CPS: Systems Programming & Embedded Exercises

Systems Programming Exercises — Hands-on C exercises covering algorithms, process management, IPC, file I/O, and dynamic libraries.

---

🎯 Overview

Collection of systems programming exercises in C covering fundamental OS concepts: process management (fork, exec, wait), inter-process communication (pipes, shared memory), file I/O, dynamic library creation, and algorithmic problem solving.

---

📁 Exercise Catalog

🧮 Algorithms & Data Structures

File	Topic	Concepts
ValidMountainArray.c	LeetCode 941	Two-pointer array validation
insertion_sort_list.c	Linked List Sort	Insertion sort on singly linked list
sorting_algorithms.h	Sorting Utilities	Sorting algorithm declarations

🔄 Process Management

File	Topic	Concepts
Exercise_fork_wait_execve.c	Process Creation	fork(), execvp(), wait()
Exercise_find_a_file_in_the_PATH.c	PATH Resolution	PATH env var, access(), execve()
Exercise_super_simple_shell.c	Shell Implementation	Command parsing, builtins, execution

📡 Inter-Process Communication (IPC)

File	Topic	Concepts
pipe.c	Unnamed Pipes	pipe(), fork(), read(), write()
cdl.c	Dynamic Library Loading	dlopen(), dlsym(), dlclose()
functionpointers.c	Function Pointers	Callback patterns, qsort comparator

🔧 System Programming

File	Topic	Concepts
fileio.c	File I/O	open(), read(), write(), lseek(), close()
fileio.c	File Operations	stat(), fstat(), permissions
exec.c	Exec Family	execl(), execv(), execle(), execve()
unsetenv.c	Environment	unsetenv(), getenv(), setenv()
oflags.md	Open Flags	O_RDONLY, O_WRONLY, O_CREAT, O_APPEND
stat.md	File Status	stat(), S_IFMT, S_IRUSR, etc.

🧵 Concurrency & Synchronization

File	Topic	Concepts
stack.c	Stack Implementation	Linked list stack, push/pop
split.c	String Splitting	strtok(), custom delimiters
msprintf.c	Custom printf	Variadic functions, format parsing
randnums.c	Random Numbers	rand(), srand(), /dev/urandom

🐍 Python Integration

File	Topic	Concepts
100-tests.py	C-Python FFI	ctypes, shared library loading

---

🛠 Tech Stack

Category	Technologies
Language	C (C89/gnu89 standard)
Compiler	gcc -Wall -Wextra -Werror -pedantic -std=c89
Build	Makefiles, manual compilation
Debugging	gdb, valgrind
Dynamic Loading	libdl (dlopen, dlsym)
Python FFI	ctypes

---

🚀 Quick Start

git clone https://github.com/oovaa/cps.git
cd cps

# Compile a specific exercise
gcc -Wall -Wextra -Werror -pedantic -std=c89 ValidMountainArray.c -o mountain
./mountain

# Compile with dynamic library
gcc -shared -fPIC -o dlib.so functionpointers.c
python3 100-tests.py

# Compile pipe exercise
gcc -Wall -Wextra -Werror -pedantic -std=c89 pipe.c -o pipe
./pipe

---

🧪 Testing & Debugging

# Compile with debug symbols
gcc -g -Wall -Wextra -Werror -pedantic -std=c89 Exercise_fork_wait_execve.c -o shell

# Debug with GDB
gdb ./shell

# Memory leak check
valgrind --leak-check=full --show-leak-kinds=all ./pipe

---

📚 Learning Outcomes

• ✅ Process Management: fork(), exec(), wait(), waitpid(), zombie/orphan handling
• ✅ IPC Mechanisms: Pipes (unnamed/named), shared memory, signals
• ✅ Dynamic Loading: dlopen(), dlsym(), dlclose(), plugin architectures
• ✅ File I/O: Low-level open/read/write/lseek/close vs stdio
• ✅ Environment Management: getenv, setenv, unsetenv, PATH resolution
• ✅ Shell Implementation: Command parsing, builtins, pipeline execution
• ✅ Memory Management: Manual allocation, leak detection with Valgrind
• ✅ C-Python FFI: ctypes for calling C from Python

---

📂 Project Structure

cps/
├── *.c                 # C exercise files
├── *.h                 # Header files
├── *.md                # Documentation (oflags.md, stat.md)
├── *.py                # Python test scripts
├── Makefile            # Build automation (if present)
├── dlib.so             # Dynamic library (built)
├── LICENSE
└── README.md

---

📚 Learning Resources

• Advanced Programming in the UNIX Environment (APUE)
• The Linux Programming Interface
• Beej's Guide to Unix IPC
• Linux man pages

---

📄 License

MIT License - see LICENSE for details.

---

👤 Author

Omar Abdulrahim
GitHub: @oovaa