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Check signals during unbounded FileIO reads #9571

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Merged
youknowone merged 3 commits into from
Nov 6, 2026
Merged

Check signals during unbounded FileIO reads #9571

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907c0d3
Check Python signals during unbounded FileIO reads
youknowdot Nov 3, 2026
a7d3685
Use checked conversion for FileIO growth limit
youknowdot Nov 3, 2026
2bdcf74
Retire the passing FileIO signal-interruption marker
codex Nov 6, 2026
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4 changes: 0 additions & 4 deletions Lib/test/test_file_eintr.py
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Original file line number Diff line number Diff line change
Expand Up @@ -186,10 +186,6 @@ def test_readall(self):
class CTestFileIOSignalInterrupt(TestFileIOSignalInterrupt, unittest.TestCase):
modname = '_io'

@unittest.expectedFailure # TODO: RUSTPYTHON; - _io.FileIO.readall uses read_to_end which differs from _pyio.FileIO.readall
def test_readall(self):
return super().test_readall()

class PyTestFileIOSignalInterrupt(TestFileIOSignalInterrupt, unittest.TestCase):
modname = '_pyio'

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40 changes: 24 additions & 16 deletions crates/vm/src/stdlib/_io.rs
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Expand Up @@ -6417,25 +6417,33 @@ mod fileio {
bytes.shrink_to_fit();
bytes
} else {
let mut bytes = vec![];
// Loop on EINTR (PEP 475)
let mut bytes = Vec::new();
let mut used = 0;
// Read one syscall at a time so EINTR reaches the Python
// signal handler instead of being retried inside read_to_end.
loop {
match vm.allow_threads(|| host_io::read_all(handle, &mut bytes)) {
Ok(()) => break,
Err(e) if host_io::is_interrupted_error(&e) => {
vm.check_signals()?;
continue;
}
// Non-blocking mode: return None if EAGAIN (only if no data read yet)
Err(e) if host_io::is_would_block_error(&e) => {
if bytes.is_empty() {
return Ok(None);
}
break;
}
Err(e) => return Err(FileIO::io_error(zelf, e, vm)),
if used == bytes.len() {
// Match FileIO's amortized growth while leaving at least
// one byte for the read that detects EOF.
let growth = if used > 65_536 { used >> 3 } else { used + 256 }.max(8192);
let size = used.checked_add(growth).filter(|&n| isize::try_from(n).is_ok())
.ok_or_else(|| vm.new_overflow_error(
"unbounded read returned more bytes than a Python bytes object can hold"
))?;
bytes
.try_reserve_exact(growth)
.map_err(|_| vm.no_memory_error())?;
bytes.resize(size, 0);
}
match FileIO::read_once_into(zelf, handle, &mut bytes[used..], vm)? {

@chatgpt-codex-connector chatgpt-codex-connector Bot Nov 3, 2026

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P1 Badge Retire the expected-failure marker for the repaired EINTR test

On POSIX, the signal-aware call now lets the read() phase of CTestFileIOSignalInterrupt.test_readall complete, but Lib/test/test_file_eintr.py:189 still decorates the entire test with @unittest.expectedFailure. Consequently, a correct run is recorded as an unexpected success, which Lib/unittest/result.py::wasSuccessful and the regrtest runner treat as a failing suite. Validate the repaired test and remove its obsolete decorator/TODO alongside this fix so that test_file_eintr can pass.

AGENTS.md reference: AGENTS.md:L100-L100

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Some(0) => break,
Some(n) => used += n,
None if used == 0 => return Ok(None),
None => break,
}
}
bytes.truncate(used);
bytes.shrink_to_fit();
bytes
};

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