1 files changed, 319 insertions, 0 deletions
diff --git a/vendor/github.com/cilium/ebpf/btf/format.go b/vendor/github.com/cilium/ebpf/btf/format.go
new file mode 100644
index 000000000..e7688a2a6
--- /dev/null
+++ b/vendor/github.com/cilium/ebpf/btf/format.go
@@ -0,0 +1,319 @@
+package btf
+
+import (
+	"errors"
+	"fmt"
+	"strings"
+)
+
+var errNestedTooDeep = errors.New("nested too deep")
+
+// GoFormatter converts a Type to Go syntax.
+//
+// A zero GoFormatter is valid to use.
+type GoFormatter struct {
+	w strings.Builder
+
+	// Types present in this map are referred to using the given name if they
+	// are encountered when outputting another type.
+	Names map[Type]string
+
+	// Identifier is called for each field of struct-like types. By default the
+	// field name is used as is.
+	Identifier func(string) string
+
+	// EnumIdentifier is called for each element of an enum. By default the
+	// name of the enum type is concatenated with Identifier(element).
+	EnumIdentifier func(name, element string) string
+}
+
+// TypeDeclaration generates a Go type declaration for a BTF type.
+func (gf *GoFormatter) TypeDeclaration(name string, typ Type) (string, error) {
+	gf.w.Reset()
+	if err := gf.writeTypeDecl(name, typ); err != nil {
+		return "", err
+	}
+	return gf.w.String(), nil
+}
+
+func (gf *GoFormatter) identifier(s string) string {
+	if gf.Identifier != nil {
+		return gf.Identifier(s)
+	}
+
+	return s
+}
+
+func (gf *GoFormatter) enumIdentifier(name, element string) string {
+	if gf.EnumIdentifier != nil {
+		return gf.EnumIdentifier(name, element)
+	}
+
+	return name + gf.identifier(element)
+}
+
+// writeTypeDecl outputs a declaration of the given type.
+//
+// It encodes https://golang.org/ref/spec#Type_declarations:
+//
+//     type foo struct { bar uint32; }
+//     type bar int32
+func (gf *GoFormatter) writeTypeDecl(name string, typ Type) error {
+	if name == "" {
+		return fmt.Errorf("need a name for type %s", typ)
+	}
+
+	switch v := skipQualifiers(typ).(type) {
+	case *Enum:
+		fmt.Fprintf(&gf.w, "type %s ", name)
+		switch v.Size {
+		case 1:
+			gf.w.WriteString("int8")
+		case 2:
+			gf.w.WriteString("int16")
+		case 4:
+			gf.w.WriteString("int32")
+		case 8:
+			gf.w.WriteString("int64")
+		default:
+			return fmt.Errorf("%s: invalid enum size %d", typ, v.Size)
+		}
+
+		if len(v.Values) == 0 {
+			return nil
+		}
+
+		gf.w.WriteString("; const ( ")
+		for _, ev := range v.Values {
+			id := gf.enumIdentifier(name, ev.Name)
+			fmt.Fprintf(&gf.w, "%s %s = %d; ", id, name, ev.Value)
+		}
+		gf.w.WriteString(")")
+
+		return nil
+
+	default:
+		fmt.Fprintf(&gf.w, "type %s ", name)
+		return gf.writeTypeLit(v, 0)
+	}
+}
+
+// writeType outputs the name of a named type or a literal describing the type.
+//
+// It encodes https://golang.org/ref/spec#Types.
+//
+//     foo                  (if foo is a named type)
+//     uint32
+func (gf *GoFormatter) writeType(typ Type, depth int) error {
+	typ = skipQualifiers(typ)
+
+	name := gf.Names[typ]
+	if name != "" {
+		gf.w.WriteString(name)
+		return nil
+	}
+
+	return gf.writeTypeLit(typ, depth)
+}
+
+// writeTypeLit outputs a literal describing the type.
+//
+// The function ignores named types.
+//
+// It encodes https://golang.org/ref/spec#TypeLit.
+//
+//     struct { bar uint32; }
+//     uint32
+func (gf *GoFormatter) writeTypeLit(typ Type, depth int) error {
+	depth++
+	if depth > maxTypeDepth {
+		return errNestedTooDeep
+	}
+
+	var err error
+	switch v := skipQualifiers(typ).(type) {
+	case *Int:
+		gf.writeIntLit(v)
+
+	case *Enum:
+		gf.w.WriteString("int32")
+
+	case *Typedef:
+		err = gf.writeType(v.Type, depth)
+
+	case *Array:
+		fmt.Fprintf(&gf.w, "[%d]", v.Nelems)
+		err = gf.writeType(v.Type, depth)
+
+	case *Struct:
+		err = gf.writeStructLit(v.Size, v.Members, depth)
+
+	case *Union:
+		// Always choose the first member to represent the union in Go.
+		err = gf.writeStructLit(v.Size, v.Members[:1], depth)
+
+	case *Datasec:
+		err = gf.writeDatasecLit(v, depth)
+
+	default:
+		return fmt.Errorf("type %T: %w", v, ErrNotSupported)
+	}
+
+	if err != nil {
+		return fmt.Errorf("%s: %w", typ, err)
+	}
+
+	return nil
+}
+
+func (gf *GoFormatter) writeIntLit(i *Int) {
+	// NB: Encoding.IsChar is ignored.
+	if i.Encoding.IsBool() && i.Size == 1 {
+		gf.w.WriteString("bool")
+		return
+	}
+
+	bits := i.Size * 8
+	if i.Encoding.IsSigned() {
+		fmt.Fprintf(&gf.w, "int%d", bits)
+	} else {
+		fmt.Fprintf(&gf.w, "uint%d", bits)
+	}
+}
+
+func (gf *GoFormatter) writeStructLit(size uint32, members []Member, depth int) error {
+	gf.w.WriteString("struct { ")
+
+	prevOffset := uint32(0)
+	skippedBitfield := false
+	for i, m := range members {
+		if m.BitfieldSize > 0 {
+			skippedBitfield = true
+			continue
+		}
+
+		offset := m.Offset.Bytes()
+		if n := offset - prevOffset; skippedBitfield && n > 0 {
+			fmt.Fprintf(&gf.w, "_ [%d]byte /* unsupported bitfield */; ", n)
+		} else {
+			gf.writePadding(n)
+		}
+
+		size, err := Sizeof(m.Type)
+		if err != nil {
+			return fmt.Errorf("field %d: %w", i, err)
+		}
+		prevOffset = offset + uint32(size)
+
+		if err := gf.writeStructField(m, depth); err != nil {
+			return fmt.Errorf("field %d: %w", i, err)
+		}
+	}
+
+	gf.writePadding(size - prevOffset)
+	gf.w.WriteString("}")
+	return nil
+}
+
+func (gf *GoFormatter) writeStructField(m Member, depth int) error {
+	if m.BitfieldSize > 0 {
+		return fmt.Errorf("bitfields are not supported")
+	}
+	if m.Offset%8 != 0 {
+		return fmt.Errorf("unsupported offset %d", m.Offset)
+	}
+
+	if m.Name == "" {
+		// Special case a nested anonymous union like
+		//     struct foo { union { int bar; int baz }; }
+		// by replacing the whole union with its first member.
+		union, ok := m.Type.(*Union)
+		if !ok {
+			return fmt.Errorf("anonymous fields are not supported")
+
+		}
+
+		if len(union.Members) == 0 {
+			return errors.New("empty anonymous union")
+		}
+
+		depth++
+		if depth > maxTypeDepth {
+			return errNestedTooDeep
+		}
+
+		m := union.Members[0]
+		size, err := Sizeof(m.Type)
+		if err != nil {
+			return err
+		}
+
+		if err := gf.writeStructField(m, depth); err != nil {
+			return err
+		}
+
+		gf.writePadding(union.Size - uint32(size))
+		return nil
+
+	}
+
+	fmt.Fprintf(&gf.w, "%s ", gf.identifier(m.Name))
+
+	if err := gf.writeType(m.Type, depth); err != nil {
+		return err
+	}
+
+	gf.w.WriteString("; ")
+	return nil
+}
+
+func (gf *GoFormatter) writeDatasecLit(ds *Datasec, depth int) error {
+	gf.w.WriteString("struct { ")
+
+	prevOffset := uint32(0)
+	for i, vsi := range ds.Vars {
+		v := vsi.Type.(*Var)
+		if v.Linkage != GlobalVar {
+			// Ignore static, extern, etc. for now.
+			continue
+		}
+
+		if v.Name == "" {
+			return fmt.Errorf("variable %d: empty name", i)
+		}
+
+		gf.writePadding(vsi.Offset - prevOffset)
+		prevOffset = vsi.Offset + vsi.Size
+
+		fmt.Fprintf(&gf.w, "%s ", gf.identifier(v.Name))
+
+		if err := gf.writeType(v.Type, depth); err != nil {
+			return fmt.Errorf("variable %d: %w", i, err)
+		}
+
+		gf.w.WriteString("; ")
+	}
+
+	gf.writePadding(ds.Size - prevOffset)
+	gf.w.WriteString("}")
+	return nil
+}
+
+func (gf *GoFormatter) writePadding(bytes uint32) {
+	if bytes > 0 {
+		fmt.Fprintf(&gf.w, "_ [%d]byte; ", bytes)
+	}
+}
+
+func skipQualifiers(typ Type) Type {
+	result := typ
+	for depth := 0; depth <= maxTypeDepth; depth++ {
+		switch v := (result).(type) {
+		case qualifier:
+			result = v.qualify()
+		default:
+			return result
+		}
+	}
+	return &cycle{typ}
+}