Quit when the specified configuration is file not found. (#273)

Also, error on an invalid rpc certificate.

cmd/dcrctl/config.go

@@ -215,7 +215,8 @@ func loadConfig() (*config, []string, error) {
 	parser := flags.NewParser(&cfg, flags.Default)
 	err = flags.NewIniParser(parser).ParseFile(preCfg.ConfigFile)
 	if err != nil {
-		if _, ok := err.(*os.PathError); !ok {
+		_, ok := err.(*os.PathError)
+		if !ok || preCfg.ConfigFile != cfg.ConfigFile {
 			fmt.Fprintf(os.Stderr, "Error parsing config file: %v\n",
 				err)
 			fmt.Fprintln(os.Stderr, usageMessage)

cmd/dcrctl/httpclient.go

@@ -44,7 +44,10 @@ func newHTTPClient(cfg *config) (*http.Client, error) {
 		}
 
 		pool := x509.NewCertPool()
-		pool.AppendCertsFromPEM(pem)
+		if ok := pool.AppendCertsFromPEM(pem); !ok {
+			return nil, fmt.Errorf("invalid certificate file: %v",
+				cfg.RPCCert)
+		}
 		tlsConfig = &tls.Config{
 			RootCAs:            pool,
 			InsecureSkipVerify: cfg.TLSSkipVerify,

config.go

@@ -412,20 +412,19 @@ func loadConfig() (*config, []string, error) {
 	}
 
 	// Load additional config from file.
-	var configFileError error
 	parser := newConfigParser(&cfg, &serviceOpts, flags.Default)
 	if !(preCfg.SimNet) || preCfg.ConfigFile !=
 		defaultConfigFile {
 
 		err := flags.NewIniParser(parser).ParseFile(preCfg.ConfigFile)
 		if err != nil {
-			if _, ok := err.(*os.PathError); !ok {
-				fmt.Fprintf(os.Stderr, "Error parsing config "+
-					"file: %v\n", err)
+			_, ok := err.(*os.PathError)
+			if !ok || preCfg.ConfigFile != defaultConfigFile {
+				fmt.Fprintf(os.Stderr, "Error parsing config file: %v\n",
+					err)
 				fmt.Fprintln(os.Stderr, usageMessage)
 				return nil, nil, err
 			}
-			configFileError = err
 		}
 	}
 
@@ -868,13 +867,6 @@ func loadConfig() (*config, []string, error) {
 		}
 	}
 
-	// Warn about missing config file only after all other configuration is
-	// done.  This prevents the warning on help messages and invalid
-	// options.  Note this should go directly before the return.
-	if configFileError != nil {
-		dcrdLog.Warnf("%v", configFileError)
-	}
-
 	return &cfg, remainingArgs, nil
 }