MBR (Master Boot Record) partition table: PHP parsing library

MBR (Master Boot Record) partition table is a traditional way of MS-DOS to partition larger hard disc drives into distinct partitions.

This table is stored in the end of the boot sector (first sector) of the drive, after the bootstrap code. Original DOS 2.0 specification allowed only 4 partitions per disc, but DOS 3.2 introduced concept of "extended partitions", which work as nested extra "boot records" which are pointed to by original ("primary") partitions in MBR.

KS implementation details

License: CC0-1.0

This page hosts a formal specification of MBR (Master Boot Record) partition table using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.

PHP source code to parse MBR (Master Boot Record) partition table

MbrPartitionTable.php

<?php
// This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild

/**
 * MBR (Master Boot Record) partition table is a traditional way of
 * MS-DOS to partition larger hard disc drives into distinct
 * partitions.
 * 
 * This table is stored in the end of the boot sector (first sector) of
 * the drive, after the bootstrap code. Original DOS 2.0 specification
 * allowed only 4 partitions per disc, but DOS 3.2 introduced concept
 * of "extended partitions", which work as nested extra "boot records"
 * which are pointed to by original ("primary") partitions in MBR.
 */

class MbrPartitionTable extends \Kaitai\Struct\Struct {
    public function __construct(\Kaitai\Struct\Stream $_io, \Kaitai\Struct\Struct $_parent = null, \MbrPartitionTable $_root = null) {
        parent::__construct($_io, $_parent, $_root);
        $this->_read();
    }

    private function _read() {
        $this->_m_bootstrapCode = $this->_io->readBytes(446);
        $this->_m_partitions = [];
        $n = 4;
        for ($i = 0; $i < $n; $i++) {
            $this->_m_partitions[] = new \MbrPartitionTable\PartitionEntry($this->_io, $this, $this->_root);
        }
        $this->_m_bootSignature = $this->_io->ensureFixedContents("\x55\xAA");
    }
    protected $_m_bootstrapCode;
    protected $_m_partitions;
    protected $_m_bootSignature;
    public function bootstrapCode() { return $this->_m_bootstrapCode; }
    public function partitions() { return $this->_m_partitions; }
    public function bootSignature() { return $this->_m_bootSignature; }
}

namespace \MbrPartitionTable;

class PartitionEntry extends \Kaitai\Struct\Struct {
    public function __construct(\Kaitai\Struct\Stream $_io, \MbrPartitionTable $_parent = null, \MbrPartitionTable $_root = null) {
        parent::__construct($_io, $_parent, $_root);
        $this->_read();
    }

    private function _read() {
        $this->_m_status = $this->_io->readU1();
        $this->_m_chsStart = new \MbrPartitionTable\Chs($this->_io, $this, $this->_root);
        $this->_m_partitionType = $this->_io->readU1();
        $this->_m_chsEnd = new \MbrPartitionTable\Chs($this->_io, $this, $this->_root);
        $this->_m_lbaStart = $this->_io->readU4le();
        $this->_m_numSectors = $this->_io->readU4le();
    }
    protected $_m_status;
    protected $_m_chsStart;
    protected $_m_partitionType;
    protected $_m_chsEnd;
    protected $_m_lbaStart;
    protected $_m_numSectors;
    public function status() { return $this->_m_status; }
    public function chsStart() { return $this->_m_chsStart; }
    public function partitionType() { return $this->_m_partitionType; }
    public function chsEnd() { return $this->_m_chsEnd; }
    public function lbaStart() { return $this->_m_lbaStart; }
    public function numSectors() { return $this->_m_numSectors; }
}

namespace \MbrPartitionTable;

class Chs extends \Kaitai\Struct\Struct {
    public function __construct(\Kaitai\Struct\Stream $_io, \MbrPartitionTable\PartitionEntry $_parent = null, \MbrPartitionTable $_root = null) {
        parent::__construct($_io, $_parent, $_root);
        $this->_read();
    }

    private function _read() {
        $this->_m_head = $this->_io->readU1();
        $this->_m_b2 = $this->_io->readU1();
        $this->_m_b3 = $this->_io->readU1();
    }
    protected $_m_sector;
    public function sector() {
        if ($this->_m_sector !== null)
            return $this->_m_sector;
        $this->_m_sector = ($this->b2() & 63);
        return $this->_m_sector;
    }
    protected $_m_cylinder;
    public function cylinder() {
        if ($this->_m_cylinder !== null)
            return $this->_m_cylinder;
        $this->_m_cylinder = ($this->b3() + (($this->b2() & 192) << 2));
        return $this->_m_cylinder;
    }
    protected $_m_head;
    protected $_m_b2;
    protected $_m_b3;
    public function head() { return $this->_m_head; }
    public function b2() { return $this->_m_b2; }
    public function b3() { return $this->_m_b3; }
}