NUAA-Open-Source/safeu-backend: item/downloadCount.go; 49 LoC

Found a possible issue in [NUAA-Open-Source/safeu-backend](https://www.github.com/NUAA-Open-Source/safeu-backend) at [item/downloadCount.go](https://github.com/NUAA-Open-Source/safeu-backend/blob/1df8ff0ce8e88fdbd60657cf6acacae02ae890a0/item/downloadCount.go#L106-L154)

Below is the message reported by the analyzer for this snippet of code. Beware that the analyzer only reports the first
issue it finds, so please do not limit your consideration to the contents of the below message.

>

[Click here to see the code in its original context.](https://github.com/NUAA-Open-Source/safeu-backend/blob/1df8ff0ce8e88fdbd60657cf6acacae02ae890a0/item/downloadCount.go#L106-L154)

Click here to show the 49 line(s) of Go which triggered the analyzer.

```go
for _, item := range itemList {
shouldDelete := false

// 检查有效期
if item.ExpiredAt.Before(time.Now()) {
// 文件过期
// 标记
shouldDelete = true
}

// 检查是否为当前文件，次数无限且时间有效直接返回
if item.DownCount == common.INFINITE_DOWNLOAD &&
item.Bucket == bucket &&
item.Path == path &&
!shouldDelete {

c.String(http.StatusOK, "OK")
return
}

// 更新当前文件下载次数--
if item.DownCount != common.INFINITE_DOWNLOAD &&
item.Bucket == bucket &&
item.Path == path &&
!shouldDelete {

item.DownCount -= 1
db.Model(&item).Update("down_count", item.DownCount)
log.Println(c.ClientIP(), " Item ", item.ID, " remain downloadable count: ", item.DownCount)
isMinus = true
}

if item.DownCount == common.INFINITE_DOWNLOAD && !shouldDelete {
continue
} else if item.DownCount < 0 || shouldDelete {
// 可下载次数小于 0 时才被动清除，否则存在剩余 1 次下载点击后直接触发删除的问题
// 删除文件组中该无效文件
err := DeleteItem(item.Bucket, item.Path)
if err != nil {
log.Println("Cannot delete item in bucket ", item.Bucket, ", path ", item.Path)
} else {
// 删除数据库记录
db.Delete(&item)
common.DeleteRedisRecodeFromRecode(item.ReCode)
log.Println(c.ClientIP(), " Deleted item id ", item.ID, " by retrieve code \"", retrieveCode, "\"")
isDelete = true
}
}
}

```

Click here to show extra information the analyzer produced.

```
No path was found through the callgraph that could lead to a function which writes a pointer argument.

No path was found through the callgraph that could lead to a function which passes a pointer to third-party code.

root signature {Model 1} was not found in the callgraph; reference was passed directly to third-party code
```

Leave a reaction on this issue to contribute to the project by classifying this instance as a **Bug** :-1:, **Mitigated** :+1:, or **Desirable Behavior** :rocket:
See the descriptions of the classifications [here](https://github.com/github-vet/rangeclosure-findings#how-can-i-help) for more information.

commit ID: 1df8ff0ce8e88fdbd60657cf6acacae02ae890a0