Class: VirtDisk::PartitionType::DosPartition

Inherits:
VirtDisk::Partition show all
Includes:
LogDecorator::Logging, ExportMethods
Defined in:
lib/virt_disk/partition_type/dos_partition.rb

Constant Summary collapse

DOS_NPTE = 
4
PTYPE_EXT_CHS = 
0x05
PTYPE_EXT_LBA = 
0x0f
PTYPE_LDM = 
0x42

Constants inherited from VirtDisk::Partition

VirtDisk::Partition::DOS_PARTITION_ENTRY, VirtDisk::Partition::DOS_PT_START, VirtDisk::Partition::DOS_SIG, VirtDisk::Partition::GPT_SIG, VirtDisk::Partition::MBR_SIZE, VirtDisk::Partition::PTE_LEN

Instance Attribute Summary

Attributes inherited from VirtDisk::Partition

#end_lba, #pnum, #ptype, #start_lba

Attributes inherited from ClientHead

#end_byte_addr, #seek_pos, #size, #start_byte_addr

Class Method Summary collapse

Instance Method Summary collapse

Methods included from ExportMethods

#delegate, #delegate=, #exported?, included, #method_missing, #respond_to_missing?

Methods inherited from ClientHead

#close, #mod_read, #mod_write, #read, #seek, #write

Constructor Details

#initialize(disk, ptype, pnum, start_lba, size_in_blocks) ⇒ DosPartition

Returns a new instance of DosPartition.



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# File 'lib/virt_disk/partition_type/dos_partition.rb', line 12

def initialize(disk, ptype, pnum, start_lba, size_in_blocks)
  # Convert partition size to partition end LBA.
  super(disk, ptype, pnum, start_lba, start_lba + size_in_blocks)
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method in the class VirtDisk::ExportMethods

Class Method Details

.discover_dos_ext_partitions(disk, pri_base_lba, ptBaseLBA, pnum) ⇒ Object

Discover secondary file system partitions within a primary extended partition.

pri_base_lba is the LBA of the primary extended partition.

All pointers to secondary extended partitions are relative to this base.

ptBaseLBA is the LBA of the partition table within the current extended partition.

All pointers to secondary file system partitions are relative to this base.



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# File 'lib/virt_disk/partition_type/dos_partition.rb', line 76

def self.discover_dos_ext_partitions(disk, pri_base_lba, ptBaseLBA, pnum) # rubocop:disable AbcSize
  ra = []
  seek(ptBaseLBA * @blockSize, IO::SEEK_SET)
  mbr = read(MBR_SIZE)

  #
  # Create and add disk object for secondary file system partition.
  # NOTE: the start of the partition is relative to ptBaseLBA.
  #
  pte = DOS_PT_START
  pt_entry = DOS_PARTITION_ENTRY.decode(mbr[pte, PTE_LEN])
  ra << new(
    disk,
    pt_entry[:ptype],
    pnum,
    pt_entry[:start_lba] + ptBaseLBA,
    pt_entry[:part_size]
  ) if pt_entry[:ptype] != 0

  #
  # Follow the chain to the next secondary extended partition.
  # NOTE: the start of the partition is relative to pri_base_lba.
  #
  pte += PTE_LEN
  pt_entry = DOS_PARTITION_ENTRY.decode(mbr[pte, PTE_LEN])
  ra.concat(
    discover_dos_ext_partitions(
      disk,
      pri_base_lba,
      pt_entry[:start_lba] + pri_base_lba,
      pnum + 1
    )
  ) if pt_entry[:start_lba] != 0
  ra
end

.discover_dos_pri_partitions(disk, mbr) ⇒ Object

rubocop:disable AbcSize



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# File 'lib/virt_disk/partition_type/dos_partition.rb', line 35

def self.discover_dos_pri_partitions(disk, mbr) # rubocop:disable AbcSize
  pte = DOS_PT_START
  partitions = []
  (1..DOS_NPTE).each do |n|
    pt_entry = DOS_PARTITION_ENTRY.decode(mbr[pte, PTE_LEN])
    pte += PTE_LEN
    ptype = pt_entry[:ptype]

    #
    # If this os an LDM (dynamic) disk, then ignore any partitions.
    #
    if ptype == PTYPE_LDM
      _log.debug "<#{disk.object_id}> detected LDM (dynamic) disk"
      return([])
    end

    if ptype == PTYPE_EXT_CHS || ptype == PTYPE_EXT_LBA
      partitions.concat(
        discover_dos_ext_partitions(
          disk,
          pt_entry[:start_lba],
          pt_entry[:start_lba],
          DOS_NPTE + 1
        )
      )
      next
    end
    partitions.push(new(disk, ptype, n, pt_entry[:start_lba], pt_entry[:part_size])) if ptype != 0
  end
  partitions
end

.discover_partitions(disk) ⇒ Object

rubocop:disable AbcSize



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# File 'lib/virt_disk/partition_type/dos_partition.rb', line 17

def self.discover_partitions(disk) # rubocop:disable AbcSize
  _log.debug "<#{disk.object_id}> disk file: #{disk.file_name}" if disk.respond_to? :file_name
  mbr = disk.mod_read(0, MBR_SIZE)

  if mbr.length < MBR_SIZE
    _log.info "<#{disk.object_id}> disk does not contain a master boot record"
    return []
  end

  sig = mbr[510..511].unpack('H4')

  pt_entry = DOS_PARTITION_ENTRY.decode(mbr[DOS_PT_START, PTE_LEN])
  ptype = pt_entry[:ptype]

  return [] if sig[0] != DOS_SIG || ptype == GPT_SIG
  discover_dos_pri_partitions(disk, mbr)
end