Systems Programming Labs (TUM)

This repository contains solutions for the Systems Programming practical course at TUM.

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Repository Structure

.
├── .gitignore
├── Makefile
├── README.md
├── task00-sort/
├── task01-syscalls/
├── task02-fileio/
├── task03-processes/
├── task04-concurrency/
├── task05-memory/
├── task06-sockets/
└── task07-llvm/

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Task Matrix

Task	Topic	Primary output	Key requirements
Task 00	External sorting	task00-sort/build/sort	C++17, POSIX
Task 01	System calls and tracing	Libraries and tracer under task01-syscalls/build/	Linux x86-64, ptrace
Task 02	In-memory FUSE filesystem	task02-fileio/build/memfs	FUSE 2.x, /dev/fuse
Task 03	Shell and process management	task03-processes/build/shell	Flex, Bison, libfl
Task 04	Concurrent data structures	Libraries under task04-concurrency/build/	C11 atomics
Task 05	Custom allocator	task05-memory/build/libmymalloc.so	GNU11, pthreads, sbrk()
Task 06	TCP and Protocol Buffers	Programs and library under task06-sockets/build/	C++17, Protobuf, protoc
Task 07	LLVM passes	Plugins and runtime under task07-llvm/build/	LLVM/Clang 16, CMake, Ninja

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Tasks

task00-sort

• External sort implementation under memory constraints
• Supports ascending and reverse order (-r)

See task00-sort.

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task01-syscalls

• System call wrappers using syscall()
• Direct syscall invocation via inline assembly
• Minimal syscall tracer using ptrace()

See task01-syscalls.

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task02-fileio

• In-memory filesystem implemented using FUSE
• Supports hierarchical files and directories
• Read / write / append operations
• Symbolic links and filesystem statistics
• Log-based crash recovery (operation replay)

See task02-fileio.

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task03-processes

• Unix-like shell implementation
• Multi-stage pipeline execution using pipe
• Input / output redirection
• Background process execution
• Builtin process management commands:
  • wait
  • kill
  • exit
• Flex/Bison-based command parser

See task03-processes.

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task04-concurrency

• Spinlock implementation using C11 atomics
• Lock-based hashmap with per-bucket locking
• Lock-free hashmap using compare-and-swap (CAS)
• Logical deletion and physical unlinking

See task04-concurrency.

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task05-memory

• Custom implementations of malloc, calloc, realloc, and free
• First-fit allocation with block splitting and coalescing
• Multiple cache-line-aligned arenas with per-arena locking
• Thread-local arena assignment
• Contention-sensitive heap reservation

See task05-memory.

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task06-sockets

• Multithreaded TCP client-server application
• Protocol Buffers message serialization
• Length-prefixed message framing over TCP
• Fixed server worker pool with round-robin connection assignment
• I/O multiplexing using poll()
• Atomic shared counter with ADD, SUB, and TERMINATION operations

See task06-sockets.

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task07-llvm

• LLVM dead code elimination pass
• Removal of trivially dead instructions, redundant branches, and simple dead stores
• Runtime instrumentation for heap and stack memory accesses
• Detection of out-of-bounds accesses and use-after-free
• Ordered allocation tracking for efficient address lookup

See task07-llvm.

Build

Build every assignment from the repository root:

make

Build one assignment by using its directory name as the target:

make task00-sort

The task Makefiles remain independently usable, for example make -C task00-sort. All generated files are placed under the corresponding task's build/ directory. Build requirements differ by task; consult the task README before building.

Remove every generated build directory with:

make clean

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Usage

Refer to the linked task README for exact commands, arguments, outputs, and limitations.

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Notes

• Target platform: Linux x86-64
• Languages: C / C++
• Each task is independent and can be built separately.
• Source files live under src/, public headers under include/, protocol definitions under proto/, and supplementary material under examples/ or docs/ where applicable.
• Generated files are confined to task-local build/ directories and are not tracked.