Module: VMWareCowdDisk

Defined in:
lib/disk/modules/VMWareCowdDisk.rb

Constant Summary collapse

COWD_EXTENT_HEADER = 
BinaryStruct.new([
  'L', 'magicNumber',
  'L', 'version',
  'L', 'flags',
  'L', 'numSectors',
  'L', 'grainSize',
  'L', 'gdOffset',
  'L', 'numGDEntries',
  'L', 'freeSector',
])
SIZEOF_COWD_EXTENT_HEADER = 
COWD_EXTENT_HEADER.size
GTE_SIZE = 
4
GDE_SIZE = 
4
GDE_COVERAGE = 
2097152
ENTRIES_PER_TABLE = 
4096
GT_SECTORS = 
32

Instance Method Summary collapse

Instance Method Details

#d_close ⇒ Object 



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# File 'lib/disk/modules/VMWareCowdDisk.rb', line 116

def d_close
  @vmwareCowDisk_file.close
end

#d_init ⇒ Object 



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# File 'lib/disk/modules/VMWareCowdDisk.rb', line 25

def d_init
  self.diskType = "VMWare CopyOnWrite"
  self.blockSize = 512
  fileMode = MiqDiskCommon.file_mode(dInfo)
  @dParent = @dInfo.parent

  @vmwareCowDisk_file = MiqLargeFile.open(dInfo.fileName, fileMode)
  buf = @vmwareCowDisk_file.read(SIZEOF_COWD_EXTENT_HEADER)
  @EsxSparseHeader = OpenStruct.new(COWD_EXTENT_HEADER.decode(buf))

  @grainSize = @EsxSparseHeader.grainSize
  @grainBytes = @grainSize * blockSize
  @capacity = @EsxSparseHeader.numSectors * blockSize
  @gdStart = @EsxSparseHeader.gdOffset * blockSize
  @gdSize = @EsxSparseHeader.numGDEntries * GDE_SIZE
end

#d_read(pos, len, _offset = 0) ⇒ Object 



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# File 'lib/disk/modules/VMWareCowdDisk.rb', line 46

def d_read(pos, len, _offset = 0)
  gnStart, goStart = grainPos(pos)
  gnEnd, goEnd = grainPos(pos + len)

  if gnStart == gnEnd
    grainPos = getGTE(gnStart)
    if grainPos == 0
      return @dParent ? @dParent.d_read(pos, len) : MemoryBuffer.create(len)
    else
      @vmwareCowDisk_file.seek(grainPos + goStart, IO::SEEK_SET)
      return @vmwareCowDisk_file.read(len)
    end
  end

  bytesRead = 0
  rv = ''
  gnStart.upto(gnEnd) do |gn|
    so = 0
    l = @grainBytes

    if gn == gnStart
      so = goStart
      l -= so
    end
    l -= (@grainBytes - goEnd) if gn == gnEnd

    gp = getGTE(gn)
    # Mods for parent link.
    if gp == 0
      rv << (@dParent ? @dParent.d_read(pos + bytesRead, l) : MemoryBuffer.create(l))
    else
      @vmwareCowDisk_file.seek(gp + so, IO::SEEK_SET)
      rv << @vmwareCowDisk_file.read(l)
    end
    bytesRead += l
  end
  rv
end

#d_size ⇒ Object

Disk size in sectors.



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# File 'lib/disk/modules/VMWareCowdDisk.rb', line 121

def d_size
  @capacity / @blockSize
end

#d_write(pos, buf, len, _offset = 0) ⇒ Object 



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# File 'lib/disk/modules/VMWareCowdDisk.rb', line 85

def d_write(pos, buf, len, _offset = 0)
  gnStart, goStart = grainPos(pos)
  gnEnd, goEnd = grainPos(pos + len)

  if gnStart == gnEnd
    grainPos = getGTE(gnStart)
    grainPos = allocGrain(gnStart) if grainPos == 0
    @vmwareCowDisk_file.seek(grainPos + goStart, IO::SEEK_SET)
    return @vmwareCowDisk_file.write(buf, len)
  end

  bytesWritten = 0
  gnStart.upto(gnEnd) do |gn|
    so = 0
    l = @grainBytes

    if gn == gnStart
      so = goStart
      l -= so
    end
    l -= (@grainBytes - goEnd) if gn == gnEnd

    gp = getGTE(gn)
    gp = allocGrain(gn) if gp == 0
    raise "Disk is full" if gp == -1
    @vmwareCowDisk_file.seek(gp + so, IO::SEEK_SET)
    bytesWritten += @vmwareCowDisk_file.write(buf[bytesWritten, l], l)
  end
  bytesWritten
end

#getBase ⇒ Object 



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# File 'lib/disk/modules/VMWareCowdDisk.rb', line 42

def getBase
  self
end