Operating Systems Course - Homework Assignments

This repository contains homework assignments for an Operating Systems course, covering fundamental OS concepts through practical programming exercises.

Overview

The repository is organized into 7 homework assignments (hw1-hw7), each focusing on different aspects of operating systems:

• hw1: Basic file operations and memory management
• hw2: Text User Interface (TUI) with ncurses
• hw3: Multi-process programming and signal handling
• hw4: Inter-Process Communication (IPC) with message passing and shared memory
• hw5: Multi-thread programming with pthreads
• hw6: Virtual Memory operations
• hw7: File system operations (PNG ExifTool and custom ls implementation)

Project Structure

os/
├── hw1/          # Basic file operations (fopen, malloc)
├── hw2/          # Text User Interface with ncurses
├── hw3/          # Multi-process programming and signals
├── hw4/          # IPC with message passing and shared memory
├── hw5/          # Multi-thread programming
├── hw6/          # Virtual Memory
├── hw7/          # File system operations
└── README.md     # This file

Prerequisites

• Compiler: GCC (GNU Compiler Collection)
• C Standard: C11 or later
• Libraries:
  • ncurses (for hw2)
  • pthread (for hw5)
  • Standard POSIX libraries

Installing Dependencies

On Ubuntu/Debian:

sudo apt-get update
sudo apt-get install build-essential libncurses5-dev

On Fedora/RHEL:

sudo dnf install gcc make ncurses-devel

Homework Assignments

Homework 1: Basic File Operations

Topics: File I/O, memory allocation

Files:

• main.cpp - Basic Hello World program
• fopen.cpp - File opening operations
• malloc.cpp - Memory allocation examples

Compilation:

cd hw1
gcc -o main main.cpp
gcc -o fopen fopen.cpp
gcc -o malloc malloc.cpp

Homework 2: Text User Interface

Topics: Terminal control, ncurses library, keyboard input handling

Files:

• main.cpp - Interactive TUI application with colored clock display

Features:

• Real-time clock display
• Color cycling animation
• Arrow key navigation
• 'q' to quit

Compilation:

cd hw2
gcc -o main main.cpp -lncurses

Usage:

./main
# Use arrow keys to move the clock, 'q' to quit

Homework 3: Multi-process Programming and Signal Handling

Topics: Process creation (fork), process synchronization (wait), signal handling

Files:

• hw3_1.c - Fork and process synchronization example
• hw3_2.c - Signal handling example

Compilation:

cd hw3
gcc -o hw3_1 hw3_1.c
gcc -o hw3_2 hw3_2.c

Homework 4: IPC with Message Passing and Shared Memory

Topics: FIFOs (named pipes), shared memory, inter-process communication

Files:

• hw4_1.cpp - FIFO-based message passing
• hw4_2.cpp - Shared memory implementation
• hw4_test1, hw4_test2.c - Test programs

Compilation:

cd hw4
gcc -o hw4_1 hw4_1.cpp
gcc -o hw4_2 hw4_2.cpp

Homework 5: Multi-thread Programming

Topics: POSIX threads (pthreads), thread synchronization, parallel algorithms

Files:

• hw5_1.c - Multi-threaded merge sort implementation
• hw5_2.c - Additional threading exercises
• testcase.txt - Test data

Compilation:

cd hw5
gcc -o hw5_1 hw5_1.c -lpthread
gcc -o hw5_2 hw5_2.c -lpthread

Homework 6: Virtual Memory

Topics: Memory-mapped files, shared memory operations

Files:

• hw6_write1.c, hw6_write2.c - Programs that write to shared memory
• hw6_read1.c, hw6_read2.c - Programs that read from shared memory
• Makefile - Build automation

Compilation and Usage:

cd hw6
make              # Compile all programs
make run          # Run all programs in sequence
make clean        # Clean up executables and shared files

Available Makefile targets:

• make all - Compile all programs (default)
• make run - Compile and run all programs
• make run-write1, make run-read1 - Run individual programs
• make clean - Remove executables and shared files
• make help - Show all available targets

Homework 7: File System Operations

Topics: Binary file parsing, PNG format, directory operations, file metadata

Files:

• hw7_1.c - PNG ExifTool (extracts metadata from PNG files)
• hw7_2.c - Custom ls implementation
• hw7_1_imgs/ - Test PNG images
• Makefile - Build automation
• hw7_111550073.md - Detailed report and documentation

Compilation and Usage:

cd hw7
make              # Compile both programs
make test1        # Test PNG ExifTool with all images
make test2        # Test custom ls on hw7_1_imgs directory
make compare      # Compare custom ls output with standard ls -l
make clean        # Clean up executables

Part I - PNG ExifTool:

./hw7_1 <image_file> <output_file>
# Example:
./hw7_1 ./hw7_1_imgs/1.png output.md

Part II - Custom ls:

./hw7_2 <directory>
# Example:
./hw7_2 ./hw7_1_imgs

Features:

• PNG file format parsing (magic number, IHDR chunk, metadata extraction)
• Endianness conversion (big-endian to little-endian)
• Directory listing with detailed file information
• File permissions display (including SUID, SGID, sticky bits)
• File type detection (regular files, directories, links, etc.)

Building and Running

Individual Homework

Each homework directory contains its own source files. Navigate to the specific homework directory and compile:

cd hw<number>
gcc -Wall -Wextra -o <executable> <source_file.c> [additional_flags]

Using Makefiles

Some homeworks (hw6, hw7) include Makefiles for easier compilation:

cd hw<number>
make

Common Compilation Flags

• -Wall - Enable all common warnings
• -Wextra - Enable extra warnings
• -std=c11 - Use C11 standard
• -lpthread - Link pthread library (for hw5)
• -lncurses - Link ncurses library (for hw2)
• -D_XOPEN_SOURCE=500 - Enable POSIX features (for hw6)

Notes

• Most programs are written in C, with some C++ files in earlier assignments
• All programs follow POSIX standards for portability
• Test files and sample data are included where applicable

Course Materials

The repository also includes PDF lecture slides:

• Environment Setup
• Text User Interface
• Multi-process Programming and Signal Handling
• IPC with Message Passing and Shared Memory
• Multi-thread Programming
• Virtual Memory
• File system operations