241 lines
8.3 KiB
Ruby
241 lines
8.3 KiB
Ruby
# coding: utf-8
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# typed: true
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# frozen_string_literal: true
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################################################################################
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#
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# Copyright (C) 2006 Peter J Jones (pjones@pmade.com)
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#
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# Permission is hereby granted, free of charge, to any person obtaining
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# a copy of this software and associated documentation files (the
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# "Software"), to deal in the Software without restriction, including
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# without limitation the rights to use, copy, modify, merge, publish,
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# distribute, sublicense, and/or sell copies of the Software, and to
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# permit persons to whom the Software is furnished to do so, subject to
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# the following conditions:
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#
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# The above copyright notice and this permission notice shall be
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# included in all copies or substantial portions of the Software.
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#
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# THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
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# EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
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# MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
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# NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
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# LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
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# OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
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# WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
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#
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################################################################################
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class PDF::Reader
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################################################################################
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# An internal PDF::Reader class that reads objects from the PDF file and converts
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# them into useable ruby objects (hash's, arrays, true, false, etc)
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class Parser
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TOKEN_STRATEGY = proc { |parser, token| Token.new(token) }
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STRATEGIES = {
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"/" => proc { |parser, token| parser.send(:pdf_name) },
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"<<" => proc { |parser, token| parser.send(:dictionary) },
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"[" => proc { |parser, token| parser.send(:array) },
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"(" => proc { |parser, token| parser.send(:string) },
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"<" => proc { |parser, token| parser.send(:hex_string) },
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nil => proc { nil },
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"true" => proc { true },
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"false" => proc { false },
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"null" => proc { nil },
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"obj" => TOKEN_STRATEGY,
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"endobj" => TOKEN_STRATEGY,
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"stream" => TOKEN_STRATEGY,
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"endstream" => TOKEN_STRATEGY,
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">>" => TOKEN_STRATEGY,
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"]" => TOKEN_STRATEGY,
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">" => TOKEN_STRATEGY,
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")" => TOKEN_STRATEGY
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}
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################################################################################
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# Create a new parser around a PDF::Reader::Buffer object
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#
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# buffer - a PDF::Reader::Buffer object that contains PDF data
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# objects - a PDF::Reader::ObjectHash object that can return objects from the PDF file
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def initialize(buffer, objects=nil)
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@buffer = buffer
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@objects = objects
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end
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################################################################################
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# Reads the next token from the underlying buffer and convets it to an appropriate
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# object
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#
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# operators - a hash of supported operators to read from the underlying buffer.
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def parse_token(operators={})
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token = @buffer.token
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if STRATEGIES.has_key? token
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STRATEGIES[token].call(self, token)
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elsif token.is_a? PDF::Reader::Reference
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token
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elsif operators.has_key? token
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Token.new(token)
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elsif token.frozen?
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token
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elsif token =~ /\d*\.\d/
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token.to_f
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else
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token.to_i
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end
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end
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################################################################################
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# Reads an entire PDF object from the buffer and returns it as a Ruby String.
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# If the object is a content stream, returns both the stream and the dictionary
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# that describes it
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#
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# id - the object ID to return
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# gen - the object revision number to return
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def object(id, gen)
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idCheck = parse_token
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# Sometimes the xref table is corrupt and points to an offset slightly too early in the file.
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# check the next token, maybe we can find the start of the object we're looking for
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if idCheck != id
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Error.assert_equal(parse_token, id)
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end
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Error.assert_equal(parse_token, gen)
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Error.str_assert(parse_token, "obj")
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obj = parse_token
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post_obj = parse_token
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if obj.is_a?(Hash) && post_obj == "stream"
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stream(obj)
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else
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obj
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end
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end
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private
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################################################################################
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# reads a PDF dict from the buffer and converts it to a Ruby Hash.
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def dictionary
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dict = {}
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loop do
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key = parse_token
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break if key.kind_of?(Token) and key == ">>"
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raise MalformedPDFError, "unterminated dict" if @buffer.empty?
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PDF::Reader::Error.validate_type_as_malformed(key, "Dictionary key", Symbol)
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value = parse_token
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value.kind_of?(Token) and Error.str_assert_not(value, ">>")
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dict[key] = value
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end
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dict
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end
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################################################################################
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# reads a PDF name from the buffer and converts it to a Ruby Symbol
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def pdf_name
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tok = @buffer.token
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tok = tok.dup.gsub(/#([A-Fa-f0-9]{2})/) do |match|
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match[1, 2].hex.chr
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end
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tok.to_sym
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end
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################################################################################
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# reads a PDF array from the buffer and converts it to a Ruby Array.
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def array
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a = []
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loop do
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item = parse_token
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break if item.kind_of?(Token) and item == "]"
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raise MalformedPDFError, "unterminated array" if @buffer.empty?
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a << item
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end
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a
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end
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################################################################################
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# Reads a PDF hex string from the buffer and converts it to a Ruby String
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def hex_string
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str = "".dup
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loop do
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token = @buffer.token
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break if token == ">"
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raise MalformedPDFError, "unterminated hex string" if @buffer.empty?
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str << token
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end
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# add a missing digit if required, as required by the spec
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str << "0" unless str.size % 2 == 0
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[str].pack('H*')
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end
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################################################################################
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# Reads a PDF String from the buffer and converts it to a Ruby String
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def string
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str = @buffer.token
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return "".dup.force_encoding("binary") if str == ")"
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Error.assert_equal(parse_token, ")")
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str.gsub!(/\\(\r\n|[nrtbf()\\\n\r]|([0-7]{1,3}))?|\r\n?/m) do |match|
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if $2.nil? # not octal digits
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MAPPING[match] || "".dup
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else # must be octal digits
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($2.oct & 0xff).chr # ignore high level overflow
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end
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end
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str.force_encoding("binary")
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end
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MAPPING = {
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"\r" => "\n",
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"\r\n" => "\n",
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"\\n" => "\n",
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"\\r" => "\r",
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"\\t" => "\t",
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"\\b" => "\b",
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"\\f" => "\f",
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"\\(" => "(",
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"\\)" => ")",
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"\\\\" => "\\",
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"\\\n" => "",
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"\\\r" => "",
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"\\\r\n" => "",
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}
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################################################################################
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# Decodes the contents of a PDF Stream and returns it as a Ruby String.
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def stream(dict)
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raise MalformedPDFError, "PDF malformed, missing stream length" unless dict.has_key?(:Length)
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if @objects
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length = @objects.deref_integer(dict[:Length])
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if dict[:Filter]
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dict[:Filter] = @objects.deref_name_or_array(dict[:Filter])
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end
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else
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length = dict[:Length] || 0
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end
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PDF::Reader::Error.validate_type_as_malformed(length, "length", Numeric)
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data = @buffer.read(length, :skip_eol => true)
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Error.str_assert(parse_token, "endstream")
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# We used to assert that the stream had the correct closing token, but it doesn't *really*
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# matter if it's missing, and other readers seems to handle its absence just fine
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# Error.str_assert(parse_token, "endobj")
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PDF::Reader::Stream.new(dict, data)
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end
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################################################################################
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end
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################################################################################
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end
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################################################################################
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