unix文件系统模拟－操作系统课程设计

本周进行操作系统课程设计，在很多的题目中选了个unix文件系统模拟，主要就是操作结构与文件。

为了方便，文件系统结构如下：

Super block   --  Block bitmap  -- Inode bitmap  -- Inode table -- Block zone

其中：

Super block: 存储基本信息

Block bitmap:块分配情况

Inode bitmap:索引节点分配情况

Inode table: Indoe 节点存放区

Block zone:存放数据区

效果如下：

总的说来,做的还是挺简单的,只是实现了基本的功能.而块的分配没有怎么完成,linux系统中一般是通过多级索引的方式为inode分配块.

刚开始我的想法是:inode的块(512B)只写510B,留下2B用于记录下一块的块号,我觉得应该可行,但觉得繁,就没有写下去.所以就没有多余的

块分配操作.知识INode对应一个Block....,太懒了.还有一个缺点,文件指针移动太频繁了,而且都是绝对定位移动(好算,呵呵)

代码如下：

/*核心思想：一切皆是文件
如果是目录：Block中存储的是目录下文件和目录的fcb
如果是文件：Block中存储的是文件的内容
*/
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <malloc.h>
#include <signal.h>

#define BLOCKSIZE 512
#define BLOCKNUM  512
#define INODENUM  30
#define FILENAME "file.dat"

typedef struct{
	unsigned short blockSize;
	unsigned short blockNum;
	unsigned short inodeNum;
	unsigned short blockFree;
	unsigned short inodeFree;
}SuperBlock;

typedef struct{
	unsigned short inum;
	char fileName[10];
	unsigned short isDir;  // 0-file 1-dir
	unsigned short iparent;
	unsigned short length;    //if file->filesize  if dir->filenum
	unsigned short blockNum;
}Inode,*PtrInode;

//Fcb用于存储文件与 目录信息，主要用途：将一个目录下的所有文件(包括目录)写入到该目录对应的Block中
typedef struct {
    unsigned short inum;
    char fileName[10];
    unsigned short isDir;
}Fcb,*PtrFcb;


typedef struct{
	char userName[10];
	char passWord[10];
}User;


char blockBitmap[BLOCKNUM];
char inodeBitmap[INODENUM];

SuperBlock superBlock;
User curUser=(User){"root","root"};

unsigned short currentDir; //current inodenum
FILE *fp;
const unsigned short superBlockSize=sizeof(superBlock);
const unsigned short blockBitmapSize=sizeof(blockBitmap);
const unsigned short inodeBitmapSize=sizeof(inodeBitmap);
const unsigned short inodeSize=sizeof(Inode);
const unsigned short fcbSize=sizeof(Fcb);
char		*argv[5];
int argc;


void createFileSystem()
/*创建*/
{
	long len;
	PtrInode fileInode;
	if ((fp=fopen(FILENAME,"wb+"))==NULL)
	{
		printf("open file %s error...\n",FILENAME);
		exit(1);
	}

    //init bitmap
	for(len=0;len<BLOCKNUM;len++)
        blockBitmap[len]=0;

    for(len=0;len<INODENUM;len++)
        inodeBitmap[len]=0;

     //memset

	for (len=0;len<(superBlockSize+blockBitmapSize+inodeBitmapSize+inodeSize*INODENUM+BLOCKSIZE*BLOCKNUM);len++)
	{
		fputc(0,fp);
	}
	rewind(fp);

	//init superBlock
	superBlock.blockNum=BLOCKNUM;
	superBlock.blockSize=BLOCKSIZE;
	superBlock.inodeNum=INODENUM;
	superBlock.blockFree=BLOCKNUM-1;
	superBlock.inodeFree=INODENUM-1;

	fwrite(&superBlock,superBlockSize,1,fp);

	//create root
	fileInode=(PtrInode)malloc(inodeSize);
	fileInode->inum=0;
	strcpy(fileInode->fileName,"/");
	fileInode->isDir=1;
	fileInode->iparent=0;
	fileInode->length=0;
	fileInode->blockNum=0;

	//write / info to file
	inodeBitmap[0]=1;
	blockBitmap[0]=1;
	fseek(fp,superBlockSize,SEEK_SET);
	fwrite(blockBitmap,blockBitmapSize,1,fp);
	fseek(fp,superBlockSize+blockBitmapSize,SEEK_SET);
	fwrite(inodeBitmap,inodeBitmapSize,1,fp);
	fseek(fp,superBlockSize+blockBitmapSize+inodeBitmapSize,SEEK_SET);
	fwrite(fileInode,inodeSize,1,fp);
	fflush(fp);

	//point to currentDir
	currentDir=0;

}

void openFileSystem()
/*如果FILENAME可读，则代表之前已有信息，并读取相应数据    如果不可读，则创建文件系统 */
{

	if((fp=fopen(FILENAME,"rb"))==NULL)
	{
		createFileSystem();
	}
	else
	{
	    if ((fp=fopen(FILENAME,"rb+"))==NULL)
        {
            printf("open file %s error...\n",FILENAME);
            exit(1);
        }
	    rewind(fp);
        //read superBlock from file
        fread(&superBlock,superBlockSize,1,fp);

        //read bitmap from file
        fread(blockBitmap,blockBitmapSize,1,fp);
        fread(inodeBitmap,inodeBitmapSize,1,fp);

        //init current dir
        currentDir=0;

	}

}


void createFile(char *name,int flag) //flag=0 ->create file   =1 ->directory
{
	int i,nowBlockNum,nowInodeNUm;
	PtrInode fileInode=(PtrInode)malloc(inodeSize);
	PtrInode parentInode=(PtrInode)malloc(inodeSize);
	PtrFcb fcb=(PtrFcb)malloc(fcbSize);

	//the available blockNumber
	for(i=0;i<BLOCKNUM;i++)
	{
		if(blockBitmap[i]==0)
		{
			nowBlockNum=i;
			break;
		}

	}

	//the available inodeNumber
	for(i=0;i<INODENUM;i++)
		{
			if(inodeBitmap[i]==0)
			{
				nowInodeNUm=i;
				break;
			}

		}

	//init fileINode struct
	fileInode->blockNum=nowBlockNum;
	strcpy(fileInode->fileName,name);
	fileInode->inum=nowInodeNUm;
	fileInode->iparent=currentDir;
	if(flag==0)
	{
		fileInode->isDir=0;
	}
	else
	{
		fileInode->isDir=1;
	}
	fileInode->length=0;

	//write fileInfo to file
	fseek(fp,superBlockSize+blockBitmapSize+inodeBitmapSize+inodeSize*nowInodeNUm,SEEK_SET);
	fwrite(fileInode,inodeSize,1,fp);

	//update superBlock and bitmap
	superBlock.blockFree-=1;
	superBlock.inodeFree-=1;
	blockBitmap[nowBlockNum]=1;
	inodeBitmap[nowInodeNUm]=1;

	//init fcb info
	strcpy(fcb->fileName,fileInode->fileName);
	fcb->inum=fileInode->inum;
	fcb->isDir=fileInode->isDir;

	//update to file ...

	//update parent dir block info
	fseek(fp,superBlockSize+blockBitmapSize+inodeBitmapSize+currentDir*inodeSize,SEEK_SET);
	fread(parentInode,inodeSize,1,fp);
	fseek(fp,superBlockSize+blockBitmapSize+inodeBitmapSize+INODENUM*inodeSize+parentInode->blockNum*BLOCKSIZE+parentInode->length*fcbSize,SEEK_SET);
	fwrite(fcb,fcbSize,1,fp);

	//update parent dir inode info
	parentInode->length+=1;
	fseek(fp,superBlockSize+blockBitmapSize+inodeBitmapSize+currentDir*inodeSize,SEEK_SET);
	fwrite(parentInode,inodeSize,1,fp);

	// free resource
	free(fileInode);
	free(parentInode);
	free(fcb);
}



void list()
{
	int i;
	PtrFcb fcb=(PtrFcb)malloc(fcbSize);
	PtrInode parentInode=(PtrInode)malloc(inodeSize);

	//read parent inode info from file
	fseek(fp,superBlockSize+blockBitmapSize+inodeBitmapSize+currentDir*inodeSize,SEEK_SET);
	fread(parentInode,inodeSize,1,fp);

	//point to parent dir block
	fseek(fp,superBlockSize+blockBitmapSize+inodeBitmapSize+inodeSize*INODENUM+parentInode->blockNum*BLOCKSIZE,SEEK_SET);

	//list info
	for(i=0;i<parentInode->length;i++)
	{
		fread(fcb,fcbSize,1,fp);
		printf("Filename: %-10s",fcb->fileName);
		printf("Inode number: %-2d    ",fcb->inum);
		if(fcb->isDir==1)
		{
		printf("Directory\n");
		}
		else
		{
			printf("Regular file\n");
		}
	}

	//free resource
	free(fcb);
	free(parentInode);
}


int findInodeNum(char *name,int flag)  //flag=0 ->find file flag=1 -> find dir
{
	int i,fileInodeNum;
	PtrInode parentInode=(PtrInode)malloc(inodeSize);
	PtrFcb fcb=(PtrFcb)malloc(fcbSize);

	//read current inode info from file
	fseek(fp,superBlockSize+blockBitmapSize+inodeBitmapSize+currentDir*inodeSize,SEEK_SET);
	fread(parentInode,inodeSize,1,fp);

	//read the fcb in the current dir block
	fseek(fp,superBlockSize+blockBitmapSize+inodeBitmapSize+inodeSize*INODENUM+parentInode->blockNum*BLOCKSIZE,SEEK_SET);

	for(i=0;i<parentInode->length;i++)
	{
		fread(fcb,fcbSize,1,fp);
		if(flag==0)
		{
			if((fcb->isDir==0)&&(strcmp(name,fcb->fileName)==0))
					{
						fileInodeNum=fcb->inum;
						break;
					}

		}
		else
		{
			if((fcb->isDir==1)&&(strcmp(name,fcb->fileName)==0))
					{
						fileInodeNum=fcb->inum;
						break;
					}

		}
	}

	if(i==parentInode->length)
			fileInodeNum=-1;

	free(fcb);
	free(parentInode);
	return fileInodeNum;
}

void cd(char *name)
{
	int fileInodeNum;
	PtrInode fileInode=(PtrInode)malloc(inodeSize);
	if(strcmp(name,"..")!=0)
	{
		fileInodeNum=findInodeNum(name,1);
		if(fileInodeNum==-1)
			printf("This is no %s directory...\n",name);
		else
		{
			currentDir=fileInodeNum;
		}
	}
	else
	{
		fseek(fp,superBlockSize+blockBitmapSize+inodeBitmapSize+currentDir*inodeSize,SEEK_SET);
		fread(fileInode,inodeSize,1,fp);
		currentDir=fileInode->iparent;

	}
	free(fileInode);
}

void cdParent()
{
	PtrInode fileInode=(PtrInode)malloc(inodeSize);
	fseek(fp,superBlockSize+blockBitmapSize+inodeBitmapSize+currentDir*inodeSize,SEEK_SET);
	fread(fileInode,inodeSize,1,fp);
	currentDir=fileInode->iparent;

	free(fileInode);
}

void write(char *name)
{
	int fileInodeNum,i=0;
	char c;
	PtrInode fileInode=(PtrInode)malloc(inodeSize);
	if((fileInodeNum=findInodeNum(name,1))!=-1)
	{
		printf("This is a directory,not a file...\n");
		return;
	}

	fileInodeNum=findInodeNum(name,0);
	if(fileInodeNum==-1)
		printf("This is no %s file...\n",name);
	else
	{
		//get inode->blocknum
		fseek(fp,superBlockSize+blockBitmapSize+inodeBitmapSize+fileInodeNum*inodeSize,SEEK_SET);
		fread(fileInode,inodeSize,1,fp);
		//point to the block site
		fseek(fp,superBlockSize+blockBitmapSize+inodeBitmapSize+INODENUM*inodeSize+fileInode->blockNum*BLOCKSIZE,SEEK_SET);
		printf("please input file content(stop by #):\n");
		while((c=getchar())!='#')
		{
			fputc(c,fp);
			i++;
		}

		//update inode->length
		fseek(fp,superBlockSize+blockBitmapSize+inodeBitmapSize+fileInodeNum*inodeSize,SEEK_SET);
		fread(fileInode,inodeSize,1,fp);
		fileInode->length=i-1;
		fseek(fp,-inodeSize,SEEK_CUR);
		fwrite(fileInode,inodeSize,1,fp);
	}

	free(fileInode);

}

void read(char *name)
{
	int fileInodeNum;
	char c;
	PtrInode fileInode=(PtrInode)malloc(inodeSize);
	if((fileInodeNum=findInodeNum(name,1))!=-1)
	{
			printf("This is a directory,not a file...\n");
			return;
	}
	fileInodeNum=findInodeNum(name,0);
	if(fileInodeNum==-1)
		printf("This is no %s file...\n",name);
	else
	{
		//get inode->blocknum
		fseek(fp,superBlockSize+blockBitmapSize+inodeBitmapSize+fileInodeNum*inodeSize,SEEK_SET);
		fread(fileInode,inodeSize,1,fp);
		//point to the block site
		fseek(fp,superBlockSize+blockBitmapSize+inodeBitmapSize+INODENUM*inodeSize+fileInode->blockNum*BLOCKSIZE,SEEK_SET);

		//read content
		if(fileInode->length!=0)
		{
			while((c=fgetc(fp))!=EOF)
			{
				putchar(c);
			}
			printf("\n");
		}

	}

	free(fileInode);
}


void delete(char *name) 
/*delete 一个文件，需要修改SuperBlock,Blockbitmap,Inodebitmap,并更新父节点长度，删除父节点Block中存储的该文件fcb*/ 
{
	int fileInodeNum,i;
	PtrInode fileInode=(PtrInode)malloc(inodeSize);
	PtrInode parentInode=(PtrInode)malloc(inodeSize);
	Fcb fcb[20];
	if(((fileInodeNum=findInodeNum(name,0))==-1)&&((fileInodeNum=findInodeNum(name,1))==-1))
	{
		printf("This is no %s...\n",name);
	}
	else
	{
		if((fileInodeNum=findInodeNum(name,0))==-1)
		{
			fileInodeNum=findInodeNum(name,1);
		}

		fseek(fp,superBlockSize+blockBitmapSize+inodeBitmapSize+fileInodeNum*inodeSize,SEEK_SET);
		fread(fileInode,inodeSize,1,fp);

		fseek(fp,superBlockSize+blockBitmapSize+inodeBitmapSize+fileInode->iparent*inodeSize,SEEK_SET);
		fread(parentInode,inodeSize,1,fp);


		//update parent info
		fseek(fp,superBlockSize+blockBitmapSize+inodeBitmapSize+INODENUM*inodeSize+parentInode->blockNum*BLOCKSIZE,SEEK_SET);
		for(i=0;i<parentInode->length;i++)
		{
			fread(&fcb[i],fcbSize,1,fp);
				//fcb[i]=tmp;
		}

		fseek(fp,superBlockSize+blockBitmapSize+inodeBitmapSize+INODENUM*inodeSize+parentInode->blockNum*BLOCKSIZE,SEEK_SET);
		for(i=0;i<BLOCKSIZE;i++)
				fputc(0,fp);

		fseek(fp,superBlockSize+blockBitmapSize+inodeBitmapSize+INODENUM*inodeSize+parentInode->blockNum*BLOCKSIZE,SEEK_SET);
		for(i=0;i<parentInode->length;i++)
		{
			if((strcmp(fcb[i].fileName,name))!=0)
			{
					fwrite(&fcb[i],fcbSize,1,fp);
			}
		}

		parentInode->length-=1;
		fseek(fp,superBlockSize+blockBitmapSize+inodeBitmapSize+fileInode->iparent*inodeSize,SEEK_SET);
		fwrite(parentInode,inodeSize,1,fp);
		//update bitmap
		inodeBitmap[fileInodeNum]=0;
		blockBitmap[fileInode->blockNum]=0;

		//update superblock
		superBlock.blockFree+=1;
		superBlock.inodeFree+=1;
	}

	free(fileInode);
	free(parentInode);

}

void updateResource()
{
	rewind(fp);
	fwrite(&superBlock,superBlockSize,1,fp);
	fwrite(blockBitmap,blockBitmapSize,1,fp);
	fwrite(inodeBitmap,inodeBitmapSize,1,fp);
	fclose(fp);
}

void pathSet()
{
	PtrInode curInode=(PtrInode)malloc(inodeSize);
	fseek(fp,superBlockSize+blockBitmapSize+inodeBitmapSize+currentDir*inodeSize,SEEK_SET);
	fread(curInode,inodeSize,1,fp);
	printf("%s@localhost:%s#",curUser.userName,curInode->fileName);
	free(curInode);
}

void systemInfo()
{
	printf("Sum of block number:%d\n",superBlock.blockNum);
	printf("Each block size:%d\n",superBlock.blockSize);
	printf("Free of block number:%d\n",superBlock.blockFree);
	printf("Sum of inode number:%d\n",superBlock.inodeNum);
	printf("Free of inode number:%d\n",superBlock.inodeFree);
}

void help()
{
	printf("command: \n\
	help   ---  show help menu \n\
	sysinfo  --- show system base information \n\
	cls  ---  clear the screen \n\
	cd     ---  change directory \n\
	mkdir  ---  make directory   \n\
	touch  ---  create a new file \n\
	cat   ---  read a file \n\
	write  ---  write something to a file \n\
	logout ---  exit user \n\
	rm     ---  delete a directory or a file \n\
	exit   ---  exit this system\n");
}

int analyse(char *str)
{
	int  i;
	char temp[20];
	char *ptr_char;
	char *syscmd[]={"help","ls","cd","mkdir","touch","cat","write","rm","logout","exit","sysinfo","cls"};
	argc = 0;
	for(i = 0, ptr_char = str; *ptr_char != '\0'; ptr_char++)
	{
		if(*ptr_char != ' ')
		{
			while(*ptr_char != ' ' && (*ptr_char != '\0'))
				temp[i++] = *ptr_char++;
			argv[argc] = (char *)malloc(i+1);
			strncpy(argv[argc], temp, i);
			argv[argc][i] = '\0';
			argc++;
			i = 0;
			if(*ptr_char == '\0')
				break;
		}
	}
	if(argc != 0)
	{
		for(i = 0; (i < 12) && strcmp(argv[0], syscmd[i]); i++);
			return i;
	}
	else
		return 12;
	return 0;
}

void login()
{
	char userName[10];
	char passWord[10];
	while(1)
	{
		printf("login:");
		gets(userName);
        system("stty -echo");
		printf("passwd:");
		gets(passWord);
		system("stty echo");
		printf("\n");
		if(strcmp(userName,curUser.userName)==0&&strcmp(passWord,curUser.passWord)==0)
			break;
	}
}

void stopHandle(int sig)
{
    printf("\nPlease wait...,update resource\n");
    updateResource();
    exit(0);
}

void command(void)
{
	char cmd[20];
	do
	{
		pathSet();
		gets(cmd);
		switch(analyse(cmd))
		{
			case 0:
				help();
				break;
			case 1:
				list();
				break;
			case 2:
				cd(argv[1]);
				break;
			case 3:
				createFile(argv[1],1);
				break;
			case 4:
				createFile(argv[1],0);
				break;
			case 5:
				read(argv[1]);
				break;
			case 6:
				write(argv[1]);
				break;
			case 7:
				delete(argv[1]);
				break;
			case 8:
				updateResource();
				login();
				openFileSystem();
                command();
				break;
			case 9:
				updateResource();
				exit(0);
				break;
			case 10:
				systemInfo();
				break;
            case 11:
                system("clear");
				break;
			default:
				break;
		}
	}while(1);
}

int main(int argc,char **argv){
    signal(SIGINT,stopHandle);
	login();
	openFileSystem();
	command();
	return 0;
}