Add handling of interrupting signals to ETUI

Signed-off-by: Dan Luhring <dan.luhring@anchore.com>

internal/ui/etui/ephemeral_tui.go

@@ -23,7 +23,9 @@ import (
 	"context"
 	"fmt"
 	"os"
+	"os/signal"
 	"sync"
+	"syscall"
 
 	"github.com/anchore/syft/internal/logger"
 
@@ -102,6 +104,8 @@ func OutputToEphemeralTUI(workerErrs <-chan error, subscription *partybus.Subscr
 	ctx := context.Background()
 	syftUIHandler := ui.NewHandler()
 
+	signals := interruptingSignals()
+
 eventLoop:
 	for {
 		select {
@@ -154,8 +158,23 @@ eventLoop:
 				log.Errorf("cancelled (%+v)", err)
 			}
 			break eventLoop
+		case <-signals:
+			break eventLoop
 		}
 	}
 
 	return nil
 }
+
+func interruptingSignals() chan os.Signal {
+	c := make(chan os.Signal, 1) // Note: A buffered channel is recommended for this; see https://golang.org/pkg/os/signal/#Notify
+
+	interruptions := []os.Signal{
+		syscall.SIGINT,
+		syscall.SIGTERM,
+	}
+
+	signal.Notify(c, interruptions...)
+
+	return c
+}