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tee: fix poll timeout causing intermittent hangs with -p flag

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Sylvestre Ledru 2025-12-07 00:19:45 +01:00
parent 443c2014fb
commit 62962d3526
1 changed files with 8 additions and 7 deletions
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15
src/uu/tee/src/tee.rs
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@ -443,11 +443,12 @@ pub fn ensure_stdout_not_broken() -> Result<bool> {
// POLLRDBAND is the flag used by GNU tee.
let mut pfds = [PollFd::new(out.as_fd(), PollFlags::POLLRDBAND)];
// Then, ensure that the pipe is not broken
let res = nix::poll::poll(&mut pfds, PollTimeout::NONE)?;
// Then, ensure that the pipe is not broken.
// Use ZERO timeout to return immediately - we just want to check the current state.
let res = nix::poll::poll(&mut pfds, PollTimeout::ZERO)?;
if res > 0 {
// poll succeeded;
// poll returned with events ready - check if POLLERR is set (pipe broken)
let error = pfds.iter().any(|pfd| {
if let Some(revents) = pfd.revents() {
revents.contains(PollFlags::POLLERR)
@ -458,8 +459,8 @@ pub fn ensure_stdout_not_broken() -> Result<bool> {
return Ok(!error);
}
// if res == 0, it means that timeout was reached, which is impossible
// because we set infinite timeout.
// And if res < 0, the nix wrapper should have sent back an error.
unreachable!();
// res == 0 means no events ready (timeout reached immediately with ZERO timeout).
// This means the pipe is healthy (not broken).
// res < 0 would be an error, but nix returns Err in that case.
Ok(true)
}