fix #426: Flash reads AES PDFs and guards lazy PyPDF2 failures

pageindex/flash/parser_pdfium_charlevel/pdf_objects.py

@@ -105,10 +105,16 @@ def get_fonts(self, full: bool = True):
 class _PdfDoc:
     """PyPDF2-backed adapter for raw object and stream access PDFium cannot expose."""
 
-    __slots__ = ("_reader", "_virtual")
+    __slots__ = ("_reader", "_virtual", "_page_count")
 
     def __init__(self, reader):
         self._reader = reader
+        # PyPDF2 parses lazily, so a document it cannot read (AES without the
+        # crypto backend, damaged xref) raises on first object access rather
+        # than at PdfReader(). Resolving the page tree here keeps that failure
+        # inside the callers' guarded open, which is what lets them fall back
+        # to the PDFium-only channel instead of propagating.
+        self._page_count = len(reader.pages)
         # Negative pseudo-xrefs for DIRECT (inline) dicts that have no object
         # number -- text extraction reference resolution treats direct and indirect values alike,
         # so inline font dicts must be addressable by the same integer-keyed
@@ -122,7 +128,7 @@ def register_virtual(self, obj) -> int:
 
     @property
     def page_count(self) -> int:
-        return len(self._reader.pages)
+        return self._page_count
 
     def __getitem__(self, idx):
         return _PdfPage(self._reader.pages[idx])

pyproject.toml

@@ -32,6 +32,7 @@ openai = ">=1.70.0"
 openai-agents = ">=0.18.1"
 litellm = ">=1.97.0"
 PyPDF2 = ">=3.0.0"
+pycryptodome = ">=3.15.0"
 pypdfium2 = ">=5"
 sortedcontainers = ">=2.4.0"
 regex = ">=2024.0.0"

requirements.txt

@@ -3,6 +3,7 @@ openai>=1.70.0
 requests>=2.28.0
 openai-agents>=0.18.1
 # pymupdf  # optional
+pycryptodome==3.23.0
 PyPDF2==3.0.1
 pypdfium2==5.13.0
 python-dotenv==1.2.2

tests/test_issue_426.py

@@ -0,0 +1,53 @@
+"""PyPDF2's lazy parse must fail inside the callers' guarded open (#426).
+
+An AES-encrypted PDF raises DependencyError on first object access, not at
+PdfReader(), so the guard around the PyPDF2 open used to miss it and the
+error surfaced from _page_pass1's page_count instead — an unhandled crash on
+a document PDFium reads fine on its own.
+"""
+import pytest
+
+from PyPDF2.errors import DependencyError
+
+
+class _LazyBombReader:
+    """A reader that parses lazily and fails on first object access, the way
+    an AES-encrypted document does without the crypto backend installed."""
+
+    @property
+    def pages(self):
+        raise DependencyError("PyCryptodome is required for AES algorithm")
+
+
+def test_pdf_doc_open_fails_at_construction():
+    """_PdfDoc resolves the page tree eagerly, so an unreadable document
+    raises where both callers already guard the open (the sequential pipeline
+    and the parallel worker init) rather than at first page_count."""
+    from pageindex.flash.parser_pdfium_charlevel.pdf_objects import _PdfDoc
+
+    with pytest.raises(DependencyError):
+        _PdfDoc(_LazyBombReader())
+
+
+def test_flash_falls_back_to_pdfium_when_pypdf2_channel_is_unreadable(
+        sample_pdf, monkeypatch):
+    """The PyPDF2 channel only refines what PDFium already extracts, so losing
+    it degrades the parse instead of failing the run."""
+    from pageindex.flash import page_index_flash
+    from pageindex.flash.parser_pdfium_charlevel import pipeline
+
+    baseline = page_index_flash(sample_pdf, summary=False, optimize=False)
+
+    opened = []
+
+    class _BombingPyPDF2:
+        @staticmethod
+        def PdfReader(*args, **kwargs):
+            opened.append(args)
+            return _LazyBombReader()
+
+    monkeypatch.setattr(pipeline, "_pypdf2", _BombingPyPDF2)
+    degraded = page_index_flash(sample_pdf, summary=False, optimize=False)
+
+    assert opened, "the PyPDF2 channel never opened; the fallback went untested"
+    assert degraded == baseline