code before tests.. hm

test/1.txt

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+one

test/2.txt

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+two

test/3.txt

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+three

test/directory/1.txt

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+one

test/directory/2.txt

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+two

test/directory/3.txt

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+three

untar-worker.js

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+"use strict";
+
+onmessage = function(source) {
+	if (typeof source === "string") {
+		loadArrayBuffer(source).then(
+			untarBuffer,
+			function(err) { postMessage({ type: "error", data: err }); }
+		);
+	} else {
+		untarBuffer(source);
+	}
+};
+
+function loadArrayBuffer(uri) {
+	return new Promise(function(resolve, reject) {
+		try {
+			var request = new XMLHttpRequest();
+
+			request.addEventListener("progress", function(e) {
+				postMessage({ type: "loading", data: e });
+			});
+
+			request.addEventListener("load", function(e) {
+				resolve(request.response);
+			});
+
+			request.addEventListener("error", reject);
+			request.addEventListener("abort", reject);
+
+			request.open("GET", uri);
+			request.responseType = "arraybuffer";
+			request.send();
+		} catch (err) {
+			reject(err);
+		}
+	});
+}
+
+function untarBuffer(arrayBuffer) {
+	try {
+		var tarFileStream = new TarFileStream(arrayBuffer);
+		while (tarFileStream.hasNext()) {
+			var file = tarFileStream.next();
+
+			postMessage({ type: "extract", data: file }, [file.buffer]);
+		}
+
+		postMessage({ type: "complete" });
+		);
+	} catch (err) {
+		postMessage({ type: "error", data: err });
+	}
+}
+
+function TarFile() {
+
+}
+
+TarFile.prototype = {
+
+};
+
+function Stream(arrayBuffer) {
+	this._bufferView = new DataView(arrayBuffer);
+	this._position = 0;
+}
+
+Stream.prototype = {
+	readString: function(charCount) {
+		var charSize = 1;
+		var byteCount = charCount * charSize;
+
+		var charCodes = [];
+
+		for (var i = 0; i < charCount; ++i) {
+			var charCode = this._bufferView.getUint8(this.position() + (i * charSize));
+			if (charCode !== 0) {
+				charCodes.push(charCode);
+			} else {
+				break;
+			}
+		}
+
+		this.seek(byteCount);
+
+		return String.fromCharCode.apply(null, charCodes);
+	},
+
+	readBuffer: function(byteCount) {
+		return this._bufferView.buffer.slice(this._position, byteCount);
+	}
+
+	seek: function(byteCount) {
+		this._position += byteCount;
+	},
+
+	peekUint32: function() {
+		return this._bufferView.getUint32(this.position());
+	}
+
+	position: function(newpos) {
+		if (newpos === undefined) {
+			return this._position;
+		} else {
+			this._position = newpos;
+		}
+	}
+};
+
+function TarFileStream(arrayBuffer) {
+	this._stream = new Stream(arrayBuffer);
+}
+
+TarFileStream.prototype = {
+	hasNext: function() {
+		return this._stream.peekUint32() != 0;
+	},
+
+	next: function() {
+		var stream = this._stream;
+		var file = new TarFile();
+
+		var headerBeginPos = stream.position;
+		var dataBeginPos = headerBeginPos + 512;
+
+		// Read header
+		file.name = stream.readString(100);
+		file.mode = stream.readString(8);
+		file.uid = stream.readString(8);
+		file.gid = stream.readString(8);
+		file.size = parseInt(stream.readString(12), 8);
+		file.modificationTime = parseInt(stream.readString(12), 8);
+		file.checksum = stream.readString(8);
+		file.type = stream.readString(1);
+		file.linkname = stream.readString(1);
+		file.ustarFormat = stream.readString(6);
+
+		if (file.ustarFormat === "ustar") {
+			file.version = stream.readString(2);
+			file.uname = stream.readString(32);
+			file.gname = stream.readString(32);
+			file.devmajor = stream.readString(8);
+			file.devminor = stream.readString(8);
+			file.namePrefix = stream.readString(155);
+
+			if (file.namePrefix.length > 0) {
+				file.name = file.namePrefix + file.name;
+			}
+		}
+
+		stream.position(dataBeginPos);
+
+		// Normal file is either "\0" or 0.
+		if (file.type == 0 || file.type === "\0") {
+			file.buffer = stream.readBuffer(file.size);
+		} else if (file.type == 5) {
+			// Directory - should we do anything with this? Nope!
+		} else {
+			// We only care about real files, not symlinks.
+		}
+
+		// File data is padded to reach a 512 byte boundary; skip the padded bytes.
+		var bytesToSkipCount = 512 - file.size % 512;
+		stream.seek(bytesToSkipCount);
+
+		return file;
+	}
+};

untar.js

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+// var workerScriptUri is compiled in
+
+/**
+source	= ArrayBuffer or a url string. If an ArrayBuffer, it will be transfered to the web worker and will thus not be available in the window after.
+options	= {
+	onComplete,
+	onLoading, // When downloading the tar from a url.
+	onExtract,
+	onError
+}
+*/
+function untar(source, options) {
+	if (typeof Promise !== "function") {
+		throw new Error("Promise implementation not available in this environment.");
+	}
+
+	if (typeof Worker !== "function") {
+		throw new Error("Worker implementation not available in this environment.");
+	}
+
+	options = options || {};
+
+	function makeTarFile
+
+	return new Promise(function(resolve, reject) {
+		var noop = function() { };
+		var onComplete = options.onComplete || noop;
+		var onLoading = options.onProgress || noop;
+		var onExtract = options.onExtract || noop;
+		var onError = options.onError || noop;
+
+		var worker = new Worker(workerScriptUri);
+		var files = [];
+
+		worker.onmessage = function(message) {
+			switch (message.type) {
+				case "loading":
+					onLoading(message.data);
+					break;
+				case "extract":
+					var file = new TarFile(message.data);
+					files.push(file);
+					onExtract(file);
+					break;
+				case "complete":
+					onComplete(files);
+					resolve(files);
+					break;
+				case "error":
+					var error = message.data;
+					onError(error);
+					reject(error);
+					break;
+				default:
+					var error = new Error("Unknown message from worker.");
+					onError(error);
+					reject(error);
+					break;
+			}
+		};
+
+		// Don't transfer if source is a string. Only ArrayBuffer can be transfered.
+		worker.postMessage(source, (typeof source === "string" ? undefined : [source]));
+	});
+}
+
+function TarFile(orig) {
+	this._blobUrl = null;
+
+	for (p in orig) {
+		switch (p) {
+			case "buffer":
+				this.blob = new Blob([orig.buffer]);
+				break;
+			default:
+				this[p] = orig[p];
+				break;
+		}
+	}
+}
+
+TarFile.prototype = {
+	getObjectUrl: function() {
+		if (!this._blobUrl) {
+			this._blobUrl = URL.createObjectURL(this.blob);
+		}
+
+		return this._blobUrl;
+	}
+};