OS Experiment 7 [document management]

Catalog

One 、 The experiment purpose

Two 、 Experimental content

3、 ... and 、 The experimental requirements

Four 、 Design principle and related algorithms

5、 ... and 、 Result analysis  

1. Compile the file test08.cpp

2. format： Format command

3. mkdir hello： establish hello subdirectories

4. ls hello： Show hello Information in the directory

5. cd hello： Get into hello Catalog

6. create world 100： Create a new file world

7. cp world hello： Copy file wold File for hello

8. rename hello world2： Rename file hello by world2

9. rm world： Delete world file

10. rmdir hello： Delete hello Catalog

11. exit： Exit the system and save the message

6、 ... and 、 Source code  

---

One 、 The experiment purpose

1、 Explore 、 Understand and master FAT The organizational structure of the file system 、 Design principle and programming design gist .

2、 Through the experiment , master MSDOS Implementation method of file directory management in file system .

Two 、 Experimental content

1、 Design and implement a directory list for implementation （ similar DOS Under the DIR Order or Linux Of Shell command ls） Function of .

2、 Design and implement a function for renaming files .

3、 Design and implement a function for file deletion .

4*、 Design and implement the creation of new directories 、 A function that copies an existing file to a new file .

The prototypes of these functions are as follows ：

int fd_ls();

int fd_rename(char *oldfilename,char *newfilename);

int fd_rm(char *name);

int fd_mkdir(char *name);

int fd_cp(char *source, char *destination);

3、 ... and 、 The experimental requirements

This experiment MSDOS Format on floppy disk . To implement these functions, you need a function that prepares the physical disk （ The letter Call the initialization code of the disk driver and other initialization codes selected to determine the disk geometry ）： int fd_load(char driveLetter); Renaming and deleting files , You need to find the file , File deletion also involves traversal FAT Link in , Set up FAT And mark it as unused , Update catalog entries . In the case of deletion , Pay attention to file hiding 、 Read only and system properties . Any file with this attribute cannot be deleted .

Besides , Mission 4 We still need fd_open()、fd_close()、fd_read()、fd_write() Function to write byte stream .

Four 、 Design principle and related algorithms

Want to complete the operating system algorithm , First of all, we should understand the terminology related to the operating system . Clarify the flow and purpose requirements of each algorithm . In order to simulate the process of related algorithms .

In general , Operating system , File management provides the following functions ：

① Unified management of file storage space ( That is, external deposit ), Implement the allocation and recycling of storage space .
② Determine the storage location and storage form of document information .
③ Realize the mapping of files from namespace to external memory address space , That is to realize the access of files by name .
④ Effectively realize various control operations on documents ( Such as the establishment of 、 revoke 、 open 、 Close files, etc ) And access operations ( As read 、 Write 、 modify 、 Copy 、 Dump, etc )

In fact, it is to manage files .

This experiment defines the following data structure for the file ：

class file:
    def __init__(self, uid, fid, name, status):
        self.uid = uid
        self.fid = fid
        self.name = name
        self.status = status

Defines the of the file id identification , file name , Status and so on .

5、 ... and 、 Result analysis  

1. Compile the file test08.cpp

g++ test08.cpp -o test08

2. format： Format command

3. mkdir hello： establish hello subdirectories

4. ls hello： Show hello Information in the directory

5. cd hello： Get into hello Catalog

6. create world 100： Create a new file world

7. cp world hello： Copy file wold File for hello

8. rename hello world2： Rename file hello by world2

9. rm world： Delete world file

10. rmdir hello： Delete hello Catalog

11. exit： Exit the system and save the message

6、 ... and 、 Source code  

create a file test08.cpp

vim test08.cpp
g++ test08.cpp -o test08

#include <iostream>
#include <stdio.h>
#include <stdlib.h>
#include <string>
#include <string.h>
#include <bitset>

using namespace std;
const int BLOCKNUM_SIZE=2;					// Disk block number size 
const int BLOCK_SIZE=1024;				    // The size of a disk block 
const int BLOCK_NUM=10001;				    // Number of disks 
const int DISK_SIZE=1024*1000*10;			// Disk size 
const int LIST_SIZE=32;						// Directory entry size 
const int MAP_SIZE=10001;						//MAP  length 
const int FATNUM=125;						//FAT Number of disks   The first block is useless 
const int FATLIST=512;					// Each coil opening FAT Number of records 
const int DATABEG=128;					// Data item start FAT Number 

struct FCB{
    char fname[8];						// file name 
    char exname[3];						// Extension 
    short  fnum;						// First block No 
    int length;							// file size ,   Directory, the file size is ;
};

struct fatid{
    short id[FATNUM*FATLIST];   //FAT  size 512 A record   A piece of 
}*FAT;

struct map{
    bitset<MAP_SIZE> maplist;
}*MAP;

struct DIR{
    struct FCB list[LIST_SIZE+1];
}*filedir;

int currentid=128;                  // At present FAT Number 
int currentdir=128;                 // Current directory block number initialization is +1   Since unit is not used 
char *file;                          // The first address of the disk 
char *FilePath="myfat";              //window File storage address 
FILE *fp;                           //window  File address 
string CURRENT="root\\";				// current path 
char  cmd[30];						// Input instruction 
char command[16];



/*
* Format the file storage 
* Create the root directory 
*
*/
void init(struct fatid *FAT){
    int i,j;
    for(i=1;i<FATNUM*FATLIST;i++)			// Block   Don't use 
    {
        if(i>DATABEG)
            FAT->id[i]=0;
        else
            FAT->id[i]=-1;
    }
}
void format(){
    bool i;
    FAT=(struct fatid *)(file+BLOCK_SIZE);                         // At present FAT Address 
    MAP=(struct map *)(file+(FATNUM+1)*BLOCK_SIZE);       // Initialization bit diagram 
    init(FAT);
    FAT->id[0]=9872;
    filedir=(struct DIR *)(file+(FATNUM+1+2)*BLOCK_SIZE);		  // Current directory pointer address 
    FAT->id[128]=-1;
    FAT->id[0]=9872-1;
    strcpy(filedir->list[0].fname,".");
    strcpy(filedir->list[0].exname,"dir");
    filedir->list[0].fnum=currentdir;
    filedir->list[0].length=0;
    strcpy(filedir->list[1].fname,"..");
    strcpy(filedir->list[1].exname,"dir");
    filedir->list[1].fnum=currentdir;
    filedir->list[1].length=0;
    fp=fopen(FilePath,"w+");
    fwrite(file,sizeof(char),DISK_SIZE,fp);
    fclose(fp);
    printf(" Initialization is complete , Now you can operate !\n\n");
}

/*
* Create subdirectories 
*/
int mkdir(char *str)
{
    int i,j;
    int blockid;			// About to create FAT Number 
    int blockdir;			// Number of directory block to be created 
    int listnum;			// Number in the catalog block 

    struct fatid *flagid;
    struct DIR *dir;        // Current directory pointer 
    struct map *MAP;
    struct fatid *FAT;

    if(strcmp(str,"")==0)
    {
        printf(" Directory name cannot be empty \n");
        return 0;
    }

    dir=(struct DIR *)(file+(currentdir)*BLOCK_SIZE);
    MAP=(struct map *)(file+(FATNUM+1)*BLOCK_SIZE);
    FAT=(struct fatid *)(file+BLOCK_SIZE);

    for(i=DATABEG+1;i<BLOCK_NUM;i++)   // from 128 Block data block   The actual block starts searching 
        {
        if(MAP->maplist[i]==0)
            break;

        }

    if(i>BLOCK_NUM)
    {
        printf(" Out of memory \n");
        return 0;
    }

    MAP->maplist[i]=1;				//map  Set and use 


    dir=(struct DIR *)(file+(currentdir)*BLOCK_SIZE);


    for(i=2;i<LIST_SIZE;i++)
    {
        if(strcmp(dir->list[i].fname,str)==0)
        {
            printf(" There is a folder with the same name under the directory \n");
            return 0;
        }
    }
    for(i=2;i<LIST_SIZE;i++)
    {

        if(strcmp(dir->list[i].fname,"")==0)			// There are empty directory blocks and no duplicate names , The first version is put together with the above loop , There is a case where the previously created directory is deleted , Directly covered by the same name 
            break;
        if(i>LIST_SIZE)
        {
            printf(" Out of memory \n");
            return 0;
        }
    }
    flagid=(struct fatid *)(file+BLOCK_SIZE);	//fat  First address 

    for(j=DATABEG+1;j<BLOCK_NUM;j++)
    {
        if(flagid->id[j]==0)
        {
            blockdir=j;
            break;
        }
    }

    strcpy(dir->list[i].fname,str);
    dir->list[i].fnum=blockdir;
    strcpy(dir->list[i].exname,"dir");
    dir->list[i].length=0;


    dir=(struct DIR *)(file+blockdir*BLOCK_SIZE);   // Create a root directory for the new directory entry 
    strcpy(dir->list[0].fname,".");
    strcpy(dir->list[0].exname,"dir");
    dir->list[0].fnum=blockdir;
    dir->list[0].length=0;

    strcpy(dir->list[1].fname,"..");
    strcpy(dir->list[1].exname,"dir");
    dir->list[1].fnum=currentdir;
    dir->list[1].length=0;

    flagid->id[j]=-1;                 // modify FAT   Directory tail 
    FAT->id[0]=FAT->id[0]-1;

    printf(" The directory has been successfully created %s \n",str);

    return 0;
}

/*
* Show directory 
*/
int listshow()
{
    int i,sumfile,sumdir,fl[100],dr[100];//fl  Is the number of the document ,dr Is the number of the directory 
    sumfile=sumdir=0;

    struct DIR *dir;
    struct fatid *FAT;

    dir=(struct DIR *)(file+currentdir*BLOCK_SIZE);

    for(i=0;i<LIST_SIZE;i++)
    {
        if(dir->list[i].length==0&&(strcmp(dir->list[i].fname,"")!=0)&&(dir->list[i].fnum!=0))			// For directory 
            {
            dr[sumdir]=i;
            sumdir++;

            }
        if(dir->list[i].length!=0&&strcmp(dir->list[i].fname,"")!=0)			// For directory 
            {
            fl[sumfile]=i;
            sumfile++;

            }


    }

    for(i=0;i<sumdir;i++)
        printf("   %s        Folder \n",dir->list[dr[i]].fname);

    for(i=0;i<sumfile;i++)
        printf("   %s       %s file \n",dir->list[fl[i]].fname,dir->list[fl[i]].exname);

    printf("\n");

    printf("\n Under this directory, there are %d  File , %d  A folder \n\n",sumfile,sumdir-2);
    return 0;
}

/*
* delete a sub dir 
*/
int rmdir(char *str)
{
    int  i;
    int blockid;
    int flag=0;
    //FAT Number 
    int blocknum;				// Directory block 

    struct fatid *FAT;
    struct DIR *dir;
    struct DIR *flagdir;		// Mark the directory block 


    char c='a';			   // Do user interaction 
    int m=2;				// Search for the directory items to be deleted from the third subdirectory item 

    FAT=(struct fatid *)(file+BLOCK_SIZE);
    dir=(struct DIR *)(file+currentdir*BLOCK_SIZE);			// Current directory pointer 
    MAP=(struct map *)(file+(FATNUM+1)*BLOCK_SIZE);


    for(i=2;i<LIST_SIZE;i++)
    {
        if(strcmp(dir->list[i].fname,str)==0)		// Find the subdirectory to delete 
            {
            break;
            }
    }

    if(i>LIST_SIZE)
    {
        printf(" The folder does not exist %s",str);
        return 0;
    }


    while(1)
    {
        printf(" Are you sure ？（Y/N）");
        cin>>c;
        if((c=='y'||c=='Y')||(c=='n'||c=='N'))
            break;

    }

    if(c=='n'||c=='N')
        return 0;

    blocknum=dir->list[i].fnum;

    flagdir=(struct DIR *)(file+blocknum*BLOCK_SIZE);

    while(m!=LIST_SIZE)
    {
        if(strcmp(flagdir->list[m].fname,"")!=0)
        {
            printf(" There are sub files or sub directories under this directory , The directory cannot be deleted ");
        }
        m++;
    }

    strcpy(dir->list[i].fname,"");		// Parent directory DIR
    strcpy(dir->list[i].exname,"");
    dir->list[i].fnum=0;


    strcpy(flagdir->list[0].fname,"");			// To delete a directory DIR
    strcpy(flagdir->list[0].exname,"");
    flagdir->list[0].fnum=0;

    strcpy(flagdir->list[1].fname,"");
    strcpy(flagdir->list[1].exname,"");
    flagdir->list[0].fnum=0;

    MAP->maplist[blocknum]=0;
    FAT->id[blocknum]=0;
    FAT->id[0]=FAT->id[0]+1;

    return 0;
}

/*
* Change the current directory (cd command )
*/
int changedir(char *str)
{
    int i,j;
    int blocknum;			// Current directory location 
    int flagnum;			//temp Directory location of 
    struct DIR * flagdir,*dir;
    struct fatid * FAT;
    string strflag;     // To change the currently displayed code 


    dir=(struct DIR *)(file+currentdir*BLOCK_SIZE);

    if(strcmp("..",str)==0)					// Determine whether it is an upper level directory 
        {
        blocknum=currentdir;
        if(dir->list[0].fnum==dir->list[1].fnum)	// Characteristics of the root directory 
            {
            return 1;
            }

        currentdir=dir->list[1].fnum;							// Change the current directory pointer 

        flagdir=(struct DIR *)(file+currentdir*BLOCK_SIZE);		// Go to the upper directory address 

        for(int j=0;j<LIST_SIZE;j++)
        {
            if(flagdir->list[j].fnum==blocknum)
            {
                strflag=flagdir->list[j].fname;
                break;

            }
        }
        CURRENT=CURRENT.substr(0,(CURRENT.length()-strflag.length())-1);
        return 1;
        }

    for(i=2;i<LIST_SIZE;i++)									// subdirectories 
        {
        if(strcmp(dir->list[i].fname,str)==0&&strcmp(dir->list[i].exname,"dir")==0)
        {
            currentdir=dir->list[i].fnum;
            break;
        }
        }


    if(i>LIST_SIZE)
    {
        printf(" The specified directory could not be found %s\n",str);
        return 0;
    }

    CURRENT=CURRENT+str+"\\";
    return 1;
}

/*
* create a file 
*/
int create(char *str,int length)
{
    //getfilename
    int i,j,l,t,k;
    int blockdir;
    int fid;		//FAT The first block number of 
    int flag;		// First block judgment of file 
    char name[8]={0};	// File name 
    char exname[3]={0};	// File extension 
    int templength;      	//temp file length 

    struct fatid * FAT;
    struct DIR *dir;
    struct map *MAP;

    dir=(struct DIR *)(file+(currentdir)*BLOCK_SIZE);
    MAP=(struct map *)(file+(FATNUM+1)*BLOCK_SIZE);
    FAT=(struct fatid *)(file+BLOCK_SIZE);
    templength=length;

    l=strlen(str);
    // Take file name 
    for(i=0;i<l;i++)
    {

        name[i]=str[i];
        if(str[i+1]=='.')
            break;
    }

    if(i>=8)
    {
        printf(" The file name is too long \n");
        return 0;
    }

    // De extension 
    j=0;
    i++;
    i++;// Remove points 
    k=l-i;
    for(j=0;j<k;j++)
    {

        if(str[i]=='\0')
            break;
        exname[j]=str[i];
        i++;
    }
    if(strcmp(name,"0")==0)
    {
        printf(" File name cannot be empty \n");
        return 0;
    }

    if(length>FAT->id[0])
    {
        printf(" File exceeds disk space \n");
        return 0;
    }


    for(i=2;i<LIST_SIZE;i++)
    {
        if(strcmp(dir->list[i].fname,name)==0&&strcmp(dir->list[i].exname,exname)==0)
        {
            printf(" Under this folder , There is already a file with the same name ");
            return 0;
        }
        if(strcmp(dir->list[i].fname,"")==0)
        {
            break;
        }

    }
    if(i>LIST_SIZE)
    {
        printf(" Out of memory \n");
        return 0;
    }
    strcpy(dir->list[i].fname,name);
    strcpy(dir->list[i].exname,exname);
    dir->list[i].length=length;

    flag=1;
    j=DATABEG+1;

    while(1){// Keep cycling 
        if(MAP->maplist[j]!=1)
        {
            if(!templength--)	// When length All assigned until 
                break;
            // The address of the previous block 
            if(flag)		// The first allocation is the first address of 
                {
                dir->list[i].fnum=j;		// Give the first block of the file 

                }
            MAP->maplist[j]=1;				//MAP Reduce 
            if(!flag)
            {
                FAT->id[t]=j;
                FAT->id[0]=FAT->id[0]-1;
            }
            t=j;
            flag=0;
        }
        j++;
    }
    FAT->id[t]=-1;
    FAT->id[0]=FAT->id[0]-1;
    return 1;
}

/**
 Copy file 
*/
int cp(char *str,char *newname)
{
    int i,j,k,l,length;
    char name[8]={0};	// File name 
    char exname[3]={0};	// File extension 
    struct DIR *dir;
    l=strlen(str);
    // Take file name 
    for(i=0;i<l;i++)
    {
        name[i]=str[i];
        if(str[i+1]=='.')
            break;
    }
    // De extension 
    j=0;
    i++;
    i++;// Remove points 
    k=l-i;
    for(j=0;j<k;j++)
    {

        if(str[i]=='\0')
            break;
        exname[j]=str[i];
        i++;
    }
    if(strcmp(newname,"")==0)
    {
        printf(" File name cannot be empty \n");
        return 0;
    }
    dir=(struct DIR *)(file+currentdir*BLOCK_SIZE);

    for(i=2;i<LIST_SIZE;i++)									// Sub file 
        {
        if(strcmp(dir->list[i].fname,name)==0&&strcmp(dir->list[i].exname,exname)==0)
            break;

        }
    if(i>LIST_SIZE)
    {
        printf(" The specified file could not be found %s\n",str);
        return 0;
    }
    length=dir->list[i].length ;
    create(newname,length);
}

/*
* Delete file 
*/
int delfile(char *str)
{
    int i,j,l,k;
    int blocknum;       // First block address to delete 
    int temp;
    char name[8]={0};	// File name 
    char exname[3]={0};	// File extension 
    char c='a';

    struct DIR *dir;
    struct fatid *FAT;
    struct map *MAP;

    l=strlen(str);
    // Take file name 
    for(i=0;i<l;i++)
    {

        name[i]=str[i];
        if(str[i+1]=='.')
            break;
    }


    // De extension 
    j=0;
    i++;
    i++;// Remove points 
    k=l-i;
    for(j=0;j<k;j++)
    {

        if(str[i]=='\0')
            break;
        exname[j]=str[i];
        i++;
    }


    if(strcmp(str,"")==0)
    {
        printf(" File name cannot be empty \n");
        return 0;
    }

    dir=(struct DIR *)(file+(currentdir)*BLOCK_SIZE);
    MAP=(struct map *)(file+(FATNUM+1)*BLOCK_SIZE);
    FAT=(struct fatid *)(file+BLOCK_SIZE);

    for(i=2;i<LIST_SIZE;i++)
    {
        if((strcmp(dir->list[i].fname,name)==0)&&(strcmp(dir->list[i].exname,exname)==0))
            break;

    }
    if(i>LIST_SIZE)
    {
        printf(" Can't find %s  file \n",str);
        return 0;
    }

    if(c=='n'||c=='N')
        return 0;

    blocknum=dir->list[i].fnum;
    dir->list[i].fnum=0;				// Restore the catalog entries 
    strcpy(dir->list[i].exname,"");
    strcpy(dir->list[i].fname,"");
    dir->list[i].length=0;


    // Handle FAT AND MAP  surface 

    while(FAT->id[blocknum]!=-1)
    {
        temp=FAT->id[blocknum];;
        FAT->id[blocknum]=0;
        FAT->id[0]=FAT->id[0]+1;
        MAP->maplist[blocknum]=0;
        blocknum=temp;
    }
    return 0;
}
/*
 * Rename file （ Copy the current file to a new file , And delete the current file ）
 */

void rename(char *str,char *newname){
    cp(str,newname);
    delfile(str);
}

/**
 Exit the system 
*/
int exit()
{
    fp=fopen(FilePath,"w+");
    fwrite(file,sizeof(char),DISK_SIZE,fp);
    fclose(fp);
    free(file);
    return 1;
}


void welcome()
{
    // Welcome list 

    printf("--------------------------------------------------\n");
    printf("\n Here are the instructions \n");
    printf("format          :  Format the disk .\n");
    printf("exit            :  Safely exit the file system , Save information .\n");
    printf("mkdir  dirname  ;  Create subdirectories .\n");
    printf("rmdir  dirname  :  delete a sub dir .\n");
    printf("ls     dirname  :  Display the information under the current directory .\n");
    printf("cd     dirname  :  Change the current directory .\n");
    printf("create filename length :  Create a new file .\n");
    printf("rm     filename :  Delete file .\n");
    printf("cp oldname newname:  Copy file .\n");
    printf("rename oldname newname :  Rename file .\n");
    printf("\n--------------------------------------------\n");

    // Apply for virtual space 
    file=(char *)malloc(DISK_SIZE*sizeof(char));

    // load 
    if((fp=fopen(FilePath,"r"))!=NULL)
    {
        fread(file,sizeof(char),DISK_SIZE,fp);
        printf(" Load disk file %s File successfully , Now you can operate \n\n",FilePath);
    }else
    {
        printf(" This is the first time to use a file management system ");
    }


}

int main()
{
    int length;
    char newname[20];
    welcome();
    format();
    while(1)
    {
        cout<<CURRENT<<"#";
        cin>>cmd;
        if(strcmp(cmd,"format")==0){
            free(file);
            file=(char*)malloc(DISK_SIZE*sizeof(char));  // Reallocate space 
            format();
        }else if(strcmp(cmd,"mkdir")==0)
        {
            scanf("%s",command);
            mkdir(command);
        }else if(strcmp(cmd,"rmdir")==0)
        {
            scanf("%s",command);
            rmdir(command);
        }
        else if(strcmp(cmd,"ls")==0)
        {
            listshow();
        }else if(strcmp(cmd,"cd")==0)
        {
            scanf("%s",command);
            changedir(command);
        }else if(strcmp(cmd,"create")==0)
        {
            cin>>command>>length;
            create(command,length);
        }else if(strcmp(cmd,"cp")==0)
        {
            cin>>command>>newname;
            cp(command,newname);
        }else if(strcmp(cmd,"rm")==0)
        {
            scanf("%s",command);
            delfile(command);
        }
        else if (strcmp(cmd,"rename")==0){
            cin>>command>>newname;
            rename(command,newname);
        }
        else if(strcmp(cmd,"exit")==0){
            exit();
            break;
        }
        else {
            printf(" Invalid instructions , Please re-enter :\n");
        }
    }
    printf("Thank you for using my file system!\n");
    return 0;
}