cmd, core, eth, params: implement flags to control dao fork blocks

4 files changed, 348 insertions, 44 deletions

diff --git a/cmd/geth/dao_test.go b/cmd/geth/dao_test.go
new file mode 100644
index 000000000..fd6831c15
--- /dev/null
+++ b/cmd/geth/dao_test.go
@@ -0,0 +1,306 @@
+// Copyright 2016 The go-ethereum Authors
+// This file is part of go-ethereum.
+//
+// go-ethereum is free software: you can redistribute it and/or modify
+// it under the terms of the GNU General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// go-ethereum is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU General Public License for more details.
+//
+// You should have received a copy of the GNU General Public License
+// along with go-ethereum. If not, see <http://www.gnu.org/licenses/>.
+
+package main
+
+import (
+	"io/ioutil"
+	"math/big"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/params"
+)
+
+var daoNoForkGenesis = `{
+	"alloc"      : {},
+	"coinbase"   : "0x0000000000000000000000000000000000000000",
+	"difficulty" : "0x20000",
+	"extraData"  : "",
+	"gasLimit"   : "0x2fefd8",
+	"nonce"      : "0x0000000000000042",
+	"mixhash"    : "0x0000000000000000000000000000000000000000000000000000000000000000",
+	"parentHash" : "0x0000000000000000000000000000000000000000000000000000000000000000",
+	"timestamp"  : "0x00"
+}`
+var daoNoForkGenesisHash = common.HexToHash("5e1fc79cb4ffa4739177b5408045cd5d51c6cf766133f23f7cd72ee1f8d790e0")
+
+var daoProForkGenesis = `{
+	"alloc"      : {},
+	"coinbase"   : "0x0000000000000000000000000000000000000000",
+	"difficulty" : "0x20000",
+	"extraData"  : "",
+	"gasLimit"   : "0x2fefd8",
+	"nonce"      : "0x0000000000000043",
+	"mixhash"    : "0x0000000000000000000000000000000000000000000000000000000000000000",
+	"parentHash" : "0x0000000000000000000000000000000000000000000000000000000000000000",
+	"timestamp"  : "0x00",
+	"config"     : {
+		"daoForkBlock": 314
+	}
+}`
+var daoProForkGenesisHash = common.HexToHash("c80f3c1c3d81ae6d8ea59edf35d3e4b723e4c8684ec71fdb6d4715e3f8add237")
+var daoProForkBlock = big.NewInt(314)
+
+// Tests that creating a new node to with or without the DAO fork flag will correctly
+// set the genesis block but with DAO support explicitly set or unset in the chain
+// config in the database.
+func TestDAOSupportMainnet(t *testing.T) {
+	testDAOForkBlockNewChain(t, false, "", true, params.MainNetDAOForkBlock)
+}
+func TestDAOSupportTestnet(t *testing.T) {
+	testDAOForkBlockNewChain(t, true, "", true, params.TestNetDAOForkBlock)
+}
+func TestDAOSupportPrivnet(t *testing.T) {
+	testDAOForkBlockNewChain(t, false, daoProForkGenesis, false, daoProForkBlock)
+}
+func TestDAONoSupportMainnet(t *testing.T) {
+	testDAOForkBlockNewChain(t, false, "", false, nil)
+}
+func TestDAONoSupportTestnet(t *testing.T) {
+	testDAOForkBlockNewChain(t, true, "", false, nil)
+}
+func TestDAONoSupportPrivnet(t *testing.T) {
+	testDAOForkBlockNewChain(t, false, daoNoForkGenesis, false, nil)
+}
+
+func testDAOForkBlockNewChain(t *testing.T, testnet bool, genesis string, fork bool, expect *big.Int) {
+	// Create a temporary data directory to use and inspect later
+	datadir := tmpdir(t)
+	defer os.RemoveAll(datadir)
+
+	// Start a Geth instance with the requested flags set and immediately terminate
+	if genesis != "" {
+		json := filepath.Join(datadir, "genesis.json")
+		if err := ioutil.WriteFile(json, []byte(genesis), 0600); err != nil {
+			t.Fatalf("failed to write genesis file: %v", err)
+		}
+		runGeth(t, "--datadir", datadir, "init", json).cmd.Wait()
+	}
+	execDAOGeth(t, datadir, testnet, fork, false)
+
+	// Retrieve the DAO config flag from the database
+	path := filepath.Join(datadir, "chaindata")
+	if testnet {
+		path = filepath.Join(datadir, "testnet", "chaindata")
+	}
+	db, err := ethdb.NewLDBDatabase(path, 0, 0)
+	if err != nil {
+		t.Fatalf("failed to open test database: %v", err)
+	}
+	defer db.Close()
+
+	genesisHash := common.HexToHash("0xd4e56740f876aef8c010b86a40d5f56745a118d0906a34e69aec8c0db1cb8fa3")
+	if testnet {
+		genesisHash = common.HexToHash("0x0cd786a2425d16f152c658316c423e6ce1181e15c3295826d7c9904cba9ce303")
+	} else if genesis == daoNoForkGenesis {
+		genesisHash = daoNoForkGenesisHash
+	} else if genesis == daoProForkGenesis {
+		genesisHash = daoProForkGenesisHash
+	}
+	config, err := core.GetChainConfig(db, genesisHash)
+	if err != nil {
+		t.Fatalf("failed to retrieve chain config: %v", err)
+	}
+	// Validate the DAO hard-fork block number against the expected value
+	if config.DAOForkBlock == nil {
+		if expect != nil {
+			t.Fatalf("dao hard-fork block mismatch: have nil, want %v", expect)
+		}
+	} else if config.DAOForkBlock.Cmp(expect) != 0 {
+		t.Fatalf("dao hard-fork block mismatch: have %v, want %v", config.DAOForkBlock, expect)
+	}
+}
+
+// Tests that starting up an already existing node with various DAO fork override
+// flags correctly changes the chain configs in the database.
+func TestDAODefaultMainnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, false, "", false, false, false, false, nil)
+}
+func TestDAOStartSupportMainnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, false, "", false, true, false, false, params.MainNetDAOForkBlock)
+}
+func TestDAOContinueExplicitSupportMainnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, false, "", true, true, false, false, params.MainNetDAOForkBlock)
+}
+func TestDAOContinueImplicitSupportMainnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, false, "", true, false, false, false, params.MainNetDAOForkBlock)
+}
+func TestDAOSwitchSupportMainnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, false, "", false, true, true, false, params.MainNetDAOForkBlock)
+}
+func TestDAOStartOpposeMainnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, false, "", false, false, false, true, nil)
+}
+func TestDAOContinueExplicitOpposeMainnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, false, "", false, false, true, true, nil)
+}
+func TestDAOContinueImplicitOpposeMainnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, false, "", false, false, true, false, nil)
+}
+func TestDAOSwitchOpposeMainnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, false, "", true, false, false, true, nil)
+}
+func TestDAODefaultTestnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, true, "", false, false, false, false, nil)
+}
+func TestDAOStartSupportTestnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, true, "", false, true, false, false, params.TestNetDAOForkBlock)
+}
+func TestDAOContinueExplicitSupportTestnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, true, "", true, true, false, false, params.TestNetDAOForkBlock)
+}
+func TestDAOContinueImplicitSupportTestnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, true, "", true, false, false, false, params.TestNetDAOForkBlock)
+}
+func TestDAOSwitchSupportTestnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, true, "", false, true, true, false, params.TestNetDAOForkBlock)
+}
+func TestDAOStartOpposeTestnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, true, "", false, false, false, true, nil)
+}
+func TestDAOContinueExplicitOpposeTestnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, true, "", false, false, true, true, nil)
+}
+func TestDAOContinueImplicitOpposeTestnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, true, "", false, false, true, false, nil)
+}
+func TestDAOSwitchOpposeTestnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, true, "", true, false, false, true, nil)
+}
+func TestDAODefaultPrivnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, false, daoNoForkGenesis, false, false, false, false, nil)
+}
+func TestDAOStartSupportConPrivnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, false, daoNoForkGenesis, false, true, false, false, params.MainNetDAOForkBlock)
+}
+func TestDAOContinueExplicitSupportConPrivnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, false, daoNoForkGenesis, true, true, false, false, params.MainNetDAOForkBlock)
+}
+func TestDAOContinueImplicitSupportConPrivnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, false, daoNoForkGenesis, true, false, false, false, params.MainNetDAOForkBlock)
+}
+func TestDAOSwitchSupportConPrivnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, false, daoNoForkGenesis, false, true, true, false, params.MainNetDAOForkBlock)
+}
+func TestDAOStartOpposeConPrivnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, false, daoNoForkGenesis, false, false, false, true, nil)
+}
+func TestDAOContinueExplicitOpposeConPrivnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, false, daoNoForkGenesis, false, false, true, true, nil)
+}
+func TestDAOContinueImplicitOpposeConPrivnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, false, daoNoForkGenesis, false, false, true, false, nil)
+}
+func TestDAOSwitchOpposeConPrivnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, false, daoNoForkGenesis, true, false, false, true, nil)
+}
+func TestDAODefaultProPrivnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, false, daoProForkGenesis, false, false, false, false, daoProForkBlock)
+}
+func TestDAOStartSupportProPrivnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, false, daoProForkGenesis, false, true, false, false, daoProForkBlock)
+}
+func TestDAOContinueExplicitSupportProPrivnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, false, daoProForkGenesis, true, true, false, false, daoProForkBlock)
+}
+func TestDAOContinueImplicitSupportProPrivnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, false, daoProForkGenesis, true, false, false, false, daoProForkBlock)
+}
+func TestDAOSwitchSupportProPrivnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, false, daoProForkGenesis, false, true, true, false, params.MainNetDAOForkBlock)
+}
+func TestDAOStartOpposeProPrivnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, false, daoProForkGenesis, false, false, false, true, nil)
+}
+func TestDAOContinueExplicitOpposeProPrivnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, false, daoProForkGenesis, false, false, true, true, nil)
+}
+func TestDAOContinueImplicitOpposeProPrivnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, false, daoProForkGenesis, false, false, true, false, nil)
+}
+func TestDAOSwitchOpposeProPrivnet(t *testing.T) {
+	testDAOForkBlockOldChain(t, false, daoProForkGenesis, true, false, false, true, nil)
+}
+
+func testDAOForkBlockOldChain(t *testing.T, testnet bool, genesis string, oldSupport, newSupport, oldOppose, newOppose bool, expect *big.Int) {
+	// Create a temporary data directory to use and inspect later
+	datadir := tmpdir(t)
+	defer os.RemoveAll(datadir)
+
+	// Cycle two Geth instances, possibly changing fork support in between
+	if genesis != "" {
+		json := filepath.Join(datadir, "genesis.json")
+		if err := ioutil.WriteFile(json, []byte(genesis), 0600); err != nil {
+			t.Fatalf("failed to write genesis file: %v", err)
+		}
+		runGeth(t, "--datadir", datadir, "init", json).cmd.Wait()
+	}
+	execDAOGeth(t, datadir, testnet, oldSupport, oldOppose)
+	execDAOGeth(t, datadir, testnet, newSupport, newOppose)
+
+	// Retrieve the DAO config flag from the database
+	path := filepath.Join(datadir, "chaindata")
+	if testnet {
+		path = filepath.Join(datadir, "testnet", "chaindata")
+	}
+	db, err := ethdb.NewLDBDatabase(path, 0, 0)
+	if err != nil {
+		t.Fatalf("failed to open test database: %v", err)
+	}
+	defer db.Close()
+
+	genesisHash := common.HexToHash("0xd4e56740f876aef8c010b86a40d5f56745a118d0906a34e69aec8c0db1cb8fa3")
+	if testnet {
+		genesisHash = common.HexToHash("0x0cd786a2425d16f152c658316c423e6ce1181e15c3295826d7c9904cba9ce303")
+	} else if genesis == daoNoForkGenesis {
+		genesisHash = daoNoForkGenesisHash
+	} else if genesis == daoProForkGenesis {
+		genesisHash = daoProForkGenesisHash
+	}
+	config, err := core.GetChainConfig(db, genesisHash)
+	if err != nil {
+		t.Fatalf("failed to retrieve chain config: %v", err)
+	}
+	// Validate the DAO hard-fork block number against the expected value
+	if config.DAOForkBlock == nil {
+		if expect != nil {
+			t.Fatalf("dao hard-fork block mismatch: have nil, want %v", expect)
+		}
+	} else if config.DAOForkBlock.Cmp(expect) != 0 {
+		t.Fatalf("dao hard-fork block mismatch: have %v, want %v", config.DAOForkBlock, expect)
+	}
+}
+
+// execDAOGeth starts a Geth instance with some DAO forks set and terminates.
+func execDAOGeth(t *testing.T, datadir string, testnet bool, supportFork bool, opposeFork bool) {
+	args := []string{"--port", "0", "--maxpeers", "0", "--nodiscover", "--nat", "none", "--ipcdisable", "--datadir", datadir}
+	if testnet {
+		args = append(args, "--testnet")
+	}
+	if supportFork {
+		args = append(args, "--support-dao-fork")
+	}
+	if opposeFork {
+		args = append(args, "--oppose-dao-fork")
+	}
+	geth := runGeth(t, append(args, []string{"--exec", "2+2", "console"}...)...)
+	geth.cmd.Wait()
+}
diff --git a/cmd/geth/main.go b/cmd/geth/main.go
index cb43f8769..5f1157b90 100644
--- a/cmd/geth/main.go
+++ b/cmd/geth/main.go
@@ -150,7 +150,6 @@ participating.
 		utils.IdentityFlag,
 		utils.UnlockedAccountFlag,
 		utils.PasswordFileFlag,
-		utils.GenesisFileFlag,
 		utils.BootnodesFlag,
 		utils.DataDirFlag,
 		utils.KeyStoreDirFlag,
@@ -165,6 +164,8 @@ participating.
 		utils.MaxPendingPeersFlag,
 		utils.EtherbaseFlag,
 		utils.GasPriceFlag,
+		utils.SupportDAOFork,
+		utils.OpposeDAOFork,
 		utils.MinerThreadsFlag,
 		utils.MiningEnabledFlag,
 		utils.MiningGPUFlag,
@@ -225,12 +226,6 @@ participating.
 		eth.EnableBadBlockReporting = true
 
 		utils.SetupNetwork(ctx)
-
-		// Deprecation warning.
-		if ctx.GlobalIsSet(utils.GenesisFileFlag.Name) {
-			common.PrintDepricationWarning("--genesis is deprecated. Switch to use 'geth init /path/to/file'")
-		}
-
 		return nil
 	}
 
diff --git a/cmd/geth/usage.go b/cmd/geth/usage.go
index e7ef9e2c7..eb897d2b5 100644
--- a/cmd/geth/usage.go
+++ b/cmd/geth/usage.go
@@ -68,7 +68,6 @@ var AppHelpFlagGroups = []flagGroup{
 			utils.OlympicFlag,
 			utils.TestNetFlag,
 			utils.DevModeFlag,
-			utils.GenesisFileFlag,
 			utils.IdentityFlag,
 			utils.FastSyncFlag,
 			utils.LightKDFFlag,
diff --git a/cmd/utils/flags.go b/cmd/utils/flags.go
index 38ba3a9ba..b95f5159c 100644
--- a/cmd/utils/flags.go
+++ b/cmd/utils/flags.go
@@ -126,10 +126,6 @@ var (
 		Name:  "dev",
 		Usage: "Developer mode: pre-configured private network with several debugging flags",
 	}
-	GenesisFileFlag = cli.StringFlag{
-		Name:  "genesis",
-		Usage: "Insert/overwrite the genesis block (JSON format)",
-	}
 	IdentityFlag = cli.StringFlag{
 		Name:  "identity",
 		Usage: "Custom node name",
@@ -161,6 +157,15 @@ var (
 		Name:  "lightkdf",
 		Usage: "Reduce key-derivation RAM & CPU usage at some expense of KDF strength",
 	}
+	// Fork settings
+	SupportDAOFork = cli.BoolFlag{
+		Name:  "support-dao-fork",
+		Usage: "Updates the chain rules to support the DAO hard-fork",
+	}
+	OpposeDAOFork = cli.BoolFlag{
+		Name:  "oppose-dao-fork",
+		Usage: "Updates the chain rules to oppose the DAO hard-fork",
+	}
 	// Miner settings
 	// TODO: refactor CPU vs GPU mining flags
 	MiningEnabledFlag = cli.BoolFlag{
@@ -534,20 +539,6 @@ func MakeWSRpcHost(ctx *cli.Context) string {
 	return ctx.GlobalString(WSListenAddrFlag.Name)
 }
 
-// MakeGenesisBlock loads up a genesis block from an input file specified in the
-// command line, or returns the empty string if none set.
-func MakeGenesisBlock(ctx *cli.Context) string {
-	genesis := ctx.GlobalString(GenesisFileFlag.Name)
-	if genesis == "" {
-		return ""
-	}
-	data, err := ioutil.ReadFile(genesis)
-	if err != nil {
-		Fatalf("Failed to load custom genesis file: %v", err)
-	}
-	return string(data)
-}
-
 // MakeDatabaseHandles raises out the number of allowed file handles per process
 // for Geth and returns half of the allowance to assign to the database.
 func MakeDatabaseHandles() int {
@@ -689,7 +680,6 @@ func MakeSystemNode(name, version string, relconf release.Config, extra []byte,
 
 	ethConf := &eth.Config{
 		ChainConfig:             MustMakeChainConfig(ctx),
-		Genesis:                 MakeGenesisBlock(ctx),
 		FastSync:                ctx.GlobalBool(FastSyncFlag.Name),
 		BlockChainVersion:       ctx.GlobalInt(BlockchainVersionFlag.Name),
 		DatabaseCache:           ctx.GlobalInt(CacheFlag.Name),
@@ -722,17 +712,13 @@ func MakeSystemNode(name, version string, relconf release.Config, extra []byte,
 		if !ctx.GlobalIsSet(NetworkIdFlag.Name) {
 			ethConf.NetworkId = 1
 		}
-		if !ctx.GlobalIsSet(GenesisFileFlag.Name) {
-			ethConf.Genesis = core.OlympicGenesisBlock()
-		}
+		ethConf.Genesis = core.OlympicGenesisBlock()
 
 	case ctx.GlobalBool(TestNetFlag.Name):
 		if !ctx.GlobalIsSet(NetworkIdFlag.Name) {
 			ethConf.NetworkId = 2
 		}
-		if !ctx.GlobalIsSet(GenesisFileFlag.Name) {
-			ethConf.Genesis = core.TestNetGenesisBlock()
-		}
+		ethConf.Genesis = core.TestNetGenesisBlock()
 		state.StartingNonce = 1048576 // (2**20)
 
 	case ctx.GlobalBool(DevModeFlag.Name):
@@ -747,9 +733,7 @@ func MakeSystemNode(name, version string, relconf release.Config, extra []byte,
 			stackConf.ListenAddr = ":0"
 		}
 		// Override the Ethereum protocol configs
-		if !ctx.GlobalIsSet(GenesisFileFlag.Name) {
-			ethConf.Genesis = core.OlympicGenesisBlock()
-		}
+		ethConf.Genesis = core.OlympicGenesisBlock()
 		if !ctx.GlobalIsSet(GasPriceFlag.Name) {
 			ethConf.GasPrice = new(big.Int)
 		}
@@ -813,24 +797,44 @@ func MustMakeChainConfig(ctx *cli.Context) *core.ChainConfig {
 
 // MustMakeChainConfigFromDb reads the chain configuration from the given database.
 func MustMakeChainConfigFromDb(ctx *cli.Context, db ethdb.Database) *core.ChainConfig {
-	genesis := core.GetBlock(db, core.GetCanonicalHash(db, 0), 0)
-
-	if genesis != nil {
-		// Existing genesis block, use stored config if available.
+	// If the chain is already initialized, use any existing chain configs
+	if genesis := core.GetBlock(db, core.GetCanonicalHash(db, 0), 0); genesis != nil {
 		storedConfig, err := core.GetChainConfig(db, genesis.Hash())
 		if err == nil {
+			// Force override any existing configs if explicitly requested
+			switch {
+			case storedConfig.DAOForkBlock == nil && ctx.GlobalBool(SupportDAOFork.Name) && ctx.GlobalBool(TestNetFlag.Name):
+				storedConfig.DAOForkBlock = params.TestNetDAOForkBlock
+			case storedConfig.DAOForkBlock == nil && ctx.GlobalBool(SupportDAOFork.Name):
+				storedConfig.DAOForkBlock = params.MainNetDAOForkBlock
+			case ctx.GlobalBool(OpposeDAOFork.Name):
+				storedConfig.DAOForkBlock = nil
+			}
 			return storedConfig
 		} else if err != core.ChainConfigNotFoundErr {
 			Fatalf("Could not make chain configuration: %v", err)
 		}
 	}
-	var homesteadBlockNo *big.Int
+	// If the chain is uninitialized nor no configs are present, create one
+	var homesteadBlock *big.Int
 	if ctx.GlobalBool(TestNetFlag.Name) {
-		homesteadBlockNo = params.TestNetHomesteadBlock
+		homesteadBlock = params.TestNetHomesteadBlock
 	} else {
-		homesteadBlockNo = params.MainNetHomesteadBlock
+		homesteadBlock = params.MainNetHomesteadBlock
+	}
+	var daoForkBlock *big.Int
+	switch {
+	case ctx.GlobalBool(SupportDAOFork.Name) && ctx.GlobalBool(TestNetFlag.Name):
+		daoForkBlock = params.TestNetDAOForkBlock
+	case ctx.GlobalBool(SupportDAOFork.Name):
+		daoForkBlock = params.MainNetDAOForkBlock
+	case ctx.GlobalBool(OpposeDAOFork.Name):
+		daoForkBlock = nil
+	}
+	return &core.ChainConfig{
+		HomesteadBlock: homesteadBlock,
+		DAOForkBlock:   daoForkBlock,
 	}
-	return &core.ChainConfig{HomesteadBlock: homesteadBlockNo}
 }
 
 // MakeChainDatabase open an LevelDB using the flags passed to the client and will hard crash if it fails.