1 files changed, 42 insertions, 0 deletions
diff --git a/src/libsystemd/sd-bus/bus-internal.c b/src/libsystemd/sd-bus/bus-internal.c
index fea796cd30..f4ab57f5bc 100644
--- a/src/libsystemd/sd-bus/bus-internal.c
+++ b/src/libsystemd/sd-bus/bus-internal.c
@@ -371,3 +371,45 @@ int bus_maybe_reply_error(sd_bus_message *m, int r, sd_bus_error *error) {
 
         return 1;
 }
+
+bool is_kdbus_wanted(void) {
+        _cleanup_free_ char *value = NULL;
+#ifdef ENABLE_KDBUS
+        const bool configured = true;
+#else
+        const bool configured = false;
+#endif
+        int r;
+
+        if (get_proc_cmdline_key("kdbus", NULL) > 0)
+                return true;
+
+        r = get_proc_cmdline_key("kdbus=", &value);
+        if (r <= 0)
+                return configured;
+
+        return parse_boolean(value) == 1;
+}
+
+bool is_kdbus_available(void) {
+        static int cached = -1;
+        _cleanup_close_ int fd = -1;
+        struct kdbus_cmd cmd = { .size = sizeof(cmd), .flags = KDBUS_FLAG_NEGOTIATE };
+
+        if (cached >= 0)
+                return (bool) cached;
+
+        if (!is_kdbus_wanted()) {
+                cached = false;
+                return false;
+        }
+
+        fd = open("/sys/fs/kdbus/control", O_RDWR | O_CLOEXEC | O_NONBLOCK | O_NOCTTY);
+        if (fd < 0) {
+                cached = false;
+                return false;
+        }
+
+        cached = ioctl(fd, KDBUS_CMD_BUS_MAKE, &cmd) >= 0;
+        return cached;
+}