Fix prerender memory issue with circular references from meta tags

Co-authored-by: dummdidumm <[email protected]>

Author: Copilot

packages/kit/src/core/postbuild/crawl.js

@@ -230,29 +230,7 @@ export function crawl(html, base) {
 					const attr = name ?? property;
 
 					if (attr && CRAWLABLE_META_NAME_ATTRS.has(attr)) {
-						const resolved = resolve(base, content);
-						// Check for malformed URLs with consecutive slashes in the path
-						// Allow protocol-relative URLs (//example.com) and normal URLs (https://example.com)
-						// Block URLs with double slashes in paths (/path//file or domain//file)
-						let shouldInclude = true;
-						if (resolved.includes('//')) {
-							// If it starts with // it's protocol-relative, which is fine
-							if (resolved.startsWith('//')) {
-								shouldInclude = true;
-							}
-							// If it contains :// it's a full URL, which is fine
-							else if (resolved.includes('://')) {
-								shouldInclude = true;
-							}
-							// Otherwise it's a malformed path with double slashes
-							else {
-								shouldInclude = false;
-							}
-						}
-						
-						if (shouldInclude) {
-							hrefs.push(resolved);
-						}
+						hrefs.push(resolve(base, content));
 					}
 				}
 			}

packages/kit/src/core/postbuild/prerender.js

@@ -221,6 +221,26 @@ async function prerender({ hash, out, manifest_path, metadata, verbose, env }) {
 		const file = decoded.slice(config.paths.base.length + 1);
 		if (files.has(file)) return;
 
+		// Check for URLs that contain the prerender origin hostname in the path
+		// This can happen when meta tags reference URLs like "{page.url.host}/file.jpg"
+		// and can cause infinite loops during prerendering
+		if (config.prerender.origin !== 'http://sveltekit-prerender') {
+			// Extract hostname from prerender origin
+			const prerenderHost = new URL(config.prerender.origin).hostname;
+			// Check if the path starts with the prerender hostname (avoiding circular references)
+			if (decoded.startsWith(`/${prerenderHost}/`)) {
+				// This looks like a circular reference - handle as 404
+				handle_http_error({ status: 404, path: decoded, referrer, referenceType: 'linked' });
+				return;
+			}
+		} else {
+			// For the default sveltekit-prerender origin, check for the specific pattern
+			if (decoded.startsWith('/sveltekit-prerender/')) {
+				handle_http_error({ status: 404, path: decoded, referrer, referenceType: 'linked' });
+				return;
+			}
+		}
+
 		return q.add(() => visit(decoded, encoded || encodeURI(decoded), referrer, generated_from_id));
 	}
 
@@ -258,7 +278,13 @@ async function prerender({ hash, out, manifest_path, metadata, verbose, env }) {
 				}
 
 				// stuff in `static`
-				return readFileSync(join(config.files.assets, file));
+				const static_path = join(config.files.assets, file);
+				// Check if the static file exists before trying to read it
+				// This prevents potential issues with malformed paths or non-existent files
+				if (!existsSync(static_path)) {
+					throw new Error(`Static file not found: ${file}`);
+				}
+				return readFileSync(static_path);
 			},
 			emulator
 		});

packages/kit/test/build-errors/apps/prerender-meta-static-reference/src/routes/+layout.svelte

@@ -1,13 +1,17 @@
 <script>
+	import { page } from '$app/stores';
+	
 	let dynamic_title = 'My Page';
 	let dynamic_desc = 'Description';
+	// Simulate the original user's scenario where paths might have leading slashes
+	let a_path_to_svelte_kit_static_content = '/me.jpg'; // This would create double slashes
 </script>
 
 <svelte:head>
 	<meta property="og:title" content={dynamic_title} />
 	<meta property="og:description" content={dynamic_desc} />
-	<meta property="og:url" content="http://sveltekit-prerender" />
-	<meta property="og:image" content="sveltekit-prerender//me.jpg" />
+	<meta property="og:url" content={$page.url.origin} />
+	<meta property="og:image" content="{$page.url.host}/{a_path_to_svelte_kit_static_content}" />
 </svelte:head>
 
 <slot />

packages/kit/test/build-errors/prerender-meta-static-reference.spec.js

@@ -14,7 +14,10 @@ test('should handle HTTP errors in meta tags without infinite loop', { timeout }
 		encoding: 'utf8'
 	});
 
-	// The build should succeed and warn about favicon.png but not about malformed URLs
+	// The build should succeed and handle the circular reference properly
 	assert.match(result, /404.*favicon\.png/);
-	assert.ok(!result.includes('sveltekit-prerender//image'), 'Should not contain malformed URLs with double slashes');
+	// Should handle the circular reference from meta tag
+	assert.match(result, /404.*sveltekit-prerender.*me\.jpg/);
+	// Should complete successfully
+	assert.match(result, /✔ done/);
 });