1 files changed, 63 insertions, 2 deletions
diff --git a/ext/node/polyfills/worker_threads.ts b/ext/node/polyfills/worker_threads.ts
index 32f9885af..0529383cc 100644
--- a/ext/node/polyfills/worker_threads.ts
+++ b/ext/node/polyfills/worker_threads.ts
@@ -1,7 +1,7 @@
 // Copyright 2018-2023 the Deno authors. All rights reserved. MIT license.
 // Copyright Joyent and Node contributors. All rights reserved. MIT license.
 
-import { resolve, toFileUrl } from "ext:deno_node/path.ts";
+import { isAbsolute, resolve } from "ext:deno_node/path.ts";
 import { notImplemented } from "ext:deno_node/_utils.ts";
 import { EventEmitter, once } from "ext:deno_node/events.ts";
 import { BroadcastChannel } from "ext:deno_broadcast_channel/01_broadcast_channel.js";
@@ -32,6 +32,67 @@ export interface WorkerOptions {
   workerData?: unknown;
 }
 
+const WHITESPACE_ENCODINGS: Record<string, string> = {
+  "\u0009": "%09",
+  "\u000A": "%0A",
+  "\u000B": "%0B",
+  "\u000C": "%0C",
+  "\u000D": "%0D",
+  "\u0020": "%20",
+};
+
+function encodeWhitespace(string: string): string {
+  return string.replaceAll(/[\s]/g, (c) => {
+    return WHITESPACE_ENCODINGS[c] ?? c;
+  });
+}
+
+function toFileUrlPosix(path: string): URL {
+  if (!isAbsolute(path)) {
+    throw new TypeError("Must be an absolute path.");
+  }
+  const url = new URL("file:///");
+  url.pathname = encodeWhitespace(
+    path.replace(/%/g, "%25").replace(/\\/g, "%5C"),
+  );
+  return url;
+}
+
+function toFileUrlWin32(path: string): URL {
+  if (!isAbsolute(path)) {
+    throw new TypeError("Must be an absolute path.");
+  }
+  const [, hostname, pathname] = path.match(
+    /^(?:[/\\]{2}([^/\\]+)(?=[/\\](?:[^/\\]|$)))?(.*)/,
+  )!;
+  const url = new URL("file:///");
+  url.pathname = encodeWhitespace(pathname.replace(/%/g, "%25"));
+  if (hostname != null && hostname != "localhost") {
+    url.hostname = hostname;
+    if (!url.hostname) {
+      throw new TypeError("Invalid hostname.");
+    }
+  }
+  return url;
+}
+
+/**
+ * Converts a path string to a file URL.
+ *
+ * ```ts
+ *      toFileUrl("/home/foo"); // new URL("file:///home/foo")
+ *      toFileUrl("\\home\\foo"); // new URL("file:///home/foo")
+ *      toFileUrl("C:\\Users\\foo"); // new URL("file:///C:/Users/foo")
+ *      toFileUrl("\\\\127.0.0.1\\home\\foo"); // new URL("file://127.0.0.1/home/foo")
+ * ```
+ * @param path to convert to file URL
+ */
+function toFileUrl(path: string): URL {
+  return core.build.os == "windows"
+    ? toFileUrlWin32(path)
+    : toFileUrlPosix(path);
+}
+
 const kHandle = Symbol("kHandle");
 const PRIVATE_WORKER_THREAD_NAME = "$DENO_STD_NODE_WORKER_THREAD";
 class _Worker extends EventEmitter {
@@ -68,7 +129,7 @@ class _Worker extends EventEmitter {
         specifier =
           `data:text/javascript,(async function() {const { createRequire } = await import("node:module");const require = createRequire("${cwdFileUrl}");require("${specifier}");})();`;
       } else {
-        specifier = toFileUrl(specifier);
+        specifier = toFileUrl(specifier as string);
       }
     }
     const handle = this[kHandle] = new Worker(