Class: CPIO::ArchiveHeader

Inherits:
Object
  • Object
show all
Defined in:
lib/excavate/extractors/cpio/cpio_old_format.rb

Constant Summary collapse

Magic = 
'070707'
Fields = 
[[6,  :magic   ],
[6,  :dev     ],
[6,  :inode   ],
[6,  :mode    ],
[6,  :uid     ],
[6,  :gid     ],
[6,  :numlinks],
[6,  :rdev    ],
[11, :mtime   ],
[6,  :namesize],
[11, :filesize]]
FieldDefaults = 
{:magic    => Integer(Magic),
:dev      => 0777777,
:inode    => 0,
:mode     => 0100444,
:uid      => 0,
:gid      => 0,
:numlinks => 1,
:rdev     => 0,
:mtime    => lambda { Time.now.to_i }}
FieldMaxValues = 
Fields.inject({}) do |map,(width,name)|
  map[name] = Integer("0#{'7' * width}")
  map
end
HeaderSize = 
Fields.inject(0) do |sum,(size,name)|
  sum + size
end
HeaderUnpackFormat = 
Fields.collect do |size,name|
  "a%s" % size
end.join('')

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(attrs) ⇒ ArchiveHeader

Returns a new instance of ArchiveHeader.



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# File 'lib/excavate/extractors/cpio/cpio_old_format.rb', line 54

def initialize(attrs)
  @attrs = attrs
  check_attrs
end

Class Method Details

.from(io) ⇒ Object 



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# File 'lib/excavate/extractors/cpio/cpio_old_format.rb', line 59

def self.from(io)
  data = io.read(HeaderSize)
  verify_size(data)
  verify_magic(data)
  new(unpack_data(data))
end

.unpack_data(data) ⇒ Object 



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# File 'lib/excavate/extractors/cpio/cpio_old_format.rb', line 101

def self.unpack_data(data)
  contents = {}
  data.unpack(HeaderUnpackFormat).zip(Fields) do |(chunk,(size,name))|
    contents[name] = Integer("0#{chunk}")
  end
  contents
end

.verify_magic(data) ⇒ Object 



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# File 'lib/excavate/extractors/cpio/cpio_old_format.rb', line 95

def self.verify_magic(data)
  unless data[0..Magic.size - 1] == Magic
    raise ArchiveFormatError, "Archive does not seem to be a valid CPIO archive with ASCII headers."
  end
end

.verify_size(data) ⇒ Object 



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# File 'lib/excavate/extractors/cpio/cpio_old_format.rb', line 89

def self.verify_size(data)
  unless data.size == HeaderSize
    raise ArchiveFormatError, "Header is not long enough to be a valid CPIO archive with ASCII headers."
  end
end

.with_defaults(opts) ⇒ Object 



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# File 'lib/excavate/extractors/cpio/cpio_old_format.rb', line 66

def self.with_defaults(opts)
  name = opts[:name]
  defaults = FieldDefaults.merge(:mode => opts[:mode], :filesize => opts[:filesize], :namesize => name.size + 1)
  new(defaults)
end

Instance Method Details

#to_data ⇒ Object 



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# File 'lib/excavate/extractors/cpio/cpio_old_format.rb', line 72

def to_data
  Fields.collect do |(width,name)|
    raise ArchiveFormatError, "Expected header to have key #{name}" unless @attrs.has_key?(name)
    val = @attrs[name].respond_to?(:to_proc) ? @attrs[name].call : @attrs[name]
    raise ArchiveFormatError, "Header value for #{name} exceeds max length of #{FieldMaxValues[name]}" if val > FieldMaxValues[name]
    sprintf("%0*o", Fields.rassoc(name).first, val)
  end.join('')
end