cmd/utils: customize cli.HelpPrinter to fix alignment (#19956)

This copies cli.printHelp but changes minwidth to 38. Custom flag
code is improved to print the default value using cli.FlagStringer like
all built-in flags do.

cmd/utils/customflags.go

@@ -20,7 +20,6 @@ import (
 	"encoding"
 	"errors"
 	"flag"
-	"fmt"
 	"math/big"
 	"os"
 	"os/user"
@@ -34,33 +33,44 @@ import (
 // Custom type which is registered in the flags library which cli uses for
 // argument parsing. This allows us to expand Value to an absolute path when
 // the argument is parsed
-type DirectoryString struct {
-	Value string
-}
+type DirectoryString string
 
-func (self *DirectoryString) String() string {
-	return self.Value
+func (s *DirectoryString) String() string {
+	return string(*s)
 }
 
-func (self *DirectoryString) Set(value string) error {
-	self.Value = expandPath(value)
+func (s *DirectoryString) Set(value string) error {
+	*s = DirectoryString(expandPath(value))
 	return nil
 }
 
 // Custom cli.Flag type which expand the received string to an absolute path.
 // e.g. ~/.ethereum -> /home/username/.ethereum
 type DirectoryFlag struct {
-	Name  string
-	Value DirectoryString
-	Usage string
+	Name   string
+	Value  DirectoryString
+	Usage  string
+	EnvVar string
 }
 
-func (self DirectoryFlag) String() string {
-	fmtString := "%s %v\t%v"
-	if len(self.Value.Value) > 0 {
-		fmtString = "%s \"%v\"\t%v"
-	}
-	return fmt.Sprintf(fmtString, prefixedNames(self.Name), self.Value.Value, self.Usage)
+func (f DirectoryFlag) String() string {
+	return cli.FlagStringer(f)
+}
+
+// called by cli library, grabs variable from environment (if in env)
+// and adds variable to flag set for parsing.
+func (f DirectoryFlag) Apply(set *flag.FlagSet) {
+	eachName(f.Name, func(name string) {
+		set.Var(&f.Value, f.Name, f.Usage)
+	})
+}
+
+func (f DirectoryFlag) GetName() string {
+	return f.Name
+}
+
+func (f *DirectoryFlag) Set(value string) {
+	f.Value.Set(value)
 }
 
 func eachName(longName string, fn func(string)) {
@@ -71,14 +81,6 @@ func eachName(longName string, fn func(string)) {
 	}
 }
 
-// called by cli library, grabs variable from environment (if in env)
-// and adds variable to flag set for parsing.
-func (self DirectoryFlag) Apply(set *flag.FlagSet) {
-	eachName(self.Name, func(name string) {
-		set.Var(&self.Value, self.Name, self.Usage)
-	})
-}
-
 type TextMarshaler interface {
 	encoding.TextMarshaler
 	encoding.TextUnmarshaler
@@ -103,9 +105,10 @@ func (v textMarshalerVal) Set(s string) error {
 
 // TextMarshalerFlag wraps a TextMarshaler value.
 type TextMarshalerFlag struct {
-	Name  string
-	Value TextMarshaler
-	Usage string
+	Name   string
+	Value  TextMarshaler
+	Usage  string
+	EnvVar string
 }
 
 func (f TextMarshalerFlag) GetName() string {
@@ -113,7 +116,7 @@ func (f TextMarshalerFlag) GetName() string {
 }
 
 func (f TextMarshalerFlag) String() string {
-	return fmt.Sprintf("%s \"%v\"\t%v", prefixedNames(f.Name), f.Value, f.Usage)
+	return cli.FlagStringer(f)
 }
 
 func (f TextMarshalerFlag) Apply(set *flag.FlagSet) {
@@ -134,9 +137,10 @@ func GlobalTextMarshaler(ctx *cli.Context, name string) TextMarshaler {
 // BigFlag is a command line flag that accepts 256 bit big integers in decimal or
 // hexadecimal syntax.
 type BigFlag struct {
-	Name  string
-	Value *big.Int
-	Usage string
+	Name   string
+	Value  *big.Int
+	Usage  string
+	EnvVar string
 }
 
 // bigValue turns *big.Int into a flag.Value
@@ -163,11 +167,7 @@ func (f BigFlag) GetName() string {
 }
 
 func (f BigFlag) String() string {
-	fmtString := "%s %v\t%v"
-	if f.Value != nil {
-		fmtString = "%s \"%v\"\t%v"
-	}
-	return fmt.Sprintf(fmtString, prefixedNames(f.Name), f.Value, f.Usage)
+	return cli.FlagStringer(f)
 }
 
 func (f BigFlag) Apply(set *flag.FlagSet) {
@@ -207,14 +207,6 @@ func prefixedNames(fullName string) (prefixed string) {
 	return
 }
 
-func (self DirectoryFlag) GetName() string {
-	return self.Name
-}
-
-func (self *DirectoryFlag) Set(value string) {
-	self.Value.Value = value
-}
-
 // Expands a file path
 // 1. replace tilde with users home dir
 // 2. expands embedded environment variables

cmd/utils/flags.go

@@ -21,12 +21,15 @@ import (
 	"crypto/ecdsa"
 	"errors"
 	"fmt"
+	"io"
 	"io/ioutil"
 	"math/big"
 	"os"
 	"path/filepath"
 	"strconv"
 	"strings"
+	"text/tabwriter"
+	"text/template"
 	"time"
 
 	"github.com/ethereum/go-ethereum/accounts"
@@ -90,8 +93,8 @@ GLOBAL OPTIONS:
    {{range .Flags}}{{.}}
    {{end}}{{end}}
 `
-
 	cli.CommandHelpTemplate = CommandHelpTemplate
+	cli.HelpPrinter = printHelp
 }
 
 // NewApp creates an app with sane defaults.
@@ -105,6 +108,17 @@ func NewApp(gitCommit, gitDate, usage string) *cli.App {
 	return app
 }
 
+func printHelp(out io.Writer, templ string, data interface{}) {
+	funcMap := template.FuncMap{"join": strings.Join}
+	t := template.Must(template.New("help").Funcs(funcMap).Parse(templ))
+	w := tabwriter.NewWriter(out, 38, 8, 2, ' ', 0)
+	err := t.Execute(w, data)
+	if err != nil {
+		panic(err)
+	}
+	w.Flush()
+}
+
 // These are all the command line flags we support.
 // If you add to this list, please remember to include the
 // flag in the appropriate command definition.
@@ -117,7 +131,7 @@ var (
 	DataDirFlag = DirectoryFlag{
 		Name:  "datadir",
 		Usage: "Data directory for the databases and keystore",
-		Value: DirectoryString{node.DefaultDataDir()},
+		Value: DirectoryString(node.DefaultDataDir()),
 	}
 	AncientFlag = DirectoryFlag{
 		Name:  "datadir.ancient",
@@ -168,7 +182,7 @@ var (
 	DocRootFlag = DirectoryFlag{
 		Name:  "docroot",
 		Usage: "Document Root for HTTPClient file scheme",
-		Value: DirectoryString{homeDir()},
+		Value: DirectoryString(homeDir()),
 	}
 	ExitWhenSyncedFlag = cli.BoolFlag{
 		Name:  "exitwhensynced",
@@ -291,8 +305,8 @@ var (
 	}
 	EthashDatasetDirFlag = DirectoryFlag{
 		Name:  "ethash.dagdir",
-		Usage: "Directory to store the ethash mining DAGs (default = inside home folder)",
-		Value: DirectoryString{eth.DefaultConfig.Ethash.DatasetDir},
+		Usage: "Directory to store the ethash mining DAGs",
+		Value: DirectoryString(eth.DefaultConfig.Ethash.DatasetDir),
 	}
 	EthashDatasetsInMemoryFlag = cli.IntFlag{
 		Name:  "ethash.dagsinmem",