fix(node/fs): Use correct offset and length in node:fs.read and write (#25049)

My fix in #25030 was buggy, I forgot to pass the `byteOffset` and
`byteLength`. Whoops.

I also discovered that fs.read was not respecting the `offset` argument,
and we were constructing a new `Buffer` for the callback instead of just
passing the original one (which is what node does, and the @types/node
definitions also indicate the callback should get the same type).
Fixes #25028.

1 files changed, 11 insertions, 4 deletions

diff --git a/tests/unit_node/_fs/_fs_handle_test.ts b/tests/unit_node/_fs/_fs_handle_test.ts
index ea6af9c29..755e091fd 100644
--- a/tests/unit_node/_fs/_fs_handle_test.ts
+++ b/tests/unit_node/_fs/_fs_handle_test.ts
@@ -38,11 +38,15 @@ Deno.test("read specify opt", async function () {
     buffer: new Buffer(byteLength),
     offset: 6,
     length: 5,
+    position: 6,
   };
   let res = await fileHandle.read(opt);
 
-  assertEquals(res.bytesRead, byteLength);
-  assertEquals(new TextDecoder().decode(res.buffer as Uint8Array), "world");
+  assertEquals(res.bytesRead, 5);
+  assertEquals(
+    new TextDecoder().decode(res.buffer.subarray(6) as Uint8Array),
+    "world",
+  );
 
   const opt2 = {
     buffer: new Buffer(byteLength),
@@ -51,8 +55,11 @@ Deno.test("read specify opt", async function () {
   };
   res = await fileHandle.read(opt2);
 
-  assertEquals(res.bytesRead, byteLength);
-  assertEquals(decoder.decode(res.buffer as Uint8Array), "hello");
+  assertEquals(res.bytesRead, 5);
+  assertEquals(
+    decoder.decode(res.buffer.subarray(0, 5) as Uint8Array),
+    "hello",
+  );
 
   await fileHandle.close();
 });