allow symlinked assets (#5089)

* allow symlinked assets

prettier

skip test on windows

Revert "skip test on windows"

This reverts commit f8e55e6.

skip test completely

* fix windows path

* fix

* i guess we need to recurse

* note to self

* fix some stuff

Co-authored-by: Rich Harris <hello@rich-harris.dev>

.changeset/violet-walls-jam.md

@@ -0,0 +1,5 @@
+---
+'@sveltejs/kit': patch
+---
+
+allow symlinked static assets in dev

packages/kit/src/core/dev/plugin.js

@@ -259,9 +259,7 @@ export const sveltekit = function (svelte_config) {
 							const file = svelte_config.kit.files.assets + pathname;
 
 							if (fs.existsSync(file) && !fs.statSync(file).isDirectory()) {
-								const has_correct_case = fs.realpathSync.native(file) === path.resolve(file);
-
-								if (has_correct_case) {
+								if (has_correct_case(file, svelte_config.kit.files.assets)) {
 									req.url = encodeURI(pathname); // don't need query/hash
 									asset_server(req, res);
 									return;
@@ -501,6 +499,27 @@ async function find_deps(vite, node, deps) {
 	await Promise.all(branches);
 }
 
+/**
+ * Determine if a file is being requested with the correct case,
+ * to ensure consistent behaviour between dev and prod and across
+ * operating systems. Note that we can't use realpath here,
+ * because we don't want to follow symlinks
+ * @param {string} file
+ * @param {string} assets
+ * @returns {boolean}
+ */
+function has_correct_case(file, assets) {
+	if (file === assets) return true;
+
+	const parent = path.dirname(file);
+
+	if (fs.readdirSync(parent).includes(path.basename(file))) {
+		return has_correct_case(parent, assets);
+	}
+
+	return false;
+}
+
 /**
  * @param {import('types').ValidatedConfig} svelte_config
  * @return {import('vite').Plugin[]}

packages/kit/test/apps/basics/static/symlink-from

@@ -0,0 +1 @@
+symlink-to

packages/kit/test/apps/basics/static/symlink-to/hello.txt

@@ -0,0 +1 @@
+hello

packages/kit/test/apps/basics/test/test.js

@@ -2583,6 +2583,12 @@ test.describe.parallel('Static files', () => {
 		const response = await request.get('/static.JSON');
 		expect(response.status()).toBe(404);
 	});
+
+	test('Serves symlinked asset', async ({ request }) => {
+		const response = await request.get('/symlink-from/hello.txt');
+		expect(response.status()).toBe(200);
+		expect(await response.text()).toBe('hello');
+	});
 });
 
 test.describe.parallel('Matchers', () => {