romichan/protobuf

lightweight and fast protobuf support for go

protobuf's Issues

feature: support oneof

Todo:

• code generate
• encode support
• decode support

当结构体字段的内容长度为0x7F时，字段size计算错误

复现代码

package main

import (
	"encoding/hex"
	"fmt"
	"github.com/RomiChan/protobuf/proto" // v0.1.1-0.20220524030518-4f349493f9da
)

type ST1 struct {
	ST *ST2 `protobuf:"bytes,1,opt"`
}

type ST2 struct {
	ST *ST3 `protobuf:"bytes,1,opt"`
}

type ST3 struct {
	Str []byte `protobuf:"bytes,1,opt"`
}

func main() {
	st := &ST1{&ST2{&ST3{
		Str: make([]byte, 0x7D),
	}}}
	b, _ := proto.Marshal(st)
	fmt.Println(hex.Dump(b))

	st.ST = nil
	err := proto.Unmarshal(b, st)
	if err != nil {
		fmt.Println(err)
	}
}

输出结果

00000000  0a 82 01 0a 7f 0a 7d 00  00 00 00 00 00 00 00 00  |......}.........|
00000010  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000020  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000030  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000040  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000050  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000060  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000070  00 00 00 00 00 00 00 00  00 00 00 00 00 00 00 00  |................|
00000080  00 00 00 00                                       |....|            

field number 1 with wire type 2: unexpected EOF

原因

在 \proto\walker.go 中，计算内容长度时误把tagsize算了进去

...
func (w *walker) structCodec(t reflect.Type) *codec {
	...
	c.size = func(p unsafe.Pointer, f *structField) int {
		p = deref(p)
		if p != nil {
			n := info.size(p) + f.tagsize	// ？？？
			n += sizeOfVarint(uint64(n))
			return n
		}
		return 0
	}
	...
}
...

更改为以下代码即可

...
func (w *walker) structCodec(t reflect.Type) *codec {
	...
	c.size = func(p unsafe.Pointer, f *structField) int {
		p = deref(p)
		if p != nil {
			n := info.size(p)
			n += sizeOfVarint(uint64(n)) + f.tagsize	// √
			return n
		}
		return 0
	}
	...
}
...