vbx/src/input.c

#define _POSIX_C_SOURCE 200809L
#include "common/utils.h"
#include "common/ipc.h"
#include "common/log.h"
#include <time.h>
#include <errno.h>
#include <stdbool.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

#include <fcntl.h>
#include <getopt.h>
#include <libevdev/libevdev.h>
#include <libinput.h>
#include <libudev.h>
#include <poll.h>
#include <pthread.h>
#include <unistd.h>

#include "config.h"

#define MAX_BUFFER_LENGTH 512

enum error_code {
  NO_ERROR,
  UDEV_FAILED,
  LIBINPUT_FAILED,
  SEAT_FAILED,
  PERMISSION_FAILED
};

struct input_handler_data {
  struct udev *udev;
  struct libinput *libinput;
};

static void *handle_input(void *user_data) {
  struct input_handler_data *input_handler_data = user_data;
  char line[MAX_BUFFER_LENGTH];
  while (fgets(line, MAX_BUFFER_LENGTH, stdin) != NULL) {
    if (strcmp(line, "stop\n") == 0) {
      libinput_unref(input_handler_data->libinput);
      udev_unref(input_handler_data->udev);
      exit(EXIT_SUCCESS);
    }
  }
  return NULL;
}

static int open_restricted(const char *path, int flags, void *user_data) {
  (void)user_data;
  int fd = open(path, flags);
  if (fd < 0)
    LOG_PERROR("Failed to open path");
  return fd < 0 ? -errno : fd;
}

static void close_restricted(int fd, void *user_data) {
  (void)user_data;
  close(fd);
}

static const struct libinput_interface interface = {
    .open_restricted = open_restricted, .close_restricted = close_restricted};

static void send_event(uint32_t key_code, uint8_t is_pressed) {
  VbxEvent ev = { .key_code = key_code, .is_pressed = is_pressed };
  fwrite(&ev, sizeof(VbxEvent), 1, stdout);
}

static void send_key_event(struct libinput_event *event) {
  struct libinput_event_keyboard *keyboard =
      libinput_event_get_keyboard_event(event);
  uint32_t key_code = libinput_event_keyboard_get_key(keyboard);
  enum libinput_key_state state_code =
      libinput_event_keyboard_get_key_state(keyboard);
  send_event(key_code, state_code == LIBINPUT_KEY_STATE_PRESSED ? 1 : 0);
}

static void send_button_event(struct libinput_event *event) {
  struct libinput_event_pointer *pointer =
      libinput_event_get_pointer_event(event);
  uint32_t button_code = libinput_event_pointer_get_button(pointer);
  enum libinput_button_state state_code =
      libinput_event_pointer_get_button_state(pointer);
  send_event(button_code, state_code == LIBINPUT_BUTTON_STATE_PRESSED ? 1 : 0);
}

static int handle_events(struct libinput *libinput) {
  int result = -1;
  struct libinput_event *event;
  if (libinput_dispatch(libinput) < 0)
    return result;
    
  bool flushed = false;
  while ((event = libinput_get_event(libinput)) != NULL) {
    switch (libinput_event_get_type(event)) {
    case LIBINPUT_EVENT_KEYBOARD_KEY:
      send_key_event(event);
      flushed = true;
      break;
    case LIBINPUT_EVENT_POINTER_BUTTON:
      send_button_event(event);
      flushed = true;
      break;
    default:
      break;
    }
    libinput_event_destroy(event);
    result = 0;
  }
  
  if (flushed) {
    fflush(stdout);
  }
  return result;
}

static int run_mainloop(struct libinput *libinput) {
  struct pollfd fd;
  fd.fd = libinput_get_fd(libinput);
  fd.events = POLLIN;
  fd.revents = 0;
  if (handle_events(libinput) != 0) {
    LOG_ERROR("Expected device added events on startup but got none. Maybe you don't have the right permissions?");
    return -1;
  }
  while (1) {
    int pr = poll(&fd, 1, 10);
    if (pr < 0) {
      if (errno == EINTR)
        continue;
      LOG_PERROR("poll failed");
      return -1;
    }
    handle_events(libinput);
  }
  return 0;
}

void print_help(char *program_name) {
  printf("The backend of Show Me The Key.\n");
  printf("Version " PROJECT_VERSION ".\n");
  printf("Usage: %s [OPTION…]\n", program_name);
  printf("Options:\n");
  printf("\t-h, --help\tDisplay help then exit.\n");
  printf("\t-v, --version\tDisplay version then exit.\n");
  printf("Warning: This is the backend and is not designed to run by users. "
         "You should run the frontend of Show Me The Key, and the frontend "
         "will run this.\n");
}

int is_daemon = 0;

int main(int argc, char *argv[]) {
  setvbuf(stdout, NULL, _IOLBF, 0);
  const struct option long_options[] = {{"version", no_argument, 0, 'v'},
                                        {"help", no_argument, 0, 'h'},
                                        {NULL, 0, NULL, 0}};
  int option_index = 0;
  int opt = 0;
  while ((opt = getopt_long(argc, argv, "vh", long_options, &option_index)) !=
         -1) {
    switch (opt) {
    case 0:
      break;
    case 'v':
      printf(PROJECT_VERSION "\n");
      return 0;
    case 'h':
      print_help(argv[0]);
      return 0;
    case '?':
      break;
    default:
      LOG_ERROR("Invalid option `-%c`.", opt);
      break;
    }
  }
  struct udev *udev = udev_new();
  if (udev == NULL) {
    LOG_ERROR("Failed to initialize udev.");
    return 1;
  }
  struct libinput *libinput =
      libinput_udev_create_context(&interface, NULL, udev);
  if (!libinput) {
    LOG_ERROR("Failed to initialize libinput from udev.");
    return 1;
  }
  if (libinput_udev_assign_seat(libinput, "seat0") != 0) {
    LOG_ERROR("Failed to set seat.");
    libinput_unref(libinput);
    udev_unref(udev);
    return SEAT_FAILED;
  }
  pthread_t input_handler;
  struct input_handler_data input_handler_data = {udev, libinput};
  if (pthread_create(&input_handler, NULL, handle_input, &input_handler_data) !=
      0) {
    LOG_ERROR("Failed to create input handler thread.");
  } else {
    pthread_detach(input_handler);
  }
  if (run_mainloop(libinput) < 0)
    return PERMISSION_FAILED;
  libinput_unref(libinput);
  udev_unref(udev);
  return NO_ERROR;
}