kill: fix GNU compatibility tests for RTMIN and RTMAX (#11224)

* kill: list Linux realtime signals correctly

Add list-specific signal helpers for RTMIN/RTMAX and unnamed
signal numbers, and use them in kill and env range iteration.
Keep send-oriented signal parsing unchanged for signal delivery.

* document low-byte signal decoding in list mode

src/uu/env/src/env.rs

@@ -43,7 +43,7 @@ use uucore::display::{Quotable, print_all_env_vars};
 use uucore::error::{ExitCode, UError, UResult, USimpleError, UUsageError};
 use uucore::line_ending::LineEnding;
 #[cfg(unix)]
-use uucore::signals::{ALL_SIGNALS, signal_by_name_or_value, signal_name_by_value};
+use uucore::signals::{signal_by_name_or_value, signal_name_by_value, signal_number_upper_bound};
 use uucore::translate;
 use uucore::{format_usage, show_warning};
 
@@ -216,7 +216,7 @@ impl SignalRequest {
             f(sig, true)?;
         }
         if self.apply_all {
-            for sig_value in 1..ALL_SIGNALS.len() {
+            for sig_value in 1..=signal_number_upper_bound() {
                 if self.signals.contains(&sig_value) {
                     continue;
                 }

src/uu/kill/src/kill.rs

@@ -13,7 +13,10 @@ use uucore::display::Quotable;
 use uucore::error::{FromIo, UResult, USimpleError};
 use uucore::translate;
 
-use uucore::signals::{ALL_SIGNALS, signal_by_name_or_value, signal_name_by_value};
+use uucore::signals::{
+    signal_by_name_or_value, signal_list_name_by_value, signal_list_value_by_name_or_number,
+    signal_name_by_value, signal_number_upper_bound,
+};
 use uucore::{format_usage, show};
 
 // When the -l option is selected, the program displays the type of signal related to a certain
@@ -159,34 +162,44 @@ fn handle_obsolete(args: &mut Vec<String>) -> Option<usize> {
 }
 
 fn table() {
-    for (idx, signal) in ALL_SIGNALS.iter().enumerate() {
-        println!("{idx: >#2} {signal}");
+    for signal_value in 0..=signal_number_upper_bound() {
+        if let Some(signal_name) = signal_list_name_by_value(signal_value) {
+            println!("{signal_value: >#2} {signal_name}");
+        }
     }
 }
 
-fn print_signal(signal_name_or_value: &str) -> UResult<()> {
-    // Closure used to track the last 8 bits of the signal value
-    // when the -l option is passed only the lower 8 bits are important
-    // or the value is in range [128, 159]
-    // Example: kill -l 143 => TERM because 143 = 15 + 128
-    // Example: kill -l 2304 => EXIT
-    let lower_8_bits = |x: usize| x & 0xff;
-    let option_num_parse = signal_name_or_value.parse::<usize>().ok();
+fn normalize_list_signal_value(signal_value: usize) -> Option<usize> {
+    // `kill -l` also accepts wait-status-like values and decodes the signal
+    // number from the low 8 bits.
+    let lower_8_bits = signal_value & 0xff;
+    if lower_8_bits <= signal_number_upper_bound() {
+        return Some(lower_8_bits);
+    }
 
-    for (value, &signal) in ALL_SIGNALS.iter().enumerate() {
-        if signal.eq_ignore_ascii_case(signal_name_or_value)
-            || format!("SIG{signal}").eq_ignore_ascii_case(signal_name_or_value)
-        {
-            println!("{value}");
-            return Ok(());
-        } else if signal_name_or_value == value.to_string()
-            || option_num_parse.is_some_and(|signal_value| lower_8_bits(signal_value) == value)
-            || option_num_parse.is_some_and(|signal_value| signal_value == value + OFFSET)
-        {
-            println!("{signal}");
+    signal_value
+        .checked_sub(OFFSET)
+        .filter(|value| *value <= signal_number_upper_bound())
+}
+
+fn print_signal(signal_name_or_value: &str) -> UResult<()> {
+    if let Ok(signal_value) = signal_name_or_value.parse::<usize>() {
+        // GNU kill accepts plain signal numbers, values masked to the low 8 bits,
+        // and exit statuses that encode `128 + signal`.
+        if let Some(signal_value) = normalize_list_signal_value(signal_value) {
+            println!(
+                "{}",
+                signal_list_name_by_value(signal_value).unwrap_or_else(|| signal_value.to_string())
+            );
             return Ok(());
         }
     }
+
+    if let Some(signal_value) = signal_list_value_by_name_or_number(signal_name_or_value) {
+        println!("{signal_value}");
+        return Ok(());
+    }
+
     Err(USimpleError::new(
         1,
         translate!("kill-error-invalid-signal", "signal" => signal_name_or_value.quote()),
@@ -194,8 +207,10 @@ fn print_signal(signal_name_or_value: &str) -> UResult<()> {
 }
 
 fn print_signals() {
-    for signal in ALL_SIGNALS {
-        println!("{signal}");
+    for signal_value in 0..=signal_number_upper_bound() {
+        if let Some(signal_name) = signal_list_name_by_value(signal_value) {
+            println!("{signal_name}");
+        }
     }
 }
 

src/uucore/src/lib/features/signals.rs

@@ -12,6 +12,8 @@
 
 #[cfg(unix)]
 use nix::errno::Errno;
+#[cfg(any(target_os = "linux", target_os = "android"))]
+use nix::libc;
 #[cfg(unix)]
 use nix::sys::signal::{
     SaFlags, SigAction, SigHandler, SigHandler::SigDfl, SigHandler::SigIgn, SigSet, Signal,
@@ -411,6 +413,63 @@ pub fn signal_name_by_value(signal_value: usize) -> Option<&'static str> {
     ALL_SIGNALS.get(signal_value).copied()
 }
 
+#[cfg(any(target_os = "linux", target_os = "android"))]
+fn realtime_signal_bounds() -> Option<(usize, usize)> {
+    let rtmin = libc::SIGRTMIN();
+    let rtmax = libc::SIGRTMAX();
+
+    (0 < rtmin && rtmin <= rtmax).then_some((rtmin as usize, rtmax as usize))
+}
+
+#[cfg(not(any(target_os = "linux", target_os = "android")))]
+fn realtime_signal_bounds() -> Option<(usize, usize)> {
+    None
+}
+
+/// Returns the largest signal number that list-style interfaces should accept.
+pub fn signal_number_upper_bound() -> usize {
+    let base = ALL_SIGNALS.len() - 1;
+
+    realtime_signal_bounds().map_or(base, |(_, rtmax)| rtmax.max(base))
+}
+
+/// Returns the signal name for list-style interfaces.
+pub fn signal_list_name_by_value(signal_value: usize) -> Option<String> {
+    if let Some(signal_name) = signal_name_by_value(signal_value) {
+        return Some(signal_name.to_string());
+    }
+
+    realtime_signal_bounds().and_then(|(rtmin, rtmax)| {
+        if signal_value == rtmin {
+            Some("RTMIN".to_string())
+        } else if signal_value == rtmax {
+            Some("RTMAX".to_string())
+        } else {
+            None
+        }
+    })
+}
+
+/// Returns the signal value for list-style interfaces.
+pub fn signal_list_value_by_name_or_number(spec: &str) -> Option<usize> {
+    let spec_upcase = spec.to_uppercase();
+
+    if let Ok(value) = spec_upcase.parse::<usize>() {
+        return (value <= signal_number_upper_bound()).then_some(value);
+    }
+
+    if let Some(value) = signal_by_name_or_value(&spec_upcase) {
+        return Some(value);
+    }
+
+    let signal_name = spec_upcase.trim_start_matches("SIG");
+    realtime_signal_bounds().and_then(|(rtmin, rtmax)| match signal_name {
+        "RTMIN" => Some(rtmin),
+        "RTMAX" => Some(rtmax),
+        _ => None,
+    })
+}
+
 /// Restores SIGPIPE to default behavior (process terminates on broken pipe).
 #[cfg(unix)]
 pub fn enable_pipe_errors() -> Result<(), Errno> {
@@ -642,3 +701,56 @@ fn name() {
         assert_eq!(signal_name_by_value(value), Some(*signal));
     }
 }
+
+#[test]
+fn list_signal_names_match_static_signal_names() {
+    for (value, signal) in ALL_SIGNALS.iter().enumerate() {
+        assert_eq!(signal_list_name_by_value(value), Some(signal.to_string()));
+    }
+}
+
+#[test]
+fn list_signal_numbers_follow_upper_bound() {
+    assert_eq!(
+        signal_list_value_by_name_or_number(&signal_number_upper_bound().to_string()),
+        Some(signal_number_upper_bound())
+    );
+    assert_eq!(
+        signal_list_value_by_name_or_number(&(signal_number_upper_bound() + 1).to_string()),
+        None
+    );
+}
+
+#[cfg(any(target_os = "linux", target_os = "android"))]
+#[test]
+fn linux_realtime_signal_upper_bound_includes_rtmax() {
+    let (_, rtmax) = realtime_signal_bounds().unwrap();
+    assert!(signal_number_upper_bound() >= rtmax);
+}
+
+#[cfg(any(target_os = "linux", target_os = "android"))]
+#[test]
+fn linux_realtime_signal_names_are_listed() {
+    let (rtmin, rtmax) = realtime_signal_bounds().unwrap();
+
+    assert_eq!(signal_list_name_by_value(rtmin), Some("RTMIN".to_string()));
+    assert_eq!(signal_list_name_by_value(rtmax), Some("RTMAX".to_string()));
+}
+
+#[cfg(any(target_os = "linux", target_os = "android"))]
+#[test]
+fn linux_realtime_signal_names_resolve_to_runtime_values() {
+    let (rtmin, rtmax) = realtime_signal_bounds().unwrap();
+
+    assert_eq!(signal_list_value_by_name_or_number("RTMIN"), Some(rtmin));
+    assert_eq!(signal_list_value_by_name_or_number("RTMAX"), Some(rtmax));
+    assert_eq!(signal_list_value_by_name_or_number("SIGRTMIN"), Some(rtmin));
+    assert_eq!(signal_list_value_by_name_or_number("SIGRTMAX"), Some(rtmax));
+}
+
+#[cfg(any(target_os = "linux", target_os = "android"))]
+#[test]
+fn linux_unnamed_signal_numbers_are_valid_for_lists() {
+    assert_eq!(signal_list_value_by_name_or_number("32"), Some(32));
+    assert_eq!(signal_list_value_by_name_or_number("33"), Some(33));
+}

tests/by-util/test_kill.rs

@@ -2,7 +2,7 @@
 //
 // For the full copyright and license information, please view the LICENSE
 // file that was distributed with this source code.
-// spell-checker:ignore IAMNOTASIGNAL
+// spell-checker:ignore IAMNOTASIGNAL RTMAX RTMIN SIGRTMAX
 use regex::Regex;
 use std::os::unix::process::ExitStatusExt;
 use std::process::{Child, Command};
@@ -67,6 +67,16 @@ fn test_kill_list_all_signals() {
         .stdout_contains("EXIT");
 }
 
+#[cfg(any(target_os = "linux", target_os = "android"))]
+#[test]
+fn test_kill_list_contains_realtime_signals() {
+    new_ucmd!()
+        .arg("-l")
+        .succeeds()
+        .stdout_contains("RTMIN")
+        .stdout_contains("RTMAX");
+}
+
 #[test]
 fn test_kill_list_final_new_line() {
     let re = Regex::new("\\n$").unwrap();
@@ -85,6 +95,16 @@ fn test_kill_list_all_signals_as_table() {
         .stdout_contains("EXIT");
 }
 
+#[cfg(any(target_os = "linux", target_os = "android"))]
+#[test]
+fn test_kill_table_contains_realtime_signals() {
+    new_ucmd!()
+        .arg("-t")
+        .succeeds()
+        .stdout_contains("RTMIN")
+        .stdout_contains("RTMAX");
+}
+
 #[test]
 fn test_kill_table_starts_at_0() {
     new_ucmd!()
@@ -118,6 +138,16 @@ fn test_kill_list_one_signal_from_number() {
         .stdout_only("KILL\n");
 }
 
+#[cfg(any(target_os = "linux", target_os = "android"))]
+#[test]
+fn test_kill_list_rtmax_from_name() {
+    new_ucmd!()
+        .arg("-l")
+        .arg("RTMAX")
+        .succeeds()
+        .stdout_only(format!("{}\n", libc::SIGRTMAX()));
+}
+
 #[test]
 fn test_kill_list_one_signal_from_invalid_number() {
     new_ucmd!()
@@ -385,6 +415,50 @@ fn test_kill_with_list_lower_bits_unrecognized() {
     new_ucmd!().arg("-l").arg("384").fails();
 }
 
+#[cfg(any(target_os = "linux", target_os = "android"))]
+#[test]
+fn test_kill_with_list_unnamed_signal_numbers() {
+    new_ucmd!()
+        .arg("-l")
+        .arg("32")
+        .succeeds()
+        .stdout_only("32\n");
+    new_ucmd!()
+        .arg("-l")
+        .arg("33")
+        .succeeds()
+        .stdout_only("33\n");
+}
+
+#[cfg(any(target_os = "linux", target_os = "android"))]
+#[test]
+fn test_kill_with_list_all_signal_numbers_up_to_last_named_signal() {
+    let last_signal_name = new_ucmd!()
+        .arg("-l")
+        .succeeds()
+        .stdout_str()
+        .lines()
+        .last()
+        .unwrap()
+        .to_string();
+
+    let last_signal_number: usize = new_ucmd!()
+        .arg("-l")
+        .arg("--")
+        .arg(&last_signal_name)
+        .succeeds()
+        .stdout_str()
+        .trim()
+        .parse()
+        .unwrap();
+
+    let args = std::iter::once(String::from("--"))
+        .chain((0..=last_signal_number).map(|signal| signal.to_string()))
+        .collect::<Vec<_>>();
+
+    new_ucmd!().arg("-l").args(&args).succeeds();
+}
+
 #[test]
 fn test_kill_with_signal_and_table() {
     let target = Target::new();