南郵作業系統實驗1

實驗1：

運作以下程式，判斷該程式建立了多少程序？

#include <stdio.h>

#include <unistd.h>

main()

{

    pid_t  pid1,pid2;

    pid1=fork();

    pid2=fork();

    printf("pid = %d\n", getpid());

    sleep(20);  //為了觀察

}
           

運作結果截圖

實驗2：

1、父程序建立管道 2、父程序向管道寫入Greetings 3、子程序從管道中讀取消息，并顯示在螢幕上

運作結果截圖

實驗3：

消息緩沖隊列：

編寫程式，利用消息緩沖隊列實作client與server之間的通信

server.c

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/msg.h>
#include <sys/ipc.h>
#define MAXMSZ 250
#define MSGKEY 75
struct mymesg{
  long mtype;
  char mtext[MAXMSZ];
};
int main()
{
  struct mymesg buf;
  int msqid = msgget( MSGKEY,0777|IPC_CREAT);
  int nbytes = sizeof(struct mymesg)-sizeof(int);
  memset(&buf,0x00,sizeof(struct mymesg));
  int mtype = 1;
  int flag = msgrcv( msqid,&buf,nbytes,mtype,0);
  buf.mtype = atol(buf.mtext);
  printf("serving for client.server_pid = %d\n type=%d,message=%d\n",getpid(),mtype,msqid);
  sprintf(buf.mtext,"%d",getpid());
  nbytes = strlen(buf.mtext);
  msgsnd(msqid,&buf,nbytes,0);
  printf("server send message:type=%d text=%s,msglen=%d",(int)buf.mtype,buf.mtext,nbytes);
  sleep(10);
  msgctl(msqid,IPC_RMID,0);
}
           

client.c

#include <stdlib.h>
#include <stdio.h>
#include <unistd.h>
#include <string.h>
#include <sys/types.h>
#include <sys/msg.h>
#include <sys/ipc.h>
#define MAXMSZ 250
#define MSGKEY 75
struct mymesg{
  long mtype;
  char mtext[MAXMSZ];
};
int main()
{
  int qid,nbytes;
  struct mymesg m;
  qid = msgget(MSGKEY,0);
  memset(&m,0,sizeof(m));
  nbytes = strlen(m.mtext);
  m.mtype =1;
  msgsnd(qid,&m,nbytes,0);
  printf("client (pid=%d) send message: type = %ld,text = %d",qid,m.mtype,qid);
  nbytes = sizeof(struct mymesg)-sizeof(int);
  memset(&m,0x00,sizeof(struct mymesg));
  int mtype =getpid();
  int flag =msgrcv(qid,&m,nbytes,mtype,0);
  printf("receive reply from server.type = %d,message = %s",(int)m.mtype,m.mtext);
}
           

運作結果截圖

實驗4：

共享存儲區

用fork()建立子程序，利用共享存儲區實作client和server的通信

#include<sys/types.h>
#include<sys/msg.h>
#include<sys/ipc.h>
#define SHMKEY  75
void CLIENT()
{
int shmid,i;
int *addr;
shmid=shmget(SHMKEY,1024, 0777|IPC_CREAT);
addr=shmat(shmid,0,0);
for(i=9;i>=0;i--)
{while(*addr!= -1);
printf("(client)sent\n");
*addr=i;
}
exit(0);
}
void SERVER()
{
int shmid;
int *addr;
shmid=shmget(SHMKEY,1024,0777|IPC_CREAT);
addr=shmat(shmid,0,0);
*addr=-1;
do
{
while(*addr ==-1);
printf("(server)received\n%d",*addr);
if(*addr!=0)
*addr=-1;
}while(*addr!=0);
wait(0);
shmctl(shmid,IPC_RMID,0);
}
void main()
{
if(fork())
{
SERVER();
}else
{CLIENT();
}
}
           

運作結果截圖