btpd/btpd/main.c

#include <sys/types.h>
#include <sys/stat.h>

#include <assert.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <getopt.h>
#include <locale.h>
#include <pwd.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>

#include "btpd.h"

static void
writepid(int pidfd)
{
    FILE *fp = fdopen(dup(pidfd), "w");
    fprintf(fp, "%d", getpid());
    fclose(fp);
}

static char *
find_homedir(void)
{
    char *res = getenv("BTPD_HOME");
    if (res == NULL) {
        char *home = getenv("HOME");
        if (home == NULL) {
            struct passwd *pwent = getpwuid(getuid());
            if (pwent == NULL)
                errx(1, "Can't find my home directory.\n");
            home = pwent->pw_dir;
            endpwent();
        }
        asprintf(&res, "%s/.btpd", home);
    }
    return res;
}

static void
setup_daemon(const char *dir)
{
    int pidfd;

    if (dir == NULL)
        dir = find_homedir();

    btpd_dir = dir;

    if (mkdir(dir, 0777) == -1 && errno != EEXIST)
        err(1, "Couldn't create home '%s'", dir);

    if (chdir(dir) != 0)
        err(1, "Couldn't change working directory to '%s'", dir);

    if (mkdir("library", 0777) == -1 && errno != EEXIST)
        err(1, "Couldn't create library");

    pidfd = open("pid", O_CREAT|O_WRONLY|O_NONBLOCK|O_EXLOCK, 0666);
    if (pidfd == -1)
        err(1, "Couldn't open 'pid'");

    if (btpd_daemon) {
        if (daemon(1, 1) != 0)
            err(1, "Failed to daemonize");
        freopen("/dev/null", "r", stdin);
        if (freopen("log", "a", stdout) == NULL)
            err(1, "Couldn't open 'log'");
        dup2(fileno(stdout), fileno(stderr));
        setlinebuf(stdout);
        setlinebuf(stderr);
    }

    writepid(pidfd);
}

static void
usage(void)
{
    printf("Usage: btpd [options]\n"
        "\n"
        "Options:\n"
        "\n"
        "--bw-hz n\n"
        "\tRun the bandwidth limiter at n hz.\n"
        "\tDefault is 8 hz.\n"
        "\n"
        "--bw-in n\n"
        "\tLimit incoming BitTorrent traffic to n kB/s.\n"
        "\tDefault is 0 which means unlimited.\n"
        "\n"
        "--bw-out n\n"
        "\tLimit outgoing BitTorrent traffic to n kB/s.\n"
        "\tDefault is 0 which means unlimited.\n"
        "\n"
        "-d\n"
        "\tKeep the btpd process in the foregorund and log to std{out,err}.\n"
        "\tThis option is intended for debugging purposes.\n"
        "\n"
        "--ipc key\n"
        "\tThe same key must be used by the cli to talk to this\n"
        "\tbtpd instance. You shouldn't need to use this option.\n"
        "\n"
        "--logfile file\n"
        "\tLog to the given file. By default btpd logs to ./btpd.log.\n"
        "\n"
        "-p n, --port n\n"
        "\tListen at port n. Default is 6881.\n"
        "\n"
        "--help\n"
        "\tShow this help.\n"
        "\n");
    exit(1);
}

static int longval = 0;

static struct option longopts[] = {
    { "port",   required_argument,      NULL,           'p' },
    { "bw-in",  required_argument,      &longval,       1 },
    { "bw-out", required_argument,      &longval,       2 },
    { "help",   no_argument,            &longval,       5 },
    { NULL,     0,                      NULL,           0 }
};

int
main(int argc, char **argv)
{
    char *dir = NULL;

    setlocale(LC_ALL, "");

    for (;;) {
        switch (getopt_long(argc, argv, "dp:", longopts, NULL)) {
        case -1:
            goto args_done;
        case 'd':
            btpd_daemon = 0;
            break;
        case 'p':
            net_port = atoi(optarg);
            break;
        case 0:
            switch (longval) {
            case 1:
                net_bw_limit_in = atoi(optarg) * 1024;
                break;
            case 2:
                net_bw_limit_out = atoi(optarg) * 1024;
                break;
            default:
                usage();
            }
            break;
        case '?':
        default:
            usage();
        }
    }
args_done:
    argc -= optind;
    argv += optind;

    if (argc != 0)
        usage();

    setup_daemon(dir);

    event_init();

    btpd_init();

    event_dispatch();

    btpd_err("Unexpected exit from libevent.\n");

    return 1;
}