Waybar/src/modules/hyprland/backend.cpp

#include "modules/hyprland/backend.hpp"

#include <netdb.h>
#include <netinet/in.h>
#include <spdlog/spdlog.h>
#include <sys/socket.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/un.h>
#include <unistd.h>

#include <filesystem>
#include <string>
#include <thread>

namespace waybar::modules::hyprland {

std::filesystem::path IPC::socketFolder_;

std::filesystem::path IPC::getSocketFolder(const char* instanceSig) {
  static std::mutex folderMutex;
  std::unique_lock lock(folderMutex);

  // socket path, specified by EventManager of Hyprland
  if (!socketFolder_.empty()) {
    return socketFolder_;
  }

  const char* xdgRuntimeDirEnv = std::getenv("XDG_RUNTIME_DIR");
  std::filesystem::path xdgRuntimeDir;
  // Only set path if env variable is set
  if (xdgRuntimeDirEnv != nullptr) {
    xdgRuntimeDir = std::filesystem::path(xdgRuntimeDirEnv);
  }

  if (!xdgRuntimeDir.empty() && std::filesystem::exists(xdgRuntimeDir / "hypr")) {
    socketFolder_ = xdgRuntimeDir / "hypr";
  } else {
    spdlog::warn("$XDG_RUNTIME_DIR/hypr does not exist, falling back to /tmp/hypr");
    socketFolder_ = std::filesystem::path("/tmp") / "hypr";
  }

  socketFolder_ = socketFolder_ / instanceSig;
  return socketFolder_;
}

void IPC::startIPC() {
  // will start IPC and relay events to parseIPC

  std::thread([&]() {
    // check for hyprland
    const char* his = getenv("HYPRLAND_INSTANCE_SIGNATURE");

    if (his == nullptr) {
      spdlog::warn("Hyprland is not running, Hyprland IPC will not be available.");
      return;
    }

    if (!modulesReady) return;

    spdlog::info("Hyprland IPC starting");

    struct sockaddr_un addr;
    int socketfd = socket(AF_UNIX, SOCK_STREAM, 0);

    if (socketfd == -1) {
      spdlog::error("Hyprland IPC: socketfd failed");
      return;
    }

    addr.sun_family = AF_UNIX;

    auto socketPath = IPC::getSocketFolder(his) / ".socket2.sock";
    strncpy(addr.sun_path, socketPath.c_str(), sizeof(addr.sun_path) - 1);

    addr.sun_path[sizeof(addr.sun_path) - 1] = 0;

    int l = sizeof(struct sockaddr_un);

    if (connect(socketfd, (struct sockaddr*)&addr, l) == -1) {
      spdlog::error("Hyprland IPC: Unable to connect?");
      return;
    }

    auto* file = fdopen(socketfd, "r");

    while (true) {
      std::array<char, 1024> buffer;  // Hyprland socket2 events are max 1024 bytes

      auto* receivedCharPtr = fgets(buffer.data(), buffer.size(), file);

      if (receivedCharPtr == nullptr) {
        std::this_thread::sleep_for(std::chrono::milliseconds(1));
        continue;
      }

      std::string messageReceived(buffer.data());
      messageReceived = messageReceived.substr(0, messageReceived.find_first_of('\n'));
      spdlog::debug("hyprland IPC received {}", messageReceived);

      try {
        parseIPC(messageReceived);
      } catch (std::exception& e) {
        spdlog::warn("Failed to parse IPC message: {}, reason: {}", messageReceived, e.what());
      } catch (...) {
        throw;
      }

      std::this_thread::sleep_for(std::chrono::milliseconds(1));
    }
  }).detach();
}

void IPC::parseIPC(const std::string& ev) {
  std::string request = ev.substr(0, ev.find_first_of('>'));
  std::unique_lock lock(callbackMutex_);

  for (auto& [eventname, handler] : callbacks_) {
    if (eventname == request) {
      handler->onEvent(ev);
    }
  }
}

void IPC::registerForIPC(const std::string& ev, EventHandler* ev_handler) {
  if (ev_handler == nullptr) {
    return;
  }

  std::unique_lock lock(callbackMutex_);
  callbacks_.emplace_back(ev, ev_handler);
}

void IPC::unregisterForIPC(EventHandler* ev_handler) {
  if (ev_handler == nullptr) {
    return;
  }

  std::unique_lock lock(callbackMutex_);

  for (auto it = callbacks_.begin(); it != callbacks_.end();) {
    auto& [eventname, handler] = *it;
    if (handler == ev_handler) {
      callbacks_.erase(it++);
    } else {
      ++it;
    }
  }
}

std::string IPC::getSocket1Reply(const std::string& rq) {
  // basically hyprctl

  const auto serverSocket = socket(AF_UNIX, SOCK_STREAM, 0);

  if (serverSocket < 0) {
    throw std::runtime_error("Hyprland IPC: Couldn't open a socket (1)");
  }

  // get the instance signature
  auto* instanceSig = getenv("HYPRLAND_INSTANCE_SIGNATURE");

  if (instanceSig == nullptr) {
    throw std::runtime_error(
        "Hyprland IPC: HYPRLAND_INSTANCE_SIGNATURE was not set! (Is Hyprland running?)");
  }

  sockaddr_un serverAddress = {0};
  serverAddress.sun_family = AF_UNIX;

  std::string socketPath = IPC::getSocketFolder(instanceSig) / ".socket.sock";

  // Use snprintf to copy the socketPath string into serverAddress.sun_path
  if (snprintf(serverAddress.sun_path, sizeof(serverAddress.sun_path), "%s", socketPath.c_str()) <
      0) {
    throw std::runtime_error("Hyprland IPC: Couldn't copy socket path (6)");
  }

  if (connect(serverSocket, reinterpret_cast<sockaddr*>(&serverAddress), sizeof(serverAddress)) <
      0) {
    throw std::runtime_error("Hyprland IPC: Couldn't connect to " + socketPath + ". (3)");
  }

  auto sizeWritten = write(serverSocket, rq.c_str(), rq.length());

  if (sizeWritten < 0) {
    spdlog::error("Hyprland IPC: Couldn't write (4)");
    return "";
  }

  std::array<char, 8192> buffer = {0};
  std::string response;

  do {
    sizeWritten = read(serverSocket, buffer.data(), 8192);

    if (sizeWritten < 0) {
      spdlog::error("Hyprland IPC: Couldn't read (5)");
      close(serverSocket);
      return "";
    }
    response.append(buffer.data(), sizeWritten);
  } while (sizeWritten > 0);

  close(serverSocket);
  return response;
}

Json::Value IPC::getSocket1JsonReply(const std::string& rq) {
  std::string reply = getSocket1Reply("j/" + rq);

  if (reply.empty()) {
    return {};
  }

  return parser_.parse(reply);
}

}  // namespace waybar::modules::hyprland