How is the nix hash for a directory generated?

jlesquembre · May 4, 2022, 2:54pm

I implemented the NAR serialization algorithm from https://edolstra.github.io/pubs/phd-thesis.pdf (Figure 5.2, page 101) in clojure:

github.com

jlesquembre/clj-nix/blob/928054c41f9f3078c5498efb55f81c2b635b2c5d/src/cljnix/nix.clj#L30-L139


      
          ;; NAR serialization algorithm
          ;; See https://edolstra.github.io/pubs/phd-thesis.pdf (Figure 5.2, page 101)
          
          
(defn int-n
            "NAR serialization algorithm
             int(n)"
            [n]
            (-> (ByteBuffer/allocate Long/BYTES)
                (.order ByteOrder/LITTLE_ENDIAN)
                (.putInt (int n))
                (.array)))
          
          
(defn pad
            "NAR serialization algorithm
             pad(s)"
            [n sink]
            (let [pad (mod (- 8 n)
                         8)]
              (when-not (zero? pad)
                (bs/transfer (byte-array pad) sink))))

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The hash from the NAR is the hash for a directory

Thanks to you both @NobbZ @abathur