From 16bbeccd40a9d08f7ae73eeeefa0fd6f206dc7a9 Mon Sep 17 00:00:00 2001
From: Trevor Norris <trev.norris@gmail.com>
Date: Tue, 22 Jan 2013 09:09:12 -0800
Subject: [PATCH] buffer: slow buffer copy compatibility fix

Fix issue where SlowBuffers couldn't be passed as target to Buffer
copy().

Also included checks to see if Argument parameters are defined before
assigning their values. This offered ~3x's performance gain.
---
 lib/buffer.js              | 4 ++--
 src/node_buffer.cc         | 8 ++++----
 test/simple/test-buffer.js | 8 ++++++++
 3 files changed, 14 insertions(+), 6 deletions(-)

diff --git a/lib/buffer.js b/lib/buffer.js
index d605829d73..098406bc46 100644
--- a/lib/buffer.js
+++ b/lib/buffer.js
@@ -573,8 +573,8 @@ Buffer.prototype.copy = function(target, target_start, start, end) {
     end = target.length - target_start + start;
   }
 
-  return this.parent.copy(target.parent,
-                          target_start + target.offset,
+  return this.parent.copy(target.parent || target,
+                          target_start + (target.offset || 0),
                           start + this.offset,
                           end + this.offset);
 };
diff --git a/src/node_buffer.cc b/src/node_buffer.cc
index 70c9c80876..d808dbf978 100644
--- a/src/node_buffer.cc
+++ b/src/node_buffer.cc
@@ -402,10 +402,10 @@ Handle<Value> Buffer::Copy(const Arguments &args) {
   Local<Object> target = args[0]->ToObject();
   char* target_data = Buffer::Data(target);
   size_t target_length = Buffer::Length(target);
-  size_t target_start = args[1]->Uint32Value();
-  size_t source_start = args[2]->Uint32Value();
-  size_t source_end = args[3]->IsUint32() ? args[3]->Uint32Value()
-                                          : source->length_;
+  size_t target_start = args[1]->IsUndefined() ? 0 : args[1]->Uint32Value();
+  size_t source_start = args[2]->IsUndefined() ? 0 : args[2]->Uint32Value();
+  size_t source_end = args[3]->IsUndefined() ? source->length_
+                                              : args[3]->Uint32Value();
 
   if (source_end < source_start) {
     return ThrowException(Exception::Error(String::New(
diff --git a/test/simple/test-buffer.js b/test/simple/test-buffer.js
index e221a53e0b..387973d936 100644
--- a/test/simple/test-buffer.js
+++ b/test/simple/test-buffer.js
@@ -85,6 +85,14 @@ for (var i = 0; i < c.length; i++) {
   assert.equal(i % 256, c[i]);
 }
 
+// copy from fast to slow buffer
+var sb = new SlowBuffer(b.length);
+var copied = b.copy(sb);
+console.log('copied %d bytes from b into sb');
+for (var i = 0; i < sb.length; i++) {
+  assert.strictEqual(sb[i], b[i]);
+}
+
 var caught_error = null;
 
 // try to copy from before the beginning of b