wlroots/backend/session/session.c

#include <assert.h>
#include <stdarg.h>
#include <stddef.h>
#include <stdlib.h>
#include <stdio.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <unistd.h>
#include <wayland-server-core.h>
#include <wlr/backend/session.h>
#include <wlr/config.h>
#include <wlr/util/log.h>
#include <xf86drm.h>
#include <xf86drmMode.h>
#include <glob.h>
#include "backend/session/session.h"
#include "util/time.h"

#include <libseat.h>

#define WAIT_GPU_TIMEOUT 10000 // ms

static void handle_enable_seat(struct libseat *seat, void *data) {
	struct wlr_session *session = data;
	session->active = true;
	wl_signal_emit_mutable(&session->events.active, NULL);
}

static void handle_disable_seat(struct libseat *seat, void *data) {
	struct wlr_session *session = data;
	session->active = false;
	wl_signal_emit_mutable(&session->events.active, NULL);
	libseat_disable_seat(session->seat_handle);
}

static int libseat_event(int fd, uint32_t mask, void *data) {
	struct wlr_session *session = data;
	if (mask & (WL_EVENT_HANGUP | WL_EVENT_ERROR)) {
		if (mask & WL_EVENT_ERROR) {
			wlr_log(WLR_ERROR, "Failed to wait for libseat event");
		} else {
			wlr_log(WLR_INFO, "Failed to wait for libseat event");
		}
		wlr_session_destroy(session);
		return 0;
	}
	if (libseat_dispatch(session->seat_handle, 0) == -1) {
		wlr_log_errno(WLR_ERROR, "Failed to dispatch libseat");
		wlr_session_destroy(session);
	}
	return 1;
}

static struct libseat_seat_listener seat_listener = {
	.enable_seat = handle_enable_seat,
	.disable_seat = handle_disable_seat,
};

static enum wlr_log_importance libseat_log_level_to_wlr(
		enum libseat_log_level level) {
	switch (level) {
	case LIBSEAT_LOG_LEVEL_ERROR:
		return WLR_ERROR;
	case LIBSEAT_LOG_LEVEL_INFO:
		return WLR_INFO;
	default:
		return WLR_DEBUG;
	}
}

static void log_libseat(enum libseat_log_level level,
		const char *fmt, va_list args) {
	enum wlr_log_importance importance = libseat_log_level_to_wlr(level);

	static char wlr_fmt[1024];
	snprintf(wlr_fmt, sizeof(wlr_fmt), "[libseat] %s", fmt);

	_wlr_vlog(importance, wlr_fmt, args);
}

static int libseat_session_init(struct wlr_session *session,
		struct wl_event_loop *event_loop) {
	libseat_set_log_handler(log_libseat);
	libseat_set_log_level(LIBSEAT_LOG_LEVEL_INFO);

	// libseat will take care of updating the logind state if necessary
	setenv("XDG_SESSION_TYPE", "wayland", 1);

	session->seat_handle = libseat_open_seat(&seat_listener, session);
	if (session->seat_handle == NULL) {
		wlr_log_errno(WLR_ERROR, "Unable to create seat");
		return -1;
	}

	const char *seat_name = libseat_seat_name(session->seat_handle);
	if (seat_name == NULL) {
		wlr_log_errno(WLR_ERROR, "Unable to get seat info");
		goto error;
	}
	snprintf(session->seat, sizeof(session->seat), "%s", seat_name);

	session->libseat_event = wl_event_loop_add_fd(event_loop, libseat_get_fd(session->seat_handle),
		WL_EVENT_READABLE, libseat_event, session);
	if (session->libseat_event == NULL) {
		wlr_log(WLR_ERROR, "Failed to create libseat event source");
		goto error;
	}

	// We may have received enable_seat immediately after the open_seat result,
	// so, dispatch once without timeout to speed up activation.
	if (libseat_dispatch(session->seat_handle, 0) == -1) {
		wlr_log_errno(WLR_ERROR, "libseat dispatch failed");
		goto error_dispatch;
	}

	wlr_log(WLR_INFO, "Successfully loaded libseat session");
	return 0;

error_dispatch:
	wl_event_source_remove(session->libseat_event);
	session->libseat_event = NULL;
error:
	libseat_close_seat(session->seat_handle);
	session->seat_handle = NULL;
	return -1;
}

static void libseat_session_finish(struct wlr_session *session) {
	libseat_close_seat(session->seat_handle);
	wl_event_source_remove(session->libseat_event);
	session->seat_handle = NULL;
	session->libseat_event = NULL;
}

static bool is_drm_card(const char *sysname) {
	const char prefix[] = DRM_PRIMARY_MINOR_NAME;
	if (strncmp(sysname, prefix, strlen(prefix)) != 0) {
		return false;
	}
	for (size_t i = strlen(prefix); sysname[i] != '\0'; i++) {
		if (sysname[i] < '0' || sysname[i] > '9') {
			return false;
		}
	}
	return true;
}

static int handle_device_event(int fd, uint32_t mask, void *data) {
	struct wlr_session *session = data;

	struct drm_event_content ev;
	if (receive_drm_device(session->drm_handle, &ev) < 0) {
		return 1;
	}
	wlr_log(WLR_DEBUG, "drm event for %s", ev.devnode);

	if (!is_drm_card(ev.devnode)) {
		return 1;
	}

	const char *seat = get_device_seat(session->drm_handle, ev.devnode);
	if (!seat) {
		seat = "seat0";
	}
	if (session->seat[0] != '\0' && strcmp(session->seat, seat) != 0) {
		return 1;
	}

	struct wlr_device *dev;
	switch (ev.type) {
	case DRM_EVENT_ACTION_ADD:
		wl_list_for_each(dev, &session->devices, link) {
			if (dev->dev == ev.devnum) {
				wlr_log(WLR_DEBUG, "Skipping duplicate device %s", ev.devnode);
				return 1;
			}
		}

		wlr_log(WLR_DEBUG, "DRM device %s added", ev.devnode);
		struct wlr_session_add_event event = {
			.path = ev.devnode,
		};
		wl_signal_emit_mutable(&session->events.add_drm_card, &event);
		break;
	case DRM_EVENT_ACTION_CHANGE:
		wl_list_for_each(dev, &session->devices, link) {
			if (dev->dev == ev.devnum) {
				wlr_log(WLR_DEBUG, "DRM device %s changed", ev.devnode);
				struct wlr_device_change_event event = {0};
				event.hotplug.connector_id = ev.conn_id;
				event.hotplug.prop_id = ev.prop_id;
				event.type = ev.has_lease ?
					WLR_DEVICE_LEASE : WLR_DEVICE_HOTPLUG;
				wl_signal_emit_mutable(&dev->events.change, &event);
				break;
			}
		}
		break;
	case DRM_EVENT_ACTION_REMOVE:
		wl_list_for_each(dev, &session->devices, link) {
			if (dev->dev == ev.devnum) {
				wlr_log(WLR_DEBUG, "DRM device %s removed", ev.devnode);
				wl_signal_emit_mutable(&dev->events.remove, NULL);
				break;
			}
		}
		break;
	case DRM_EVENT_ACTION_NONE:
		wlr_log(WLR_DEBUG, "Unknown device event");
		break;
	}
	return 1;
}

static void handle_event_loop_destroy(struct wl_listener *listener, void *data) {
	struct wlr_session *session =
		wl_container_of(listener, session, event_loop_destroy);
	wlr_session_destroy(session);
}

struct wlr_session *wlr_session_create(struct wl_event_loop *event_loop) {
	struct wlr_session *session = calloc(1, sizeof(*session));
	if (!session) {
		wlr_log_errno(WLR_ERROR, "Allocation failed");
		return NULL;
	}

	session->event_loop = event_loop;
	wl_signal_init(&session->events.active);
	wl_signal_init(&session->events.add_drm_card);
	wl_signal_init(&session->events.destroy);
	wl_list_init(&session->devices);

	if (libseat_session_init(session, event_loop) == -1) {
		wlr_log(WLR_ERROR, "Failed to load session backend");
		goto error_open;
	}

	int fd = -1;
	session->drm_handle = monitor_drm_events(&fd);
	if (!session->drm_handle) {
		wlr_log(WLR_ERROR, "Failed to create device monitor context");
		goto error_session;
	}

	session->drm_event = wl_event_loop_add_fd(event_loop, fd,
		WL_EVENT_READABLE, handle_device_event, session);
	if (!session->drm_event) {
		wlr_log_errno(WLR_ERROR, "Failed to create device event source");
		goto error_mon;
	}

	session->event_loop_destroy.notify = handle_event_loop_destroy;
	wl_event_loop_add_destroy_listener(event_loop, &session->event_loop_destroy);

	return session;

error_mon:
	drm_event_monitor_free(session->drm_handle);
error_session:
	libseat_session_finish(session);
error_open:
	free(session);
	return NULL;
}

void wlr_session_destroy(struct wlr_session *session) {
	if (!session) {
		return;
	}

	wl_signal_emit_mutable(&session->events.destroy, session);

	assert(wl_list_empty(&session->events.active.listener_list));
	assert(wl_list_empty(&session->events.add_drm_card.listener_list));
	assert(wl_list_empty(&session->events.destroy.listener_list));

	wl_list_remove(&session->event_loop_destroy.link);

	wl_event_source_remove(session->drm_event);
	drm_event_monitor_free(session->drm_handle);

	struct wlr_device *dev, *tmp_dev;
	wl_list_for_each_safe(dev, tmp_dev, &session->devices, link) {
		wlr_session_close_file(session, dev);
	}

	libseat_session_finish(session);
	free(session);
}

struct wlr_device *wlr_session_open_file(struct wlr_session *session,
		const char *path) {
	int fd;
	int device_id = libseat_open_device(session->seat_handle, path, &fd);
	if (device_id == -1) {
		wlr_log_errno(WLR_ERROR, "Failed to open device: '%s'", path);
		return NULL;
	}

	struct wlr_device *dev = malloc(sizeof(*dev));
	if (!dev) {
		wlr_log_errno(WLR_ERROR, "Allocation failed");
		goto error;
	}

	struct stat st;
	if (fstat(fd, &st) < 0) {
		wlr_log_errno(WLR_ERROR, "Stat failed");
		goto error;
	}

	dev->fd = fd;
	dev->dev = st.st_rdev;
	dev->device_id = device_id;
	wl_signal_init(&dev->events.change);
	wl_signal_init(&dev->events.remove);
	wl_list_insert(&session->devices, &dev->link);

	return dev;

error:
	libseat_close_device(session->seat_handle, device_id);
	free(dev);
	close(fd);
	return NULL;
}

void wlr_session_close_file(struct wlr_session *session,
		struct wlr_device *dev) {
	if (libseat_close_device(session->seat_handle, dev->device_id) == -1) {
		wlr_log_errno(WLR_ERROR, "Failed to close device %d", dev->device_id);
	}

	assert(wl_list_empty(&dev->events.change.listener_list));
	// TODO: assert that the "remove" listener list is empty as well. Listeners
	// will typically call wlr_session_close_file() in response, and
	// wl_signal_emit_mutable() installs two phantom listeners, so we'd count
	// these two.

	close(dev->fd);
	wl_list_remove(&dev->link);
	free(dev);
}

bool wlr_session_change_vt(struct wlr_session *session, unsigned vt) {
	if (!session) {
		return false;
	}
	return libseat_switch_session(session->seat_handle, vt) == 0;
}

/* Tests if 'path' is KMS compatible by trying to open it. Returns the opened
 * device on success. */
struct wlr_device *session_open_if_kms(struct wlr_session *session,
		const char *path) {
	if (!path) {
		return NULL;
	}

	struct wlr_device *dev = wlr_session_open_file(session, path);
	if (!dev) {
		return NULL;
	}

	if (!drmIsKMS(dev->fd)) {
		wlr_log(WLR_DEBUG, "Ignoring '%s': not a KMS device", path);
		wlr_session_close_file(session, dev);
		return NULL;
	}

	return dev;
}

static ssize_t explicit_find_gpus(struct wlr_session *session,
		size_t ret_len, struct wlr_device *ret[static ret_len], const char *str) {
	char *gpus = strdup(str);
	if (!gpus) {
		wlr_log_errno(WLR_ERROR, "Allocation failed");
		return -1;
	}

	size_t i = 0;
	char *save;
	char *ptr = strtok_r(gpus, ":", &save);
	do {
		if (i >= ret_len) {
			break;
		}

		ret[i] = session_open_if_kms(session, ptr);
		if (!ret[i]) {
			wlr_log(WLR_ERROR, "Unable to open %s as KMS device", ptr);
		} else {
			++i;
		}
	} while ((ptr = strtok_r(NULL, ":", &save)));

	free(gpus);
	return i;
}

struct find_gpus_add_handler {
	bool added;
	struct wl_listener listener;
};

static void find_gpus_handle_add(struct wl_listener *listener, void *data) {
	struct find_gpus_add_handler *handler =
		wl_container_of(listener, handler, listener);
	handler->added = true;
}

ssize_t wlr_session_find_gpus(struct wlr_session *session,
		size_t ret_len, struct wlr_device **ret) {
	const char *explicit = getenv("WLR_DRM_DEVICES");
	if (explicit) {
		wlr_log(WLR_INFO, "Opening fixed list of KMS devices from WLR_DRM_DEVICES: %s", explicit);
		return explicit_find_gpus(session, ret_len, ret, explicit);
	}

	static const char *node_glob = DRM_DIR_NAME "/" DRM_PRIMARY_MINOR_NAME "[0-9]*";
	glob_t gl;
	if (glob(node_glob, 0, NULL, &gl) != 0) {
		return -1;
	}
	if (gl.gl_pathc == 0) {
		globfree(&gl);
		wlr_log(WLR_INFO, "Waiting for a KMS device");

		struct find_gpus_add_handler handler = {0};
		handler.listener.notify = find_gpus_handle_add;
		wl_signal_add(&session->events.add_drm_card, &handler.listener);

		int64_t started_at = get_current_time_msec();
		int64_t timeout = WAIT_GPU_TIMEOUT;
		while (!handler.added) {
			int ret = wl_event_loop_dispatch(session->event_loop, (int)timeout);
			if (ret < 0) {
				wlr_log_errno(WLR_ERROR, "Failed to wait for KMS device: "
					"wl_event_loop_dispatch failed");
				return -1;
			}

			int64_t now = get_current_time_msec();
			if (now >= started_at + WAIT_GPU_TIMEOUT) {
				break;
			}
			timeout = started_at + WAIT_GPU_TIMEOUT - now;
		}

		wl_list_remove(&handler.listener.link);
		if (glob(node_glob, 0, NULL, &gl) != 0) {
			return -1;
		}
	}

	size_t ret_num = 0;
	for (size_t i = 0; i < gl.gl_pathc && ret_num < ret_len; i++) {
		const char *devnode = gl.gl_pathv[i];
		const char *seat = get_device_seat(session->drm_handle, devnode);
		if (!seat) {
			seat = "seat0";
		}
		if (session->seat[0] && strcmp(session->seat, seat) != 0) {
			continue;
		}

		bool is_primary = is_drm_device_primary(session->drm_handle, devnode);
		struct wlr_device *wlr_dev =
			session_open_if_kms(session, devnode);
		if (!wlr_dev) {
			continue;
		}

		ret[ret_num] = wlr_dev;
		if (is_primary) {
			struct wlr_device *tmp = ret[0];
			ret[0] = ret[ret_num];
			ret[ret_num] = tmp;
		}

		++ret_num;
	}

	globfree(&gl);
	return ret_num;
}