From 25f2a24cdfe93897ba347e75506160c2acb0eb84 Mon Sep 17 00:00:00 2001
From: "David Humphrey (:humph) david.humphrey@senecacollege.ca"
 <david.humphrey@senecacollege.ca>
Date: Wed, 25 Jun 2014 13:13:55 -0400
Subject: [PATCH 1/2] Fix Issue #230: Error: Uncaught TypeError: undefined is
 not a function on <Buffer>.copy()

---
 src/filesystem/implementation.js | 39 ++++++++++++++++++++++++++++++--
 1 file changed, 37 insertions(+), 2 deletions(-)

diff --git a/src/filesystem/implementation.js b/src/filesystem/implementation.js
index 5393e07..8010a68 100644
--- a/src/filesystem/implementation.js
+++ b/src/filesystem/implementation.js
@@ -56,6 +56,27 @@ function standard_check_result_cb(callback) {
   };
 }
 
+/**
+ * Coerce array-like data to Buffer so we can .copy(), etc.
+ * Allow null, a Buffer, or an object that can be dealt with
+ * by the Buffer constructor (e.g., Typed Array, Array, ...)
+ */
+function ensureBuffer(maybeBuffer) {
+  if(!maybeBuffer) {
+    return null;
+  }
+
+  if(Buffer.isBuffer(maybeBuffer)) {
+    return maybeBuffer;
+  }
+
+  try {
+    return new Buffer(maybeBuffer);
+  } catch(e) {
+    return null;
+  }
+}
+
 /**
  * Update node times. Only passed times are modified (undefined times are ignored)
  * and filesystem flags are examined in order to override update logic.
@@ -753,7 +774,10 @@ function write_data(context, ofd, buffer, offset, length, position, callback) {
     if(error) {
       callback(error);
     } else {
-      fileData = result;
+      fileData = ensureBuffer(result);
+      if(!fileData) {
+        return callback(new Errors.EIO('Expected Buffer'));
+      }
       var _position = (!(undefined === position || null === position)) ? position : ofd.position;
       var newSize = Math.max(fileData.length, _position + length);
       var newData = new Buffer(newSize);
@@ -793,7 +817,10 @@ function read_data(context, ofd, buffer, offset, length, position, callback) {
     if(error) {
       callback(error);
     } else {
-      fileData = result;
+      fileData = ensureBuffer(result);
+      if(!fileData) {
+        return callback(new Errors.EIO('Expected Buffer'));
+      }
       var _position = (!(undefined === position || null === position)) ? position : ofd.position;
       length = (_position + length > buffer.length) ? length - _position : length;
       fileData.copy(buffer, offset, _position, _position + length);
@@ -1180,6 +1207,10 @@ function truncate_file(context, path, length, callback) {
     if (error) {
       callback(error);
     } else {
+      fileData = ensureBuffer(fileData);
+      if(!fileData) {
+        return callback(new Errors.EIO('Expected Buffer'));
+      }
       var data = new Buffer(length);
       data.fill(0);
       if(fileData) {
@@ -1234,6 +1265,10 @@ function ftruncate_file(context, ofd, length, callback) {
       callback(error);
     } else {
       var data;
+      fileData = ensureBuffer(fileData);
+      if(!fileData) {
+        return callback(new Errors.EIO('Expected Buffer'));
+      }
       if(fileData) {
         data = fileData.slice(0, length);
       } else {

From 76526caa3568fe94126a30b4c48b490169c24ee1 Mon Sep 17 00:00:00 2001
From: "David Humphrey (:humph) david.humphrey@senecacollege.ca"
 <david.humphrey@senecacollege.ca>
Date: Wed, 25 Jun 2014 13:51:07 -0400
Subject: [PATCH 2/2] Add a clarifying comment about not coercing buffers
 passed to read operations.

---
 src/filesystem/implementation.js | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/src/filesystem/implementation.js b/src/filesystem/implementation.js
index 8010a68..4744428 100644
--- a/src/filesystem/implementation.js
+++ b/src/filesystem/implementation.js
@@ -60,6 +60,12 @@ function standard_check_result_cb(callback) {
  * Coerce array-like data to Buffer so we can .copy(), etc.
  * Allow null, a Buffer, or an object that can be dealt with
  * by the Buffer constructor (e.g., Typed Array, Array, ...)
+ *
+ * WARNING: be very careful not to call this on parameters of
+ * API methods that pass storage (like read). You don't want to
+ * overwrite a buffer that a caller is holding a reference to,
+ * and expects to be filled via the read. If the caller passes
+ * in a non-Buffer, we should throw instead of coerce.
  */
 function ensureBuffer(maybeBuffer) {
   if(!maybeBuffer) {