Allow more flexibility in choosing which requests get the COI workaro…

…und.

package.json

@@ -15,7 +15,6 @@
     "@codemirror/view": "^6.33.0",
     "@rollup/plugin-node-resolve": "^15.2.3",
     "@sqlite.org/sqlite-wasm": "^3.46.1-build1",
-    "mini-coi": "^0.4.2",
     "rollup": "^4.21.2",
     "rollup-plugin-license": "^3.5.2"
   },

tdoc/common/__init__.py

@@ -96,7 +96,7 @@ def on_builder_inited(app):
 
     # The file must be at the root of the website, to avoid limiting the scope
     # of the service worker to _static.
-    fileutil.copy_asset_file(_common / 'static.gen' / 'mini-coi.js',
+    fileutil.copy_asset_file(_common / 'static' / 'tdoc-coi.js',
                              app.builder.outdir, force=True)
 
 
@@ -106,15 +106,15 @@ def on_html_page_context(app, page, template, context, doctree):
     license_url = app.config.license_url
     if license_url: context['license_url'] = license_url
 
-    # Work around Cross-Origin Isoaltion issues when the corresponding headers
-    # cannot be set server-side.
-    app.add_js_file('../mini-coi.js', priority=0)
+    # Work around Cross-Origin Isolation issues when the relevant headers cannot
+    # be set server-side.
+    app.add_js_file('../tdoc-coi.js', priority=0,
+                    scope=context['pathto']('', resource=True))
 
+    # Add language-specific .js files.
     if doctree:
         for lang in sorted(Exec.find_nodes(doctree)):
             app.add_js_file(f'tdoc-{lang}.js', type='module')
-            # TODO: Add Cross-Origin-*-Policy headers in the dev server
-            # TODO: Work around inability to specify headers on GitHub Pages
 
 
 def add_reload_js(app, page, template, context, doctree):

tdoc/common/static/tdoc-coi.js

@@ -0,0 +1,54 @@
+// Copyright 2024 Remy Blank <[email protected]>
+// SPDX-License-Identifier: MIT
+
+(({document: doc, navigator: {serviceWorker: workers}}) => {
+    if (!doc) {
+        // Running in the service worker. Capture fetch() requests and add the
+        // relevant headers.
+        addEventListener('install', () => skipWaiting());
+        addEventListener('activate', e => e.waitUntil(clients.claim()));
+        addEventListener('fetch', e => {
+            const req = e.request;
+            if (req.cache === 'only-if-cached' && req.mode !== 'same-origin') {
+                return;
+            }
+            e.respondWith((async () => {
+                const resp = await fetch(req);
+                const {status, statusText, body} = resp;
+                if (!status || status >= 400) return resp;
+                const headers = new Headers(resp.headers);
+                headers.set('Cross-Origin-Embedder-Policy', 'require-corp');
+                headers.set('Cross-Origin-Opener-Policy', 'same-origin');
+                headers.set('Cross-Origin-Resource-Policy', 'cross-origin');
+                return new Response(resp.body, {status, statusText, headers});
+            })());
+        });
+        return;
+    }
+
+    // Running in the main thread. Register the service worker if necessary.
+    if (crossOriginIsolated) {
+        console.info("[t-doc] Already cross-origin isolated");
+        return;
+    }
+    if (!isSecureContext) {
+        console.warn("[t-doc] Not a secure context; COI workaround disabled");
+        return;
+    }
+    if (!workers) {
+        console.warn(
+            "[t-doc] No service worker container; COI workaround disabled");
+        return;
+    }
+    const script = doc.currentScript;
+    workers.register(script.src, {scope: script.getAttribute('scope')})
+        .then(reg => {
+            console.info('[t-doc] COI service worker registered');
+            reg.addEventListener('updatefound', () => location.reload());
+            if (reg.active && !workers.controller) location.reload();
+        })
+        .catch(e => {
+            console.error(
+                `[t-doc] Failed to register COI service worker: ${e}`);
+        });
+})(self);

tools/hatch_hooks.py

@@ -34,7 +34,6 @@ def initialize(self, version, build_data):
         self.app.display_info("Generating files")
         os.makedirs(static_gen, exist_ok=True)
         node_modules = root / 'node_modules'
-        shutil.copy2(node_modules / 'mini-coi' / 'mini-coi.js', static_gen)
         shutil.copytree(node_modules / '@sqlite.org' / 'sqlite-wasm'
                         / 'sqlite-wasm' / 'jswasm',
                         static_gen, symlinks=True, dirs_exist_ok=True)