1 files changed, 311 insertions, 0 deletions
diff --git a/modules/packages/rubygems/marshal.go b/modules/packages/rubygems/marshal.go
new file mode 100644
index 0000000000..2c45042fa8
--- /dev/null
+++ b/modules/packages/rubygems/marshal.go
@@ -0,0 +1,311 @@
+// Copyright 2021 The Gitea Authors. All rights reserved.
+// Use of this source code is governed by a MIT-style
+// license that can be found in the LICENSE file.
+
+package rubygems
+
+import (
+	"bufio"
+	"bytes"
+	"errors"
+	"io"
+	"reflect"
+)
+
+const (
+	majorVersion = 4
+	minorVersion = 8
+
+	typeNil         = '0'
+	typeTrue        = 'T'
+	typeFalse       = 'F'
+	typeFixnum      = 'i'
+	typeString      = '"'
+	typeSymbol      = ':'
+	typeSymbolLink  = ';'
+	typeArray       = '['
+	typeIVar        = 'I'
+	typeUserMarshal = 'U'
+	typeUserDef     = 'u'
+	typeObject      = 'o'
+)
+
+var (
+	// ErrUnsupportedType indicates an unsupported type
+	ErrUnsupportedType = errors.New("Type is unsupported")
+	// ErrInvalidIntRange indicates an invalid number range
+	ErrInvalidIntRange = errors.New("Number is not in valid range")
+)
+
+// RubyUserMarshal is a Ruby object that has a marshal_load function.
+type RubyUserMarshal struct {
+	Name  string
+	Value interface{}
+}
+
+// RubyUserDef is a Ruby object that has a _load function.
+type RubyUserDef struct {
+	Name  string
+	Value interface{}
+}
+
+// RubyObject is a default Ruby object.
+type RubyObject struct {
+	Name   string
+	Member map[string]interface{}
+}
+
+// MarshalEncoder mimics Rubys Marshal class.
+// Note: Only supports types used by the RubyGems package registry.
+type MarshalEncoder struct {
+	w       *bufio.Writer
+	symbols map[string]int
+}
+
+// NewMarshalEncoder creates a new MarshalEncoder
+func NewMarshalEncoder(w io.Writer) *MarshalEncoder {
+	return &MarshalEncoder{
+		w:       bufio.NewWriter(w),
+		symbols: map[string]int{},
+	}
+}
+
+// Encode encodes the given type
+func (e *MarshalEncoder) Encode(v interface{}) error {
+	if _, err := e.w.Write([]byte{majorVersion, minorVersion}); err != nil {
+		return err
+	}
+
+	if err := e.marshal(v); err != nil {
+		return err
+	}
+
+	return e.w.Flush()
+}
+
+func (e *MarshalEncoder) marshal(v interface{}) error {
+	if v == nil {
+		return e.marshalNil()
+	}
+
+	val := reflect.ValueOf(v)
+	typ := reflect.TypeOf(v)
+
+	if typ.Kind() == reflect.Ptr {
+		val = val.Elem()
+		typ = typ.Elem()
+	}
+
+	switch typ.Kind() {
+	case reflect.Bool:
+		return e.marshalBool(val.Bool())
+	case reflect.Int, reflect.Int8, reflect.Int16, reflect.Int32:
+		return e.marshalInt(val.Int())
+	case reflect.String:
+		return e.marshalString(val.String())
+	case reflect.Slice, reflect.Array:
+		return e.marshalArray(val)
+	}
+
+	switch typ.Name() {
+	case "RubyUserMarshal":
+		return e.marshalUserMarshal(val.Interface().(RubyUserMarshal))
+	case "RubyUserDef":
+		return e.marshalUserDef(val.Interface().(RubyUserDef))
+	case "RubyObject":
+		return e.marshalObject(val.Interface().(RubyObject))
+	}
+
+	return ErrUnsupportedType
+}
+
+func (e *MarshalEncoder) marshalNil() error {
+	return e.w.WriteByte(typeNil)
+}
+
+func (e *MarshalEncoder) marshalBool(b bool) error {
+	if b {
+		return e.w.WriteByte(typeTrue)
+	}
+	return e.w.WriteByte(typeFalse)
+}
+
+func (e *MarshalEncoder) marshalInt(i int64) error {
+	if err := e.w.WriteByte(typeFixnum); err != nil {
+		return err
+	}
+
+	return e.marshalIntInternal(i)
+}
+
+func (e *MarshalEncoder) marshalIntInternal(i int64) error {
+	if i == 0 {
+		return e.w.WriteByte(0)
+	} else if 0 < i && i < 123 {
+		return e.w.WriteByte(byte(i + 5))
+	} else if -124 < i && i <= -1 {
+		return e.w.WriteByte(byte(i - 5))
+	}
+
+	var len int
+	if 122 < i && i <= 0xff {
+		len = 1
+	} else if 0xff < i && i <= 0xffff {
+		len = 2
+	} else if 0xffff < i && i <= 0xffffff {
+		len = 3
+	} else if 0xffffff < i && i <= 0x3fffffff {
+		len = 4
+	} else if -0x100 <= i && i < -123 {
+		len = -1
+	} else if -0x10000 <= i && i < -0x100 {
+		len = -2
+	} else if -0x1000000 <= i && i < -0x100000 {
+		len = -3
+	} else if -0x40000000 <= i && i < -0x1000000 {
+		len = -4
+	} else {
+		return ErrInvalidIntRange
+	}
+
+	if err := e.w.WriteByte(byte(len)); err != nil {
+		return err
+	}
+	if len < 0 {
+		len = -len
+	}
+
+	for c := 0; c < len; c++ {
+		if err := e.w.WriteByte(byte(i >> uint(8*c) & 0xff)); err != nil {
+			return err
+		}
+	}
+
+	return nil
+}
+
+func (e *MarshalEncoder) marshalString(str string) error {
+	if err := e.w.WriteByte(typeIVar); err != nil {
+		return err
+	}
+
+	if err := e.marshalRawString(str); err != nil {
+		return err
+	}
+
+	if err := e.marshalIntInternal(1); err != nil {
+		return err
+	}
+
+	if err := e.marshalSymbol("E"); err != nil {
+		return err
+	}
+
+	return e.marshalBool(true)
+}
+
+func (e *MarshalEncoder) marshalRawString(str string) error {
+	if err := e.w.WriteByte(typeString); err != nil {
+		return err
+	}
+
+	if err := e.marshalIntInternal(int64(len(str))); err != nil {
+		return err
+	}
+
+	_, err := e.w.WriteString(str)
+	return err
+}
+
+func (e *MarshalEncoder) marshalSymbol(str string) error {
+	if index, ok := e.symbols[str]; ok {
+		if err := e.w.WriteByte(typeSymbolLink); err != nil {
+			return err
+		}
+		return e.marshalIntInternal(int64(index))
+	}
+
+	e.symbols[str] = len(e.symbols)
+
+	if err := e.w.WriteByte(typeSymbol); err != nil {
+		return err
+	}
+
+	if err := e.marshalIntInternal(int64(len(str))); err != nil {
+		return err
+	}
+
+	_, err := e.w.WriteString(str)
+	return err
+}
+
+func (e *MarshalEncoder) marshalArray(arr reflect.Value) error {
+	if err := e.w.WriteByte(typeArray); err != nil {
+		return err
+	}
+
+	len := arr.Len()
+
+	if err := e.marshalIntInternal(int64(len)); err != nil {
+		return err
+	}
+
+	for i := 0; i < len; i++ {
+		if err := e.marshal(arr.Index(i).Interface()); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (e *MarshalEncoder) marshalUserMarshal(userMarshal RubyUserMarshal) error {
+	if err := e.w.WriteByte(typeUserMarshal); err != nil {
+		return err
+	}
+
+	if err := e.marshalSymbol(userMarshal.Name); err != nil {
+		return err
+	}
+
+	return e.marshal(userMarshal.Value)
+}
+
+func (e *MarshalEncoder) marshalUserDef(userDef RubyUserDef) error {
+	var buf bytes.Buffer
+	if err := NewMarshalEncoder(&buf).Encode(userDef.Value); err != nil {
+		return err
+	}
+
+	if err := e.w.WriteByte(typeUserDef); err != nil {
+		return err
+	}
+	if err := e.marshalSymbol(userDef.Name); err != nil {
+		return err
+	}
+	if err := e.marshalIntInternal(int64(buf.Len())); err != nil {
+		return err
+	}
+	_, err := e.w.Write(buf.Bytes())
+	return err
+}
+
+func (e *MarshalEncoder) marshalObject(obj RubyObject) error {
+	if err := e.w.WriteByte(typeObject); err != nil {
+		return err
+	}
+	if err := e.marshalSymbol(obj.Name); err != nil {
+		return err
+	}
+	if err := e.marshalIntInternal(int64(len(obj.Member))); err != nil {
+		return err
+	}
+	for k, v := range obj.Member {
+		if err := e.marshalSymbol(k); err != nil {
+			return err
+		}
+		if err := e.marshal(v); err != nil {
+			return err
+		}
+	}
+	return nil
+}