INF Senior Project

Martin Nestorov

About me!

I like Linux
Interested in Low-level System
Fancies terminals
Needs a website and a good CV
Can program

Interactive CV

A web application, showing a terminal emulator, sitting on top of a virtual file system, with an "old-fashioned"-themed console.

Perfect for CV-oriented content!

Specification and Analysis

I've set out a few goals with this

I want this project to be:

From a functional standpoint

Simple and readable interface
Be responsive to all inputs
Hold data in files
Be robust!

And speaking non-functionally

Lightning fast!
Must have high code quality
Smart and non-intrusive UI

Use cases

Data pipeline

Architecture of Software

We can view the app in different ways!

As an MVC app

As a modular system

The M-Tree!

The core of the framework revolves around the VFS

wrapped up->(VFS = B+ Tree + Doubly Linked List)

Comparison between M-Tree and B+ Tree

B+ Tree:

Has constraints.
Is self balancing.
Does traversal from root.
Leaf nodes hold numerical data

M-Tree:

Has no constrains.
Does not balance.
Has lateral and horizontal movement.
Leaf nodes hold iNodes (files).

This is the general form

Algorithms

Tree traversal
Relative path resolution
Directory and file mappings
Individual commands and argument handling
Remote access

Tree traversal

Relative path resolution

We have 8 cases to handle

# if
ls

awards
education
experience

# then
cd ./awards/../awards/.././education

Directory and file mappings

# we have this
/education /experience /experience/projects /experience/skills /awards
# mapped to this
/education/edu.txt /experience/projects/my_projects.txt
/experience/skills/soft_skills.txt /experience/skills/hard_skills.txt
/experience/skills/languages/langs.txt

Individual commands and argument handling

Many, many commands

ls
cd
rm
touch
cat
pwd
mkdir
rmdir
echo
and more!

Remote access

Security features

Since all of the data is text based and parsed only on a command based system there is no worry that someone might execute malicious scripts on the host!

No forkbomb!

No malware!

No rm -rf /

Implementation

Everything developed with Emacs + xterm + Arch Linux with:

Some demo code

const express = require('express');

const port = 3000;

let app = express();
app.use(logger('dev'));
app.use(express.json());
app.use(express.static(path.join(__dirname, '.')));
app.use(express.static(path.join(__dirname, 'html')));
app.use(express.static(path.join(__dirname, 'css')));
app.use(express.static(path.join(__dirname, 'src')));

I had a lot of problems with references!!

user.prototype.getDirs = function() {
    return JSON.parse(JSON.stringify(this.dirs));
};

M-Tree navigation

mTree.prototype.moveTo = function(dir) {
    let workingDir = dir.shift();
    if (dir.length === 0) {
	let nextSubtree = this.subtrees.find(s => s.name === workingDir);
	if (!nextSubtree) {
	    throw Error('directory doesn\'t exist.');
	}
	return nextSubtree;
    } else {
	let nextSubtree = this.subtrees.find(s => s.name === workingDir);
	return nextSubtree.moveTo(dir);
    }
};

M-Tree directory creation

mTree.prototype.addSubtree = function(dir, parent) {
    let workingDir = dir.shift();
    if (this.subtrees.find(s => s.name === workingDir)) {
	if (dir.length === 0) {
	    throw Error('File exists');
	} else {
	    let nextSubtree = this.subtrees.find(x => x.name === workingDir);
	    nextSubtree.addSubtree(dir, nextSubtree);
	}
    } else {
	this.subtrees.push(new mTree(workingDir));
	let nextSubtree = this.subtrees.find(x => x.name === workingDir);
	nextSubtree.parenttree = parent;
	nextSubtree.fullpath = nextSubtree.getFullPath(nextSubtree);
	if (dir.length > 0) {
	    nextSubtree.addSubtree(dir, nextSubtree);
	}
    }
};

Path resolution

for (let i = 0; i < d.length; i++) {
    if (d[i] === '.') {
	// do nothing
    } else if (d[i] === '..') {
	if (wdStree.parenttree.name === 'root' || wdStree.name === 'root') {
	    wd = ['/'];
	    wdStree = jvfs.getWdSubtree(wd);
	} else {
	    wd = wdStree.parentree.fullpath.slice();
	    wdStree = jvfs.getWdSubtree(wd);
	}
    } else {
	if (wdStree.subtrees.find(s => s.name === d[i])) {
	    wd = wdStree.fullpath.concat(d[i]);
	} else {
	    wd.push(d[i]);
	}

Testing

I was my own QA Engineer!

Tested each command combination on both a real terminal and compared with the applications terminal.

Some stress testing as well

// [TEST]
// Create 10 000 files
this.create10000();

// [TEST Implementation]
jayVFS.prototype.create10000 = function() {
    for (let i = 0; i < 10000; i++) {
	this.createFile(['awards', 'file' + i]);
    }
};

// [TEST]
this.create1mil();

// [TEST Implementation]
jayVFS.prototype.create1mil = function() {
    // Read complete documentation
    let lines = fs.readFileSync('./README.md', 'utf8', function(){});

    // Create 1000 directories
    for (let j = 0; j < 10000; j++) {

	this.mtree.addSubtree(['dir' + j], this.mtree);

	// Create in each directory 1000 files
	// all filed with the whole documentation
	// of this project
	for (let i = 0; i < 10000; i++) {
	    let f = this.createFile(['awards', 'file' + i]);
	    f.append(lines);
	}
    }
};