os.cpp

操作系统课程设计 1、模拟UNIX(linux)文件系统 [问题描述] 在任一OS下

type为1时，写文件；
type为2时，写磁盘块
该函数只有在创建和删除时才调用
****************************************************************************************************************/
void write_bit(int pos,int type)                   
{                                                  
	if(type==0)                                   
	{                                             
		fseek(fp,sizeof(int)*(pos+3),SEEK_SET);    
		fwrite(&dir_flag[pos],sizeof(int),1,fp);
	}
	else if(type==1)
	{
		fseek(fp,sizeof(int)*(DIR_NUM+pos+3),SEEK_SET);
		fwrite(&file_flag[pos],sizeof(int),1,fp);
	}
	else
	{		
		fseek(fp,sizeof(int)*(DIR_NUM+FILE_NUM+pos+3),SEEK_SET);
		fwrite(&block_flag[pos],sizeof(int),1,fp);
	}
}

/***************************************************************************************************************
//写回目录或文件节点的控制信息 
//type为0时，写目录
//type为1时，写文件
//有目录或文件的控制信息被修改，该函数就被调用
****************************************************************************************************************/
void write_inode(int pos,int type)                        
{                                                  
	if(type==0)                                   
	{                                              
		fseek(fp,sizeof(int)*(DIR_NUM+FILE_NUM+BLOCK_NUM+3)+sizeof(struct dir_node)*pos,SEEK_SET);
		fwrite(&dir[pos],sizeof(struct dir_node),1,fp);
	}
	else
	{
		fseek(fp,sizeof(int)*(DIR_NUM+FILE_NUM+BLOCK_NUM+3)+sizeof(struct dir_node)*DIR_NUM+sizeof(struct file_node)*pos,SEEK_SET);
		fwrite(&file[pos],sizeof(struct file_node),1,fp);
	}
}

/***************************************************************************************************************
//显式保存文件的核心函数   
****************************************************************************************************************/
void savefile(int file_id)                         
{
	if(al_fflag[file_id]%2!=0)                     //如果创建或删除，需要写回磁盘	
	{					
		write_bit(file_id,1);		
		al_fflag[file_id]=0;	
	}
	if(al_file[file_id]>0)                         //如果控制信息被修改，需要写回磁盘
	{	
		write_inode(file_id,1);	
		al_file[file_id]=0;
		for(int i=0;i<file[file_id].block_count;i++)		
		{			
			int temp=file[file_id].block[i];			
			if(al_bflag[temp]%2!=0)                //如果磁盘块被释放或被占用，需要写回磁盘			
			{				
				write_bit(temp,2);				
				al_bflag[temp]=0;
			}
		}
	}
}

void save_dir(int dir_id)                          //保存空目录函数
{
	if(al_dflag[dir_id]%2!=0)                      //如果删除或创建，需要写回磁盘	
	{		
		write_bit(dir_id,0);			
		al_dflag[dir_id]=0;	
	}
	if(al_dir[dir_id]>0)                           //如果控制信息被修改，需要写回磁盘		
	{
		write_inode(dir_id,0);		
		al_dir[dir_id]=0;
	}
}
void save(int dir_id)                              //保存一个目录及它下面的所有目录及文件
{                                                  //用了递归
	for(int i=0;i<dir[dir_id].dir_count;i++)
		save(dir[dir_id].child_dir[i]);
	for(i=0;i<dir[dir_id].file_count;i++)
		savefile(dir[dir_id].child_file[i]);
	save_dir(dir_id);
}
/***************************************************************************************************************
    //格式化，相当于重新创建文件系统
****************************************************************************************************************/
void format()                                      
{
	create_file_system();
	fp=fopen(file_system_name,"rb+");
	if(fp==NULL)
	{
		printf("Open file system error!\n");
		exit(1);
	}

	curr=0;	
	curr_dir=&dir[curr];                           //设置当前目录为根目录	
	strcpy(curr_path,curr_dir->dir_name);	
	strcat(curr_path,"/");
}
/***************************************************************************************************************
//打开文件系统   
****************************************************************************************************************/
void open_file_system()                                                 
{
	int flag=0;
	fp=fopen(file_system_name,"rb");               //以读方式打开，如果不存在，则创建文件系统
	if(fp==NULL)                            
	{
		create_file_system();
		flag=1;
	}
	fp=fopen(file_system_name,"rb+");              //以读写方式打开
	if(fp==NULL)
	{
		printf("Open file system error!\n");
		exit(1);
	}
	if(flag==0)                                    //如果该文件系统早就创建，则将其信息读入主存                          
	{
		fseek(fp,0,SEEK_SET);                      //读超级块信息
		fread(&used_dir,sizeof(int),1,fp);
		fread(&used_file,sizeof(int),1,fp);
		fread(&used_block,sizeof(int),1,fp);

		for(int i=0;i<DIR_NUM;i++)
			fread(&dir_flag[i],sizeof(int),1,fp);
		for(i=0;i<FILE_NUM;i++)
			fread(&file_flag[i],sizeof(int),1,fp);
		for(i=0;i<BLOCK_NUM;i++)
			fread(&block_flag[i],sizeof(int),1,fp);

		for(i=0;i<DIR_NUM;i++)                     //读目录及文件的控制信息
			if(dir_flag[i]==1)
			{
				fseek(fp,sizeof(int)*(DIR_NUM+FILE_NUM+BLOCK_NUM+3)+sizeof(struct dir_node)*i,SEEK_SET);			
				fread(&dir[i],sizeof(struct dir_node),1,fp);
			}
		for(i=0;i<FILE_NUM;i++)
			if(file_flag[i]==1)
			{
				fseek(fp,sizeof(int)*(DIR_NUM+FILE_NUM+BLOCK_NUM+3)+sizeof(struct dir_node)*DIR_NUM+sizeof(struct file_node)*i,SEEK_SET);					
				fread(&file[i],sizeof(struct file_node),1,fp);
			}
	}
 	fflush(fp);

	curr=0;
	curr_dir=&dir[curr];                           //设置当前目录为根目录
	strcpy(curr_path,curr_dir->dir_name);
	strcat(curr_path,"/");
}

/***************************************************************************************************************
//关闭文件系统，并保存相应信息，这是系统隐式保存文件及目录的方法
    
****************************************************************************************************************/
void close_file_system()                           
{                                               
	save(0);
	for(int i=0;i<DIR_NUM;i++)
		if(al_dflag[i]%2!=0)
			write_bit(i,0);
	for(i=0;i<FILE_NUM;i++)
		if(al_fflag[i]%2!=0)
			write_bit(i,1);
	for(i=0;i<BLOCK_NUM;i++)
		if(al_bflag[i]%2!=0)
			write_bit(i,2);

	fseek(fp,0,SEEK_SET);
	fwrite(&used_dir,sizeof(int),1,fp);
	fwrite(&used_file,sizeof(int),1,fp);
	fwrite(&used_block,sizeof(int),1,fp);

	fclose(fp);
}

/***************************************************************************************************************
打印命令及解释
****************************************************************************************************************/
void help()                               
{
	printf("Commands:                 Explanation:\n");
	printf("    0  exit:                 Exit!\n");
	printf("    1  format:                 Format the disk!\n");  
	printf("    2  mkf:                 Create a new file!\n");  
	printf("    3  mkd:                 Create a new directory!\n");  
	printf("    4  delf:                 Delete a file!\n");  
	printf("    5  deld:                 Delete a directory!\n");  
	printf("    6  cd:                 Change the current directory!\n");
	printf("    7  dir:                 Show the current files and directories!\n");
    printf("    8  tree:                 Show directory tree!\n");
	printf("    9  help:                 Print commands!\n");
	
}

/***************************************************************************************************************
命令接受及解析，转入相应函数运行   
****************************************************************************************************************/
void run()                               
{
	char *command[10]={"exit","dir","mkf","mkd","delf","deld","cd","format","help","tree"};
	char buf1[256];   /* 0    , 1  ,  2  ,  3  ,  4   ,  5   ,  6  ,  7   ,  8   ,     9  	*/					
	char buf2[2048];
	char buf3[128];
	char buf4[128];
	int key,num,index,del_pos,parent,p;
	char *s,flag='\0';
	cout<<"=============================================================================="<<endl;
	help();
	cout<<"=============================================================================="<<endl;
	cout<<"Input help to print commands!"<<endl;
	while(1)
	{
		strcpy(buf1,"");
		strcpy(buf2,"");
		strcpy(buf3,"");
		strcpy(buf4,"");
		p=0;
		printf("\n%s\n",curr_path);
		cin.getline(buf1,256,'\n');
		key=-1;
		for(int i=0;i<=10;i++)                     //命令匹配
			if(strncmp(buf1,command[i],(int)strlen(command[i]))==0)
			{
				key=i;
				break;
			}
		if(key!=-1)                                //参数分解
		{
			s=strchr(buf1,' ');
			if(s!=NULL)
			{
				index=(int)(s-buf1);
				while(buf1[index]==' ')
					index++;
				strcpy(buf3,buf1+index);
				s=strchr(buf3,' ');
				if(s!=NULL)
				{
					num=(int)(s-buf3);		
					buf3[num]='\0';
				}
				s=strrchr(buf1+index,' ');
				if(s!=NULL)
				{
					index=(int)(s-buf1);
					strcpy(buf4,buf1+index+1);
				}
			}
		}
		switch(key)
		{
		case -1:
			printf("The command you input not exist!\n");
			break;
		case 0:  //exit
			return;
		case 1:  //dir
			list();
			break;
		case 2:  //mkf
			if((int)strlen(buf3)==0)
			{			
				printf("please input the name of the file:\n");			
				cin.getline(buf3,128,'\n');			
			}
			if(create(buf3)!=-1)				
				printf("Succeed!");
			break;
		case 3:  //mkd
			if((int)strlen(buf3)==0)			
			{			
				printf("please input the name of the directory:\n");	
				cin.getline(buf3,128,'\n');			
			}
			if(md(buf3)!=-1)				
				printf("Succeed!");
			break;
		case 4: //delf
			if((int)strlen(buf3)==0)
			{			
				printf("please input the name of the file:\n");			
				cin.getline(buf3,128,'\n');			
			}
			if(delfile(buf3)!=-1)				
				printf("Succeed!");
			break;
		case 5: //deld
			if((int)strlen(buf3)==0)
			{
				printf("please input the name of the directory:\n");			
				cin.getline(buf3,128,'\n');
			}			
			parent=get_parent(buf3,p);
			if(parent==-1)
			{		
				printf("Path name error!");		
				break;	
			}
			if((del_pos=search(parent,buf3+p,0,index))==-1)
			{	
				printf("The directory to delete not exist in current directory!\n");
				break;
			}
			if(dir[del_pos].dir_count>0 || dir[del_pos].file_count>0)
			{
				printf("The directory is not empty!\nAre you sure to delete it?('Y' or 'N')");			
				cin.getline(&flag,32,'\n');			
				if(flag!='Y' && flag!='y')			
					break;
			}
			del_dir(parent,del_pos,index);
			printf("Succeed!");
			break;
		case 6:  //cd
			if((int)strlen(buf3)==0)
			{
				printf("please input the name of the diectory:\n");	
				cin.getline(buf3,128,'\n');
			}
			if(change_dir(buf3)!=-1)
				printf("Succeed!");	
			break;
		case 7:
			format();
			printf("Succeed!");
			break;
		case 8:
			help();
			break;
		case 9:
			show_tree();
			break;
		}
	}
}

void main()
{
	open_file_system();
	run();
	close_file_system();
}