boot

package
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 Go to latest Published: Aug 18, 2025 License: BSD-3-Clause Imports: 13 Imported by: 7

Documentation

Overview

Package boot manipulates UEFI boot variables, and can identify and mount the volume referenced by a boot var.

Index

Constants

View Source 
const (
	BootUUID = "8be4df61-93ca-11d2-aa0d-00e098032b8c"
)

Variables

View Source 
var (
	Verbose bool

	ErrParse    = errors.New("parse error")
	ErrNotFound = errors.New("described device not found")

	// ErrUnimpl is returned when we do not implement the Device Path
	// Protocol entry type, because the Device Path Protocol is used for
	// more than boot entries. Some types aren't suitable for boot entries,
	// so a resolver doesn't make sense.
	//
	// There are probably others which can be used for boot entries, but are
	// not implemented simply because they have not been needed yet.
	ErrUnimpl = errors.New("not implemented")
)

Functions

func AllBootVars 

func AllBootVars() uefivars.EfiVars

AllBootVars returns all uefi vars that use the boot UUID and whose names begin with Boot.

These include:

  • BootXXXX (individual boot entries, XXXX is hex)
  • BootCurrent (marks whichever BootXXXX entry was used this boot)
  • BootOptionSupport
  • BootNext (can specify a particular entry to use next boot)
  • BootOrder (the order in which entries are tried)

func BootEntryFilter 

func BootEntryFilter(uuid, name string) bool

A VarNameFilter passing boot entries. These are a subset of the vars returned by BootVarFilter.

func BootVarFilter 

func BootVarFilter(uuid, name string) bool

A VarNameFilter passing boot-related vars. These are a superset of those returned by BootEntryFilter.

func IsBootEntry 

func IsBootEntry(e uefivars.EfiVar) bool

IsBootEntry returns true if the given var is a boot entry.

Types

type BootCurrentVar 

type BootCurrentVar struct {
	uefivars.EfiVar
	Current uint16
}

BootCurrentVar represents the UEFI BootCurrent var.

func BootCurrent 

func BootCurrent(vars uefivars.EfiVars) *BootCurrentVar

BootCurrent returns the BootCurrent var, if any, from the given list.

func ReadBootCurrent 

func ReadBootCurrent() *BootCurrentVar

ReadBootCurrent reads and returns the BootCurrent var.

type BootEntryVar 

type BootEntryVar struct {
	Number uint16 // from the var name
	EfiLoadOption
}

BootEntryVar is a boot entry. It will have the name BootXXXX where XXXX is hexadecimal.

func BootVar 

func BootVar(v uefivars.EfiVar) (b *BootEntryVar)

BootVar decodes an efivar as a boot entry. use IsBootEntry() to screen first.

func ReadBootVar 

func ReadBootVar(num uint16) (*BootEntryVar, error)

Gets BootXXXX var, if it exists

func ReadCurrentBootVar 

func ReadCurrentBootVar() (*BootEntryVar, error)

Reads BootCurrent, and from there gets the BootXXXX var referenced.

func (BootEntryVar) String 

func (b BootEntryVar) String() string

type BootEntryVars 

type BootEntryVars []*BootEntryVar

func AllBootEntryVars 

func AllBootEntryVars() BootEntryVars

AllBootEntryVars returns list of boot entries (BootXXXX). Note that BootCurrent, BootOptionSupport, BootNext, BootOrder, etc do not count as boot entries.

func BootEntries 

func BootEntries(vars uefivars.EfiVars) (bootvars BootEntryVars)

BootEntries takes a list of efi vars and parses any that are boot entries, returning a list of them.

type DppAcpiDevPath 

type DppAcpiDevPath struct {
	Hdr      EfiDevicePathProtocolHdr
	HID, UID []byte // both length 4; not sure of endianness
}

DppAcpiDevPath is an acpi device path.

func ParseDppAcpiDevPath 

func ParseDppAcpiDevPath(h EfiDevicePathProtocolHdr, b []byte) (*DppAcpiDevPath, error)

ParseDppAcpiDevPath parses input into a DppAcpiDevPath.

func (*DppAcpiDevPath) Header 

func (e *DppAcpiDevPath) Header() EfiDevicePathProtocolHdr

func (*DppAcpiDevPath) ProtoSubTypeStr 

func (e *DppAcpiDevPath) ProtoSubTypeStr() string

ProtoSubTypeStr returns the subtype as human readable.

func (*DppAcpiDevPath) Resolver 

func (e *DppAcpiDevPath) Resolver() (EfiPathSegmentResolver, error)

Resolver returns a nil EfiPathSegmentResolver and ErrUnimpl. See the comment associated with ErrUnimpl.

func (*DppAcpiDevPath) String 

func (e *DppAcpiDevPath) String() string

type DppAcpiExDevPath 

type DppAcpiExDevPath struct {
	Hdr                    EfiDevicePathProtocolHdr
	HID, UID, CID          []byte // all length 4; not sure of endianness
	HIDSTR, UIDSTR, CIDSTR string
}

DppAcpiExDevPath is an expanded dpp acpi device path.

func ParseDppAcpiExDevPath 

func ParseDppAcpiExDevPath(h EfiDevicePathProtocolHdr, b []byte) (*DppAcpiExDevPath, error)

ParseDppAcpiExDevPath parses input into a DppAcpiExDevPath.

func (*DppAcpiExDevPath) Header 

func (e *DppAcpiExDevPath) Header() EfiDevicePathProtocolHdr

func (*DppAcpiExDevPath) ProtoSubTypeStr 

func (e *DppAcpiExDevPath) ProtoSubTypeStr() string

ProtoSubTypeStr returns the subtype as human readable.

func (*DppAcpiExDevPath) Resolver 

func (e *DppAcpiExDevPath) Resolver() (EfiPathSegmentResolver, error)

Resolver returns a nil EfiPathSegmentResolver and ErrUnimpl. See the comment associated with ErrUnimpl.

func (*DppAcpiExDevPath) String 

func (e *DppAcpiExDevPath) String() string

type DppHwPci 

type DppHwPci struct {
	Hdr              EfiDevicePathProtocolHdr
	Function, Device uint8
}

DppHwPci is the struct in EfiDevicePathProtocol for DppHTypePCI

func ParseDppHwPci 

func ParseDppHwPci(h EfiDevicePathProtocolHdr, b []byte) (*DppHwPci, error)

Parses input into a DppHwPci struct.

func (*DppHwPci) Header 

func (e *DppHwPci) Header() EfiDevicePathProtocolHdr

func (*DppHwPci) ProtoSubTypeStr 

func (e *DppHwPci) ProtoSubTypeStr() string

ProtoSubTypeStr returns the subtype as human readable.

func (*DppHwPci) Resolver 

func (e *DppHwPci) Resolver() (EfiPathSegmentResolver, error)

Resolver returns a nil EfiPathSegmentResolver and ErrUnimpl. See the comment associated with ErrUnimpl.

func (*DppHwPci) String 

func (e *DppHwPci) String() string

type DppMediaFilePath 

type DppMediaFilePath struct {
	Hdr EfiDevicePathProtocolHdr

	PathNameDecoded string // stored as utf16
}

DppMediaFilePath is a struct in EfiDevicePathProtocol for DppMTypeFilePath.

If multiple are included in a load option, the docs say to concatenate them.

func ParseDppMediaFilePath 

func ParseDppMediaFilePath(h EfiDevicePathProtocolHdr, b []byte) (*DppMediaFilePath, error)

func (*DppMediaFilePath) Header 

func (e *DppMediaFilePath) Header() EfiDevicePathProtocolHdr

func (*DppMediaFilePath) ProtoSubTypeStr 

func (e *DppMediaFilePath) ProtoSubTypeStr() string

ProtoSubTypeStr returns the subtype as human readable.

func (*DppMediaFilePath) Resolver 

func (e *DppMediaFilePath) Resolver() (EfiPathSegmentResolver, error)

Resolver returns an EfiPathSegmentResolver decoding the DppMediaFilePath.

func (*DppMediaFilePath) String 

func (e *DppMediaFilePath) String() string

type DppMediaHDD 

type DppMediaHDD struct {
	Hdr EfiDevicePathProtocolHdr

	PartNum   uint32             // index into partition table for MBR or GPT; 0 indicates entire disk
	PartStart uint64             // starting LBA. only used for MBR?
	PartSize  uint64             // size in LB's. only used for MBR?
	PartSig   uefivars.MixedGUID // format determined by SigType below. unused bytes must be 0x0.
	PartFmt   uint8              // 0x01 for MBR, 0x02 for GPT
	SigType   uint8              // 0x00 - none; 0x01 - 32bit MBR sig (@ 0x1b8); 0x02 - GUID
}

DppMediaHDD is the struct in EfiDevicePathProtocol for DppMTypeHdd

func ParseDppMediaHdd 

func ParseDppMediaHdd(h EfiDevicePathProtocolHdr, b []byte) (*DppMediaHDD, error)

ParseDppMediaHdd parses input into a DppMediaHDD struct.

func (*DppMediaHDD) Header 

func (e *DppMediaHDD) Header() EfiDevicePathProtocolHdr

func (*DppMediaHDD) ProtoSubTypeStr 

func (e *DppMediaHDD) ProtoSubTypeStr() string

ProtoSubTypeStr returns the subtype as human readable.

func (*DppMediaHDD) Resolver 

func (e *DppMediaHDD) Resolver() (EfiPathSegmentResolver, error)

Resolver returns an EfiPathSegmentResolver which can find and mount the partition described by DppMediaHDD.

func (*DppMediaHDD) String 

func (e *DppMediaHDD) String() string

type DppMediaPIWGFF 

type DppMediaPIWGFF struct {
	Hdr EfiDevicePathProtocolHdr
	Ff  []byte
}

struct in EfiDevicePathProtocol for DppMTypePIWGFF

func ParseDppMediaPIWGFF 

func ParseDppMediaPIWGFF(h EfiDevicePathProtocolHdr, b []byte) (*DppMediaPIWGFF, error)

ParseDppMediaPIWGFF parses the input into a DppMediaPIWGFF.

func (*DppMediaPIWGFF) Header 

func (e *DppMediaPIWGFF) Header() EfiDevicePathProtocolHdr

func (*DppMediaPIWGFF) ProtoSubTypeStr 

func (e *DppMediaPIWGFF) ProtoSubTypeStr() string

ProtoSubTypeStr returns the subtype as human readable.

func (*DppMediaPIWGFF) Resolver 

func (e *DppMediaPIWGFF) Resolver() (EfiPathSegmentResolver, error)

Resolver returns a nil EfiPathSegmentResolver and ErrUnimpl. See the comment associated with ErrUnimpl.

func (*DppMediaPIWGFF) String 

func (e *DppMediaPIWGFF) String() string

type DppMediaPIWGFV 

type DppMediaPIWGFV struct {
	Hdr EfiDevicePathProtocolHdr
	Fv  []byte
}

struct in EfiDevicePathProtocol for DppMTypePIWGFV

func ParseDppMediaPIWGFV 

func ParseDppMediaPIWGFV(h EfiDevicePathProtocolHdr, b []byte) (*DppMediaPIWGFV, error)

ParseDppMediaPIWGFV parses input into a DppMediaPIWGFV.

func (*DppMediaPIWGFV) Header 

func (e *DppMediaPIWGFV) Header() EfiDevicePathProtocolHdr

func (*DppMediaPIWGFV) ProtoSubTypeStr 

func (e *DppMediaPIWGFV) ProtoSubTypeStr() string

ProtoSubTypeStr returns the subtype as human readable.

func (*DppMediaPIWGFV) Resolver 

func (e *DppMediaPIWGFV) Resolver() (EfiPathSegmentResolver, error)

Resolver returns a nil EfiPathSegmentResolver and ErrUnimpl. See the comment associated with ErrUnimpl.

func (*DppMediaPIWGFV) String 

func (e *DppMediaPIWGFV) String() string

type DppMsgATAPI 

type DppMsgATAPI struct {
	Hdr             EfiDevicePathProtocolHdr
	Primary, Master bool
	LUN             uint16
}

DppMsgATAPI is a struct describing an atapi dpp message. pg 293

func ParseDppMsgATAPI 

func ParseDppMsgATAPI(h EfiDevicePathProtocolHdr, b []byte) (*DppMsgATAPI, error)

ParseDppMsgATAPI parses input into a DppMsgATAPI.

func (*DppMsgATAPI) Header 

func (e *DppMsgATAPI) Header() EfiDevicePathProtocolHdr

func (*DppMsgATAPI) ProtoSubTypeStr 

func (e *DppMsgATAPI) ProtoSubTypeStr() string

ProtoSubTypeStr returns the subtype as human readable.

func (*DppMsgATAPI) Resolver 

func (e *DppMsgATAPI) Resolver() (EfiPathSegmentResolver, error)

Resolver returns a nil EfiPathSegmentResolver and ErrUnimpl. See the comment associated with ErrUnimpl.

func (*DppMsgATAPI) String 

func (e *DppMsgATAPI) String() string

type DppMsgMAC 

type DppMsgMAC struct {
	Hdr    EfiDevicePathProtocolHdr
	Mac    [32]byte // 0-padded
	IfType uint8    // RFC3232; seems ethernet is 6
}

DppMsgMAC contains a MAC address. pg 300

func ParseDppMsgMAC 

func ParseDppMsgMAC(h EfiDevicePathProtocolHdr, b []byte) (*DppMsgMAC, error)

ParseDppMsgMAC parses input into a DppMsgMAC.

func (*DppMsgMAC) Header 

func (e *DppMsgMAC) Header() EfiDevicePathProtocolHdr

func (*DppMsgMAC) ProtoSubTypeStr 

func (e *DppMsgMAC) ProtoSubTypeStr() string

ProtoSubTypeStr returns the subtype as human readable.

func (*DppMsgMAC) Resolver 

func (e *DppMsgMAC) Resolver() (EfiPathSegmentResolver, error)

Resolver returns a nil EfiPathSegmentResolver and ErrUnimpl. See the comment associated with ErrUnimpl.

func (*DppMsgMAC) String 

func (e *DppMsgMAC) String() string

type EfiDevPathEnd 

type EfiDevPathEnd struct {
	Hdr EfiDevicePathProtocolHdr
}

EfiDevPathEnd marks end of EfiDevicePathProtocol.

func (*EfiDevPathEnd) Header 

func (e *EfiDevPathEnd) Header() EfiDevicePathProtocolHdr

func (*EfiDevPathEnd) ProtoSubTypeStr 

func (e *EfiDevPathEnd) ProtoSubTypeStr() string

ProtoSubTypeStr returns the subtype as human readable.

func (*EfiDevPathEnd) Resolver 

func (e *EfiDevPathEnd) Resolver() (EfiPathSegmentResolver, error)

func (*EfiDevPathEnd) String 

func (e *EfiDevPathEnd) String() string

type EfiDevPathProtoSubType 

type EfiDevPathProtoSubType uint8

EfiDevPathProtoSubType is a dpp subtype in the spec. We only define media and end subtypes; others exist in spec.

type EfiDevPathProtoType 

type EfiDevPathProtoType uint8
const (
	DppTypeHw        EfiDevPathProtoType = iota + 1 // 0x01, pg 288
	DppTypeACPI                                     // 0x02, pg 290
	DppTypeMessaging                                // 0x03, pg 293
	DppTypeMedia                                    // 0x04, pg 319
	DppTypeBBS                                      // 0x05, pg 287
	DppTypeEnd       EfiDevPathProtoType = 0x7f
)

func (EfiDevPathProtoType) String 

func (e EfiDevPathProtoType) String() string

type EfiDevPathRaw 

type EfiDevPathRaw struct {
	Hdr EfiDevicePathProtocolHdr
	Raw []byte
}

func (*EfiDevPathRaw) Header 

func (e *EfiDevPathRaw) Header() EfiDevicePathProtocolHdr

func (*EfiDevPathRaw) ProtoSubTypeStr 

func (e *EfiDevPathRaw) ProtoSubTypeStr() string

ProtoSubTypeStr returns the subtype as human readable.

func (*EfiDevPathRaw) Resolver 

func (e *EfiDevPathRaw) Resolver() (EfiPathSegmentResolver, error)

func (*EfiDevPathRaw) String 

func (e *EfiDevPathRaw) String() string

type EfiDevicePathProtocol 

type EfiDevicePathProtocol interface {
	// Header returns the EfiDevicePathProtocolHdr.
	Header() EfiDevicePathProtocolHdr

	// ProtoSubTypeStr returns the subtype as human readable.
	ProtoSubTypeStr() string

	// String returns the path as human readable.
	String() string

	// Resolver returns an EfiPathSegmentResolver. In the case of filesystems,
	// this locates and mounts the device.
	Resolver() (EfiPathSegmentResolver, error)
}

EfiDevicePathProtocol identifies a device path.

type EfiDevicePathProtocolHdr 

type EfiDevicePathProtocolHdr struct {
	ProtoType    EfiDevPathProtoType
	ProtoSubType EfiDevPathProtoSubType
	Length       uint16
}

EfiDevicePathProtocolHdr is three one-byte fields that all DevicePathProtocol entries begin with. 

typedef struct _EFI_DEVICE_PATH_PROTOCOL {
    UINT8 Type;
    UINT8 SubType;
    UINT8 Length[2];
} EFI_DEVICE_PATH_PROTOCOL;

It seems that the only relevant Type (for booting) is media.

https://uefi.org/sites/default/files/resources/UEFI_Spec_2_8_A_Feb14.pdf pg 286 +

type EfiDevicePathProtocolList 

type EfiDevicePathProtocolList []EfiDevicePathProtocol

func ParseFilePathList 

func ParseFilePathList(in []byte) (EfiDevicePathProtocolList, error)

ParseFilePathList decodes a FilePathList as found in a boot var.

func (EfiDevicePathProtocolList) String 

func (list EfiDevicePathProtocolList) String() string

type EfiDppACPISubType 

type EfiDppACPISubType EfiDevPathProtoSubType

EfiDppACPISubType is the dpp subtype for ACPI. 

const (
	DppAcpiTypeDevPath EfiDppACPISubType = iota + 1
	DppAcpiTypeExpandedDevPath
	DppAcpiTypeADR
	DppAcpiTypeNVDIMM
)

func (EfiDppACPISubType) String 

func (e EfiDppACPISubType) String() string

type EfiDppEndSubType 

type EfiDppEndSubType EfiDevPathProtoSubType

EfiDppEndSubType defines the end of a device path protocol sequence. 

const (
	// DppTypeEnd, pg 287-288
	DppETypeEndStartNew EfiDppEndSubType = 0x01 // only for DppTypeHw?
	DppETypeEndEntire   EfiDppEndSubType = 0xff
)

func (EfiDppEndSubType) String 

func (e EfiDppEndSubType) String() string

type EfiDppHwSubType 

type EfiDppHwSubType EfiDevPathProtoSubType

EfiDppHwSubType is the dpp subtype for hardware. 

const (
	DppHTypePCI EfiDppHwSubType = iota + 1
	DppHTypePCCARD
	DppHTypeMMap
	DppHTypeVendor
	DppHTypeCtrl
	DppHTypeBMC
)

func (EfiDppHwSubType) String 

func (e EfiDppHwSubType) String() string

type EfiDppMediaSubType 

type EfiDppMediaSubType EfiDevPathProtoSubType
const (
	// DppTypeMedia, pg 319 +
	DppMTypeHdd      EfiDppMediaSubType = iota + 1 // 0x01
	DppMTypeCd                                     // 0x02
	DppMTypeVendor                                 // 0x03
	DppMTypeFilePath                               // 0x04 //p321
	DppMTypeMedia                                  // 0x05 //media protocol i.e. filesystem format??
	DppMTypePIWGFF                                 // 0x06
	DppMTypePIWGFV                                 // 0x07
	DppMTypeRelOff                                 // 0x08
	DppMTypeRAM                                    // 0x09
)

func (EfiDppMediaSubType) String 

func (e EfiDppMediaSubType) String() string

type EfiDppMsgSubType 

type EfiDppMsgSubType EfiDevPathProtoSubType
const (
	DppMsgTypeATAPI    EfiDppMsgSubType = iota + 1
	DppMsgTypeSCSI                      // 2
	DppMsgTypeFibreCh                   // 3
	DppMsgTypeFirewire                  // 4
	DppMsgTypeUSB                       // 5
	DppMsgTypeIIO                       // 6

	DppMsgTypeInfiniband // 9
	DppMsgTypeVendor     // 10 //uart flow control, sas are subtypes
	DppMsgTypeMAC        // 11
	DppMsgTypeIP4        // 12
	DppMsgTypeIP6        // 13
	DppMsgTypeUART       // 14
	DppMsgTypeUSBClass   // 15
	DppMsgTypeUSBWWID    // 16
	DppMsgTypeDevLU      // 17
	DppMsgTypeSATA       // 18
	DppMsgTypeISCSI      // 19
	DppMsgTypeVLAN       // 20

	DppMsgTypeSASEx  // 22
	DppMsgTypeNVME   // 23
	DppMsgTypeURI    // 24
	DppMsgTypeUFS    // 25
	DppMsgTypeSD     // 26
	DppMsgTypeBT     // 27
	DppMsgTypeWiFi   // 28
	DppMsgTypeeMMC   // 29
	DppMsgTypeBLE    // 30
	DppMsgTypeDNS    // 31
	DppMsgTypeNVDIMM // 32
	DppMsgTypeRest   // documented as 32, likely 33
)

func (EfiDppMsgSubType) String 

func (e EfiDppMsgSubType) String() string

type EfiLoadOption 

type EfiLoadOption struct {
	Attributes         uint32
	FilePathListLength uint16
	Description        string
	FilePathList       EfiDevicePathProtocolList
	OptionalData       []byte
}

EfiLoadOption defines the data struct used for vars such as BootXXXX.

As defined in UEFI spec v2.8A: 

typedef struct _EFI_LOAD_OPTION {
    UINT32 Attributes;
    UINT16 FilePathListLength;
    // CHAR16 Description[];
    // EFI_DEVICE_PATH_PROTOCOL FilePathList[];
    // UINT8 OptionalData[];
} EFI_LOAD_OPTION;

type EfiPathSegmentResolver 

type EfiPathSegmentResolver interface {
	// Returns description, does not require cleanup
	String() string

	// Mount fs, etc. You must call Cleanup() eventually.
	Resolve(suggestedBasePath string) (string, error)

	// For devices, returns BlockDev. Returns nil otherwise.
	BlockInfo() *block.BlockDev

	// For mounted devices, returns MountPoint. Returns nil otherwise.
	MntPoint() *mount.MountPoint

	// Unmount fs, free resources, etc
	Cleanup() error
}

type HddResolver 

type HddResolver struct {
	*block.BlockDev
	*mount.MountPoint
}

HddResolver can identify and mount a partition.

func (*HddResolver) BlockInfo 

func (r *HddResolver) BlockInfo() *block.BlockDev

func (*HddResolver) Cleanup 

func (r *HddResolver) Cleanup() error

func (*HddResolver) MntPoint 

func (r *HddResolver) MntPoint() *mount.MountPoint

func (*HddResolver) Resolve 

func (r *HddResolver) Resolve(basePath string) (string, error)

func (*HddResolver) String 

func (r *HddResolver) String() string

type PathResolver 

type PathResolver string

PathResolver outputs a file path.

func (*PathResolver) BlockInfo 

func (r *PathResolver) BlockInfo() *block.BlockDev

func (*PathResolver) Cleanup 

func (r *PathResolver) Cleanup() error

func (*PathResolver) MntPoint 

func (r *PathResolver) MntPoint() *mount.MountPoint

func (*PathResolver) Resolve 

func (r *PathResolver) Resolve(basePath string) (string, error)

func (*PathResolver) String 

func (r *PathResolver) String() string

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