Experimental implementation of the Web FileSystem api (#4116)

Author: jasnell

samples/webfs/README.md

@@ -0,0 +1,28 @@
+# Web File System API Example
+
+To run the example on http://localhost:8080
+
+```sh
+$ ./workerd serve config.capnp
+```
+
+To run using bazel
+
+```sh
+$ bazel run //src/workerd/server:workerd -- serve ~/cloudflare/workerd/samples/helloworld_esm/config.capnp
+```
+
+To create a standalone binary that can be run:
+
+```sh
+$ ./workerd compile config.capnp > helloworld
+
+$ ./helloworld
+```
+
+To test:
+
+```sh
+% curl http://localhost:8080
+Hello World
+```

samples/webfs/config.capnp

@@ -0,0 +1,35 @@
+# Imports the base schema for workerd configuration files.
+
+# Refer to the comments in /src/workerd/server/workerd.capnp for more details.
+
+using Workerd = import "/workerd/workerd.capnp";
+
+# A constant of type Workerd.Config defines the top-level configuration for an
+# instance of the workerd runtime. A single config file can contain multiple
+# Workerd.Config definitions and must have at least one.
+const helloWorldExample :Workerd.Config = (
+
+  # Every workerd instance consists of a set of named services. A worker, for instance,
+  # is a type of service. Other types of services can include external servers, the
+  # ability to talk to a network, or accessing a disk directory. Here we create a single
+  # worker service. The configuration details for the worker are defined below.
+  services = [ (name = "main", worker = .helloWorld) ],
+
+  # Each configuration defines the sockets on which the server will listen.
+  # Here, we create a single socket that will listen on localhost port 8080, and will
+  # dispatch to the "main" service that we defined above.
+  sockets = [ ( name = "http", address = "*:8080", http = (), service = "main" ) ]
+);
+
+# The definition of the actual helloWorld worker exposed using the "main" service.
+# In this example the worker is implemented as an ESM module (see worker.js).
+# The compatibilityDate is required. For more details on compatibility dates see:
+#   https://developers.cloudflare.com/workers/platform/compatibility-dates/
+
+const helloWorld :Workerd.Worker = (
+  modules = [
+    (name = "worker", esModule = embed "worker.js")
+  ],
+  compatibilityDate = "2025-05-01",
+  compatibilityFlags = ["enable_web_file_system", "experimental"]
+);

samples/webfs/worker.js

@@ -0,0 +1,23 @@
+// Copyright (c) 2017-2023 Cloudflare, Inc.
+// Licensed under the Apache 2.0 license found in the LICENSE file or at:
+//     https://opensource.org/licenses/Apache-2.0
+
+const dir = await navigator.storage.getDirectory();
+const bundle = await dir.getDirectoryHandle("tmp");
+const file = await bundle.getFileHandle("foo", { create: true });
+const handle = await file.createSyncAccessHandle();
+
+const enc = new TextEncoder();
+handle.write(enc.encode("Hello World"));
+handle.write(enc.encode("!!!\n"));
+console.log(handle.getSize());
+handle.close();
+
+const data = await file.getFile();
+console.log(await data.text());
+
+export default {
+  async fetch(req, env) {
+    return new Response("Hello World\n");
+  }
+};

src/workerd/api/BUILD.bazel

@@ -710,3 +710,9 @@ wd_test(
     args = ["--experimental"],
     data = ["tests/disable-importable-env-test.js"],
 )
+
+wd_test(
+    src = "tests/webfs-test.wd-test",
+    args = ["--experimental"],
+    data = ["tests/webfs-test.js"],
+)