bug(sort): when the pipe sends $'hello' without any \n, sort ignore the requests

[HackingRepo]

Hi, uutils mainteners

we confirmed the uu sort, when the pipe send $'hello' with no \n, it ignores the request

as our test confirms

relunsec@relunsec:~/software/coreutils/target/debug$ ./sort pipe

and open a new terminal

relunsec@relunsec:~/software/coreutils/target/debug$ echo -n $'hello' > pipe
relunsec@relunsec:~/software/coreutils/target/debug$ 

as you can see sort ignore the data the pipe says and wait,

while doping the samething for gnu one

relunsec@relunsec:~/software/coreutils/target/debug$ gnusort pipe

and switch to the second terminal and then type the command again

relunsec@relunsec:~/software/coreutils/target/debug$ echo -n $'hello' > pipe
relunsec@relunsec:~/software/coreutils/target/debug$ 

you will see

relunsec@relunsec:~/software/coreutils/target/debug$ gnusort pipe
hello
relunsec@relunsec:~/software/coreutils/target/debug$ 

the gnu one successfully receive the data

[hiSandog]

This would be clearer with a minimal command that does not depend on an interactive pipe setup, for example comparing printf hello | ./sort with GNU sort. The important compatibility point is that EOF without a trailing newline should still emit the final record, not wait for or discard it. A regression test around stdin with no final \n would cover the behavior directly.

[HackingRepo]

@hiSandog however

relunsec@relunsec:~/software/coreutils/target/debug$ printf hello | ./sort
hello
relunsec@relunsec:~/software/coreutils/target/debug$ 

with just simple your example will work, we need cover a test for a pipe, just standard printf will work fine

[HackingRepo]

maybe a test case like

#[test]
fn test_named_pipe_unterminated_line() {
    let temp_dir = tempdir().unwrap();
    let fifo_path = temp_dir.path().join("test_sort_fifo");
    nix::unistd::mkfifo(&fifo_path, nix::sys::stat::Mode::S_IRWXU).unwrap();

    // 2. Launch uutils sort in a background thread targeting the FIFO
    let mut cmd = new_ucmd!();
    let mut child = cmd.arg(&fifo_path).spawn().unwrap();

    {
        let mut writer = std::fs::OpenOptions::new().write(true).open(&fifo_path).unwrap();
        writer.write_all(b"hello").unwrap();
    }

    let status = child.wait_timeout(Duration::from_secs(2)).unwrap();
    assert!(status.is_some(), "Sort entered an infinite hang loop on unterminated pipe input!");
}