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untar.js
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untar.js
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/**
* untar.js
*
* Copyright(c) 2011 Google Inc.
*
* Reference Documentation:
*
* TAR format: http://www.gnu.org/software/automake/manual/tar/Standard.html
*/
// This file expects to be invoked as a Worker (see onmessage below).
importScripts('io.js');
importScripts('archive.js');
// Progress variables.
var currentFilename = "";
var currentFileNumber = 0;
var currentBytesUnarchivedInFile = 0;
var currentBytesUnarchived = 0;
var totalUncompressedBytesInArchive = 0;
var totalFilesInArchive = 0;
// Helper functions.
var info = function(str) {
postMessage(new bitjs.archive.UnarchiveInfoEvent(str));
};
var err = function(str) {
postMessage(new bitjs.archive.UnarchiveErrorEvent(str));
};
var postProgress = function() {
postMessage(new bitjs.archive.UnarchiveProgressEvent(
currentFilename,
currentFileNumber,
currentBytesUnarchivedInFile,
currentBytesUnarchived,
totalUncompressedBytesInArchive,
totalFilesInArchive));
};
// Removes all characters from the first zero-byte in the string onwards.
var readCleanString = function(bstr, numBytes) {
var str = bstr.readString(numBytes);
var zIndex = str.indexOf(String.fromCharCode(0));
return zIndex != -1 ? str.substr(0, zIndex) : str;
};
// takes a ByteStream and parses out the local file information
var TarLocalFile = function(bstream) {
this.isValid = false;
// Read in the header block
this.name = readCleanString(bstream, 100);
this.mode = readCleanString(bstream, 8);
this.uid = readCleanString(bstream, 8);
this.gid = readCleanString(bstream, 8);
this.size = parseInt(readCleanString(bstream, 12), 8);
this.mtime = readCleanString(bstream, 12);
this.chksum = readCleanString(bstream, 8);
this.typeflag = readCleanString(bstream, 1);
this.linkname = readCleanString(bstream, 100);
this.maybeMagic = readCleanString(bstream, 6);
if (this.maybeMagic == "ustar") {
this.version = readCleanString(bstream, 2);
this.uname = readCleanString(bstream, 32);
this.gname = readCleanString(bstream, 32);
this.devmajor = readCleanString(bstream, 8);
this.devminor = readCleanString(bstream, 8);
this.prefix = readCleanString(bstream, 155);
if (this.prefix.length) {
this.name = this.prefix + this.name;
}
bstream.readBytes(12); // 512 - 500
} else {
bstream.readBytes(255); // 512 - 257
}
// Done header, now rest of blocks are the file contents.
this.filename = this.name;
this.fileData = null;
info("Untarring file '" + this.filename + "'");
info(" size = " + this.size);
info(" typeflag = " + this.typeflag);
// A regular file.
if (this.typeflag == 0) {
info(" This is a regular file.");
var sizeInBytes = parseInt(this.size);
this.fileData = new Uint8Array(bstream.bytes.buffer, bstream.ptr, this.size);
if (this.name.length > 0 && this.size > 0 && this.fileData && this.fileData.buffer) {
this.isValid = true;
}
bstream.readBytes(this.size);
// Round up to 512-byte blocks.
var remaining = 512 - this.size % 512;
if (remaining > 0 && remaining < 512) {
bstream.readBytes(remaining);
}
} else if (this.typeflag == 5) {
info(" This is a directory.")
}
};
// Takes an ArrayBuffer of a tar file in
// returns null on error
// returns an array of DecompressedFile objects on success
var untar = function(arrayBuffer) {
currentFilename = "";
currentFileNumber = 0;
currentBytesUnarchivedInFile = 0;
currentBytesUnarchived = 0;
totalUncompressedBytesInArchive = 0;
totalFilesInArchive = 0;
postMessage(new bitjs.archive.UnarchiveStartEvent());
var bstream = new bitjs.io.ByteStream(arrayBuffer);
var localFiles = [];
// While we don't encounter an empty block, keep making TarLocalFiles.
while (bstream.peekNumber(4) != 0) {
var oneLocalFile = new TarLocalFile(bstream);
if (oneLocalFile && oneLocalFile.isValid) {
localFiles.push(oneLocalFile);
totalUncompressedBytesInArchive += oneLocalFile.size;
}
}
totalFilesInArchive = localFiles.length;
// got all local files, now sort them
localFiles.sort(function(a,b) {
// extract the number at the end of both filenames
var aname = a.filename;
var bname = b.filename;
var aindex = aname.length, bindex = bname.length;
// Find the last number character from the back of the filename.
while (aname[aindex-1] < '0' || aname[aindex-1] > '9') --aindex;
while (bname[bindex-1] < '0' || bname[bindex-1] > '9') --bindex;
// Find the first number character from the back of the filename
while (aname[aindex-1] >= '0' && aname[aindex-1] <= '9') --aindex;
while (bname[bindex-1] >= '0' && bname[bindex-1] <= '9') --bindex;
// parse them into numbers and return comparison
var anum = parseInt(aname.substr(aindex), 10),
bnum = parseInt(bname.substr(bindex), 10);
return anum - bnum;
});
// report # files and total length
if (localFiles.length > 0) {
postProgress();
}
// now do the shipping of each file
for (var i = 0; i < localFiles.length; ++i) {
var localfile = localFiles[i];
info("Sending file '" + localfile.filename + "' up");
// update progress
currentFilename = localfile.filename;
currentFileNumber = i;
currentBytesUnarchivedInFile = localfile.size;
currentBytesUnarchived += localfile.size;
postMessage(new bitjs.archive.UnarchiveExtractEvent(localfile));
postProgress();
}
postProgress();
postMessage(new bitjs.archive.UnarchiveFinishEvent());
};
// event.data.file has the ArrayBuffer.
onmessage = function(event) {
var ab = event.data.file;
untar(ab);
};