fix truncate utf8 string (#15828)

* fix truncate utf8 string.

* revoke truncated user info.

modules/base/tool.go

@@ -21,6 +21,7 @@ import (
 	"strings"
 	"time"
 	"unicode"
+	"unicode/utf8"
 
 	"code.gitea.io/gitea/modules/git"
 	"code.gitea.io/gitea/modules/log"
@@ -213,19 +214,19 @@ func EllipsisString(str string, length int) string {
 	if length <= 3 {
 		return "..."
 	}
-	if len(str) <= length {
+	if utf8.RuneCountInString(str) <= length {
 		return str
 	}
-	return str[:length-3] + "..."
+	return string([]rune(str)[:length-3]) + "..."
 }
 
 // TruncateString returns a truncated string with given limit,
 // it returns input string if length is not reached limit.
 func TruncateString(str string, limit int) string {
-	if len(str) < limit {
+	if utf8.RuneCountInString(str) < limit {
 		return str
 	}
-	return str[:limit]
+	return string([]rune(str)[:limit])
 }
 
 // StringsToInt64s converts a slice of string to a slice of int64.

modules/base/tool_test.go

@@ -170,6 +170,10 @@ func TestEllipsisString(t *testing.T) {
 	assert.Equal(t, "fo...", EllipsisString("foobar", 5))
 	assert.Equal(t, "foobar", EllipsisString("foobar", 6))
 	assert.Equal(t, "foobar", EllipsisString("foobar", 10))
+	assert.Equal(t, "测...", EllipsisString("测试文本一二三四", 4))
+	assert.Equal(t, "测试...", EllipsisString("测试文本一二三四", 5))
+	assert.Equal(t, "测试文...", EllipsisString("测试文本一二三四", 6))
+	assert.Equal(t, "测试文本一二三四", EllipsisString("测试文本一二三四", 10))
 }
 
 func TestTruncateString(t *testing.T) {
@@ -181,6 +185,10 @@ func TestTruncateString(t *testing.T) {
 	assert.Equal(t, "fooba", TruncateString("foobar", 5))
 	assert.Equal(t, "foobar", TruncateString("foobar", 6))
 	assert.Equal(t, "foobar", TruncateString("foobar", 7))
+	assert.Equal(t, "测试文本", TruncateString("测试文本一二三四", 4))
+	assert.Equal(t, "测试文本一", TruncateString("测试文本一二三四", 5))
+	assert.Equal(t, "测试文本一二", TruncateString("测试文本一二三四", 6))
+	assert.Equal(t, "测试文本一二三", TruncateString("测试文本一二三四", 7))
 }
 
 func TestStringsToInt64s(t *testing.T) {