From c14ec0dcb5ecfd125c49bcbbbdff2dfddc9e2183 Mon Sep 17 00:00:00 2001
From: Jan-Lukas Else <mail@jlelse.de>
Date: Fri, 23 Jul 2021 09:53:35 +0200
Subject: [PATCH] Save paths of deleted posts and show 410 error

---
 databaseMigrations.go | 10 ++++++++++
 errors.go             |  4 ++++
 http.go               |  8 ++++++++
 postsDb.go            | 11 ++++++++++-
 4 files changed, 32 insertions(+), 1 deletion(-)

diff --git a/databaseMigrations.go b/databaseMigrations.go
index 56d2ecb..f7fdf79 100644
--- a/databaseMigrations.go
+++ b/databaseMigrations.go
@@ -240,6 +240,16 @@ func migrateDb(db *sql.DB, logging bool) error {
 					return err
 				},
 			},
+			&migrator.Migration{
+				Name: "00020",
+				Func: func(tx *sql.Tx) error {
+					_, err := tx.Exec(`
+					create table deleted (path text primary key);
+					create index index_post_parameters_par_val_pat on post_parameters (parameter, value, path);
+					`)
+					return err
+				},
+			},
 		),
 	)
 	if err != nil {
diff --git a/errors.go b/errors.go
index 0769270..6eb2d9f 100644
--- a/errors.go
+++ b/errors.go
@@ -17,6 +17,10 @@ func (a *goBlog) serve404(w http.ResponseWriter, r *http.Request) {
 	a.serveError(w, r, fmt.Sprintf("%s was not found", r.RequestURI), http.StatusNotFound)
 }
 
+func (a *goBlog) serve410(w http.ResponseWriter, r *http.Request) {
+	a.serveError(w, r, fmt.Sprintf("%s doesn't exist anymore", r.RequestURI), http.StatusGone)
+}
+
 func (a *goBlog) serveNotAllowed(w http.ResponseWriter, r *http.Request) {
 	a.serveError(w, r, "", http.StatusMethodNotAllowed)
 }
diff --git a/http.go b/http.go
index 409fc98..44623c2 100644
--- a/http.go
+++ b/http.go
@@ -493,6 +493,8 @@ func (a *goBlog) servePostsAliasesRedirects(pmh ...func(http.Handler) http.Handl
 		select 'post', status from posts where path = @path
 		union all
 		select 'alias', path from post_parameters where parameter = 'aliases' and value = @path
+		union all
+		select 'deleted', '' from deleted where path = @path
 		limit 1
 		`, sql.Named("path", path))
 		if err != nil {
@@ -527,6 +529,12 @@ func (a *goBlog) servePostsAliasesRedirects(pmh ...func(http.Handler) http.Handl
 					http.Redirect(w, r, value, http.StatusFound)
 				}).ServeHTTP(w, r)
 				return
+			case "deleted":
+				// Is deleted, serve 410
+				alicePrivate.Append(a.cache.cacheMiddleware).ThenFunc(func(w http.ResponseWriter, r *http.Request) {
+					a.serve410(w, r)
+				}).ServeHTTP(w, r)
+				return
 			}
 		}
 		// No post, check regex redirects or serve 404 error
diff --git a/postsDb.go b/postsDb.go
index f822170..106e527 100644
--- a/postsDb.go
+++ b/postsDb.go
@@ -204,11 +204,20 @@ func (db *database) deletePost(path string) (*post, error) {
 	if path == "" {
 		return nil, nil
 	}
+	db.pcm.Lock()
+	defer db.pcm.Unlock()
 	p, err := db.getPost(path)
 	if err != nil {
 		return nil, err
 	}
-	_, err = db.exec("begin;delete from posts where path = ?;delete from post_parameters where path = ?;commit;", dbNoCache, p.Path, p.Path)
+	_, err = db.exec(
+		`begin;
+		delete from posts where path = ?;
+		delete from post_parameters where path = ?;
+		insert or ignore into deleted (path) values (?);
+		commit;`,
+		dbNoCache, p.Path, p.Path, p.Path,
+	)
 	if err != nil {
 		return nil, err
 	}