uucore: support realtime signals (RTMIN/RTMAX) in signal_by_name_or_value

`signal_by_name_or_value()` only looked up signals from the static
ALL_SIGNALS array, which doesn't include realtime signals. This caused
`timeout -s RTMAX`, `kill -s RTMIN`, and `env --default-signal=RTMAX`
to reject valid signal names.

Extend the function to fall back to realtime_signal_bounds() for both
name lookups and numeric values in the realtime range, matching the
behavior already present in signal_list_value_by_name_or_number().

Also fix timeout's report_if_verbose() to use signal_list_name_by_value
instead of signal_name_by_value, so verbose output doesn't panic for
realtime signal numbers.

Fixes GNU test: tests/env/env-signal-handler.sh

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

.vscode/cspell.dictionaries/workspace.wordlist.txt

@@ -185,9 +185,13 @@ LINESIZE
 NAMESIZE
 RTLD_NEXT
     RTLD
+RTMAX
+RTMIN
 SIGABRT
 SIGINT
 SIGKILL
+SIGRTMAX
+SIGRTMIN
 SIGSTOP
 SIGTERM
 SYS_fdatasync

src/uu/timeout/src/timeout.rs

@@ -22,7 +22,7 @@ use uucore::translate;
 
 use uucore::{
     format_usage,
-    signals::{signal_by_name_or_value, signal_name_by_value},
+    signals::{signal_by_name_or_value, signal_list_name_by_value},
 };
 
 use nix::sys::signal::{SigHandler, Signal, kill};
@@ -227,7 +227,7 @@ fn report_if_verbose(signal: usize, cmd: &str, verbose: bool) {
         let s = if signal == 0 {
             "0".to_string()
         } else {
-            signal_name_by_value(signal).unwrap().to_string()
+            signal_list_name_by_value(signal).unwrap()
         };
         let mut stderr = std::io::stderr();
         let _ = writeln!(

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

@@ -396,11 +396,24 @@ pub static ALL_SIGNALS: [&str; 32] = [
 pub fn signal_by_name_or_value(signal_name_or_value: &str) -> Option<usize> {
     let signal_name_upcase = signal_name_or_value.to_uppercase();
     if let Ok(value) = signal_name_upcase.parse() {
-        return if is_signal(value) { Some(value) } else { None };
+        if is_signal(value) {
+            return Some(value);
+        }
+        return realtime_signal_bounds()
+            .filter(|&(rtmin, rtmax)| value >= rtmin && value <= rtmax)
+            .map(|_| value);
     }
     let signal_name = signal_name_upcase.trim_start_matches("SIG");
 
-    ALL_SIGNALS.iter().position(|&s| s == signal_name)
+    if let Some(pos) = ALL_SIGNALS.iter().position(|&s| s == signal_name) {
+        return Some(pos);
+    }
+
+    realtime_signal_bounds().and_then(|(rtmin, rtmax)| match signal_name {
+        "RTMIN" => Some(rtmin),
+        "RTMAX" => Some(rtmax),
+        _ => None,
+    })
 }
 
 /// Returns true if the given number is a valid signal number.
@@ -754,3 +767,19 @@ 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));
 }
+
+#[cfg(any(target_os = "linux", target_os = "android"))]
+#[test]
+fn linux_realtime_signals_resolve_by_name_or_value() {
+    let (rtmin, rtmax) = realtime_signal_bounds().unwrap();
+
+    // By name
+    assert_eq!(signal_by_name_or_value("RTMIN"), Some(rtmin));
+    assert_eq!(signal_by_name_or_value("RTMAX"), Some(rtmax));
+    assert_eq!(signal_by_name_or_value("SIGRTMIN"), Some(rtmin));
+    assert_eq!(signal_by_name_or_value("SIGRTMAX"), Some(rtmax));
+
+    // By numeric value
+    assert_eq!(signal_by_name_or_value(&rtmin.to_string()), Some(rtmin));
+    assert_eq!(signal_by_name_or_value(&rtmax.to_string()), Some(rtmax));
+}

tests/by-util/test_timeout.rs

@@ -286,3 +286,21 @@ fn test_foreground_signal0_kill_after() {
         .args(&["--foreground", "-s0", "-k.1", ".1", "sleep", "10"])
         .fails_with_code(137);
 }
+
+#[test]
+#[cfg(any(target_os = "linux", target_os = "android"))]
+fn test_realtime_signal_names() {
+    // timeout should accept RTMIN and RTMAX as valid signal names
+    new_ucmd!()
+        .args(&["-v", "-s", "RTMAX", ".1", "sleep", "1"])
+        .fails()
+        .stderr_contains("sending signal RTMAX to command");
+    new_ucmd!()
+        .args(&["-v", "-s", "RTMIN", ".1", "sleep", "1"])
+        .fails()
+        .stderr_contains("sending signal RTMIN to command");
+    new_ucmd!()
+        .args(&["-v", "-s", "SIGRTMAX", ".1", "sleep", "1"])
+        .fails()
+        .stderr_contains("sending signal RTMAX to command");
+}