James R. Barlow
015b53ae30
Adobe Acrobat can embed a proprietary full-text search index in the document catalog at /Root/PieceInfo/SearchIndex. Only Acrobat reads it; other viewers ignore it and search the text on the fly. Any change to a PDF invalidates the index, so once OCRmyPDF rewrites the document the retained index is stale and returns incorrect search results in Acrobat. OcrGrafter.finalize() now discards it before saving (covering both the OCR and hOCR pipelines), preserving any other PieceInfo owner data and dropping an empty PieceInfo. Modern viewers rebuild a search index on demand, so there is no loss of search capability.
102 lines
3.3 KiB
Python
102 lines
3.3 KiB
Python
# SPDX-FileCopyrightText: 2024 James R. Barlow
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# SPDX-License-Identifier: MPL-2.0
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from __future__ import annotations
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import logging
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import pikepdf
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import pytest
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from pikepdf import Dictionary, Name, String
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from ocrmypdf._graft import discard_text_search_index
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from .conftest import check_ocrmypdf
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# pylint: disable=redefined-outer-name
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def _add_search_index(pdf: pikepdf.Pdf, *, other_owner: bool = False) -> None:
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"""Attach an Adobe-style embedded search index to the document catalog."""
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pieceinfo = Dictionary(
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SearchIndex=Dictionary(
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LastModified=String("D:20240101000000Z"),
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Private=Dictionary(IndexFile=String("dummy.pdx")),
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)
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)
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if other_owner:
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pieceinfo[Name.SomeOtherApp] = Dictionary(
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LastModified=String("D:20240101000000Z")
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)
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pdf.Root.PieceInfo = pdf.make_indirect(pieceinfo)
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def test_discard_text_search_index_removes_only_search_index(resources):
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with pikepdf.open(resources / 'francais.pdf') as pdf:
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# No PieceInfo at all -> nothing to do
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assert not discard_text_search_index(pdf)
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_add_search_index(pdf, other_owner=True)
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assert discard_text_search_index(pdf), "Expected file to be modified"
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# SearchIndex gone, but the other application's private data is preserved
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assert Name.SearchIndex not in pdf.Root.PieceInfo
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assert Name.SomeOtherApp in pdf.Root.PieceInfo
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# Idempotent: a second call finds nothing to remove
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assert not discard_text_search_index(pdf)
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def test_discard_text_search_index_drops_empty_pieceinfo(resources):
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with pikepdf.open(resources / 'francais.pdf') as pdf:
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_add_search_index(pdf, other_owner=False)
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assert discard_text_search_index(pdf)
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# PieceInfo held only the SearchIndex, so the whole husk is removed
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assert Name.PieceInfo not in pdf.Root
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def test_discard_text_search_index_tolerates_malformed_pieceinfo(resources):
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with pikepdf.open(resources / 'francais.pdf') as pdf:
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pdf.Root.PieceInfo = String("not a dictionary")
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assert not discard_text_search_index(pdf)
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@pytest.fixture
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def pdf_with_search_index(resources, outdir):
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out = outdir / 'with_search_index.pdf'
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with pikepdf.open(resources / 'graph.pdf') as pdf:
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_add_search_index(pdf, other_owner=False)
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assert Name.SearchIndex in pdf.Root.PieceInfo
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pdf.save(out)
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return out
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def test_search_index_discarded_end_to_end(pdf_with_search_index, outpdf, caplog):
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caplog.set_level(logging.DEBUG)
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check_ocrmypdf(
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pdf_with_search_index,
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outpdf,
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'--output-type',
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'pdf',
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'--plugin',
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'tests/plugins/tesseract_noop.py',
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)
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with pikepdf.open(outpdf) as pdf:
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assert Name.PieceInfo not in pdf.Root
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assert 'search index' in caplog.text.lower()
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def test_search_index_discarded_with_ocr_engine_none(pdf_with_search_index, outpdf):
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# Even in pure image-processing mode, OCRmyPDF rewrites the PDF, which
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# invalidates the embedded index, so it must still be discarded.
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check_ocrmypdf(
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pdf_with_search_index,
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outpdf,
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'--ocr-engine',
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'none',
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'--output-type',
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'pdf',
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)
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with pikepdf.open(outpdf) as pdf:
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assert Name.PieceInfo not in pdf.Root
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