cmd/geth: add --syncmode

cmd/geth/main.go

@@ -96,6 +96,7 @@ func init() {
 		utils.EthashDatasetsOnDiskFlag,
 		utils.FastSyncFlag,
 		utils.LightModeFlag,
+		utils.SyncModeFlag,
 		utils.LightServFlag,
 		utils.LightPeersFlag,
 		utils.LightKDFFlag,

cmd/utils/customflags.go

@@ -17,6 +17,7 @@
 package utils
 
 import (
+	"encoding"
 	"errors"
 	"flag"
 	"fmt"
@@ -78,6 +79,58 @@ func (self DirectoryFlag) Apply(set *flag.FlagSet) {
 	})
 }
 
+type TextMarshaler interface {
+	encoding.TextMarshaler
+	encoding.TextUnmarshaler
+}
+
+// textMarshalerVal turns a TextMarshaler into a flag.Value
+type textMarshalerVal struct {
+	v TextMarshaler
+}
+
+func (v textMarshalerVal) String() string {
+	if v.v == nil {
+		return ""
+	}
+	text, _ := v.v.MarshalText()
+	return string(text)
+}
+
+func (v textMarshalerVal) Set(s string) error {
+	return v.v.UnmarshalText([]byte(s))
+}
+
+// TextMarshalerFlag wraps a TextMarshaler value.
+type TextMarshalerFlag struct {
+	Name  string
+	Value TextMarshaler
+	Usage string
+}
+
+func (f TextMarshalerFlag) GetName() string {
+	return f.Name
+}
+
+func (f TextMarshalerFlag) String() string {
+	return fmt.Sprintf("%s \"%v\"\t%v", prefixedNames(f.Name), f.Value, f.Usage)
+}
+
+func (f TextMarshalerFlag) Apply(set *flag.FlagSet) {
+	eachName(f.Name, func(name string) {
+		set.Var(textMarshalerVal{f.Value}, f.Name, f.Usage)
+	})
+}
+
+// GlobalTextMarshaler returns the value of a TextMarshalerFlag from the global flag set.
+func GlobalTextMarshaler(ctx *cli.Context, name string) TextMarshaler {
+	val := ctx.GlobalGeneric(name)
+	if val == nil {
+		return nil
+	}
+	return val.(textMarshalerVal).v
+}
+
 // BigFlag is a command line flag that accepts 256 bit big integers in decimal or
 // hexadecimal syntax.
 type BigFlag struct {

cmd/utils/flags.go

@@ -174,6 +174,13 @@ var (
 		Name:  "light",
 		Usage: "Enable light client mode",
 	}
+	defaultSyncMode = eth.DefaultConfig.SyncMode
+	SyncModeFlag    = TextMarshalerFlag{
+		Name:  "syncmode",
+		Usage: `Blockchain sync mode ("fast", "full", or "light")`,
+		Value: &defaultSyncMode,
+	}
+
 	LightServFlag = cli.IntFlag{
 		Name:  "lightserv",
 		Usage: "Maximum percentage of time allowed for serving LES requests (0-90)",
@@ -760,11 +767,11 @@ func setEthash(ctx *cli.Context, cfg *eth.Config) {
 	}
 }
 
-func checkExclusive(ctx *cli.Context, flags ...cli.BoolFlag) {
+func checkExclusive(ctx *cli.Context, flags ...cli.Flag) {
 	set := make([]string, 0, 1)
 	for _, flag := range flags {
-		if ctx.GlobalIsSet(flag.Name) {
-			set = append(set, "--"+flag.Name)
+		if ctx.GlobalIsSet(flag.GetName()) {
+			set = append(set, "--"+flag.GetName())
 		}
 	}
 	if len(set) > 1 {
@@ -776,16 +783,19 @@ func checkExclusive(ctx *cli.Context, flags ...cli.BoolFlag) {
 func SetEthConfig(ctx *cli.Context, stack *node.Node, cfg *eth.Config) {
 	// Avoid conflicting network flags
 	checkExclusive(ctx, DevModeFlag, TestNetFlag)
-	checkExclusive(ctx, FastSyncFlag, LightModeFlag)
+	checkExclusive(ctx, FastSyncFlag, LightModeFlag, SyncModeFlag)
 
 	ks := stack.AccountManager().Backends(keystore.KeyStoreType)[0].(*keystore.KeyStore)
 	setEtherbase(ctx, ks, cfg)
 	setGPO(ctx, &cfg.GPO)
 	setEthash(ctx, cfg)
 
-	if ctx.GlobalBool(FastSyncFlag.Name) {
+	switch {
+	case ctx.GlobalIsSet(SyncModeFlag.Name):
+		cfg.SyncMode = *GlobalTextMarshaler(ctx, SyncModeFlag.Name).(*downloader.SyncMode)
+	case ctx.GlobalBool(FastSyncFlag.Name):
 		cfg.SyncMode = downloader.FastSync
-	} else if ctx.GlobalBool(LightModeFlag.Name) {
+	case ctx.GlobalBool(LightModeFlag.Name):
 		cfg.SyncMode = downloader.LightSync
 	}
 	if ctx.GlobalIsSet(LightServFlag.Name) {