underflow.clj

(require '[clojure.string :as str])
(import '(java.nio ByteBuffer))

(def testdata "00 05 61 61 61 61 61 00 05 61 61 61 61 61")

(defn parse [^ByteBuffer stream] nil)

(defn load-nbt-string
  [^ByteBuffer stream]
  (let [l (.getShort stream) data (byte-array l)]
    (.get stream data)
    (String. data)))

(defn load-nbt-byte-array
  [^ByteBuffer stream]
  (let [l (.getInt stream) data (byte-array l)]
    (.get stream data)
    data))

(let [
  hexBytes (str/split testdata #" ")
  bytes (map #(Integer/parseInt % 16) hexBytes)
  ba (byte-array (count bytes) bytes)
  buf (. ByteBuffer (wrap ba))]
  ; if these are both load-nbt-string, it works
  (prn (load-nbt-byte-array buf) (load-nbt-string buf)))

; instead:
; Syntax error (BufferUnderflowException) compiling at (foo.clj:20:1).
; null