客户端/服务器打印数组并写回

Question

我正在使用 C 和 putty 编写客户端/服务器程序。两个 c 文件位于同一系统上。

我目前在向客户端写回其正在使用的框架以及打印我的框架时遇到问题。它打印出 3 0 9 8，但随后开始打印 13456756 等。

这是我所拥有的:

服务器:

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


    main (void)
    {
      int to_server;    // to read from client
      int from_server;  // to write to client
      int finish;   // lets me know that client is done
      int i,j,k,m,l;    // because C needs this defined as int
      int numClient;// number of clients
      char temp[14];
      int page_size = 128;
      int pages_left;
      int max_frames=10;
      int used_frames =0;
      int frameUpdate=0;
      int freeframe[10] = {3,0,9,8,7,5,1,4,2,6};  //this is the array 
      int numpage=0;
      int frames;
      int check;
      int option;
      int byte;
      int getPage;
      int getOffset;
      int physical_Addr;
      int offset;
      int req[3];
      int again;

      struct values{
          char privFifo[14];
          int memoryreq;
      }cinput;


      /* Create the fifos and open them  */
      if ((mkfifo("FIFO1",0666)<0 && errno != EEXIST))
        {
        perror("cant create FIFO1");
        exit(-1);
        }
      if((to_server=open("FIFO1", O_RDONLY))<0){
           printf("cant open fifo to write");
      }

      //get number of clients
      printf("\nHow many clients?\n");
      scanf("%d", &numClient);

      for(j =1; j <= numClient; j++){
          read(to_server, &cinput, sizeof(cinput));
          printf("\n\nFifo_%d \nMemory request %d", &cinput.privFifo, cinput.memoryreq);
          req[j-1] = cinput.memoryreq;
          if((mkfifo(cinput.privFifo,0666)<0 && errno != EEXIST))
           {
            perror("cant create privFifo");
            exit(-1);
          }

          if((from_server=open(cinput.privFifo, O_WRONLY)<0)){
                  printf("cant open fifo to write");
          }

          // find number of pages need for request
          numpage = cinput.memoryreq/page_size;

          if((numpage * page_size) < cinput.memoryreq){
            numpage++;
          }

          sleep(1);
          printf("\nPages needed %d", numpage);
          write(from_server, &numpage, sizeof(numpage));

          printf("\n******Main Memory******");
          for(m = used_frames; m < numpage; m++){
          printf("\n* client: %d\tframe: %d", j, freeframe[m]);
          frames = freeframe[m];
          write(from_server, &frames, sizeof(frames));
          }

          used_frames = max_frames - used_frames;
          pages_left = max_frames - numpage;

//this is where I try to print out the available frames
          printf("\n Frames available:");
          for(l = pages_left; l!= 0; l--){
                check = max_frames - l;
                printf(" %d", freeframe[check]);
                max_frames = check;
            }
          close(from_server);
          unlink(cinput.privFifo); 
      }

      printf("\nDONE!!!");
      close(to_server);
      unlink("FIFO1");

客户:

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

main (void)
{
  int to_server;    // to write to server
  int from_server;
  char temp[14];    // server puts string here
  int clientID;
  //int frames;
  int numpage;
  int i;

struct values{
    char privFifo[14];
    int memoryreq;
}cinput;

  if((to_server=open("FIFO1", O_WRONLY))<0)
     printf("cant open fifo to write\n");

  printf("writing data to to_server\n");
  printf("Client: Please enter number of memory units: ");
  scanf("%d", &cinput.memoryreq);
  printf("%d", cinput.memoryreq);
  clientID = getpid();
  sprintf(cinput.privFifo, "Fifo_%d", getpid());
  printf("\nFifo name is %s", &cinput.privFifo);
  write(to_server, &cinput, sizeof(cinput));//write client pid and memUnit to server
  sleep(2); //give time to send
  printf("\nClient: Got the character sent, now waiting for response ");

   if ((mkfifo(cinput.privFifo,0666)<0 && errno != EEXIST))
    {
    perror("cant create FIFO1");
    exit(-1);
    }
  if((from_server=open(cinput.privFifo, O_RDONLY))<0){
       printf("cant open fifo to write");
  }
  read(from_server, &numpage, sizeof(numpage));
  printf("\nFrames Occupied %d", numpage);

  close(to_server);
  close (from_server);
  unlink(cinput.privFifo);

  printf ("\nall done!\n");

}

非常感谢任何帮助。谢谢。

Answer 1

我强烈怀疑问题出在 used_frames = max_frames - used_frames; 行上。自 used_frames最初为 0，这将其设置为第二次迭代中超出数组末尾的值，因此当您运行 for(m = used_frames; m < numpage; m++) 时，您开始打印超出帧数组末尾的值。 。 (顺便说一句:请正确缩进。)。但可以设置断点并在调试器中运行以确保确定。