1、实验目的
通过具体的文件存储空间的管理、文件的物理结构、目录结构和文件操作的实现，加深对文件系统内部功能和实现过程的理解。
2、实验内容
- 在内存中开辟一个虚拟磁盘空间作为文件存储器，在上面实现一个简单单用户文件系统。退出时应该将该虚拟文件系统保存到磁盘上，以便下次可以再将它恢复到内存对虚拟磁盘空间中。
- 文件存储空间对分配可以采用显式链接分配或者其他的办法。
- 空闲空间的管理可以选择位示图或者其他的办法。如果采用位示图来管理文件存储空间，并采用显式链接分配方式，那么可以将位示图合并到FAT中。
- 文件目录结构采用多级目录结构。为了简单起见，可以不使用索引结点，其中的每个目录项应包含文件名、物理地址、长度等信息，还可以通过目录项实现对文件对读和写的保护。
- 要求提供以下有关的操作：
√format：对文件存储器进行格式化，即按照文件系统对结构对虚拟磁盘空间进行布局，并在其上创建根目录以及用于管理文件存储空间等的数据结构。
√mkdir：用于创建子目录；
√rmdir：用于删除目录；
√ls：用于显示目录；
√cd：用于更改当前目录；
√create：用于创建文件；
√open：用于打开文件；
√close：用于关闭文件；
√write：用于写文件；
√read：用于读文件
√rm：用于删除文件。
代码
#include <iostream>
#include <vector>
#include <iomanip>
#include <fstream>
using std::string;
using std::vector;
using std::cout;
using std::endl;
using std::cin;
using std::ifstream;
using std::ofstream;
using std::ios;
class FCB{
public:
int first_block;
string fileName;
int size;
int real_size;
FCB(int first_block0,const string &fileName0, int size0, int real_size0):
first_block(first_block0),
fileName(fileName0),
size(size0),
real_size(real_size0*4) {
}
}; //文件控制块
class DirItem { //文件树
string name;
vector<FCB*> files; //目录下的文件
vector<DirItem*> dirs; //目录下的文件夹，树节点
public:
DirItem(const string& name0):name(name0) {}
void addFile(int first_block, const string& fileName,int size, int real_size) {
for (auto i = files.begin(); i != files.end(); i++) {
if ((*i)->fileName == fileName) {
cout << "same file name" << endl;
return;
}
}
files.push_back(new FCB(first_block, fileName, size, real_size));
}
void addDir(DirItem* dir) {
dirs.push_back(dir);
}
vector<DirItem*> getDirs() {
return dirs;
}
vector<FCB*> getFiles() {
return files;
}
string getName() {
return name;
}
void del_file(const string& fileName) {
for (auto i = files.begin(); i != files.end(); i++) {
if ((*i)->fileName == fileName) {
files.erase(i);
break;
}
}
}
void del_dir(const string& fileName) {
for (auto i = dirs.begin(); i != dirs.end(); i++) {
if ((*i)->getName() == fileName) {
dirs.erase(i);
break;
}
}
}
void clear() {
for (DirItem* item : dirs) {
delete item;
}
for (FCB* item : files) {
delete item;
}
dirs.clear();
files.clear();
} //递归删除时用到，删除当前目录下的目录和文件的指针
};
class diskMgr { //磁盘
vector<int> blocks; //fat表
int n = 16;
int block_num = n*n;
int block_size = 4; //每块4B
int disk_capacity = block_num * block_size; //1M
vector<vector<int>> bit_map; //0空，1有，位视图
public:
vector<char> disk;
diskMgr() {
disk = vector<char>(disk_capacity, '\0');
blocks = vector<int>(block_num, -1);
bit_map = vector<vector<int>>(n, vector<int>(n, 0));
}
int getSize(int blockNum) {
int n = 0;
while (blockNum != -1) {
n++;
blockNum = blocks[blockNum];
}
return n;
} //当前块号开始的文件一个有多少块儿
int find_empty_block() {
for (int i = 0; i < n; i++) {
for (int j = 0; j < n; j++) {
if (bit_map[i][j] == 0) {
return n*i+j;
}
}
}
return -1;
}//找到一个空闲盘块，从位视图
void update_bit_map(int x, int notempty) {
int i = x / n,j = x % n;
bit_map[i][j] = notempty;
}//更新位视图
void del(int blockNum) {
while (blockNum != -1) {
for(int i = 0; i < block_size; i++) {
disk[blockNum * block_size + i] = '\0';
}
update_bit_map(blockNum, 0);
int t = blocks[blockNum];
blocks[blockNum] = -1;
blockNum = t;
}
} //删除文件
vector<char> read(int blockNum) {
vector<char> data;
while (blockNum != -1) {
for(int i = 0; i < block_size; i++) {
data.push_back(disk[blockNum * block_size + i]);
}
blockNum = blocks[blockNum];
}
return data;
} //读取文件
int write(vector<char> data) {
int first_block = find_empty_block(); //找到初始位置
if (first_block == -1) return -1;
int len = int(data.size());
int blockn = len%block_size == 0 ? len/block_size : len/block_size+1; //一共需要的盘块儿数
int next_block = first_block;
int temp = next_block;
int fix = (block_size - len % block_size) % block_size;
for (int i = 0; i < fix; ++i) { //数据长度对齐
data.push_back('*');
}
for (int i = 0; i < blockn; i++) { //存数据
if (temp == -1) {
break;
}
next_block = temp;
for (int j = 0; j < block_size; j++) {
disk[next_block*block_size+j] = data[i*block_size+j];
}
update_bit_map(next_block, 1);
temp = find_empty_block();
blocks[next_block] = temp;
}
blocks[next_block] = -1;
return first_block;
}
};
#define chart_head std::left << std::setw(len+1) << std::setfill('-') << ""
#define chart_cell "|" << std::left << std::setw(len) << std::setfill(' ')
class fileMgr {
DirItem * root; //根节点
diskMgr dm;//磁盘管理器
DirItem * cur; //当前命令行执的工作目录
string cur_path; //工作命令
DirItem* addmdir(DirItem * node, string name) {
DirItem* newNode = new DirItem(name);
node->addDir(newNode);
return newNode;
}
public:
fileMgr() {
root = new DirItem("/");
DirItem * temp = addmdir(addmdir(root, "apps"), "tencent");
addmdir(temp, "qq");
addmdir(temp, "qqgame");
addmdir(temp, "qqmusic");
temp = addmdir(root, "docs");
addmdir(temp, "words");
addmdir(temp, "ppts");
addmdir(temp, "excels");
root->addDir(new DirItem("pics"));
root->addDir(new DirItem("musics"));
cur = root;
cur_path = "/";
cout_hint();
} //初始化一些文件夹
void ls() {
int len = 20;
cout
<< chart_head << chart_head << chart_head << chart_head << endl
<< chart_cell << "file/dir name"
<< chart_cell << "type"
<< chart_cell << "size"
<< chart_cell << "real size" << "|" << std::endl
<< chart_head << chart_head << chart_head << chart_head << endl;
vector<DirItem*> dirs = cur->getDirs();
for (auto i = dirs.begin(); i != dirs.end(); i++) {
cout
<< chart_cell << (*i)->getName()
<< chart_cell << "directory"
<< chart_cell << "--"
<< chart_cell << "--" << "|" << std::endl;
}
vector<FCB*> files = cur->getFiles();
for (auto i = files.begin(); i != files.end(); i++) {
cout
<< chart_cell << (*i)->fileName
<< chart_cell << "file"
<< chart_cell << (*i)->size
<< chart_cell << (*i)->real_size << "|" << std::endl;
}
cout
<< chart_head << chart_head << chart_head << chart_head << endl;
cout_hint();
}
void cout_hint() {
cout << "\n" << cur_path << "> ";
} //输出命令行提示符
void cd(string name) {
if (name == "..") {
if(cur_path == "/") {
cout_hint();
} else {
if (*cur_path.rbegin() == '/') {
cur_path.pop_back();
}
cur_path = cur_path.substr(0, cur_path.rfind('/'));
if (cur_path.length() == 0) {
cur_path = "/";
}
cur = find_dir_node(cur_path);
cout_hint();
return;
}
}
DirItem* node = cur;
for(DirItem* item : node->getDirs()){
if (item->getName() == name) {
cur = item;
cur_path += name+"/";
cout_hint();
return;
}
}
cout << "no such dir";
cout_hint();
}
void cdn(string path) {
cur = find_dir_node(path);
if (*path.rbegin() != '/') {
path.push_back('/');
}
if (*path.begin() != '/') {
path = "/" + path;
}
cur_path = path;
cout_hint();
}
DirItem* find_dir_node(string path) {
if (path[0] == '/') {
path = path.substr(1, path.length()-1);
}
if (*path.rbegin() != '/') {
path.push_back('/');
}
int r = 0;
DirItem* node = root;
if (path == "/") return node;
while (r != -1) {
r = path.find('/');
if (r != -1) {
string dir = path.substr(0, r);
bool find = false;
for(DirItem* item : node->getDirs()){
if (item->getName() == dir) {
node = item;
find = true;
break;
}
}
if (!find) {
return nullptr;
}
path = path.substr(r+1, path.length() - r - 1);
} else {
break;
}
}
return node;
}
void create_file(const string& fileName, const vector<char>& data) {
DirItem *node = cur;
if (node != nullptr) {
int fb = dm.write(data);
if(fb == -1) {
cout << "no enough disk storage";
cout_hint();
}
int size = dm.getSize(fb);
node->addFile(fb, fileName, data.size(), size);
}
cout_hint();
}
void create_file(string path, const string& fileName, const vector<char>& data) {
DirItem *node = find_dir_node(path);
if (node != nullptr) {
int fb = dm.write(data);
int size = dm.getSize(fb);
node->addFile(fb, fileName, data.size(), size);
}
}
void create_dir(const string& dirName) {
if (cur != nullptr) {
cur->addDir(new DirItem(dirName));
}
cout_hint();
}
void create_dir(string path, const string& dirName) {
DirItem * node = find_dir_node(path);
if (node != nullptr) {
node->addDir(new DirItem(dirName));
}
}
void del_dir(DirItem* node) {
if (node != nullptr) {
for(FCB* fcb : node->getFiles()) {
dm.del(fcb->first_block);
node->del_file(fcb->fileName);
}
for(auto i : node->getDirs()) {
del_dir(i);
}
node->clear();
}
}
void del_dir(const string& fileName) {
if (cur != nullptr) {
for (auto i : cur->getDirs()) {
if(i->getName() == fileName) {
del_dir(i);
cur->del_dir(i->getName());
cout_hint();
return;
}
}
}
cout << "no such directory";
cout_hint();
}
void del_file(const string& fileName) {
DirItem*node = cur;
if (node != nullptr) {
for(FCB* fcb : node->getFiles()) {
if (fcb->fileName == fileName) {
dm.del(fcb->first_block);
node->del_file(fileName);
cout_hint();
return;
}
}
}
}
void del_file(string path, const string& fileName) {
DirItem*node = find_dir_node(path);
if (node != nullptr) {
for(FCB* fcb : node->getFiles()) {
if (fcb->fileName == fileName) {
dm.del(fcb->first_block);
node->del_file(fileName);
return;
}
}
}
}
void show(const vector<char>& v) {
for (char i : v) {
cout << i;
}
}
void read(const string& fileName) {
if (cur != nullptr) {
for(FCB* fcb : cur->getFiles()) {
if (fcb->fileName == fileName) {
vector<char> data = dm.read(fcb->first_block);
show(data);
cout_hint();
return;
}
}
}
cout << "file not found";
cout_hint();
}
vector<char> read(string path, const string& fileName) {
DirItem*node = find_dir_node(path);
if (node != nullptr) {
for(FCB* fcb : node->getFiles()) {
if (fcb->fileName == fileName) {
return dm.read(fcb->first_block);
}
}
}
return {};
}
};
int main() {
fileMgr fm;
/*ifstream Myfile2;
Myfile2.open("file_sys.disk",ios::binary);
//二进制打开，缺省为文本，ios::out,ios::in,文本输入输出用<<,>>
Myfile2.read((char *)&fm,sizeof(fileMgr));
Myfile2.close();*/
string ins, para;
while(cin >> ins) {
if(ins == "ls") {
fm.ls();
} else if(ins == "cd") {
cin >> para;
fm.cd(para);
} else if (ins == "read") {
cin >> para;
fm.read(para);
} else if (ins == "mkdir") {
cin >> para;
fm.create_dir(para);
} else if (ins == "rmdir") {
cin >> para;
fm.del_dir(para);
} else if (ins == "mkfile") {
cin >> para;
string c = "";
cout << "contents:\n";
string data;
while(c != "#") {
data += c;
std::getline(cin, c);
data += '\n';
}
int k = 0;
while (data[k] == '\n') k++;
data = data.substr(k, data.length()-k);
vector<char> vdata;
for(char i : data) {
vdata.push_back(i);
}
fm.create_file(para, vdata);
} else if (ins == "rmfile") {
cin >> para;
fm.del_file(para);
} else if (ins == "exit" || ins == "quit") {
break;
} else if (ins == "cdn") {
cin >> para;
fm.cdn(para);
} else {
string c;
std::getline(cin, c);
ins += " " + c;
system(ins.c_str());
cout << "unknown cmd:" << ins << endl;
fm.cout_hint();
}
}
/*ofstream file;
file.open("file_sys.disk",ios::binary);
//缓存的类型是 unsigned char *，需要类型转换
file.write((char *)&fm,sizeof(fileMgr)); //winServer为类对象
file.close();*/
return 0;
}
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