pkg/rpcserver: exit on connection loop abortion

For local rpcserver runs, we do not reboot the executor in case of
errors. Moreover, if the error did not lead to the executor process
exit, we may never detect that something went wrong.

Return an error channel from CreateInstance() to be able to act on
connection loop errors.

Explicitly register the instance during local executions and exit from
RunLocal() in case of connection problems.

3 files changed, 20 insertions, 8 deletions

diff --git a/pkg/rpcserver/local.go b/pkg/rpcserver/local.go
index 1886703e9..1420af606 100644
--- a/pkg/rpcserver/local.go
+++ b/pkg/rpcserver/local.go
@@ -42,7 +42,6 @@ func RunLocal(cfg *LocalConfig) error {
 	cfg.UseCoverEdges = true
 	cfg.FilterSignal = true
 	cfg.RPC = ":0"
-	cfg.VMLess = true
 	cfg.PrintMachineCheck = log.V(1)
 	ctx := &local{
 		cfg:       cfg,
@@ -58,8 +57,12 @@ func RunLocal(cfg *LocalConfig) error {
 	// for the race detector b/c it does not understand the synchronization via TCP socket connect/accept.
 	close(ctx.setupDone)
 
+	name := "local"
+	connErr := serv.CreateInstance(name, nil, nil)
+	defer serv.ShutdownInstance(name, true)
+
 	bin := cfg.Executor
-	args := []string{"runner", "local", "localhost", fmt.Sprint(serv.Port)}
+	args := []string{"runner", name, "localhost", fmt.Sprint(serv.Port)}
 	if cfg.GDB {
 		bin = "gdb"
 		args = append([]string{
@@ -91,6 +94,7 @@ func RunLocal(cfg *LocalConfig) error {
 	select {
 	case <-shutdown:
 	case <-cfg.Context.Done():
+	case <-connErr:
 	case err := <-res:
 		cmdErr = fmt.Errorf("executor process exited: %w", err)
 	}
diff --git a/pkg/rpcserver/rpcserver.go b/pkg/rpcserver/rpcserver.go
index 85d4a2bd7..57abafdc9 100644
--- a/pkg/rpcserver/rpcserver.go
+++ b/pkg/rpcserver/rpcserver.go
@@ -212,6 +212,12 @@ func (serv *Server) handleConn(conn *flatrpc.Conn) {
 		return
 	}
 
+	err = serv.handleRunnerConn(runner, conn)
+	log.Logf(2, "runner %v: %v", name, err)
+	runner.resultCh <- err
+}
+
+func (serv *Server) handleRunnerConn(runner *Runner, conn *flatrpc.Conn) error {
 	opts := &handshakeConfig{
 		VMLess:   serv.cfg.VMLess,
 		Files:    serv.checker.RequiredFiles(),
@@ -227,21 +233,20 @@ func (serv *Server) handleConn(conn *flatrpc.Conn) {
 		opts.Features = serv.cfg.Features
 	}
 
-	err = runner.Handshake(conn, opts)
+	err := runner.Handshake(conn, opts)
 	if err != nil {
 		log.Logf(1, "%v", err)
-		return
+		return err
 	}
 
 	if serv.triagedCorpus.Load() {
 		if err := runner.SendCorpusTriaged(); err != nil {
 			log.Logf(2, "%v", err)
-			return
+			return err
 		}
 	}
 
-	err = serv.connectionLoop(runner)
-	log.Logf(2, "runner %v: %v", name, err)
+	return serv.connectionLoop(runner)
 }
 
 func (serv *Server) handleMachineInfo(infoReq *flatrpc.InfoRequestRawT) (handshakeResult, error) {
@@ -393,7 +398,7 @@ func (serv *Server) printMachineCheck(checkFilesInfo []*flatrpc.FileInfo, enable
 	log.Logf(0, "machine check:\n%s", buf.Bytes())
 }
 
-func (serv *Server) CreateInstance(name string, injectExec chan<- bool, updInfo dispatcher.UpdateInfo) {
+func (serv *Server) CreateInstance(name string, injectExec chan<- bool, updInfo dispatcher.UpdateInfo) chan error {
 	runner := &Runner{
 		source:        serv.execSource,
 		cover:         serv.cfg.Cover,
@@ -411,6 +416,7 @@ func (serv *Server) CreateInstance(name string, injectExec chan<- bool, updInfo
 		stats:         serv.runnerStats,
 		procs:         serv.cfg.Procs,
 		updInfo:       updInfo,
+		resultCh:      make(chan error, 1),
 	}
 	serv.mu.Lock()
 	defer serv.mu.Unlock()
@@ -418,6 +424,7 @@ func (serv *Server) CreateInstance(name string, injectExec chan<- bool, updInfo
 		panic(fmt.Sprintf("duplicate instance %s", name))
 	}
 	serv.runners[name] = runner
+	return runner.resultCh
 }
 
 // stopInstance prevents further request exchange requests.
diff --git a/pkg/rpcserver/runner.go b/pkg/rpcserver/runner.go
index ec4ad2076..691a5b5d5 100644
--- a/pkg/rpcserver/runner.go
+++ b/pkg/rpcserver/runner.go
@@ -44,6 +44,7 @@ type Runner struct {
 	lastExec      *LastExecuting
 	rnd           *rand.Rand
 	updInfo       dispatcher.UpdateInfo
+	resultCh      chan error
 
 	// The mutex protects all the fields below.
 	mu          sync.Mutex