From Wikipedia:
"XAR (short for eXtensible ARchive format) is an open source file archiver and the archiver's file format. It was created within the OpenDarwin project and is used in macOS X 10.5 and up for software installation routines, as well as browser extensions in Safari 5.0 and up."
This page hosts a formal specification of XAR (eXtensible ARchive) using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
All parsing code for JavaScript generated by Kaitai Struct depends on the JavaScript runtime library. You have to install it before you can parse data.
The JavaScript runtime library is available at npm:
npm install kaitai-struct
See the usage examples in the JavaScript notes.
Parse structure from an ArrayBuffer:
var arrayBuffer = ...;
var data = new Xar(new KaitaiStream(arrayBuffer));
After that, one can get various attributes from the structure by accessing fields or properties like:
data.headerPrefix // => internal; access `_root.header` instead
// This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
(function (root, factory) {
if (typeof define === 'function' && define.amd) {
define(['kaitai-struct/KaitaiStream'], factory);
} else if (typeof module === 'object' && module.exports) {
module.exports = factory(require('kaitai-struct/KaitaiStream'));
} else {
root.Xar = factory(root.KaitaiStream);
}
}(typeof self !== 'undefined' ? self : this, function (KaitaiStream) {
/**
* From [Wikipedia](https://en.wikipedia.org/wiki/Xar_(archiver)):
*
* "XAR (short for eXtensible ARchive format) is an open source file archiver
* and the archiver's file format. It was created within the OpenDarwin project
* and is used in macOS X 10.5 and up for software installation routines, as
* well as browser extensions in Safari 5.0 and up."
* @see {@link https://github.com/mackyle/xar/wiki/xarformat|Source}
*/
var Xar = (function() {
Xar.ChecksumAlgorithmsApple = Object.freeze({
NONE: 0,
SHA1: 1,
MD5: 2,
SHA256: 3,
SHA512: 4,
0: "NONE",
1: "SHA1",
2: "MD5",
3: "SHA256",
4: "SHA512",
});
function Xar(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root || this;
this._read();
}
Xar.prototype._read = function() {
this.headerPrefix = new FileHeaderPrefix(this._io, this, this._root);
this._raw_header = this._io.readBytes((this.headerPrefix.lenHeader - 6));
var _io__raw_header = new KaitaiStream(this._raw_header);
this.header = new FileHeader(_io__raw_header, this, this._root);
this._raw__raw_toc = this._io.readBytes(this.header.lenTocCompressed);
this._raw_toc = KaitaiStream.processZlib(this._raw__raw_toc);
var _io__raw_toc = new KaitaiStream(this._raw_toc);
this.toc = new TocType(_io__raw_toc, this, this._root);
}
var FileHeaderPrefix = Xar.FileHeaderPrefix = (function() {
function FileHeaderPrefix(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root || this;
this._read();
}
FileHeaderPrefix.prototype._read = function() {
this.magic = this._io.readBytes(4);
if (!((KaitaiStream.byteArrayCompare(this.magic, [120, 97, 114, 33]) == 0))) {
throw new KaitaiStream.ValidationNotEqualError([120, 97, 114, 33], this.magic, this._io, "/types/file_header_prefix/seq/0");
}
this.lenHeader = this._io.readU2be();
}
/**
* internal; access `_root.header.len_header` instead
*/
return FileHeaderPrefix;
})();
var FileHeader = Xar.FileHeader = (function() {
function FileHeader(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root || this;
this._read();
}
FileHeader.prototype._read = function() {
this.version = this._io.readU2be();
if (!(this.version == 1)) {
throw new KaitaiStream.ValidationNotEqualError(1, this.version, this._io, "/types/file_header/seq/0");
}
this.lenTocCompressed = this._io.readU8be();
this.tocLengthUncompressed = this._io.readU8be();
this.checksumAlgorithmInt = this._io.readU4be();
if (this.hasChecksumAlgName) {
this.checksumAlgName = KaitaiStream.bytesToStr(KaitaiStream.bytesTerminate(this._io.readBytesFull(), 0, false), "UTF-8");
var _ = this.checksumAlgName;
if (!( ((_ != "") && (_ != "none")) )) {
throw new KaitaiStream.ValidationExprError(this.checksumAlgName, this._io, "/types/file_header/seq/4");
}
}
}
/**
* If it is not
*
* * `""` (empty string), indicating an unknown integer value (access
* `checksum_algorithm_int` for debugging purposes to find out
* what that value is), or
* * `"none"`, indicating that the TOC checksum is not provided (in that
* case, the `<checksum>` property or its `style` attribute should be
* missing, or the `style` attribute must be set to `"none"`),
*
* it must exactly match the `style` attribute value of the
* `<checksum>` property in the root node `<toc>`. See
* <https://github.com/mackyle/xar/blob/66d451d/xar/lib/archive.c#L345-L371>
* for reference.
*
* The `xar` (eXtensible ARchiver) program [uses OpenSSL's function
* `EVP_get_digestbyname`](
* https://github.com/mackyle/xar/blob/66d451d/xar/lib/archive.c#L328
* ) to verify this value (if it's not `""` or `"none"`, of course).
* So it's reasonable to assume that this can only have one of the values
* that OpenSSL recognizes.
*/
Object.defineProperty(FileHeader.prototype, 'checksumAlgorithmName', {
get: function() {
if (this._m_checksumAlgorithmName !== undefined)
return this._m_checksumAlgorithmName;
this._m_checksumAlgorithmName = (this.hasChecksumAlgName ? this.checksumAlgName : (this.checksumAlgorithmInt == Xar.ChecksumAlgorithmsApple.NONE ? "none" : (this.checksumAlgorithmInt == Xar.ChecksumAlgorithmsApple.SHA1 ? "sha1" : (this.checksumAlgorithmInt == Xar.ChecksumAlgorithmsApple.MD5 ? "md5" : (this.checksumAlgorithmInt == Xar.ChecksumAlgorithmsApple.SHA256 ? "sha256" : (this.checksumAlgorithmInt == Xar.ChecksumAlgorithmsApple.SHA512 ? "sha512" : ""))))));
return this._m_checksumAlgorithmName;
}
});
Object.defineProperty(FileHeader.prototype, 'hasChecksumAlgName', {
get: function() {
if (this._m_hasChecksumAlgName !== undefined)
return this._m_hasChecksumAlgName;
this._m_hasChecksumAlgName = ((this.checksumAlgorithmInt == this._root.checksumAlgorithmOther) && (this.lenHeader >= 32) && (KaitaiStream.mod(this.lenHeader, 4) == 0)) ;
return this._m_hasChecksumAlgName;
}
});
Object.defineProperty(FileHeader.prototype, 'lenHeader', {
get: function() {
if (this._m_lenHeader !== undefined)
return this._m_lenHeader;
this._m_lenHeader = this._root.headerPrefix.lenHeader;
return this._m_lenHeader;
}
});
/**
* internal; access `checksum_algorithm_name` instead
*/
/**
* internal; access `checksum_algorithm_name` instead
*/
return FileHeader;
})();
var TocType = Xar.TocType = (function() {
function TocType(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root || this;
this._read();
}
TocType.prototype._read = function() {
this.xmlString = KaitaiStream.bytesToStr(this._io.readBytesFull(), "UTF-8");
}
return TocType;
})();
/**
* @see {@link https://github.com/mackyle/xar/blob/66d451d/xar/include/xar.h.in#L85|Source}
*/
Object.defineProperty(Xar.prototype, 'checksumAlgorithmOther', {
get: function() {
if (this._m_checksumAlgorithmOther !== undefined)
return this._m_checksumAlgorithmOther;
this._m_checksumAlgorithmOther = 3;
return this._m_checksumAlgorithmOther;
}
});
/**
* internal; access `_root.header` instead
*/
/**
* zlib compressed XML further describing the content of the archive
*/
return Xar;
})();
return Xar;
}));