s.c

在linux平台上实现两个进程之间的交互。一客户进程向一远程进程提交一道作业；远程进程完成作业后向客户进程返回执行结果或者是结束的信息。

# include <unistd.h>
# include <stdio.h>          /*sever process*/
# include <sys/msg.h>
# include <sys/types.h>
# include <sys/ipc.h>
# include <sys/wait.h>
# include <string.h>
# define msgkey 181
struct mymsgform{
                long mtype;
                char mpath[250];
                }msg;
int open_queue(key_t keyval)
{
int qid;
 if ((qid=msgget(msgkey,IPC_CREAT|0660))==-1)
 {
 return(-1);
 }
 return(qid);

}
int send_message(int qid,struct mymsgform*msg)
{
  int result,length;
  length=sizeof(struct mymsgform)-sizeof(long);
  if ((result=msgsnd(qid,msg,length,0))==-1)
     {
     return(-1);
     }
     return(qid);
}
int read_message(int qid,long type,struct mymsgform*msg)
{
  int result,length;
  length=sizeof(struct mymsgform)-sizeof(long);
  if ((result=msgrcv(qid,msg,length,type,0))==-1)
     {
     return(-1);
     }
     return(result);
}

main()
{
 int qid,pid,abc,status1;
 pid_t pid1;
 printf("(s)Be ready to receive a message!\n");
 if ((qid=open_queue(msgkey))==-1)
    {
    perror("open_queue");
    exit(1);
    }      /*CREATE A MESSAGE QUEUE*/
  printf("(s)creat a message queue,its keyvalue is %d\n",msgkey);
  pid=getpid();
  printf("(s)The process id is %d\n",pid);
 msg.mtype=1;
 while (abc=read_message(qid,msg.mtype,&msg)==-1)
  { }
 printf("(s)receive a message!\n");
 pid1=fork();
 if (pid1>0)
 {
  printf("(s)now child run the other program!\n");
  execl(msg.mpath,(char*)0);
  waitpid(pid1,&status1,0);
 }else
 {
 send_message(qid,&msg);
 printf("(s)sever had finished the work!\n");
 exit(1);}
 if (msgctl(qid,IPC_RMID,0)==-1)
 {
  printf("(s)the message could not be removed!");
 }
}