fix: 404 empty paginated sitemap pages (#3797)

Author: idoshamun

__tests__/sitemaps.ts

@@ -258,6 +258,10 @@ describe('GET /sitemaps/posts-:page.xml', () => {
       '<loc>http://localhost:5002/posts/p6-p6</loc>',
     );
   });
+
+  it('should return 404 for paginated pages with no rows', async () => {
+    await request(app.server).get('/sitemaps/posts-3.xml').expect(404);
+  });
 });
 
 describe('GET /sitemaps/posts.xml (type filtering)', () => {
@@ -1211,6 +1215,10 @@ describe('GET /sitemaps/evergreen.xml', () => {
     expect(res.text).toContain('/posts/evergreen-no-author-evergreen-norep');
     expect(res.text).not.toContain('/posts/evergreen-low-rep-evergreen-lowrep');
   });
+
+  it('should return 404 for paginated pages with no rows', async () => {
+    await request(app.server).get('/sitemaps/evergreen-2.xml').expect(404);
+  });
 });
 
 describe('GET /sitemaps/archive-index.xml', () => {

src/routes/sitemaps.ts

@@ -230,7 +230,7 @@ const buildSitemapXmlStream = async <T extends ObjectLiteral>(
 };
 
 const getSitemapPageCount = (totalPosts: number): number =>
-  Math.max(1, Math.ceil(totalPosts / getPaginatedSitemapLimit()));
+  Math.ceil(totalPosts / getPaginatedSitemapLimit());
 
 const getReplicaQueryCount = async (
   con: DataSource,
@@ -245,6 +245,20 @@ const getReplicaQueryCount = async (
   }
 };
 
+const hasPaginatedSitemapPage = async (
+  con: DataSource,
+  buildQuery: (source: EntityManager, page: number) => SelectQueryBuilder<Post>,
+  page: number,
+): Promise<boolean> => {
+  const queryRunner = con.createQueryRunner('slave');
+
+  try {
+    return !!(await buildQuery(queryRunner.manager, page).limit(1).getRawOne());
+  } finally {
+    await queryRunner.release();
+  }
+};
+
 const buildSitemapIndexEntries = (
   prefix: string,
   sitemapCount: number,
@@ -823,6 +837,10 @@ export default async function (fastify: FastifyInstance): Promise<void> {
 
     const con = await createOrGetConnection();
 
+    if (!(await hasPaginatedSitemapPage(con, buildPostsSitemapQuery, page))) {
+      return res.code(404).send();
+    }
+
     return res
       .type('application/xml')
       .header('cache-control', SITEMAP_CACHE_CONTROL)
@@ -849,6 +867,12 @@ export default async function (fastify: FastifyInstance): Promise<void> {
 
     const con = await createOrGetConnection();
 
+    if (
+      !(await hasPaginatedSitemapPage(con, buildEvergreenSitemapQuery, page))
+    ) {
+      return res.code(404).send();
+    }
+
     return res
       .type('application/xml')
       .header('cache-control', SITEMAP_CACHE_CONTROL)