BUG: Don't close stream passed to PdfWriter.write()

pypdf/_writer.py

@@ -235,9 +235,9 @@ def _get_clone_from(
                 or Path(str(fileobj)).stat().st_size == 0
             ):
                 cloning = False
-            if isinstance(fileobj, (IO, BytesIO)):
+            if isinstance(fileobj, (IOBase, BytesIO)):
                 t = fileobj.tell()
-                fileobj.seek(-1, 2)
+                fileobj.seek(0, 2)
                 if fileobj.tell() == 0:
                     cloning = False
                 fileobj.seek(t, 0)
@@ -249,7 +249,7 @@ def _get_clone_from(
         # to prevent overwriting
         self.temp_fileobj = fileobj
         self.fileobj = ""
-        self.with_as_usage = False
+        self.cloned = False
         # The root of our page tree node.
         pages = DictionaryObject()
         pages.update(
@@ -267,6 +267,7 @@ def _get_clone_from(
             if not isinstance(clone_from, PdfReader):
                 clone_from = PdfReader(clone_from)
             self.clone_document_from_reader(clone_from)
+            self.cloned = True
         else:
             self._pages = self._add_object(pages)
             # root object
@@ -353,10 +354,11 @@ def xmp_metadata(self, value: Optional[XmpInformation]) -> None:
         return self.root_object.xmp_metadata  # type: ignore
 
     def __enter__(self) -> "PdfWriter":
-        """Store that writer is initialized by 'with'."""
+        """Store how writer is initialized by 'with'."""
+        c: bool = self.cloned
         t = self.temp_fileobj
         self.__init__()  # type: ignore
-        self.with_as_usage = True
+        self.cloned = c
         self.fileobj = t  # type: ignore
         return self
 
@@ -367,7 +369,7 @@ def __exit__(
         traceback: Optional[TracebackType],
     ) -> None:
         """Write data to the fileobj."""
-        if self.fileobj:
+        if self.fileobj and not self.cloned:
             self.write(self.fileobj)
 
     def _repr_mimebundle_(
@@ -1388,13 +1390,14 @@ def write(self, stream: Union[Path, StrByteType]) -> Tuple[bool, IO[Any]]:
 
         if isinstance(stream, (str, Path)):
             stream = FileIO(stream, "wb")
-            self.with_as_usage = True  #
             my_file = True
 
         self.write_stream(stream)
 
-        if self.with_as_usage:
+        if my_file:
             stream.close()
+        else:
+            stream.flush()
 
         return my_file, stream
 

tests/test_writer.py

@@ -2480,3 +2480,32 @@ def test_append_pdf_with_dest_without_page(caplog):
     writer.append(reader)
     assert "/__WKANCHOR_8" not in writer.named_destinations
     assert len(writer.named_destinations) == 3
+
+
+def test_stream_not_closed():
+    """Tests for #2905"""
+    src = RESOURCE_ROOT / "pdflatex-outline.pdf"
+    with NamedTemporaryFile(suffix=".pdf") as tmp:
+        with PdfReader(src) as reader, PdfWriter() as writer:
+            writer.add_page(reader.pages[0])
+            writer.write(tmp)
+        assert not tmp.file.closed
+
+    with NamedTemporaryFile(suffix=".pdf") as target:
+        with PdfWriter(target.file) as writer:
+            writer.add_blank_page(100, 100)
+        assert not target.file.closed
+
+    with open(src, "rb") as fileobj:
+        with PdfWriter(fileobj) as writer:
+            pass
+        assert not fileobj.closed
+
+
+def test_auto_write():
+    """Another test for #2905"""
+    target = Path(_get_write_target(str))
+    with PdfWriter(target) as writer:
+        writer.add_blank_page(100, 100)
+    assert target.stat().st_size > 0
+    target.unlink()