TNT/src/main.c

#include "common.h"
#include "ssh_server.h"
#include "chat_room.h"
#include "message.h"
#include <signal.h>
#include <unistd.h>

/* Signal handler: must only call async-signal-safe functions.
 * pthread, malloc, printf, exit() are NOT safe here.
 * Just write a message and call _exit() — OS reclaims all resources. */
static void signal_handler(int sig) {
    (void)sig;
    static const char msg[] = "\nShutting down...\n";
    ssize_t ignored = write(STDERR_FILENO, msg, sizeof(msg) - 1);
    (void)ignored;
    _exit(0);
}

int main(int argc, char **argv) {
    int port = DEFAULT_PORT;

    /* Environment provides defaults; command-line flags override it. */
    const char *port_env = getenv("PORT");
    if (port_env) {
        port = atoi(port_env);
    }

    /* Parse command line arguments */
    for (int i = 1; i < argc; i++) {
        if (strcmp(argv[i], "-p") == 0 && i + 1 < argc) {
            port = atoi(argv[i + 1]);
            i++;
        } else if ((strcmp(argv[i], "-d") == 0 ||
                    strcmp(argv[i], "--state-dir") == 0) && i + 1 < argc) {
            if (setenv("TNT_STATE_DIR", argv[i + 1], 1) != 0) {
                perror("setenv TNT_STATE_DIR");
                return 1;
            }
            i++;
        } else if (strcmp(argv[i], "-h") == 0 || strcmp(argv[i], "--help") == 0) {
            printf("TNT - Terminal Network Talk\n");
            printf("Usage: %s [options]\n", argv[0]);
            printf("Options:\n");
            printf("  -p PORT    Listen on PORT (default: %d)\n", DEFAULT_PORT);
            printf("  -d DIR     Store host key and logs in DIR\n");
            printf("  -h         Show this help\n");
            return 0;
        }
    }

    /* Setup signal handlers */
    signal(SIGINT, signal_handler);
    signal(SIGTERM, signal_handler);
    signal(SIGPIPE, SIG_IGN);

    /* Initialize subsystems */
    if (tnt_ensure_state_dir() < 0) {
        fprintf(stderr, "Failed to create state directory: %s\n", tnt_state_dir());
        return 1;
    }

    message_init();

    /* Create chat room */
    g_room = room_create();
    if (!g_room) {
        fprintf(stderr, "Failed to create chat room\n");
        return 1;
    }

    /* Initialize server */
    if (ssh_server_init(port) < 0) {
        fprintf(stderr, "Failed to initialize server\n");
        room_destroy(g_room);
        return 1;
    }

    /* Start server (blocking) */
    int ret = ssh_server_start(0);

    room_destroy(g_room);
    return ret;
}