jsoniter stack overflow

[charles-d-burton]

The following program sample.go triggers an unexpected result

package main

import (
	"fmt"
	"os"

	"github.com/traefik/yaegi/interp"
	"github.com/traefik/yaegi/stdlib"
	"github.com/traefik/yaegi/stdlib/unsafe"
)

func main() {
	fmt.Println("loading source file")

	/*zipfile := "./source.zip"

	zf, err := zip.OpenReader(zipfile)
	if err != nil {
		fmt.Println(err)
	}*/
	zf := os.DirFS("./source")

	fmt.Println("generating options")
	options := interp.Options{
		//		GoPath:               "/home/charles/Development/ziploader/loader/source",
		SourcecodeFilesystem: zf,
		//SourcecodeFilesystem: &zf.Reader,
	}

	fmt.Println("loading interp")
	i := interp.New(options)

	fmt.Println("loading stdlb")
	if err := i.Use(stdlib.Symbols); err != nil {
		fmt.Println(err)
	}

	if err := i.Use(interp.Symbols); err != nil {
		fmt.Println(err)
	}

	if err := i.Use(unsafe.Symbols); err != nil {
		fmt.Println(err)
	}

	fmt.Println("evaluating source")
	_, err := i.EvalPath(`./`)
	if err != nil {
		fmt.Println(err)
	}
}

Expected result

go run ./main.go
{"hello":"world"}

Got

loading source file
generating options
loading interp
loading stdlb
evaluating source
runtime: goroutine stack exceeds 1000000000-byte limit
runtime: sp=0xc023700410 stack=[0xc023700000, 0xc043700000]
fatal error: stack overflow

runtime stack:
runtime.throw({0xdfae79?, 0x1432860?})
	/usr/lib/go-1.18/src/runtime/panic.go:992 +0x71
runtime.newstack()
	/usr/lib/go-1.18/src/runtime/stack.go:1101 +0x5cc
runtime.morestack()
	/usr/lib/go-1.18/src/runtime/asm_amd64.s:547 +0x8b

goroutine 1 [running]:
runtime.heapBitsSetType(0xc006459040?, 0xd0?, 0xc8?, 0xd9df80?)
	/usr/lib/go-1.18/src/runtime/mbitmap.go:832 +0xbcc fp=0xc023700420 sp=0xc023700418 pc=0x41a9ec
runtime.mallocgc(0xc8, 0xd9df80, 0x1)
	/usr/lib/go-1.18/src/runtime/malloc.go:1117 +0x673 fp=0xc023700498 sp=0xc023700420 pc=0x411fd3
runtime.newobject(0xc023700520?)
	/usr/lib/go-1.18/src/runtime/malloc.go:1259 +0x27 fp=0xc0237004c0 sp=0xc023700498 pc=0x412387
os.statNolog({0xc000150630, 0x2f})
	/usr/lib/go-1.18/src/os/stat_unix.go:30 +0x2e fp=0xc023700510 sp=0xc0237004c0 pc=0x5026ae
os.Stat({0xc000150630, 0x2f})
	/usr/lib/go-1.18/src/os/stat.go:13 +0x34 fp=0xc023700530 sp=0xc023700510 pc=0x502214
os.dirFS.Stat({0xdf0026, 0x8}, {0xc000150600, 0x26})
	/usr/lib/go-1.18/src/os/file.go:658 +0x6a fp=0xc023700578 sp=0xc023700530 pc=0x4fd6aa
os.(*dirFS).Stat(0x0?, {0xc000150600?, 0xc000114110?})
	<autogenerated>:1 +0x3f fp=0xc0237005a8 sp=0xc023700578 pc=0x50427f
io/fs.Stat({0xfb9720, 0xc000114110}, {0xc000150600, 0x26})
	/usr/lib/go-1.18/src/io/fs/stat.go:22 +0x167 fp=0xc023700628 sp=0xc0237005a8 pc=0x4eabc7
github.com/traefik/yaegi/interp.(*Interpreter).pkgDir(0xc00033a000, {0x0, 0x0}, {0xfb4118, 0x1}, {0xc0002a2061, 0x1b})
	/home/charles/Development/go/pkg/mod/github.com/traefik/yaegi@v0.13.0/interp/src.go:200 +0x18c fp=0xc023700770 sp=0xc023700628 pc=0x6c264c
github.com/traefik/yaegi/interp.(*Interpreter).pkgDir(0xc00033a000, {0x0, 0x0}, {0xfb4118, 0x1}, {0xc0002a2061, 0x1b})
	/home/charles/Development/go/pkg/mod/github.com/traefik/yaegi@v0.13.0/interp/src.go:223 +0x489 fp=0xc0237008b8 sp=0xc023700770 pc=0x6c2949
github.com/traefik/yaegi/interp.(*Interpreter).pkgDir(0xc00033a000, {0x0, 0x0}, {0xfb4118, 0x1}, {0xc0002a2061, 0x1b})
	/home/charles/Development/go/pkg/mod/github.com/traefik/yaegi@v0.13.0/interp/src.go:223 +0x489 fp=0xc023700a00 sp=0xc0237008b8 pc=0x6c2949
github.com/traefik/yaegi/interp.(*Interpreter).pkgDir(0xc00033a000, {0x0, 0x0}, {0xfb4118, 0x1}, {0xc0002a2061, 0x1b})
	/home/charles/Development/go/pkg/mod/github.com/traefik/yaegi@v0.13.0/interp/src.go:223 +0x489 fp=0xc023700b48 sp=0xc023700a00 pc=0x6c2949
github.com/traefik/yaegi/interp.(*Interpreter).pkgDir(0xc00033a000, {0x0, 0x0}, {0xfb4118, 0x1}, {0xc0002a2061, 0x1b})
	/home/charles/Development/go/pkg/mod/github.com/traefik/yaegi@v0.13.0/interp/src.go:223 +0x489 fp=0xc023700c90 sp=0xc023700b48 pc=0x6c2949
github.com/traefik/yaegi/interp.(*Interpreter).pkgDir(0xc00033a000, {0x0, 0x0}, {0xfb4118, 0x1}, {0xc0002a2061, 0x1b})
	/home/charles/Development/go/pkg/mod/github.com/traefik/yaegi@v0.13.0/interp/src.go:223 +0x489 fp=0xc023700dd8 sp=0xc023700c90 pc=0x6c2949

Yaegi Version

v0.13.0

Additional Notes

Put the following code in a directory named source and run

go mod vendor

package main

import (
	"log"

	jsoniter "github.com/json-iterator/go"
)

var (
	json = jsoniter.ConfigCompatibleWithStandardLibrary
)

type Test struct {
	Hello string `json:"hello"`
}

func main() {
	hello := Test{"hello world"}
	data, err := json.Marshal(&hello)
	if err != nil {
		log.Println(err)
	}
	log.Println(string(data))
}

[mvertes]

A problem here is that in github.com/modern-go/reflect2 dependency package, there is some code which is fundamentally incompatible with yaegi, using some "//go:linkname" pragma to link to internal (unexported) stdlib symbols during compilation.

For ex. in https://github.com/modern-go/reflect2/blob/master/go_below_118.go line 12:

//go:linkname mapiterinit reflect.mapiterinit
func mapiterinit(rtype unsafe.Pointer, m unsafe.Pointer) (val *hiter)

There is no way yaegi (or another interpreter) can solve that from the pre-compiled runtime.

Of course yaegi should not panic here and gracefully abort those pathological cases. This is what I will fix, but unfortunately it will not make your code work.

[charles-d-burton]

All good! That makes perfect sense.