1 // Copyright 2017 The Go Authors. All rights reserved. 2 // Use of this source code is governed by a BSD-style 3 // license that can be found in the LICENSE file. 4 5 // The bug happened like this: 6 // 1. The main binary adds an itab for *json.UnsupportedValueError / error 7 // (concrete type / interface type). This itab goes in hash bucket 0x111. 8 // 2. The plugin adds that same itab again. That makes a cycle in the itab 9 // chain rooted at hash bucket 0x111. 10 // 3. The main binary then asks for the itab for *dynamodbstreamsevt.Event / 11 // json.Unmarshaler. This itab happens to also live in bucket 0x111. 12 // The lookup code goes into an infinite loop searching for this itab. 13 // 14 // The code is carefully crafted so that the two itabs are both from the 15 // same bucket, and so that the second itab doesn't exist in 16 // the itab hashmap yet (so the entire linked list must be searched). 17 package main 18 19 import ( 20 "encoding/json" 21 "plugin" 22 "testplugin/issue18676/dynamodbstreamsevt" 23 ) 24 25 func main() { 26 plugin.Open("plugin.so") 27 28 var x interface{} = (*dynamodbstreamsevt.Event)(nil) 29 if _, ok := x.(json.Unmarshaler); !ok { 30 println("something") 31 } 32 } 33