ROB : some attributes not copied

fixes py-pdf#1615 "/N" attributes wrongly ignored
pubpub-zz · Feb 15, 2023 · 1f0f102 · 1f0f102
1 parent 4bf3e32
commit 1f0f102
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Showing 2 changed files with 39 additions and 5 deletions.
diff --git a/pypdf/generic/_data_structures.py b/pypdf/generic/_data_structures.py
@@ -194,11 +194,27 @@ def _clone(
         """
         #  First check if this is a chain list, we need to loop to prevent recur
         if (
-            ("/Next" not in ignore_fields and "/Next" in src)
-            or ("/Prev" not in ignore_fields and "/Prev" in src)
+            (
+                "/Next" not in ignore_fields
+                and "/Next" in src
+                and isinstance(src.raw_get("/Next"), IndirectObject)
+            )
+            or (
+                "/Prev" not in ignore_fields
+                and "/Prev" in src
+                and isinstance(src.raw_get("/Prev"), IndirectObject)
+            )
         ) or (
-            ("/N" not in ignore_fields and "/N" in src)
-            or ("/V" not in ignore_fields and "/V" in src)
+            (
+                "/N" not in ignore_fields
+                and "/N" in src
+                and isinstance(src.raw_get("/N"), IndirectObject)
+            )
+            or (
+                "/V" not in ignore_fields
+                and "/V" in src
+                and isinstance(src.raw_get("/V"), IndirectObject)
+            )
         ):
             ignore_fields = list(ignore_fields)
             for lst in (("/Next", "/Prev"), ("/N", "/V")):
@@ -230,7 +246,7 @@ def _clone(
                             except Exception:
                                 cur_obj = None
                         for (s, c) in objs:
-                            c._clone(s, pdf_dest, force_duplicate, ignore_fields + [k])
+                            c._clone(s, pdf_dest, force_duplicate, ignore_fields)
 
         for k, v in src.items():
             if k not in ignore_fields:

diff --git a/tests/test_generic.py b/tests/test_generic.py
@@ -1044,3 +1044,21 @@ def test_cloning(caplog):
     obj21 = obj20.clone(writer, ignore_fields=None)
     assert "/Test" in obj21
     assert isinstance(obj21.get("/Test2"), IndirectObject)
+
+
+@pytest.mark.external
+def test_iss1615():
+    """
+    test cases where /N is not indicating chains of objects
+    """
+    url = "https://github.com/py-pdf/pypdf/files/10671366/graph_letter.pdf"
+    name = "graph_letter.pdf"
+    reader = PdfReader(BytesIO(get_pdf_from_url(url, name=name)))
+    writer = PdfWriter()
+    writer.append(reader)
+    assert (
+        "/N"
+        in writer.pages[0]["/Annots"][0]
+        .get_object()["/AP"]["/N"]["/Resources"]["/ColorSpace"]["/Cs1"][1]
+        .get_object()
+    )