Module: Metaclean::Qpdf

Defined in:
lib/metaclean/qpdf.rb

Class Method Summary collapse

Class Method Details

.available? ⇒ Boolean

Returns:

  • (Boolean) 


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# File 'lib/metaclean/qpdf.rb', line 19

def available?
  return @available if defined?(@available)

  out, _err, status = Open3.capture3('qpdf', '--version')
  @available = status.success?
  # `qpdf --version` prints "qpdf version 11.9.0" on its first line. We
  # keep just the bare number (`.split.last`) so callers don't each have
  # to post-process it — matching Exiftool.version / Mat2.version. Captured
  # here so `version` reuses it instead of re-spawning the binary.
  @version = @available ? out.lines.first.to_s.strip.split.last : nil
  @available
rescue Errno::ENOENT
  @version = nil
  @available = false
end

.rebuild!(path) ⇒ Object

Rebuilds a PDF in place. The qpdf flags here:

--linearize                          → optimize for streaming/web
--object-streams=generate            → bundle objects efficiently
--remove-unreferenced-resources=yes  → drop unused content (the
                                        privacy-relevant part!)

qpdf can’t write back to the same file, so we use the standard “atomic write” pattern: write to a temp file, then rename it on top of the original. ‘File.rename` (used internally by `FileUtils.mv` for same-filesystem moves) is atomic on POSIX — either the swap completes or nothing changes. No “half-written” state is ever visible.



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# File 'lib/metaclean/qpdf.rb', line 50

def rebuild!(path)
  raise Error, 'qpdf not available' unless available?

  src = Metaclean.safe_path(path)
  # SecureRandom (not PID alone) makes the temp name unpredictable, so a
  # hostile process sharing the directory can't pre-create the path as a
  # symlink that qpdf would then write through.
  tmp = "#{src}.qpdf.tmp.#{SecureRandom.hex(8)}"

  _out, err, status = Open3.capture3(
    'qpdf', '--linearize', '--object-streams=generate',
    '--remove-unreferenced-resources=yes', src, tmp
  )

  # qpdf has a quirk: exit code 3 means "succeeded with warnings" (output
  # is still produced and valid). We treat that the same as success.
  success = status.success? || status.exitstatus == 3
  raise Error, "qpdf failed: #{err.strip}" unless success

  FileUtils.mv(tmp, src)
  true
ensure
  # Interrupt-safety: drop the temp if we died (or failed) before the
  # rename. On success it's already moved, so this is a no-op.
  File.delete(tmp) if tmp && File.exist?(tmp)
end

.version ⇒ Object 



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# File 'lib/metaclean/qpdf.rb', line 35

def version
  available? ? @version : nil
end