From eddea815e37fd69efc4dc52da0ede25363145fd2 Mon Sep 17 00:00:00 2001
From: Connor Peet <connor@peet.io>
Date: Sun, 22 Mar 2015 20:45:16 -0400
Subject: [PATCH 1/4] Check input to util.inherits

---
 lib/util.js                | 10 ++++++++++
 test/parallel/test-util.js |  7 +++++++
 2 files changed, 17 insertions(+)

diff --git a/lib/util.js b/lib/util.js
index fb5f7f4b31ab3d..e4dd64521b7c27 100644
--- a/lib/util.js
+++ b/lib/util.js
@@ -616,8 +616,18 @@ exports.log = function() {
  * @param {function} ctor Constructor function which needs to inherit the
  *     prototype.
  * @param {function} superCtor Constructor function to inherit prototype from.
+ * @throws {TypeError} Will error if either constructor is null, or if
+ *     the super constructor lacks a prototype.
  */
 exports.inherits = function(ctor, superCtor) {
+
+  if (isNullOrUndefined(ctor))
+    throw new TypeError('The constructor to `inherits` must not be null.');
+  if (isNullOrUndefined(superCtor))
+    throw new TypeError('The super constructor to `inherits` must not be null.');
+  if (isNullOrUndefined(superCtor.prototype))
+    throw new TypeError('The super constructor must have a prototype.');
+
   ctor.super_ = superCtor;
   ctor.prototype = Object.create(superCtor.prototype, {
     constructor: {
diff --git a/test/parallel/test-util.js b/test/parallel/test-util.js
index 2fb4bc5609bcd6..03456d64393842 100644
--- a/test/parallel/test-util.js
+++ b/test/parallel/test-util.js
@@ -78,3 +78,10 @@ assert.deepEqual(util._extend({a:1}, true),       {a:1});
 assert.deepEqual(util._extend({a:1}, false),      {a:1});
 assert.deepEqual(util._extend({a:1}, {b:2}),      {a:1, b:2});
 assert.deepEqual(util._extend({a:1, b:2}, {b:3}), {a:1, b:3});
+
+// inherits
+var ctor = function() {};
+assert.throws(function() { util.inherits(ctor, {}) }, TypeError);
+assert.throws(function() { util.inherits(ctor, null) }, TypeError);
+assert.throws(function() { util.inherits(null, ctor) }, TypeError);
+assert.doesNotThrow(function() { util.inherits(ctor, ctor) }, TypeError);

From e92728884ddddc85cf973092dd038afe3c693ec0 Mon Sep 17 00:00:00 2001
From: Connor Peet <connor@peet.io>
Date: Sun, 22 Mar 2015 20:49:23 -0400
Subject: [PATCH 2/4] Prototype is allowed to be null, just not undefined

---
 lib/util.js | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/lib/util.js b/lib/util.js
index e4dd64521b7c27..116e5e89d72c7a 100644
--- a/lib/util.js
+++ b/lib/util.js
@@ -625,7 +625,7 @@ exports.inherits = function(ctor, superCtor) {
     throw new TypeError('The constructor to `inherits` must not be null.');
   if (isNullOrUndefined(superCtor))
     throw new TypeError('The super constructor to `inherits` must not be null.');
-  if (isNullOrUndefined(superCtor.prototype))
+  if (isUndefined(superCtor.prototype))
     throw new TypeError('The super constructor must have a prototype.');
 
   ctor.super_ = superCtor;

From 7131380bde82c61a8008895fa1932427b02fef8c Mon Sep 17 00:00:00 2001
From: Connor Peet <connor@peet.io>
Date: Sun, 22 Mar 2015 22:54:33 -0400
Subject: [PATCH 3/4] Use manual checks

---
 lib/util.js | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/lib/util.js b/lib/util.js
index 116e5e89d72c7a..42de70419472b5 100644
--- a/lib/util.js
+++ b/lib/util.js
@@ -621,11 +621,11 @@ exports.log = function() {
  */
 exports.inherits = function(ctor, superCtor) {
 
-  if (isNullOrUndefined(ctor))
+  if (ctor === undefined || ctor === null)
     throw new TypeError('The constructor to `inherits` must not be null.');
-  if (isNullOrUndefined(superCtor))
+  if (superCtor === undefined || superCtor === null)
     throw new TypeError('The super constructor to `inherits` must not be null.');
-  if (isUndefined(superCtor.prototype))
+  if (superCtor.prototype === undefined)
     throw new TypeError('The super constructor must have a prototype.');
 
   ctor.super_ = superCtor;

From f32b4027298a34e106900dd1342ef5983376b2d4 Mon Sep 17 00:00:00 2001
From: Connor Peet <connor@peet.io>
Date: Sun, 22 Mar 2015 23:03:21 -0400
Subject: [PATCH 4/4] Line length

---
 lib/util.js | 11 ++++++++---
 1 file changed, 8 insertions(+), 3 deletions(-)

diff --git a/lib/util.js b/lib/util.js
index 42de70419472b5..69c46e6ea7a9fb 100644
--- a/lib/util.js
+++ b/lib/util.js
@@ -622,11 +622,16 @@ exports.log = function() {
 exports.inherits = function(ctor, superCtor) {
 
   if (ctor === undefined || ctor === null)
-    throw new TypeError('The constructor to `inherits` must not be null.');
+    throw new TypeError('The constructor to `inherits` must not be ' +
+                        'null or undefined.');
+
   if (superCtor === undefined || superCtor === null)
-    throw new TypeError('The super constructor to `inherits` must not be null.');
+    throw new TypeError('The super constructor to `inherits` must not ' +
+                        'be null or undefined.');
+
   if (superCtor.prototype === undefined)
-    throw new TypeError('The super constructor must have a prototype.');
+    throw new TypeError('The super constructor to `inherits` must ' +
+                        'have a prototype.');
 
   ctor.super_ = superCtor;
   ctor.prototype = Object.create(superCtor.prototype, {