it_portfolio/content/projects/systems.md

Systems Programming Projects

Low-level work: operating systems, compilers, networking, and performance engineering.

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Tiny HTTP/1.1 Server (C)

A from-scratch HTTP server written in C that handles concurrent connections using epoll on Linux.

What it does:

• Serves static files with correct MIME types
• Handles keep-alive connections
• Parses request headers manually (no third-party parser)
• ~1,200 lines of C — intentionally minimal

Interesting problems solved:

• Non-blocking I/O with an event loop
• Incremental parsing of chunked request bodies
• Safe path traversal (no ../ escapes from the document root)

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Shell Implementation (C)

A POSIX-compatible shell (mysh) supporting pipelines, redirections, background jobs, and a small built-in set.

Supported features:

• Pipelines: cmd1 | cmd2 | cmd3
• I/O redirections: >, >>, <, 2>
• Background jobs: cmd &
• Job control: fg, bg, jobs
• Signal handling (SIGINT, SIGTSTP, SIGHUP)

Focus areas: fork/exec model, waitpid, file descriptor management, signal masking.

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Memory Allocator

A drop-in malloc replacement using mmap-backed free lists with coalescing.

Algorithms implemented:

• First-fit and best-fit strategies (switchable at compile time)
• Boundary-tag coalescing to reduce fragmentation
• Thread-local caches for small allocations (reduces lock contention)

Benchmarked against glibc malloc on synthetic workloads — within 2× for mixed-size allocations.

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Bytecode Interpreter (Python → C)

A small virtual machine that executes a simple bytecode format, written in C. The front-end compiler is written in Python and produces .bco files.

VM features:

• Stack-based architecture (inspired by CPython)
• 30 opcodes: arithmetic, comparisons, jumps, function calls, closures
• Mark-and-sweep garbage collector
• Disassembler for debugging (--disasm flag)

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