Module: Pdfrb::Source::TrailerReader

Defined in:
lib/pdfrb/source/trailer_reader.rb

Overview

Locates startxref near EOF and returns its offset. Per s7.5.5, the last startxref keyword in the file is authoritative.

Constant Summary collapse

SCAN_BYTES = 
1024

Class Method Summary collapse

Class Method Details

.startxref_offset(io) ⇒ Object

Returns the byte offset of the xref section (the value of the last startxref keyword in the file), or nil if not found.



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# File 'lib/pdfrb/source/trailer_reader.rb', line 14

def startxref_offset(io)
  size = io.size
  back = [SCAN_BYTES, size].min
  io.seek(size - back, IO::SEEK_SET)
  tail = io.read(back)
  return nil unless tail

  idx = tail.rindex("startxref")
  return nil unless idx

  rest = tail[(idx + "startxref".length)..]
  m = rest.match(/(\d+)/)
  return nil unless m

  m[1].to_i
end