util: make inspect more reliable

lib/util.js

@@ -290,7 +290,7 @@ function formatValue(ctx, value, recurseTimes) {
     }
     // Fast path for ArrayBuffer.  Can't do the same for DataView because it
     // has a non-primitive .buffer property that we need to recurse for.
-    if (value instanceof ArrayBuffer) {
+    if (binding.isArrayBuffer(value)) {
       return `${getConstructorOf(value).name}` +
              ` { byteLength: ${formatNumber(ctx, value.byteLength)} }`;
     }
@@ -328,18 +328,18 @@ function formatValue(ctx, value, recurseTimes) {
       keys.unshift('size');
     empty = value.size === 0;
     formatter = formatMap;
-  } else if (value instanceof ArrayBuffer) {
+  } else if (binding.isArrayBuffer(value)) {
     braces = ['{', '}'];
     keys.unshift('byteLength');
     visibleKeys.byteLength = true;
-  } else if (value instanceof DataView) {
+  } else if (binding.isDataView(value)) {
     braces = ['{', '}'];
     // .buffer goes last, it's not a primitive like the others.
     keys.unshift('byteLength', 'byteOffset', 'buffer');
     visibleKeys.byteLength = true;
     visibleKeys.byteOffset = true;
     visibleKeys.buffer = true;
-  } else if (isTypedArray(value)) {
+  } else if (binding.isTypedArray(value)) {
     braces = ['[', ']'];
     formatter = formatTypedArray;
     if (ctx.showHidden) {
@@ -679,19 +679,6 @@ function reduceToSingleString(output, base, braces) {
 }
 
 
-function isTypedArray(value) {
-  return value instanceof Float32Array ||
-         value instanceof Float64Array ||
-         value instanceof Int16Array ||
-         value instanceof Int32Array ||
-         value instanceof Int8Array ||
-         value instanceof Uint16Array ||
-         value instanceof Uint32Array ||
-         value instanceof Uint8Array ||
-         value instanceof Uint8ClampedArray;
-}
-
-
 // NOTE: These type checking functions intentionally don't use `instanceof`
 // because it is fragile and can be easily faked with `Object.create()`.
 exports.isArray = Array.isArray;

src/node_util.cc

@@ -30,6 +30,24 @@ static void IsPromise(const FunctionCallbackInfo<Value>& args) {
 }
 
 
+static void IsTypedArray(const FunctionCallbackInfo<Value>& args) {
+  CHECK_EQ(1, args.Length());
+  args.GetReturnValue().Set(args[0]->IsTypedArray());
+}
+
+
+static void IsArrayBuffer(const FunctionCallbackInfo<Value>& args) {
+  CHECK_EQ(1, args.Length());
+  args.GetReturnValue().Set(args[0]->IsArrayBuffer());
+}
+
+
+static void IsDataView(const FunctionCallbackInfo<Value>& args) {
+  CHECK_EQ(1, args.Length());
+  args.GetReturnValue().Set(args[0]->IsDataView());
+}
+
+
 static void GetHiddenValue(const FunctionCallbackInfo<Value>& args) {
   Environment* env = Environment::GetCurrent(args);
 
@@ -53,6 +71,9 @@ void Initialize(Local<Object> target,
   env->SetMethod(target, "isMapIterator", IsMapIterator);
   env->SetMethod(target, "isSetIterator", IsSetIterator);
   env->SetMethod(target, "isPromise", IsPromise);
+  env->SetMethod(target, "isTypedArray", IsTypedArray);
+  env->SetMethod(target, "isArrayBuffer", IsArrayBuffer);
+  env->SetMethod(target, "isDataView", IsDataView);
   env->SetMethod(target, "getHiddenValue", GetHiddenValue);
 }
 

test/parallel/test-util-inspect.js

@@ -2,6 +2,7 @@
 var common = require('../common');
 var assert = require('assert');
 var util = require('util');
+const vm = require('vm');
 
 assert.equal(util.inspect(1), '1');
 assert.equal(util.inspect(false), 'false');
@@ -68,6 +69,35 @@ for (const showHidden of [true, false]) {
                '  y: 1337 }');
 }
 
+// Now do the same checks but from a different context
+for (const showHidden of [true, false]) {
+  const ab = vm.runInNewContext('new ArrayBuffer(4)');
+  const dv = vm.runInNewContext('new DataView(ab, 1, 2)', { ab: ab });
+  assert.equal(util.inspect(ab, showHidden), 'ArrayBuffer { byteLength: 4 }');
+  assert.equal(util.inspect(new DataView(ab, 1, 2), showHidden),
+               'DataView {\n' +
+               '  byteLength: 2,\n' +
+               '  byteOffset: 1,\n' +
+               '  buffer: ArrayBuffer { byteLength: 4 } }');
+  assert.equal(util.inspect(ab, showHidden), 'ArrayBuffer { byteLength: 4 }');
+  assert.equal(util.inspect(dv, showHidden),
+               'DataView {\n' +
+               '  byteLength: 2,\n' +
+               '  byteOffset: 1,\n' +
+               '  buffer: ArrayBuffer { byteLength: 4 } }');
+  ab.x = 42;
+  dv.y = 1337;
+  assert.equal(util.inspect(ab, showHidden),
+               'ArrayBuffer { byteLength: 4, x: 42 }');
+  assert.equal(util.inspect(dv, showHidden),
+               'DataView {\n' +
+               '  byteLength: 2,\n' +
+               '  byteOffset: 1,\n' +
+               '  buffer: ArrayBuffer { byteLength: 4, x: 42 },\n' +
+               '  y: 1337 }');
+}
+
+
 [ Float32Array,
   Float64Array,
   Int16Array,
@@ -94,6 +124,38 @@ for (const showHidden of [true, false]) {
     assert.equal(util.inspect(array, false), `${constructor.name} [ 65, 97 ]`);
   });
 
+// Now check that declaring a TypedArray in a different context works the same
+[ Float32Array,
+  Float64Array,
+  Int16Array,
+  Int32Array,
+  Int8Array,
+  Uint16Array,
+  Uint32Array,
+  Uint8Array,
+  Uint8ClampedArray ].forEach(constructor => {
+    const length = 2;
+    const byteLength = length * constructor.BYTES_PER_ELEMENT;
+    const array = vm.runInNewContext('new constructor(new ArrayBuffer(' +
+                                     'byteLength), 0, length)',
+                                     { constructor: constructor,
+                                       byteLength: byteLength,
+                                       length: length
+                                     });
+    array[0] = 65;
+    array[1] = 97;
+    assert.equal(util.inspect(array, true),
+                 `${constructor.name} [\n` +
+                 `  65,\n` +
+                 `  97,\n` +
+                 `  [BYTES_PER_ELEMENT]: ${constructor.BYTES_PER_ELEMENT},\n` +
+                 `  [length]: ${length},\n` +
+                 `  [byteLength]: ${byteLength},\n` +
+                 `  [byteOffset]: 0,\n` +
+                 `  [buffer]: ArrayBuffer { byteLength: ${byteLength} } ]`);
+    assert.equal(util.inspect(array, false), `${constructor.name} [ 65, 97 ]`);
+  });
+
 // Due to the hash seed randomization it's not deterministic the order that
 // the following ways this hash is displayed.
 // See http://codereview.chromium.org/9124004/