This page hosts a formal specification of VMWare Virtual Disk 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-struct
Parse a local file and get structure in memory:
data = VmwareVmdk.from_file("path/to/local/file.vmdk")
Or parse structure from a string of bytes:
bytes = "\x00\x01\x02..."
data = VmwareVmdk.new(Kaitai::Struct::Stream.new(bytes))
After that, one can get various attributes from the structure by invoking getter methods like:
data.size_max # => Maximum number of sectors in a given image file (capacity)
# 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
##
# @see https://github.com/libyal/libvmdk/blob/main/documentation/VMWare%20Virtual%20Disk%20Format%20(VMDK).asciidoc#41-file-header Source
class VmwareVmdk < Kaitai::Struct::Struct
COMPRESSION_METHODS = {
0 => :compression_methods_none,
1 => :compression_methods_deflate,
}
I__COMPRESSION_METHODS = COMPRESSION_METHODS.invert
def initialize(_io, _parent = nil, _root = self)
super(_io, _parent, _root)
_read
end
def _read
@magic = @_io.read_bytes(4)
raise Kaitai::Struct::ValidationNotEqualError.new([75, 68, 77, 86].pack('C*'), magic, _io, "/seq/0") if not magic == [75, 68, 77, 86].pack('C*')
@version = @_io.read_s4le
@flags = HeaderFlags.new(@_io, self, @_root)
@size_max = @_io.read_s8le
@size_grain = @_io.read_s8le
@start_descriptor = @_io.read_s8le
@size_descriptor = @_io.read_s8le
@num_grain_table_entries = @_io.read_s4le
@start_secondary_grain = @_io.read_s8le
@start_primary_grain = @_io.read_s8le
@size_metadata = @_io.read_s8le
@is_dirty = @_io.read_u1
@stuff = @_io.read_bytes(4)
@compression_method = Kaitai::Struct::Stream::resolve_enum(COMPRESSION_METHODS, @_io.read_u2le)
self
end
##
# @see https://github.com/libyal/libvmdk/blob/main/documentation/VMWare%20Virtual%20Disk%20Format%20(VMDK).asciidoc#411-flags Source
class HeaderFlags < Kaitai::Struct::Struct
def initialize(_io, _parent = nil, _root = self)
super(_io, _parent, _root)
_read
end
def _read
@reserved1 = @_io.read_bits_int_be(5)
@zeroed_grain_table_entry = @_io.read_bits_int_be(1) != 0
@use_secondary_grain_dir = @_io.read_bits_int_be(1) != 0
@valid_new_line_detection_test = @_io.read_bits_int_be(1) != 0
@_io.align_to_byte
@reserved2 = @_io.read_u1
@reserved3 = @_io.read_bits_int_be(6)
@has_metadata = @_io.read_bits_int_be(1) != 0
@has_compressed_grain = @_io.read_bits_int_be(1) != 0
@_io.align_to_byte
@reserved4 = @_io.read_u1
self
end
attr_reader :reserved1
attr_reader :zeroed_grain_table_entry
attr_reader :use_secondary_grain_dir
attr_reader :valid_new_line_detection_test
attr_reader :reserved2
attr_reader :reserved3
attr_reader :has_metadata
attr_reader :has_compressed_grain
attr_reader :reserved4
end
def len_sector
return @len_sector unless @len_sector.nil?
@len_sector = 512
@len_sector
end
def descriptor
return @descriptor unless @descriptor.nil?
_pos = @_io.pos
@_io.seek((start_descriptor * _root.len_sector))
@descriptor = @_io.read_bytes((size_descriptor * _root.len_sector))
@_io.seek(_pos)
@descriptor
end
def grain_primary
return @grain_primary unless @grain_primary.nil?
_pos = @_io.pos
@_io.seek((start_primary_grain * _root.len_sector))
@grain_primary = @_io.read_bytes((size_grain * _root.len_sector))
@_io.seek(_pos)
@grain_primary
end
def grain_secondary
return @grain_secondary unless @grain_secondary.nil?
_pos = @_io.pos
@_io.seek((start_secondary_grain * _root.len_sector))
@grain_secondary = @_io.read_bytes((size_grain * _root.len_sector))
@_io.seek(_pos)
@grain_secondary
end
attr_reader :magic
attr_reader :version
attr_reader :flags
##
# Maximum number of sectors in a given image file (capacity)
attr_reader :size_max
attr_reader :size_grain
##
# Embedded descriptor file start sector number (0 if not available)
attr_reader :start_descriptor
##
# Number of sectors that embedded descriptor file occupies
attr_reader :size_descriptor
##
# Number of grains table entries
attr_reader :num_grain_table_entries
##
# Secondary (backup) grain directory start sector number
attr_reader :start_secondary_grain
##
# Primary grain directory start sector number
attr_reader :start_primary_grain
attr_reader :size_metadata
attr_reader :is_dirty
attr_reader :stuff
attr_reader :compression_method
end