fix: use scrollHeight for rendered iframe if offsetHeight is unavailable (#9508)

Fixes #9421.

Added integration test.

Co-authored-by: Gusted <postmaster@gusted.xyz>
Reviewed-on: https://codeberg.org/forgejo/forgejo/pulls/9508
Reviewed-by: Gusted <gusted@noreply.codeberg.org>
Reviewed-by: Michael Kriese <michael.kriese@gmx.de>
Co-authored-by: Bojidar Marinov <bojidar.marinov.bg@gmail.com>
Co-committed-by: Bojidar Marinov <bojidar.marinov.bg@gmail.com>

models/fixtures/repository.yml

@@ -1921,4 +1921,3 @@
   is_fsck_enabled: true
   close_issues_via_commit_in_any_branch: false
   topics: '[]'
-

modules/markup/renderer.go

@@ -326,7 +326,7 @@ func render(ctx *RenderContext, renderer Renderer, input io.Reader, output io.Wr
 	if r, ok := renderer.(ExternalRenderer); ok && r.DisplayInIFrame() {
 		// Append a short script to the iframe's contents, which will communicate the scroll height of the embedded document via postMessage, either once loaded (in case the containing page loads first) in response to a postMessage from external.js, in case the iframe loads first
 		// We use '*' as a target origin for postMessage, because can be certain we are embedded on the same domain, due to X-Frame-Options configured elsewhere. (Plus, the offsetHeight of an embedded document is likely not sensitive data anyway.)
-		_, _ = pw.Write([]byte("<script>{let postHeight = () => {window.parent.postMessage({frameHeight: document.documentElement.offsetHeight}, '*')}; window.addEventListener('load', postHeight); window.addEventListener('message', (event) => {if (event.source === window.parent && event.data.requestOffsetHeight) postHeight()});}</script>"))
+		_, _ = pw.Write([]byte("<script>{let postHeight = () => {window.parent.postMessage({frameHeight: document.documentElement.offsetHeight || document.documentElement.scrollHeight}, '*')}; window.addEventListener('load', postHeight); window.addEventListener('message', (event) => {if (event.source === window.parent && event.data.requestOffsetHeight) postHeight()});}</script>"))
 	}
 	_ = pw.Close()
 

services/repository/adopt_test.go

@@ -69,7 +69,7 @@ func TestCheckUnadoptedRepositories(t *testing.T) {
 func TestListUnadoptedRepositories_ListOptions(t *testing.T) {
 	require.NoError(t, unittest.PrepareTestDatabase())
 	username := "user2"
-	unadoptedList := []string{path.Join(username, "unadopted1"), path.Join(username, "unadopted2")}
+	unadoptedList := []string{path.Join(username, "rendering-test"), path.Join(username, "unadopted1"), path.Join(username, "unadopted2")}
 	for _, unadopted := range unadoptedList {
 		_ = os.Mkdir(path.Join(setting.RepoRootPath, unadopted+".git"), 0o755)
 	}
@@ -77,13 +77,13 @@ func TestListUnadoptedRepositories_ListOptions(t *testing.T) {
 	opts := db.ListOptions{Page: 1, PageSize: 1}
 	repoNames, count, err := ListUnadoptedRepositories(db.DefaultContext, "", &opts)
 	require.NoError(t, err)
-	assert.Equal(t, 2, count)
+	assert.Equal(t, 3, count)
 	assert.Equal(t, unadoptedList[0], repoNames[0])
 
 	opts = db.ListOptions{Page: 2, PageSize: 1}
 	repoNames, count, err = ListUnadoptedRepositories(db.DefaultContext, "", &opts)
 	require.NoError(t, err)
-	assert.Equal(t, 2, count)
+	assert.Equal(t, 3, count)
 	assert.Equal(t, unadoptedList[1], repoNames[0])
 }
 
@@ -97,7 +97,7 @@ func TestAdoptRepository(t *testing.T) {
 		path.Join(setting.RepoRootPath, username, unadopted+".git"),
 	))
 
-	opts := db.ListOptions{Page: 1, PageSize: 1}
+	opts := db.ListOptions{Page: 2, PageSize: 1}
 	repoNames, _, err := ListUnadoptedRepositories(db.DefaultContext, "", &opts)
 	require.NoError(t, err)
 	require.Contains(t, repoNames, path.Join(username, unadopted))

tests/e2e/fixtures/repo_unit.yml

@@ -0,0 +1,6 @@
+-
+  id: 1001
+  repo_id: 1002
+  type: 1
+  config: "{}"
+  created_unix: 946684810

tests/e2e/fixtures/repository.yml

@@ -11,3 +11,18 @@
   status: 0
   lfs_size: 8192
   topics: '[]'
+
+
+-
+  id: 1002
+  owner_id: 2
+  owner_name: user2
+  lower_name: rendering-test
+  name: rendering-test
+  default_branch: master
+  is_empty: false
+  is_archived: false
+  is_private: false
+  status: 0
+  num_issues: 0
+  topics: '[]'

tests/e2e/rendering-iframe.test.e2e.ts

@@ -0,0 +1,61 @@
+// Copyright 2025 The Forgejo Authors. All rights reserved.
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+// @watch start
+// web_src/js/markup/external.js
+// @watch end
+
+import {expect} from '@playwright/test';
+import {test} from './utils_e2e.ts';
+
+test('iframe renderer shrinks to shorter page', async ({page}, _workerInfo) => {
+  const previewPath = '/user2/rendering-test/src/branch/master/short.iframehtml';
+
+  const response = await page.goto(previewPath, {waitUntil: 'domcontentloaded'});
+  expect(response?.status()).toBe(200);
+
+  const preview = page.locator('iframe.external-render');
+  await expect.poll(async () => {
+    const boundingBox = await preview.boundingBox();
+    return boundingBox.height;
+  }).toBeLessThan(300);
+});
+
+test('iframe renderer expands to taller page', async ({page}, _workerInfo) => {
+  const previewPath = '/user2/rendering-test/src/branch/master/tall.iframehtml';
+
+  const response = await page.goto(previewPath, {waitUntil: 'domcontentloaded'});
+  expect(response?.status()).toBe(200);
+
+  const preview = page.locator('iframe.external-render');
+  await expect.poll(async () => {
+    const boundingBox = await preview.boundingBox();
+    return boundingBox.height;
+  }).toBeGreaterThan(300);
+});
+
+test('iframe renderer expands to taller page with absolutely-positioned body', async ({page}, _workerInfo) => {
+  const previewPath = '/user2/rendering-test/src/branch/master/absolute.iframehtml';
+
+  const response = await page.goto(previewPath, {waitUntil: 'domcontentloaded'});
+  expect(response?.status()).toBe(200);
+
+  const preview = page.locator('iframe.external-render');
+  await expect.poll(async () => {
+    const boundingBox = await preview.boundingBox();
+    return boundingBox.height;
+  }).toBeGreaterThan(300);
+});
+
+test('iframe renderer remains at default height if script breaks', async ({page}, _workerInfo) => {
+  const previewPath = '/user2/rendering-test/src/branch/master/fail.iframehtml';
+
+  const response = await page.goto(previewPath, {waitUntil: 'domcontentloaded'});
+  expect(response?.status()).toBe(200);
+
+  const preview = page.locator('iframe.external-render');
+  await expect.poll(async () => {
+    const boundingBox = await preview.boundingBox();
+    return boundingBox.height;
+  }).toBeCloseTo(300, 0.5);
+});

tests/gitea-repositories-meta/user2/rendering-test.git/HEAD

@@ -0,0 +1 @@
+ref: refs/heads/master

tests/gitea-repositories-meta/user2/rendering-test.git/config

@@ -0,0 +1,4 @@
+[core]
+	repositoryformatversion = 0
+	filemode = true
+	bare = true

tests/gitea-repositories-meta/user2/rendering-test.git/description

@@ -0,0 +1 @@
+Unnamed repository; edit this file 'description' to name the repository.

tests/gitea-repositories-meta/user2/rendering-test.git/info/exclude

@@ -0,0 +1,6 @@
+# git ls-files --others --exclude-from=.git/info/exclude
+# Lines that start with '#' are comments.
+# For a project mostly in C, the following would be a good set of
+# exclude patterns (uncomment them if you want to use them):
+# *.[oa]
+# *~

tests/gitea-repositories-meta/user2/rendering-test.git/objects/aa/ee434b5dbfce8a1fa9a0e21e7fa4743d7d5c9a

@@ -0,0 +1 @@
+x
+)JMU047g040031QHL*но)-IукL+JлMм(имa╦u╖┼-ЩR╨Эеmгv4ЗЩWqь╪ш╙<-13Y╘iЛ?∙и=ЖlK▌╡В/чo⌠z╟╕╙╢8#©╗Y╜Qж╣
*rO?тЬ-s╗тo╧ЕUF╗з▓дc╥_J~!\Бx╖Л{╓÷iо√:иsУ
сK

tests/gitea-repositories-meta/user2/rendering-test.git/refs/heads/master

@@ -0,0 +1 @@
+fafaad77cb54665ac800d1bf77e6a55bd355eabc

tests/mysql.ini.tmpl

@@ -125,3 +125,11 @@ ENABLED = false
 
 [cron.check_repo_stats]
 ENABLED = false
+
+# For iframe rendering tests
+[markup.iframehtml]
+ENABLED = true
+FILE_EXTENSIONS = .iframehtml
+RENDER_COMMAND = cat
+RENDER_CONTENT_MODE = iframe
+NEED_POSTPROCESS = false

tests/pgsql.ini.tmpl

@@ -139,3 +139,11 @@ ENABLED = false
 
 [cron.check_repo_stats]
 ENABLED = false
+
+# For iframe rendering tests
+[markup.iframehtml]
+ENABLED = true
+FILE_EXTENSIONS = .iframehtml
+RENDER_COMMAND = cat
+RENDER_CONTENT_MODE = iframe
+NEED_POSTPROCESS = false

tests/sqlite.ini.tmpl

@@ -126,3 +126,11 @@ ENABLED = false
 
 [cron.check_repo_stats]
 ENABLED = false
+
+# For iframe rendering tests
+[markup.iframehtml]
+ENABLED = true
+FILE_EXTENSIONS = .iframehtml
+RENDER_COMMAND = cat
+RENDER_CONTENT_MODE = iframe
+NEED_POSTPROCESS = false