Class: Origami::Stream

Inherits:
Object
  • Object
show all
Includes:
FieldAccessor, Object, StandardObject
Defined in:
lib/origami/stream.rb,
lib/origami/obfuscation.rb

Overview

Class representing a PDF Stream Object. Streams can be used to hold any kind of data, especially binary data.

Constant Summary collapse

TOKENS =

:nodoc:

[ "stream" + WHITECHARS_NORET + "(\\r\\n|\\r|\\n)" , "endstream" ]
@@regexp_open =
Regexp.new(WHITESPACES + TOKENS.first)
@@regexp_close =
Regexp.new(TOKENS.last)
@@type_signatures =
{}
@@type_keys =
[]
@@defined_filters =

Actually only 5 first ones are implemented, other ones are mainly about image data processing (JPEG, JPEG2000 …)

%i[
  ASCIIHexDecode
  ASCII85Decode
  LZWDecode
  FlateDecode
  RunLengthDecode
   CCITTFaxDecode
  JBIG2Decode
  DCTDecode
  JPXDecode
   AHx
  A85
  LZW
  Fl
  RL
  CCF
  DCT
]

Constants included from StandardObject

Origami::StandardObject::DEFAULT_ATTRIBUTES

Instance Attribute Summary collapse

Attributes included from Object

#file_offset, #generation, #no, #objstm_offset, #parent

Class Method Summary collapse

Instance Method Summary collapse

Methods included from FieldAccessor

#method_missing, #respond_to_missing?

Methods included from StandardObject

included, #version_required

Methods included from Object

#<=>, #copy, #document, #export, included, #indirect?, #indirect_parent, #logicalize, #logicalize!, #native_type, #reference, #set_document, #set_indirect, skip_until_next_obj, #solve, #to_o, #type, typeof, #version_required, #xrefs

Constructor Details

#initialize(data = "", dictionary = {}) ⇒ Stream

Creates a new PDF Stream.

data

The Stream uncompressed data.

dictionary

A hash representing the Stream attributes.


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# File 'lib/origami/stream.rb', line 89

def initialize(data = "", dictionary = {})
    super()

    set_indirect(true)

    @encoded_data = nil
    @dictionary, @data = Dictionary.new(dictionary), data
    @dictionary.parent = self
end

Dynamic Method Handling

This class handles dynamic methods through the method_missing method in the class Origami::FieldAccessor

Instance Attribute Details

#dictionaryObject

Returns the value of attribute dictionary


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# File 'lib/origami/stream.rb', line 74

def dictionary
  @dictionary
end

Class Method Details

.add_type_signature(key, value) ⇒ Object

:nodoc:


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# File 'lib/origami/stream.rb', line 164

def self.add_type_signature(key, value) #:nodoc:
    key, value = key.to_o, value.to_o

    # Inherit the superclass type information.
    if not @@type_signatures.key?(self) and @@type_signatures.key?(self.superclass)
        @@type_signatures[self] = @@type_signatures[self.superclass].dup
    end

    @@type_signatures[self] ||= {}
    @@type_signatures[self][key] = value

    @@type_keys.push(key) unless @@type_keys.include?(key)
end

.guess_type(hash) ⇒ Object

:nodoc:


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# File 'lib/origami/stream.rb', line 178

def self.guess_type(hash) #:nodoc:
    best_type = self

    @@type_signatures.each_pair do |klass, keys|
        next unless klass < best_type

        best_type = klass if keys.all? { |k,v| hash[k] == v }
    end

    best_type
end

.parse(stream, parser = nil) ⇒ Object

:nodoc:


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# File 'lib/origami/stream.rb', line 116

def self.parse(stream, parser = nil) #:nodoc:
    dictionary = Dictionary.parse(stream, parser)
    return dictionary if not stream.skip(@@regexp_open)

    length = dictionary[:Length]
    if not length.is_a?(Integer)
        raw_data = stream.scan_until(@@regexp_close)
        if raw_data.nil?
            raise InvalidStreamObjectError,
                    "Stream shall end with a 'endstream' statement"
        end
    else
        length = length.value
        raw_data = stream.peek(length)
        stream.pos += length

        if not ( unmatched = stream.scan_until(@@regexp_close) )
            raise InvalidStreamObjectError,
                "Stream shall end with a 'endstream' statement"
        end

        raw_data << unmatched
    end

    stm =
        if Origami::OPTIONS[:enable_type_guessing]
            self.guess_type(dictionary).new('', dictionary)
        else
            Stream.new('', dictionary)
        end

    raw_data.chomp!(TOKENS.last)

    if raw_data[-1,1] == "\n"
        if raw_data[-2,1] == "\r"
            raw_data = raw_data[0, raw_data.size - 2]
        else
            raw_data = raw_data[0, raw_data.size - 1]
        end
    end
    #raw_data.chomp! if length.is_a?(Integer) and length < raw_data.length

    stm.encoded_data = raw_data
    stm.file_offset = dictionary.file_offset

    stm
end

Instance Method Details

#[](key) ⇒ Object

:nodoc:


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# File 'lib/origami/stream.rb', line 396

def [](key) #:nodoc:
    @dictionary[key]
end

#[]=(key, val) ⇒ Object

:nodoc:


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# File 'lib/origami/stream.rb', line 400

def []=(key,val) #:nodoc:
    @dictionary[key] = val
end

#cast_to(type, _parser = nil) ⇒ Object


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# File 'lib/origami/stream.rb', line 246

def cast_to(type, _parser = nil)
    super(type)

    cast = type.new("", self.dictionary.copy)
    cast.encoded_data = self.encoded_data.dup
    cast.no, cast.generation = self.no, self.generation
    cast.set_indirect(true)
    cast.set_document(self.document)
    cast.file_offset = self.file_offset

    cast
end

#dataObject Also known as: decoded_data

Returns the uncompressed stream content.


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# File 'lib/origami/stream.rb', line 266

def data
    self.decode! unless decoded?

    @data
end

#data=(str) ⇒ Object Also known as: decoded_data=

Sets the uncompressed stream content.

str

The new uncompressed data.


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# File 'lib/origami/stream.rb', line 277

def data=(str)
    @encoded_data = nil
    @data = str
end

#decode!Object

Uncompress the stream data.


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# File 'lib/origami/stream.rb', line 304

def decode!
    self.decrypt! if self.is_a?(Encryption::EncryptedStream)
    return if decoded?

    filters = self.filters

    if filters.empty?
        @data = @encoded_data.dup
        return
    end

    unless filters.all?{|filter| filter.is_a?(Name)}
        raise InvalidStreamObjectError, "Invalid Filter type parameter"
    end

    dparams = decode_params

    @data = @encoded_data.dup
    @data.freeze

    filters.each_with_index do |filter, layer|
        params = dparams[layer].is_a?(Dictionary) ? dparams[layer] : {}

        # Handle Crypt filters.
        if filter == :Crypt
            raise Filter::Error, "Crypt filter must be the first filter" unless layer.zero?

            # Skip the Crypt filter.
            next
        end

        begin
            @data = decode_data(@data, filter, params)
        rescue Filter::Error => error
            @data = error.decoded_data if error.decoded_data
            raise
        end
    end

    self
end

#each_filterObject

Iterates over each Filter in the Stream.


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# File 'lib/origami/stream.rb', line 193

def each_filter
    filters = self.Filter

    return enum_for(__method__) do
        case filters
        when NilClass then 0
        when Array then filters.length
        else
            1
        end
    end unless block_given?

    return if filters.nil?

    if filters.is_a?(Array)
        filters.each do |filter| yield(filter) end
    else
        yield(filters)
    end

    self
end

#each_key(&b) ⇒ Object

:nodoc:


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# File 'lib/origami/stream.rb', line 404

def each_key(&b) #:nodoc:
    @dictionary.each_key(&b)
end

#encode!Object

Compress the stream data.


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# File 'lib/origami/stream.rb', line 349

def encode!
    return if encoded?
    filters = self.filters

    if filters.empty?
        @encoded_data = @data.dup
        return
    end

    unless filters.all?{|filter| filter.is_a?(Name)}
        raise InvalidStreamObjectError, "Invalid Filter type parameter"
    end

    dparams = decode_params

    @encoded_data = @data.dup
    (filters.length - 1).downto(0) do |layer|
        params = dparams[layer].is_a?(Dictionary) ? dparams[layer] : {}
        filter = filters[layer]

        # Handle Crypt filters.
        if filter == :Crypt
            raise Filter::Error, "Crypt filter must be the first filter" unless layer.zero?

            # Skip the Crypt filter.
            next
        end

        @encoded_data = encode_data(@encoded_data, filter, params)
    end

    self.Length = @encoded_data.length

    self
end

#encoded_dataObject

Returns the raw compressed stream content.


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# File 'lib/origami/stream.rb', line 286

def encoded_data
    self.encode! unless encoded?

    @encoded_data
end

#encoded_data=(str) ⇒ Object

Sets the raw compressed stream content.

str

the new raw data.


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# File 'lib/origami/stream.rb', line 296

def encoded_data=(str)
    @encoded_data = str
    @data = nil
end

#filtersObject

Returns an Array of Filters for this Stream.


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# File 'lib/origami/stream.rb', line 219

def filters
    self.each_filter.to_a
end

#key?(name) ⇒ Boolean Also known as: has_key?

Returns:


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# File 'lib/origami/stream.rb', line 408

def key?(name)
    @dictionary.key?(name)
end

#post_buildObject


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# File 'lib/origami/stream.rb', line 110

def post_build
    self.Length = @encoded_data.length

    super
end

#pre_buildObject


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# File 'lib/origami/stream.rb', line 104

def pre_build
    encode!

    super
end

#set_predictor(predictor, colors: 1, bitspercomponent: 8, columns: 1) ⇒ Object

Set predictor type for the current Stream. Applies only for LZW and FlateDecode filters.


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# File 'lib/origami/stream.rb', line 227

def set_predictor(predictor, colors: 1, bitspercomponent: 8, columns: 1)
    filters = self.filters

    layer = filters.index(:FlateDecode) or filters.index(:LZWDecode)
    if layer.nil?
        raise InvalidStreamObjectError, 'Predictor functions can only be used with Flate or LZW filters'
    end

    params = Filter::LZW::DecodeParms.new
    params[:Predictor] = predictor
    params[:Colors] = colors if colors != 1
    params[:BitsPerComponent] = bitspercomponent if bitspercomponent != 8
    params[:Columns] = columns if columns != 1

    set_decode_params(layer, params)

    self
end

#to_obfuscated_strObject


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# File 'lib/origami/obfuscation.rb', line 220

def to_obfuscated_str
    content = ""

    content << @dictionary.to_obfuscated_str
    content << "stream" + EOL
    content << self.encoded_data
    content << EOL << TOKENS.last

    super(content)
end

#to_s(indent: 1, tab: "\t") ⇒ Object

:nodoc:


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# File 'lib/origami/stream.rb', line 385

def to_s(indent: 1, tab: "\t") #:nodoc:
    content = ""

    content << @dictionary.to_s(indent: indent, tab: tab)
    content << "stream" + EOL
    content << self.encoded_data
    content << EOL << TOKENS.last

    super(content)
end

#valueObject

:nodoc:


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# File 'lib/origami/stream.rb', line 259

def value #:nodoc:
    self
end