Class: XFS::BmapBTreeRootNode

Inherits:
Object
  • Object
show all
Defined in:
lib/fs/xfs/bmap_btree_root_node.rb

Overview

Handle the BTree Root Node in the Disk Inode

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(data, inode) ⇒ BmapBTreeRootNode

Returns a new instance of BmapBTreeRootNode.



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# File 'lib/fs/xfs/bmap_btree_root_node.rb', line 37

def initialize(data, inode)
  raise "XFS::BmapBTreeRootNode: Nil buffer" if data.nil?
  @inode         = inode
  @header        = BMAP_BTREE_ROOT_NODE_HEADER.decode(data[0..inode.length])
  @level         = @header['level']
  @entry_count   = @header['entry_count']
  raise "XFS::BmapBTreeRootNode: Invalid Root Node Level" if @level.nil? || @level == 0
  header_size    = SIZEOF_BMAP_BTREE_ROOT_NODE_HEADER
  return if @entry_count == 0
  #
  # The Root Node contains an array of starting offsets followed by
  # an array of block numbers.  While only the required number of entries
  # are initialized, there is space left for the maximum number of entries
  # that may fit in the disk inode data fork (eliminating any space taken
  # up by extended attributes).
  # We only care about the block numbers.  The offsets of individual data blocks are
  # also kept in the BmapBTreeRecord
  #
  fork_size       = @inode.dfork_size(Inode::XFS_DATA_FORK)
  maximum_records = (fork_size - header_size) / SIZEOF_BMAP_BTREE_ROOT_NODE_ENTRIES
  return if maximum_records == 0
  @blocks         = []
  offset_size     = SIZEOF_BMAP_BTREE_ROOT_NODE_OFFSET
  block_size      = SIZEOF_BMAP_BTREE_ROOT_NODE_BLOCK
  size            = SIZEOF_BMAP_BTREE_ROOT_NODE_HEADER
  1.upto(@entry_count) do |i|
    start             = size + maximum_records * offset_size + (i - 1) * block_size
    block             = (data[start..start + block_size]).unpack('Q>').shift
    agbno             = inode.sb.fsb_to_agbno(block)
    agno              = inode.sb.fsb_to_agno(block)
    real_block        = inode.sb.agbno_to_real_block(agno, agbno)
    @blocks.concat([real_block])
  end
end

Instance Attribute Details

#blocks ⇒ Object

Returns the value of attribute blocks.



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# File 'lib/fs/xfs/bmap_btree_root_node.rb', line 35

def blocks
  @blocks
end

#entry_count ⇒ Object

Returns the value of attribute entry_count.



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# File 'lib/fs/xfs/bmap_btree_root_node.rb', line 35

def entry_count
  @entry_count
end

#level ⇒ Object

Returns the value of attribute level.



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# File 'lib/fs/xfs/bmap_btree_root_node.rb', line 35

def level
  @level
end