Safe get of led devnode

Cargo.lock

@@ -374,6 +374,16 @@ dependencies = [
  "take_mut",
 ]
 
+[[package]]
+name = "libudev-sys"
+version = "0.1.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "3c8469b4a23b962c1396b9b451dda50ef5b283e8dd309d69033475fa9b334324"
+dependencies = [
+ "libc",
+ "pkg-config",
+]
+
 [[package]]
 name = "libusb1-sys"
 version = "0.3.7"
@@ -648,6 +658,7 @@ dependencies = [
  "serde_json",
  "sysfs-class",
  "tokio",
+ "udev",
 ]
 
 [[package]]
@@ -869,6 +880,16 @@ dependencies = [
  "syn",
 ]
 
+[[package]]
+name = "udev"
+version = "0.4.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "24953d50a3bce0f5f5a9a2766567072dc9af8096f8c40ea81815da651066bc9f"
+dependencies = [
+ "libc",
+ "libudev-sys",
+]
+
 [[package]]
 name = "unicode-xid"
 version = "0.2.1"