The metadata stored by Android at the beginning of a "super" partition, which is what it calls a disk partition that holds one or more Dynamic Partitions. Dynamic Partitions do more or less the same thing that LVM does on Linux, allowing Android to map ranges of non-contiguous extents to a single logical device. This metadata holds that mapping.
This page hosts a formal specification of Android Dynamic Partitions metadata 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-structSee the usage examples in the JavaScript notes.
Parse structure from an ArrayBuffer:
var arrayBuffer = ...;
var data = new AndroidSuper(new KaitaiStream(arrayBuffer));
After that, one can get various attributes from the structure by accessing fields or properties like:
data.root // => get root
// 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(['exports', 'kaitai-struct/KaitaiStream'], factory);
} else if (typeof exports === 'object' && exports !== null && typeof exports.nodeType !== 'number') {
factory(exports, require('kaitai-struct/KaitaiStream'));
} else {
factory(root.AndroidSuper || (root.AndroidSuper = {}), root.KaitaiStream);
}
})(typeof self !== 'undefined' ? self : this, function (AndroidSuper_, KaitaiStream) {
/**
* The metadata stored by Android at the beginning of a "super" partition, which
* is what it calls a disk partition that holds one or more Dynamic Partitions.
* Dynamic Partitions do more or less the same thing that LVM does on Linux,
* allowing Android to map ranges of non-contiguous extents to a single logical
* device. This metadata holds that mapping.
* @see {@link https://source.android.com/docs/core/ota/dynamic_partitions|Source}
* @see {@link https://android.googlesource.com/platform/system/core/+/refs/tags/android-11.0.0_r8/fs_mgr/liblp/include/liblp/metadata_format.h|Source}
*/
var AndroidSuper = (function() {
function AndroidSuper(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root || this;
this._read();
}
AndroidSuper.prototype._read = function() {
}
var Geometry = AndroidSuper.Geometry = (function() {
function Geometry(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
Geometry.prototype._read = function() {
this.magic = this._io.readBytes(4);
if (!((KaitaiStream.byteArrayCompare(this.magic, new Uint8Array([103, 68, 108, 97])) == 0))) {
throw new KaitaiStream.ValidationNotEqualError(new Uint8Array([103, 68, 108, 97]), this.magic, this._io, "/types/geometry/seq/0");
}
this.structSize = this._io.readU4le();
this.checksum = this._io.readBytes(32);
this.metadataMaxSize = this._io.readU4le();
this.metadataSlotCount = this._io.readU4le();
this.logicalBlockSize = this._io.readU4le();
}
/**
* SHA-256 hash of struct_size bytes from beginning of geometry,
* calculated as if checksum were zeroed out
*/
return Geometry;
})();
var Metadata = AndroidSuper.Metadata = (function() {
Metadata.TableKind = Object.freeze({
PARTITIONS: 0,
EXTENTS: 1,
GROUPS: 2,
BLOCK_DEVICES: 3,
0: "PARTITIONS",
1: "EXTENTS",
2: "GROUPS",
3: "BLOCK_DEVICES",
});
function Metadata(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
Metadata.prototype._read = function() {
this.magic = this._io.readBytes(4);
if (!((KaitaiStream.byteArrayCompare(this.magic, new Uint8Array([48, 80, 76, 65])) == 0))) {
throw new KaitaiStream.ValidationNotEqualError(new Uint8Array([48, 80, 76, 65]), this.magic, this._io, "/types/metadata/seq/0");
}
this.majorVersion = this._io.readU2le();
this.minorVersion = this._io.readU2le();
this.headerSize = this._io.readU4le();
this.headerChecksum = this._io.readBytes(32);
this.tablesSize = this._io.readU4le();
this.tablesChecksum = this._io.readBytes(32);
this.partitions = new TableDescriptor(this._io, this, this._root, AndroidSuper.Metadata.TableKind.PARTITIONS);
this.extents = new TableDescriptor(this._io, this, this._root, AndroidSuper.Metadata.TableKind.EXTENTS);
this.groups = new TableDescriptor(this._io, this, this._root, AndroidSuper.Metadata.TableKind.GROUPS);
this.blockDevices = new TableDescriptor(this._io, this, this._root, AndroidSuper.Metadata.TableKind.BLOCK_DEVICES);
}
var BlockDevice = Metadata.BlockDevice = (function() {
function BlockDevice(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
BlockDevice.prototype._read = function() {
this.firstLogicalSector = this._io.readU8le();
this.alignment = this._io.readU4le();
this.alignmentOffset = this._io.readU4le();
this.size = this._io.readU8le();
this.partitionName = KaitaiStream.bytesToStr(KaitaiStream.bytesTerminate(this._io.readBytes(36), 0, false), "UTF-8");
this.flagSlotSuffixed = this._io.readBitsIntLe(1) != 0;
this.flagsReserved = this._io.readBitsIntLe(31);
}
return BlockDevice;
})();
var Extent = Metadata.Extent = (function() {
Extent.TargetType = Object.freeze({
LINEAR: 0,
ZERO: 1,
0: "LINEAR",
1: "ZERO",
});
function Extent(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
Extent.prototype._read = function() {
this.numSectors = this._io.readU8le();
this.targetType = this._io.readU4le();
this.targetData = this._io.readU8le();
this.targetSource = this._io.readU4le();
}
return Extent;
})();
var Group = Metadata.Group = (function() {
function Group(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
Group.prototype._read = function() {
this.name = KaitaiStream.bytesToStr(KaitaiStream.bytesTerminate(this._io.readBytes(36), 0, false), "UTF-8");
this.flagSlotSuffixed = this._io.readBitsIntLe(1) != 0;
this.flagsReserved = this._io.readBitsIntLe(31);
this._io.alignToByte();
this.maximumSize = this._io.readU8le();
}
return Group;
})();
var Partition = Metadata.Partition = (function() {
function Partition(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
Partition.prototype._read = function() {
this.name = KaitaiStream.bytesToStr(KaitaiStream.bytesTerminate(this._io.readBytes(36), 0, false), "UTF-8");
this.attrReadonly = this._io.readBitsIntLe(1) != 0;
this.attrSlotSuffixed = this._io.readBitsIntLe(1) != 0;
this.attrUpdated = this._io.readBitsIntLe(1) != 0;
this.attrDisabled = this._io.readBitsIntLe(1) != 0;
this.attrsReserved = this._io.readBitsIntLe(28);
this._io.alignToByte();
this.firstExtentIndex = this._io.readU4le();
this.numExtents = this._io.readU4le();
this.groupIndex = this._io.readU4le();
}
return Partition;
})();
var TableDescriptor = Metadata.TableDescriptor = (function() {
function TableDescriptor(_io, _parent, _root, kind) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this.kind = kind;
this._read();
}
TableDescriptor.prototype._read = function() {
this.offset = this._io.readU4le();
this.numEntries = this._io.readU4le();
this.entrySize = this._io.readU4le();
}
Object.defineProperty(TableDescriptor.prototype, 'table', {
get: function() {
if (this._m_table !== undefined)
return this._m_table;
var _pos = this._io.pos;
this._io.seek(this._parent.headerSize + this.offset);
this._raw__m_table = [];
this._m_table = [];
for (var i = 0; i < this.numEntries; i++) {
switch (this.kind) {
case AndroidSuper.Metadata.TableKind.BLOCK_DEVICES:
this._raw__m_table.push(this._io.readBytes(this.entrySize));
var _io__raw__m_table = new KaitaiStream(this._raw__m_table[i]);
this._m_table.push(new BlockDevice(_io__raw__m_table, this, this._root));
break;
case AndroidSuper.Metadata.TableKind.EXTENTS:
this._raw__m_table.push(this._io.readBytes(this.entrySize));
var _io__raw__m_table = new KaitaiStream(this._raw__m_table[i]);
this._m_table.push(new Extent(_io__raw__m_table, this, this._root));
break;
case AndroidSuper.Metadata.TableKind.GROUPS:
this._raw__m_table.push(this._io.readBytes(this.entrySize));
var _io__raw__m_table = new KaitaiStream(this._raw__m_table[i]);
this._m_table.push(new Group(_io__raw__m_table, this, this._root));
break;
case AndroidSuper.Metadata.TableKind.PARTITIONS:
this._raw__m_table.push(this._io.readBytes(this.entrySize));
var _io__raw__m_table = new KaitaiStream(this._raw__m_table[i]);
this._m_table.push(new Partition(_io__raw__m_table, this, this._root));
break;
default:
this._m_table.push(this._io.readBytes(this.entrySize));
break;
}
}
this._io.seek(_pos);
return this._m_table;
}
});
return TableDescriptor;
})();
/**
* SHA-256 hash of header_size bytes from beginning of metadata,
* calculated as if header_checksum were zeroed out
*/
/**
* SHA-256 hash of tables_size bytes from end of header
*/
return Metadata;
})();
var Root = AndroidSuper.Root = (function() {
function Root(_io, _parent, _root) {
this._io = _io;
this._parent = _parent;
this._root = _root;
this._read();
}
Root.prototype._read = function() {
this._raw_primaryGeometry = this._io.readBytes(4096);
var _io__raw_primaryGeometry = new KaitaiStream(this._raw_primaryGeometry);
this.primaryGeometry = new Geometry(_io__raw_primaryGeometry, this, this._root);
this._raw_backupGeometry = this._io.readBytes(4096);
var _io__raw_backupGeometry = new KaitaiStream(this._raw_backupGeometry);
this.backupGeometry = new Geometry(_io__raw_backupGeometry, this, this._root);
this._raw_primaryMetadata = [];
this.primaryMetadata = [];
for (var i = 0; i < this.primaryGeometry.metadataSlotCount; i++) {
this._raw_primaryMetadata.push(this._io.readBytes(this.primaryGeometry.metadataMaxSize));
var _io__raw_primaryMetadata = new KaitaiStream(this._raw_primaryMetadata[i]);
this.primaryMetadata.push(new Metadata(_io__raw_primaryMetadata, this, this._root));
}
this._raw_backupMetadata = [];
this.backupMetadata = [];
for (var i = 0; i < this.primaryGeometry.metadataSlotCount; i++) {
this._raw_backupMetadata.push(this._io.readBytes(this.primaryGeometry.metadataMaxSize));
var _io__raw_backupMetadata = new KaitaiStream(this._raw_backupMetadata[i]);
this.backupMetadata.push(new Metadata(_io__raw_backupMetadata, this, this._root));
}
}
return Root;
})();
Object.defineProperty(AndroidSuper.prototype, 'root', {
get: function() {
if (this._m_root !== undefined)
return this._m_root;
var _pos = this._io.pos;
this._io.seek(4096);
this._m_root = new Root(this._io, this, this._root);
this._io.seek(_pos);
return this._m_root;
}
});
return AndroidSuper;
})();
AndroidSuper_.AndroidSuper = AndroidSuper;
});