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csv: reject reentrant reader advancement #8324

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Merged
youknowone merged 3 commits into from
Jul 20, 2026
+15 −4
Merged

csv: reject reentrant reader advancement #8324

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25732c1
csv: reject reentrant reader advancement
widehyo1 Jul 14, 2026
0d0f6fb
csv: invalidate outer reads after reentry
widehyo1 Jul 19, 2026
298bb36
csv: generation type conversion(usize to u64)
widehyo1 Jul 19, 2026
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1 change: 0 additions & 1 deletion Lib/test/test_csv.py
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Original file line number Diff line number Diff line change
Expand Up @@ -568,7 +568,6 @@ def test_roundtrip_escaped_unquoted_newlines(self):
self.assertEqual(row, rows[i])


@unittest.expectedFailure # TODO: RUSTPYTHON; AssertionError: Error not raised
def test_reader_reentrant_iterator(self):
# gh-145105: re-entering the reader from the iterator must not crash.
class ReentrantIter:
Expand Down
18 changes: 15 additions & 3 deletions crates/stdlib/src/csv.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -411,6 +411,7 @@ mod _csv {
skipinitialspace: options.get_skipinitialspace(),
delimiter: options.get_delimiter(),
line_num: 0,
generation: 0,
}),
dialect: options.result(vm)?,
})
Expand Down Expand Up @@ -961,6 +962,7 @@ mod _csv {
skipinitialspace: bool,
delimiter: u8,
line_num: u64,
generation: u64,
}

#[pyclass(no_attr, module = "_csv", name = "reader", traverse)]
Expand Down Expand Up @@ -1057,8 +1059,18 @@ mod _csv {

impl IterNext for Reader {
fn next(zelf: &Py<Self>, vm: &VirtualMachine) -> PyResult<PyIterReturn> {
let string = raise_if_stop!(zelf.iter.next(vm)?);
let string = string.downcast::<PyStr>().map_err(|obj| {
let generation = zelf.state.lock().generation;
let string_obj = raise_if_stop!(zelf.iter.next(vm)?);
let mut state = zelf.state.lock();
if state.generation != generation {
return Err(new_csv_error(
vm,
"iterator has already advanced the reader",
));
}
state.generation += 1;

let string = string_obj.downcast::<PyStr>().map_err(|obj| {
new_csv_error(
vm,
format!(
Expand All @@ -1071,14 +1083,14 @@ mod _csv {
if input.is_empty() || input.starts_with(b"\n") {
return Ok(PyIterReturn::Return(vm.ctx.new_list(vec![]).into()));
}
let mut state = zelf.state.lock();
let ReadState {
buffer,
output_ends,
reader,
skipinitialspace,
delimiter,
line_num,
generation: _,
} = &mut *state;

let mut input_offset = 0;
Expand Down
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