🐛 fix gbk garbled

utils/file.go

@@ -1,9 +1,12 @@
 package utils
 
 import (
+	"bytes"
 	"encoding/json"
 	"github.com/Xhofe/alist/conf"
 	log "github.com/sirupsen/logrus"
+	"golang.org/x/text/encoding/simplifiedchinese"
+	"golang.org/x/text/transform"
 	"io/ioutil"
 	"os"
 	"path/filepath"
@@ -88,3 +91,38 @@ func ParsePath(path string) string {
 	}
 	return path
 }
+
+func IsGBK(data []byte) bool {
+	length := len(data)
+	var i int = 0
+	for i < length {
+		//fmt.Printf("for %x\n", data[i])
+		if data[i] <= 0xff {
+			//编码小于等于127,只有一个字节的编码，兼容ASCII吗
+			i++
+			continue
+		} else {
+			//大于127的使用双字节编码
+			if  data[i] >= 0x81 &&
+				data[i] <= 0xfe &&
+				data[i + 1] >= 0x40 &&
+				data[i + 1] <= 0xfe &&
+				data[i + 1] != 0xf7 {
+				i += 2
+				continue
+			} else {
+				return false
+			}
+		}
+	}
+	return true
+}
+
+func GbkToUtf8(s []byte) ([]byte, error) {
+	reader := transform.NewReader(bytes.NewReader(s), simplifiedchinese.GBK.NewDecoder())
+	d, e := ioutil.ReadAll(reader)
+	if e != nil {
+		return nil, e
+	}
+	return d, nil
+}