BUG: Truncate mediabox and cropbox values with > 4 points.

Closes #2991

Author: sjudd

pypdf/_page.py

@@ -106,7 +106,7 @@
 MERGE_CROP_BOX = "cropbox"  # pypdf<=3.4.0 used 'trimbox'
 
 
-def _get_rectangle(self: Any, name: str, defaults: Iterable[str]) -> RectangleObject:
+def _get_rectangle(self: Any, name: str, defaults: Iterable[str], allow_truncate: bool) -> RectangleObject:
     retval: Union[None, RectangleObject, IndirectObject] = self.get(name)
     if isinstance(retval, RectangleObject):
         return retval
@@ -117,6 +117,13 @@ def _get_rectangle(self: Any, name: str, defaults: Iterable[str]) -> RectangleOb
                 break
     if isinstance(retval, IndirectObject):
         retval = self.pdf.get_object(retval)
+    if allow_truncate and (isinstance(retval, list) or isinstance(retval, tuple)):
+        if len(retval) != 4:
+            logger_warning(
+                f"Expected {name} to be a rectangle with 4 points, but found: {retval}",
+                __name__
+            )
+            retval = retval[:4]
     retval = RectangleObject(retval)  # type: ignore
     _set_rectangle(self, name, retval)
     return retval
@@ -131,9 +138,14 @@ def _delete_rectangle(self: Any, name: str) -> None:
     del self[name]
 
 
-def _create_rectangle_accessor(name: str, fallback: Iterable[str]) -> property:
+def _create_rectangle_accessor(name: str, fallback: Iterable[str], allow_truncate: bool = False) -> property:
+    """
+    Params:
+        allow_truncate: True to permissively truncate the value at name down to the 4 points
+        expected by RectangleObject if the value is a Tuple or List with a greater length.
+    """
     return property(
-        lambda self: _get_rectangle(self, name, fallback),
+        lambda self: _get_rectangle(self, name, fallback, allow_truncate=allow_truncate),
         lambda self, value: _set_rectangle(self, name, value),
         lambda self: _delete_rectangle(self, name),
     )
@@ -2452,12 +2464,12 @@ def _get_fonts(self) -> Tuple[Set[str], Set[str]]:
         unembedded = fonts - embedded
         return embedded, unembedded
 
-    mediabox = _create_rectangle_accessor(PG.MEDIABOX, ())
+    mediabox = _create_rectangle_accessor(PG.MEDIABOX, (), allow_truncate=True)
     """A :class:`RectangleObject<pypdf.generic.RectangleObject>`, expressed in
     default user space units, defining the boundaries of the physical medium on
     which the page is intended to be displayed or printed."""
 
-    cropbox = _create_rectangle_accessor("/CropBox", (PG.MEDIABOX,))
+    cropbox = _create_rectangle_accessor("/CropBox", (PG.MEDIABOX,), allow_truncate=True)
     """
     A :class:`RectangleObject<pypdf.generic.RectangleObject>`, expressed in
     default user space units, defining the visible region of default user

tests/test_page.py

@@ -326,6 +326,20 @@ def test_page_properties():
     assert page.bleedbox == RectangleObject((0, 1, 100, 101))
 
 
+@pytest.mark.parametrize("key", [PG.MEDIABOX, PG.CROPBOX])
+@pytest.mark.parametrize("values", [
+    [0, 0, 612, 792, 0, 0, 612, 792],
+    (0, 0, 612, 792, 0, 0, 612, 792),
+    [0, 0, 612, 792, 0, 0, 612, 792, 0, 0],
+    (0, 0, 612, 792, 0, 0, 612, 792, 0, 0),
+])
+def test_page_handles_long_media_and_crop_box_iss_2991(key: str, values: List[float] | Tuple[float, ...]):
+    reader = PdfReader(RESOURCE_ROOT / "crazyones.pdf")
+    page = reader.pages[0]
+    page[NameObject(key)] = ArrayObject(values)
+    assert page.mediabox == RectangleObject((0, 0, 612, 792))
+
+
 def test_page_rotation():
     reader = PdfReader(RESOURCE_ROOT / "crazyones.pdf")
     page = reader.pages[0]