ENH: Add PdfReader.xfa attribute (#1026)

Closes #408

Co-authored-by: George Alverson <[email protected]>

PyPDF2/_reader.py

@@ -31,6 +31,7 @@
 import re
 import struct
 import warnings
+import zlib
 from io import BytesIO
 from pathlib import Path
 from typing import (
@@ -1638,6 +1639,30 @@ def isEncrypted(self) -> bool:  # pragma: no cover
         deprecate_with_replacement("isEncrypted", "is_encrypted")
         return self.is_encrypted
 
+    @property
+    def xfa(self) -> Optional[Dict[str, Any]]:
+        tree: Optional[TreeObject] = None
+        retval: Dict[str, Any] = {}
+        catalog = cast(DictionaryObject, self.trailer[TK.ROOT])
+
+        if "/AcroForm" not in catalog or not catalog["/AcroForm"]:
+            return None
+
+        tree = cast(TreeObject, catalog["/AcroForm"])
+
+        if "/XFA" in tree:
+            fields = cast(ArrayObject, tree["/XFA"])
+            i = iter(fields)
+            for f in i:
+                tag = f
+                f = next(i)
+                if isinstance(f, IndirectObject):
+                    field = cast(Optional[EncodedStreamObject], f.get_object())
+                    if field:
+                        es = zlib.decompress(field._data)
+                        retval[tag] = es
+        return retval
+
 
 class PdfFileReader(PdfReader):  # pragma: no cover
     def __init__(self, *args: Any, **kwargs: Any) -> None:

tests/test_reader.py

@@ -821,6 +821,32 @@ def test_unexpected_destination():
     assert exc.value.args[0] == "Unexpected destination '/1'"
 
 
+@pytest.mark.parametrize(
+    "src",
+    [
+        (os.path.join(RESOURCE_ROOT, "crazyones.pdf")),
+        (os.path.join(RESOURCE_ROOT, "commented.pdf")),
+    ],
+)
+def test_xfa(src):
+    reader = PdfReader(src)
+    assert reader.xfa is None
+
+
+def test_xfa_non_empty():
+    url = "https://corpora.tika.apache.org/base/docs/govdocs1/942/942050.pdf"
+    name = "tika-942050.pdf"
+    reader = PdfReader(BytesIO(get_pdf_from_url(url, name=name)))
+    assert list(reader.xfa.keys()) == [
+        "preamble",
+        "config",
+        "template",
+        "PDFSecurity",
+        "datasets",
+        "postamble",
+    ]
+
+
 @pytest.mark.parametrize(
     "src,pdf_header",
     [