add migration

models/migrations/migrations.go

@@ -212,6 +212,8 @@ var migrations = []Migration{
 	NewMigration("rename repo is_bare to repo is_empty", renameRepoIsBareToIsEmpty),
 	// v79 -> v80
 	NewMigration("add can close issues via commit in any branch", addCanCloseIssuesViaCommitInAnyBranch),
+	// v80 -> v81
+	NewMigration("delete orphaned attachments", deleteOrphanedAttachments),
 }
 
 // Migrate database to current version

models/migrations/v80.go

@@ -0,0 +1,47 @@
+// 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.
+
+package migrations
+
+import (
+	"os"
+
+	"code.gitea.io/gitea/models"
+	"code.gitea.io/gitea/modules/setting"
+	"github.com/go-xorm/xorm"
+)
+
+func deleteOrphanedAttachments(x *xorm.Engine) error {
+
+	type Attachment struct {
+		ID        int64  `xorm:"pk autoincr"`
+		UUID      string `xorm:"uuid UNIQUE"`
+		IssueID   int64  `xorm:"INDEX"`
+		ReleaseID int64  `xorm:"INDEX"`
+		CommentID int64
+	}
+
+	sess := x.NewSession()
+	defer sess.Close()
+
+	err := sess.BufferSize(setting.IterateBufferSize).
+		Where("comment_id = ? AND release_id = ?", 0, 0).Cols("uuid").
+		Iterate(new(Attachment),
+			func(idx int, bean interface{}) error {
+				attachment := bean.(*Attachment)
+
+				if err := os.RemoveAll(models.AttachmentLocalPath(attachment.UUID)); err != nil {
+					return err
+				}
+
+				_, err := sess.Delete(attachment)
+				return err
+			})
+
+	if err != nil {
+		return err
+	}
+
+	return sess.Commit()
+}