File System Implementation

A virtual file system implemented in Python built for educational purposes.

A file system serves as the interface between an operating system and the storage device. Its role is to establish a logical representation of the storage device. Without the file system, you would have to manually write to the storage device.

Various operating systems have different file system implementations. The goal of this project is to understand how file systems are implemented. The entire implementation is done in software.

Usage

To use this program, all you need is Python 3.8 and higher. No external dependencies are required.

git clone https://github.com/EteimZ/fs_impl
cd fs_impl
python main.py

Explanation

The repository currently has four major classes:

• SimpleFS
• Storage
• Block
• File

SimpleFS is the file system implementation. It contains a single-level directory. This implementation uses non-contiguous memory allocation, which is implemented using a linked list. It communicates with the Storage which is a virtual representation of a storage device(Hard disk or Flash drive). When the SimpleFs class is created it creates blocks. Which are a group of Block. These blocks map to the storage device. A File is a group of related blocks.

Example

First we import our required classes:

from filesystem import SimpleFS, Storage

Then we create our storage device:

storage = Storage("store.bin", 10)
storage.create()

The Storage class is creating a file called store.bin. Which will be used to persist the memory. We are also creating it with a size of 10.

Now let's create a our file system and asign our created storage to it:

fs = SimpleFS(storage=storage)

By default a simple file system sets it block size to 5. This means each block size can have only 5 bytes.

Let's create a file:

file_content = "hello world"

fs.create("whatever.txt", file_content)

The fs.create method is used to create a file.

file_obj = fs.open("whatever.txt")

The fs.open method is used to get access to a file object which is an Instance of File.

We can read from it:

content = file_obj.read()

We can write to it as well:

file_obj.write("Writing to the file.")

The Block class is not directly accessible.

Resources

• File system explanation by ExplainingComputers
• Files and File Systems by Crash Course
• File Allocation Table explanation by udacity.