Fix `system service` panic from early hangup in events

We weren't actually halting the goroutine that sent events, so it
would continue sending even when the channel closed (the most
notable cause being early hangup - e.g. Control-c on a curl
session). Use a context to cancel the events goroutine and stop
sending events.

Fixes #6805

Signed-off-by: Matthew Heon <matthew.heon@pm.me>

5 files changed, 12 insertions, 6 deletions

diff --git a/pkg/api/handlers/compat/events.go b/pkg/api/handlers/compat/events.go
index 577ddd0a1..fca50c321 100644
--- a/pkg/api/handlers/compat/events.go
+++ b/pkg/api/handlers/compat/events.go
@@ -1,6 +1,7 @@
 package compat
 
 import (
+	"context"
 	"fmt"
 	"net/http"
 
@@ -45,13 +46,15 @@ func GetEvents(w http.ResponseWriter, r *http.Request) {
 		fromStart = true
 	}
 
+	eventCtx, eventCancel := context.WithCancel(r.Context())
 	eventChannel := make(chan *events.Event)
 	go func() {
 		readOpts := events.ReadOptions{FromStart: fromStart, Stream: query.Stream, Filters: libpodFilters, EventChannel: eventChannel, Since: query.Since, Until: query.Until}
-		eventsError = runtime.Events(readOpts)
+		eventsError = runtime.Events(eventCtx, readOpts)
 	}()
 	if eventsError != nil {
 		utils.InternalServerError(w, eventsError)
+		eventCancel()
 		close(eventChannel)
 		return
 	}
@@ -59,6 +62,7 @@ func GetEvents(w http.ResponseWriter, r *http.Request) {
 	// If client disappears we need to stop listening for events
 	go func(done <-chan struct{}) {
 		<-done
+		eventCancel()
 		if _, ok := <-eventChannel; ok {
 			close(eventChannel)
 		}
diff --git a/pkg/domain/infra/abi/containers.go b/pkg/domain/infra/abi/containers.go
index 22de28a1c..f31ea3945 100644
--- a/pkg/domain/infra/abi/containers.go
+++ b/pkg/domain/infra/abi/containers.go
@@ -741,7 +741,7 @@ func (ic *ContainerEngine) ContainerStart(ctx context.Context, namesOrIds []stri
 			if ecode, err := ctr.Wait(); err != nil {
 				if errors.Cause(err) == define.ErrNoSuchCtr {
 					// Check events
-					event, err := ic.Libpod.GetLastContainerEvent(ctr.ID(), events.Exited)
+					event, err := ic.Libpod.GetLastContainerEvent(ctx, ctr.ID(), events.Exited)
 					if err != nil {
 						logrus.Errorf("Cannot get exit code: %v", err)
 						exitCode = define.ExecErrorCodeNotFound
@@ -871,7 +871,7 @@ func (ic *ContainerEngine) ContainerRun(ctx context.Context, opts entities.Conta
 	if ecode, err := ctr.Wait(); err != nil {
 		if errors.Cause(err) == define.ErrNoSuchCtr {
 			// Check events
-			event, err := ic.Libpod.GetLastContainerEvent(ctr.ID(), events.Exited)
+			event, err := ic.Libpod.GetLastContainerEvent(ctx, ctr.ID(), events.Exited)
 			if err != nil {
 				logrus.Errorf("Cannot get exit code: %v", err)
 				report.ExitCode = define.ExecErrorCodeNotFound
diff --git a/pkg/domain/infra/abi/events.go b/pkg/domain/infra/abi/events.go
index 7ec9db369..c999faeee 100644
--- a/pkg/domain/infra/abi/events.go
+++ b/pkg/domain/infra/abi/events.go
@@ -9,5 +9,5 @@ import (
 
 func (ic *ContainerEngine) Events(ctx context.Context, opts entities.EventsOptions) error {
 	readOpts := events.ReadOptions{FromStart: opts.FromStart, Stream: opts.Stream, Filters: opts.Filter, EventChannel: opts.EventChan, Since: opts.Since, Until: opts.Until}
-	return ic.Libpod.Events(readOpts)
+	return ic.Libpod.Events(ctx, readOpts)
 }
diff --git a/pkg/varlinkapi/attach.go b/pkg/varlinkapi/attach.go
index db977ee5c..2a54d63b5 100644
--- a/pkg/varlinkapi/attach.go
+++ b/pkg/varlinkapi/attach.go
@@ -4,6 +4,7 @@ package varlinkapi
 
 import (
 	"bufio"
+	"context"
 	"io"
 
 	"github.com/containers/libpod/libpod"
@@ -89,7 +90,7 @@ func (i *VarlinkAPI) Attach(call iopodman.VarlinkCall, name string, detachKeys s
 		if ecode, err := ctr.Wait(); err != nil {
 			if errors.Cause(err) == define.ErrNoSuchCtr {
 				// Check events
-				event, err := i.Runtime.GetLastContainerEvent(ctr.ID(), events.Exited)
+				event, err := i.Runtime.GetLastContainerEvent(context.Background(), ctr.ID(), events.Exited)
 				if err != nil {
 					logrus.Errorf("Cannot get exit code: %v", err)
 					exitCode = define.ExecErrorCodeNotFound
diff --git a/pkg/varlinkapi/events.go b/pkg/varlinkapi/events.go
index 33938f08b..471afb7a3 100644
--- a/pkg/varlinkapi/events.go
+++ b/pkg/varlinkapi/events.go
@@ -3,6 +3,7 @@
 package varlinkapi
 
 import (
+	"context"
 	"time"
 
 	"github.com/containers/libpod/libpod/events"
@@ -27,7 +28,7 @@ func (i *VarlinkAPI) GetEvents(call iopodman.VarlinkCall, filter []string, since
 	eventChannel := make(chan *events.Event)
 	go func() {
 		readOpts := events.ReadOptions{FromStart: fromStart, Stream: stream, Filters: filter, EventChannel: eventChannel}
-		eventsError = i.Runtime.Events(readOpts)
+		eventsError = i.Runtime.Events(context.Background(), readOpts)
 	}()
 	if eventsError != nil {
 		return call.ReplyErrorOccurred(eventsError.Error())