2 files changed, 75 insertions, 8 deletions
diff --git a/pkg/kconfig/kconfig.go b/pkg/kconfig/kconfig.go
index 021929781..7cb54a1bb 100644
--- a/pkg/kconfig/kconfig.go
+++ b/pkg/kconfig/kconfig.go
@@ -30,13 +30,15 @@ type Menu struct {
 	Elems  []*Menu    // sub-elements for menus
 	Parent *Menu      // parent menu, non-nil for everythign except for mainmenu
 
-	kconf     *KConfig // back-link to the owning KConfig
-	prompts   []prompt
-	defaults  []defaultVal
-	dependsOn expr
-	visibleIf expr
-	deps      map[string]bool
-	depsOnce  sync.Once
+	kconf      *KConfig // back-link to the owning KConfig
+	prompts    []prompt
+	defaults   []defaultVal
+	dependsOn  expr
+	visibleIf  expr
+	deps       map[string]bool
+	depsOnce   sync.Once
+	selects    []string
+	selectedBy []string // filled in in setSelectedBy()
 }
 
 type prompt struct {
@@ -144,6 +146,7 @@ func ParseData(target *targets.Target, data []byte, file string) (*KConfig, erro
 		Configs: make(map[string]*Menu),
 	}
 	kconf.walk(root, nil, nil)
+	kconf.setSelectedBy()
 	return kconf, nil
 }
 
@@ -159,6 +162,37 @@ func (kconf *KConfig) walk(m *Menu, dependsOn, visibleIf expr) {
 	}
 }
 
+// NOTE: the function is ignoring the "if" part of select/imply.
+func (kconf *KConfig) setSelectedBy() {
+	for name, cfg := range kconf.Configs {
+		for _, selectedName := range cfg.selects {
+			selected := kconf.Configs[selectedName]
+			if selected == nil {
+				continue
+			}
+			selected.selectedBy = append(selected.selectedBy, name)
+		}
+	}
+}
+
+// NOTE: the function is ignoring the "if" part of select/imply.
+func (kconf *KConfig) SelectedBy(name string) map[string]bool {
+	ret := map[string]bool{}
+	toVisit := []string{name}
+	for len(toVisit) > 0 {
+		next := kconf.Configs[toVisit[len(toVisit)-1]]
+		toVisit = toVisit[:len(toVisit)-1]
+		if next == nil {
+			continue
+		}
+		for _, selectedBy := range next.selectedBy {
+			ret[selectedBy] = true
+			toVisit = append(toVisit, selectedBy)
+		}
+	}
+	return ret
+}
+
 func (kp *kconfigParser) parseFile() {
 	for kp.nextLine() {
 		kp.parseLine()
@@ -293,7 +327,8 @@ func (kp *kconfigParser) parseProperty(prop string) {
 		kp.MustConsume("if")
 		cur.visibleIf = exprAnd(cur.visibleIf, kp.parseExpr())
 	case "select", "imply":
-		_ = kp.Ident()
+		name := kp.Ident()
+		cur.selects = append(cur.selects, name)
 		if kp.TryConsume("if") {
 			_ = kp.parseExpr()
 		}
diff --git a/pkg/kconfig/kconfig_test.go b/pkg/kconfig/kconfig_test.go
index 994f1856f..44eda3168 100644
--- a/pkg/kconfig/kconfig_test.go
+++ b/pkg/kconfig/kconfig_test.go
@@ -8,6 +8,7 @@ import (
 	"testing"
 
 	"github.com/google/syzkaller/sys/targets"
+	"github.com/stretchr/testify/assert"
 )
 
 func TestParseKConfig(t *testing.T) {
@@ -35,6 +36,37 @@ config FOO
 	}
 }
 
+func TestSelectedby(t *testing.T) {
+	configData := `
+mainmenu "test"
+
+config FEATURE_A
+    bool "Feature A"
+    select FEATURE_B
+
+config FEATURE_B
+    bool "Feature B"
+    select FEATURE_C
+
+config FEATURE_C
+    bool "Feature C"
+
+`
+	target := targets.Get("linux", "amd64")
+	kconf, err := ParseData(target, []byte(configData), "Kconfig")
+	if err != nil {
+		t.Fatal(err)
+	}
+	assert.Empty(t, kconf.SelectedBy("FEATURE_A"))
+	assert.Equal(t, map[string]bool{
+		"FEATURE_A": true,
+	}, kconf.SelectedBy("FEATURE_B"))
+	assert.Equal(t, map[string]bool{
+		"FEATURE_A": true,
+		"FEATURE_B": true,
+	}, kconf.SelectedBy("FEATURE_C"))
+}
+
 func TestFuzzParseKConfig(t *testing.T) {
 	for _, data := range []string{
 		``,