Update dag2file.go

[YZQ-zing]

package merkledag

import (
"encoding/json"
"strings"
)

// Hash to file

// example a path : /doc/tmp/temp.txt
func Hash2File(store KVStore, hash []byte, path string, hp HashPool) []byte {
// 根据hash和path， 返回对应的文件, hash对应的类型是tree
flag, _ := store.Has(hash)
if flag {
objBinary, _ := store.Get(hash)
var obj Object
json.Unmarshal(objBinary, &obj)
pathArr := strings.Split(path, "/")
cur := 1
return getFileByDir(obj, pathArr, cur, store)
}
return nil
}

func getFileByDir(obj Object, pathArr []string, cur int, store KVStore) []byte {
if cur >= len(pathArr) {
return nil
}
index := 0
for i := range obj.Links {
objType := string(obj.Data[index : index+4])
index += 4
objInfo := obj.Links[i]
if objInfo.Name != pathArr[cur] {
continue
}
switch objType {
case TREE:
objDirBinary, _ := store.Get(objInfo.Hash)
var objDir Object
json.Unmarshal(objDirBinary, &objDir)
ans := getFileByDir(objDir, pathArr, cur+1, store)
if ans != nil {
return ans
}
case BLOB:
ans, _ := store.Get(objInfo.Hash)
return ans
case LIST:
objLinkBinary, _ := store.Get(objInfo.Hash)
var objLink Object
json.Unmarshal(objLinkBinary, &objLink)
ans := getFileByList(objLink, store)
return ans
}
}
return nil
}

func getFileByList(obj Object, store KVStore) []byte {
ans := make([]byte, 0)
index := 0
for i := range obj.Links {
curObjType := string(obj.Data[index : index+4])
index += 4
curObjLink := obj.Links[i]
curObjBinary, _ := store.Get(curObjLink.Hash)
var curObj Object
json.Unmarshal(curObjBinary, &curObj)
if curObjType == BLOB {
ans = append(ans, curObjBinary...)
} else { //List
tmp := getFileByList(curObj, store)
ans = append(ans, tmp...)
}
}
return ans
}