Use character display width for table padding

Using len(...) for table cell padding produced wrong results for unicode
chracters leading to misaligned tables. Implementation changed to take
the actual terminal display width into consideration.

internal/ui/format.go

@@ -8,6 +8,8 @@ import (
 	"math/bits"
 	"strconv"
 	"time"
+
+	"golang.org/x/text/width"
 )
 
 func FormatBytes(c uint64) string {
@@ -105,3 +107,24 @@ func ToJSONString(status interface{}) string {
 	}
 	return buf.String()
 }
+
+// TerminalDisplayWidth returns the number of terminal cells needed to display s
+func TerminalDisplayWidth(s string) int {
+	width := 0
+	for _, r := range s {
+		width += terminalDisplayRuneWidth(r)
+	}
+
+	return width
+}
+
+func terminalDisplayRuneWidth(r rune) int {
+	switch width.LookupRune(r).Kind() {
+	case width.EastAsianWide, width.EastAsianFullwidth:
+		return 2
+	case width.EastAsianNarrow, width.EastAsianHalfwidth, width.EastAsianAmbiguous, width.Neutral:
+		return 1
+	default:
+		return 0
+	}
+}

internal/ui/format_test.go

@@ -84,3 +84,21 @@ func TestParseBytesInvalid(t *testing.T) {
 		test.Equals(t, int64(0), v)
 	}
 }
+
+func TestTerminalDisplayWidth(t *testing.T) {
+	for _, c := range []struct {
+		input string
+		want  int
+	}{
+		{"foo", 3},
+		{"aéb", 3},
+		{"ab", 3},
+		{"a’b", 3},
+		{"aあb", 4},
+	} {
+		if got := TerminalDisplayWidth(c.input); got != c.want {
+			t.Errorf("wrong display width for '%s', want %d, got %d", c.input, c.want, got)
+		}
+	}
+
+}

internal/ui/table/table.go

@@ -6,6 +6,8 @@ import (
 	"strings"
 
 	"text/template"
+
+	"github.com/restic/restic/internal/ui"
 )
 
 // Table contains data for a table to be printed.
@@ -89,7 +91,7 @@ func printLine(w io.Writer, print func(io.Writer, string) error, sep string, dat
 			}
 
 			// apply padding
-			pad := widths[fieldNum] - len(v)
+			pad := widths[fieldNum] - ui.TerminalDisplayWidth(v)
 			if pad > 0 {
 				v += strings.Repeat(" ", pad)
 			}
@@ -139,16 +141,16 @@ func (t *Table) Write(w io.Writer) error {
 	columnWidths := make([]int, columns)
 	for i, desc := range t.columns {
 		for _, line := range strings.Split(desc, "\n") {
-			if columnWidths[i] < len(line) {
-				columnWidths[i] = len(desc)
+			if columnWidths[i] < ui.TerminalDisplayWidth(line) {
+				columnWidths[i] = ui.TerminalDisplayWidth(desc)
 			}
 		}
 	}
 	for _, line := range lines {
 		for i, content := range line {
 			for _, l := range strings.Split(content, "\n") {
-				if columnWidths[i] < len(l) {
-					columnWidths[i] = len(l)
+				if columnWidths[i] < ui.TerminalDisplayWidth(l) {
+					columnWidths[i] = ui.TerminalDisplayWidth(l)
 				}
 			}
 		}
@@ -159,7 +161,7 @@ func (t *Table) Write(w io.Writer) error {
 	for _, width := range columnWidths {
 		totalWidth += width
 	}
-	totalWidth += (columns - 1) * len(t.CellSeparator)
+	totalWidth += (columns - 1) * ui.TerminalDisplayWidth(t.CellSeparator)
 
 	// write header
 	if len(t.columns) > 0 {

internal/ui/table/table_test.go

@@ -126,7 +126,7 @@ foo        2018-08-19 22:22:22  xxx  other  /home/user/other
 					Time       string
 					Tags, Dirs []string
 				}
-				table.AddRow(data{"foo", "2018-08-19 22:22:22", []string{"work", "go"}, []string{"/home/user/work", "/home/user/go"}})
+				table.AddRow(data{"foo", "2018-08-19 22:22:22", []string{"work", "go’s"}, []string{"/home/user/work", "/home/user/go"}})
 				table.AddRow(data{"foo", "2018-08-19 22:22:22", []string{"other"}, []string{"/home/user/other"}})
 				table.AddRow(data{"foo", "2018-08-19 22:22:22", []string{"other", "bar"}, []string{"/home/user/other"}})
 				return table
@@ -135,7 +135,7 @@ foo        2018-08-19 22:22:22  xxx  other  /home/user/other
 host name  time                 zz   tags   dirs
 ------------------------------------------------------------
 foo        2018-08-19 22:22:22  xxx  work   /home/user/work
-                                     go     /home/user/go
+                                     go’s   /home/user/go
 foo        2018-08-19 22:22:22  xxx  other  /home/user/other
 foo        2018-08-19 22:22:22  xxx  other  /home/user/other
                                      bar