Code maintenance: CLI interface abstraction

internal/cli/clientkey.go

@@ -0,0 +1,41 @@
+package cli
+
+import (
+	"flag"
+	"fmt"
+	"io/ioutil"
+	"strings"
+
+	"github.com/qdm12/gluetun/internal/constants"
+	"github.com/qdm12/gluetun/internal/os"
+)
+
+func (c *cli) ClientKey(args []string, openFile os.OpenFileFunc) error {
+	flagSet := flag.NewFlagSet("clientkey", flag.ExitOnError)
+	filepath := flagSet.String("path", string(constants.ClientKey), "file path to the client.key file")
+	if err := flagSet.Parse(args); err != nil {
+		return err
+	}
+	file, err := openFile(*filepath, os.O_RDONLY, 0)
+	if err != nil {
+		return err
+	}
+	data, err := ioutil.ReadAll(file)
+	if err != nil {
+		_ = file.Close()
+		return err
+	}
+	if err := file.Close(); err != nil {
+		return err
+	}
+	if err != nil {
+		return err
+	}
+	s := string(data)
+	s = strings.ReplaceAll(s, "\n", "")
+	s = strings.ReplaceAll(s, "\r", "")
+	s = strings.TrimPrefix(s, "-----BEGIN PRIVATE KEY-----")
+	s = strings.TrimSuffix(s, "-----END PRIVATE KEY-----")
+	fmt.Println(s)
+	return nil
+}