myshell.c

题目：文件系统的模拟实现 目的：深入理解文件系统的实现机制

#include "myfilesys.h"
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

typedef struct command {
  char word[15][15];
  int num;
} Command;

struct {
  char pnstack[15][15];
  char pathname[50];
  int sp;
  
}Default_Dir;

void ls(Command command);
void cd(Command command);
void MKDIR(Command command);
void cat(Command command);
Command GetCommand(const char *string);

Command GetCommand(const char *string)
{
    Command command;
    int i,j=0;
    command.num=0;
    
    for(i=0; ;i++)
      {
          while((*string!=' ') && (*string!='\012'))
	    {
	        command.word[i][j]=*string;
		j++;
		string++;
	    }
	  command.word[i][j]='\0';
	  command.num++;
	  if (*string == '\012')
	    break;
	  string++;
	  j = 0;
      }
    return command;
}

void ls(Command command) 
{
    if (command.num == 1)
        List(Default_Dir.pathname, 0);
    else if (strcmp(command.word[1], "-l") == 0)
        List(Default_Dir.pathname, 1);
    else
        printf("\nError! usage : ls or ls -l\n");
}

void cd(Command command) 
{
    int i;
    char tempname[15], temppathname[50];
    if (command.num != 2) 
        printf("\nError! usage : cd dirname\n");
    else {
        if (strcmp(command.word[1], "..") == 0) {
	  if (Default_Dir.sp != 0) {
	      Default_Dir.sp--;
	      strcpy(Default_Dir.pathname, Default_Dir.pnstack[0]);
	  } 
	  
	  if  (Default_Dir.sp >= 1) 
	      strcat(Default_Dir.pathname, Default_Dir.pnstack[1]);
	  if (Default_Dir.sp >= 2) 
	      for (i = 2; i <= Default_Dir.sp; i++) {
		strcpy(tempname, "/");
		strcat(tempname, Default_Dir.pnstack[i]);
	      //	      printf("nstack[%d]: %s", i, Default_Dir.pnstack[i]); 
	      //	      printf("tempname:%s", tempname); 
		strcat(Default_Dir.pathname, tempname );
		
	      }
	  
	} else if (strcmp(command.word[1], ".") != 0) {
	    strcpy(temppathname, Default_Dir.pathname);
	    if (Default_Dir.sp == 0) 
	        strcat(temppathname, command.word[1]);
	    else
	        strcat(strcat(temppathname, "/"), command.word[1]);
	    if (SearchDir(temppathname) == 0)
	        printf("\ncd():Can't find the dir: %s\n", command.word[1]);
	    else {
	        if (Default_Dir.sp == 0) strcat(Default_Dir.pathname, command.word[1]);
		else {
		  strcat(strcat(Default_Dir.pathname,"/"), command.word[1]);
		}
		
		strcpy(Default_Dir.pnstack[++Default_Dir.sp],  command.word[1]);
	    }
	    
	}
	
    }
    
}


void MKDIR(Command command)
{

    char temppathname[50];
    strcpy(temppathname, Default_Dir.pathname);
    

    if (Default_Dir.sp == 0) 
        strcat(temppathname, command.word[1]);
    else    
        strcat(strcat(temppathname, "/"), command.word[1]);
    
    if (command.num != 2)
        printf("\nError! usage: mkdir filename\n");
    else {
	mymkdir(temppathname);
    }
}

void cat(Command command)
{
    int fd,n;
    char string[1024],temppathname[50];
    
    strcpy(temppathname, Default_Dir.pathname);
    
  if((strcmp(command.word[1], ">") == 0))
    {
      
  if (Default_Dir.sp == 0) 
      strcat(temppathname, command.word[2]);
  else    
      strcat(strcat(temppathname, "/"), command.word[2]);
  
  fd=Open(temppathname, O_RDWR|O_CREAT, 0644 );
  if(fd<0)
    {
	 printf("the file not exist\n");
    }
  else
    {
	  scanf("%s", string);
	  getchar();
	  Write(fd,string,1024);
	  
       }
    }
  else
    {
      if (Default_Dir.sp == 0) 
	strcat(temppathname, command.word[1]);
      else    
	strcat(strcat(temppathname, "/"), command.word[1]);
      
      fd=Open(temppathname, O_RDONLY);
      

      if(fd<0)
	{
	  printf("the file not exist\n");
	}
      else
	{
	  while(1)
	    {n=Read(fd,string,1024);
	    if(n<=0)
	      break;
	    printf("%s\n",string);
	    }
	}
    }
  Close(fd);  
  
}




int  main(void)
{
    char string[50];
    int i;
    Command command;
    
    
    strcpy(Default_Dir.pnstack[0],"/");  //init Default_Dir
    strcpy(Default_Dir.pathname,"/");
    Default_Dir.sp = 0;
    
    while (1) {

        printf("[myshell@%s]$", Default_Dir.pathname);
	
	i = 0;
	while(1)
	  {
	    string[i] = getchar();
	    if(string[i]=='\012')
	      break;
	    i++;
	  }
	
	command = GetCommand(string);
	/*
	  for (i = 0; i < command.num; i++) 
	  printf("num: %d, word[%d]:%s\n", command.num, i, command.word[i]); 
	*/
	if (strcmp(command.word[0], "ls") == 0) 
	  ls(command);
	else if (strcmp(command.word[0], "mkdir") == 0)
	  MKDIR(command);
	else if (strcmp(command.word[0], "cd") == 0)
	  cd(command);
	else if (strcmp(command.word[0], "cat") == 0)
	  cat(command);
	else if (strcmp(command.word[0], "exit") == 0){
	  Over();
	  break;
	} else 
	  printf("-myshell: %s : command not found.\n", command.word[0]);
	
    }

    printf("\n\n\n\n\n\n\n\n         Thank you for using!\n\n\n             ---------Copyright (c) 2005.1.9 HGMJCL Team. All rights reserved!\n\n\n\n\n\n\n\n\n\n\n\n");

    return 0;
}