Customised Virtual File System (CVFS)

Overview

The Customised Virtual File System (CVFS) is a C++-based, in-memory file system emulator that replicates core UNIX-like file system behaviors. It is designed for educational and research purposes, providing a hands-on understanding of file system internals such as inode management, file operations, and user-space interaction.

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Features

• In-Memory File System: All operations are performed in RAM, with no disk I/O.
• UNIX-like Commands: Supports commands such as creat, open, read, write, ls, stat, fstat, truncate, rm, lseek, close, and closeall.
• Custom Shell Interface: Interactive CLI for file system operations.
• File Metadata Management: Implements superblock, inode table, file table, and UFDT (User File Descriptor Table).
• Permission Handling: Supports read, write, and read-write permissions.
• Resource Management: Handles file descriptors, reference counts, and memory allocation.

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Architecture

• Superblock: Tracks total and free inodes.
• Inode Table: Stores metadata for each file (name, size, type, permissions, etc.).
• File Table: Maintains open file state (offsets, mode, reference count).
• UFDT: Maps file descriptors to file table entries.
• Buffer: Each file has a dedicated buffer for its contents.

For detailed diagrams and flowcharts, see docs/CustomisedVirtualFileSystem_Project_Documation.pdf.

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Getting Started

Prerequisites

• GCC/g++ compiler (Linux/Windows)
• Command-line terminal

Build Instructions

git clone https://github.com/yourusername/CustomisedVirtualFileSystem.git
cd CustomisedVirtualFileSystem/src
g++ Source_Code.cpp -o CVFS

Running the Application

./CVFS

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Usage

Once started, the shell accepts the following commands:

Command	Description	Example Usage
creat <name> <perm>	Create a new file with permissions	creat myfile 3
open <name> <mode>	Open an existing file	open myfile 1
read <name> <bytes>	Read bytes from a file	read myfile 100
write <name>	Write data to a file (prompts for input)	write myfile
ls	List all files	ls
stat <name>	Show file metadata by name	stat myfile
fstat <fd>	Show file metadata by descriptor	fstat 0
truncate <name>	Remove all data from a file	truncate myfile
rm <name>	Delete a file	rm myfile
lseek <name> <off> <whence>	Change file offset	lseek myfile 10 0
close <name>	Close a file	close myfile
closeall	Close all open files	closeall
help	Display help information	help
exit	Exit the shell	exit

Permissions:

• 1 = Read
• 2 = Write
• 3 = Read & Write

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Example Session

Abhishek Atole CVFS :> creat test 3
File is successfully created with file descriptor : 0

Abhishek Atole CVFS :> write test
Enter the data to write file :
Hello, CVFS!
13 bytes gets written successfully in the file

Abhishek Atole CVFS :> read test 13
Hello, CVFS!

Abhishek Atole CVFS :> ls
File Name   Inode number   File iSize   Link iCount
test        1              13           1

Abhishek Atole CVFS :> exit
Thank-you for using My Virtual File System

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Documentation

• Project Documentation PDF
• Architecture Diagrams Folder

Visuals

• Final Run Executable Screenshot:
  

• Hard Disk Info Diagram:
  

• Inode Information Diagram:
  

• RAM Processing Diagram:
  

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Contributing

Contributions, issues, and feature requests are welcome!
Please open an issue or submit a pull request.

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License

This project is licensed under the MIT License.

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Author

Abhishek Atole
LinkedIn • GitHub

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