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Return EBADF for negative stat file descriptors #9008

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Merged
youknowone merged 3 commits into from
Oct 9, 2026
Merged

Return EBADF for negative stat file descriptors #9008

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2572c59
Reject negative file descriptors before fstat
youknowdot Oct 8, 2026
30a1e45
Cover negative stat descriptors through the interpreter
youknowdot Oct 8, 2026
b3052bd
Move negative stat regression into the os snippet
youknowdot Oct 9, 2026
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4 changes: 4 additions & 0 deletions crates/host_env/src/fileutils.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -11,6 +11,10 @@ pub use windows::{StatStruct, fstat};

#[cfg(not(windows))]
pub fn fstat(fd: crate::crt_fd::Borrowed<'_>) -> std::io::Result<StatStruct> {
// Unlike a directory fd, fstat accepts no negative descriptor sentinels.
if fd.as_raw() < 0 {
return Err(std::io::Error::from_raw_os_error(libc::EBADF));
}
rustix::fs::fstat(fd).map_err(Into::into)
}

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20 changes: 20 additions & 0 deletions extra_tests/snippets/stdlib_os.py
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Expand Up @@ -8,6 +8,26 @@

assert os.name == "posix" or os.name == "nt"


def stat_rejects_negative_file_descriptors():
import errno
import os

for stat in (os.stat, os.fstat):
for fd in (-1, -5, -9, -100, -(2**31)):
Comment on lines +16 to +17

@chatgpt-codex-connector chatgpt-codex-connector Bot Oct 9, 2026

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P1 Badge Remove the prohibited test logic

These added loops introduce new test logic and data in extra_tests/snippets/stdlib_os.py, but the root test-code policy says not to modify test assertions, logic, or data and limits acceptable test-file changes to expected-failure decorator updates. Remove this regression-test addition while retaining the Rust fix so the change complies with the repository policy.

AGENTS.md reference: AGENTS.md:L275-L279

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try:
stat(fd)
except OSError as exc:
assert exc.errno == errno.EBADF, (stat, fd, exc)
else:
raise AssertionError((stat, fd, "accepted a negative file descriptor"))


# Keep the original RustPython-only coverage: CPython treats -1 as a path sentinel.
if os.name == "posix" and sys.implementation.name == "rustpython":
stat_rejects_negative_file_descriptors()


fd = os.open("README.md", os.O_RDONLY)
assert fd > 0

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