dd if=/dev/zero of=image.img bs=512 count=$(( 4 * 1024 * 2 ))
sudo losetup /dev/loop1 image.img
sudo pvcreate /dev/loop1
sudo vgcreate vg_test /dev/loop1
sudo lvcreate --name lv_test1 vg_test
sudo losetup -d /dev/loop1
This page hosts a formal specification of Logical Volume Manager version 2 using Kaitai Struct. This specification can be automatically translated into a variety of programming languages to get a parsing library.
All parsing code for Ruby generated by Kaitai Struct depends on the Ruby runtime library. You have to install it before you can parse data.
The Ruby runtime library can be installed from RubyGems:
gem install kaitai-structParse a local file and get structure in memory:
data = Lvm2.from_file("path/to/local/file.bin")
Or parse structure from a string of bytes:
bytes = "\x00\x01\x02..."
data = Lvm2.new(Kaitai::Struct::Stream.new(bytes))
After that, one can get various attributes from the structure by invoking getter methods like:
data.pv # => Physical volume
# This is a generated file! Please edit source .ksy file and use kaitai-struct-compiler to rebuild
require 'kaitai/struct/struct'
unless Gem::Version.new(Kaitai::Struct::VERSION) >= Gem::Version.new('0.9')
raise "Incompatible Kaitai Struct Ruby API: 0.9 or later is required, but you have #{Kaitai::Struct::VERSION}"
end
##
# ### Building a test file
#
# ```
# dd if=/dev/zero of=image.img bs=512 count=$(( 4 * 1024 * 2 ))
# sudo losetup /dev/loop1 image.img
# sudo pvcreate /dev/loop1
# sudo vgcreate vg_test /dev/loop1
# sudo lvcreate --name lv_test1 vg_test
# sudo losetup -d /dev/loop1
# ```
# @see https://github.com/libyal/libvslvm/blob/main/documentation/Logical%20Volume%20Manager%20(LVM)%20format.asciidoc Source
class Lvm2 < Kaitai::Struct::Struct
def initialize(_io, _parent = nil, _root = self)
super(_io, _parent, _root)
_read
end
def _read
@pv = PhysicalVolume.new(@_io, self, @_root)
self
end
class PhysicalVolume < Kaitai::Struct::Struct
def initialize(_io, _parent = nil, _root = self)
super(_io, _parent, _root)
_read
end
def _read
@empty_sector = @_io.read_bytes(_root.sector_size)
@label = Label.new(@_io, self, @_root)
self
end
class Label < Kaitai::Struct::Struct
def initialize(_io, _parent = nil, _root = self)
super(_io, _parent, _root)
_read
end
def _read
@label_header = LabelHeader.new(@_io, self, @_root)
@volume_header = VolumeHeader.new(@_io, self, @_root)
self
end
class LabelHeader < Kaitai::Struct::Struct
def initialize(_io, _parent = nil, _root = self)
super(_io, _parent, _root)
_read
end
def _read
@signature = @_io.read_bytes(8)
raise Kaitai::Struct::ValidationNotEqualError.new([76, 65, 66, 69, 76, 79, 78, 69].pack('C*'), signature, _io, "/types/physical_volume/types/label/types/label_header/seq/0") if not signature == [76, 65, 66, 69, 76, 79, 78, 69].pack('C*')
@sector_number = @_io.read_u8le
@checksum = @_io.read_u4le
@label_header_ = LabelHeader.new(@_io, self, @_root)
self
end
class LabelHeader < Kaitai::Struct::Struct
def initialize(_io, _parent = nil, _root = self)
super(_io, _parent, _root)
_read
end
def _read
@data_offset = @_io.read_u4le
@type_indicator = @_io.read_bytes(8)
raise Kaitai::Struct::ValidationNotEqualError.new([76, 86, 77, 50, 32, 48, 48, 49].pack('C*'), type_indicator, _io, "/types/physical_volume/types/label/types/label_header/types/label_header_/seq/1") if not type_indicator == [76, 86, 77, 50, 32, 48, 48, 49].pack('C*')
self
end
##
# The offset, in bytes, relative from the start of the physical volume label header where data is stored
attr_reader :data_offset
attr_reader :type_indicator
end
attr_reader :signature
##
# The sector number of the physical volume label header
attr_reader :sector_number
##
# CRC-32 for offset 20 to end of the physical volume label sector
attr_reader :checksum
attr_reader :label_header_
end
class VolumeHeader < Kaitai::Struct::Struct
def initialize(_io, _parent = nil, _root = self)
super(_io, _parent, _root)
_read
end
def _read
@id = (@_io.read_bytes(32)).force_encoding("ascii")
@size = @_io.read_u8le
@data_area_descriptors = []
i = 0
begin
_ = DataAreaDescriptor.new(@_io, self, @_root)
@data_area_descriptors << _
i += 1
end until ((_.size != 0) && (_.offset != 0))
@metadata_area_descriptors = []
i = 0
begin
_ = MetadataAreaDescriptor.new(@_io, self, @_root)
@metadata_area_descriptors << _
i += 1
end until ((_.size != 0) && (_.offset != 0))
self
end
class DataAreaDescriptor < Kaitai::Struct::Struct
def initialize(_io, _parent = nil, _root = self)
super(_io, _parent, _root)
_read
end
def _read
@offset = @_io.read_u8le
@size = @_io.read_u8le
self
end
def data
return @data unless @data.nil?
if size != 0
_pos = @_io.pos
@_io.seek(offset)
@data = (@_io.read_bytes(size)).force_encoding("ascii")
@_io.seek(_pos)
end
@data
end
##
# The offset, in bytes, relative from the start of the physical volume
attr_reader :offset
##
# Value in bytes. Can be 0. [yellow-background]*Does this represent all remaining available space?*
attr_reader :size
end
class MetadataAreaDescriptor < Kaitai::Struct::Struct
def initialize(_io, _parent = nil, _root = self)
super(_io, _parent, _root)
_read
end
def _read
@offset = @_io.read_u8le
@size = @_io.read_u8le
self
end
def data
return @data unless @data.nil?
if size != 0
_pos = @_io.pos
@_io.seek(offset)
@_raw_data = @_io.read_bytes(size)
_io__raw_data = Kaitai::Struct::Stream.new(@_raw_data)
@data = MetadataArea.new(_io__raw_data, self, @_root)
@_io.seek(_pos)
end
@data
end
##
# The offset, in bytes, relative from the start of the physical volume
attr_reader :offset
##
# Value in bytes
attr_reader :size
attr_reader :_raw_data
end
##
# According to `[REDHAT]` the metadata area is a circular buffer. New metadata is appended to the old metadata and then the pointer to the start of it is updated. The metadata area, therefore, can contain copies of older versions of the metadata.
class MetadataArea < Kaitai::Struct::Struct
def initialize(_io, _parent = nil, _root = self)
super(_io, _parent, _root)
_read
end
def _read
@header = MetadataAreaHeader.new(@_io, self, @_root)
self
end
class MetadataAreaHeader < Kaitai::Struct::Struct
def initialize(_io, _parent = nil, _root = self)
super(_io, _parent, _root)
_read
end
def _read
@checksum = MetadataAreaHeader.new(@_io, self, @_root)
@signature = @_io.read_bytes(16)
raise Kaitai::Struct::ValidationNotEqualError.new([32, 76, 86, 77, 50, 32, 120, 91, 53, 65, 37, 114, 48, 78, 42, 62].pack('C*'), signature, _io, "/types/physical_volume/types/label/types/volume_header/types/metadata_area/types/metadata_area_header/seq/1") if not signature == [32, 76, 86, 77, 50, 32, 120, 91, 53, 65, 37, 114, 48, 78, 42, 62].pack('C*')
@version = @_io.read_u4le
@metadata_area_offset = @_io.read_u8le
@metadata_area_size = @_io.read_u8le
@raw_location_descriptors = []
i = 0
begin
_ = RawLocationDescriptor.new(@_io, self, @_root)
@raw_location_descriptors << _
i += 1
end until ((_.offset != 0) && (_.size != 0) && (_.checksum != 0))
self
end
##
# The data area size can be 0. It is assumed it represents the remaining available data.
class RawLocationDescriptor < Kaitai::Struct::Struct
RAW_LOCATION_DESCRIPTOR_FLAGS = {
1 => :raw_location_descriptor_flags_raw_location_ignored,
}
I__RAW_LOCATION_DESCRIPTOR_FLAGS = RAW_LOCATION_DESCRIPTOR_FLAGS.invert
def initialize(_io, _parent = nil, _root = self)
super(_io, _parent, _root)
_read
end
def _read
@offset = @_io.read_u8le
@size = @_io.read_u8le
@checksum = @_io.read_u4le
@flags = Kaitai::Struct::Stream::resolve_enum(RAW_LOCATION_DESCRIPTOR_FLAGS, @_io.read_u4le)
self
end
##
# The data area offset, in bytes, relative from the start of the metadata area
attr_reader :offset
##
# data area size in bytes
attr_reader :size
##
# CRC-32 of *TODO (metadata?)*
attr_reader :checksum
attr_reader :flags
end
def metadata
return @metadata unless @metadata.nil?
_pos = @_io.pos
@_io.seek(metadata_area_offset)
@metadata = @_io.read_bytes(metadata_area_size)
@_io.seek(_pos)
@metadata
end
##
# CRC-32 for offset 4 to end of the metadata area header
attr_reader :checksum
attr_reader :signature
attr_reader :version
##
# The offset, in bytes, of the metadata area relative from the start of the physical volume
attr_reader :metadata_area_offset
attr_reader :metadata_area_size
##
# The last descriptor in the list is terminator and consists of 0-byte values.
attr_reader :raw_location_descriptors
end
attr_reader :header
end
##
# Contains a UUID stored as an ASCII string. The physical volume identifier can be used to uniquely identify a physical volume. The physical volume identifier is stored as: 9LBcEB7PQTGIlLI0KxrtzrynjuSL983W but is equivalent to its formatted variant: 9LBcEB-7PQT-GIlL-I0Kx-rtzr-ynju-SL983W, which is used in the metadata.
attr_reader :id
##
# Physical Volume size. Value in bytes
attr_reader :size
##
# The last descriptor in the list is terminator and consists of 0-byte values.
attr_reader :data_area_descriptors
attr_reader :metadata_area_descriptors
end
attr_reader :label_header
attr_reader :volume_header
end
attr_reader :empty_sector
attr_reader :label
end
def sector_size
return @sector_size unless @sector_size.nil?
@sector_size = 512
@sector_size
end
##
# Physical volume
attr_reader :pv
end