ui/backup: Quote funny filenames

Fixes #4191.

internal/ui/backup/text.go

@@ -3,7 +3,9 @@ package backup
 import (
 	"fmt"
 	"sort"
+	"strconv"
 	"time"
+	"unicode"
 
 	"github.com/restic/restic/internal/archiver"
 	"github.com/restic/restic/internal/restic"
@@ -86,6 +88,8 @@ func (b *TextProgress) Error(item string, err error) error {
 // CompleteItem is the status callback function for the archiver when a
 // file/dir has been saved successfully.
 func (b *TextProgress) CompleteItem(messageType, item string, previous, current *restic.Node, s archiver.ItemStats, d time.Duration) {
+	item = quote(item)
+
 	switch messageType {
 	case "dir new":
 		b.VV("new       %v, saved in %.3fs (%v added, %v stored, %v metadata)",
@@ -108,6 +112,15 @@ func (b *TextProgress) CompleteItem(messageType, item string, previous, current
 	}
 }
 
+func quote(filename string) string {
+	for _, r := range filename {
+		if r == ' ' || r == unicode.ReplacementChar || !unicode.IsPrint(r) {
+			return strconv.Quote(filename)
+		}
+	}
+	return filename
+}
+
 // ReportTotal sets the total stats up to now
 func (b *TextProgress) ReportTotal(item string, start time.Time, s archiver.ScanStats) {
 	b.V("scan finished in %.3fs: %v files, %s",

internal/ui/backup/text_test.go

@@ -0,0 +1,30 @@
+package backup
+
+import (
+	"strconv"
+	"testing"
+
+	rtest "github.com/restic/restic/internal/test"
+)
+
+func TestQuote(t *testing.T) {
+	for _, c := range []struct {
+		in        string
+		needQuote bool
+	}{
+		{"foo.bar/baz", false},
+		{"föó_bàŕ-bãẑ", false},
+		{" foo ", true},
+		{"foo bar", true},
+		{"foo\nbar", true},
+		{"foo\rbar", true},
+		{"foo\abar", true},
+		{"\xff", true},
+	} {
+		if c.needQuote {
+			rtest.Equals(t, strconv.Quote(c.in), quote(c.in))
+		} else {
+			rtest.Equals(t, c.in, quote(c.in))
+		}
+	}
+}