ui/backup: Quote funny filenames

Fixes #2260, #4191.

internal/ui/termstatus/status.go

@@ -7,6 +7,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"strconv"
 	"strings"
 	"unicode"
 
@@ -325,6 +326,7 @@ func wideRune(r rune) bool {
 }
 
 // SetStatus updates the status lines.
+// The lines should not contain newlines; this method adds them.
 func (t *Terminal) SetStatus(lines []string) {
 	if len(lines) == 0 {
 		return
@@ -341,21 +343,31 @@ func (t *Terminal) SetStatus(lines []string) {
 		}
 	}
 
-	// make sure that all lines have a line break and are not too long
+	// Sanitize lines and truncate them if they're too long.
 	for i, line := range lines {
-		line = strings.TrimRight(line, "\n")
+		line = quote(line)
 		if width > 0 {
 			line = Truncate(line, width-2)
 		}
-		lines[i] = line + "\n"
+		if i < len(lines)-1 { // Last line gets no line break.
+			lines[i] = line + "\n"
+		}
 	}
 
-	// make sure the last line does not have a line break
-	last := len(lines) - 1
-	lines[last] = strings.TrimRight(lines[last], "\n")
-
 	select {
 	case t.status <- status{lines: lines}:
 	case <-t.closed:
 	}
 }
+
+// Quote lines with funny characters in them, meaning control chars, newlines,
+// tabs, anything else non-printable and invalid UTF-8.
+func quote(line string) string {
+	for _, r := range line {
+		// The replacement character usually means the input is not UTF-8.
+		if r == unicode.ReplacementChar || !unicode.IsPrint(r) {
+			return strconv.Quote(line)
+		}
+	}
+	return filename
+}

internal/ui/termstatus/status_test.go

@@ -1,6 +1,36 @@
 package termstatus
 
-import "testing"
+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 ", false},
+		{"foo bar", false},
+		{"foo\nbar", true},
+		{"foo\rbar", true},
+		{"foo\abar", true},
+		{"\xff", true},
+		{`c:\foo\bar`, false},
+		// Issue #2260: terminal control characters.
+		{"\x1bm_red_is_beautiful", true},
+	} {
+		if c.needQuote {
+			rtest.Equals(t, strconv.Quote(c.in), quote(c.in))
+		} else {
+			rtest.Equals(t, c.in, quote(c.in))
+		}
+	}
+}
 
 func TestTruncate(t *testing.T) {
 	var tests = []struct {