西工大2021操作系统实验六openEuler

#include <stdio.h> #include <sys/types.h> #include <sys/ipc.h> #include <unistd.h> #include <stdlib.h> #include <sys/shm.h> #include <string.h> struct shareMemory{ int is_write; char data[20]; }; int main(int argc, const char *argv[]) { key_t key_n ; int shm_id; pid_t pid; int running = 1; //决定是否继续运行的变量 void *shm = NULL; //共享内存的首地址 struct shareMemory *shared; char buf[1024+1]; if((key_n = ftok("/",'s')<0)) //生成共享内存的key值 { perror("Fail to ftok"); exit(EXIT_SUCCESS); } printf("key num:%d\n",key_n); if((shm_id = shmget(key_n,1024,0666|IPC_CREAT))==-1) //创建共享内存 { perror("Fail to shmget"); exit(EXIT_SUCCESS); } printf("share memory id:%d\n",shm_id); if((pid = fork())==-1) { perror("Fail to fork"); exit(EXIT_SUCCESS); } if(pid==0) //子进程，用来读 { printf("I is son process!\n"); shm = shmat(shm_id,0,0); //将共享内存连接到当前进程的地址空间 if(shm==(void *)-1) { perror("Fail to shmat"); exit(EXIT_SUCCESS); } printf(" son Memory attached at %x\n",(int)shm); shared = (struct shareMemory *)shm; //设置共享内存 shared->is_write = 0; while(running) //读取共享内存中的数据 { if(shared->is_write!=0) { printf("YOu worte:%s\n",shared->data); sleep(rand()%3); shared->is_write = 0; if(strncmp(shared->data,"end",3)==0) //输入end退出循环 { running = 0; } else //有其他进程在写数据，不能读 sleep(1); } } if(shmdt(shm)==-1) //把共享内存从当前进程分离 { perror("Fail to shmdt"); exit(EXIT_SUCCESS); } if(shmctl(shm_id,IPC_RMID,0)==-1) //删除这块共享内存 { perror("Fail to shmctl(IPC_RMID)"); exit(EXIT_SUCCESS); } exit(EXIT_SUCCESS); } if(pid!=0) //父进程，用来写 { printf("I is father process:%d\n",pid); shm = shmat(shm_id,0,0); //将共享内存连接到当前进程的地址空间 if(shm==(void *)-1) { perror("Fail to shmat"); exit(EXIT_SUCCESS); } printf("father Memory attached at %x\n",(int)shm); shared = (struct shareMemory *)shm; //设置共享内存 shared->is_write = 0; while(running) //向共享内存中写数据 { while(shared->is_write==1) { printf("wait...\n"); sleep(1); } //向共享内存中写入数据 printf("input some data:\n"); fgets(buf,1024,stdin); strncpy(shared->data,buf,1024); shared->is_write = 1; //写完数据后，置1使可读 if(strncmp(shared->data,"end",3)==0) { running = 0; } } if(shmdt(shm)==-1) //把共享内存从这块进程分离 { perror("Fail to shmdt"); exit(EXIT_SUCCESS); } sleep(2); exit(EXIT_SUCCESS); } return 0; }