[技術] Linux具名管線(FIFOs)編程

Written on 8:39 下午 by Yu Lai

From: http://blog.csdn.net/lcrystal623/archive/2007/03/16/1531201.aspx

具名管線可以用於任何兩個程序間通信，因為有名字可引用。注意管道都是單向的，因此雙方通信需要兩個管道。

下面分別是這兩個程式代碼,同樣是Lucy先運行,然後是Peter。

fifoLucy.c

#include <sys/types.h>
#include <sys/stat.h>

#include <stdio.h>
#include <errno.h>
#include <fcntl.h>
#include <string.h>
#include <unistd.h>
#include <stdlib.h>

int main()
{
 char write_fifo_name[] = "lucy";
   char read_fifo_name[] = "peter";
   int write_fd, read_fd;
   char buf[256];
   int len;
   struct stat stat_buf;

   int ret = mkfifo(write_fifo_name, S_IRUSR | S_IWUSR);
   if( ret == -1) 
 {
    printf("Fail to create FIFO %s: %s",write_fifo_name,strerror(errno));
      exit(-1);
        }

   write_fd = open(write_fifo_name, O_WRONLY);
   if(write_fd == -1) 
 {
    printf("Fail to open FIFO %s: %s",write_fifo_name,strerror(errno));
      exit(-1);
        }
        
   while((read_fd = open(read_fifo_name,O_RDONLY)) == -1) 
 {
    sleep(1);
        }
      
 while(1) 
 {
      printf("Lucy: ");
    fgets(buf, 256, stdin);
      buf[strlen(buf)-1] = '\0';
      if(strncmp(buf,"quit", 4) == 0) 
  {
         close(write_fd);
         unlink(write_fifo_name);
         close(read_fd);
         exit(0);
                }
      write(write_fd, buf, strlen(buf));
      len = read(read_fd, buf, 256);
      if( len > 0) 
  {
       buf[len] = '\0';
         printf("Peter: %s\n", buf);
                }
        }
}

fifoPeter.c

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

int main(void)
{
 char write_fifo_name[] = "peter";
   char read_fifo_name[] = "lucy";
   int write_fd, read_fd;
   char buf[256];
   int len;

   int ret = mkfifo(write_fifo_name, S_IRUSR | S_IWUSR);
   if( ret == -1) 
 {
    printf("Fail to create FIFO %s: %s",write_fifo_name,strerror(errno));
    exit(-1);
    }

   while((read_fd = open(read_fifo_name, O_RDONLY)) == -1) 
 {
  sleep(1);
        }
        
   write_fd = open(write_fifo_name, O_WRONLY);
   if(write_fd == -1) 
 {
    printf("Fail to open FIFO %s: %s", write_fifo_name, strerror(errno));
      exit(-1);
        }

   while(1) 
 {
      len = read(read_fd, buf, 256);
      if(len > 0) 
  {
       buf[len] = '\0';
         printf("Lucy: %s\n",buf);
                }
      printf("Peter: ");
      fgets(buf, 256, stdin);
      buf[strlen(buf)-1] = '\0';
      if(strncmp(buf,"quit", 4) == 0) 
  {
       close(write_fd);
       unlink(write_fifo_name);
         close(read_fd);
         exit(0);
                }
      write(write_fd, buf, strlen(buf));
        }
}

Posted in 技術, IPC, Linux | 0 意見

[技術] Linux Semaphores PV操作程式

Written on 8:36 下午 by Yu Lai

From: http://blog.csdn.net/lcrystal623/archive/2007/03/16/1531189.aspx

多程序實現PV操作，子程序為生產者，倉庫可以容納5個物品，每次檢查倉庫是否滿，若不滿則執行P操作，生產一個物品放入倉庫。父程序檢驗倉庫是否空，若不空則消耗一個物品，執行V操作。sleep函數是隨即設置生產或消費所用時間。

程式主要目的是展示Semaphores的使用，以備以後參考。

#include <stdio.h>
#include <stdlib.h>

#include <sys/ipc.h>
#include <sys/sem.h>
#include <sys/types.h>

int main()
{
 int semID,ret,num;
 int sleepTime;
 struct sembuf buf;
 
 semID = semget(IPC_PRIVATE,1,0666);
 if(semID < 0)
 {
  printf("建立Semaphores出錯\n");
  exit(1); 
 }
 
 if(fork() == 0)
 {  
  while(1)
  {
   num = semctl(semID,0,GETVAL,NULL);
   if(num < 5)
   {
    sleepTime = rand() % 5;
    sleep(sleepTime);
    
    buf.sem_num = 0;
    buf.sem_op = 1;
    buf.sem_flg = 0;
    
    ret = semop(semID,&buf,1);
    if(ret < 0)
    {
     printf("執行P操作失敗！\n");
     exit(1);
    }
    
    num = semctl(semID,0,GETVAL,NULL);
    printf("生產者生產了一個物品放入了倉庫...倉庫中現有物品%d個\n",num);
   }
  }  
 }
 else
 {
  while(1)
  {
   num = semctl(semID,0,GETVAL,NULL);
   if(num > 0)
   {
    sleepTime = rand() % 5;
    sleep(sleepTime);
    
    buf.sem_num = 0;
    buf.sem_op = -1;
    buf.sem_flg = 0;
    
    ret = semop(semID,&buf,1);
    if(ret < 0)
    {
     printf("執行V操作失敗！\n");
     exit(1);
    }
    
    num = semctl(semID,0,GETVAL,NULL);
    printf("消費者從倉庫中消耗了一個物品...倉庫中現有物品%d個\n",num);
   }
  }
 }

 return 0;
}

Posted in 技術, IPC, Linux | 0 意見

[技術] Linux Message Queue程式

Written on 8:23 下午 by Yu Lai

From: http://blog.csdn.net/lcrystal623/archive/2007/03/16/1531183.aspx

檔案msg為空檔案，可以為任何內容，這裡只是為了ftok函數使用。程式透過建立Message Queue，完成程序間通信，注意msgrcv的第四個參數為Message Type，他定義了從Queue中取得Message的Type。

下面是msgLucy.c,是建立Message Queue的

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

#include <stdio.h>
#include <fcntl.h>
#include <signal.h>
#include <stdlib.h>
#include <string.h>

#define PROJID 0xFF
#define LUCY 1
#define PETER 2

int mqid;

void terminate_handler(int signo)
{
 msgctl(mqid,IPC_RMID,NULL);
 exit(0);
}

int main()
{
 char filenm[] = "msg";
 key_t mqkey;
 struct msgbuf 
 {
      long mtype;      /* message type, must be > 0 */
    char mtext[256];  /* message data */
   }msg;
 int ret;

 mqkey = ftok(filenm,PROJID);
 if(mqkey == -1) 
 {
  perror("ftok error: ");
  exit(-1);
 }

 mqid = msgget(mqkey,IPC_CREAT | IPC_EXCL | 0666);
 if(mqid == -1) 
 {
  perror("msgget error: ");
  exit(-1);
 }

 signal(SIGINT, terminate_handler);
 signal(SIGTERM, terminate_handler);

 while(1) 
 {
  printf("Lucy: ");
  fgets(msg.mtext, 256, stdin);
  if (strncmp("quit", msg.mtext, 4) == 0) 
  {
   msgctl(mqid,IPC_RMID,NULL);
   exit(0);
  }
  msg.mtext[strlen(msg.mtext)-1] = '\0';
  msg.mtype = LUCY;
  msgsnd(mqid,&msg,strlen(msg.mtext) + 1,0);
  msgrcv(mqid,&msg,256,PETER,0);
  printf("Peter: %s\n", msg.mtext);  
 }  
}

下面的是msgPeter,是和Lucy通信的,程式先執行Lucy,再執行Peter

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

#include <stdio.h>
#include <fcntl.h>
#include <signal.h>
#include <string.h>
#include <stdlib.h>

#define PROJID 0xFF
#define LUCY 1
#define PETER 2

int main()
{
 char filenm[] = "msg";
 int mqid;
 key_t mqkey;
 struct msgbuf 
 {
         long mtype;      /* message type, must be > 0 */
         char mtext[256];  /* message data */
   }msg;
 int ret;

 mqkey = ftok(filenm, PROJID);
 if(mqkey == -1) 
 {
  perror("ftok error: ");
  exit(-1);
 }

 mqid = msgget(mqkey, 0);
 if(mqid == -1) 
 {
  perror("msgget error: ");
  exit(-1);
 }

 while(1) 
 {
  msgrcv(mqid,&msg,256,LUCY,0);
  printf("Lucy: %s\n",msg.mtext);
  printf("Peter: ");
  fgets(msg.mtext,256,stdin);
  if(strncmp("quit", msg.mtext, 4) == 0) 
  {
   exit(0);
  }
  msg.mtext[strlen(msg.mtext)-1] = '\0';
  msg.mtype = PETER;
  msgsnd(mqid,&msg,strlen(msg.mtext) + 1,0);
 } 
}

Posted in 技術, IPC, Linux | 0 意見

[技術] Linux管線(pipe)程式

Written on 8:07 下午 by Yu Lai

From: http://blog.csdn.net/lcrystal623/archive/2007/03/05/1521168.aspx

管線只能用於父子程序間通信，pipe函式用一個int[]作參數，int[] fd中fd[0]用於讀，fd[1]用於寫。代碼如下：

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>
#include <sys/types.h>

int main()
{
  int pipe1_fd[2], pipe2_fd[2];

      char * parent_talks[] = {"Hi, my baby","Can you tell daddy date and time?","Daddy have to leave here, bye!",NULL};
      char * child_talks[] = {"Hi, daddy","Sure,","Bye!",NULL};

      char parent_buf[256], child_buf[256];
      char * parent_ptr, * child_ptr;

      int i,j, len;
      int child_status;
      time_t curtime;

  if(pipe(pipe1_fd) < 0)
  {
   printf("pipe1 create error\n");
         return -1;
         }

  if(pipe(pipe2_fd) < 0)
         {
       printf("pipe2 create error\n");
       return -1;
         }

      if(fork() == 0)   //child
         {
       //pipe1_fd[0] is used to read, pipe2_fd[1] is used to write
         close(pipe1_fd[1]);
         close(pipe2_fd[0]);

         i = 0;
         child_ptr = child_talks[i];
         while(child_ptr != NULL)
                 {
          len = read(pipe1_fd[0],child_buf,255);
            child_buf[len] = '\0';
            printf("Parent: %s\n",child_buf);

            if(i == 1) 
    {
             time(&curtime);
               len = sprintf(child_buf, "%s %s", child_ptr, ctime(&curtime)); 
               child_buf[len-1] = '\0';
               write(pipe2_fd[1],child_buf,strlen(child_buf));
                         }
            else 
    {
             write(pipe2_fd[1],child_ptr,strlen(child_ptr));
                         }
           
    child_ptr = child_talks[++i];
                 }

         close(pipe1_fd[0]);
         close(pipe2_fd[1]);
         exit(0);
         }
      else   //parent
  {
       //pipe1_fd[1] is used to write, pipe2_fd[0] is used to read
         close(pipe1_fd[0]);
         close(pipe2_fd[1]);

         j = 0;
         parent_ptr = parent_talks[j];
         while(parent_ptr != NULL) 
   {
          write(pipe1_fd[1],parent_ptr,strlen(parent_ptr));
            len = read(pipe2_fd[0],parent_buf,255);
            parent_buf[len] = '\0';
            printf("Child: %s\n", parent_buf);
            parent_ptr = parent_talks[++j];
                 }

         close(pipe1_fd[1]);
         close(pipe2_fd[0]);
         wait(&child_status);
         exit(0);
         }
}

Posted in 技術, IPC, Linux | 0 意見

[技術] Linux Shared Memory程式

Written on 7:40 下午 by Yu Lai

From: http://blog.csdn.net/lcrystal623/archive/2007/03/05/1521158.aspx

要運行程式，需要在當前目錄下建立一個share檔案，share是一個空檔案，沒有任何意義，只是函數ftok需要一個檔案名作參數，ftok另一個參數可以為任何數字。

程式執行後，分為父子程序，子程序申請Shared Memory，然後等待父程序繼續執行，父程序首先等待子程序申請到Shared Memory區段(segment)，然後輸出Shared Memory中的內容，為了演示Shared Memory可以隨時更新，程序中在子程序裡產生隨機數寫入Shared Memory供父程序讀取。
代碼如下：

#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <string.h>

#include <time.h>
#include <signal.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <sys/types.h>

int shmID;
char * buf;
 
void finalize(int signo)
{
 shmctl(shmID,IPC_RMID,NULL);
 
 exit(0);
}

int main()
{
 int i = 1;  
 key_t shmKey;
 
 signal(SIGINT,finalize);
 signal(SIGTERM,finalize);
 
 if(fork() == 0) //子程序
 {  
  shmKey = ftok("share",16);  //可以使用任何大於0的數字，如果名字和數相同，則產生的key相同。
  if(shmKey == -1)
  {
   printf("建立key出錯\n");
   exit(-1);
  }
  
  shmID = shmget(shmKey,20,IPC_CREAT | IPC_EXCL | 0666);
  if(shmID == -1)
  {
   printf("建立Shared Memory Segment出錯\n");
   exit(-1);
  }
  
  sleep(2); //等待父程序執行，好顯示第一行為空。
  while(1)
  {
   buf = (char *)shmat(shmID,NULL,0);
   srandom(time(NULL));
   sprintf(buf,"%d",random()); 
   shmdt(buf);  
  }
 }
 else  //父程序
 {
  sleep(1); //讓子程序先執行，以建立Shared Memory Segment。
  
  shmKey = ftok("share",16);  //可以使用任何大於0的數字，如果名字和數相同，則產生的key相同。
  if(shmKey == -1)
  {
   printf("建立key出錯\n");
   exit(-1);
  }
  
  shmID = shmget(shmKey,20,0); //0表示如果shmKey映射的不存在則報錯。
  if(shmID == -1)
  {
   printf("引用Segment id出錯\n");
   exit(-1);
  }
  
  while(1)
  { 
   buf = (char *)shmat(shmID,NULL,0);
   printf("%d. 現在Shared Memory中的內容為：%s\n",i++,buf);
   shmdt(buf);
   sleep(1);
  }
 } 

 return 0;
}

Posted in 技術, IPC, Linux | 0 意見