Read RPC username/pass from correct config file for btcctl defaults.

If no existing btcctl.conf file exists, btcctl creates a default one
using the RPC username and password from the btcd.conf. If the
--wallet flag is passed, however, it should read from btcwallet.conf
instead.

btcsuite#875.

cmd/btcctl/config.go

@@ -211,7 +211,15 @@ func loadConfig() (*config, []string, error) {
 	}
 
 	if _, err := os.Stat(preCfg.ConfigFile); os.IsNotExist(err) {
-		err := createDefaultConfigFile(preCfg.ConfigFile)
+		// Use config file for RPC server to create default btcctl config
+		var serverConfigPath string
+		if preCfg.Wallet {
+			serverConfigPath = filepath.Join(btcwalletHomeDir, "btcwallet.conf")
+		} else {
+			serverConfigPath = filepath.Join(btcdHomeDir, "btcd.conf")
+		}
+
+		err := createDefaultConfigFile(preCfg.ConfigFile, serverConfigPath)
 		if err != nil {
 			fmt.Fprintf(os.Stderr, "Error creating a default config file: %v\n", err)
 		}
@@ -272,17 +280,16 @@ func loadConfig() (*config, []string, error) {
 }
 
 // createDefaultConfig creates a basic config file at the given destination path.
-// For this it tries to read the btcd config file at its default path, and extract
-// the RPC user and password from it.
-func createDefaultConfigFile(destinationPath string) error {
-	// Read btcd.conf from its default path
-	btcdConfigPath := filepath.Join(btcdHomeDir, "btcd.conf")
-	btcdConfigFile, err := os.Open(btcdConfigPath)
+// For this it tries to read the config file for the RPC server (either btcd or
+// btcwallet), and extract the RPC user and password from it.
+func createDefaultConfigFile(destinationPath, serverConfigPath string) error {
+	// Read the RPC server config
+	serverConfigFile, err := os.Open(serverConfigPath)
 	if err != nil {
 		return err
 	}
-	defer btcdConfigFile.Close()
-	content, err := ioutil.ReadAll(btcdConfigFile)
+	defer serverConfigFile.Close()
+	content, err := ioutil.ReadAll(serverConfigFile)
 	if err != nil {
 		return err
 	}