1 files changed, 36 insertions, 12 deletions
diff --git a/runtime/js/40_write_file.js b/runtime/js/40_write_file.js
index f8d8b3ab7..a32ef441b 100644
--- a/runtime/js/40_write_file.js
+++ b/runtime/js/40_write_file.js
@@ -5,6 +5,9 @@
   const ops = core.ops;
   const { abortSignal } = window.__bootstrap;
   const { pathFromURL } = window.__bootstrap.util;
+  const { open } = window.__bootstrap.files;
+  const { ReadableStreamPrototype } = window.__bootstrap.streams;
+  const { ObjectPrototypeIsPrototypeOf } = window.__bootstrap.primordials;
 
   function writeFileSync(
     path,
@@ -36,16 +39,29 @@
       options.signal[abortSignal.add](abortHandler);
     }
     try {
-      await core.opAsync(
-        "op_write_file_async",
-        pathFromURL(path),
-        options.mode,
-        options.append ?? false,
-        options.create ?? true,
-        options.createNew ?? false,
-        data,
-        cancelRid,
-      );
+      if (ObjectPrototypeIsPrototypeOf(ReadableStreamPrototype, data)) {
+        const file = await open(path, {
+          mode: options.mode,
+          append: options.append ?? false,
+          create: options.create ?? true,
+          createNew: options.createNew ?? false,
+          write: true,
+        });
+        await data.pipeTo(file.writable, {
+          signal: options.signal,
+        });
+      } else {
+        await core.opAsync(
+          "op_write_file_async",
+          pathFromURL(path),
+          options.mode,
+          options.append ?? false,
+          options.create ?? true,
+          options.createNew ?? false,
+          data,
+          cancelRid,
+        );
+      }
     } finally {
       if (options.signal) {
         options.signal[abortSignal.remove](abortHandler);
@@ -70,8 +86,16 @@
     data,
     options = {},
   ) {
-    const encoder = new TextEncoder();
-    return writeFile(path, encoder.encode(data), options);
+    if (ObjectPrototypeIsPrototypeOf(ReadableStreamPrototype, data)) {
+      return writeFile(
+        path,
+        data.pipeThrough(new TextEncoderStream()),
+        options,
+      );
+    } else {
+      const encoder = new TextEncoder();
+      return writeFile(path, encoder.encode(data), options);
+    }
   }
 
   window.__bootstrap.writeFile = {