/
bytes.clj
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/
bytes.clj
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;; Copyright (c) 2015-2020 Andrey Antukh <niwi@niwi.nz>
;;
;; Licensed under the Apache License, Version 2.0 (the "License")
;; you may not use this file except in compliance with the License.
;; You may obtain a copy of the License at
;;
;; http://www.apache.org/licenses/LICENSE-2.0
;;
;; Unless required by applicable law or agreed to in writing, software
;; distributed under the License is distributed on an "AS IS" BASIS,
;; WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
;; See the License for the specific language governing permissions and
;; limitations under the License.
(ns buddy.core.bytes
"A collection of functions for work with byte arrays
and bytes."
(:refer-clojure :exclude [concat bytes?])
(:import java.nio.ByteBuffer
java.util.Arrays))
(def ^:private +bytes-class+
(Class/forName "[B"))
(defn bytes?
"Test if a first parameter is a byte
array or not."
[x]
(if (nil? x)
false
(= +bytes-class+ (.getClass ^Object x))))
(defn fill!
"Assigns the specified byte value to each element
of the specified array of bytes."
([^bytes input val]
(Arrays/fill input (byte val)))
([^bytes input val & {:keys [limit offset start end]}]
(let [start (or offset start 0)
end (or limit start (count input))]
(Arrays/fill input ^int start ^int end (byte val)))))
(defn slice
"Returns a new copy of the byte array but
offset and crop by start and end indices."
[^bytes input ^long start ^long end]
(Arrays/copyOfRange input start end))
(defn copy
"Is a specialized version of slice that
just copy the byte array."
[^bytes input]
(let [length (count input)
buffer (byte-array length)]
(System/arraycopy input 0 buffer 0 length)
buffer))
(defn equals?
"Test whether two sequences of characters or bytes are equal in a way that
protects against timing attacks. Note that this does not prevent an attacker
from discovering the *length* of the data being compared."
[a b]
(let [a (map int a), b (map int b)]
(if (and a b (= (count a) (count b)))
(zero? (reduce bit-or 0 (map bit-xor a b)))
false)))
(defn concat
"Given N number of byte arrays, concat them in
one unique byte array and return it."
[& parts]
(byte-array (for [ar parts
i ar] i)))