1,0};    while(1)    {                semop(sem_id,&p,1);        printf("Ser:>%s\n",(char*)shm_addr);                printf("Cli:>");        scanf("%s",(char*)shm_addr);        if(strcmp((char*)shm_addr,"quit") == 0)        {            shmdt(shm_addr);            //shmctl(shm_id,IPC_RMID,NULL);            break;        }        semop(sem_id,&v,1);    }    return 0;}