1 files changed, 156 insertions, 0 deletions
diff --git a/toolkit/components/lz4/lz4.js b/toolkit/components/lz4/lz4.js
new file mode 100644
index 000000000..8d4ffcf8e
--- /dev/null
+++ b/toolkit/components/lz4/lz4.js
@@ -0,0 +1,156 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this file,
+ * You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+"use strict";
+
+var SharedAll;
+var Primitives;
+if (typeof Components != "undefined") {
+  let Cu = Components.utils;
+  SharedAll = {};
+  Cu.import("resource://gre/modules/osfile/osfile_shared_allthreads.jsm", SharedAll);
+  Cu.import("resource://gre/modules/lz4_internal.js");
+  Cu.import("resource://gre/modules/ctypes.jsm");
+
+  this.EXPORTED_SYMBOLS = [
+    "Lz4"
+  ];
+  this.exports = {};
+} else if (typeof module != "undefined" && typeof require != "undefined") {
+  SharedAll = require("resource://gre/modules/osfile/osfile_shared_allthreads.jsm");
+  Primitives = require("resource://gre/modules/lz4_internal.js");
+} else {
+  throw new Error("Please load this module with Component.utils.import or with require()");
+}
+
+const MAGIC_NUMBER = new Uint8Array([109, 111, 122, 76, 122, 52, 48, 0]); // "mozLz4a\0"
+
+const BYTES_IN_SIZE_HEADER = ctypes.uint32_t.size;
+
+const HEADER_SIZE = MAGIC_NUMBER.byteLength + BYTES_IN_SIZE_HEADER;
+
+const EXPECTED_HEADER_TYPE = new ctypes.ArrayType(ctypes.uint8_t, HEADER_SIZE);
+const EXPECTED_SIZE_BUFFER_TYPE = new ctypes.ArrayType(ctypes.uint8_t, BYTES_IN_SIZE_HEADER);
+
+/**
+ * An error during (de)compression
+ *
+ * @param {string} operation The name of the operation ("compress", "decompress")
+ * @param {string} reason A reason to be used when matching errors. Must start
+ * with "because", e.g. "becauseInvalidContent".
+ * @param {string} message A human-readable message.
+ */
+function LZError(operation, reason, message) {
+  SharedAll.OSError.call(this);
+  this.operation = operation;
+  this[reason] = true;
+  this.message = message;
+}
+LZError.prototype = Object.create(SharedAll.OSError);
+LZError.prototype.toString = function toString() {
+  return this.message;
+};
+exports.Error = LZError;
+
+/**
+ * Compress a block to a form suitable for writing to disk.
+ *
+ * Compatibility note: For the moment, we are basing our code on lz4
+ * 1.3, which does not specify a *file* format. Therefore, we define
+ * our own format. Once lz4 defines a complete file format, we will
+ * migrate both |compressFileContent| and |decompressFileContent| to this file
+ * format. For backwards-compatibility, |decompressFileContent| will however
+ * keep the ability to decompress files provided with older versions of
+ * |compressFileContent|.
+ *
+ * Compressed files have the following layout:
+ *
+ * | MAGIC_NUMBER (8 bytes) | content size (uint32_t, little endian) | content, as obtained from lz4_compress |
+ *
+ * @param {TypedArray|void*} buffer The buffer to write to the disk.
+ * @param {object=} options An object that may contain the following fields:
+ *  - {number} bytes The number of bytes to read from |buffer|. If |buffer|
+ *    is an |ArrayBuffer|, |bytes| defaults to |buffer.byteLength|. If
+ *    |buffer| is a |void*|, |bytes| MUST be provided.
+ * @return {Uint8Array} An array of bytes suitable for being written to the
+ * disk.
+ */
+function compressFileContent(array, options = {}) {
+  // Prepare the output array
+  let inputBytes;
+  if (SharedAll.isTypedArray(array) && !(options && "bytes" in options)) {
+    inputBytes = array.byteLength;
+  } else if (options && options.bytes) {
+    inputBytes = options.bytes;
+  } else {
+    throw new TypeError("compressFileContent requires a size");
+  }
+  let maxCompressedSize = Primitives.maxCompressedSize(inputBytes);
+  let outputArray = new Uint8Array(HEADER_SIZE + maxCompressedSize);
+
+  // Compress to output array
+  let payload = new Uint8Array(outputArray.buffer, outputArray.byteOffset + HEADER_SIZE);
+  let compressedSize = Primitives.compress(array, inputBytes, payload);
+
+  // Add headers
+  outputArray.set(MAGIC_NUMBER);
+  let view = new DataView(outputArray.buffer);
+  view.setUint32(MAGIC_NUMBER.byteLength, inputBytes, true);
+
+  return new Uint8Array(outputArray.buffer, 0, HEADER_SIZE + compressedSize);
+}
+exports.compressFileContent = compressFileContent;
+
+function decompressFileContent(array, options = {}) {
+  let bytes = SharedAll.normalizeBufferArgs(array, options.bytes || null);
+  if (bytes < HEADER_SIZE) {
+    throw new LZError("decompress", "becauseLZNoHeader",
+      `Buffer is too short (no header) - Data: ${ options.path || array }`);
+  }
+
+  // Read headers
+  let expectMagicNumber = new DataView(array.buffer, 0, MAGIC_NUMBER.byteLength);
+  for (let i = 0; i < MAGIC_NUMBER.byteLength; ++i) {
+    if (expectMagicNumber.getUint8(i) != MAGIC_NUMBER[i]) {
+      throw new LZError("decompress", "becauseLZWrongMagicNumber",
+        `Invalid header (no magic number) - Data: ${ options.path || array }`);
+    }
+  }
+
+  let sizeBuf = new DataView(array.buffer, MAGIC_NUMBER.byteLength, BYTES_IN_SIZE_HEADER);
+  let expectDecompressedSize =
+    sizeBuf.getUint8(0) +
+    (sizeBuf.getUint8(1) << 8) +
+    (sizeBuf.getUint8(2) << 16) +
+    (sizeBuf.getUint8(3) << 24);
+  if (expectDecompressedSize == 0) {
+    // The underlying algorithm cannot handle a size of 0
+    return new Uint8Array(0);
+  }
+
+  // Prepare the input buffer
+  let inputData = new DataView(array.buffer, HEADER_SIZE);
+
+  // Prepare the output buffer
+  let outputBuffer = new Uint8Array(expectDecompressedSize);
+  let decompressedBytes = (new SharedAll.Type.size_t.implementation(0));
+
+  // Decompress
+  let success = Primitives.decompress(inputData, bytes - HEADER_SIZE,
+                                      outputBuffer, outputBuffer.byteLength,
+                                      decompressedBytes.address());
+  if (!success) {
+    throw new LZError("decompress", "becauseLZInvalidContent",
+      `Invalid content: Decompression stopped at ${decompressedBytes.value} - Data: ${ options.path || array }`);
+  }
+  return new Uint8Array(outputBuffer.buffer, outputBuffer.byteOffset, decompressedBytes.value);
+}
+exports.decompressFileContent = decompressFileContent;
+
+if (typeof Components != "undefined") {
+  this.Lz4 = {
+    compressFileContent: compressFileContent,
+    decompressFileContent: decompressFileContent
+  };
+}