lnd+config: Move to FileExists function in lnrpc package

config.go

@@ -700,7 +700,7 @@ func LoadConfig(interceptor signal.Interceptor) (*Config, error) {
 	// User did specify an explicit --configfile, so we check that it does
 	// exist under that path to avoid surprises.
 	case configFilePath != DefaultConfigFile:
-		if !fileExists(configFilePath) {
+		if !lnrpc.FileExists(configFilePath) {
 			return nil, fmt.Errorf("specified config file does "+
 				"not exist in %s", configFilePath)
 		}

config_builder.go

@@ -466,9 +466,9 @@ func (d *DefaultWalletImpl) BuildWalletConfig(ctx context.Context,
 		// If the user requested a stateless initialization, no macaroon
 		// files should be created.
 		if !walletInitParams.StatelessInit &&
-			!fileExists(d.cfg.AdminMacPath) &&
+			!lnrpc.FileExists(d.cfg.AdminMacPath) &&
-			!fileExists(d.cfg.ReadMacPath) &&
+			!lnrpc.FileExists(d.cfg.ReadMacPath) &&
-			!fileExists(d.cfg.InvoiceMacPath) {
+			!lnrpc.FileExists(d.cfg.InvoiceMacPath) {
 
 			// Create macaroon files for lncli to use if they don't
 			// exist.
@@ -495,13 +495,13 @@ func (d *DefaultWalletImpl) BuildWalletConfig(ctx context.Context,
 				"--new_mac_root_key with --stateless_init to " +
 				"clean up and invalidate old macaroons."
 
-			if fileExists(d.cfg.AdminMacPath) {
+			if lnrpc.FileExists(d.cfg.AdminMacPath) {
 				d.logger.Warnf(msg, "admin", d.cfg.AdminMacPath)
 			}
-			if fileExists(d.cfg.ReadMacPath) {
+			if lnrpc.FileExists(d.cfg.ReadMacPath) {
 				d.logger.Warnf(msg, "readonly", d.cfg.ReadMacPath)
 			}
-			if fileExists(d.cfg.InvoiceMacPath) {
+			if lnrpc.FileExists(d.cfg.InvoiceMacPath) {
 				d.logger.Warnf(msg, "invoice", d.cfg.InvoiceMacPath)
 			}
 		}

tls_manager.go

@@ -210,7 +210,9 @@ func (t *TLSManager) generateOrRenewCert() (*tls.Config, func(), error) {
 // the encrypted form.
 func (t *TLSManager) generateCertPair(keyRing keychain.SecretKeyRing) error {
 	// Ensure we create TLS key and certificate if they don't exist.
-	if fileExists(t.cfg.TLSCertPath) || fileExists(t.cfg.TLSKeyPath) {
+	if lnrpc.FileExists(t.cfg.TLSCertPath) ||
+		lnrpc.FileExists(t.cfg.TLSKeyPath) {
+
 		// Handle discrepencies related to the TLSEncryptKey setting.
 		return t.ensureEncryption(keyRing)
 	}
@@ -597,18 +599,6 @@ func (t *TLSManager) deleteEphemeralSettings() {
 	t.ephemeralCertPath = ""
 }
 
-// fileExists reports whether the named file or directory exists.
-// This function is taken from https://github.com/btcsuite/btcd
-func fileExists(name string) bool {
-	if _, err := os.Stat(name); err != nil {
-		if os.IsNotExist(err) {
-			return false
-		}
-	}
-
-	return true
-}
-
 // IsCertExpired checks if the current TLS certificate is expired.
 func (t *TLSManager) IsCertExpired(keyRing keychain.SecretKeyRing) (bool,
 	time.Time, error) {