Android DTB/DTBO Partition: JavaScript parsing library

Format for Android DTB/DTBO partitions. It's kind of archive with dtb/dtbo files. Used only when there is a separate unique partition (dtb, dtbo) on an android device to organize device tree files. The format consists of a header with info about size and number of device tree entries and the entries themselves. This format description could be used to extract device tree entries from a partition images and decompile them with dtc (device tree compiler).

File extension

img

KS implementation details

License: CC0-1.0

This page hosts a formal specification of Android DTB/DTBO Partition using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.

Usage

Runtime 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

Code

See the usage examples in the JavaScript notes.

Parse structure from an ArrayBuffer:

var arrayBuffer = ...;
var data = new AndroidDto(new KaitaiStream(arrayBuffer));

After that, one can get various attributes from the structure by accessing fields or properties like:

data.header // => get header

JavaScript source code to parse Android DTB/DTBO Partition

AndroidDto.js

// 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.AndroidDto = factory(root.KaitaiStream);
  }
}(this, function (KaitaiStream) {
/**
 * Format for Android DTB/DTBO partitions. It's kind of archive with
 * dtb/dtbo files. Used only when there is a separate unique partition
 * (dtb, dtbo) on an android device to organize device tree files.
 * The format consists of a header with info about size and number
 * of device tree entries and the entries themselves. This format
 * description could be used to extract device tree entries from a
 * partition images and decompile them with dtc (device tree compiler).
 * @see {@link https://source.android.com/devices/architecture/dto/partitions|Source}
 * @see {@link https://android.googlesource.com/platform/system/libufdt/+/refs/tags/android-10.0.0_r47|Source}
 */

var AndroidDto = (function() {
  function AndroidDto(_io, _parent, _root) {
    this._io = _io;
    this._parent = _parent;
    this._root = _root || this;

    this._read();
  }
  AndroidDto.prototype._read = function() {
    this.header = new DtTableHeader(this._io, this, this._root);
    this.entries = new Array(this.header.dtEntryCount);
    for (var i = 0; i < this.header.dtEntryCount; i++) {
      this.entries[i] = new DtTableEntry(this._io, this, this._root);
    }
  }

  var DtTableHeader = AndroidDto.DtTableHeader = (function() {
    function DtTableHeader(_io, _parent, _root) {
      this._io = _io;
      this._parent = _parent;
      this._root = _root || this;

      this._read();
    }
    DtTableHeader.prototype._read = function() {
      this.magic = this._io.readBytes(4);
      if (!((KaitaiStream.byteArrayCompare(this.magic, [215, 183, 171, 30]) == 0))) {
        throw new KaitaiStream.ValidationNotEqualError([215, 183, 171, 30], this.magic, this._io, "/types/dt_table_header/seq/0");
      }
      this.totalSize = this._io.readU4be();
      this.headerSize = this._io.readU4be();
      this.dtEntrySize = this._io.readU4be();
      this.dtEntryCount = this._io.readU4be();
      this.dtEntriesOffset = this._io.readU4be();
      this.pageSize = this._io.readU4be();
      this.version = this._io.readU4be();
    }

    /**
     * includes dt_table_header + all dt_table_entry and all dtb/dtbo
     */

    /**
     * sizeof(dt_table_header)
     */

    /**
     * sizeof(dt_table_entry)
     */

    /**
     * number of dt_table_entry
     */

    /**
     * offset to the first dt_table_entry from head of dt_table_header
     */

    /**
     * flash page size
     */

    /**
     * DTBO image version
     */

    return DtTableHeader;
  })();

  var DtTableEntry = AndroidDto.DtTableEntry = (function() {
    function DtTableEntry(_io, _parent, _root) {
      this._io = _io;
      this._parent = _parent;
      this._root = _root || this;

      this._read();
    }
    DtTableEntry.prototype._read = function() {
      this.dtSize = this._io.readU4be();
      this.dtOffset = this._io.readU4be();
      this.id = this._io.readU4be();
      this.rev = this._io.readU4be();
      this.custom = new Array(4);
      for (var i = 0; i < 4; i++) {
        this.custom[i] = this._io.readU4be();
      }
    }

    /**
     * DTB/DTBO file
     */
    Object.defineProperty(DtTableEntry.prototype, 'body', {
      get: function() {
        if (this._m_body !== undefined)
          return this._m_body;
        var io = this._root._io;
        var _pos = io.pos;
        io.seek(this.dtOffset);
        this._m_body = io.readBytes(this.dtSize);
        io.seek(_pos);
        return this._m_body;
      }
    });

    /**
     * size of this entry
     */

    /**
     * offset from head of dt_table_header
     */

    /**
     * optional, must be zero if unused
     */

    /**
     * optional, must be zero if unused
     */

    /**
     * optional, must be zero if unused
     */

    return DtTableEntry;
  })();

  return AndroidDto;
})();
return AndroidDto;
}));