Allow multiple retries for interactive password input

Restic used to quit if the repository password was typed incorrectly once.
Restic will now ask the user again for the repository password if typed incorrectly.
The user will now get three tries to input the correct password before restic quits.

changelog/unreleased/issue-2306

@@ -0,0 +1,7 @@
+Enhancement: Allow multiple retries for interactive password input
+
+Restic used to quit if the repository password was typed incorrectly once.
+Restic will now ask the user again for the repository password if typed incorrectly.
+The user will now get three tries to input the correct password before restic quits. 
+
+https://github.com/restic/restic/issues/2306

cmd/restic/global.go

@@ -319,7 +319,7 @@ func ReadPassword(opts GlobalOptions, prompt string) (string, error) {
 	}
 
 	if len(password) == 0 {
-		return "", errors.Fatal("an empty password is not a password")
+		return "", errors.New("an empty password is not a password")
 	}
 
 	return password, nil
@@ -365,14 +365,32 @@ func OpenRepository(opts GlobalOptions) (*repository.Repository, error) {
 
 	s := repository.New(be)
 
-	opts.password, err = ReadPassword(opts, "enter password for repository: ")
-	if err != nil {
-		return nil, err
+	passwordTriesLeft := 1
+	if stdinIsTerminal() && opts.password == "" {
+		passwordTriesLeft = 3
 	}
 
-	err = s.SearchKey(opts.ctx, opts.password, maxKeys, opts.KeyHint)
+	for ; passwordTriesLeft > 0; passwordTriesLeft-- {
+		opts.password, err = ReadPassword(opts, "enter password for repository: ")
+		if err != nil && passwordTriesLeft > 1 {
+			opts.password = ""
+			fmt.Printf("%s. Try again\n", err)
+		}
+		if err != nil {
+			continue
+		}
+
+		err = s.SearchKey(opts.ctx, opts.password, maxKeys, opts.KeyHint)
+		if err != nil && passwordTriesLeft > 1 {
+			opts.password = ""
+			fmt.Printf("%s. Try again\n", err)
+		}
+	}
 	if err != nil {
-		return nil, err
+		if errors.IsFatal(err) {
+			return nil, err
+		}
+		return nil, errors.Fatalf("%s", err)
 	}
 
 	if stdoutIsTerminal() && !opts.JSON {

internal/repository/key.go

@@ -18,7 +18,7 @@ import (
 
 var (
 	// ErrNoKeyFound is returned when no key for the repository could be decrypted.
-	ErrNoKeyFound = errors.Fatal("wrong password or no key found")
+	ErrNoKeyFound = errors.New("wrong password or no key found")
 
 	// ErrMaxKeysReached is returned when the maximum number of keys was checked and no key could be found.
 	ErrMaxKeysReached = errors.Fatal("maximum number of keys reached")