vmon: monitor vmon's PID when reaper and executor

If vmon ran a command as its child and was told to be the reaper,
we probably want to see any inherited orphans vmon becomes
responsible for reaping in the graph.

The simplest robust way to achieve this is to monitor vmon's PID
as the root instead of the pid of the command being executed.

There's an argument to be made that this is how it should always
be done when executing a command, but for now I'm only going to
do it when being the reaper.  I think there's also an argument to
be made that becoming a subreaper should also be the default when
executing a command.

1 files changed, 17 insertions, 4 deletions

diff --git a/src/vmon.c b/src/vmon.c
index 347d5d3..927323b 100644
--- a/src/vmon.c
+++ b/src/vmon.c
@@ -698,10 +698,23 @@ static vmon_t * vmon_startup(int argc, const char * const *argv)
 			goto _err_win;
 	}
 
-	vmon->chart = vwm_chart_create(vmon->charts, vmon->pid ? : 1, vmon->width, vmon->height, vmon->name);
-	if (!vmon->chart) {
-		VWM_ERROR("unable to create chart");
-		goto _err_win;
+	{
+		pid_t	root_pid = 1;
+
+		if (vmon->pid)
+			root_pid = vmon->pid;
+
+		/* If vmon is executing the command and being the reaper, make vmon itself the monitored root.
+		 * This way we get to see any orphans.
+		 */
+		if (vmon->execv && vmon->reaper)
+			root_pid = getpid();
+
+		vmon->chart = vwm_chart_create(vmon->charts, root_pid, vmon->width, vmon->height, vmon->name);
+		if (!vmon->chart) {
+			VWM_ERROR("unable to create chart");
+			goto _err_win;
+		}
 	}
 
 	if (vmon->mem_locked) {