From d7518e31513731a843d78b4d55e2c9a989de7610 Mon Sep 17 00:00:00 2001
From: Masaaki Goshima <goccy54@gmail.com>
Date: Fri, 21 Aug 2020 01:01:24 +0900
Subject: [PATCH] Fix seenPtr

---
 encode.go        | 2 --
 encode_opcode.go | 5 +++--
 encode_vm.go     | 9 +++++----
 3 files changed, 8 insertions(+), 8 deletions(-)

diff --git a/encode.go b/encode.go
index d3590d5..f41114e 100644
--- a/encode.go
+++ b/encode.go
@@ -22,7 +22,6 @@ type Encoder struct {
 	indent                         int
 	structTypeToCompiledCode       map[uintptr]*compiledCode
 	structTypeToCompiledIndentCode map[uintptr]*compiledCode
-	seenPtr                        map[uintptr]struct{}
 }
 
 type compiledCode struct {
@@ -68,7 +67,6 @@ func init() {
 				buf:                            make([]byte, 0, bufSize),
 				structTypeToCompiledCode:       map[uintptr]*compiledCode{},
 				structTypeToCompiledIndentCode: map[uintptr]*compiledCode{},
-				seenPtr:                        map[uintptr]struct{}{},
 			}
 		},
 	}
diff --git a/encode_opcode.go b/encode_opcode.go
index f67065e..9fef8bf 100644
--- a/encode_opcode.go
+++ b/encode_opcode.go
@@ -478,7 +478,8 @@ func (c *interfaceCode) copy(codeMap map[uintptr]*opcode) *opcode {
 
 type recursiveCode struct {
 	*opcodeHeader
-	jmp *compiledCode
+	jmp     *compiledCode
+	seenPtr uintptr
 }
 
 func (c *recursiveCode) copy(codeMap map[uintptr]*opcode) *opcode {
@@ -489,7 +490,7 @@ func (c *recursiveCode) copy(codeMap map[uintptr]*opcode) *opcode {
 	if code, exists := codeMap[addr]; exists {
 		return code
 	}
-	recur := &recursiveCode{}
+	recur := &recursiveCode{seenPtr: c.seenPtr}
 	code := (*opcode)(unsafe.Pointer(recur))
 	codeMap[addr] = code
 
diff --git a/encode_vm.go b/encode_vm.go
index ab81e07..e2d0971 100644
--- a/encode_vm.go
+++ b/encode_vm.go
@@ -12,6 +12,7 @@ import (
 )
 
 func (e *Encoder) run(code *opcode) error {
+	seenPtr := map[uintptr]struct{}{}
 	for {
 		switch code.op {
 		case opPtr:
@@ -80,13 +81,13 @@ func (e *Encoder) run(code *opcode) error {
 				typ: ifaceCode.typ,
 				ptr: unsafe.Pointer(ptr),
 			}))
-			if _, exists := e.seenPtr[ptr]; exists {
+			if _, exists := seenPtr[ptr]; exists {
 				return &UnsupportedValueError{
 					Value: reflect.ValueOf(v),
 					Str:   fmt.Sprintf("encountered a cycle via %s", code.typ),
 				}
 			}
-			e.seenPtr[ptr] = struct{}{}
+			seenPtr[ptr] = struct{}{}
 			rv := reflect.ValueOf(v)
 			if rv.IsNil() {
 				e.encodeNull()
@@ -505,7 +506,7 @@ func (e *Encoder) run(code *opcode) error {
 			code = c.next
 		case opStructFieldRecursive:
 			recursive := code.toRecursiveCode()
-			if _, exists := e.seenPtr[recursive.ptr]; exists {
+			if recursive.seenPtr != 0 && recursive.seenPtr == recursive.ptr {
 				v := *(*interface{})(unsafe.Pointer(&interfaceHeader{
 					typ: code.typ,
 					ptr: unsafe.Pointer(recursive.ptr),
@@ -515,7 +516,7 @@ func (e *Encoder) run(code *opcode) error {
 					Str:   fmt.Sprintf("encountered a cycle via %s", code.typ),
 				}
 			}
-			e.seenPtr[recursive.ptr] = struct{}{}
+			recursive.seenPtr = recursive.ptr
 			if err := e.run(newRecursiveCode(recursive)); err != nil {
 				return err
 			}