169 lines
3.6 KiB
C
169 lines
3.6 KiB
C
/*************************************************************************
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> File Name : ipc_share_mem_server.c
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> Author : TL Song
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> EMail : songtianlun@frytea.com
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> Created Time : Mon 28 Dec 2020 03:55:22 PM CST
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************************************************************************/
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#include<stdio.h>
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#include<stdlib.h>
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#include<sys/shm.h> // shared memory
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#include<sys/sem.h> // semaphore
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#include<sys/msg.h> // message queue
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#include<string.h> // memcpy
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// 消息队列结构
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struct msg_form {
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long mtype;
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char mtext;
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};
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// 联合体，用于semctl初始化
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union semun
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{
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int val; /*for SETVAL*/
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struct semid_ds *buf;
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unsigned short *array;
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};
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// 初始化信号量
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int init_sem(int sem_id, int value)
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{
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union semun tmp;
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tmp.val = value;
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if(semctl(sem_id, 0, SETVAL, tmp) == -1)
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{
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perror("Init Semaphore Error");
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return -1;
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}
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return 0;
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}
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// P操作:
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// 若信号量值为1，获取资源并将信号量值-1
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// 若信号量值为0，进程挂起等待
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int sem_p(int sem_id)
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{
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struct sembuf sbuf;
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sbuf.sem_num = 0; /*序号*/
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sbuf.sem_op = -1; /*P操作*/
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sbuf.sem_flg = SEM_UNDO;
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if(semop(sem_id, &sbuf, 1) == -1)
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{
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perror("P operation Error");
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return -1;
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}
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return 0;
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}
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// V操作：
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// 释放资源并将信号量值+1
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// 如果有进程正在挂起等待，则唤醒它们
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int sem_v(int sem_id)
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{
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struct sembuf sbuf;
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sbuf.sem_num = 0; /*序号*/
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sbuf.sem_op = 1; /*V操作*/
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sbuf.sem_flg = SEM_UNDO;
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if(semop(sem_id, &sbuf, 1) == -1)
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{
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perror("V operation Error");
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return -1;
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}
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return 0;
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}
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// 删除信号量集
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int del_sem(int sem_id)
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{
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union semun tmp;
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if(semctl(sem_id, 0, IPC_RMID, tmp) == -1)
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{
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perror("Delete Semaphore Error");
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return -1;
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}
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return 0;
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}
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// 创建一个信号量集
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int creat_sem(key_t key)
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{
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int sem_id;
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if((sem_id = semget(key, 1, IPC_CREAT|0666)) == -1)
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{
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perror("semget error");
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exit(-1);
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}
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init_sem(sem_id, 1); /*初值设为1资源未占用*/
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return sem_id;
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}
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int main()
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{
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key_t key;
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int shmid, semid, msqid;
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char *shm;
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char data[] = "this is server";
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struct shmid_ds buf1; /*用于删除共享内存*/
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struct msqid_ds buf2; /*用于删除消息队列*/
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struct msg_form msg; /*消息队列用于通知对方更新了共享内存*/
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// 获取key值
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if((key = ftok(".", 'z')) < 0)
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{
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perror("ftok error");
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exit(1);
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}
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// 创建共享内存
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if((shmid = shmget(key, 1024, IPC_CREAT|0666)) == -1)
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{
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perror("Create Shared Memory Error");
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exit(1);
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}
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// 连接共享内存
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shm = (char*)shmat(shmid, 0, 0);
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if((int)shm == -1)
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{
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perror("Attach Shared Memory Error");
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exit(1);
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}
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// 创建消息队列
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if ((msqid = msgget(key, IPC_CREAT|0777)) == -1)
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{
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perror("msgget error");
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exit(1);
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}
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// 创建信号量
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semid = creat_sem(key);
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system("/proc/$$/ns");
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// 读数据
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while(1)
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{
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msgrcv(msqid, &msg, 1, 888, 0); /*读取类型为888的消息*/
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if(msg.mtext == 'q') /*quit - 跳出循环*/
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break;
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if(msg.mtext == 'r') /*read - 读共享内存*/
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{
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sem_p(semid);
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printf("%s\n",shm);
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sem_v(semid);
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}
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}
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// 断开连接
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shmdt(shm);
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/*删除共享内存、消息队列、信号量*/
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shmctl(shmid, IPC_RMID, &buf1);
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msgctl(msqid, IPC_RMID, &buf2);
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del_sem(semid);
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return 0;
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}
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