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Class: Gem::Package::TarHeader

Relationships & Source Files
Inherits: Object
Defined in: lib/rubygems/package/tar_header.rb

Overview

A header for a tar file

Constant Summary

  • FIELDS =

    Fields in the tar header

    # File 'lib/rubygems/package/tar_header.rb', line 35 
    [
  :checksum,
  :devmajor,
  :devminor,
  :gid,
  :gname,
  :linkname,
  :magic,
  :mode,
  :mtime,
  :name,
  :prefix,
  :size,
  :typeflag,
  :uid,
  :uname,
  :version,
]
  • PACK_FORMAT =

    Pack format for a tar header

    # File 'lib/rubygems/package/tar_header.rb', line 57 
    'a100' + # name
'a8'   + # mode
'a8'   + # uid
'a8'   + # gid
'a12'  + # size
'a12'  + # mtime
'a7a'  + # chksum
'a'    + # typeflag
'a100' + # linkname
'a6'   + # magic
'a2'   + # version
'a32'  + # uname
'a32'  + # gname
'a8'   + # devmajor
'a8'   + # devminor
'a155'
  • UNPACK_FORMAT =

    Unpack format for a tar header

    # File 'lib/rubygems/package/tar_header.rb', line 77 
    'A100' + # name
'A8'   + # mode
'A8'   + # uid
'A8'   + # gid
'A12'  + # size
'A12'  + # mtime
'A8'   + # checksum
'A'    + # typeflag
'A100' + # linkname
'A6'   + # magic
'A2'   + # version
'A32'  + # uname
'A32'  + # gname
'A8'   + # devmajor
'A8'   + # devminor
'A155'

Class Method Summary

Instance Attribute Summary

Instance Method Summary

Constructor Details

.new(vals) ⇒ TarHeader

Creates a new TarHeader using vals

[ GitHub ] 

  


# File 'lib/rubygems/package/tar_header.rb', line 133



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


  







Class Method Details



  

    .from(stream)  
  



  

    

Creates a tar header from IO stream


  



  [ GitHub ]


  

  


# File 'lib/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     => strict_oct(fields.shift),
      :uid      => strict_oct(fields.shift),
      :gid      => strict_oct(fields.shift),
      :size     => strict_oct(fields.shift),
      :mtime    => strict_oct(fields.shift),
      :checksum => strict_oct(fields.shift),
      :typeflag => fields.shift,
      :linkname => fields.shift,
      :magic    => fields.shift,
      :version  => strict_oct(fields.shift),
      :uname    => fields.shift,
      :gname    => fields.shift,
      :devmajor => strict_oct(fields.shift),
      :devminor => strict_oct(fields.shift),
      :prefix   => fields.shift,

      :empty => empty
end


  








  

    .strict_oct(str)  
  



  

    
  





  
Raises:


    
  
  • 
    (ArgumentError)
  
    • 





  [ GitHub ]


  

  


# File 'lib/rubygems/package/tar_header.rb', line 125



def self.strict_oct(str)
  return str.oct if str =~ /\A[0-7]*\z/
  raise ArgumentError, "#{str.inspect} is not an octal string"
end


  







Instance Attribute Details



  

    #empty?  ⇒ Boolean  (readonly)
  



  

    

Is the tar entry empty?


  





  


  [ GitHub ]


  

  


# File 'lib/rubygems/package/tar_header.rb', line 160



def empty?
  @empty
end


  







Instance Method Details



  

    #calculate_checksum(header)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubygems/package/tar_header.rb', line 199



def calculate_checksum(header)
  header.unpack("C*").inject { |a, b| a + b }
end


  








  

    #header(checksum = @checksum)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubygems/package/tar_header.rb', line 203



def header(checksum = @checksum)
  header = [
    name,
    oct(mode, 7),
    oct(uid, 7),
    oct(gid, 7),
    oct(size, 11),
    oct(mtime, 11),
    checksum,
    " ",
    typeflag,
    linkname,
    magic,
    oct(version, 2),
    uname,
    gname,
    oct(devmajor, 7),
    oct(devminor, 7),
    prefix
  ]

  header = header.pack PACK_FORMAT

  header << ("\0" * ((512 - header.size) % 512))
end


  








  

    #oct(num, len)   (private)
  

  [ GitHub ]


  

  


# File 'lib/rubygems/package/tar_header.rb', line 229



def oct(num, len)
  "%0#{len}o" % num
end


  








  

    #update_checksum  
  



  

    

Updates the TarHeader's checksum


  



  [ GitHub ]


  

  


# File 'lib/rubygems/package/tar_header.rb', line 192



def update_checksum
  header = header " " * 8
  @checksum = oct calculate_checksum(header), 6
end