Remove static target for decrypt util

Signed-off-by: Knut Ahlers <knut@ahlers.me>

cmd/sii-decrypt/main.go

@@ -8,12 +8,15 @@ import (
 
 	"github.com/Luzifer/rconfig/v2"
 	"github.com/Luzifer/sii"
+	"github.com/pkg/errors"
 	log "github.com/sirupsen/logrus"
 )
 
 var (
 	cfg = struct {
+		Backup         bool   `flag:"backup,b" default:"true" description:"Bakcup encrypted file when in-place mode is used"`
 		DecryptKey     string `flag:"decrypt-key" default:"" description:"Hex formated decryption key" validate:"nonzero"`
+		InPlace        bool   `flag:"in-place,i" default:"false" description:"Write the decrypted version to the same file the encrypted version was read from"`
 		LogLevel       string `flag:"log-level" default:"info" description:"Log level (debug, info, warn, error, fatal)"`
 		VersionAndExit bool   `flag:"version" default:"false" description:"Prints current version and exits"`
 	}{}
@@ -51,12 +54,14 @@ func main() {
 		log.Fatal("Expecting exactly one SII file as an argument")
 	}
 
-	stat, err := os.Stat(rconfig.Args()[1])
+	var filename = rconfig.Args()[1]
+
+	stat, err := os.Stat(filename)
 	if err != nil {
 		log.WithError(err).Fatal("Unable to read info of save-file")
 	}
 
-	f, err := os.Open(rconfig.Args()[1])
+	f, err := os.Open(filename)
 	if err != nil {
 		log.WithError(err).Fatal("Unable to open encrypted file")
 	}
@@ -69,13 +74,45 @@ func main() {
 		log.WithError(err).Fatal("Unable to decrypt file")
 	}
 
-	tf, err := os.Create("/tmp/output")
+	var output io.Writer = os.Stdout
-	if err != nil {
-		log.WithError(err).Fatal("Unable to create output file")
-	}
-	defer tf.Close()
 
-	if _, err := io.Copy(tf, contentReader); err != nil {
+	if cfg.InPlace {
+		if cfg.Backup {
+			if err := copyFile(filename, filename+".bak"); err != nil {
+				log.WithError(err).Fatal("Unable to create file backup")
+			}
+		}
+
+		// Close input file right now as we need to re-create it
+		f.Close()
+
+		tf, err := os.Create(filename)
+		if err != nil {
+			log.WithError(err).Fatal("Unable to create output file")
+		}
+		defer tf.Close()
+
+		output = tf
+	}
+
+	if _, err := io.Copy(output, contentReader); err != nil {
 		log.WithError(err).Fatal("Unable to copy content")
 	}
 }
+
+func copyFile(src, dst string) error {
+	s, err := os.Open(src)
+	if err != nil {
+		return errors.Wrap(err, "Unable to open source file")
+	}
+	defer s.Close()
+
+	d, err := os.Create(dst)
+	if err != nil {
+		return errors.Wrap(err, "Unable to open dest file")
+	}
+	defer d.Close()
+
+	_, err = io.Copy(d, s)
+	return err
+}