Class: GitDB::Pack

Inherits:
Object
  • Object
show all
Defined in:
lib/git-db/pack.rb

Defined Under Namespace

Classes: PackObject

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(io) ⇒ Pack

Returns a new instance of Pack.



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# File 'lib/git-db/pack.rb', line 11

def initialize(io)
  @io = GitDB::Utility::CountingIO.new(io)
end

Instance Attribute Details

#io ⇒ Object (readonly)

Returns the value of attribute io.



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# File 'lib/git-db/pack.rb', line 9

def io
  @io
end

Instance Method Details

#read ⇒ Object 



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# File 'lib/git-db/pack.rb', line 15

def read
  header = io.read(12)
  return nil unless header

  signature, version, entries = header.unpack("a4NN")
  raise 'invalid pack signature' unless signature == 'PACK'
  raise 'invalid version'        unless version   == 2

  objects = {}

  1.upto(entries) do
    object_offset = io.offset

    type, size = unpack_pack_header(io)

    object = case type
      when 1 then
        GitDB::Objects::Commit.new(read_compressed(io))
      when 2 then
        GitDB::Objects::Tree.new(read_compressed(io))
      when 3 then
        GitDB::Objects::Blob.new(read_compressed(io))
      when 4 then
        GitDB::Objects::Tag.new(read_compressed(io))
      when 5 then
        raise 'Invalid Type: 5'
      when 6 then
        offset = object_offset - unpack_delta_size(io)
        patch  = read_compressed(io)
        base   = objects[offset]
        base.class.new(apply_patch(base.data, patch))
      when 7 then
        # TODO
        sha = io.read(20)
        # base = lookup_by_sha(sha)
        patch = read_compressed(io)
        # base.class.new(apply_patch(base.data, patch))
        nil
    end

    objects[object_offset] = object
  end

  GitDB.log(objects.values.map { |o| o.inspect })

  io.read(20)

  objects.values.compact
end

#write(entries) ⇒ Object 



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# File 'lib/git-db/pack.rb', line 65

def write(entries)
  buffer = ""
  signature = ["PACK", 2, entries.length].pack("a4NN")
  #GitDB.log("SIGNATURE: #{signature}")
  io.write(signature)
  buffer << signature
  
  entries.each do |entry|
    header = pack_pack_header(entry.type, entry.data.length)
    #GitDB.log("HEADER: #{header.inspect}")
    io.write(header)
    buffer << header
    compressed = Zlib::Deflate.deflate(entry.data)
    io.write(compressed)
    buffer << compressed
  end
  
  #GitDB.log("BUFFER: #{buffer.inspect}")
  signature = GitDB::hex_to_sha1(Digest::SHA1.hexdigest(buffer))
  #GitDB.log("SIGNATURE: #{signature.inspect}")
  io.write(signature)
  io.flush
end