1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
|
#include <iostream>
#include <fstream>
#include <string>
#include <vector>
using namespace std;
class Sdisk
{
public:
Sdisk(string disk_name); //default constructor called when file already exists
Sdisk(string disk_name, int number_of_blocks, int block_size); //called when creating a new while from scratch
int getblock(int blocknumber, string& buffer); //retrieves block from disk and stores this information on buffer
int putblock(int blocknumber, string buffer); //writes at specified blocknumber from buffer
int getblocksize();
int getblocknumber();
private:
string diskname; // file name of software-disk
int numberofblocks; // number of blocks on disk
int blocksize; // block size in bytes
};
#ifndef FILESYS_H
#define FILESYS_H
#include <iostream>
#include <fstream>
#include <sstream>
#include <string>
#include <vector>
#include "sdrive.h"
using namespace std;
class Filesys: public Sdisk
{
public:
Filesys(string filename);
int fsclose();
int fssynch();
int newfile(string file);
int rmfile(string file);
int getfirstblock(string file);
int addblock(string file, string buffer);
int delblock(string file, int blocknumber);
int readblock(string file, int blocknumber, string& buffer);
int writeblock(string file, int blocknumber, string buffer);
int nextblock(string file, int blocknumber);
private:
int rootsize; //max number of entries in ROOT
int fatsize; //number of blocks in FAT
vector<string> filenames; //filenames in ROOT
vector<int> firstblocks; //first blocks in ROOT
vector<int> fat;
};
Filesys::Filesys(string filename) : Sdisk(filename)
{
cout << getblocknumber() << endl;
rootsize = (getblocksize()/12);
fatsize = (8*getblocknumber()/getblocksize()) + 1;
cout << "Rootsize " << rootsize << endl;
cout << "Fatsize " << fatsize << endl;
string buffer;
getblock(1, buffer);
if(buffer[0] == '#'){
//file does not exist, so make it
//build the initial root
cout << "Building initial root" << endl;
for (int i = 0; i < rootsize; i++){
filenames.push_back("XXXXX");
firstblocks.push_back(0);
}
//build the FAT
cout << "Building FAT" << endl;
fat.push_back(2 + fatsize);
for(int i = 1; i <= 1 + fatsize; i++){
fat.push_back(1);
}
for(int i = 2 + fatsize; i < getblocknumber(); i++){
fat[i] = i + 1;
//cout << fat[i] << endl;
}
fat[fat.size() - 1] = 0;
}
else{
//since file exists, read in root and fat
cout << "File exists, reading in ROOT and FAT" << endl;
string buffer;
istringstream readroot(buffer);
readroot.str(buffer);
//read the root directory
for(int i = 0; i < rootsize; i++){
readroot >> filenames[i] >> firstblocks[i];
}
//read the FAT
string fatbuffer;
for(int i = 0; i < fatsize; i++){
string s;
getblock(i + 2, s);
fatbuffer += s;
}
istringstream fatstream;
fatstream.str(fatbuffer); //load buffer into fatstream
for(int i = 0; i < getblocknumber(); i++){
int temp;
fatstream >> temp;
fat.push_back(temp);
}
//cout << fatbuffer << endl;
}
fssynch();
}
int Filesys::fssynch()
{
//write updated root to disk
ostringstream rootstream;
for(int i = 0; i < rootsize; ++i){
rootstream << filenames[i] << " " << firstblocks[i] << " ";
//debugger says the seg fault occurs here, why's that??s
}
string root = rootstream.str();
for(long j = root.size(); j < getblocksize(); j++){
root += "#";
}
putblock(1, root);
//write the FAT onto the disk
ostringstream fatstream;
for(int i = 0; i < getblocknumber(); i++){
fatstream << fat[i] << " ";
}
string fatstring = fatstream.str();
for(int i = 0; i < getblocksize(); i++){
fatstring += "#";
}
//writing the substring of the FAT
for(int i = 0, blocks = 2; i < fatsize; i++){
string temp = fatstring.substr(i * getblocksize(), getblocknumber());
putblock(i + blocks, temp);
}
return 1; //successful!
}
//testing main function
#include <iostream>
#include <string>
#include "sdrive.h"
#include "filesys.h"
using namespace std;
int main()
{
Sdisk disk1("disk1",256,128);
Filesys fsys("disk1"); //debugger also says the segmentation fault is here
fsys.newfile("file1");
fsys.newfile("file2");
string bfile;
for (int i=1; i<=1024; i++)
{
bfile+="1";
}
vector<string> blocks=block(bfile,128);
int blocknumber=0;
for (int i=0; i<=blocks.size(); i++)
{
blocknumber=fsys.addblock("file1",blocks[i]);
}
fsys.delblock("file1",fsys.getfirstblock("file1"));
for (int i=1; i<=2048; i++)
{
bfile+="2";
}
for (int i=0; i<=blocks.size(); i++)
{
blocknumber=fsys.addblock("file2",blocks[i]);
}
fsys.delblock("file2",blocknumber);
}
|
