Class: Ssdeep::FuzzyHash

Inherits:
FFI::MemoryPointer
  • Object
show all
Defined in:
lib/ssdeep/fuzzy_hash.rb

Class Method Summary collapse

Instance Method Summary collapse

Constructor Details

#initialize ⇒ FuzzyHash

Returns a new instance of FuzzyHash.



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# File 'lib/ssdeep/fuzzy_hash.rb', line 9

def initialize()
  super(FUZZY_MAX_RESULT)
end

Class Method Details

._load(raw) ⇒ Object

implements a _load method for Marshal



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# File 'lib/ssdeep/fuzzy_hash.rb', line 44

def self._load(raw)
  from_hash(raw)
end

.from_file(filename) ⇒ Object

Creates a new fuzzy hash from the contents of ‘filename’



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# File 'lib/ssdeep/fuzzy_hash.rb', line 76

def self.from_file(filename)
  fh = new()
  ret = Ssdeep.fuzzy_hash_filename(filename, fh)
  if ret == 0
    return fh
  else
    fh.free
    raise(StandardError, "An error occurred hashing file: #{filename.inspect}")
  end
end

.from_hash(raw) ⇒ Object

Restores a fuzzy hash that has already been generated and supplied as a string as a instance of a FuzzyHash object.



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# File 'lib/ssdeep/fuzzy_hash.rb', line 50

def self.from_hash(raw)
  fh = new()
  fh.write_string( 
    if raw.size < FUZZY_MAX_RESULT 
      raw + "\x00" 
    else 
      raw[0,FUZZY_MAX_RESULT]
    end )
  return fh
end

.from_string(buf) ⇒ Object

Creates a new fuzzy hash from a string buffer.



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# File 'lib/ssdeep/fuzzy_hash.rb', line 62

def self.from_string(buf)
  fh = new()
  p = FFI::MemoryPointer.new(buf.size)
  p.write_string(buf)
  ret = Ssdeep.fuzzy_hash_buf(p, buf.size, fh)
  if ret == 0
    return fh
  else
    fh.free
    raise(StandardError, "An error occurred hashing a string")
  end
end

Instance Method Details

#_dump(depth) ⇒ Object

implements a _dump method for Marshal



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# File 'lib/ssdeep/fuzzy_hash.rb', line 19

def _dump(depth)
  self.to_s
end

#compare(other) ⇒ Integer, ...

Returns:

  • (Integer) —

    Returns a value from zero to 100 indicating the match score of the two signatures. A match score of zero indicates the sigantures did not match.

  • (When an error occurs, such as if one of the inputs is NULL.) —

    When an error occurs, such as if one of the inputs is NULL.



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# File 'lib/ssdeep/fuzzy_hash.rb', line 30

def compare(other)
  unless other.is_a?(FuzzyHash)
    raise(TypeError, "a FuzzyHash can only be compared to another FuzzyHash")
  end
  if self.to_s == other.to_s
    return 100
  elsif (ret=Ssdeep.fuzzy_compare(self, other)) > -1
    return ret
  else
    raise(StandardError, "unknown fuzzy hash comparison error")
  end
end

#to_s ⇒ Object

returns the computed fuzzy hash as a string



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# File 'lib/ssdeep/fuzzy_hash.rb', line 14

def to_s
  self.read_string()
end