Fix gaping race condition in ParRun() that was causing an infinite loop

when getting a termination signal. Also add an option to not redefine
the HUP handler, which is needed for the portal_monitor, which uses the
HUP signal to reopen the logfile (from syslogd).

db/emutil.pm.in

@@ -44,6 +44,7 @@ use Carp;
 use Date::Parse;
 use Time::Local;
 use Data::Dumper;
+use POSIX qw(:signal_h);
 
 # Configure variables.
 my $TB          = "@prefix@";
@@ -359,6 +360,7 @@ sub ParRun($$$@)
     my @results  = ();
     my $counter  = 0;
     my $signaled = 0;
+    my $nosighup = 0;
     # We need this below.
     require event;
 
@@ -371,6 +373,8 @@ sub ParRun($$$@)
 	    if (exists($options->{'maxchildren'}));
 	$maxwaittime = $options->{'maxwaittime'}
 	    if (exists($options->{'maxwaittime'}));
+	$nosighup = $options->{'nosighup'}
+	    if (exists($options->{'nosighup'}));
     }
 
     #
@@ -379,20 +383,21 @@ sub ParRun($$$@)
     my $coderef = sub {
 	my ($signame) = @_;
 
-	print STDERR "Caught SIG${signame}! Killing parrun ...";
+	print STDERR "Caught SIG${signame} in $$! Killing parrun ...\n";
 
 	$SIG{TERM} = 'IGNORE';
 	$signaled = 1;
 
 	foreach my $pid (keys(%children)) {
-	    kill('TERM', $pid);
+	    print STDERR "Sending HUP signal to $pid ...\n";
+	    kill('HUP', $pid);
 	}
 	sleep(1);
     };
     local $SIG{QUIT} = $coderef;
     local $SIG{TERM} = $coderef;
-    local $SIG{HUP}  = $coderef;
     local $SIG{INT}  = $coderef;
+    local $SIG{HUP}  = $coderef if (!$nosighup);
 
     #
     # Initialize return.
@@ -401,40 +406,59 @@ sub ParRun($$$@)
 	$results[$i] = -1;
     }
 
-    while (@objects || keys(%children)) {
+    while ((@objects && !$signaled) || keys(%children)) {
 	#
 	# Something to do and still have free slots.
 	#
 	if (@objects && keys(%children) < $maxchildren && !$signaled) {
 	    # Space out the invocation of child processes a little.
 	    sleep(1);
-	    
-	    #
-	    # Run command in a child process, protected by an alarm to
-	    # ensure that whatever happens is not hung up forever in
-	    # some funky state.
-	    #
-	    my $object = shift(@objects);
-	    my $syspid = fork();
 
-	    if ($syspid) {
+	    my $newsigset = POSIX::SigSet->new(SIGQUIT,SIGINT,SIGTERM,SIGHUP);
+	    my $oldsigset = POSIX::SigSet->new;
+	    if (! defined(sigprocmask(SIG_BLOCK, $newsigset, $oldsigset))) {
+		print STDERR "sigprocmask (BLOCK) failed!\n";
+		return -1;
+	    }
+	    if (!$signaled) {
 		#
-		# Just keep track of it, we'll wait for it finish down below
+		# Run command in a child process, protected by an alarm to
+		# ensure that whatever happens is not hung up forever in
+		# some funky state.
 		#
-		$children{$syspid} = [$object, $counter, time()];
-		$counter++;
-	    }
-	    else {
-		$SIG{TERM} = 'DEFAULT';
-		$SIG{QUIT} = 'DEFAULT';
-		$SIG{HUP}  = 'DEFAULT';
-
-		# So randomness is not the same in different children
-		srand();
+		my $object = shift(@objects);
+		my $syspid = fork();
+
+		if ($syspid) {
+		    #
+		    # Just keep track of it, we'll wait for it finish down below
+		    #
+		    $children{$syspid} = [$object, $counter, time()];
+		    $counter++;
+		}
+		else {
+		    $SIG{TERM} = 'DEFAULT';
+		    $SIG{QUIT} = 'DEFAULT';
+		    $SIG{HUP}  = 'DEFAULT';
+		    $SIG{INT}  = 'IGNORE';
+
+		    # Unblock in child after resetting the handlers.
+		    if (! defined(sigprocmask(SIG_SETMASK, $oldsigset))) {
+			print STDERR "sigprocmask (UNBLOCK) failed!\n";
+		    }
+		
+		    # So randomness is not the same in different children
+		    srand();
 		
-		# So we get the event system fork too ...
-		event::EventFork();
-		exit(&$function($object));
+		    # So we get the event system fork too ...
+		    event::EventFork();
+		    exit(&$function($object));
+		}
+	    }
+	    # Unblock after critical section.
+	    if (! defined(sigprocmask(SIG_SETMASK, $oldsigset))) {
+		print STDERR "sigprocmask (UNBLOCK) failed!\n";
+		return -1;
 	    }
 	}
 	elsif ($signaled) {