1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/toolkit/components/workerlz4/lz4.js Wed Dec 31 06:09:35 2014 +0100
1.3 @@ -0,0 +1,136 @@
1.4 +/* This Source Code Form is subject to the terms of the Mozilla Public
1.5 + * License, v. 2.0. If a copy of the MPL was not distributed with this file,
1.6 + * You can obtain one at http://mozilla.org/MPL/2.0/. */
1.7 +
1.8 +"use strict";
1.9 +
1.10 +if (typeof Components != "undefined") {
1.11 + throw new Error("This file is meant to be loaded in a worker");
1.12 +}
1.13 +if (!module || !exports) {
1.14 + throw new Error("Please load this module with require()");
1.15 +}
1.16 +
1.17 +const SharedAll = require("resource://gre/modules/osfile/osfile_shared_allthreads.jsm");
1.18 +const Internals = require("resource://gre/modules/workers/lz4_internal.js");
1.19 +
1.20 +const MAGIC_NUMBER = new Uint8Array([109, 111, 122, 76, 122, 52, 48, 0]); // "mozLz4a\0"
1.21 +
1.22 +const BYTES_IN_SIZE_HEADER = ctypes.uint32_t.size;
1.23 +
1.24 +const HEADER_SIZE = MAGIC_NUMBER.byteLength + BYTES_IN_SIZE_HEADER;
1.25 +
1.26 +const EXPECTED_HEADER_TYPE = new ctypes.ArrayType(ctypes.uint8_t, HEADER_SIZE);
1.27 +const EXPECTED_SIZE_BUFFER_TYPE = new ctypes.ArrayType(ctypes.uint8_t, BYTES_IN_SIZE_HEADER);
1.28 +
1.29 +/**
1.30 + * An error during (de)compression
1.31 + *
1.32 + * @param {string} operation The name of the operation ("compress", "decompress")
1.33 + * @param {string} reason A reason to be used when matching errors. Must start
1.34 + * with "because", e.g. "becauseInvalidContent".
1.35 + * @param {string} message A human-readable message.
1.36 + */
1.37 +function LZError(operation, reason, message) {
1.38 + SharedAll.OSError.call(this);
1.39 + this.operation = operation;
1.40 + this[reason] = true;
1.41 + this.message = message;
1.42 +}
1.43 +LZError.prototype = Object.create(SharedAll.OSError);
1.44 +LZError.prototype.toString = function toString() {
1.45 + return this.message;
1.46 +};
1.47 +exports.Error = LZError;
1.48 +
1.49 +/**
1.50 + * Compress a block to a form suitable for writing to disk.
1.51 + *
1.52 + * Compatibility note: For the moment, we are basing our code on lz4
1.53 + * 1.3, which does not specify a *file* format. Therefore, we define
1.54 + * our own format. Once lz4 defines a complete file format, we will
1.55 + * migrate both |compressFileContent| and |decompressFileContent| to this file
1.56 + * format. For backwards-compatibility, |decompressFileContent| will however
1.57 + * keep the ability to decompress files provided with older versions of
1.58 + * |compressFileContent|.
1.59 + *
1.60 + * Compressed files have the following layout:
1.61 + *
1.62 + * | MAGIC_NUMBER (8 bytes) | content size (uint32_t, little endian) | content, as obtained from lz4_compress |
1.63 + *
1.64 + * @param {TypedArray|void*} buffer The buffer to write to the disk.
1.65 + * @param {object=} options An object that may contain the following fields:
1.66 + * - {number} bytes The number of bytes to read from |buffer|. If |buffer|
1.67 + * is an |ArrayBuffer|, |bytes| defaults to |buffer.byteLength|. If
1.68 + * |buffer| is a |void*|, |bytes| MUST be provided.
1.69 + * @return {Uint8Array} An array of bytes suitable for being written to the
1.70 + * disk.
1.71 + */
1.72 +function compressFileContent(array, options = {}) {
1.73 + // Prepare the output array
1.74 + let inputBytes;
1.75 + if (SharedAll.isTypedArray(array) && !(options && "bytes" in options)) {
1.76 + inputBytes = array.byteLength;
1.77 + } else if (options && options.bytes) {
1.78 + inputBytes = options.bytes;
1.79 + } else {
1.80 + throw new TypeError("compressFileContent requires a size");
1.81 + }
1.82 + let maxCompressedSize = Internals.maxCompressedSize(inputBytes);
1.83 + let outputArray = new Uint8Array(HEADER_SIZE + maxCompressedSize);
1.84 +
1.85 + // Compress to output array
1.86 + let payload = new Uint8Array(outputArray.buffer, outputArray.byteOffset + HEADER_SIZE);
1.87 + let compressedSize = Internals.compress(array, inputBytes, payload);
1.88 +
1.89 + // Add headers
1.90 + outputArray.set(MAGIC_NUMBER);
1.91 + let view = new DataView(outputArray.buffer);
1.92 + view.setUint32(MAGIC_NUMBER.byteLength, inputBytes, true);
1.93 +
1.94 + return new Uint8Array(outputArray.buffer, 0, HEADER_SIZE + compressedSize);
1.95 +}
1.96 +exports.compressFileContent = compressFileContent;
1.97 +
1.98 +function decompressFileContent(array, options = {}) {
1.99 + let {ptr, bytes} = SharedAll.normalizeToPointer(array, options.bytes || null);
1.100 + if (bytes < HEADER_SIZE) {
1.101 + throw new LZError("decompress", "becauseLZNoHeader", "Buffer is too short (no header)");
1.102 + }
1.103 +
1.104 + // Read headers
1.105 + let expectMagicNumber = ctypes.cast(ptr, EXPECTED_HEADER_TYPE.ptr).contents;
1.106 + for (let i = 0; i < MAGIC_NUMBER.byteLength; ++i) {
1.107 + if (expectMagicNumber[i] != MAGIC_NUMBER[i]) {
1.108 + throw new LZError("decompress", "becauseLZWrongMagicNumber", "Invalid header (no magic number");
1.109 + }
1.110 + }
1.111 +
1.112 + let sizeBuf =
1.113 + ctypes.cast(
1.114 + SharedAll.offsetBy(ptr, MAGIC_NUMBER.byteLength),
1.115 + EXPECTED_SIZE_BUFFER_TYPE.ptr).contents;
1.116 + let expectDecompressedSize =
1.117 + sizeBuf[0] + (sizeBuf[1] << 8) + (sizeBuf[2] << 16) + (sizeBuf[3] << 24);
1.118 + if (expectDecompressedSize == 0) {
1.119 + // The underlying algorithm cannot handle a size of 0
1.120 + return new Uint8Array(0);
1.121 + }
1.122 +
1.123 + // Prepare the input buffer
1.124 + let inputPtr = SharedAll.offsetBy(ptr, HEADER_SIZE);
1.125 +
1.126 + // Prepare the output buffer
1.127 + let outputBuffer = new Uint8Array(expectDecompressedSize);
1.128 + let decompressedBytes = (new SharedAll.Type.size_t.implementation(0));
1.129 +
1.130 + // Decompress
1.131 + let success = Internals.decompress(inputPtr, bytes - HEADER_SIZE,
1.132 + outputBuffer, outputBuffer.byteLength,
1.133 + decompressedBytes.address());
1.134 + if (!success) {
1.135 + throw new LZError("decompress", "becauseLZInvalidContent", "Invalid content:Decompression stopped at " + decompressedBytes.value);
1.136 + }
1.137 + return new Uint8Array(outputBuffer.buffer, outputBuffer.byteOffset, decompressedBytes.value);
1.138 +}
1.139 +exports.decompressFileContent = decompressFileContent;
