test.pl: Simpler method to cancel watchdog timers

The added END block can simply call watchdog(0), which already has the
knowledge to be able to cancel whichever watachdog method is used.

Spotted by Tony Cook

A comment is added as to why no cancellation is needed of a watchdog
implemented by alarm().

Even though a test file should clear every timer before exit, this makes
sure it happens.

Author: khwilliamson

t/test.pl

@@ -1838,6 +1838,10 @@ sub warning_like {
 { # Closure
     my $watchdog_process;
     my $watchdog_thread;
+    my $watchdog_alarm;
+
+    # Add END block to terminate and clean up any watchdog
+    END { watchdog(0); };
 
 sub watchdog ($;$)
 {
@@ -1846,18 +1850,21 @@ ($;$)
     # If cancelling, use the state variables to know which method was used to
     # create the watchdog.
     if ($timeout == 0) {
+
+        # Is a no-op if no watchdog is currently set
         if ($watchdog_thread) {
             $watchdog_thread->kill('KILL');
-            undef $watchdog_thread;
         }
         elsif ($watchdog_process) {
             kill('KILL', $watchdog_process);
-            undef $watchdog_process;
         }
-        else {
+        elsif ($watchdog_alarm) {
             alarm(0);
         }
 
+        undef $watchdog_thread;
+        undef $watchdog_process;
+        undef $watchdog_alarm;
         return;
     }
 
@@ -1956,24 +1963,14 @@ ($;$)
                 goto WATCHDOG_VIA_ALARM;
             }
 
-            # Add END block to parent to terminate and clean up watchdog
-            # process
-            eval("END { local \$! = 0; local \$? = 0;
-                        wait() if kill('KILL', $watchdog_process); };");
             return;
         }
 
         # Try using fork() to generate a watchdog process
         undef $watchdog_process;
         eval { $watchdog_process = fork() };
         if (defined($watchdog_process)) {
-            if ($watchdog_process) {   # Parent process
-                # Add END block to parent to terminate and clean up watchdog
-                # process
-                eval "END { local \$! = 0; local \$? = 0;
-                            wait() if kill('KILL', $watchdog_process); };";
-                return;
-            }
+            return if $watchdog_process;  # Parent process
 
             ### Watchdog process code
 
@@ -2061,6 +2058,8 @@ ($;$)
             my $sig = $is_vms ? 'TERM' : 'KILL';
             kill($sig, $pid_to_kill);
         };
+
+        $watchdog_alarm = 1;
     }
 }
 } # End closure