Class: Gem::Package::TarHeader

Inherits:
Object
  • Object
show all
Defined in:
lib/rubygems/package/tar_header.rb

Overview

-- struct tarfile_entry_posix

char name[100];     # ASCII + (Z unless filled)
char mode[8];       # 0 padded, octal, null
char uid[8];        # ditto
char gid[8];        # ditto
char size[12];      # 0 padded, octal, null
char mtime[12];     # 0 padded, octal, null
char checksum[8];   # 0 padded, octal, null, space
char typeflag[1];   # file: "0"  dir: "5"
char linkname[100]; # ASCII + (Z unless filled)
char magic[6];      # "ustar\0"
char version[2];    # "00"
char uname[32];     # ASCIIZ
char gname[32];     # ASCIIZ
char devmajor[8];   # 0 padded, octal, null
char devminor[8];   # o padded, octal, null
char prefix[155];   # ASCII + (Z unless filled)

; ++ A header for a tar file

Constant Summary

FIELDS =

Fields in the tar header

[
  :checksum,
  :devmajor,
  :devminor,
  :gid,
  :gname,
  :linkname,
  :magic,
  :mode,
  :mtime,
  :name,
  :prefix,
  :size,
  :typeflag,
  :uid,
  :uname,
  :version,
]
PACK_FORMAT =

Pack format for a tar header

'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

'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 (collapse)

Instance Method Summary (collapse)

Constructor Details

- (TarHeader) initialize(vals)

Creates a new TarHeader using vals



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# File 'lib/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"
  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

+ (Object) from(stream)

Creates a tar header from IO stream



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# 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     => 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

Instance Method Details

- (Object) ==(other)

:nodoc:



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# File 'lib/rubygems/package/tar_header.rb', line 159

def ==(other) # :nodoc:
  self.class === other and
  @checksum == other.checksum and
  @devmajor == other.devmajor and
  @devminor == other.devminor and
  @gid      == other.gid      and
  @gname    == other.gname    and
  @linkname == other.linkname and
  @magic    == other.magic    and
  @mode     == other.mode     and
  @mtime    == other.mtime    and
  @name     == other.name     and
  @prefix   == other.prefix   and
  @size     == other.size     and
  @typeflag == other.typeflag and
  @uid      == other.uid      and
  @uname    == other.uname    and
  @version  == other.version
end

- (Object) calculate_checksum(header) (private)



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# File 'lib/rubygems/package/tar_header.rb', line 194

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

- (Boolean) empty?

Is the tar entry empty?

Returns:

  • (Boolean)


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# File 'lib/rubygems/package/tar_header.rb', line 155

def empty?
  @empty
end

- (Object) header(checksum = @checksum) (private)



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# File 'lib/rubygems/package/tar_header.rb', line 198

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

- (Object) oct(num, len) (private)



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# File 'lib/rubygems/package/tar_header.rb', line 224

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

- (Object) to_s

:nodoc:



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# File 'lib/rubygems/package/tar_header.rb', line 179

def to_s # :nodoc:
  update_checksum
  header
end

- (Object) update_checksum

Updates the TarHeader's checksum



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# File 'lib/rubygems/package/tar_header.rb', line 187

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

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