backend/session: decouple udev

backend/session/session_libudev.c

@@ -0,0 +1,147 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <libudev.h>
+#include <string.h>
+#include <stdbool.h>
+#include <assert.h>
+#include <wlr/backend/session.h>
+#include "backend/session/session.h"
+
+struct drm_event_monitor {
+	struct udev *udev;
+	struct udev_monitor *mon;
+};
+
+struct drm_event_monitor *monitor_drm_events(int *fd) {
+	struct drm_event_monitor *ctx = calloc(1, sizeof(*ctx));
+	if (!ctx) {
+		return NULL;
+	}
+	ctx->udev = udev_new();
+	if (!ctx->udev) {
+		free(ctx);
+		return NULL;
+	}
+	ctx->mon = udev_monitor_new_from_netlink(ctx->udev, "udev");
+	if (!ctx->mon) {
+		udev_unref(ctx->udev);
+		free(ctx);
+		return NULL;
+	}
+	udev_monitor_filter_add_match_subsystem_devtype(ctx->mon, "drm", NULL);
+	udev_monitor_enable_receiving(ctx->mon);
+	*fd = udev_monitor_get_fd(ctx->mon);
+	return ctx;
+}
+
+void drm_event_monitor_free(struct drm_event_monitor *ctx) {
+	udev_monitor_unref(ctx->mon);
+	udev_unref(ctx->udev);
+	free(ctx);
+}
+
+static void populate_drm_event(struct drm_event_content *ev,
+		struct udev_device *dev) {
+	memset(ev, 0, sizeof(*ev));
+
+	const char *devnode = udev_device_get_devnode(dev);
+	if (devnode) {
+		int len = snprintf(ev->devnode, sizeof(ev->devnode), "%s", devnode);
+		assert((size_t)len < sizeof(ev->devnode));
+	}
+	ev->devnum = udev_device_get_devnum(dev);
+
+	const char *action = udev_device_get_action(dev);
+	if (strcmp(action, "add") == 0) {
+		ev->type = DRM_EVENT_ACTION_ADD;
+	} else if (strcmp(action, "change") == 0) {
+		ev->type = DRM_EVENT_ACTION_CHANGE;
+	} else if (strcmp(action, "remove") == 0) {
+		ev->type = DRM_EVENT_ACTION_REMOVE;
+	}
+
+	const char *hotplug = udev_device_get_property_value(dev, "HOTPLUG");
+	if (hotplug != NULL && strcmp(hotplug, "1") == 0) {
+		ev->has_lease = false;
+
+		const char *connector =
+			udev_device_get_property_value(dev, "CONNECTOR");
+		if (connector != NULL) {
+			ev->conn_id = strtoul(connector, NULL, 10);
+		}
+
+		const char *prop =
+			udev_device_get_property_value(dev, "PROPERTY");
+		if (prop != NULL) {
+			ev->prop_id = strtoul(prop, NULL, 10);
+		}
+
+		return;
+	}
+
+	const char *lease = udev_device_get_property_value(dev, "LEASE");
+	if (lease != NULL && strcmp(lease, "1") == 0) {
+		ev->has_lease = true;
+	}
+}
+
+int receive_drm_device(struct drm_event_monitor *ctx,
+		struct drm_event_content *ev) {
+	struct udev_device *dev = udev_monitor_receive_device(ctx->mon);
+	if (!dev) {
+		return -1;
+	}
+	populate_drm_event(ev, dev);
+	udev_device_unref(dev);
+	return 0;
+}
+
+static struct udev_device *get_udev_device_from_devnode(struct udev *udev,
+		const char *devnode) {
+	const char *sysname = strrchr(devnode, '/');
+	if (!sysname) {
+		return NULL;
+	}
+	sysname += 1;
+	struct udev_device *dev =
+		udev_device_new_from_subsystem_sysname(udev, "drm", sysname);
+	if (!dev) {
+		return NULL;
+	}
+	return dev;
+}
+
+// XXX: move it to libseat?
+const char *get_device_seat(struct drm_event_monitor *ctx, const char *devnode) {
+	struct udev_device *dev = get_udev_device_from_devnode(ctx->udev, devnode);
+	if (!dev) {
+		return NULL;
+	}
+	const char *seat = udev_device_get_property_value(dev, "ID_SEAT");
+	udev_device_unref(dev);
+	return seat;
+}
+
+// XXX: use sysfs directly?
+bool is_drm_device_primary(struct drm_event_monitor *ctx, const char *devnode) {
+	struct udev_device *dev = get_udev_device_from_devnode(ctx->udev, devnode);
+	if (!dev) {
+		return false;
+	}
+	const char *boot_display = udev_device_get_sysattr_value(dev, "boot_display");
+	if (boot_display && strcmp(boot_display, "1") == 0) {
+		udev_device_unref(dev);
+		return true;
+	}
+	// 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) {
+		udev_device_unref(dev);
+		return false;
+	}
+	const char *id = udev_device_get_sysattr_value(pci, "boot_vga");
+	bool primary = id && strcmp(id, "1") == 0;
+	udev_device_unref(dev);
+	return primary;
+}