Class: Tb::Cmd::TarReader

Inherits:
Object
  • Object
show all
Defined in:
lib/tb/cmd_tar.rb

Instance Attribute Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize(input) ⇒ TarReader

Returns a new instance of TarReader.



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# File 'lib/tb/cmd_tar.rb', line 146

def initialize(input)
  @input = input
  @offset = 0
end

Instance Attribute Details

#offset ⇒ Object (readonly)

Returns the value of attribute offset.



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# File 'lib/tb/cmd_tar.rb', line 150

def offset
  @offset
end

Instance Method Details

#calculate_hash(blocklength, filesize, alg_list) ⇒ Object

:yield: alg, result



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# File 'lib/tb/cmd_tar.rb', line 210

def calculate_hash(blocklength, filesize, alg_list) # :yield: alg, result
  digests = {}
  alg_list.each {|alg|
    c = Digest.const_get(Tb::Cmd::TAR_HASH_ALGORITHMS.fetch(alg))
    digests[alg] = c.new
  }
  rest = blocklength
  while 0 < rest
    if rest < 4096
      s = rest
    else
      s = 4096
    end
    ret = @input.read(s)
    if !ret || ret.length != s
      warn "premature end of tar archive content (#{kind})"
      raise Tb::Cmd::TarFormatError
    end
    if filesize < s
      ret = ret[0, filesize]
    end
    digests.each {|alg, d|
      d.update ret
    }
    filesize -= s
    rest -= s
  end
  @offset += blocklength
  result = {}
  digests.each {|alg, d|
    result[alg] = d.hexdigest
  }
  result
end

#get_single_record(kind) ⇒ Object 



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# File 'lib/tb/cmd_tar.rb', line 152

def get_single_record(kind)
  record = @input.read(Tb::Cmd::TAR_RECORD_LENGTH)
  if !record
    return nil
  end
  if record.length != Tb::Cmd::TAR_RECORD_LENGTH
    warn "premature end of tar archive (#{kind})"
    raise Tb::Cmd::TarFormatError
  end
  @offset += Tb::Cmd::TAR_RECORD_LENGTH
  record
end

#read_exactly(size, kind) ⇒ Object 



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# File 'lib/tb/cmd_tar.rb', line 174

def read_exactly(size, kind)
  record = @input.read(size)
  if !record
    warn "premature end of tar archive (#{kind})"
    raise Tb::Cmd::TarFormatError
  end
  if record.length != size
    warn "premature end of tar archive (#{kind})"
    raise Tb::Cmd::TarFormatError
  end
  @offset += size
  record
end

#read_single_record(kind) ⇒ Object 



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# File 'lib/tb/cmd_tar.rb', line 165

def read_single_record(kind)
  record = get_single_record(kind)
  if !record
    warn "premature end of tar archive (#{kind})"
    raise Tb::Cmd::TarFormatError
  end
  record
end

#skip(size, kind) ⇒ Object 



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# File 'lib/tb/cmd_tar.rb', line 188

def skip(size, kind)
  begin
    @input.seek(size, IO::SEEK_CUR)
  rescue Errno::ESPIPE
    rest = size
    while 0 < rest
      if rest < 4096
        s = rest
      else
        s = 4096
      end
      ret = @input.read(s)
      if !ret || ret.length != s
        warn "premature end of tar archive content (#{kind})"
        raise Tb::Cmd::TarFormatError
      end
      rest -= s
    end
  end
  @offset += size
end