timeout: disable timeout if it is set to zero

src/uu/timeout/src/timeout.rs

@@ -214,10 +214,6 @@ fn timeout(
                     }
                 }
                 Ok(None) => {
-                    if kill_after == Duration::new(0, 0) {
-                        // XXX: this may not be right
-                        return 124;
-                    }
                     if verbose {
                         show_error!("sending signal KILL to command '{}'", cmd[0]);
                     }

src/uucore/src/lib/features/process.rs

@@ -93,6 +93,7 @@ pub trait ChildExt {
     fn send_signal(&mut self, signal: usize) -> io::Result<()>;
 
     /// Wait for a process to finish or return after the specified duration.
+    /// A `timeout` of zero disables the timeout.
     fn wait_or_timeout(&mut self, timeout: Duration) -> io::Result<Option<ExitStatus>>;
 }
 
@@ -106,6 +107,11 @@ impl ChildExt for Child {
     }
 
     fn wait_or_timeout(&mut self, timeout: Duration) -> io::Result<Option<ExitStatus>> {
+        if timeout == Duration::from_micros(0) {
+            return self
+                .wait()
+                .map(|status| Some(ExitStatus::from_std_status(status)));
+        }
         // .try_wait() doesn't drop stdin, so we do it manually
         drop(self.stdin.take());
 

tests/by-util/test_timeout.rs

@@ -31,3 +31,17 @@ fn test_verbose() {
             .stderr_only("timeout: sending signal EXIT to command 'sleep'\ntimeout: sending signal KILL to command 'sleep'");
     }
 }
+
+#[test]
+fn test_zero_timeout() {
+    new_ucmd!()
+        .args(&["-v", "0", "sleep", ".1"])
+        .succeeds()
+        .no_stderr()
+        .no_stdout();
+    new_ucmd!()
+        .args(&["-v", "0", "-s0", "-k0", "sleep", ".1"])
+        .succeeds()
+        .no_stderr()
+        .no_stdout();
+}