操作系统磁盘文件管理源码.doc

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#include
#include
#include

#define MEM_D_SIZE 1024*1024 //总磁盘空间为1M
#define DISKSIZE 1024 //磁盘块的大小1K
#define DISK_NUM 1024 //磁盘块数目1K
#define FATSIZE DISK_NUM*sizeof(struct fatitem) //FAT表大小
#define ROOT_DISK_NO FATSIZE/DISKSIZE+1 //根目录起始盘块号
#define ROOT_DISK_SIZE sizeof(struct direct) //根目录大小
#define DIR_MAXSIZE 1024 //路径最大长度为1KB
#define MSD 5 //最大子目录数5
#define MOFN 5 //最大文件深度为5
#define MAX_WRITE 1024*128 //最大写入文字长度128KB

struct fatitem /* size 8*/
{
int item; /*存放文件下一个磁盘的指针*/
char em_disk; /*磁盘块是否空闲标志位 0 空闲*/
};

struct direct
{
/*-----文件控制快信息-----*/
struct FCB
{
char name[9]; /*文件/目录名 8位*/
char property; /*属性 1位目录 0位普通文件*/
int size; /*文件/目录字节数、盘块数)*/
int firstdisk; /*文件/目录起始盘块号*/
int next; /*子目录起始盘块号*/
int sign; /*1是根目录 0不是根目录*/

}directitem[MSD+2];

};

struct opentable
{
struct openttableitem
{
char name[9]; /*文件名*/
int firstdisk; /*起始盘块号*/
int size; /*文件的大小*/
}openitem[MOFN];
int cur_size; /*当前打文件的数目*/
};

struct fatitem *fat; /*FAT表*/
struct direct *root; /*根目录*/
struct direct *cur_dir; /*当前目录*/
struct opentable u_opentable; /*文件翻开表*/
int fd=-1; /*文件翻开表的序号*/
char *bufferdir; /*记录当前路径的名称*/
char *fdisk; /*虚拟磁盘起始地址*/

void initfile();
void format();
void enter();
void halt();
int create(char *name);
int open(char *name);
int close(char *name);
int write(int fd,char *buf,int len);
int read(int fd,char *buf);
int del(char *name);
int mkdir(char *name);
int rmdir(char *name);
void dir();
int cd(char *name);
void print();
void show();

void initfile()
{
fdisk = (char *)malloc(MEM_D_SIZE*sizeof(char)); /*申请 1M空间*/
format();

}

void format()
{
int i;
FILE *fp;

fat = (struct fatitem *)(fdisk+DISKSIZE); /*计算FAT表地址，引导区向后偏移 1k)*/
/*-----初始化FAT表------------*/
fat[0].item=-1; /*引导块*/
fat[0].em_disk='1';

for(i=1;iISK_NUM;i++)
{
fat[i].item = -1;
fat[i].em_disk = '0';
}
/*-----------------------------------------------*/
root = (struct direct *)(fdisk+DISKSIZE+FATSIZE); /*根目录的地址*/
/*初始化目录*/
/*---------指向当前目录的目录项---------*/
root->directitem[0].sign = 1;
root->directitem[0].firstdisk = ROOT_DISK_NO;
strcpy(root->directitem[0].name,".");
root->directitem[0].next = root->directitem[0].firstdisk;
root->directitem[0].property = '1';
root->directitem[0].size = ROOT_DISK_SIZE;
/*-------指向上一级目录的目录项---------*/
root->directitem[1].sign = 1;
root->directitem[1]firstdisk = ROOT_DISK_NO;
strcpy(root->directitem[1].name,"..");
root->directitem[1].next = root->directitem[0].firstdisk;
root->directitem[1].property = '1';
root->directitem[1].size = ROOT_DISK_SIZE;
if((fp = fopen("disk.dat","wb"))==NULL)
{
printf("Error:\n Cannot open file \n");
return;
}
for(i=2;idirectitem[i].sign = 0;
root->directitem[i].firstdisk = -1;
strcpy(root->directitem[i].name,"");
root->directitem[i].next = -1;
root->directitem[i].property = '0';
root->directitem[i].size = 0;
}

if((fp = fopen("disk.dat","wb"))==NULL)
{
printf("Error:\n Cannot open file \n");
return;
}
if(fwrite(fdisk,MEM_D_SIZE,1,fp)!=1) /*把虚拟磁盘空间保存到磁盘文件中*/
{
printf("Error:\n File write error! \n");
}

fclose(fp);

}
void enter()
{
FILE *fp;
int i;

fdisk = (char *)malloc(MEM_D_SIZE*sizeof(char)); /*申请 1M空间*/
if((fp=fopen("disk.dat","rb"))==NULL)
{
printf("Error:\nCannot open file\n");
return;
}
if(!fread(fdisk,MEM_D_SIZE,1,fp)) /*把磁盘文件disk.dat 读入虚拟磁盘空间(存)*/
{
printf("Error:\nCannot read file\n");
exit(0);
}
fat = (struct fatitem *)(fdisk+DISKSIZE); /*找到FAT表地址*/
root = (struct direct *)(fdisk+DISKSIZE+FATSIZE);/*找到根目录地址*/
fclose(fp);
/*--------------初始化用户翻开表------------------*/
for(i=0;iu_opentable.openitem[i].firstdisk = -1;
u_opentable.openitem[i].size = 0;
}
u_opentable.cur_size = 0;

cur_dir = root; /*当前目录为根目录*/
bufferdir = (char *)malloc(DIR_MAXSIZE*sizeof(char));
strcpy(bufferdir,"Root:");
}

void halt()
{
FILE *fp;
int i;

if((fp=fopen("disk.dat","wb"))==NULL)
{
printf("Error:\nCannot open file\n");
return;
}
if(!fwrite(fdisk,MEM_D_SIZE,1,fp)) /*把虚拟磁盘空间(存)容读入磁盘文件disk.dat */
{
printf("Error:\nFile write error!\n");
}
fclose(fp);

free(fdisk);
free(bufferdir);
return;
}

int create(char *name)
{

int i,j;

if(strlen(name)>8) /*文件名大于 8位*/
return(-1);

for(j=2;jdirectitem[j].name,name))
break;
}
if(j);

for(i=2;idirectitem[i].firstdisk==-1)
break;
}
if(i>=MSD+2) /*无空目录项*/
return(-2);
if(u_opentable.cur_size>=MOFN) /*翻开文件太多*/
return(-3);

for(j=ROOT_DISK_NO+1;jj 后退出*/
{
if(fat[j].em_disk=='0')
break;
}
if(j>=DISK_NUM)
return(-5);
fat[j].em_disk = '1'; /*将空闲块置为已经分配*/
/*-----------填写目录项-----------------*/
strcpy(cur_dir->directitem[i].name,name);
cur_dir->directitem[i].firstdisk = j;
cur_dir->directitem[i].size = 0;
cur_dir->directitem[i].next = j;
cur_dir->directitem[i].property = '0';
/*---------------------------------*/
fd = open(name);
return 0;

}

int open(char *name)
{
int i, j;

for(i=2;iur_dir->directitem[i].name,name))
break;
}
if(i>=MSD+2)
return(-1);
/*--------是文件还是目录-----------------------*/
if(cur_dir->directitem[i].property=='1')
return(-4);

/*--------文件是否翻开-----------------------*/
for(j=0;jstrcmp(u_opentable.openitem[j].name,name))
break;
}
if(j=MOFN) /*文件翻开太多*/
return(-3);

/*--------查找一个空闲用户翻开表项-----------------------*/
for(j=0;jfirstdisk==-1)
break;
}
/*--------------填写表项的相关信息------------------------*/
u_opentable.openitem[j].firstdisk = cur_dir->directitem[i].firstdisk;
strcpy(u_opentable.openitem[j].name,name);
u_opentable.openitem[j].size = cur_dir->directitem[i].size;
u_opentable.cur_size++;
/*----------返回用户翻开表表项的序号--------------------------*/
return(j);
}

int close(char *name)
{
int i;

for(i=0;i=MOFN)
return(-1);
/*--清空该文件的用户翻开表项的容---------------------*/
strcpy(u_opentable.openitem[i].name,"");
u_opentable.openitem[i].firstdisk = -1;
u_opentable.openitem[i].size = 0;
u_opentable.cur_size--;

return 0;
}

int write(int fd, char *buf, int len)
{
char *first;
int item, i, j, k;
int ilen1, ilen2, modlen, temp;
/*----------用 $ 字符作为空格 # 字符作为换行符-----------------------*/
char Space = 32;
char Endter= '\n';

for(i=0;i读取用户翻开表对应表项第一个盘块号-----------------------*/

item = u_opentable.openitem[fd].firstdisk;

/*-------------找到当前目录所对应表项的序号-------------------------*/
for(i=2;idirectitem[i].firstdisk==item)
break;
}
temp = i; /*-存放当前目录项的下标-*/
/*------找到的item 是该文件的最后一块磁盘块-------------------*/
while(fat[item].item!=-1)
{
item =fat[item].item; /*-查找该文件的下一盘块--*/
}

/*-----计算出该文件的最末地址-------*/
first = fdisk+item*DISKSIZE+u_opentable.openitem[fd].size%DISKSIZE;

/*-----如果最后磁盘块剩余的大小大于要写入的文件的大小-------*/
if(DISKSIZE-u_opentable.openitem[fd]size%DISKSIZE>len)
{
strcpy(first,buf);
u_opentable.openitem[fd].size = u_opentable.openitem[fd].size+len;
cur_dir->directitem[temp].size = cur_dir->directitem[temp].size+len;
}
else
{
for(i=0;i<(DISKSIZE-u_opentable.openitem[fd].size%DISKSIZE);i++)
{/*写一局部容到最后一块磁盘块的剩余空间(字节)*/
first[i] = buf [i];
}
/*-----计算分配完最后一块磁盘的剩余空间(字节) 还剩下多少字节未存储-------*/
ilen1 = len-(DISKSIZE-u_opentable.openitem[fd].size%DISKSIZE);
ilen2 = ilen1/DISKSIZE;
modlen = ilen1%DISKSIZE;
if(modlen>0)
ilen2 = ilen2+1; /*--还需要多少块磁盘块-*/

for(j=0;j)
{
for(i=ROOT_DISK_NO+1;i=DISK_NUM) /*--如果磁盘块已经分配完了-*/
return(-1);
first = fdisk+i*DISKSIZE; /*--找到的那块空闲磁盘块的起始地址-*/
if(j==ilen2-1) /*--如果是最后要分配的一块-*/
{
for(k=0;kDISKSIZE-u_opentable.openitem[fd].size%DISKSIZE)-j*DISKSIZE;k++)
first[k] = buf[k];
}
else/*-如果不是要最后分配的一块--*/
{
for(k=0;k/
fat[i].item = -1; /*--它的指针为 -1 (即没有下一块)-*/
}
/*--修改长度-*/
u_opentable.openitem[fd].size = u_opentable.openitem[fd].size+len;
cur_dir->directitem[temp].size = cur_dir->directitem[temp].size+len;
}
return 0;
}

int read(int fd, char *buf)
{
int len = u_opentable.openitem[fd].size;
char *first;
int i, j, item;
int ilen1, modlen;

item = u_opentable.openitem[fd].firstdisk;

ilen1 = len/DISKSIZE;
modlen = len%DISKSIZE;
if(modlen!=0)
ilen1 = ilen1+1; /*--计算文件所占磁盘的块数-*/

first = fdisk+item*DISKSIZE; /*--计算文件的起始位置-*/

for(i=0;isk+item*DISKSIZE;
}
}
return 0;
}

int del(char *name)
{
int i,cur_item,item,temp;

for(i=2;idirectitem[i].name,name))
break;
}
cur_item = i; /*--用来保存目录项的序号,供释放目录中-*/

if(i>=MSD+2) /*--如果不在当前目录中-/
return(-1);

if(cur_dir->directitem[cur_item].property!='0') /*--如果删除的(不)是目录-*/
return(-3);

for(i=0;idirectitem[cur_item].firstdisk;/*--该文件的起始盘块号-*/
while(item!=-1) /*--释放空间,将FAT表对应项进展修改-*/
{
temp = fat[item].item;
fat[item].item = -1;
fat[item].em_disk = '0';
item = temp;
}
/*-----------------释放目录项-----------------------*/
cur_dir->directitem[cur_item].sign = 0;
cur_dir->directitem[cur_item].firstdisk = -1;
strcpy(u_opentable.openitem[cur_item].name,"");
cur_dir->directitem[cur_item].next = -1;
cur_dir->directitem[cur_item].property = '0';
cur_dir->directitem[cur_item].size = 0;

return 0;
}

int mkdir(char *name)
{
int i,j;
struct direct *cur_mkdir;

if(!strcmp(name,"."))
return(-4);
if(!strcmp(name,".."))
return(-4);
if(strlen(name)>8) /*-如果目录名长度大于 8位-*/
return(-1);

for(i=2;idirectitem[i].firstdisk==-1)
break;
}
if(i>=MSD+2) /*-目录/文件已满-*/
return(-2);
for(j=2;j) /*-判断是否有重名-*/
{
if(!strcmp(cur_dir->directitem[j].name,name))
break;
}
if(j=DISK_NUM)
return(-5);
fat[j].em_disk='1'; /*-将该空闲块设置为已分配-*/

/*-------------填写目录项----------*/
strcpy(cur_dir->directitem[i].name,name);
cur_dir->directitem[i].firstdisk=j;
cur_dir->directitem[i].size=ROOT_DISK_SIZE;
cur_dir->directitem[i].next=j;
cur_dir->directitem[i].property='1';

/*-所创目录在虚拟磁盘上的地址(存物理地址)-*/
cur_mkdir=(struct direct *)(fdisk+cur_dir->directitem[i].firstdisk*DISKSIZE);

/*-初始化目录-*/
/*-指向当前目录的目录项-*/
cur_mkdir->directitem[0].sign=0;
cur_mkdir->directitem[0].firstdisk=cur_dir->directitem[i].firstdisk;
strcpy(cur_mkdir->directitem[0].name,".");
cur_mkdir->directitem[0].next=cur_mkdir->directitem[0].firstdisk;
cur_mkdir->directitem[0].property='1';
cur_mkdir->directitem[0].size=ROOT_DISK_SIZE;

/*-指向上一级目录的目录项-*/
cur_mkdir->directitem[1].sign=cur_dir->directitem[0].sign;
cur_mkdir->directitem[1].firstdisk=cur_dir->directitem[0].firstdisk;
strcpy(cur_mkdir->directitem[1].name,"..");
cur_mkdir->directitem[1].next=cur_mkdir->directitem[1].firstdisk;
cur_mkdir->directitem[1].property='1';
cur_mkdir->directitem[1].size=ROOT_DISK_SIZE;
for(i=2;idirectitem[i].sign=0;
cur_mkdir->directitem[i].firstdisk=-1;
strcpy(cur_mkdir->directitem[i].name,"");
cur_mkdir->directitem[i].next=-1;
cur_mkdir->directitem[i].property='0';
cur_mkdir->directitem[i].size=0;
}
return 0;
}

int rmdir(char *name)
{
int i,j,item;
struct direct *temp_dir;
/*-检查当前目录项中有无该目录-*/
for(i=2;idirectitem[i].name,name))
break;
}
if(i>=MSD+2) /*-没有这个文件或目录-*/
return(-1);
if(cur_dir->directitem[i].property!='1')/*-删除的不是目录-*/
return(-3);

/*-判断要删除的目录有无子目录-*/

temp_dir=(struct direct *)(fdisk+cur_dir->directitem[i].next*DISKSIZE);
for(j=2;jdirectitem[j].next!=-1)
break;
}
if(jdirectitem[i].firstdisk;
fat[item].em_disk='0';
/*-修改目录项-*/
cur_dir->directitem[i].sign=0;
cur_dir->directitem[i].firstdisk=-1;
strcpy(cur_dir->directitem[i].name,"");
cur_dir->directitem[i].next=-1;
cur_dir->directitem[i].property='0';
cur_dir->directitem[i].size=0;

return 0;
}

void dir()
{
int i;
for(i=2;i