fix(node/fs): node:fs.read and write should accept typed arrays other than Uint8Array (#25030)

Part of #25028.

Our underlying read/write operations in `io` assume the buffer is a
Uint8Array, but we were passing in other typed arrays (in the case above
it was `Int8Array`).

4 files changed, 31 insertions, 16 deletions

diff --git a/ext/node/polyfills/_fs/_fs_common.ts b/ext/node/polyfills/_fs/_fs_common.ts
index 069f9a3a1..ac0bf5a55 100644
--- a/ext/node/polyfills/_fs/_fs_common.ts
+++ b/ext/node/polyfills/_fs/_fs_common.ts
@@ -38,7 +38,7 @@ export type BinaryOptionsArgument =
 export type FileOptionsArgument = Encodings | FileOptions;
 
 export type ReadOptions = {
-  buffer: Buffer | Uint8Array;
+  buffer: Buffer | ArrayBufferView;
   offset: number;
   length: number;
   position: number | null;
diff --git a/ext/node/polyfills/_fs/_fs_read.ts b/ext/node/polyfills/_fs/_fs_read.ts
index e25f41e76..7b3d9fccd 100644
--- a/ext/node/polyfills/_fs/_fs_read.ts
+++ b/ext/node/polyfills/_fs/_fs_read.ts
@@ -9,6 +9,7 @@ import * as io from "ext:deno_io/12_io.js";
 import * as fs from "ext:deno_fs/30_fs.js";
 import { ReadOptions } from "ext:deno_node/_fs/_fs_common.ts";
 import {
+  arrayBufferViewToUint8Array,
   validateOffsetLengthRead,
   validatePosition,
 } from "ext:deno_node/internal/fs/utils.mjs";
@@ -16,6 +17,7 @@ import {
   validateBuffer,
   validateInteger,
 } from "ext:deno_node/internal/validators.mjs";
+import { isArrayBufferView } from "ext:deno_node/internal/util/types.ts";
 
 type readSyncOptions = {
   offset: number;
@@ -38,7 +40,7 @@ export function read(
 ): void;
 export function read(
   fd: number,
-  buffer: Buffer | Uint8Array,
+  buffer: ArrayBufferView,
   offset: number,
   length: number,
   position: number | null,
@@ -46,7 +48,7 @@ export function read(
 ): void;
 export function read(
   fd: number,
-  optOrBufferOrCb?: Buffer | Uint8Array | ReadOptions | Callback,
+  optOrBufferOrCb?: ArrayBufferView | ReadOptions | Callback,
   offsetOrCallback?: number | Callback,
   length?: number,
   position?: number | null,
@@ -75,9 +77,9 @@ export function read(
   }
 
   if (
-    optOrBufferOrCb instanceof Buffer || optOrBufferOrCb instanceof Uint8Array
+    isArrayBufferView(optOrBufferOrCb)
   ) {
-    buffer = optOrBufferOrCb;
+    buffer = arrayBufferViewToUint8Array(optOrBufferOrCb);
   } else if (typeof optOrBufferOrCb === "function") {
     offset = 0;
     buffer = Buffer.alloc(16384);
@@ -86,7 +88,7 @@ export function read(
   } else {
     const opt = optOrBufferOrCb as ReadOptions;
     if (
-      !(opt.buffer instanceof Buffer) && !(opt.buffer instanceof Uint8Array)
+      !isArrayBufferView(opt.buffer)
     ) {
       throw new ERR_INVALID_ARG_TYPE("buffer", [
         "Buffer",
@@ -94,8 +96,12 @@ export function read(
         "DataView",
       ], optOrBufferOrCb);
     }
+    if (opt.buffer === undefined) {
+      buffer = Buffer.alloc(16384);
+    } else {
+      buffer = arrayBufferViewToUint8Array(opt.buffer);
+    }
     offset = opt.offset ?? 0;
-    buffer = opt.buffer ?? Buffer.alloc(16384);
     length = opt.length ?? buffer.byteLength;
     position = opt.position ?? null;
   }
@@ -131,19 +137,19 @@ export function read(
 
 export function readSync(
   fd: number,
-  buffer: Buffer | Uint8Array,
+  buffer: ArrayBufferView,
   offset: number,
   length: number,
   position: number | null,
 ): number;
 export function readSync(
   fd: number,
-  buffer: Buffer | Uint8Array,
+  buffer: ArrayBufferView,
   opt: readSyncOptions,
 ): number;
 export function readSync(
   fd: number,
-  buffer: Buffer | Uint8Array,
+  buffer: ArrayBufferView,
   offsetOrOpt?: number | readSyncOptions,
   length?: number,
   position?: number | null,
@@ -156,6 +162,8 @@ export function readSync(
 
   validateBuffer(buffer);
 
+  buffer = arrayBufferViewToUint8Array(buffer);
+
   if (length == null) {
     length = 0;
   }
diff --git a/ext/node/polyfills/_fs/_fs_write.mjs b/ext/node/polyfills/_fs/_fs_write.mjs
index c0ae129d3..b4b133222 100644
--- a/ext/node/polyfills/_fs/_fs_write.mjs
+++ b/ext/node/polyfills/_fs/_fs_write.mjs
@@ -12,6 +12,7 @@ import {
 import * as io from "ext:deno_io/12_io.js";
 import * as fs from "ext:deno_fs/30_fs.js";
 import {
+  arrayBufferViewToUint8Array,
   getValidatedFd,
   validateOffsetLengthWrite,
   validateStringAfterArrayBufferView,
@@ -23,9 +24,7 @@ export function writeSync(fd, buffer, offset, length, position) {
   fd = getValidatedFd(fd);
 
   const innerWriteSync = (fd, buffer, offset, length, position) => {
-    if (buffer instanceof DataView) {
-      buffer = new Uint8Array(buffer.buffer);
-    }
+    buffer = arrayBufferViewToUint8Array(buffer);
     if (typeof position === "number") {
       fs.seekSync(fd, position, io.SeekMode.Start);
     }
@@ -69,9 +68,7 @@ export function write(fd, buffer, offset, length, position, callback) {
   fd = getValidatedFd(fd);
 
   const innerWrite = async (fd, buffer, offset, length, position) => {
-    if (buffer instanceof DataView) {
-      buffer = new Uint8Array(buffer.buffer);
-    }
+    buffer = arrayBufferViewToUint8Array(buffer);
     if (typeof position === "number") {
       await fs.seek(fd, position, io.SeekMode.Start);
     }
diff --git a/ext/node/polyfills/internal/fs/utils.mjs b/ext/node/polyfills/internal/fs/utils.mjs
index 9f3322bae..53184b9c3 100644
--- a/ext/node/polyfills/internal/fs/utils.mjs
+++ b/ext/node/polyfills/internal/fs/utils.mjs
@@ -986,6 +986,16 @@ export const validatePosition = hideStackFrames((position) => {
   }
 });
 
+/** @type {(buffer: ArrayBufferView) => Uint8Array} */
+export const arrayBufferViewToUint8Array = hideStackFrames(
+  (buffer) => {
+    if (!(buffer instanceof Uint8Array)) {
+      return new Uint8Array(buffer.buffer);
+    }
+    return buffer;
+  },
+);
+
 export const realpathCacheKey = Symbol("realpathCacheKey");
 export const constants = {
   kIoMaxLength,