btf: fix marshaling of typeTag and declTag

Marshaling of typeTag and declTag is currently broken. This is because we rely on marshaling vmlinux BTF for test coverage, which doesn't contain tags since we don't compile with clang. Signed-off-by: Lorenz Bauer <[email protected]>
shane965 · Mar 3, 2023 · 13c9b3b · 13c9b3b
1 parent b673899
commit 13c9b3b
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Showing 2 changed files with 27 additions and 0 deletions.
diff --git a/btf/marshal.go b/btf/marshal.go
@@ -319,10 +319,13 @@ func (e *encoder) deflateType(typ Type) (err error) {
 
 	case *declTag:
 		raw.SetKind(kindDeclTag)
+		raw.SetType(e.id(v.Type))
 		raw.data = &btfDeclTag{uint32(v.Index)}
+		raw.NameOff, err = e.strings.Add(v.Value)
 
 	case *typeTag:
 		raw.SetKind(kindTypeTag)
+		raw.SetType(e.id(v.Type))
 		raw.NameOff, err = e.strings.Add(v.Value)
 
 	default:

diff --git a/btf/types_test.go b/btf/types_test.go
@@ -1,10 +1,13 @@
 package btf
 
 import (
+	"bytes"
 	"fmt"
 	"reflect"
 	"testing"
 
+	"github.com/cilium/ebpf/internal"
+
 	qt "github.com/frankban/quicktest"
 	"github.com/google/go-cmp/cmp"
 )
@@ -196,6 +199,27 @@ func TestType(t *testing.T) {
 	}
 }
 
+func TestTagMarshaling(t *testing.T) {
+	for _, typ := range []Type{
+		&declTag{&Struct{Members: []Member{}}, "foo", -1},
+		&typeTag{&Int{}, "foo"},
+	} {
+		t.Run(fmt.Sprint(typ), func(t *testing.T) {
+			var buf bytes.Buffer
+			err := marshalTypes(&buf, []Type{&Void{}, typ}, nil, nil)
+			qt.Assert(t, err, qt.IsNil)
+
+			s, err := loadRawSpec(bytes.NewReader(buf.Bytes()), internal.NativeEndian, nil, nil)
+			qt.Assert(t, err, qt.IsNil)
+
+			have, err := s.TypeByID(1)
+			qt.Assert(t, err, qt.IsNil)
+
+			qt.Assert(t, have, qt.DeepEquals, typ)
+		})
+	}
+}
+
 func countChildren(t *testing.T, typ reflect.Type) int {
 	if typ.Kind() != reflect.Pointer {
 		t.Fatal("Expected pointer, got", typ.Kind())