assert: Check typed array view type in deepEqual

Do not convert typed arrays to `Buffer` for deepEqual since
their values may not be accurately represented by 8-bit ints.
Instead perform binary comparison of underlying `ArrayBuffer`s,
but only when the array types match.

Never apply any kind of optimization for floating-point typed
arrays since bit pattern equality is not the right kind of check
for them.

PR-URL: https://github.com/nodejs/node/pull/5910
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Fixes: https://github.com/nodejs/node/issues/5907

1 files changed, 13 insertions, 4 deletions

diff --git a/lib/assert.js b/lib/assert.js
index 61aba557ec..b4de551e28 100644
--- a/lib/assert.js
+++ b/lib/assert.js
@@ -29,6 +29,7 @@ const compare = process.binding('buffer').compare;
 const util = require('util');
 const Buffer = require('buffer').Buffer;
 const pSlice = Array.prototype.slice;
+const pToString = (obj) => Object.prototype.toString.call(obj);
 
 // 1. The assert module provides functions that throw
 // AssertionError's when particular conditions are not met. The
@@ -170,10 +171,18 @@ function _deepEqual(actual, expected, strict) {
              (expected === null || typeof expected !== 'object')) {
     return strict ? actual === expected : actual == expected;
 
-  // If both values are instances of typed arrays, wrap them in
-  // a Buffer each to increase performance
-  } else if (ArrayBuffer.isView(actual) && ArrayBuffer.isView(expected)) {
-    return compare(Buffer.from(actual), Buffer.from(expected)) === 0;
+  // If both values are instances of typed arrays, wrap their underlying
+  // ArrayBuffers in a Buffer each to increase performance
+  // This optimization requires the arrays to have the same type as checked by
+  // Object.prototype.toString (aka pToString). Never perform binary
+  // comparisons for Float*Arrays, though, since e.g. +0 === -0 but their
+  // bit patterns are not identical.
+  } else if (ArrayBuffer.isView(actual) && ArrayBuffer.isView(expected) &&
+             pToString(actual) === pToString(expected) &&
+             !(actual instanceof Float32Array ||
+               actual instanceof Float64Array)) {
+    return compare(Buffer.from(actual.buffer),
+                   Buffer.from(expected.buffer)) === 0;
 
   // 7.5 For all other Object pairs, including Array objects, equivalence is
   // determined by having the same number of owned properties (as verified