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module Msf
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module Util
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module WindowsRegistry
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  #
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  # This utility class processes binary Windows registry key. It is usually
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  # used when only offline processing is possible and [MS-RRP] BaseRegSaveKey()
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  # is used to save a registry key to a file.
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  #
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  # It also includes helpers for specific registry keys (SAM, SECURITY) through
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  # the `name` key word argument during instantiation.
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  #
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  class RegistryParser
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    # Constants
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    ROOT_KEY        = 0x2c
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    REG_NONE        = 0x00
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    REG_SZ          = 0x01
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    REG_EXPAND_SZ   = 0x02
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    REG_BINARY      = 0x03
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    REG_DWORD       = 0x04
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    REG_MULTISZ     = 0x07
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    REG_QWORD       = 0x0b
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    # Magic strings
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    # REGF magic value: 'regf'
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    REGF_MAGIC = 0x72656766
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    # NK magic value: 'nk'
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    NK_MAGIC = 0x6E6B
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    # VK magic value: 'vk'
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    VK_MAGIC = 0x766B
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    # LF magic value: 'lf'
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    LF_MAGIC = 0x6C66
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    # LH magic value: 'lh'
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    LH_MAGIC = 0x6C68
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    # RI magic value: 'ri'
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    RI_MAGIC = 0x7269
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    # SK magic value: 'sk'
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    SK_MAGIC = 0x7269
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    # HBIN magic value: 'hbin'
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    HBIN_MAGIC = 0x6862696E
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    #
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    # [Windows NT Registry File (REGF) format specification](https://github.com/libyal/libregf/blob/main/documentation/Windows%20NT%20Registry%20File%20(REGF)%20format.asciidoc)
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    #
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    # Registry File Header
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    class RegRegf < BinData::Record
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      endian :little
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      bit32  :magic, initial_value: REGF_MAGIC
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      uint32 :sequence1
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      uint32 :sequence2
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      uint64 :last_change
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      uint32 :major_version
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      uint32 :minor_version
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      uint32 :unknown1
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      uint32 :unknown2
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      uint32 :offset_first_record
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      uint32 :data_size
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      uint32 :unknown3
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      string :name, length: 48
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      string :remaining1, length: 411
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      uint32 :checksum, initial_value: 0xFFFFFFFF
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      string :remaining2, length: 3585
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    end
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    # Named key
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    class RegNk < BinData::Record
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      endian :little
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      bit16  :magic, initial_value: NK_MAGIC
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      uint16 :nk_type
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      uint64 :last_change
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      uint32 :unknown
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      int32  :offset_parent
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      uint32 :num_sub_keys
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      uint32 :unknown2
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      int32  :offset_sub_key_lf
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      uint32 :unknown3
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      uint32 :num_values
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      int32  :offset_value_list
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      int32  :offset_sk_rRecord
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      int32  :offset_class_name
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      string :unused, length: 20
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      uint16 :name_length, initial_value: -> { self.key_name.length }
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      uint16 :class_name_length
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      string :key_name, read_length: -> { self.name_length }
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    end
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    # Value key
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    class RegVk < BinData::Record
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      endian :little
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      bit16  :magic, initial_value: VK_MAGIC
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      uint16 :name_length, initial_value: -> { self.name.length }
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      int32  :data_len
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      uint32 :offset_data
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      uint32 :value_type
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      uint16 :flag
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      uint16 :unused
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      string :name, read_length: -> { self.name_length }
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    end
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    class RegHash < BinData::Record
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      endian :little
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      int32  :offset_nk
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      string :key_name, length: 4
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    end
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    class RegHash2 < BinData::Record
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      endian :little
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      int32  :offset_nk
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    end
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    # Sub keys list (LF)
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    class RegLf < BinData::Record
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      endian :little
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      bit16  :magic, initial_value: LF_MAGIC
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      uint16 :num_keys
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      array  :hash_records, type: :reg_hash, read_until: -> { index == (self.num_keys - 1) }
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    end
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    # Sub keys list (LH)
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    class RegLh < BinData::Record
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      endian :little
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      bit16  :magic, initial_value: LH_MAGIC
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      uint16 :num_keys
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      array  :hash_records, type: :reg_hash, read_until: -> { index == (self.num_keys - 1) }
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    end
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    # Sub keys list (RI)
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    class RegRi < BinData::Record
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      endian :little
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      bit16  :magic, initial_value: RI_MAGIC
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      uint16 :num_keys
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      array  :hash_records, type: :reg_hash2, read_until: -> { index == (self.num_keys - 1) }
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    end
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    # Security key
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    class RegSk < BinData::Record
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      endian :little
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      bit16  :magic, initial_value: SK_MAGIC
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      uint16 :unused
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      int32  :offset_previous_sk
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      int32  :offset_next_sk
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      uint32 :usage_counter
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      uint32 :size_sk, initial_length: -> { self.data.do_num_bytes }
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      string :data, read_length: -> { self.size_sk }
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    end
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    # Hive bin cell
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    class RegHbinBlock < BinData::Record
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      attr_reader :record_type
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      endian :little
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      int32  :data_block_size#, byte_align: 4
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      choice :data, selection: -> { @obj.parent.record_type } do
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        reg_nk 'nk'
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        reg_vk 'vk'
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        reg_lf 'lf'
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        reg_lh 'lh'
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        reg_ri 'ri'
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        reg_sk 'sk'
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        string :default, read_length: -> { self.data_block_size == 0 ? 0 : self.data_block_size.abs - 4 }
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      end
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      string :unknown, length: -> { self.data_block_size.abs - self.data.do_num_bytes - 4 }
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      def do_read(io)
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        io.with_readahead do
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          io.seekbytes(4)
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          @record_type = io.readbytes(2)
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        end
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        super(io)
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      end
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    end
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    # Hive bin
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    class RegHbin < BinData::Record
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      endian :little
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      bit32  :magic, initial_value: HBIN_MAGIC
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      uint32 :offset_first_hbin
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      uint32 :hbin_size
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      string :unknown, length: 16
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      uint32 :offset_next_hbin # hbin_size
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      array  :reg_hbin_blocks, type: :reg_hbin_block, read_until: :eof
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    end
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    # @param hive_data [String] The binary registry data
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    # @param name [Symbol] The key name to add specific helpers. Only `:sam`
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    # @param root [String] The root key and subkey corresponding to the hive_data
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    #   and `:security` are supported at the moment.
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    def initialize(hive_data, name: nil, root: nil)
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      @hive_data = hive_data.b
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      @regf = RegRegf.read(@hive_data)
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      @root_key_block = find_root_key
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      @root = root
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      @root << '\\' unless root.end_with?('\\')
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      case name
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      when :sam
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        require_relative 'sam'
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        extend Sam
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      when :security
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        require_relative 'security'
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        extend Security
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      else
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        wlog("[Msf::Util::WindowsRegistry::RegistryParser] Unknown :name argument: #{name}") unless name.blank?
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      end
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    end
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    # Returns the ROOT key as a block
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    #
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    # @return [RegHbinBlock] The ROOT key block
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    # @raise [StandardError] If an error occurs during parsing or if the ROOT
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    #   key is not found
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    def find_root_key
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      reg_hbin = nil
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      # Split the data in 4096-bytes blocks
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      @hive_data.unpack('a4096' * (@hive_data.size / 4096)).each do |data|
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        next unless data[0,4] == 'hbin'
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        reg_hbin = RegHbin.read(data)
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        root_key_block = reg_hbin.reg_hbin_blocks.find do |block|
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          block.data.respond_to?(:magic) && block.data.magic == NK_MAGIC && block.data.nk_type == ROOT_KEY
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        end
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        return root_key_block if root_key_block
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      rescue IOError
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        raise StandardError, 'Cannot parse the RegHbin structure'
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      end
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      raise StandardError, 'Cannot find the RootKey' unless reg_hbin
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    end
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    # Returns the type and the data of a given key/value pair
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    #
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    # @param reg_key [String] The registry key
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    # @param reg_value [String] The value in the registry key
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    # @return [Array] The type (Integer) and data (String) of the given
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    #   key/value as the first and second element of an array, respectively
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    def get_value(reg_key, reg_value = nil)
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      reg_key = find_key(reg_key)
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      return nil unless reg_key
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      if reg_key.data.num_values > 0
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        value_list = get_value_blocks(reg_key.data.offset_value_list, reg_key.data.num_values + 1)
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        value_list.each do |value|
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          if value.data.name == reg_value.to_s ||
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             reg_value.nil? && value.data.flag <= 0
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            return value.data.value_type.to_i, get_value_data(value.data)
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          end
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        end
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      end
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      nil
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    end
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    # Search for a given key from the ROOT key and returns it as a block
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    #
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    # @param key [String] The registry key to look for
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    # @return [RegHbinBlock, nil] The key, if found, nil otherwise
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    def find_key(key)
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      # Let's strip '\' from the beginning, except for the case of
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      # only asking for the root node
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      key = key[1..-1] if key[0] == '\\' && key.size > 1
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      parent_key = @root_key_block
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      if key.size > 0 && key[0] != '\\'
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        key.split('\\').each do |sub_key|
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          res = find_sub_key(parent_key, sub_key)
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          return nil unless res
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          parent_key = res
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        end
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      end
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      parent_key
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    end
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    # Search for a sub key from a given base key
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    #
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    # @param parent_key [String] The base key
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    # @param sub_key [String] The sub key to look for under parent_key
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    # @return [RegHbinBlock, nil] The key, if found, nil otherwise
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    # @raise [ArgumentError] If the parent key is not a NK record
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    def find_sub_key(parent_key, sub_key)
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      unless parent_key&.data&.magic == NK_MAGIC
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        raise ArgumentError, "find_sub_key: parent key must be a NK record"
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      end
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      block = get_block(parent_key.data.offset_sub_key_lf)
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      blocks = []
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      if block.data.magic == RI_MAGIC
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        # ri points to lf/lh records, so we consolidate them in the main blocks array
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        block.data.hash_records.each do |hash_record|
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          blocks << get_block(hash_record.offset_nk)
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        end
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      else
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        blocks << block
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      end
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      # Let's search the hash records for the name
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      blocks.each do |block|
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        block.data.hash_records.each do |hash_record|
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          res = get_offset(block.data.magic, hash_record, sub_key)
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          if res
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            nk = get_block(res)
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            return nk if nk.data.key_name == sub_key
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          end
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        end
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      end
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      nil
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    end
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    # Returns a registry block given its offset
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    #
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    # @param offset [String] The offset of the block
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    # @return [RegHbinBlock] The registry block
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    def get_block(offset)
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      RegHbinBlock.read(@hive_data[4096+offset..-1])
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    end
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    # Returns the offset of a given subkey in a hash record
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    #
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    # @param magic [Integer] The signtaure (MAGIC)
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    # @param hash_rec [Integer] The hash record
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    # @param key [Integer] The subkey to look for
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    # @return [Integer] The offset of the subkey
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    def get_offset(magic, hash_rec, key)
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      case magic
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      when LF_MAGIC
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        if hash_rec.key_name.gsub(/(^\x00*)|(\x00*$)/, '') == key[0,4]
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          return hash_rec.offset_nk
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        end
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      when LH_MAGIC
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        if hash_rec.key_name.unpack('L<').first == get_lh_hash(key)
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          return hash_rec.offset_nk
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        end
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      when RI_MAGIC
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        # Special case here, don't know exactly why, an RI pointing to a NK
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        offset = hash_rec.offset_nk
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        nk = get_block(offset)
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        return offset if nk.key_name == key
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      else
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        raise ArgumentError, "Unknown magic: #{magic}"
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      end
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    end
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    # Returns the hash of a LH subkey
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    # from http://www.sentinelchicken.com/data/TheWindowsNTRegistryFileFormat.pdf (Appendix C)
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    #
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    # @param key [Integer] The LH subkey
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    # @return [Integer] The hash
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    def get_lh_hash(key)
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      res = 0
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      key.upcase.bytes do |byte|
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        res *= 37
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        res += byte.ord
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      end
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      return res % 0x100000000
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    end
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    # Returns a list of `count``value blocks from the offsets located at `offset`
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    #
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    # @param offset [Integer] The offset where the offsets of each value is located
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    # @param count [Integer] The number of value blocks to retrieve
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    # @return [Array] An array of registry blocks
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    def get_value_blocks(offset, count)
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      value_list = []
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      res = []
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      count.times do |i|
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        value_list << @hive_data[4096+offset+i*4, 4].unpack('l<').first
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      end
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      value_list.each do |value_offset|
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        if value_offset > 0
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          block = get_block(value_offset)
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          res << block
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        end
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      end
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      return res
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    end
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    # Returns the data of a VK record value
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    #
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    # @param record [String] The VK record
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    # @return [String] The data
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    # @raise [ArgumentError] If the parent key is not a VK record
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    def get_value_data(record)
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      unless record&.magic == VK_MAGIC
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        raise ArgumentError, "get_value_data: record must be a VK record"
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      end
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      return '' if record.data_len == 0
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      # if DataLen < 5 the value itself is stored in the Offset field
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      return record.offset_data.to_binary_s if record.data_len < 0
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      return self.get_data(record.offset_data, record.data_len + 4)
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    end
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    # Returns the data at a given offset from the end of the header in the raw
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    # hive binary.
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    #
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    # @param offset [String] The offset from the end of the header
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    # @param count [Integer] The size of the data. Since the 4 first bytes are
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    #   ignored, the data returned will be (count - 4) long.
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    # @return [String] The resulting data
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    def get_data(offset, count)
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      @hive_data[4096+offset, count][4..-1]
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    end
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    # Enumerate the subkey names under `key`
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    #
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    # @param key [String] The parent key from which to enumerate
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    # @return [Array] The key names
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    # @raise [ArgumentError] If the parent key is not a NK record
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    def enum_key(key)
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      parent_key = find_key(key)
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      return nil unless parent_key
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      unless parent_key.data&.magic == NK_MAGIC
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        raise ArgumentError, "enum_key: parent key must be a NK record"
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      end
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      block = get_block(parent_key.data.offset_sub_key_lf)
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      records = []
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      if block.data.magic == RI_MAGIC
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        # ri points to lf/lh records, so we consolidate the hash records in the main records array
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        block.data.hash_records.each do |hash_record|
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          record = get_block(hash_record.offset_nk)
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          records.concat(record.data.hash_records)
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        end
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      else
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        records.concat(block.data.hash_records)
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      end
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      records.map do |reg_hash|
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        nk = get_block(reg_hash.offset_nk)
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        nk.data.key_name.to_s.b
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      end
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    end
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    # Enumerate the subkey values under `key`
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    #
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    # @param key [String] The parent key from which to enumerate
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    # @return [Array] The key values
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    # @raise [ArgumentError] If the parent key is not a NK record
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    def enum_values(key)
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      key_obj = find_key(key)
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      return nil unless key_obj
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      unless key_obj&.data&.magic == NK_MAGIC
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        raise ArgumentError, "enum_values: key must be a NK record"
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      end
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      res = []
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      value_list = get_value_blocks(key_obj.data.offset_value_list, key_obj.data.num_values + 1)
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      value_list.each do |value|
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        # TODO: use #to_s to make sure value.data.name is a String
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        res << (value.data.flag > 0 ? value.data.name : nil)
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      end
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      res
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    end
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  end
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end
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end
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end
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