fat.txt

FAT 文件系统半成品

            {
               read(filedes,&newFat,sizeof(FAT));//读取fat
               if(newFat.nextBlock==-2)
                  break;
            }
            //若没有找到空闲块,则结束写入
            //************
			if(newFatPos==BLOCK_NYM) 
				
				break;
            //将当前块的fat值改为新块的块号
            //************
			fat.nextBlock=newFatPos;
            //将新块的fat值改为-1,表明这是文件的最后一块
            //************
			newFat nextBlock=-1;
			lseek(filedes,volumeInfo.fatAreaAddress+newFatPos*sizeof(FAT),SEEK_SET);
		    write(filedes,&newFat,sizeof(FAT));
            //当前块号改为新块的块号
			//************
            block=newFatPos;
         }
         else
         {
            //将当前块号,改为下一块的块号
            //************
			block=fat.nextBlock;
         }
         //块内偏移blockPos,设置到块首
         //************
		 blockPos=0;
     }
     //在当前块的块内偏移位置写入数据
     //************
	 lseek(filedes,volumeInfo.dataAreaAddress+block*BLOCK_SIZE+blockPos,SEEK_SET);
	 write(filedes,buf+finishNum);
     blockPos++;
     finishNum++;
  }
  //修改文件描述信息中的文件的大小
  //************
  if(finshNum+writePos>fcb.size)
  {
  fcb.size=finishNum+writePos;
  lseek(filedes,volumeInfo.fcbAreaAddress+fcbPos*sizeof(FCB),SEEK_SET);
  write(filedes,&fcb,sizeof(FCB));
  }//返回实际写入的数据量
  return finishNum;
}
//读文件。fileName是要执行操作的文件名,buf是存放读出的数据的数组
//readNum是要读取的数据量,readPos是读取位置
//返回值是实际读出的数据量
long readFile (char* fileName,char* buf,long readNum,long readPos)
{
  FCB fcb;//文件描述信息
  long block;//当前块号
  long blockPos;//块内偏移
  long finishNum;
  FAT fat;
  long fcbPos =openFile(fileName,&fcb);
  if(readPos>fcb.size)
  {
   readPos=fcb.size;
  }
  block=fcb.headBlock;
  blockPos=readPos%BLOCK_SIZE;
  finishNUM=0;
  long moveTime;// block要移动的次数
  //计算block要移动的次数moveTime
  //例如：若writePos=510,则要将block要移动到该文件的第1个盘块，需移动0次, moveTime=0
  //若writePos=600,则要将block移动到该文件的第2个盘块，需移动1次, moveTime=1
  //************
  moveTime=writePos/BLOCK_SIZE;
  //移动block
  while(moveTime >0)
  {
     //读取当前块的fat值，获取下一块的块号
     //************
	  lseek(filedes,volumeInfo.fatAreaAddress+block*sizeof(fat),SEEK_SET);
	  read(filedes,&fat,sizeof(FAT));
     //将block移动到下一块号
     //************
	 block=fat.nextBlock;
     moveTime --;
	}
  while(finishNum<readNum)
  {
      lseek(filedes,volumeInfo.dataAreaAddress+block*BLOCK_SIZE+blockPos,SEEK_SET);
	  read(filedes,&buf,sizeof(FAT))
	 blockPos++;
     finishNum++;

  }
  return  readNum;
}
//******************************************************************************
//以下我的框架部分 主要是把返回值定为long 如果不成功则返回-1

//创建文件夹.  meunName是要创建的文件夹名
long  mkdir(char *meunName)
{

  //***********

}

long  rmdir(char *meunName)
{
   //*************
}

void cd()
{
 //***************
}

long inFile(char  *fileName)
{ 

//*******************
}

long outFile(char  *fileName)
{

  //***************
}


long remeunName(char *meunName,char *newmeunName)
{

	//************
}


long refileName(char *fileName,char  *newfileName)
{
     FCB fcb;  //文件描述信息
     long block;  //当前块号
    long blockPos;  //块内偏移
     long finishNum;  //记录已经写入的数据量
     FAT fat;
	 long fcbPos =openFile(fileName,&fcb);


	 
	//*************
}

long lsFile(char *fileName)
{

	//*******************
}

void clear()
{
	system("clear");
}


void cd_back()
{

	//***********************
}


//主函数
int main()
{ 
  cout<<"******Welcome to Virtual File System V1******"<<endl;//输出欢迎信息
  version();打印信息 
  
  filedes=open("mydisk",O_RDWR|O_CREAT); //打开模拟文件系统的文件
  //检查存储介质是否已经被格式化
  lseek(filedes,0,SEEK_SET);//将读写指针移动到盘卷总信息处
  //读取盘卷总信息
  if(read(filedes,&volumeInfo,sizeof(VolumeInfo))<sizeof(VolumeInfo))
  {
     cout<<"the Virtual File System is unformated!"<<endl;
	 cout<<"格式化将删除磁盘上所有资料，是否继续?<Y/N>:"
     if (getchar()!='y'&&getchar()!='Y')
			return 0;
	 else 
          format();
  }
  else if(volumeInfo.fcbAreaAddress!=sizeof(VolumeInfo) ||
          volumeInfo.fatAreaAddress!=volumeInfo.fcbAreaAddress+sizeof(FCB)*FCB_NUM ||
          volumeInfo.dataAreaAddress!=volumeInfo.fatAreaAddress+sizeof(FAT)*BLOCK_NUM)
  {
     cout<<"the Virtual File System is unformated!"<<endl;
     format();
  }
  //循环处理用户输入的操作命令
  while(true)
  {
     getCommand();//显示命令提示符,并接收用户输入的命令
     //处理用户命令
     if(strcmp(command[0],"exit")==0)
     {
        return 0;//退出程序
     }
     else if(strcmp(command[0],"help")==0)
     {
        showHelp();//显示帮助
     }
     else if(strcmp(command[0],"format")==0)
     {
        format();//格式化虚拟文件系统
     }
     else if(strcmp(command[0],"showVolumeInfo")==0)
     {
        showVolumeInfo();//显示盘卷总信息
     }
     else if(strcmp(command[0],"ls")==0)
     {
        ls();//显示目录内容
     }
     else if(strcmp(command[0],"createFile")==0)
     {
        if(commandNum<2)
        {
           cout<<"this command must take a argument!"<<endl;
           continue;
        }
        createFile (command[1]);//建立文件
     }
     else if(strcmp(command[0],"deleteFile")==0)
     {
        if(commandNum<2)
        {
           cout<<"this command must take a argument!"<<endl;
           continue;
        }
        deleteFile (command[1]);//删除文件
     }
     else if(strcmp(command[0],"writeFile")==0)
     {
        if(commandNum<3)
        {
           cout<<"this command must take two argument!"<<endl;
           continue;
        }
        writeFile (command[1],command[2],sizeof(command[2]),0);//写入文件
     }
     else if(strcmp(command[0],"readFile")==0)
     {
        if(commandNum<2)
        {
           cout<<"this command must take a argument!"<<endl;
           continue;
        }
        char buf[100]; 
        readFile (command[1],buf,100,0);//读文件
        cout<<buf<<endl;//输出文件内容
     }
	 else if(strcmp(command[0],"clear")==0)
	 {
		 clear();                    //清屏
	 }
     else if(strcmp(command[0],"mkdir")==0)
     {
		 if(commandNum<2)
		 {
			 cout<<"this command must take a argument!"<<endl;
           continue;
		 }
		 mkdir(command[1]);
        
     }
	 else if(strcmp(command[0],"rm")==0)
	 {
		 if(commandNum<2)
		 {
			 cout<<"this command must take a argument!"<<endl;
           continue;
		 }
		 rm(command[1]);
	 }
	 else if(strcmp(command[0],"outFile")==0)
	 {
		 if(commandNum<2)
        {
           cout<<"this command must take a argument!"<<endl;
           continue;
        }
		 outFile(command[1]);
	 }
     
	 else if(strcmp(command[0],"inFile")==0)
	 { if(commandNum<2)
        {
           cout<<"this command must take a argument!"<<endl;
           continue;
        }
	    inFile(command[1]);
	 }
     else if(strcmp(command[0],"cd..")==0)
	 {
	    cd_back();
	 }
	 else if(strcmp(command[0],"cd")==0)
	 { if(commandNum<2)
        {
           cout<<"this command must take a argument!"<<endl;
           continue;
        }
	    cd(command[1]);
	 }
     else  if(strcmp(command[0],"remeunName")==0)
     { if(commandNum<3)
        {
           cout<<"this command must take two argument!"<<endl;
           continue;
        }
	    remeunName(command[1],command[2]);
	 }
	 else  if(strcmp(command[0],"refileName")==0)
     { if(commandNum<3)
        {
           cout<<"this command must take two argument!"<<endl;
           continue;
        }
	    refileName(command[1],command[2]);
	 }
	  else  if(strcmp(command[0],"lsFile")==0)
     { if(commandNum<2)
        {
           cout<<"this command must take a argument!"<<endl;
           continue;
        }
	    lsFile(command[1]);
	 }
     else

     {
        cout<<"Command Not Found!"<<endl;
     }
  }
  return 0;
}