From 05e2acb428047174fc201158ac859d20c2ece1dd Mon Sep 17 00:00:00 2001
From: Justin Sprigg <IPWNDYOU@gmail.com>
Date: Mon, 16 May 2016 02:04:03 +1000
Subject: [PATCH] buffer: fix single digit hex string handling

Fixes single digit hex strings not raising TypeError on Buffer creation.

Fixes: https://github.com/nodejs/node/issues/6770
PR-URL: https://github.com/nodejs/node/pull/6775
Reviewed-By: Anna Henningsen <anna@addaleax.net>
---
 lib/buffer.js                | 6 +++---
 test/parallel/test-buffer.js | 9 +++++++++
 2 files changed, 12 insertions(+), 3 deletions(-)

diff --git a/lib/buffer.js b/lib/buffer.js
index 515f841fd3..a4bd2a2f87 100644
--- a/lib/buffer.js
+++ b/lib/buffer.js
@@ -225,11 +225,11 @@ function fromString(string, encoding) {
   if (!Buffer.isEncoding(encoding))
     throw new TypeError('"encoding" must be a valid string encoding');
 
-  var length = byteLength(string, encoding);
-
-  if (length === 0)
+  if (string.length === 0)
     return Buffer.alloc(0);
 
+  var length = byteLength(string, encoding);
+
   if (length >= (Buffer.poolSize >>> 1))
     return binding.createFromString(string, encoding);
 
diff --git a/test/parallel/test-buffer.js b/test/parallel/test-buffer.js
index 62fd488efe..f48cfc2a32 100644
--- a/test/parallel/test-buffer.js
+++ b/test/parallel/test-buffer.js
@@ -749,6 +749,15 @@ for (let i = 0; i < 256; i++) {
   assert.equal(hexb2[i], hexb[i]);
 }
 
+// Test single hex character throws TypeError
+// - https://github.com/nodejs/node/issues/6770
+assert.throws(function() {
+  Buffer.from('A', 'hex');
+}, TypeError);
+
+// Test single base64 char encodes as 0
+assert.strictEqual(Buffer.from('A', 'base64').length, 0);
+
 {
   // test an invalid slice end.
   console.log('Try to slice off the end of the buffer');