Have Meson orchestrate the whole build rather than stack.

As a part of this, I changed the file layout to:

rt/ - the Montis runtime
plug/ - the Montis plugin
wlroots/ - wlroots

2 files changed, 1332 insertions, 0 deletions

diff --git a/rt/src/plugin.c b/rt/src/plugin.c
new file mode 100644
index 0000000..37a6dd3
--- /dev/null
+++ b/rt/src/plugin.c
@@ -0,0 +1,266 @@
+#include "plugin.h"
+#include "foreign_intf.h"
+#include "wl.h"
+
+#include <sys/stat.h>
+#include <unistd.h>
+#include <ctype.h>
+#include <dlfcn.h>
+#include <pthread.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+
+/* Utility function for showing the marshalled states as hex code */
+static void shx(uint8_t *state, uint32_t sz)
+{
+  uint32_t i = 0;
+  while (i < sz) {
+    for (int j = 0; j < 16; ++j) {
+      if (i < sz) {
+        printf("%02x ", (unsigned int)state[i]);
+      }
+      else {
+        printf("   ");
+      }
+      ++i;
+    }
+
+    i -= 16;
+
+    printf("   ");
+
+    for (int j = 0; j < 16; ++j) {
+      if (i < sz) {
+        if (isprint(state[i]) && !isspace(state[i])) {
+          printf("%c", state[i]);
+        }
+        else {
+          printf(".");
+        }
+      }
+      else {
+        printf(" ");
+      }
+      ++i;
+    }
+    printf("\n");
+  }
+}
+
+int load_plugin_from_dl_(dlhandle_t dl, plugin_t *plug);
+
+static void lock(plugin_t *plugin) { pthread_mutex_lock(&plugin->lock); };
+
+static void unlock(plugin_t *plugin) { pthread_mutex_unlock(&plugin->lock); };
+
+static int plugin_hot_reload_same_state_action_(plugin_t *plugin, void *ignore)
+{
+  return plugin_hot_reload_same_state(plugin);
+}
+
+void do_request_hot_reload(void *plugv)
+{
+  plugin_t *plugin = plugv;
+
+  size_t n = plugin->n_requested_actions++;
+  if (n < 8) {
+    plugin->requested_actions[n].action = plugin_hot_reload_same_state_action_;
+    plugin->requested_actions[n].arg_dtor = NULL;
+  }
+}
+
+static int plugin_do_log(plugin_t *plugin, void *chrs)
+{
+  char *str = chrs;
+  puts(str);
+  return 0;
+}
+
+void do_request_log(void *plugv, const char *str)
+{
+  plugin_t *plugin = plugv;
+
+  size_t n = plugin->n_requested_actions++;
+  if (n < 8) {
+    plugin->requested_actions[n].action = plugin_do_log;
+    plugin->requested_actions[n].str_arg = strdup(str);
+    plugin->requested_actions[n].arg_dtor = free;
+  }
+}
+
+static int plugin_do_exit(void *plugv, int ec)
+{
+  exit(ec);
+  return 0;
+}
+
+void do_request_exit(void *plugv, int ec)
+{
+  plugin_t *plugin = plugv;
+
+  size_t n = plugin->n_requested_actions++;
+  if (n < 8) {
+    plugin->requested_actions[n].action =
+        (int (*)(plugin_t *, void *))plugin_do_exit;
+    plugin->requested_actions[n].int_arg = ec;
+    plugin->requested_actions[n].arg_dtor = NULL;
+  }
+}
+
+static void* plugin_get_seat(void* ctx) {
+  struct montis_server* server = wl_container_of(ctx, server, plugin);
+  return server->seat;
+}
+
+static int load_plugin_from_file_(int argc, char **argv, const char *filename,
+                                  plugin_t *plugin)
+{
+  dlhandle_t lib = dlopen(filename, RTLD_LAZY);
+  int ec = 0;
+
+  if (!lib) {
+    fprintf(stderr, "Failed to open library: %s: %s\n", filename, dlerror());
+    ec = 1;
+    goto end;
+  }
+
+  printf("Loading file.\n");
+  ec = load_plugin_from_dl_(lib, plugin);
+
+  if (ec) {
+    goto end;
+  }
+
+  strncpy(plugin->filename, filename, sizeof(plugin->filename));
+  plugin->argc = argc;
+  plugin->argv = argv;
+
+  plugin->foreign_intf.ctx = plugin;
+  plugin->foreign_intf.request_hot_reload = do_request_hot_reload;
+  plugin->foreign_intf.do_log = do_request_log;
+  plugin->foreign_intf.request_exit = do_request_exit;
+  plugin->foreign_intf.get_seat = plugin_get_seat;
+
+  plugin->plugin_load(plugin->argc, plugin->argv, &plugin->foreign_intf);
+end:
+  return ec;
+}
+
+static void maybe_run_metaload(int argc, char **argv, plugin_t *plugin)
+{
+  static char *loaded_plugins[12];
+  int i;
+  for (i = 0; i < 12 && loaded_plugins[i]; ++i) {
+    if (strcmp(loaded_plugins[i], plugin->plugin_name) == 0) {
+      return; // Plugin is already loaded
+    }
+  }
+  loaded_plugins[i] = strdup(plugin->plugin_name);
+
+  printf("First time loading %s, running metaload.\n", plugin->plugin_name);
+  if (plugin->plugin_metaload) {
+    plugin->plugin_metaload(argc, argv);
+  }
+}
+
+int load_plugin_from_file(int argc, char **argv, const char *filename,
+                          plugin_t *plugin)
+{
+  memset(plugin, 0, sizeof(*plugin));
+
+  pthread_mutexattr_t attr;
+  if (pthread_mutexattr_init(&attr)) {
+    perror("pthread_mutexattr_init");
+    return 1;
+  }
+
+  if (pthread_mutexattr_settype(&attr, PTHREAD_MUTEX_RECURSIVE)) {
+    perror("pthread_mutexattr_settype");
+    return 1;
+  }
+
+  if (pthread_mutex_init(&plugin->lock, &attr)) {
+    pthread_mutexattr_destroy(&attr);
+    perror("pthread_mutexattr_init");
+    return 1;
+  }
+  pthread_mutexattr_destroy(&attr);
+  int rc = load_plugin_from_file_(argc, argv, filename, plugin);
+
+  if (rc == 0) {
+    maybe_run_metaload(argc, argv, plugin);
+  }
+
+  return rc;
+}
+
+int plugin_hot_reload_same_state(plugin_t *plugin)
+{
+  char filename_cpy[PATH_MAX];
+  strncpy(filename_cpy, plugin->filename, sizeof(filename_cpy));
+  return plugin_hot_reload(plugin->argc, plugin->argv, filename_cpy, plugin);
+}
+
+int plugin_hot_reload(int argc, char **argv, const char *filepath,
+                      plugin_t *plugin)
+{
+  int ec = 0;
+  uint32_t sz = 0;
+  uint8_t *marshalled_state = NULL;
+
+  printf("Hot Reloading %s\n", plugin->plugin_name);
+  lock(plugin);
+
+  printf("Marshalling state ...\n");
+  marshalled_state = plugin->plugin_marshal_state(plugin->state, &sz);
+
+  printf("Calling teardown ...\n");
+  plugin->plugin_teardown(plugin->state);
+
+  printf("State Marshalled:\n");
+  shx(marshalled_state, sz);
+
+  printf("Unloading old library handle.\n");
+  if (dlclose(plugin->library_handle)) {
+    printf("Could not close library handle: %s\n", dlerror());
+  }
+
+  if ((ec = load_plugin_from_file_(argc, argv, filepath, plugin))) {
+    goto fail;
+  }
+
+  printf("Hot starting plugin ...\n");
+  plugin->state = plugin->plugin_hot_start(marshalled_state, sz);
+
+fail:
+  free(marshalled_state);
+  unlock(plugin);
+  return ec;
+}
+
+void plugin_run_requested_actions(plugin_t *plugin)
+{
+  lock(plugin);
+  requested_action_t requested_actions[MAX_QUEUED_ACTIONS];
+  size_t n_requested_actions = plugin->n_requested_actions;
+  memcpy(&requested_actions, plugin->requested_actions,
+         sizeof(requested_actions));
+  plugin->n_requested_actions = 0;
+  unlock(plugin);
+
+  size_t i;
+  for (i = 0; i < n_requested_actions; ++i) {
+    requested_actions[i].action(plugin, requested_actions[i].str_arg);
+    if (requested_actions[i].arg_dtor) {
+      requested_actions[i].arg_dtor(requested_actions[i].ptr_arg);
+    }
+  }
+}
+
+void plugin_cold_start(plugin_t *plugin)
+{
+  lock(plugin);
+  plugin->state = plugin->plugin_cold_start();
+  unlock(plugin);
+}
diff --git a/rt/src/wl.c b/rt/src/wl.c
new file mode 100644
index 0000000..261e082
--- /dev/null
+++ b/rt/src/wl.c
@@ -0,0 +1,1066 @@
+#define _POSIX_C_SOURCE 200112L
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <sys/time.h>
+#include <time.h>
+
+#include <wl.h>
+
+#include "xdg-decoration-unstable-v1-client-protocol.h"
+
+// This macro is responsible for calling a handler on a plugin. This macro will
+// acquire the plugin's lock, call the member with the arguments and update the
+// state.
+//
+// This only works on function which have the format:
+//
+// opqst_t function(args ..., opqst_t state);
+//
+// Note that the state parameter is omitted from this macro.
+#define plugin_call_update_state(plugin, member, ...)                          \
+  do {                                                                         \
+    plugin_t *pl__ = &(plugin);                                                \
+    pthread_mutex_lock(&pl__->lock);                                           \
+    pl__->state = pl__->member(__VA_ARGS__, pl__->state);                      \
+    pthread_mutex_unlock(&pl__->lock);                                         \
+    plugin_run_requested_actions(pl__);                                        \
+  } while (0)
+
+static void focus_toplevel(struct montis_toplevel *toplevel,
+                           struct wlr_surface *surface)
+{
+  /* Note: this function only deals with keyboard focus. */
+  if (toplevel == NULL) {
+    return;
+  }
+  struct montis_server *server = toplevel->server;
+  struct wlr_seat *seat = server->seat;
+  struct wlr_surface *prev_surface = seat->keyboard_state.focused_surface;
+  if (prev_surface == surface) {
+    /* Don't re-focus an already focused surface. */
+    return;
+  }
+  if (prev_surface) {
+    /*
+     * Deactivate the previously focused surface. This lets the client know
+     * it no longer has focus and the client will repaint accordingly, e.g.
+     * stop displaying a caret.
+     */
+    struct wlr_xdg_toplevel *prev_toplevel =
+        wlr_xdg_toplevel_try_from_wlr_surface(prev_surface);
+    if (prev_toplevel != NULL) {
+      wlr_xdg_toplevel_set_activated(prev_toplevel, false);
+    }
+  }
+  struct wlr_keyboard *keyboard = wlr_seat_get_keyboard(seat);
+  /* Move the toplevel to the front */
+  wlr_scene_node_raise_to_top(&toplevel->scene_tree->node);
+  wl_list_remove(&toplevel->link);
+  wl_list_insert(&server->toplevels, &toplevel->link);
+  /* Activate the new surface */
+  wlr_xdg_toplevel_set_activated(toplevel->xdg_toplevel, true);
+  /*
+   * Tell the seat to have the keyboard enter this surface. wlroots will keep
+   * track of this and automatically send key events to the appropriate
+   * clients without additional work on your part.
+   */
+  if (keyboard != NULL) {
+    wlr_seat_keyboard_notify_enter(seat, toplevel->xdg_toplevel->base->surface,
+                                   keyboard->keycodes, keyboard->num_keycodes,
+                                   &keyboard->modifiers);
+  }
+}
+
+static void keyboard_handle_modifiers(struct wl_listener *listener, void *data)
+{
+  /* This event is raised when a modifier key, such as shift or alt, is
+   * pressed. We simply communicate this to the client. */
+  struct montis_keyboard *keyboard =
+      wl_container_of(listener, keyboard, modifiers);
+  /*
+   * A seat can only have one keyboard, but this is a limitation of the
+   * Wayland protocol - not wlroots. We assign all connected keyboards to the
+   * same seat. You can swap out the underlying wlr_keyboard like this and
+   * wlr_seat handles this transparently.
+   */
+  wlr_seat_set_keyboard(keyboard->server->seat, keyboard->wlr_keyboard);
+  /* Send modifiers to the client. */
+  wlr_seat_keyboard_notify_modifiers(keyboard->server->seat,
+                                     &keyboard->wlr_keyboard->modifiers);
+}
+
+static void keyboard_handle_key(struct wl_listener *listener, void *data)
+{
+  /* This event is raised when a key is pressed or released. */
+  struct montis_keyboard *keyboard = wl_container_of(listener, keyboard, key);
+  struct montis_server *server = keyboard->server;
+  struct wlr_keyboard_key_event *event = data;
+  struct wlr_seat *seat = server->seat;
+
+  /* Translate libinput keycode -> xkbcommon */
+  uint32_t keycode = event->keycode + 8;
+  /* Get a list of keysyms based on the keymap for this keyboard */
+  const xkb_keysym_t *syms;
+  int nsyms =
+      xkb_state_key_get_syms(keyboard->wlr_keyboard->xkb_state, keycode, &syms);
+
+  int handled = false;
+  uint32_t modifiers = wlr_keyboard_get_modifiers(keyboard->wlr_keyboard);
+  uint32_t codepoint;
+  int ec;
+
+  if (nsyms > 0 && syms[0] >= XKB_KEY_XF86Switch_VT_1 &&
+      syms[0] <= XKB_KEY_XF86Switch_VT_12) {
+    /* Escape-hatch to change sessions. These should always be available key
+     * bindings regardless of what the plugin dictates. This allows an escape
+     * hatch to edit the plugin in a different vterm and then use the escape
+     * hatch below to hot-restart the plugin if things get borked. */
+    if (event->state == WL_KEYBOARD_KEY_STATE_PRESSED) {
+      wlr_session_change_vt(server->session,
+                            syms[0] - XKB_KEY_XF86Switch_VT_1 + 1);
+    }
+  }
+  else if (modifiers ==
+               (WLR_MODIFIER_SHIFT | WLR_MODIFIER_CTRL | WLR_MODIFIER_ALT) &&
+           nsyms > 0 && syms[0] == XKB_KEY_Escape) {
+    /* Escape-hatch to hot-reload the plugin in case the plugin got borked and
+     * stops accepting keybindings. Ctrl+Shift+Alt+Escape will always reload the
+     * plugin.*/
+    if (event->state == WL_KEYBOARD_KEY_STATE_PRESSED) {
+      if ((ec = plugin_hot_reload_same_state(&server->plugin)) != 0) {
+        fprintf(stderr, "Failed to hot reload plugin");
+        exit(1);
+      }
+    }
+  }
+  else {
+    /* Pass the information along to the plugin for the plugin to handle. The
+     * plugin will return via 'handled' whether or not the key event was handled
+     * or not. */
+    if (nsyms > 0) {
+      codepoint =
+          xkb_state_key_get_utf32(keyboard->wlr_keyboard->xkb_state, keycode);
+      plugin_call_update_state(server->plugin, plugin_handle_keybinding,
+                               keyboard->wlr_keyboard, event, modifiers,
+                               syms[0], codepoint, &handled);
+    }
+  }
+}
+
+static void keyboard_handle_destroy(struct wl_listener *listener, void *data)
+{
+  /* This event is raised by the keyboard base wlr_input_device to signal
+   * the destruction of the wlr_keyboard. It will no longer receive events
+   * and should be destroyed.
+   */
+  struct montis_keyboard *keyboard =
+      wl_container_of(listener, keyboard, destroy);
+  wl_list_remove(&keyboard->modifiers.link);
+  wl_list_remove(&keyboard->key.link);
+  wl_list_remove(&keyboard->destroy.link);
+  wl_list_remove(&keyboard->link);
+  free(keyboard);
+}
+
+static void server_new_keyboard(struct montis_server *server,
+                                struct wlr_input_device *device)
+{
+  struct wlr_keyboard *wlr_keyboard = wlr_keyboard_from_input_device(device);
+
+  struct montis_keyboard *keyboard = calloc(1, sizeof(*keyboard));
+  keyboard->server = server;
+  keyboard->wlr_keyboard = wlr_keyboard;
+
+  struct xkb_rule_names names = (struct xkb_rule_names){0};
+  names.layout = "jr";
+  names.variant = "jdvprk";
+  names.options = "numpad:mac";
+
+  /* We need to prepare an XKB keymap and assign it to the keyboard. This
+   * assumes the defaults (e.g. layout = "us"). */
+  struct xkb_context *context = xkb_context_new(XKB_CONTEXT_NO_FLAGS);
+  struct xkb_keymap *keymap =
+      xkb_keymap_new_from_names(context, &names, XKB_KEYMAP_COMPILE_NO_FLAGS);
+
+  if (!keymap) {
+    fprintf(stderr, "Unable to read keymap.\n");
+    exit(1);
+  }
+
+  wlr_keyboard_set_keymap(wlr_keyboard, keymap);
+  xkb_keymap_unref(keymap);
+  xkb_context_unref(context);
+  wlr_keyboard_set_repeat_info(wlr_keyboard, 25, 600);
+
+  /* Here we set up listeners for keyboard events. */
+  keyboard->modifiers.notify = keyboard_handle_modifiers;
+  wl_signal_add(&wlr_keyboard->events.modifiers, &keyboard->modifiers);
+  keyboard->key.notify = keyboard_handle_key;
+  wl_signal_add(&wlr_keyboard->events.key, &keyboard->key);
+  keyboard->destroy.notify = keyboard_handle_destroy;
+  wl_signal_add(&device->events.destroy, &keyboard->destroy);
+
+  wlr_seat_set_keyboard(server->seat, keyboard->wlr_keyboard);
+
+  /* And add the keyboard to our list of keyboards */
+  wl_list_insert(&server->keyboards, &keyboard->link);
+}
+
+static void server_new_pointer(struct montis_server *server,
+                               struct wlr_input_device *device)
+{
+  /* We don't do anything special with pointers. All of our pointer handling
+   * is proxied through wlr_cursor. On another compositor, you might take this
+   * opportunity to do libinput configuration on the device to set
+   * acceleration, etc. */
+  wlr_cursor_attach_input_device(server->cursor, device);
+}
+
+static void server_new_input(struct wl_listener *listener, void *data)
+{
+  /* This event is raised by the backend when a new input device becomes
+   * available. */
+  struct montis_server *server = wl_container_of(listener, server, new_input);
+  struct wlr_input_device *device = data;
+  switch (device->type) {
+  case WLR_INPUT_DEVICE_KEYBOARD:
+    server_new_keyboard(server, device);
+    break;
+  case WLR_INPUT_DEVICE_POINTER:
+    server_new_pointer(server, device);
+    break;
+  default:
+    break;
+  }
+  /* We need to let the wlr_seat know what our capabilities are, which is
+   * communiciated to the client. In TinyWL we always have a cursor, even if
+   * there are no pointer devices, so we always include that capability. */
+  uint32_t caps = WL_SEAT_CAPABILITY_POINTER;
+  if (!wl_list_empty(&server->keyboards)) {
+    caps |= WL_SEAT_CAPABILITY_KEYBOARD;
+  }
+  wlr_seat_set_capabilities(server->seat, caps);
+}
+
+static void seat_request_cursor(struct wl_listener *listener, void *data)
+{
+  struct montis_server *server =
+      wl_container_of(listener, server, request_cursor);
+  /* This event is raised by the seat when a client provides a cursor image */
+  struct wlr_seat_pointer_request_set_cursor_event *event = data;
+  struct wlr_seat_client *focused_client =
+      server->seat->pointer_state.focused_client;
+  /* This can be sent by any client, so we check to make sure this one is
+   * actually has pointer focus first. */
+  if (focused_client == event->seat_client) {
+    /* Once we've vetted the client, we can tell the cursor to use the
+     * provided surface as the cursor image. It will set the hardware cursor
+     * on the output that it's currently on and continue to do so as the
+     * cursor moves between outputs. */
+    wlr_cursor_set_surface(server->cursor, event->surface, event->hotspot_x,
+                           event->hotspot_y);
+  }
+}
+
+static void seat_request_set_selection(struct wl_listener *listener, void *data)
+{
+  /* This event is raised by the seat when a client wants to set the selection,
+   * usually when the user copies something. wlroots allows compositors to
+   * ignore such requests if they so choose, but in montis we always honor
+   */
+  struct montis_server *server =
+      wl_container_of(listener, server, request_set_selection);
+  struct wlr_seat_request_set_selection_event *event = data;
+  wlr_seat_set_selection(server->seat, event->source, event->serial);
+}
+
+static struct montis_toplevel *desktop_toplevel_at(struct montis_server *server,
+                                                   double lx, double ly,
+                                                   struct wlr_surface **surface,
+                                                   double *sx, double *sy)
+{
+  /* This returns the topmost node in the scene at the given layout coords.
+   * We only care about surface nodes as we are specifically looking for a
+   * surface in the surface tree of a montis_toplevel. */
+  struct wlr_scene_node *node =
+      wlr_scene_node_at(&server->scene->tree.node, lx, ly, sx, sy);
+  if (node == NULL || node->type != WLR_SCENE_NODE_BUFFER) {
+    return NULL;
+  }
+  struct wlr_scene_buffer *scene_buffer = wlr_scene_buffer_from_node(node);
+  struct wlr_scene_surface *scene_surface =
+      wlr_scene_surface_try_from_buffer(scene_buffer);
+  if (!scene_surface) {
+    return NULL;
+  }
+
+  *surface = scene_surface->surface;
+  /* Find the node corresponding to the montis_toplevel at the root of this
+   * surface tree, it is the only one for which we set the data field. */
+  struct wlr_scene_tree *tree = node->parent;
+  while (tree != NULL && tree->node.data == NULL) {
+    tree = tree->node.parent;
+  }
+  return tree->node.data;
+}
+
+static void reset_cursor_mode(struct montis_server *server)
+{
+  /* Reset the cursor mode to passthrough. */
+  server->cursor_mode = TINYWL_CURSOR_PASSTHROUGH;
+  server->grabbed_toplevel = NULL;
+}
+
+static void process_cursor_move(struct montis_server *server, uint32_t time)
+{
+  /* Move the grabbed toplevel to the new position. */
+  struct montis_toplevel *toplevel = server->grabbed_toplevel;
+  wlr_scene_node_set_position(&toplevel->scene_tree->node,
+                              server->cursor->x - server->grab_x,
+                              server->cursor->y - server->grab_y);
+}
+
+static void process_cursor_resize(struct montis_server *server, uint32_t time)
+{
+  /*
+   * Resizing the grabbed toplevel can be a little bit complicated, because we
+   * could be resizing from any corner or edge. This not only resizes the
+   * toplevel on one or two axes, but can also move the toplevel if you resize
+   * from the top or left edges (or top-left corner).
+   *
+   * Note that some shortcuts are taken here. In a more fleshed-out
+   * compositor, you'd wait for the client to prepare a buffer at the new
+   * size, then commit any movement that was prepared.
+   */
+  struct montis_toplevel *toplevel = server->grabbed_toplevel;
+  double border_x = server->cursor->x - server->grab_x;
+  double border_y = server->cursor->y - server->grab_y;
+  int new_left = server->grab_geobox.x;
+  int new_right = server->grab_geobox.x + server->grab_geobox.width;
+  int new_top = server->grab_geobox.y;
+  int new_bottom = server->grab_geobox.y + server->grab_geobox.height;
+
+  if (server->resize_edges & WLR_EDGE_TOP) {
+    new_top = border_y;
+    if (new_top >= new_bottom) {
+      new_top = new_bottom - 1;
+    }
+  }
+  else if (server->resize_edges & WLR_EDGE_BOTTOM) {
+    new_bottom = border_y;
+    if (new_bottom <= new_top) {
+      new_bottom = new_top + 1;
+    }
+  }
+  if (server->resize_edges & WLR_EDGE_LEFT) {
+    new_left = border_x;
+    if (new_left >= new_right) {
+      new_left = new_right - 1;
+    }
+  }
+  else if (server->resize_edges & WLR_EDGE_RIGHT) {
+    new_right = border_x;
+    if (new_right <= new_left) {
+      new_right = new_left + 1;
+    }
+  }
+
+  struct wlr_box geo_box;
+  wlr_xdg_surface_get_geometry(toplevel->xdg_toplevel->base, &geo_box);
+  wlr_scene_node_set_position(&toplevel->scene_tree->node, new_left - geo_box.x,
+                              new_top - geo_box.y);
+
+  int new_width = new_right - new_left;
+  int new_height = new_bottom - new_top;
+  wlr_xdg_toplevel_set_size(toplevel->xdg_toplevel, new_width, new_height);
+}
+
+static void process_cursor_motion(struct montis_server *server, uint32_t time)
+{
+  /* If the mode is non-passthrough, delegate to those functions. */
+  if (server->cursor_mode == TINYWL_CURSOR_MOVE) {
+    process_cursor_move(server, time);
+    return;
+  }
+  else if (server->cursor_mode == TINYWL_CURSOR_RESIZE) {
+    process_cursor_resize(server, time);
+    return;
+  }
+
+  /* Otherwise, find the toplevel under the pointer and send the event along. */
+  double sx, sy;
+  struct wlr_seat *seat = server->seat;
+  struct wlr_surface *surface = NULL;
+  struct montis_toplevel *toplevel = desktop_toplevel_at(
+      server, server->cursor->x, server->cursor->y, &surface, &sx, &sy);
+  if (!toplevel) {
+    /* If there's no toplevel under the cursor, set the cursor image to a
+     * default. This is what makes the cursor image appear when you move it
+     * around the screen, not over any toplevels. */
+    wlr_cursor_set_xcursor(server->cursor, server->cursor_mgr, "default");
+  }
+  if (surface) {
+    /*
+     * Send pointer enter and motion events.
+     *
+     * The enter event gives the surface "pointer focus", which is distinct
+     * from keyboard focus. You get pointer focus by moving the pointer over
+     * a window.
+     *
+     * Note that wlroots will avoid sending duplicate enter/motion events if
+     * the surface has already has pointer focus or if the client is already
+     * aware of the coordinates passed.
+     */
+    wlr_seat_pointer_notify_enter(seat, surface, sx, sy);
+    wlr_seat_pointer_notify_motion(seat, time, sx, sy);
+  }
+  else {
+    /* Clear pointer focus so future button events and such are not sent to
+     * the last client to have the cursor over it. */
+    wlr_seat_pointer_clear_focus(seat);
+  }
+}
+
+static void server_cursor_motion(struct wl_listener *listener, void *data)
+{
+  /* This event is forwarded by the cursor when a pointer emits a _relative_
+   * pointer motion event (i.e. a delta) */
+  struct montis_server *server =
+      wl_container_of(listener, server, cursor_motion);
+  struct wlr_pointer_motion_event *event = data;
+  /* The cursor doesn't move unless we tell it to. The cursor automatically
+   * handles constraining the motion to the output layout, as well as any
+   * special configuration applied for the specific input device which
+   * generated the event. You can pass NULL for the device if you want to move
+   * the cursor around without any input. */
+  wlr_cursor_move(server->cursor, &event->pointer->base, event->delta_x,
+                  event->delta_y);
+  process_cursor_motion(server, event->time_msec);
+}
+
+static void server_cursor_motion_absolute(struct wl_listener *listener,
+                                          void *data)
+{
+  /* This event is forwarded by the cursor when a pointer emits an _absolute_
+   * motion event, from 0..1 on each axis. This happens, for example, when
+   * wlroots is running under a Wayland window rather than KMS+DRM, and you
+   * move the mouse over the window. You could enter the window from any edge,
+   * so we have to warp the mouse there. There is also some hardware which
+   * emits these events. */
+  struct montis_server *server =
+      wl_container_of(listener, server, cursor_motion_absolute);
+  struct wlr_pointer_motion_absolute_event *event = data;
+  wlr_cursor_warp_absolute(server->cursor, &event->pointer->base, event->x,
+                           event->y);
+  process_cursor_motion(server, event->time_msec);
+}
+
+static void server_cursor_button(struct wl_listener *listener, void *data)
+{
+  /* This event is forwarded by the cursor when a pointer emits a button
+   * event. */
+  struct montis_server *server =
+      wl_container_of(listener, server, cursor_button);
+  struct wlr_pointer_button_event *event = data;
+  struct wlr_seat *seat = server->seat;
+  struct wlr_keyboard *keyboard = wlr_seat_get_keyboard(seat);
+  uint32_t modifiers = wlr_keyboard_get_modifiers(keyboard);
+
+  plugin_call_update_state(server->plugin, plugin_handle_button, event,
+                           modifiers);
+
+  /* Notify the client with pointer focus that a button press has occurred */
+  // wlr_seat_pointer_notify_button(server->seat, event->time_msec,
+  // event->button,
+  //                                event->state);
+  // double sx, sy;
+  // struct wlr_surface *surface = NULL;
+  // struct montis_toplevel *toplevel = desktop_toplevel_at(
+  //     server, server->cursor->x, server->cursor->y, &surface, &sx, &sy);
+  // if (event->state == WLR_BUTTON_RELEASED) {
+  //   /* If you released any buttons, we exit interactive move/resize mode. */
+  //   reset_cursor_mode(server);
+  // }
+  // else {
+  //   /* Focus that client if the button was _pressed_ */
+  //   focus_toplevel(toplevel, surface);
+  // }
+}
+
+static void server_cursor_axis(struct wl_listener *listener, void *data)
+{
+  /* This event is forwarded by the cursor when a pointer emits an axis event,
+   * for example when you move the scroll wheel. */
+  struct montis_server *server = wl_container_of(listener, server, cursor_axis);
+  struct wlr_pointer_axis_event *event = data;
+  /* Notify the client with pointer focus of the axis event. */
+  wlr_seat_pointer_notify_axis(
+      server->seat, event->time_msec, event->orientation, event->delta,
+      event->delta_discrete, event->source, event->relative_direction);
+}
+
+static void server_cursor_frame(struct wl_listener *listener, void *data)
+{
+  /* This event is forwarded by the cursor when a pointer emits an frame
+   * event. Frame events are sent after regular pointer events to group
+   * multiple events together. For instance, two axis events may happen at the
+   * same time, in which case a frame event won't be sent in between. */
+  struct montis_server *server =
+      wl_container_of(listener, server, cursor_frame);
+  /* Notify the client with pointer focus of the frame event. */
+  wlr_seat_pointer_notify_frame(server->seat);
+}
+
+static void output_frame(struct wl_listener *listener, void *data)
+{
+  /* This function is called every time an output is ready to display a frame,
+   * generally at the output's refresh rate (e.g. 60Hz). */
+  struct montis_output *output = wl_container_of(listener, output, frame);
+  struct wlr_scene *scene = output->server->scene;
+
+  struct wlr_scene_output *scene_output =
+      wlr_scene_get_scene_output(scene, output->wlr_output);
+
+  /* Render the scene if needed and commit the output */
+  wlr_scene_output_commit(scene_output, NULL);
+
+  struct timespec now;
+  clock_gettime(CLOCK_MONOTONIC, &now);
+  wlr_scene_output_send_frame_done(scene_output, &now);
+}
+
+static void output_request_state(struct wl_listener *listener, void *data)
+{
+  /* This function is called when the backend requests a new state for
+   * the output. For example, Wayland and X11 backends request a new mode
+   * when the output window is resized. */
+  struct montis_output *output =
+      wl_container_of(listener, output, request_state);
+  const struct wlr_output_event_request_state *event = data;
+  wlr_output_commit_state(output->wlr_output, event->state);
+}
+
+static void output_destroy(struct wl_listener *listener, void *data)
+{
+  struct montis_output *output = wl_container_of(listener, output, destroy);
+
+  wl_list_remove(&output->frame.link);
+  wl_list_remove(&output->request_state.link);
+  wl_list_remove(&output->destroy.link);
+  wl_list_remove(&output->link);
+  free(output);
+}
+
+static void server_new_output(struct wl_listener *listener, void *data)
+{
+  /* This event is raised by the backend when a new output (aka a display or
+   * monitor) becomes available. */
+  struct montis_server *server = wl_container_of(listener, server, new_output);
+  struct wlr_output *wlr_output = data;
+
+  /* Configures the output created by the backend to use our allocator
+   * and our renderer. Must be done once, before commiting the output */
+  wlr_output_init_render(wlr_output, server->allocator, server->renderer);
+
+  /* The output may be disabled, switch it on. */
+  struct wlr_output_state state;
+  wlr_output_state_init(&state);
+  wlr_output_state_set_enabled(&state, true);
+
+  /* Some backends don't have modes. DRM+KMS does, and we need to set a mode
+   * before we can use the output. The mode is a tuple of (width, height,
+   * refresh rate), and each monitor supports only a specific set of modes. We
+   * just pick the monitor's preferred mode, a more sophisticated compositor
+   * would let the user configure it. */
+  struct wlr_output_mode *mode = wlr_output_preferred_mode(wlr_output);
+  if (mode != NULL) {
+    wlr_output_state_set_mode(&state, mode);
+  }
+
+  /* Atomically applies the new output state. */
+  wlr_output_commit_state(wlr_output, &state);
+  wlr_output_state_finish(&state);
+
+  /* Allocates and configures our state for this output */
+  struct montis_output *output = calloc(1, sizeof(*output));
+  output->wlr_output = wlr_output;
+  output->server = server;
+
+  /* Sets up a listener for the frame event. */
+  output->frame.notify = output_frame;
+  wl_signal_add(&wlr_output->events.frame, &output->frame);
+
+  /* Sets up a listener for the state request event. */
+  output->request_state.notify = output_request_state;
+  wl_signal_add(&wlr_output->events.request_state, &output->request_state);
+
+  /* Sets up a listener for the destroy event. */
+  output->destroy.notify = output_destroy;
+  wl_signal_add(&wlr_output->events.destroy, &output->destroy);
+
+  wl_list_insert(&server->outputs, &output->link);
+
+  /* Adds this to the output layout. The add_auto function arranges outputs
+   * from left-to-right in the order they appear. A more sophisticated
+   * compositor would let the user configure the arrangement of outputs in the
+   * layout.
+   *
+   * The output layout utility automatically adds a wl_output global to the
+   * display, which Wayland clients can see to find out information about the
+   * output (such as DPI, scale factor, manufacturer, etc).
+   */
+  struct wlr_output_layout_output *l_output =
+      wlr_output_layout_add_auto(server->output_layout, wlr_output);
+  struct wlr_scene_output *scene_output =
+      wlr_scene_output_create(server->scene, wlr_output);
+  wlr_scene_output_layout_add_output(server->scene_layout, l_output,
+                                     scene_output);
+}
+
+static void xdg_toplevel_map(struct wl_listener *listener, void *data)
+{
+  /* Called when the surface is mapped, or ready to display on-screen. */
+  struct montis_toplevel *toplevel = wl_container_of(listener, toplevel, map);
+
+  wl_list_insert(&toplevel->server->toplevels, &toplevel->link);
+
+  fprintf(stderr, "Surface map ...\n");
+  plugin_call_update_state(toplevel->server->plugin, plugin_handle_surface,
+                           toplevel, SURFACE_MAP);
+  fprintf(stderr, "/ Surface map ...\n");
+
+  focus_toplevel(toplevel, toplevel->xdg_toplevel->base->surface);
+}
+
+static void xdg_toplevel_unmap(struct wl_listener *listener, void *data)
+{
+  /* Called when the surface is unmapped, and should no longer be shown. */
+  struct montis_toplevel *toplevel = wl_container_of(listener, toplevel, unmap);
+
+  /* Reset the cursor mode if the grabbed toplevel was unmapped. */
+  if (toplevel == toplevel->server->grabbed_toplevel) {
+    reset_cursor_mode(toplevel->server);
+  }
+
+  fprintf(stderr, "Surface unmap ...\n");
+  plugin_call_update_state(toplevel->server->plugin, plugin_handle_surface,
+                           toplevel, SURFACE_UNMAP);
+  fprintf(stderr, "/ Surface map ...\n");
+
+  wl_list_remove(&toplevel->link);
+}
+
+static void xdg_toplevel_destroy(struct wl_listener *listener, void *data)
+{
+  /* Called when the xdg_toplevel is destroyed. */
+  struct montis_toplevel *toplevel =
+      wl_container_of(listener, toplevel, destroy);
+
+  wl_list_remove(&toplevel->map.link);
+  wl_list_remove(&toplevel->unmap.link);
+  wl_list_remove(&toplevel->destroy.link);
+  wl_list_remove(&toplevel->request_move.link);
+  wl_list_remove(&toplevel->request_resize.link);
+  wl_list_remove(&toplevel->request_maximize.link);
+  wl_list_remove(&toplevel->request_fullscreen.link);
+
+  fprintf(stderr, "Surface destroy ...\n");
+  plugin_call_update_state(toplevel->server->plugin, plugin_handle_surface,
+                           toplevel, SURFACE_DELETE);
+  fprintf(stderr, "/ Surface destroy ...\n");
+
+  free(toplevel);
+}
+
+static void begin_interactive(struct montis_toplevel *toplevel,
+                              enum montis_cursor_mode mode, uint32_t edges)
+{
+  /* This function sets up an interactive move or resize operation, where the
+   * compositor stops propegating pointer events to clients and instead
+   * consumes them itself, to move or resize windows. */
+  struct montis_server *server = toplevel->server;
+  struct wlr_surface *focused_surface =
+      server->seat->pointer_state.focused_surface;
+  if (toplevel->xdg_toplevel->base->surface !=
+      wlr_surface_get_root_surface(focused_surface)) {
+    /* Deny move/resize requests from unfocused clients. */
+    return;
+  }
+  server->grabbed_toplevel = toplevel;
+  server->cursor_mode = mode;
+
+  if (mode == TINYWL_CURSOR_MOVE) {
+    server->grab_x = server->cursor->x - toplevel->scene_tree->node.x;
+    server->grab_y = server->cursor->y - toplevel->scene_tree->node.y;
+  }
+  else {
+    struct wlr_box geo_box;
+    wlr_xdg_surface_get_geometry(toplevel->xdg_toplevel->base, &geo_box);
+
+    double border_x = (toplevel->scene_tree->node.x + geo_box.x) +
+                      ((edges & WLR_EDGE_RIGHT) ? geo_box.width : 0);
+    double border_y = (toplevel->scene_tree->node.y + geo_box.y) +
+                      ((edges & WLR_EDGE_BOTTOM) ? geo_box.height : 0);
+    server->grab_x = server->cursor->x - border_x;
+    server->grab_y = server->cursor->y - border_y;
+
+    server->grab_geobox = geo_box;
+    server->grab_geobox.x += toplevel->scene_tree->node.x;
+    server->grab_geobox.y += toplevel->scene_tree->node.y;
+
+    server->resize_edges = edges;
+  }
+}
+
+static void xdg_toplevel_request_move(struct wl_listener *listener, void *data)
+{
+  /* This event is raised when a client would like to begin an interactive
+   * move, typically because the user clicked on their client-side
+   * decorations. Note that a more sophisticated compositor should check the
+   * provided serial against a list of button press serials sent to this
+   * client, to prevent the client from requesting this whenever they want. */
+  struct montis_toplevel *toplevel =
+      wl_container_of(listener, toplevel, request_move);
+  begin_interactive(toplevel, TINYWL_CURSOR_MOVE, 0);
+}
+
+static void xdg_toplevel_request_resize(struct wl_listener *listener,
+                                        void *data)
+{
+  /* This event is raised when a client would like to begin an interactive
+   * resize, typically because the user clicked on their client-side
+   * decorations. Note that a more sophisticated compositor should check the
+   * provided serial against a list of button press serials sent to this
+   * client, to prevent the client from requesting this whenever they want. */
+  struct wlr_xdg_toplevel_resize_event *event = data;
+  struct montis_toplevel *toplevel =
+      wl_container_of(listener, toplevel, request_resize);
+  begin_interactive(toplevel, TINYWL_CURSOR_RESIZE, event->edges);
+}
+
+static void xdg_toplevel_request_maximize(struct wl_listener *listener,
+                                          void *data)
+{
+  /* This event is raised when a client would like to maximize itself,
+   * typically because the user clicked on the maximize button on
+   * client-side decorations. montis doesn't support maximization, but
+   * to conform to xdg-shell protocol we still must send a configure.
+   * wlr_xdg_surface_schedule_configure() is used to send an empty reply. */
+  struct montis_toplevel *toplevel =
+      wl_container_of(listener, toplevel, request_maximize);
+  wlr_xdg_surface_schedule_configure(toplevel->xdg_toplevel->base);
+}
+
+static void xdg_toplevel_request_fullscreen(struct wl_listener *listener,
+                                            void *data)
+{
+  /* Just as with request_maximize, we must send a configure here. */
+  struct montis_toplevel *toplevel =
+      wl_container_of(listener, toplevel, request_fullscreen);
+  wlr_xdg_surface_schedule_configure(toplevel->xdg_toplevel->base);
+}
+
+static void xdg_popup_commit(struct wl_listener *listener, void *data) {
+	/* Called when a new surface state is committed. */
+	struct montis_popup *popup = wl_container_of(listener, popup, commit);
+
+	if (popup->xdg_popup->base->initial_commit) {
+		/* When an xdg_surface performs an initial commit, the compositor must
+		 * reply with a configure so the client can map the surface.
+		 * montis sends an empty configure. A more sophisticated compositor
+		 * might change an xdg_popup's geometry to ensure it's not positioned
+		 * off-screen, for example. */
+		wlr_xdg_surface_schedule_configure(popup->xdg_popup->base);
+	}
+}
+
+static void xdg_popup_destroy(struct wl_listener *listener, void *data) {
+	/* Called when the xdg_popup is destroyed. */
+	struct montis_popup *popup = wl_container_of(listener, popup, destroy);
+
+	wl_list_remove(&popup->commit.link);
+	wl_list_remove(&popup->destroy.link);
+
+	free(popup);
+}
+
+static void server_new_xdg_popup(struct wl_listener *listener, void *data) {
+	/* This event is raised when a client creates a new popup. */
+	struct wlr_xdg_popup *xdg_popup = data;
+
+	struct montis_popup *popup = calloc(1, sizeof(*popup));
+	popup->xdg_popup = xdg_popup;
+
+	/* We must add xdg popups to the scene graph so they get rendered. The
+	 * wlroots scene graph provides a helper for this, but to use it we must
+	 * provide the proper parent scene node of the xdg popup. To enable this,
+	 * we always set the user data field of xdg_surfaces to the corresponding
+	 * scene node. */
+	struct wlr_xdg_surface *parent = wlr_xdg_surface_try_from_wlr_surface(xdg_popup->parent);
+	assert(parent != NULL);
+	struct wlr_scene_tree *parent_tree = parent->data;
+	xdg_popup->base->data = wlr_scene_xdg_surface_create(parent_tree, xdg_popup->base);
+
+	popup->commit.notify = xdg_popup_commit;
+	wl_signal_add(&xdg_popup->base->surface->events.commit, &popup->commit);
+
+	popup->destroy.notify = xdg_popup_destroy;
+	wl_signal_add(&xdg_popup->events.destroy, &popup->destroy);
+}
+
+static void xdg_toplevel_commit(struct wl_listener *listener, void *data) {
+	/* Called when a new surface state is committed. */
+	struct montis_toplevel *toplevel = wl_container_of(listener, toplevel, commit);
+
+	if (toplevel->xdg_toplevel->base->initial_commit) {
+		/* When an xdg_surface performs an initial commit, the compositor must
+		 * reply with a configure so the client can map the surface. montis
+		 * configures the xdg_toplevel with 0,0 size to let the client pick the
+		 * dimensions itself. */
+		wlr_xdg_toplevel_set_size(toplevel->xdg_toplevel, 0, 0);
+	}
+}
+
+static void server_new_xdg_toplevel(struct wl_listener *listener, void *data)
+{
+	/* This event is raised when a client creates a new toplevel (application window). */
+	struct montis_server *server = wl_container_of(listener, server, new_xdg_toplevel);
+	struct wlr_xdg_toplevel *xdg_toplevel = data;
+
+	/* Allocate a montis_toplevel for this surface */
+	struct montis_toplevel *toplevel = calloc(1, sizeof(*toplevel));
+	toplevel->server = server;
+	toplevel->xdg_toplevel = xdg_toplevel;
+	toplevel->scene_tree =
+		wlr_scene_xdg_surface_create(&toplevel->server->scene->tree, xdg_toplevel->base);
+	toplevel->scene_tree->node.data = toplevel;
+	xdg_toplevel->base->data = toplevel->scene_tree;
+
+	/* Listen to the various events it can emit */
+	toplevel->map.notify = xdg_toplevel_map;
+	wl_signal_add(&xdg_toplevel->base->surface->events.map, &toplevel->map);
+	toplevel->unmap.notify = xdg_toplevel_unmap;
+	wl_signal_add(&xdg_toplevel->base->surface->events.unmap, &toplevel->unmap);
+	toplevel->commit.notify = xdg_toplevel_commit;
+	wl_signal_add(&xdg_toplevel->base->surface->events.commit, &toplevel->commit);
+
+	toplevel->destroy.notify = xdg_toplevel_destroy;
+	wl_signal_add(&xdg_toplevel->events.destroy, &toplevel->destroy);
+
+	/* cotd */
+	toplevel->request_move.notify = xdg_toplevel_request_move;
+	wl_signal_add(&xdg_toplevel->events.request_move, &toplevel->request_move);
+	toplevel->request_resize.notify = xdg_toplevel_request_resize;
+	wl_signal_add(&xdg_toplevel->events.request_resize, &toplevel->request_resize);
+	toplevel->request_maximize.notify = xdg_toplevel_request_maximize;
+	wl_signal_add(&xdg_toplevel->events.request_maximize, &toplevel->request_maximize);
+	toplevel->request_fullscreen.notify = xdg_toplevel_request_fullscreen;
+	wl_signal_add(&xdg_toplevel->events.request_fullscreen, &toplevel->request_fullscreen);
+}
+
+int main(int argc, char *argv[])
+{
+  wlr_log_init(WLR_DEBUG, NULL);
+  char *startup_cmd = NULL;
+  char *plugin = NULL;
+
+  int c;
+  while ((c = getopt(argc, argv, "s:p:h")) != -1) {
+    switch (c) {
+    case 's':
+      startup_cmd = optarg;
+      break;
+    case 'p':
+      plugin = optarg;
+      break;
+    default:
+      printf("Usage: %s -p [plugin] [-s startup command]\n", argv[0]);
+      return 0;
+    }
+  }
+  if (optind < argc || !plugin) {
+    printf("Usage: %s -p [plugin] [-s startup command]\n", argv[0]);
+    return 0;
+  }
+
+  struct montis_server server = {0};
+
+  if (load_plugin_from_file(argc, argv, plugin, &server.plugin)) {
+    fprintf(stderr, "Failed to read plugin from file.\n");
+    return 1;
+  }
+
+  plugin_cold_start(&server.plugin);
+
+  /* The Wayland display is managed by libwayland. It handles accepting
+   * clients from the Unix socket, manging Wayland globals, and so on. */
+  server.wl_display = wl_display_create();
+  /* The backend is a wlroots feature which abstracts the underlying input and
+   * output hardware. The autocreate option will choose the most suitable
+   * backend based on the current environment, such as opening an X11 window
+   * if an X11 server is running. */
+  server.backend = wlr_backend_autocreate(
+      wl_display_get_event_loop(server.wl_display), &server.session);
+  if (server.backend == NULL) {
+    wlr_log(WLR_ERROR, "failed to create wlr_backend");
+    return 1;
+  }
+
+  /* Autocreates a renderer, either Pixman, GLES2 or Vulkan for us. The user
+   * can also specify a renderer using the WLR_RENDERER env var.
+   * The renderer is responsible for defining the various pixel formats it
+   * supports for shared memory, this configures that for clients. */
+  server.renderer = wlr_renderer_autocreate(server.backend);
+  if (server.renderer == NULL) {
+    wlr_log(WLR_ERROR, "failed to create wlr_renderer");
+    return 1;
+  }
+
+  wlr_renderer_init_wl_display(server.renderer, server.wl_display);
+
+  /* Autocreates an allocator for us.
+   * The allocator is the bridge between the renderer and the backend. It
+   * handles the buffer creation, allowing wlroots to render onto the
+   * screen */
+  server.allocator = wlr_allocator_autocreate(server.backend, server.renderer);
+  if (server.allocator == NULL) {
+    wlr_log(WLR_ERROR, "failed to create wlr_allocator");
+    return 1;
+  }
+
+  /* This creates some hands-off wlroots interfaces. The compositor is
+   * necessary for clients to allocate surfaces, the subcompositor allows to
+   * assign the role of subsurfaces to surfaces and the data device manager
+   * handles the clipboard. Each of these wlroots interfaces has room for you
+   * to dig your fingers in and play with their behavior if you want. Note that
+   * the clients cannot set the selection directly without compositor approval,
+   * see the handling of the request_set_selection event below.*/
+  wlr_compositor_create(server.wl_display, 5, server.renderer);
+  wlr_subcompositor_create(server.wl_display);
+  wlr_data_device_manager_create(server.wl_display);
+
+  /* Creates an output layout, which a wlroots utility for working with an
+   * arrangement of screens in a physical layout. */
+  server.output_layout = wlr_output_layout_create(server.wl_display);
+
+  /* Configure a listener to be notified when new outputs are available on the
+   * backend. */
+  wl_list_init(&server.outputs);
+  server.new_output.notify = server_new_output;
+  wl_signal_add(&server.backend->events.new_output, &server.new_output);
+
+  /* Create a scene graph. This is a wlroots abstraction that handles all
+   * rendering and damage tracking. All the compositor author needs to do
+   * is add things that should be rendered to the scene graph at the proper
+   * positions and then call wlr_scene_output_commit() to render a frame if
+   * necessary.
+   */
+  server.scene = wlr_scene_create();
+  server.scene_layout =
+      wlr_scene_attach_output_layout(server.scene, server.output_layout);
+
+  /* Set up xdg-shell version 3. The xdg-shell is a Wayland protocol which is
+   * used for application windows. For more detail on shells, refer to
+   * https://drewdevault.com/2018/07/29/Wayland-shells.html.
+   */
+  wl_list_init(&server.toplevels);
+  server.xdg_shell = wlr_xdg_shell_create(server.wl_display, 3);
+  server.new_xdg_toplevel.notify = server_new_xdg_toplevel;
+  wl_signal_add(&server.xdg_shell->events.new_toplevel,
+                &server.new_xdg_toplevel);
+  server.new_xdg_popup.notify = server_new_xdg_popup;
+  wl_signal_add(&server.xdg_shell->events.new_popup, &server.new_xdg_popup);
+
+  /*
+   * Creates a cursor, which is a wlroots utility for tracking the cursor
+   * image shown on screen.
+   */
+  server.cursor = wlr_cursor_create();
+  wlr_cursor_attach_output_layout(server.cursor, server.output_layout);
+
+  /* Creates an xcursor manager, another wlroots utility which loads up
+   * Xcursor themes to source cursor images from and makes sure that cursor
+   * images are available at all scale factors on the screen (necessary for
+   * HiDPI support). */
+  server.cursor_mgr = wlr_xcursor_manager_create(NULL, 24);
+
+  /*
+   * wlr_cursor *only* displays an image on screen. It does not move around
+   * when the pointer moves. However, we can attach input devices to it, and
+   * it will generate aggregate events for all of them. In these events, we
+   * can choose how we want to process them, forwarding them to clients and
+   * moving the cursor around. More detail on this process is described in
+   * https://drewdevault.com/2018/07/17/Input-handling-in-wlroots.html.
+   *
+   * And more comments are sprinkled throughout the notify functions above.
+   */
+  server.cursor_mode = TINYWL_CURSOR_PASSTHROUGH;
+  server.cursor_motion.notify = server_cursor_motion;
+  wl_signal_add(&server.cursor->events.motion, &server.cursor_motion);
+  server.cursor_motion_absolute.notify = server_cursor_motion_absolute;
+  wl_signal_add(&server.cursor->events.motion_absolute,
+                &server.cursor_motion_absolute);
+  server.cursor_button.notify = server_cursor_button;
+  wl_signal_add(&server.cursor->events.button, &server.cursor_button);
+  server.cursor_axis.notify = server_cursor_axis;
+  wl_signal_add(&server.cursor->events.axis, &server.cursor_axis);
+  server.cursor_frame.notify = server_cursor_frame;
+  wl_signal_add(&server.cursor->events.frame, &server.cursor_frame);
+
+  /*
+   * Configures a seat, which is a single "seat" at which a user sits and
+   * operates the computer. This conceptually includes up to one keyboard,
+   * pointer, touch, and drawing tablet device. We also rig up a listener to
+   * let us know when new input devices are available on the backend.
+   */
+  wl_list_init(&server.keyboards);
+  server.new_input.notify = server_new_input;
+  wl_signal_add(&server.backend->events.new_input, &server.new_input);
+  server.seat = wlr_seat_create(server.wl_display, "seat0");
+  server.request_cursor.notify = seat_request_cursor;
+  wl_signal_add(&server.seat->events.request_set_cursor,
+                &server.request_cursor);
+  server.request_set_selection.notify = seat_request_set_selection;
+  wl_signal_add(&server.seat->events.request_set_selection,
+                &server.request_set_selection);
+
+  /* Add a Unix socket to the Wayland display. */
+  const char *socket = wl_display_add_socket_auto(server.wl_display);
+  if (!socket) {
+    wlr_backend_destroy(server.backend);
+    return 1;
+  }
+
+  /* Start the backend. This will enumerate outputs and inputs, become the DRM
+   * master, etc */
+  if (!wlr_backend_start(server.backend)) {
+    wlr_backend_destroy(server.backend);
+    wl_display_destroy(server.wl_display);
+    return 1;
+  }
+
+  /* Set the WAYLAND_DISPLAY environment variable to our socket and run the
+   * startup command if requested. */
+  setenv("WAYLAND_DISPLAY", socket, true);
+  if (startup_cmd) {
+    if (fork() == 0) {
+      execl("/bin/sh", "/bin/sh", "-c", startup_cmd, (void *)NULL);
+    }
+  }
+  /* Run the Wayland event loop. This does not return until you exit the
+   * compositor. Starting the backend rigged up all of the necessary event
+   * loop configuration to listen to libinput events, DRM events, generate
+   * frame events at the refresh rate, and so on. */
+  wlr_log(WLR_INFO, "Running Wayland compositor on WAYLAND_DISPLAY=%s", socket);
+  wl_display_run(server.wl_display);
+
+  /* Once wl_display_run returns, we destroy all clients then shut down the
+   * server. */
+  wl_display_destroy_clients(server.wl_display);
+  wlr_scene_node_destroy(&server.scene->tree.node);
+  wlr_xcursor_manager_destroy(server.cursor_mgr);
+  wlr_output_layout_destroy(server.output_layout);
+  wl_display_destroy(server.wl_display);
+  return 0;
+}