From 3ffb6a61130298cd27636df2b64a53e2161cdced Mon Sep 17 00:00:00 2001
From: Brian Goff <cpuguy83@gmail.com>
Date: Wed, 19 Jan 2022 00:23:52 +0000
Subject: [PATCH] shimv2: handle sigint/sigterm

This causes sigint/sigterm to trigger a shutdown of the shim.
It is needed because otherwise the v2 shim hangs system shutdown.

Signed-off-by: Brian Goff <cpuguy83@gmail.com>
---
 runtime/v2/shim/shim.go         | 10 ++++++----
 runtime/v2/shim/shim_unix.go    | 20 +++++++++++++++++++-
 runtime/v2/shim/shim_windows.go |  5 ++++-
 3 files changed, 29 insertions(+), 6 deletions(-)

diff --git a/runtime/v2/shim/shim.go b/runtime/v2/shim/shim.go
index 289b489d648..59e522cede4 100644
--- a/runtime/v2/shim/shim.go
+++ b/runtime/v2/shim/shim.go
@@ -305,7 +305,7 @@ func run(ctx context.Context, manager Manager, initFunc Init, name string, confi
 			"pid":       os.Getpid(),
 			"namespace": namespaceFlag,
 		})
-		go handleSignals(ctx, logger, signals)
+		go reap(ctx, logger, signals)
 		ss, err := manager.Stop(ctx, id)
 		if err != nil {
 			return err
@@ -428,7 +428,7 @@ func run(ctx context.Context, manager Manager, initFunc Init, name string, confi
 		}
 	}
 
-	if err := serve(ctx, server, signals); err != nil {
+	if err := serve(ctx, server, signals, sd.Shutdown); err != nil {
 		if err != shutdown.ErrShutdown {
 			return err
 		}
@@ -450,7 +450,7 @@ func run(ctx context.Context, manager Manager, initFunc Init, name string, confi
 
 // serve serves the ttrpc API over a unix socket in the current working directory
 // and blocks until the context is canceled
-func serve(ctx context.Context, server *ttrpc.Server, signals chan os.Signal) error {
+func serve(ctx context.Context, server *ttrpc.Server, signals chan os.Signal, shutdown func()) error {
 	dump := make(chan os.Signal, 32)
 	setupDumpStacks(dump)
 
@@ -480,7 +480,9 @@ func serve(ctx context.Context, server *ttrpc.Server, signals chan os.Signal) er
 			dumpStacks(logger)
 		}
 	}()
-	return handleSignals(ctx, logger, signals)
+
+	go handleExitSignals(ctx, logger, shutdown)
+	return reap(ctx, logger, signals)
 }
 
 func dumpStacks(logger *logrus.Entry) {
diff --git a/runtime/v2/shim/shim_unix.go b/runtime/v2/shim/shim_unix.go
index 0701fdc6f64..e2dab0931ea 100644
--- a/runtime/v2/shim/shim_unix.go
+++ b/runtime/v2/shim/shim_unix.go
@@ -71,7 +71,7 @@ func serveListener(path string) (net.Listener, error) {
 	return l, nil
 }
 
-func handleSignals(ctx context.Context, logger *logrus.Entry, signals chan os.Signal) error {
+func reap(ctx context.Context, logger *logrus.Entry, signals chan os.Signal) error {
 	logger.Info("starting signal loop")
 
 	for {
@@ -79,6 +79,8 @@ func handleSignals(ctx context.Context, logger *logrus.Entry, signals chan os.Si
 		case <-ctx.Done():
 			return ctx.Err()
 		case s := <-signals:
+			// Exit signals are handled separately from this loop
+			// They get registered with this channel so that we can ignore such signals for short-running actions (e.g. `delete`)
 			switch s {
 			case unix.SIGCHLD:
 				if err := reaper.Reap(); err != nil {
@@ -90,6 +92,22 @@ func handleSignals(ctx context.Context, logger *logrus.Entry, signals chan os.Si
 	}
 }
 
+func handleExitSignals(ctx context.Context, logger *logrus.Entry, cancel context.CancelFunc) {
+	ch := make(chan os.Signal, 32)
+	signal.Notify(ch, syscall.SIGINT, syscall.SIGTERM)
+
+	for {
+		select {
+		case s := <-ch:
+			logger.WithField("signal", s).Debugf("Caught exit signal")
+			cancel()
+			return
+		case <-ctx.Done():
+			return
+		}
+	}
+}
+
 func openLog(ctx context.Context, _ string) (io.Writer, error) {
 	return fifo.OpenFifoDup2(ctx, "log", unix.O_WRONLY, 0700, int(os.Stderr.Fd()))
 }
diff --git a/runtime/v2/shim/shim_windows.go b/runtime/v2/shim/shim_windows.go
index 4eef8c9ffec..4b098ab1630 100644
--- a/runtime/v2/shim/shim_windows.go
+++ b/runtime/v2/shim/shim_windows.go
@@ -46,10 +46,13 @@ func serveListener(path string) (net.Listener, error) {
 	return nil, errors.New("not supported")
 }
 
-func handleSignals(ctx context.Context, logger *logrus.Entry, signals chan os.Signal) error {
+func reap(ctx context.Context, logger *logrus.Entry, signals chan os.Signal) error {
 	return errors.New("not supported")
 }
 
+func handleExitSignals(ctx context.Context, logger *logrus.Entry, cancel context.CancelFunc) {
+}
+
 func openLog(ctx context.Context, _ string) (io.Writer, error) {
 	return nil, errors.New("not supported")
 }