Handle flags explicitly set to defaults.

This prevents treating a flag that was explicitly set to the default
as unchanged, since the explicit set is recorded in the new
*cfgutil.ExplicitString flag type.

btcwallet.go

@@ -61,7 +61,7 @@ func walletMain() error {
 		}()
 	}
 
-	dbDir := networkDir(cfg.AppDataDir, activeNet.Params)
+	dbDir := networkDir(cfg.AppDataDir.Value, activeNet.Params)
 	loader := wallet.NewLoader(activeNet.Params, dbDir)
 
 	// Create and start HTTP server to serve wallet client connections.
@@ -197,7 +197,7 @@ func readCAFile() []byte {
 	var certs []byte
 	if !cfg.DisableClientTLS {
 		var err error
-		certs, err = ioutil.ReadFile(cfg.CAFile)
+		certs, err = ioutil.ReadFile(cfg.CAFile.Value)
 		if err != nil {
 			log.Warnf("Cannot open CA file: %v", err)
 			// If there's an error reading the CA file, continue

config.go

@@ -45,11 +45,11 @@ var (
 
 type config struct {
 	// General application behavior
-	ConfigFile    string `short:"C" long:"configfile" description:"Path to configuration file"`
+	ConfigFile    *cfgutil.ExplicitString `short:"C" long:"configfile" description:"Path to configuration file"`
 	ShowVersion   bool                    `short:"V" long:"version" description:"Display version information and exit"`
 	Create        bool                    `long:"create" description:"Create the wallet if it does not exist"`
 	CreateTemp    bool                    `long:"createtemp" description:"Create a temporary simulation wallet (pass=password) in the data directory indicated; must call with --datadir"`
-	AppDataDir    string `short:"A" long:"appdata" description:"Application data directory for wallet config, databases and logs"`
+	AppDataDir    *cfgutil.ExplicitString `short:"A" long:"appdata" description:"Application data directory for wallet config, databases and logs"`
 	TestNet3      bool                    `long:"testnet" description:"Use the test Bitcoin network (version 3) (default mainnet)"`
 	SimNet        bool                    `long:"simnet" description:"Use the simulation test network (default mainnet)"`
 	NoInitialLoad bool                    `long:"noinitialload" description:"Defer wallet creation/opening on startup and enable loading wallets over RPC"`
@@ -62,7 +62,7 @@ type config struct {
 
 	// RPC client options
 	RPCConnect       string                  `short:"c" long:"rpcconnect" description:"Hostname/IP and port of btcd RPC server to connect to (default localhost:8334, testnet: localhost:18334, simnet: localhost:18556)"`
-	CAFile           string `long:"cafile" description:"File containing root certificates to authenticate a TLS connections with btcd"`
+	CAFile           *cfgutil.ExplicitString `long:"cafile" description:"File containing root certificates to authenticate a TLS connections with btcd"`
 	DisableClientTLS bool                    `long:"noclienttls" description:"Disable TLS for the RPC client -- NOTE: This is only allowed if the RPC client is connecting to localhost"`
 	BtcdUsername     string                  `long:"btcdusername" description:"Username for btcd authentication"`
 	BtcdPassword     string                  `long:"btcdpassword" default-mask:"-" description:"Password for btcd authentication"`
@@ -78,8 +78,8 @@ type config struct {
 	//
 	// Usernames can also be used for the consensus RPC client, so they
 	// aren't considered legacy.
-	RPCCert                string   `long:"rpccert" description:"File containing the certificate file"`
+	RPCCert                *cfgutil.ExplicitString `long:"rpccert" description:"File containing the certificate file"`
-	RPCKey                 string   `long:"rpckey" description:"File containing the certificate key"`
+	RPCKey                 *cfgutil.ExplicitString `long:"rpckey" description:"File containing the certificate key"`
 	OneTimeTLSKey          bool                    `long:"onetimetlskey" description:"Generate a new TLS certpair at startup, but only write the certificate to disk"`
 	DisableServerTLS       bool                    `long:"noservertls" description:"Disable TLS for the RPC server -- NOTE: This is only allowed if the RPC server is bound to localhost"`
 	LegacyRPCListeners     []string                `long:"rpclisten" description:"Listen for legacy RPC connections on this interface/port (default port: 8332, testnet: 18332, simnet: 18554)"`
@@ -95,7 +95,7 @@ type config struct {
 	ExperimentalRPCListeners []string `long:"experimentalrpclisten" description:"Listen for RPC connections on this interface/port"`
 
 	// Deprecated options
-	DataDir string `short:"b" long:"datadir" default-mask:"-" description:"DEPRECATED -- use appdata instead"`
+	DataDir *cfgutil.ExplicitString `short:"b" long:"datadir" default-mask:"-" description:"DEPRECATED -- use appdata instead"`
 }
 
 // cleanAndExpandPath expands environement variables and leading ~ in the
@@ -247,15 +247,16 @@ func loadConfig() (*config, []string, error) {
 	// Default config.
 	cfg := config{
 		DebugLevel:             defaultLogLevel,
-		ConfigFile:             defaultConfigFile,
+		ConfigFile:             cfgutil.NewExplicitString(defaultConfigFile),
-		AppDataDir:             defaultAppDataDir,
+		AppDataDir:             cfgutil.NewExplicitString(defaultAppDataDir),
 		LogDir:                 defaultLogDir,
 		WalletPass:             wallet.InsecurePubPassphrase,
-		RPCKey:                 defaultRPCKeyFile,
+		CAFile:                 cfgutil.NewExplicitString(""),
-		RPCCert:                defaultRPCCertFile,
+		RPCKey:                 cfgutil.NewExplicitString(defaultRPCKeyFile),
+		RPCCert:                cfgutil.NewExplicitString(defaultRPCCertFile),
 		LegacyRPCMaxClients:    defaultRPCMaxClients,
 		LegacyRPCMaxWebsockets: defaultRPCMaxWebsockets,
-		DataDir:                defaultAppDataDir,
+		DataDir:                cfgutil.NewExplicitString(defaultAppDataDir),
 	}
 
 	// Pre-parse the command line options to see if an alternative config
@@ -283,17 +284,17 @@ func loadConfig() (*config, []string, error) {
 	// Load additional config from file.
 	var configFileError error
 	parser := flags.NewParser(&cfg, flags.Default)
-	configFilePath := preCfg.ConfigFile
+	configFilePath := preCfg.ConfigFile.Value
-	if configFilePath == defaultConfigFile {
+	if preCfg.ConfigFile.ExplicitlySet() {
-		appDataDir := preCfg.AppDataDir
+		configFilePath = cleanAndExpandPath(configFilePath)
-		if appDataDir == defaultAppDataDir && preCfg.DataDir != defaultAppDataDir {
+	} else {
-			appDataDir = cleanAndExpandPath(preCfg.DataDir)
+		appDataDir := preCfg.AppDataDir.Value
+		if !preCfg.AppDataDir.ExplicitlySet() && preCfg.DataDir.ExplicitlySet() {
+			appDataDir = cleanAndExpandPath(preCfg.DataDir.Value)
 		}
 		if appDataDir != defaultAppDataDir {
 			configFilePath = filepath.Join(appDataDir, defaultConfigFilename)
 		}
-	} else {
-		configFilePath = cleanAndExpandPath(configFilePath)
 	}
 	err = flags.NewIniParser(parser).ParseFile(configFilePath)
 	if err != nil {
@@ -323,24 +324,24 @@ func loadConfig() (*config, []string, error) {
 
 	// Check deprecated aliases.  The new options receive priority when both
 	// are changed from the default.
-	if cfg.DataDir != defaultAppDataDir {
+	if cfg.DataDir.ExplicitlySet() {
 		fmt.Fprintln(os.Stderr, "datadir option has been replaced by "+
 			"appdata -- please update your config")
-		if cfg.AppDataDir == defaultAppDataDir {
+		if !cfg.AppDataDir.ExplicitlySet() {
-			cfg.AppDataDir = cfg.DataDir
+			cfg.AppDataDir.Value = cfg.DataDir.Value
 		}
 	}
 
 	// If an alternate data directory was specified, and paths with defaults
 	// relative to the data dir are unchanged, modify each path to be
 	// relative to the new data dir.
-	if cfg.AppDataDir != defaultAppDataDir {
+	if cfg.AppDataDir.ExplicitlySet() {
-		cfg.AppDataDir = cleanAndExpandPath(cfg.AppDataDir)
+		cfg.AppDataDir.Value = cleanAndExpandPath(cfg.AppDataDir.Value)
-		if cfg.RPCKey == defaultRPCKeyFile {
+		if !cfg.RPCKey.ExplicitlySet() {
-			cfg.RPCKey = filepath.Join(cfg.AppDataDir, "rpc.key")
+			cfg.RPCKey.Value = filepath.Join(cfg.AppDataDir.Value, "rpc.key")
 		}
-		if cfg.RPCCert == defaultRPCCertFile {
+		if !cfg.RPCCert.ExplicitlySet() {
-			cfg.RPCCert = filepath.Join(cfg.AppDataDir, "rpc.cert")
+			cfg.RPCCert.Value = filepath.Join(cfg.AppDataDir.Value, "rpc.cert")
 		}
 	}
 
@@ -389,7 +390,7 @@ func loadConfig() (*config, []string, error) {
 
 	// Exit if you try to use a simulation wallet with a standard
 	// data directory.
-	if cfg.AppDataDir == defaultAppDataDir && cfg.CreateTemp {
+	if (!cfg.AppDataDir.ExplicitlySet() || !cfg.DataDir.ExplicitlySet()) && cfg.CreateTemp {
 		fmt.Fprintln(os.Stderr, "Tried to create a temporary simulation "+
 			"wallet, but failed to specify data directory!")
 		os.Exit(0)
@@ -404,7 +405,7 @@ func loadConfig() (*config, []string, error) {
 	}
 
 	// Ensure the wallet exists or create it when the create flag is set.
-	netDir := networkDir(cfg.AppDataDir, activeNet.Params)
+	netDir := networkDir(cfg.AppDataDir.Value, activeNet.Params)
 	dbPath := filepath.Join(netDir, walletDbName)
 
 	if cfg.CreateTemp && cfg.Create {
@@ -519,12 +520,12 @@ func loadConfig() (*config, []string, error) {
 		}
 	} else {
 		// If CAFile is unset, choose either the copy or local btcd cert.
-		if cfg.CAFile == "" {
+		if !cfg.CAFile.ExplicitlySet() {
-			cfg.CAFile = filepath.Join(cfg.AppDataDir, defaultCAFilename)
+			cfg.CAFile.Value = filepath.Join(cfg.AppDataDir.Value, defaultCAFilename)
 
 			// If the CA copy does not exist, check if we're connecting to
 			// a local btcd and switch to its RPC cert if it exists.
-			certExists, err := cfgutil.FileExists(cfg.CAFile)
+			certExists, err := cfgutil.FileExists(cfg.CAFile.Value)
 			if err != nil {
 				fmt.Fprintln(os.Stderr, err)
 				return nil, nil, err
@@ -538,7 +539,7 @@ func loadConfig() (*config, []string, error) {
 						return nil, nil, err
 					}
 					if btcdCertExists {
-						cfg.CAFile = btcdDefaultCAFile
+						cfg.CAFile.Value = btcdDefaultCAFile
 					}
 				}
 			}
@@ -625,9 +626,9 @@ func loadConfig() (*config, []string, error) {
 	}
 
 	// Expand environment variable and leading ~ for filepaths.
-	cfg.CAFile = cleanAndExpandPath(cfg.CAFile)
+	cfg.CAFile.Value = cleanAndExpandPath(cfg.CAFile.Value)
-	cfg.RPCCert = cleanAndExpandPath(cfg.RPCCert)
+	cfg.RPCCert.Value = cleanAndExpandPath(cfg.RPCCert.Value)
-	cfg.RPCKey = cleanAndExpandPath(cfg.RPCKey)
+	cfg.RPCKey.Value = cleanAndExpandPath(cfg.RPCKey.Value)
 
 	// If the btcd username or password are unset, use the same auth as for
 	// the client.  The two settings were previously shared for btcd and

internal/cfgutil/explicitflags.go

@@ -0,0 +1,36 @@
+// Copyright (c) 2016 The btcsuite developers
+// Use of this source code is governed by an ISC
+// license that can be found in the LICENSE file.
+
+package cfgutil
+
+// ExplicitString is a string value implementing the flags.Marshaler and
+// flags.Unmarshaler interfaces so it may be used as a config struct field.  It
+// records whether the value was explicitly set by the flags package.  This is
+// useful when behavior must be modified depending on whether a flag was set by
+// the user or left as a default.  Without recording this, it would be
+// impossible to determine whether flag with a default value was unmodified or
+// explicitly set to the default.
+type ExplicitString struct {
+	Value         string
+	explicitlySet bool
+}
+
+// NewExplicitString creates a string flag with the provided default value.
+func NewExplicitString(defaultValue string) *ExplicitString {
+	return &ExplicitString{Value: defaultValue, explicitlySet: false}
+}
+
+// ExplicitlySet returns whether the flag was explicitly set through the
+// flags.Unmarshaler interface.
+func (e *ExplicitString) ExplicitlySet() bool { return e.explicitlySet }
+
+// MarshalFlag implements the flags.Marshaler interface.
+func (e *ExplicitString) MarshalFlag() (string, error) { return e.Value, nil }
+
+// UnmarshalFlag implements the flags.Unmarshaler interface.
+func (e *ExplicitString) UnmarshalFlag(value string) error {
+	e.Value = value
+	e.explicitlySet = true
+	return nil
+}

rpcserver.go

@@ -35,19 +35,19 @@ func openRPCKeyPair() (tls.Certificate, error) {
 	// acceptable if the previous execution used a one time TLS key.
 	// Otherwise, both the cert and key should be read from disk.  If the
 	// cert is missing, the read error will occur in LoadX509KeyPair.
-	_, e := os.Stat(cfg.RPCKey)
+	_, e := os.Stat(cfg.RPCKey.Value)
 	keyExists := !os.IsNotExist(e)
 	switch {
 	case cfg.OneTimeTLSKey && keyExists:
 		err := fmt.Errorf("one time TLS keys are enabled, but TLS key "+
-			"`%s` already exists", cfg.RPCKey)
+			"`%s` already exists", cfg.RPCKey.Value)
 		return tls.Certificate{}, err
 	case cfg.OneTimeTLSKey:
 		return generateRPCKeyPair(false)
 	case !keyExists:
 		return generateRPCKeyPair(true)
 	default:
-		return tls.LoadX509KeyPair(cfg.RPCCert, cfg.RPCKey)
+		return tls.LoadX509KeyPair(cfg.RPCCert.Value, cfg.RPCKey.Value)
 	}
 }
 
@@ -58,8 +58,8 @@ func generateRPCKeyPair(writeKey bool) (tls.Certificate, error) {
 	log.Infof("Generating TLS certificates...")
 
 	// Create directories for cert and key files if they do not yet exist.
-	certDir, _ := filepath.Split(cfg.RPCCert)
+	certDir, _ := filepath.Split(cfg.RPCCert.Value)
-	keyDir, _ := filepath.Split(cfg.RPCKey)
+	keyDir, _ := filepath.Split(cfg.RPCKey.Value)
 	err := os.MkdirAll(certDir, 0700)
 	if err != nil {
 		return tls.Certificate{}, err
@@ -82,14 +82,14 @@ func generateRPCKeyPair(writeKey bool) (tls.Certificate, error) {
 	}
 
 	// Write cert and (potentially) the key files.
-	err = ioutil.WriteFile(cfg.RPCCert, cert, 0600)
+	err = ioutil.WriteFile(cfg.RPCCert.Value, cert, 0600)
 	if err != nil {
 		return tls.Certificate{}, err
 	}
 	if writeKey {
-		err = ioutil.WriteFile(cfg.RPCKey, key, 0600)
+		err = ioutil.WriteFile(cfg.RPCKey.Value, key, 0600)
 		if err != nil {
-			rmErr := os.Remove(cfg.RPCCert)
+			rmErr := os.Remove(cfg.RPCCert.Value)
 			if rmErr != nil {
 				log.Warnf("Cannot remove written certificates: %v",
 					rmErr)

walletsetup.go

@@ -99,13 +99,13 @@ func convertLegacyKeystore(legacyKeyStore *keystore.Store, manager *waddrmgr.Man
 // and generates the wallet accordingly.  The new wallet will reside at the
 // provided path.
 func createWallet(cfg *config) error {
-	dbDir := networkDir(cfg.AppDataDir, activeNet.Params)
+	dbDir := networkDir(cfg.AppDataDir.Value, activeNet.Params)
 	loader := wallet.NewLoader(activeNet.Params, dbDir)
 
 	// When there is a legacy keystore, open it now to ensure any errors
 	// don't end up exiting the process after the user has spent time
 	// entering a bunch of information.
-	netDir := networkDir(cfg.AppDataDir, activeNet.Params)
+	netDir := networkDir(cfg.AppDataDir.Value, activeNet.Params)
 	keystorePath := filepath.Join(netDir, keystore.Filename)
 	var legacyKeyStore *keystore.Store
 	_, err := os.Stat(keystorePath)
@@ -207,7 +207,7 @@ func createSimulationWallet(cfg *config) error {
 	// Public passphrase is the default.
 	pubPass := []byte(wallet.InsecurePubPassphrase)
 
-	netDir := networkDir(cfg.AppDataDir, activeNet.Params)
+	netDir := networkDir(cfg.AppDataDir.Value, activeNet.Params)
 
 	// Create the wallet.
 	dbPath := filepath.Join(netDir, walletDbName)