Untar works with example

examples/index.html

@@ -7,6 +7,7 @@
 <script src='../lib/utils.js'></script>
 <script src='../lib/header.js'></script>
 <script src='../lib/tar.js'></script>
+<script src='../lib/untar.js'></script>
 
 <script>
 (function () {
@@ -14,19 +15,35 @@
 
 	var Tar = require('tar'),
 		utils = require('utils'),
+		Untar = require('untar'),
 		tape = new Tar(),
 		out,
 		url,
 		base64;
 
+	function uint8ToString(buf) {
+		var i, length, out = '';
+		for (i = 0, length = buf.length; i < length; i += 1) {
+			out += String.fromCharCode(buf[i]);
+		}
+
+		return out;
+	}
+
 	out = tape.append('output.txt', 'This is test1!');
 	out = tape.append('dir/out.txt', 'This is test2! I changed up the directory');
 	out = tape.append('arr.txt', utils.stringToUint8('This is a Uint8Array!'));
 
+	Untar(out, function (header, data) {
+		var contents = uint8ToString(data);
+		console.log(header.fileName, contents);
+	});
+/*
 	base64 = utils.uint8ToBase64(out);
 
 	url = "data:application/tar;base64," + base64;
 	window.open(url);
+*/
 }());
 </script>
 </head>

lib/untar.js

@@ -0,0 +1,117 @@
+(function () {
+	"use strict";
+
+	var recordSize = 512;
+
+	function removePadding(buf) {
+		var text = '',
+			i, length;
+
+		for (i = 0, length = buf.length; i < buf.length; i += 1) {
+			text += String.fromCharCode(buf[i]);
+		}
+
+		return parseInt(text.replace(/^0*/, ''), 8) || 0;
+	}
+
+	function readString(buf) {
+		var text = '',
+			i, length;
+
+		for (i = 0, length = buf.length; i < length, buf[i] !== 0; i += 1) {
+			text += String.fromCharCode(buf[i]);
+		}
+
+		return text;
+	}
+
+	function doHeader(buf) {
+		var data = {}, offset = 0;
+
+		data.fileName = readString(buf.subarray(offset, offset + 100));
+		offset += 100;
+
+		data.fileMode = removePadding(buf.subarray(offset, offset + 8));
+		offset += 8;
+
+		data.uid = removePadding(buf.subarray(offset, offset + 8));
+		offset += 8;
+
+		data.gid = removePadding(buf.subarray(offset, offset + 8));
+		offset += 8;
+
+		data.fileSize = removePadding(buf.subarray(offset, offset + 12));
+		offset += 12;
+
+		data.mtime = removePadding(buf.subarray(offset, offset + 12));
+		offset += 12;
+
+		data.checksum = removePadding(buf.subarray(offset, offset + 8));
+		offset += 8;
+
+		data.type = removePadding(buf.subarray(offset, offset + 1));
+		offset += 1;
+
+		data.linkname = readString(buf.subarray(offset, offset + 100));
+		offset += 100;
+
+		data.ustar = readString(buf.subarray(offset, offset + 8));
+		if (/ustar/.test(data.ustar)) {
+			offset += 8;
+
+			data.owner = readString(buf.subarray(offset, offset + 32));
+			offset += 32;
+
+			data.group = readString(buf.subarray(offset, offset + 32));
+			offset += 32;
+
+			data.majorNumber = removePadding(buf.subarray(offset, offset + 8));
+			offset += 8;
+
+			data.minorNumber = removePadding(buf.subarray(offset, offset + 8));
+			offset += 8;
+
+			data.filenamePrefix = readString(buf.subarray(offset, offset + 155));
+		}
+
+		return data;
+	}
+
+	function doFile(buf, cb) {
+		var header, offset = 0, numBlocks, fileData;
+
+		header = doHeader(buf);
+
+		offset += recordSize;
+
+		numBlocks = Math.ceil(header.fileSize / recordSize);
+		fileData = buf.subarray(offset, offset + header.fileSize);
+
+		offset += numBlocks * recordSize;
+
+		cb(header, fileData, offset);
+	}
+
+	/*
+	 * Extract data from an input.
+	 * 
+	 * @param input- must be a buffer
+	 * @param opts- object of options
+	 * @param cb- callback to call on each file- params: header, fileData (uint8Array)
+	 */
+	function Untar (input, cb) {
+		var offset = 0;
+
+		while(input[offset]) {
+			doFile(input.subarray(offset), function (header, fileData, iOffset) {
+				offset += iOffset;
+
+				cb(header, fileData);
+			});
+		}
+	}
+
+	module.exports = Untar;
+
+	provide('untar', module.exports);
+}());