C语言实现操作系统文件系统源代码分析

#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  fpaddr;                /*file physical address*/
   int  flength;               /*file length*/
   int  fmode;   /*file mode:0-Read Only;1-Write Only;2-Read and Write(default);*/
   char fname[MAXNAME];        /*file name*/
  } OSFILE;

typedef struct     /*the structure of OSUFD*/
  {char ufdname[MAXNAME];   /*ufd name*/
   OSFILE ufdfile[MAXCHILD];   /*ufd own file*/
  }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*/
OSUFD_LOGIN ufd_lp;

int ucount=0;  /*the count of mfd's ufds*/
int fcount[MAXCHILD];  /*the count of ufd's files*/
int loginsuc=0; /*whether login successfully*/
char username[MAXNAME];  /*record login user's name22*/
char dirname[MAXNAME];/*record current directory*/
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 LoginF();  /*LOGIN FileSystem*/
 void DirF();  /*Dir FileSystem*/
 void CdF();  /*Change Dir*/
 void CreateF();  /*Create File*/
 void DeleteF(); /*Delete File*/
 void ModifyFM(); /*Modify FileMode*/
 void OpenF();  /*Open File*/
 void CloseF();  /*Close File*/
 void ReadF(); /*Read File*/
 void WriteF(); /*Write File*/