mbr

Documentation

Overview

Package mbr is a minimial implementation of Master Boot Record parsing and writing, implemented in support of GUID Partition Table parsing and writing. It is based on the UEFI Specification v2.6.

Index

• Constants
• func WriteProtectiveMBR(w io.Writer, blockSize, numBlocks uint64) error
• type MBR
  • func NewProtectiveMBR(numBlocks uint64) MBR
  • func ReadMBR(r io.Reader) (*MBR, error)
  • func (m *MBR) ReadFrom(r io.Reader) (int64, error)
  • func (m MBR) String() string
  • func (m *MBR) WriteTo(w io.Writer) (int64, error)
• type OSType
  • func (i OSType) String() string
• type PartitionRecord
• type Signature
  • func (i Signature) String() string

Constants

const MBRSize = 512

MBRSize is the size of an MBR record without logical block size padding

Functions

func WriteProtectiveMBR

func WriteProtectiveMBR(w io.Writer, blockSize, numBlocks uint64) error

WriteProtectiveMBR constructs and writes a protective MBR to w. It will only write the first block to w (that is, blockSize bytes).

Types

type MBR

type MBR struct {
	BootCode               [424]byte // 424 bytes should be enough for anybody...
	Pad                    [16]byte  // unnamed blank space in efi spec?
	UniqueMBRDiskSignature uint32
	Unknown                [2]byte
	PartitionRecord        [4]PartitionRecord
	Signature              Signature
}

MBR is a Go representation of a legacy Master Boot Record.

func NewProtectiveMBR

func NewProtectiveMBR(numBlocks uint64) MBR

NewProtectiveMBR constructs an MBR struct with fields conformant to the UEFI specification 2.6 "Protective MBR"

func ReadMBR

func ReadMBR(r io.Reader) (*MBR, error)

ReadMBR reads a MasterBootRecord from r.

func (*MBR) ReadFrom

func (m *MBR) ReadFrom(r io.Reader) (int64, error)

ReadFrom reads from the given io.Reader into the receiver MBR. If an error occurs the returned bytes read may be incorrect.

func (MBR) String

func (m MBR) String() string

func (*MBR) WriteTo

func (m *MBR) WriteTo(w io.Writer) (int64, error)

WriteTo implements the io.WriterTo interface for MBR. It writes the MBR to w in little endian as per the GPT specification.

type OSType

type OSType byte

OSType marks the partition type in an MBR Partition Record

const (
	FAT32               OSType = 0x0b
	UEFISystemPartition OSType = 0xEF
	GPTProtective       OSType = 0xEE
)

TODO(raggi): fill in other types and organize from: "Partition types" by Andries Brouwer: See "Links to UEFI-Related Documents" (http://uefi.org/uefi) under the heading "OS Type values used in the MBR disk layout".

func (OSType) String

func (i OSType) String() string

type PartitionRecord

type PartitionRecord struct {
	BootIndicator byte
	StartingCHS   [3]byte
	OSType        OSType
	EndingCHS     [3]byte
	StartingLBA   uint32
	SizeInLBA     uint32
}

PartitionRecord is a type representing a legacy MBR partition record

type Signature

type Signature uint16

Signature is an MBR Signature as two bytes in little endian.

const (
	// GPTSignature is the partition signature of a protective MBR partition
	GPTSignature Signature = 0xAA55
)

func (Signature) String

func (i Signature) String() string