Gem::Package::TarHeader

A header for a tar file

Constants

FIELDS: Fields in the tar header
PACK_FORMAT: Pack format for a tar header
UNPACK_FORMAT: Unpack format for a tar header

Public Class Methods

from(stream)

Creates a tar header from IO stream

 
               # File rubygems/package/tar_header.rb, line 99
def self.from(stream)
  header = stream.read 512
  empty = (header == "\0" * 512)

  fields = header.unpack UNPACK_FORMAT

  new :name     => fields.shift,
      :mode     => fields.shift.oct,
      :uid      => fields.shift.oct,
      :gid      => fields.shift.oct,
      :size     => fields.shift.oct,
      :mtime    => fields.shift.oct,
      :checksum => fields.shift.oct,
      :typeflag => fields.shift,
      :linkname => fields.shift,
      :magic    => fields.shift,
      :version  => fields.shift.oct,
      :uname    => fields.shift,
      :gname    => fields.shift,
      :devmajor => fields.shift.oct,
      :devminor => fields.shift.oct,
      :prefix   => fields.shift,

      :empty => empty
end

new(vals)

Creates a new TarHeader using vals

 
               # File rubygems/package/tar_header.rb, line 128
def initialize(vals)
  unless vals[:name] && vals[:size] && vals[:prefix] && vals[:mode] then
    raise ArgumentError, ":name, :size, :prefix and :mode required"
  end

  vals[:uid] ||= 0
  vals[:gid] ||= 0
  vals[:mtime] ||= 0
  vals[:checksum] ||= ""
  vals[:typeflag] = "0" if vals[:typeflag].nil? || vals[:typeflag].empty?
  vals[:magic] ||= "ustar"
  vals[:version] ||= "00"
  vals[:uname] ||= "wheel"
  vals[:gname] ||= "wheel"
  vals[:devmajor] ||= 0
  vals[:devminor] ||= 0

  FIELDS.each do |name|
    instance_variable_set "@#{name}", vals[name]
  end

  @empty = vals[:empty]
end

Public Instance Methods

empty?()

Is the tar entry empty?

 
               # File rubygems/package/tar_header.rb, line 155
def empty?
  @empty
end

update_checksum()

Updates the TarHeader’s checksum

 
               # File rubygems/package/tar_header.rb, line 187
def update_checksum
  header = header " " * 8
  @checksum = oct calculate_checksum(header), 6
end