[Linux學習]Linux下進程通訊之訊息佇列

本文做了一個簡單的樣本來介紹Linux下訊息佇列，共有兩段代碼，類比阻塞式聊天，下面看代碼吧！

msgServer.c

#include <stdio.h>  
#include <fcntl.h>  
#include <stdlib.h>  
#include <sys/types.h>  
#include <sys/ipc.h>  
#include <sys/msg.h>  
#include <sys/stat.h>  

#define BUF_SIZE   256  
#define PROJ_ID    32  
#define PATH_NAME  "/tmp"  
#define SERVER_MSG 1  
#define CLIENT_MSG 2  

int main(void){  
/*使用者自訂訊息緩衝區*/  
struct mymsgbuf{  
long msgtype;  
char ctrlstring[BUF_SIZE];  
} msgbuffer;  
int qid;  
int msglen;  
key_t msgkey;  

/*擷取索引值*/  
if((msgkey=ftok(PATH_NAME,PROJ_ID))==-1)  
{  
      perror("ftok error!\n");  
      exit(1);  
}  

/*擷取訊息佇列標識符*/  
if ((qid = msgget(msgkey,IPC_CREAT|0660)) == -1)  
{  
      perror("msgget error!\n");  
      exit(1);  
}  

while(1)  
{  
  printf("server:");  
  fgets(msgbuffer.ctrlstring,BUF_SIZE, stdin);  
if(strncmp("exit",msgbuffer.ctrlstring,4)==0)     
  {      
    msgctl(qid,IPC_RMID,NULL);  
break;  

  }  
  msgbuffer.ctrlstring[strlen(msgbuffer.ctrlstring) - 1] = '\0';  
  msgbuffer.msgtype = SERVER_MSG;  
if (msgsnd(qid,&msgbuffer,strlen(msgbuffer.ctrlstring) + 1,0) == -1)  
  {  
    perror("Server msgsnd error!\n");  
    exit(1);  
  }  

if (msgrcv(qid,&msgbuffer,BUF_SIZE,CLIENT_MSG,0) == -1)  
  {  
    perror("Server msgrcv error!\n");  
    exit(1);  
  }  
  printf("Client: %s\n",msgbuffer.ctrlstring);  
}  
exit(0);  
}  

msgclient.c

#include <stdio.h>  
#include <fcntl.h>  
#include <stdlib.h>  
#include <string.h>  
#include <sys/types.h>  
#include <sys/ipc.h>  
#include <sys/msg.h>  
#include <sys/stat.h>  

#define BUF_SIZE    256  
#define PROJ_ID     32  
#define PATH_NAME   "/tmp"  
#define SERVER_MSG 1  
#define CLIENT_MSG 2  

int main(void)  
{  

/*使用者自訂訊息緩衝區*/  
struct mymsgbuf{  
long msgtype;  
char ctrlstring[BUF_SIZE];  
}msgbuffer;  
int qid;/*訊息佇列標識符*/  
int msglen;  
key_t msgkey;  

/*擷取索引值*/  
if ((msgkey = ftok(PATH_NAME,PROJ_ID)) == -1)  
    {  
      perror("ftok error!\n");  
      exit(1);  
    }  

if ((qid = msgget(msgkey,IPC_CREAT|0660)) == -1)  
    {  
      perror("msgget error!\n");  
      exit(1);  
    }  

while(1)  
    {  
if (msgrcv(qid,&msgbuffer,BUF_SIZE,SERVER_MSG,0) == -1)  
/*if queue is empty, block here*/  
      {  
           perror("Server msgrcv error!\n");  
           exit(1);  
      }  

      printf("server: %s\n",msgbuffer.ctrlstring);  
      printf("client:");  
      fgets(msgbuffer.ctrlstring,BUF_SIZE,stdin);  
if (strncmp("exit",msgbuffer.ctrlstring,4) == 0)  
      {  
break;  
      }  

      msgbuffer.ctrlstring[strlen(msgbuffer.ctrlstring)-1] = '\0';  
      msgbuffer.msgtype = CLIENT_MSG;  
if (msgsnd(qid,&msgbuffer,strlen(msgbuffer.ctrlstring) + 1,0) == -1)  
      {   
          perror("client msgsnd error!\n");  
          exit(1);  
      }  
    }  
   exit(0);  
}