Add support for LZNT1 decompression.

src/core/lib/LZNT1.mjs

@@ -0,0 +1,88 @@
+/**
+ *
+ * LZNT1 Decompress.
+ *
+ * @author 0xThiebaut [thiebaut.dev]
+ * @copyright Crown Copyright 2023
+ * @license Apache-2.0
+ *
+ * https://github.com/Velocidex/go-ntfs/blob/master/parser%2Flznt1.go
+ */
+
+import Utils from "../Utils.mjs";
+import OperationError from "../errors/OperationError.mjs";
+
+const COMPRESSED_MASK = 1 << 15,
+    SIZE_MASK = (1 << 12) - 1;
+
+/**
+ * @param {number} offset
+ * @returns {number}
+ */
+function getDisplacement(offset) {
+    let result = 0;
+    while (offset >= 0x10) {
+        offset >>= 1;
+        result += 1;
+    }
+    return result;
+}
+
+/**
+ * @param {byteArray} compressed
+ * @returns {byteArray}
+ */
+export function decompress(compressed) {
+    const decompressed = Array();
+    let coffset = 0;
+
+    while (coffset + 2 <= compressed.length) {
+        const doffset = decompressed.length;
+
+        const blockHeader = Utils.byteArrayToInt(compressed.slice(coffset, coffset + 2), "little");
+        coffset += 2;
+
+        const size = blockHeader & SIZE_MASK;
+        const blockEnd = coffset + size + 1;
+
+        if (size === 0) {
+            break;
+        } else if (compressed.length < coffset + size) {
+            throw new OperationError("Malformed LZNT1 stream: Block too small! Has the stream been truncated?");
+        }
+
+        if ((blockHeader & COMPRESSED_MASK) !== 0) {
+            while (coffset < blockEnd) {
+                let header = compressed[coffset++];
+
+                for (let i = 0; i < 8 && coffset < blockEnd; i++) {
+                    if ((header & 1) === 0) {
+                        decompressed.push(compressed[coffset++]);
+                    } else {
+                        const pointer = Utils.byteArrayToInt(compressed.slice(coffset, coffset + 2), "little");
+                        coffset += 2;
+
+                        const displacement = getDisplacement(decompressed.length - doffset - 1);
+                        const symbolOffset = (pointer >> (12 - displacement)) + 1;
+                        const symbolLength = (pointer & (0xFFF >> displacement)) + 2;
+                        const shiftOffset = decompressed.length - symbolOffset;
+
+                        for (let shiftDelta = 0; shiftDelta < symbolLength + 1; shiftDelta++) {
+                            const shift = shiftOffset + shiftDelta;
+                            if (shift < 0 || decompressed.length <= shift) {
+                                throw new OperationError("Malformed LZNT1 stream: Invalid shift!");
+                            }
+                            decompressed.push(decompressed[shift]);
+                        }
+                    }
+                    header >>= 1;
+                }
+            }
+        } else {
+            decompressed.push(...compressed.slice(coffset, coffset + size + 1));
+            coffset += size + 1;
+        }
+    }
+
+    return decompressed;
+}