From 5709315d60aeaad7b406c5176d22d158b2c0ee11 Mon Sep 17 00:00:00 2001
From: laizy <laizy@users.noreply.github.com>
Date: Fri, 11 Oct 2019 11:22:14 +0800
Subject: [PATCH] allow vm reader eof error to avoid hard-fork in testnet
 (#1092)

---
 core/store/ledgerstore/ledger_store.go |  3 ++-
 smartcontract/smart_contract.go        |  1 +
 vm/neovm/execution_context.go          | 24 ++++++++++++++----------
 vm/neovm/executor.go                   |  5 +++--
 vm/neovm/utils/vm_reader.go            |  9 ++++++++-
 5 files changed, 28 insertions(+), 14 deletions(-)

diff --git a/core/store/ledgerstore/ledger_store.go b/core/store/ledgerstore/ledger_store.go
index cda8c3ae61..4ff8b7fe8f 100644
--- a/core/store/ledgerstore/ledger_store.go
+++ b/core/store/ledgerstore/ledger_store.go
@@ -850,7 +850,8 @@ func (this *LedgerStoreImp) saveBlock(block *types.Block, stateMerkleRoot common
 	}
 
 	if result.MerkleRoot != stateMerkleRoot {
-		return errors.NewErr("state merkle root mismatch!")
+		return fmt.Errorf("state merkle root mismatch. expected: %s, got: %s",
+			result.MerkleRoot.ToHexString(), stateMerkleRoot.ToHexString())
 	}
 
 	return this.submitBlock(block, result)
diff --git a/smartcontract/smart_contract.go b/smartcontract/smart_contract.go
index d592b96f76..555c0d2dd3 100644
--- a/smartcontract/smart_contract.go
+++ b/smartcontract/smart_contract.go
@@ -128,6 +128,7 @@ func NewVmFeatureFlag(blockHeight uint32) vm.VmFeatureFlag {
 	var feature vm.VmFeatureFlag
 	enableHeight := config.GetOpcodeUpdateCheckHeight(config.DefConfig.P2PNode.NetworkId)
 	feature.DisableHasKey = blockHeight <= enableHeight
+	feature.AllowReaderEOF = blockHeight <= enableHeight
 
 	return feature
 }
diff --git a/vm/neovm/execution_context.go b/vm/neovm/execution_context.go
index 05d8b1876c..4cc8ae79b5 100644
--- a/vm/neovm/execution_context.go
+++ b/vm/neovm/execution_context.go
@@ -28,14 +28,18 @@ type ExecutionContext struct {
 	Code               []byte
 	OpReader           *utils.VmReader
 	InstructionPointer int
+	vmFlags            VmFeatureFlag
 }
 
-func NewExecutionContext(code []byte) *ExecutionContext {
-	var executionContext ExecutionContext
-	executionContext.Code = code
-	executionContext.OpReader = utils.NewVmReader(code)
-	executionContext.InstructionPointer = 0
-	return &executionContext
+func NewExecutionContext(code []byte, flag VmFeatureFlag) *ExecutionContext {
+	var context ExecutionContext
+	context.Code = code
+	context.OpReader = utils.NewVmReader(code)
+	context.OpReader.AllowEOF = flag.AllowReaderEOF
+	context.vmFlags = flag
+
+	context.InstructionPointer = 0
+	return &context
 }
 
 func (ec *ExecutionContext) GetInstructionPointer() int {
@@ -62,8 +66,8 @@ func (self *ExecutionContext) ReadOpCode() (val OpCode, eof bool) {
 }
 
 func (ec *ExecutionContext) Clone() *ExecutionContext {
-	executionContext := NewExecutionContext(ec.Code)
-	executionContext.InstructionPointer = ec.InstructionPointer
-	_ = executionContext.SetInstructionPointer(int64(ec.GetInstructionPointer()))
-	return executionContext
+	context := NewExecutionContext(ec.Code, ec.vmFlags)
+	context.InstructionPointer = ec.InstructionPointer
+	_ = context.SetInstructionPointer(int64(ec.GetInstructionPointer()))
+	return context
 }
diff --git a/vm/neovm/executor.go b/vm/neovm/executor.go
index 4c22677f09..91ac078bae 100644
--- a/vm/neovm/executor.go
+++ b/vm/neovm/executor.go
@@ -33,14 +33,15 @@ import (
 )
 
 type VmFeatureFlag struct {
-	DisableHasKey bool // disable haskey, dcall, values opcode
+	DisableHasKey  bool // disable haskey, dcall, values opcode
+	AllowReaderEOF bool // allow VmReader.ReadBytes got EOF and return 0 bytes
 }
 
 func NewExecutor(code []byte, feature VmFeatureFlag) *Executor {
 	var engine Executor
 	engine.EvalStack = NewValueStack(STACK_LIMIT)
 	engine.AltStack = NewValueStack(STACK_LIMIT)
-	context := NewExecutionContext(code)
+	context := NewExecutionContext(code, feature)
 	engine.Context = context
 	engine.State = BREAK
 	engine.Features = feature
diff --git a/vm/neovm/utils/vm_reader.go b/vm/neovm/utils/vm_reader.go
index 5e4fc9e516..ad2385cdb9 100644
--- a/vm/neovm/utils/vm_reader.go
+++ b/vm/neovm/utils/vm_reader.go
@@ -27,6 +27,7 @@ import (
 type VmReader struct {
 	reader     *bytes.Reader
 	BaseStream []byte
+	AllowEOF   bool // allow VmReader.ReadBytes got EOF and return 0 bytes
 }
 
 func NewVmReader(b []byte) *VmReader {
@@ -43,10 +44,16 @@ func (r *VmReader) ReadByte() (byte, error) {
 
 func (r *VmReader) ReadBytes(count int) ([]byte, error) {
 	// first check to avoid memory attack
-	if r.reader.Len() < count {
+	amount := r.reader.Len()
+	if r.AllowEOF {
+		amount = 1 * 1024 * 1024
+	}
+	if amount < count {
 		return nil, io.EOF
 	}
 	b := make([]byte, count)
+	// when reader does not has enough bytes, it will return the actual length and error is nil
+	// this is a bug previously(it should use io.ReadFull), but we have to keep it to avoid hard fork
 	_, err := r.reader.Read(b)
 	if err != nil {
 		return nil, err