Merge wlr_udev into wlr_session

backend/session/direct.c

@@ -223,8 +223,6 @@ static struct wlr_session *direct_session_create(struct wl_display *disp) {
 	snprintf(session->base.seat, sizeof(session->base.seat), "%s", seat);
 	session->base.drm_fd = -1;
 	session->base.impl = &session_direct;
-	session->base.active = true;
-	wl_signal_init(&session->base.session_signal);
 	return &session->base;
 
 error_ipc:

backend/session/logind.c

@@ -376,8 +376,6 @@ static struct wlr_session *logind_session_create(struct wl_display *disp) {
 
 	session->base.drm_fd = -1;
 	session->base.impl = &session_logind;
-	session->base.active = true;
-	wl_signal_init(&session->base.session_signal);
 	return &session->base;
 
 error_bus:

backend/session/session.c

@@ -1,9 +1,25 @@
+#include <assert.h>
 #include <stddef.h>
 #include <stdarg.h>
+#include <stdlib.h>
+#include <sys/stat.h>
+#include <sys/types.h>
+#include <libudev.h>
+#include <wayland-server.h>
+#include <xf86drm.h>
+#include <xf86drmMode.h>
 #include <wlr/backend/session.h>
 #include <wlr/backend/session/interface.h>
 #include <wlr/util/log.h>
 
+struct device {
+	int fd;
+	dev_t dev;
+	struct wl_signal signal;
+
+	struct wl_list link;
+};
+
 extern const struct session_impl session_logind;
 extern const struct session_impl session_direct;
 
@@ -15,17 +31,88 @@ static const struct session_impl *impls[] = {
 	NULL,
 };
 
-struct wlr_session *wlr_session_create(struct wl_display *disp) {
-	const struct session_impl **iter;
+static int udev_event(int fd, uint32_t mask, void *data) {
+	struct wlr_session *session = data;
 
-	for (iter = impls; *iter; ++iter) {
-		struct wlr_session *session = (*iter)->create(disp);
-		if (session) {
-			return session;
+	struct udev_device *udev_dev = udev_monitor_receive_device(session->mon);
+	if (!udev_dev) {
+		return 1;
+	}
+
+	const char *action = udev_device_get_action(udev_dev);
+
+	wlr_log(L_DEBUG, "udev event for %s (%s)",
+		udev_device_get_sysname(udev_dev), action);
+
+	if (!action || strcmp(action, "change") != 0) {
+		goto out;
+	}
+
+	dev_t devnum = udev_device_get_devnum(udev_dev);
+	struct device *dev;
+
+	wl_list_for_each(dev, &session->devices, link) {
+		if (dev->dev == devnum) {
+			wl_signal_emit(&dev->signal, session);
+			break;
 		}
 	}
 
-	wlr_log(L_ERROR, "Failed to load session backend");
+out:
+	udev_device_unref(udev_dev);
+	return 1;
+}
+
+struct wlr_session *wlr_session_create(struct wl_display *disp) {
+	struct wlr_session *session = NULL;
+	const struct session_impl **iter;
+
+	for (iter = impls; !session && *iter; ++iter) {
+		session = (*iter)->create(disp);
+	}
+
+	if (!session) {
+		wlr_log(L_ERROR, "Failed to load session backend");
+		return NULL;
+	}
+
+	session->active = true;
+	wl_signal_init(&session->session_signal);
+	wl_list_init(&session->devices);
+
+	session->udev = udev_new();
+	if (!session->udev) {
+		wlr_log_errno(L_ERROR, "Failed to create udev context");
+		goto error_session;
+	}
+
+	session->mon = udev_monitor_new_from_netlink(session->udev, "udev");
+	if (!session->mon) {
+		wlr_log_errno(L_ERROR, "Failed to create udev monitor");
+		goto error_udev;
+	}
+
+	udev_monitor_filter_add_match_subsystem_devtype(session->mon, "drm", NULL);
+	udev_monitor_enable_receiving(session->mon);
+
+	struct wl_event_loop *event_loop = wl_display_get_event_loop(disp);
+	int fd = udev_monitor_get_fd(session->mon);
+
+	session->udev_event = wl_event_loop_add_fd(event_loop, fd,
+		WL_EVENT_READABLE, udev_event, session);
+	if (!session->udev_event) {
+		wlr_log_errno(L_ERROR, "Failed to create udev event source");
+		goto error_mon;
+	}
+
+	return session;
+
+error_mon:
+	udev_monitor_unref(session->mon);
+error_udev:
+	udev_unref(session->udev);
+error_session:
+	wlr_session_destroy(session);
 	return NULL;
 }
 
@@ -34,15 +121,69 @@ void wlr_session_destroy(struct wlr_session *session) {
 		return;
 	}
 
+	wl_event_source_remove(session->udev_event);
+	udev_monitor_unref(session->mon);
+	udev_unref(session->udev);
+
 	session->impl->destroy(session);
-};
+}
 
 int wlr_session_open_file(struct wlr_session *session, const char *path) {
-	return session->impl->open(session, path);
+	int fd = session->impl->open(session, path);
+	if (fd < 0) {
+		return fd;
+	}
+
+	struct device *dev = malloc(sizeof(*dev));
+	if (!dev) {
+		wlr_log_errno(L_ERROR, "Allocation failed");
+		goto error;
+	}
+
+	struct stat st;
+	if (fstat(fd, &st) < 0) {
+		wlr_log_errno(L_ERROR, "Stat failed");
+		goto error;
+	}
+
+	dev->fd = fd;
+	dev->dev = st.st_rdev;
+	wl_signal_init(&dev->signal);
+	wl_list_insert(&session->devices, &dev->link);
+
+	return fd;
+
+error:
+	free(dev);
+	return fd;
+}
+
+static struct device *find_device(struct wlr_session *session, int fd) {
+	struct device *dev;
+
+	wl_list_for_each(dev, &session->devices, link) {
+		if (dev->fd == fd) {
+			return dev;
+		}
+	}
+
+	wlr_log(L_ERROR, "Tried to use fd %d not opened by session", fd);
+	assert(0);
 }
 
 void wlr_session_close_file(struct wlr_session *session, int fd) {
+	struct device *dev = find_device(session, fd);
+
 	session->impl->close(session, fd);
+	wl_list_remove(&dev->link);
+	free(dev);
+}
+
+void wlr_session_signal_add(struct wlr_session *session, int fd,
+		struct wl_listener *listener) {
+	struct device *dev = find_device(session, fd);
+
+	wl_signal_add(&dev->signal, listener);
 }
 
 bool wlr_session_change_vt(struct wlr_session *session, unsigned vt) {
@@ -52,3 +193,119 @@ bool wlr_session_change_vt(struct wlr_session *session, unsigned vt) {
 
 	return session->impl->change_vt(session, vt);
 }
+
+/* Tests if 'path' is KMS compatible by trying to open it.
+ * It leaves the open device in *fd_out it it succeeds.
+ */
+static bool device_is_kms(struct wlr_session *restrict session,
+	const char *restrict path, int *restrict fd_out) {
+
+	int fd;
+
+	if (!path) {
+		return false;
+	}
+
+	fd = wlr_session_open_file(session, path);
+	if (fd < 0) {
+		return false;
+	}
+
+	drmModeRes *res = drmModeGetResources(fd);
+	if (!res) {
+		goto out_fd;
+	}
+
+	if (res->count_crtcs <= 0 || res->count_connectors <= 0 ||
+		res->count_encoders <= 0) {
+
+		goto out_res;
+	}
+
+	if (*fd_out >= 0) {
+		wlr_session_close_file(session, *fd_out);
+	}
+
+	*fd_out = fd;
+
+	drmModeFreeResources(res);
+	return true;
+
+out_res:
+	drmModeFreeResources(res);
+out_fd:
+	wlr_session_close_file(session, fd);
+	return false;
+}
+
+/* Tries to find the primary GPU by checking for the "boot_vga" attribute.
+ * If it's not found, it returns the first valid GPU it finds.
+ */
+int wlr_session_find_gpu(struct wlr_session *session) {
+	struct udev_enumerate *en = udev_enumerate_new(session->udev);
+	if (!en) {
+		wlr_log(L_ERROR, "Failed to create udev enumeration");
+		return -1;
+	}
+
+	udev_enumerate_add_match_subsystem(en, "drm");
+	udev_enumerate_add_match_sysname(en, "card[0-9]*");
+	udev_enumerate_scan_devices(en);
+
+	struct udev_list_entry *entry;
+	int fd = -1;
+
+	udev_list_entry_foreach(entry, udev_enumerate_get_list_entry(en)) {
+		bool is_boot_vga = false;
+
+		const char *path = udev_list_entry_get_name(entry);
+		struct udev_device *dev = udev_device_new_from_syspath(session->udev, path);
+		if (!dev) {
+			continue;
+		}
+
+		/*
+		const char *seat = udev_device_get_property_value(dev, "ID_SEAT");
+		if (!seat)
+			seat = "seat0";
+		if (strcmp(session->seat, seat) != 0) {
+			udev_device_unref(dev);
+			continue;
+		}
+		*/
+
+		// This is owned by 'dev', so we don't need to free it
+		struct udev_device *pci =
+			udev_device_get_parent_with_subsystem_devtype(dev, "pci", NULL);
+
+		if (pci) {
+			const char *id = udev_device_get_sysattr_value(pci, "boot_vga");
+			if (id && strcmp(id, "1") == 0) {
+				is_boot_vga = true;
+			}
+		}
+
+		// We already have a valid GPU
+		if (!is_boot_vga && fd >= 0) {
+			udev_device_unref(dev);
+			continue;
+		}
+
+		path = udev_device_get_devnode(dev);
+		if (!device_is_kms(session, path, &fd)) {
+			udev_device_unref(dev);
+			continue;
+		}
+
+		udev_device_unref(dev);
+
+		// We've found the primary GPU
+		if (is_boot_vga) {
+			break;
+		}
+	}
+
+	udev_enumerate_unref(en);
+
+	return fd;
+}