buffer: treat detached ArrayBuffers as empty

Treat detached ArrayBuffers and Buffer or TypedArray views backed by
them as zero-length inputs in buffer.isUtf8() and buffer.isAscii(). Both
functions now return true for these inputs, consistent with other empty
inputs.

Signed-off-by: Archkon <180910180+Archkon@users.noreply.github.com>
PR-URL: #64504
Fixes: #64503
Reviewed-By: James M Snell <jasnell@gmail.com>

Author: Archkon

doc/api/buffer.md

@@ -5303,6 +5303,11 @@ npx codemod@latest @nodejs/buffer-atob-btoa
 added:
   - v19.6.0
   - v18.15.0
+changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/64504
+    description: Detached `ArrayBuffer`s and views backed by them are treated
+                 as empty.
 -->
 
 * `input` {Buffer | ArrayBuffer | TypedArray} The input to validate.
@@ -5311,14 +5316,19 @@ added:
 This function returns `true` if `input` contains only valid ASCII-encoded data,
 including the case in which `input` is empty.
 
-Throws if the `input` is a detached array buffer.
+A detached `ArrayBuffer`, or a `TypedArray` backed by one, is treated as empty.
 
 ### `buffer.isUtf8(input)`
 
 <!-- YAML
 added:
   - v19.4.0
   - v18.14.0
+changes:
+  - version: REPLACEME
+    pr-url: https://github.com/nodejs/node/pull/64504
+    description: Detached `ArrayBuffer`s and views backed by them are treated
+                 as empty.
 -->
 
 * `input` {Buffer | ArrayBuffer | TypedArray} The input to validate.
@@ -5327,7 +5337,7 @@ added:
 This function returns `true` if `input` contains only valid UTF-8-encoded data,
 including the case in which `input` is empty.
 
-Throws if the `input` is a detached array buffer.
+A detached `ArrayBuffer`, or a `TypedArray` backed by one, is treated as empty.
 
 ### `buffer.INSPECT_MAX_BYTES`
 

src/node_buffer.cc

@@ -1302,31 +1302,17 @@ void FastSwap64(Local<Value> receiver,
 
 static CFunction fast_swap64(CFunction::Make(FastSwap64));
 
-struct ValidationResult {
-  bool is_valid;
-  bool was_detached;
-};
-
-static ValidationResult ValidateUtf8(Local<Value> value) {
+static bool ValidateUtf8(Local<Value> value) {
   ArrayBufferViewContents<char> abv(value);
-  bool was_detached = abv.WasDetached();
-  return {!was_detached && simdutf::validate_utf8(abv.data(), abv.length()),
-          was_detached};
+  return abv.length() == 0 || simdutf::validate_utf8(abv.data(), abv.length());
 }
 
 static void IsUtf8(const FunctionCallbackInfo<Value>& args) {
-  Environment* env = Environment::GetCurrent(args);
   CHECK_EQ(args.Length(), 1);
   CHECK(args[0]->IsTypedArray() || args[0]->IsArrayBuffer() ||
         args[0]->IsSharedArrayBuffer());
 
-  const ValidationResult result = ValidateUtf8(args[0]);
-  if (result.was_detached) {
-    return node::THROW_ERR_INVALID_STATE(
-        env, "Cannot validate on a detached buffer");
-  }
-
-  args.GetReturnValue().Set(result.is_valid);
+  args.GetReturnValue().Set(ValidateUtf8(args[0]));
 }
 
 static bool FastIsUtf8(Local<Value> receiver,
@@ -1335,40 +1321,23 @@ static bool FastIsUtf8(Local<Value> receiver,
                        FastApiCallbackOptions& options) {
   TRACK_V8_FAST_API_CALL("buffer.isUtf8");
   HandleScope scope(options.isolate);
-
-  const ValidationResult result = ValidateUtf8(value);
-  if (result.was_detached) {
-    node::THROW_ERR_INVALID_STATE(options.isolate,
-                                  "Cannot validate on a detached buffer");
-    return false;
-  }
-  return result.is_valid;
+  return ValidateUtf8(value);
 }
 
 static CFunction fast_is_utf8(CFunction::Make(FastIsUtf8));
 
-static ValidationResult ValidateAscii(Local<Value> value) {
+static bool ValidateAscii(Local<Value> value) {
   ArrayBufferViewContents<char> abv(value);
-  bool was_detached = abv.WasDetached();
-  return {
-      !was_detached &&
-          !simdutf::validate_ascii_with_errors(abv.data(), abv.length()).error,
-      was_detached};
+  return abv.length() == 0 ||
+         !simdutf::validate_ascii_with_errors(abv.data(), abv.length()).error;
 }
 
 static void IsAscii(const FunctionCallbackInfo<Value>& args) {
-  Environment* env = Environment::GetCurrent(args);
   CHECK_EQ(args.Length(), 1);
   CHECK(args[0]->IsTypedArray() || args[0]->IsArrayBuffer() ||
         args[0]->IsSharedArrayBuffer());
 
-  const ValidationResult result = ValidateAscii(args[0]);
-  if (result.was_detached) {
-    return node::THROW_ERR_INVALID_STATE(
-        env, "Cannot validate on a detached buffer");
-  }
-
-  args.GetReturnValue().Set(result.is_valid);
+  args.GetReturnValue().Set(ValidateAscii(args[0]));
 }
 
 static bool FastIsAscii(Local<Value> receiver,
@@ -1377,14 +1346,7 @@ static bool FastIsAscii(Local<Value> receiver,
                         FastApiCallbackOptions& options) {
   TRACK_V8_FAST_API_CALL("buffer.isAscii");
   HandleScope scope(options.isolate);
-
-  const ValidationResult result = ValidateAscii(value);
-  if (result.was_detached) {
-    node::THROW_ERR_INVALID_STATE(options.isolate,
-                                  "Cannot validate on a detached buffer");
-    return false;
-  }
-  return result.is_valid;
+  return ValidateAscii(value);
 }
 
 static CFunction fast_is_ascii(CFunction::Make(FastIsAscii));

test/parallel/test-buffer-isascii.js

@@ -30,13 +30,20 @@ assert.strictEqual(isAscii(Buffer.from([])), true);
 });
 
 {
-  // Test with detached array buffers
-  const arrayBuffer = new ArrayBuffer(1024);
+  // Detached array buffers and views are treated as empty.
+  const arrayBuffer = new ArrayBuffer(1);
+  const typedArray = new Uint8Array(arrayBuffer);
+  typedArray[0] = 0xff;
+  const inputs = [
+    arrayBuffer,
+    typedArray,
+    Buffer.from(arrayBuffer),
+  ];
+  for (const input of inputs) {
+    assert.strictEqual(isAscii(input), false);
+  }
   structuredClone(arrayBuffer, { transfer: [arrayBuffer] });
-  assert.throws(
-    () => { isAscii(arrayBuffer); },
-    {
-      code: 'ERR_INVALID_STATE'
-    }
-  );
+  for (const input of inputs) {
+    assert.strictEqual(isAscii(input), true);
+  }
 }

test/parallel/test-buffer-isutf8.js

@@ -74,13 +74,20 @@ assert.strictEqual(isUtf8(Buffer.from([])), true);
 });
 
 {
-  // Test with detached array buffers
-  const arrayBuffer = new ArrayBuffer(1024);
+  // Detached array buffers and views are treated as empty.
+  const arrayBuffer = new ArrayBuffer(1);
+  const typedArray = new Uint8Array(arrayBuffer);
+  typedArray[0] = 0xff;
+  const inputs = [
+    arrayBuffer,
+    typedArray,
+    Buffer.from(arrayBuffer),
+  ];
+  for (const input of inputs) {
+    assert.strictEqual(isUtf8(input), false);
+  }
   structuredClone(arrayBuffer, { transfer: [arrayBuffer] });
-  assert.throws(
-    () => { isUtf8(arrayBuffer); },
-    {
-      code: 'ERR_INVALID_STATE'
-    }
-  );
+  for (const input of inputs) {
+    assert.strictEqual(isUtf8(input), true);
+  }
 }