3 files changed, 41 insertions, 34 deletions

diff --git a/js/dispatch.ts b/js/dispatch.ts
index 6edd2981c..babea5739 100644
--- a/js/dispatch.ts
+++ b/js/dispatch.ts
@@ -32,13 +32,9 @@ function flatbufferRecordFromBuf(buf: Uint8Array): FlatbufferRecord {
 }
 
 export function handleAsyncMsgFromRust(opId: number, ui8: Uint8Array): void {
+  const buf32 = new Int32Array(ui8.buffer, ui8.byteOffset, ui8.byteLength / 4);
   if (opId !== FLATBUFFER_OP_ID) {
     // Fast and new
-    const buf32 = new Int32Array(
-      ui8.buffer,
-      ui8.byteOffset,
-      ui8.byteLength / 4
-    );
     const recordMin = recordFromBufMinimal(opId, buf32);
     handleAsyncMsgFromRustMinimal(ui8, recordMin);
   } else {
diff --git a/js/dispatch_minimal.ts b/js/dispatch_minimal.ts
index 483342127..df0a290b2 100644
--- a/js/dispatch_minimal.ts
+++ b/js/dispatch_minimal.ts
@@ -52,19 +52,6 @@ export function handleAsyncMsgFromRustMinimal(
   promise!.resolve(result);
 }
 
-export function sendSyncMinimal(
-  opId: number,
-  arg: number,
-  zeroCopy: Uint8Array
-): number {
-  scratch32[0] = 0; // promiseId 0 indicates sync
-  scratch32[1] = arg;
-  const res = core.dispatch(opId, scratchBytes, zeroCopy)!;
-  const res32 = new Int32Array(res.buffer, res.byteOffset, 3);
-  const resRecord = recordFromBufMinimal(opId, res32);
-  return resRecord.result;
-}
-
 export function sendAsyncMinimal(
   opId: number,
   arg: number,
diff --git a/js/files.ts b/js/files.ts
index 1582d8fd4..eb899d738 100644
--- a/js/files.ts
+++ b/js/files.ts
@@ -11,12 +11,11 @@ import {
   SyncSeeker
 } from "./io";
 import * as dispatch from "./dispatch";
-import { sendAsyncMinimal, sendSyncMinimal } from "./dispatch_minimal";
+import { sendAsyncMinimal } from "./dispatch_minimal";
 import * as msg from "gen/cli/msg_generated";
 import { assert } from "./util";
 import * as flatbuffers from "./flatbuffers";
 
-// Warning: These constants defined in two places. Here and in cli/ops/mod.rs.
 const OP_READ = 1;
 const OP_WRITE = 2;
 
@@ -63,6 +62,26 @@ export async function open(
   return resOpen(await dispatch.sendAsync(...reqOpen(filename, mode)));
 }
 
+function reqRead(
+  rid: number,
+  p: Uint8Array
+): [flatbuffers.Builder, msg.Any, flatbuffers.Offset, Uint8Array] {
+  const builder = flatbuffers.createBuilder();
+  const inner = msg.Read.createRead(builder, rid);
+  return [builder, msg.Any.Read, inner, p];
+}
+
+function resRead(baseRes: null | msg.Base): number | EOF {
+  assert(baseRes != null);
+  assert(msg.Any.ReadRes === baseRes!.innerType());
+  const res = new msg.ReadRes();
+  assert(baseRes!.inner(res) != null);
+  if (res.eof()) {
+    return EOF;
+  }
+  return res.nread();
+}
+
 /** Read synchronously from a file ID into an array buffer.
  *
  * Return `number | EOF` for the operation.
@@ -74,14 +93,7 @@ export async function open(
  *
  */
 export function readSync(rid: number, p: Uint8Array): number | EOF {
-  const nread = sendSyncMinimal(OP_READ, rid, p);
-  if (nread < 0) {
-    throw new Error("read error");
-  } else if (nread == 0) {
-    return EOF;
-  } else {
-    return nread;
-  }
+  return resRead(dispatch.sendSync(...reqRead(rid, p)));
 }
 
 /** Read from a file ID into an array buffer.
@@ -106,6 +118,23 @@ export async function read(rid: number, p: Uint8Array): Promise<number | EOF> {
   }
 }
 
+function reqWrite(
+  rid: number,
+  p: Uint8Array
+): [flatbuffers.Builder, msg.Any, flatbuffers.Offset, Uint8Array] {
+  const builder = flatbuffers.createBuilder();
+  const inner = msg.Write.createWrite(builder, rid);
+  return [builder, msg.Any.Write, inner, p];
+}
+
+function resWrite(baseRes: null | msg.Base): number {
+  assert(baseRes != null);
+  assert(msg.Any.WriteRes === baseRes!.innerType());
+  const res = new msg.WriteRes();
+  assert(baseRes!.inner(res) != null);
+  return res.nbyte();
+}
+
 /** Write synchronously to the file ID the contents of the array buffer.
  *
  * Resolves with the number of bytes written.
@@ -116,12 +145,7 @@ export async function read(rid: number, p: Uint8Array): Promise<number | EOF> {
  *       Deno.writeSync(file.rid, data);
  */
 export function writeSync(rid: number, p: Uint8Array): number {
-  let result = sendSyncMinimal(OP_WRITE, rid, p);
-  if (result < 0) {
-    throw new Error("write error");
-  } else {
-    return result;
-  }
+  return resWrite(dispatch.sendSync(...reqWrite(rid, p)));
 }
 
 /** Write to the file ID the contents of the array buffer.