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HP Scan invalid Length workaround #215

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HP Scan invalid Length workaround #215

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44cb8af
HP Scan invalid Length workaround
mfazekas May 3, 2022
c450a05
Use check stream length to check and correct stream lengths if needed
mfazekas Nov 15, 2023
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31 changes: 30 additions & 1 deletion lib/combine_pdf/parser.rb
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Original file line number Diff line number Diff line change
Expand Up @@ -34,6 +34,7 @@ class PDFParser
attr_reader :info_object, :root_object, :names_object, :forms_object, :outlines_object, :metadata

attr_reader :allow_optional_content, :raise_on_encrypted
attr_reader :check_stream_length
# when creating a parser, it is important to set the data (String) we wish to parse.
#
# <b>the data is required and it is not possible to set the data at a later stage</b>
Expand All @@ -59,6 +60,7 @@ def initialize(string, options = {})
@scanner = nil
@allow_optional_content = options[:allow_optional_content]
@raise_on_encrypted = options[:raise_on_encrypted]
@check_stream_length = options[:check_stream_length]
end

# parse the data in the new parser (the data already set through the initialize / new method)
Expand Down Expand Up @@ -363,7 +365,11 @@ def _parse_
# advance by the publshed stream length (if any)
old_pos = @scanner.pos
if(out.last.is_a?(Hash) && out.last[:Length].is_a?(Integer) && out.last[:Length] > 2)
@scanner.pos += out.last[:Length] - 2
if @check_stream_length
advance_pos_with_length_check(@scanner, out.last[:Length], out.last)
else
@scanner.pos += out.last[:Length] - 2
end
end

# the following was dicarded because some PDF files didn't have an EOL marker as required
Expand Down Expand Up @@ -507,6 +513,29 @@ def _parse_

protected

def advance_pos_with_length_check(scanner, length, obj)
endstream = 'endstream'
orig_pos = scanner.pos
if scanner.rest_size > length
scanner.pos += length
if scanner.check(endstream)
scanner.pos -= 2
return
end
warn "Invalid length no #{endstream} found - object: #{obj}!"
else
warn "Invalid length in stream points out of the file - object: #{obj}!"
end
scanner.pos = orig_pos
skipped = scanner.skip_until(/endstream/)
if skipped
correct_len = skipped - endstream.length
scanner.pos -= endstream.length + 2
else
raise ParsingError, "Parsing Error: PDF file error - a stream object with invalid length of #{length} for object #{out} and no #{endstream} found after, to work around it"
end
end

# resets cataloging and pages
def catalog_pages(catalogs = nil, inheritance_hash = {})
unless catalogs
Expand Down