Class: ZSteg::FileCmd

Inherits:
Object
  • Object
show all
Defined in:
lib/zsteg/file_cmd.rb

Defined Under Namespace

Classes: Result

Constant Summary collapse

IGNORES = 
[
  'data',
  'empty',
  'Sendmail frozen configuration',
  'DBase 3 data file',
  'DOS executable',
  'Dyalog APL',
  '8086 relocatable',
  'SysEx File',
  'COM executable',
  'Non-ISO extended-ASCII text',
  'ISO-8859 text',
  'very short file',
  'International EBCDIC text',
  'lif file',
  'AmigaOS bitmap font',
  'a python script text executable' # common false positive
]
MIN_DATA_SIZE = 
5

Instance Method Summary collapse

Instance Method Details

#check_data(data) ⇒ Object 



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# File 'lib/zsteg/file_cmd.rb', line 76

def check_data data
  @tempfile ||= Tempfile.new('zsteg', :encoding => 'binary')
  @tempfile.rewind
  @tempfile.write data
  @tempfile.flush
  check_file @tempfile.path
end

#check_file(fname) ⇒ Object 



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# File 'lib/zsteg/file_cmd.rb', line 70

def check_file fname
  @stdin.puts fname
  r = @stdout.gets.force_encoding('binary').strip
  IGNORES.any?{ |x| r.index(x) == 0 } ? nil : r
end

#data2result(data) ⇒ Object

checks data and resurns Result, if any



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# File 'lib/zsteg/file_cmd.rb', line 85

def data2result data
  return if data.size < MIN_DATA_SIZE

  title = check_data data
  return unless title

  if title[/UTF-8 Unicode text/i]
    begin
      t = data.force_encoding("UTF-8")
    rescue
      t = data.force_encoding('binary')
    end
    if t.size >= Checker::DEFAULT_MIN_STR_LEN
      ZSteg::Result::UnicodeText.new(t,0)
    end
  else
    Result.new(title,data)
  end
end

#start! ⇒ Object 



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# File 'lib/zsteg/file_cmd.rb', line 66

def start!
  @stdin, @stdout, @stderr, @wait_thr = Open3.popen3("file -n -b -f -")
end

#stop! ⇒ Object 



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# File 'lib/zsteg/file_cmd.rb', line 105

def stop!
  @stdin.close
  @stdout.close
  @stderr.close
ensure
  if @tempfile
    @tempfile.close
    @tempfile.unlink
    @tempfile = nil
  end
end