Linux进程通信——消息队列

总结下别人比较好的博文+自己写的一个栗子

1.ftok()   

https://blog.csdn.net/u013485792/article/details/50764224                                                    

2.msgget，msgctl，msgsnd，msgrcv函数

https://blog.csdn.net/guoping16/article/details/6584024

3.一个栗子

/*************************************************************************
    > File Name: show.c
    > Author:  
    > Mail:    
    > Created Time: Wed 24 Oct 2018 12:28:25 PM UTC
 ************************************************************************/
               
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#include<sys/types.h>
#include<sys/msg.h>
#include<unistd.h>
#include<time.h>
#include<sys/ipc.h>
#include<errno.h>
void msg_show(int msg_id, struct msqid_ds msg_info) {
    int ret = -1;
    sleep(1);  
    ret = msgctl(msg_id, IPC_STAT, &msg_info);
    if(-1 == ret) {
        printf("消息获取失败\n");
        perror("error");
        return;
    }         
    printf("\n队列中字节数：%ld\n",msg_info.msg_cbytes);
    printf("队列中消息数：%d\n",(int)msg_info.msg_qnum);
    printf("队列中的最大字节数：%d\n",(int)msg_info.msg_qbytes);
    printf("最后发送消息的进程：%d\n",msg_info.msg_lspid);
    printf("最后接受消息的进程：%d\n",msg_info.msg_lrpid);
    printf("最后发送消息的时间：%s",ctime(&(msg_info.msg_stime)));
    printf("最后接受消息的时间：%s",ctime(&(msg_info.msg_rtime)));
    printf("最后变化的时间：%s",ctime(&(msg_info.msg_ctime)));
    printf("消息UID：%d\n",msg_info.msg_perm.uid);
    printf("消息GID：%d\n\n",msg_info.msg_perm.gid);
}              
               
int main() {   
    int ret = -1;
    int msg_flags,msg_id;
    key_t key;
    struct msgmbuf {
        long mtype;
        char mtext[10];
    };         
    struct msqid_ds msg_info;
    struct msgmbuf msg_mbuf;
    msg_mbuf.mtype = 10;
               
    int msg_sflags,msg_rflags;
    char *msgpath = "/home/whiskey/study/进程/msgque";
    key = ftok(msgpath, 'b');
    if(-1 != key) {
        printf("成功建立KEY\n");
    }         
    else {     
        printf("建立KEY失败\n");
        perror("error:");
    }          
    msg_flags = IPC_CREAT|IPC_EXCL;
    msg_id = msgget(key, msg_flags|0x0666);
    if(-1 == msg_id) {
        printf("消息建立失败\n");
        return 0;
    }          
    else {    
        printf("消息建立成功\n");
    }          
    msg_show(msg_id, msg_info);
    msg_sflags = IPC_NOWAIT;
               
    memcpy(msg_mbuf.mtext, "123", sizeof("123"));
    ret = msgsnd(msg_id, &msg_mbuf, sizeof("123"), msg_flags);
              
    if(-1 == ret) {
        perror("发送消息失败:");
    }         
    msg_show(msg_id, msg_info);
              
    msg_rflags = IPC_NOWAIT|MSG_NOERROR;
    ret = msgrcv(msg_id, &msg_mbuf, 10, 10, msg_rflags);
               
    if(-1 == ret) {
        perror("接收消息失败:");
    }        
    else {   
        printf("接受消息成功,长度：%d\n",ret);
    }        
    msg_show(msg_id, msg_info);
 
    msg_info.msg_perm.uid = 8;
    msg_info.msg_perm.gid = 8;
    msg_info.msg_qbytes = 12345;
    ret = msgctl(msg_id, IPC_SET, &msg_info);
    if(-1 == ret) {
        perror("设置消息属性失败:");
        return 0;
    }        
 
    msg_show(msg_id, msg_info);
 
    ret = msgctl(msg_id, IPC_RMID, NULL);
 
    if(-1 == ret) {
        perror("删除失败:");
        return 0;
    }        
    return 0;
 
}

运行时需要root权限，记得加sudo

编译时曾遇到的错误：

msgecv函数No message of desired type

原因：msgmbuf中mtype开始时我设置的是int类型，应该是long类型