From d1fe6857ba40f895968217d281d79677a9f0d9ae Mon Sep 17 00:00:00 2001
From: Trevor Norris <trev.norris@gmail.com>
Date: Tue, 29 Apr 2014 14:46:58 -0700
Subject: [PATCH] buffer: normalize compare() output

Because of differences in memcmp() implementation, normalize output to
return -1, 0 or 1 only.

Signed-off-by: Timothy J Fontaine <tjfontaine@gmail.com>
---
 src/node_buffer.cc         | 16 ++++++++++++++--
 test/simple/test-buffer.js |  8 ++++----
 2 files changed, 18 insertions(+), 6 deletions(-)

diff --git a/src/node_buffer.cc b/src/node_buffer.cc
index 05d3566ae2b..64f077a6883 100644
--- a/src/node_buffer.cc
+++ b/src/node_buffer.cc
@@ -621,8 +621,20 @@ void Compare(const FunctionCallbackInfo<Value> &args) {
   size_t cmp_length = MIN(obj_a_len, obj_b_len);
 
   int32_t val = memcmp(obj_a_data, obj_b_data, cmp_length);
-  if (!val)
-    val = obj_a_len - obj_b_len;
+
+  // Normalize val to be an integer in the range of [1, -1] since
+  // implementations of memcmp() can vary by platform.
+  if (val == 0) {
+    if (obj_a_len > obj_b_len)
+      val = 1;
+    else if (obj_a_len < obj_b_len)
+      val = -1;
+  } else {
+    if (val > 0)
+      val = 1;
+    else
+      val = -1;
+  }
 
   args.GetReturnValue().Set(val);
 }
diff --git a/test/simple/test-buffer.js b/test/simple/test-buffer.js
index 60c7b7f4422..095551b7dbf 100644
--- a/test/simple/test-buffer.js
+++ b/test/simple/test-buffer.js
@@ -1043,13 +1043,13 @@ var b = new Buffer(1).fill('a');
 var c = new Buffer(1).fill('c');
 var d = new Buffer(2).fill('aa');
 
-assert.equal(b.compare(c), -2);
-assert.equal(c.compare(d), 2);
+assert.equal(b.compare(c), -1);
+assert.equal(c.compare(d), 1);
 assert.equal(d.compare(b), 1);
 assert.equal(b.compare(d), -1);
 
-assert.equal(Buffer.compare(b, c), 2);
-assert.equal(Buffer.compare(c, d), -2);
+assert.equal(Buffer.compare(b, c), 1);
+assert.equal(Buffer.compare(c, d), -1);
 assert.equal(Buffer.compare(d, b), -1);
 assert.equal(Buffer.compare(b, d), 1);