Delete releases attachments if release is deleted (#6068)

* delete attachments from the database and file system

* add migration

* fix import statements

* fix package name

* remove conditional should in case the confi has been changed and the server restarted

* simplify deletion of attachments in DB

* fix CI build

* fix review

* add copyright in the proper place

* fix review

models/release.go

@@ -1,4 +1,5 @@
 // Copyright 2014 The Gogs Authors. All rights reserved.
+// Copyright 2019 The Gitea Authors. All rights reserved.
 // Use of this source code is governed by a MIT-style
 // license that can be found in the LICENSE file.
 
@@ -6,6 +7,7 @@ package models
 
 import (
 	"fmt"
+	"os"
 	"sort"
 	"strings"
 
@@ -357,6 +359,17 @@ func DeleteReleaseByID(id int64, doer *User, delTag bool) error {
 		return fmt.Errorf("LoadAttributes: %v", err)
 	}
 
+	if _, err := x.Delete(&Attachment{ReleaseID: id}); err != nil {
+		return err
+	}
+
+	for i := range rel.Attachments {
+		attachment := rel.Attachments[i]
+		if err := os.RemoveAll(attachment.LocalPath()); err != nil {
+			return err
+		}
+	}
+
 	mode, _ := AccessLevel(doer, rel.Repo)
 	if err := PrepareWebhooks(rel.Repo, HookEventRelease, &api.ReleasePayload{
 		Action:     api.HookReleaseDeleted,