static SpawnResult spawn_via_launchd()

in watchman/main.cpp [411:557]

• 120 lines of code
• 10 McCabe index (conditional complexity)

static SpawnResult spawn_via_launchd() {
  char watchman_path[WATCHMAN_NAME_MAX];
  uint32_t size = sizeof(watchman_path);
  char plist_path[WATCHMAN_NAME_MAX];
  FILE* fp;
  struct passwd* pw;
  uid_t uid;

  close_random_fds();

  if (_NSGetExecutablePath(watchman_path, &size) == -1) {
    log(FATAL, "_NSGetExecutablePath: path too long; size ", size, "\n");
  }

  uid = getuid();
  pw = getpwuid(uid);
  if (!pw) {
    log(FATAL,
        "getpwuid(",
        uid,
        ") failed: ",
        folly::errnoStr(errno),
        ".  I don't know who you are\n");
  }

  snprintf(
      plist_path, sizeof(plist_path), "%s/Library/LaunchAgents", pw->pw_dir);
  // Best effort attempt to ensure that the agents dir exists.  We'll detect
  // and report the failure in the fopen call below.
  mkdir(plist_path, 0755);
  snprintf(
      plist_path,
      sizeof(plist_path),
      "%s/Library/LaunchAgents/com.github.facebook.watchman.plist",
      pw->pw_dir);

  if (access(plist_path, R_OK) == 0) {
    // Unload any that may already exist, as it is likely wrong

    ChildProcess unload_proc(
        {"/bin/launchctl", "unload", "-F", plist_path},
        ChildProcess::Options());
    unload_proc.wait();

    // Forcibly remove the plist.  In some cases it may have some attributes
    // set that prevent launchd from loading it.  This can happen where
    // the system was re-imaged or restored from a backup
    unlink(plist_path);
  }

  fp = fopen(plist_path, "w");
  if (!fp) {
    log(FATAL,
        "Failed to open ",
        plist_path,
        " for write: ",
        folly::errnoStr(errno),
        "\n");
  }

  compute_file_name(flags.pid_file, computeUserName(), "pid", "pidfile");

  const char* path_env =
      Configuration().getString("subprocess_path_env", getenv("PATH"));
  // If subprocess_path_env is not set and PATH is not in the environment,
  // set the path to the empty string.
  if (path_env == nullptr) {
    path_env = "";
  }

  auto plist_content = folly::to<std::string>(
      "<?xml version=\"1.0\" encoding=\"UTF-8\"?>\n"
      "<!DOCTYPE plist PUBLIC \"-//Apple//DTD PLIST 1.0//EN\" "
      "\"http://www.apple.com/DTDs/PropertyList-1.0.dtd\">\n"
      "<plist version=\"1.0\">\n"
      "<dict>\n"
      "    <key>Label</key>\n"
      "    <string>com.github.facebook.watchman</string>\n"
      "    <key>Disabled</key>\n"
      "    <false/>\n"
      "    <key>ProgramArguments</key>\n"
      "    <array>\n"
      "        <string>",
      watchman_path,
      "</string>\n"
      "        <string>--foreground</string>\n"
      "        <string>--logfile=",
      logging::log_name,
      "</string>\n"
      "        <string>--log-level=",
      logging::log_level,
      "</string>\n"
      // TODO: switch from `--sockname` to `--unix-listener-path`
      // after a grace period to allow for sane results if we
      // roll back to an earlier version
      "        <string>--sockname=",
      get_unix_sock_name(),
      "</string>\n"
      "        <string>--statefile=",
      flags.watchman_state_file,
      "</string>\n"
      "        <string>--pidfile=",
      flags.pid_file,
      "</string>\n"
      "    </array>\n"
      "    <key>KeepAlive</key>\n"
      "    <dict>\n"
      "        <key>Crashed</key>\n"
      "        <true/>\n"
      "    </dict>\n"
      "    <key>RunAtLoad</key>\n"
      "    <true/>\n"
      "    <key>EnvironmentVariables</key>\n"
      "    <dict>\n"
      "        <key>PATH</key>\n"
      "        <string>",
      path_env,
      "</string>\n"
      "    </dict>\n"
      "    <key>ProcessType</key>\n"
      "    <string>Interactive</string>\n"
      "    <key>Nice</key>\n"
      "    <integer>-5</integer>\n"
      "</dict>\n"
      "</plist>\n");
  fwrite(plist_content.data(), 1, plist_content.size(), fp);
  fclose(fp);
  // Don't rely on umask, ensure we have the correct perms
  chmod(plist_path, 0644);

  ChildProcess load_proc(
      {"/bin/launchctl", "load", "-F", plist_path}, ChildProcess::Options());
  auto res = load_proc.wait();

  if (WIFEXITED(res) && WEXITSTATUS(res) == 0) {
    return SpawnResult::Spawned;
  }

  // Most likely cause is "headless" operation with no GUI context
  if (WIFEXITED(res)) {
    logf(ERR, "launchctl: exited with status {}\n", WEXITSTATUS(res));
  } else if (WIFSIGNALED(res)) {
    logf(ERR, "launchctl: signaled with {}\n", WTERMSIG(res));
  }
  logf(ERR, "Falling back to daemonize\n");
  return run_service_as_daemon();
}