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CONTRIBUTING.md

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HACKING

Build

make              # normal build
make debug        # with symbols
make asan         # AddressSanitizer
make release      # optimized

Test

./test_basic.sh           # functional tests
./test_stress.sh 20 60    # 20 clients, 60 seconds

Debug

# Memory leaks
ASAN_OPTIONS=detect_leaks=1 ./tnt

# Or use valgrind
make valgrind
valgrind --leak-check=full ./tnt

# Static analysis
make check

Architecture

main.c           → entry point, signal handling
ssh_server.c     → SSH protocol, client threads
chat_room.c      → client list, message broadcast
message.c        → persistent storage
tui.c            → terminal rendering
utf8.c           → UTF-8 string handling

Thread Safety

  • g_room->lock: RWlock for client list and messages
  • client->ref_lock: Mutex for reference counting
  • Each client runs in detached thread
  • Reference counting prevents use-after-free

Memory Management

  • Clients: ref-counted, freed when ref==0
  • Messages: fixed ring buffer (MAX_MESSAGES)
  • No dynamic string allocation

Known Limits

  • Max 64 clients (MAX_CLIENTS)
  • Max 100 messages in memory (MAX_MESSAGES)
  • Max 1024 bytes per message (MAX_MESSAGE_LEN)
  • Max 64 bytes username (MAX_USERNAME_LEN)

Common Bugs to Avoid

  1. Don't use strtok() on client data - use strtok_r() or copy first
  2. Always increment ref_count before using client outside lock
  3. Check SSH API return values (can be SSH_ERROR, SSH_AGAIN, or negative)
  4. UTF-8 chars are multi-byte - use utf8_* functions

Adding Features

  1. Add new command in execute_command() (ssh_server.c:190)
  2. Add new mode in client_mode_t enum (common.h:30)
  3. Add new vim key in handle_key() (ssh_server.c:220)

Debugging Tips

# Find memory issues
make asan
ASAN_OPTIONS=detect_leaks=1:abort_on_error=1 ./tnt

# Check thread issues
gcc -fsanitize=thread ...

# Profile
gcc -pg ...
./tnt
gprof tnt