Ensure shutdown handler access is syncronized

There was a potential race where two handlers could be added at
the same time. Go Maps are not thread-safe, so that could do
unpleasant things. Add a mutex to keep things safe.

Also, swap the order or Register and Start for the handlers in
Libpod runtime created. As written, there was a small gap between
Start and Register where SIGTERM/SIGINT would be completely
ignored, instead of stopping Podman. Swapping the two closes this
gap.

Signed-off-by: Matthew Heon <mheon@redhat.com>

1 files changed, 7 insertions, 7 deletions

diff --git a/libpod/runtime.go b/libpod/runtime.go
index 34c737a67..0dc220b52 100644
--- a/libpod/runtime.go
+++ b/libpod/runtime.go
@@ -180,6 +180,13 @@ func newRuntimeFromConfig(ctx context.Context, conf *config.Config, options ...R
 		}
 	}
 
+	if err := shutdown.Register("libpod", func(sig os.Signal) error {
+		os.Exit(1)
+		return nil
+	}); err != nil && errors.Cause(err) != shutdown.ErrHandlerExists {
+		logrus.Errorf("Error registering shutdown handler for libpod: %v", err)
+	}
+
 	if err := shutdown.Start(); err != nil {
 		return nil, errors.Wrapf(err, "error starting shutdown signal handler")
 	}
@@ -188,13 +195,6 @@ func newRuntimeFromConfig(ctx context.Context, conf *config.Config, options ...R
 		return nil, err
 	}
 
-	if err := shutdown.Register("libpod", func(sig os.Signal) error {
-		os.Exit(1)
-		return nil
-	}); err != nil && errors.Cause(err) != shutdown.ErrHandlerExists {
-		logrus.Errorf("Error registering shutdown handler for libpod: %v", err)
-	}
-
 	return runtime, nil
 }