From 5e80e00d2e103424dcddfd061c817189026fb1da Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Valentin=20W=C3=BCstholz?= <wuestholz@gmail.com>
Date: Tue, 23 May 2017 10:43:22 +0200
Subject: [PATCH] core/vm: enable optional EVM error collection in interpreter

---
 core/vm/evm.go         |  5 +++++
 core/vm/interpreter.go | 17 +++++++++++++++++
 2 files changed, 22 insertions(+)

diff --git a/core/vm/evm.go b/core/vm/evm.go
index 69c8ec4787..94d1779ccd 100644
--- a/core/vm/evm.go
+++ b/core/vm/evm.go
@@ -104,6 +104,11 @@ type EVM struct {
 	// global (to this context) ethereum virtual machine
 	// used throughout the execution of the tx.
 	interpreter *Interpreter
+	// InterpreterErrors contain the errors returned by the EVM. The errors
+	// aren't consensus errors but rather errors that were returned by
+	// invalid opcodes, stack over and underflow, etc. This slice will only
+	// be populated if the CollectEVMErrors option is enabled.
+	InterpreterErrors []EVMError
 	// abort is used to abort the EVM calling operations
 	// NOTE: must be set atomically
 	abort int32
diff --git a/core/vm/interpreter.go b/core/vm/interpreter.go
index 0d6038cbbf..f6aeeb9ffc 100644
--- a/core/vm/interpreter.go
+++ b/core/vm/interpreter.go
@@ -28,6 +28,8 @@ import (
 type Config struct {
 	// Debug enabled debugging Interpreter options
 	Debug bool
+	// CollectEVMErrors enables EVM error collecting
+	CollectEVMErrors bool
 	// Tracer is the op code logger
 	Tracer Tracer
 	// NoRecursion disabled Interpreter call, callcode,
@@ -41,6 +43,15 @@ type Config struct {
 	JumpTable [256]operation
 }
 
+type EVMError struct {
+	Err   error
+	Depth int
+}
+
+func (e EVMError) Error() string {
+	return fmt.Sprintf("%d: %v", e.Depth, e.Err)
+}
+
 // Interpreter is used to run Ethereum based contracts and will utilise the
 // passed environment to query external sources for state information.
 // The Interpreter will run the byte code VM based on the passed
@@ -154,6 +165,12 @@ func (in *Interpreter) Run(contract *Contract, input []byte) (ret []byte, err er
 			}
 		}()
 	}
+	if in.cfg.CollectEVMErrors {
+		defer func() {
+			in.evm.InterpreterErrors = append(in.evm.InterpreterErrors, EVMError{Err: err, Depth: in.evm.depth})
+		}()
+	}
+
 	// The Interpreter main run loop (contextual). This loop runs until either an
 	// explicit STOP, RETURN or SELFDESTRUCT is executed, an error occurred during
 	// the execution of one of the operations or until the done flag is set by the