二级文件系统C语言代码

实验九 文件系统设计

1．目的和要求

本实验的目的是通过一个简单多用户文件系统的设计，加深理解文件系统

的内部功能和内部实现。

2．实验内容

为 DOS 系统设计一个简单的二级文件系统。要求做到以下几点：

① 可以实现下列几条命令

LOGIN 用户登陆

WRITE 写文件

② 列目录时要列出文件名，物理地址，保护码和文件长度。

③ 源文件可以进行读写保护。

3．实验环境

①PC 兼容机

②Windows、DOS 系统

③TC 语言

4．实验提示

① 首先应确定文件系统的数据结构：主目录、子目录及活动文件等。主目

录和子目录都以文件的形式存放于磁盘，这样便于查找和修改。

//

#include "stdio.h"

#include "string.h"

#include "conio.h"

#include "stdlib.h"

#define MAXNAME 25 /*the largest length of mfdname,ufdname,filename*/

#define MAXCHILD 50 /*the largest child*/

#define MAX (MAXCHILD*MAXCHILD) /*the size of fpaddrno*/

typedef struct /*the structure of OSFILE*/

int flength; /*file length*/

}OSUFD;

typedef struct /*the structure of OSUFD'LOGIN*/

{char ufdname[MAXNAME]; /*ufd name*/

char ufdpword[8]; /*ufd password*/

} OSUFD_LOGIN;

typedef struct /*file open mode*/

{int ifopen; /*ifopen:0-close,1-open*/

int openmode; /*0-read only,1-write only,2-read and write,3-initial*/

}OSUFD_OPENMODE;

OSUFD *ufd[MAXCHILD]; /*ufd and ufd own files*/

int fpaddrno[MAX]; /*record file physical address num*/

OSUFD_OPENMODE ifopen[MAXCHILD][MAXCHILD]; /*record file open/close*/

int wgetchar; /*whether getchar()*/

FILE *fp_mfd,*fp_ufd,*fp_file_p,*fp_file;

void main()

{int i,j,choice1;

char choice[50]; /*choice operation:dir,create,delete,open,delete,modify,read,write*/

int choiceend=1; /*whether choice end*/

char *rtrim(char *str); /*remove the trailing blanks.*/

char *ltrim(char *str); /*remove the heading blanks.*/

void OpenF(); /*Open File*/

void CloseF(); /*Close File*/

void ReadF(); /*Read File*/

void WriteF(); /*Write File*/

void QuitF(); /*Quit FileSystem*/

void help();

if((fp_mfd=fopen("c:\\osfile\\mfd","rb"))==NULL)

{fp_mfd=fopen("c:\\osfile\\mfd","wb");

fclose(fp_mfd);

}

{while (1)

{wgetchar=0;

if (choiceend==1)

{printf("\n\nC:\\%s>",strupr(dirname));} //strupr将所有小写字母转换成大写

else printf("Bad command or file name.\nC:\\%s>",strupr(username));

gets(choice);

strcpy(choice,ltrim(rtrim(strlwr(choice)))); //strlwr将所有大写字母转换成小写

if (strcmp(choice,"dir")==0) choice1=1;

else if(strcmp(choice,"creat")==0) choice1=2;

else if(strcmp(choice,"delete")==0) choice1=3;

else if(strcmp(choice,"attrib")==0) choice1=4;

else if(strcmp(choice,"open")==0) choice1=5;

else if(strcmp(choice,"close")==0) choice1=6;

else if(strcmp(choice,"read")==0) choice1=7;

else if(strcmp(choice,"modify")==0) choice1=8;

else if(strcmp(choice,"exit")==0) choice1=9;

else if(strcmp(choice,"cls")==0) choice1=10;

else if(strcmp(choice,"cd")==0) choice1=11;

else if(strcmp(choice,"help")==0) choice1=20;

else choice1=12;

case 6:choiceend=1;CloseF();if (!wgetchar) getchar();break;

case 7:choiceend=1;ReadF();if (!wgetchar) getchar();break;

case 8:choiceend=1;WriteF();if (!wgetchar) getchar();break;

case 9:printf("\nYou have exited this system.");

QuitF();exit(0);break;

case 10:choiceend=1;system("cls");break;

case 11:CdF();choiceend=1;break;

case 20:help();choiceend=1;break;

default:choiceend=0;

}

printf("\nCd Attrib Creat Modify Read Open Cls Delete Exit Close\n");

}

char *rtrim(char *str) /*remove the trailing blanks.*/

while(n>=0)

{if(*(str+n)!=' ')

break;