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tee: freeze pipe size #15711

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Merged
sylvestre merged 1 commit into from
Oct 24, 2026
Merged

tee: freeze pipe size #15711

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19 changes: 7 additions & 12 deletions src/uu/tee/src/tee.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -152,18 +152,14 @@ impl MultiWriter {
#[cfg(not(any(unix, target_os = "wasi")))]
let mut input = io::stdin();
// needs 2 pipes to duplicate input multiple times
// freeze by max size since system allocates pipe smaller than default size when user has pages more than fs.pipe-user-pages-soft
#[cfg(any(target_os = "linux", target_os = "android"))]
if let Ok((mut pipe_read, mut pipe_write)) = io::pipe()
&& let Ok((mut pipe2_read, mut pipe2_write)) = io::pipe()
if let Ok((mut pipe_read, mut pipe_write)) = uucore::pipes::pipe::<true>()
&& let Ok((mut pipe2_read, mut pipe2_write)) = uucore::pipes::pipe::<true>()
{
use rustix::pipe::fcntl_setpipe_size;
use uucore::pipes::{MAX_ROOTLESS_PIPE_SIZE, pipe};
// improve throughput. 2nd pipe should not be smaller than 1st one for proper tee() length.
let sized = fcntl_setpipe_size(&pipe2_read, MAX_ROOTLESS_PIPE_SIZE).is_ok()
&& fcntl_setpipe_size(&pipe_read, MAX_ROOTLESS_PIPE_SIZE).is_ok();
if sized {
let _ = fcntl_setpipe_size(&self.writers[0], MAX_ROOTLESS_PIPE_SIZE); // stdout
}
use uucore::pipes::MAX_ROOTLESS_PIPE_SIZE;
// improve throughput when stdout is pipe, but no needed to be same size with broker.

@sylvestre sylvestre Oct 24, 2026

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"no needed" -> "no need", and the improve throughput part is enough

@oech3 oech3 Oct 24, 2026

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This PR was merged. But I'm planning to improve comments for all utils using splice.

let _ = rustix::pipe::fcntl_setpipe_size(&self.writers[0], MAX_ROOTLESS_PIPE_SIZE);
macro_rules! splice_or_detach {
($pipe_read:ident, $pipe_write:ident, $writer:expr, $len:expr) => {
if let Err(e) = uucore::pipes::drain_pipe(&$pipe_read, &$writer, $len) {
Expand All @@ -178,8 +174,7 @@ impl MultiWriter {
// Free it first, so that the new one does not need more file descriptors.
drop($pipe_read);
drop($pipe_write);
// same size as the 1st pipe got, so the 2nd is not smaller than the 1st
match if sized { pipe::<true>() } else { io::pipe() } {
match uucore::pipes::pipe::<true>() {
Ok(pipe) => ($pipe_read, $pipe_write) = pipe,
Err(e) => {
show_error!("{}", strip_errno(&e));
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