From ad5e1452904c791fea873fac002e6256230177a0 Mon Sep 17 00:00:00 2001
From: James M Snell <jasnell@gmail.com>
Date: Thu, 17 Mar 2016 10:35:11 -0700
Subject: [PATCH] buffer: backport new buffer constructor APIs

This backports the new `Buffer.alloc()`, `Buffer.allocUnsafe()`,
and `Buffer.from()` APIs for v5.

Also included in this backport is the change that allows fill('')
to zero-fill (as opposed to doing nothing) and the additional
`byteOffset` and `length` arguments for `Buffer(arrayBuffer)` and
`Buffer.from(arrayBuffer)`.

This backport includes the new test cases.

This backport *does not* update all of the internal uses of the
existing `Buffer()` constructor.

This backport also *does not* include the soft deprecation of the
existing `Buffer()` constructor.
---
 doc/api/buffer.markdown                  |  484 ++++++--
 lib/buffer.js                            |  127 +-
 src/node_buffer.cc                       |   15 +-
 test/parallel/test-buffer-alloc.js       | 1431 ++++++++++++++++++++++
 test/parallel/test-buffer-safe-unsafe.js |   14 +
 5 files changed, 1951 insertions(+), 120 deletions(-)
 create mode 100644 test/parallel/test-buffer-alloc.js
 create mode 100644 test/parallel/test-buffer-safe-unsafe.js

diff --git a/doc/api/buffer.markdown b/doc/api/buffer.markdown
index 4c8a48de906508..cad33d897b9c21 100644
--- a/doc/api/buffer.markdown
+++ b/doc/api/buffer.markdown
@@ -20,20 +20,97 @@ resized.
 The `Buffer` class is a global within Node.js, making it unlikely that one
 would need to ever use `require('buffer')`.
 
+
 ```js
-const buf1 = new Buffer(10);
-  // creates a buffer of length 10
+const buf1 = Buffer.alloc(10);
+  // Creates a zero-filled Buffer of length 10.
+
+const buf2 = Buffer.alloc(10, 1);
+  // Creates a Buffer of length 10, filled with 0x01.
+
+const buf3 = Buffer.allocUnsafe(10);
+  // Creates an uninitialized buffer of length 10.
+  // This is faster than calling Buffer.alloc() but the returned
+  // Buffer instance might contain old data that needs to be
+  // overwritten using either fill() or write().
 
-const buf2 = new Buffer([1,2,3]);
-  // creates a buffer containing [01, 02, 03]
+const buf4 = Buffer.from([1,2,3]);
+  // Creates a Buffer containing [01, 02, 03].
 
-const buf3 = new Buffer('test');
-  // creates a buffer containing ASCII bytes [74, 65, 73, 74]
+const buf5 = Buffer.from('test');
+  // Creates a Buffer containing ASCII bytes [74, 65, 73, 74].
 
-const buf4 = new Buffer('tést', 'utf8');
-  // creates a buffer containing UTF8 bytes [74, c3, a9, 73, 74]
+const buf6 = Buffer.from('tést', 'utf8');
+  // Creates a Buffer containing UTF8 bytes [74, c3, a9, 73, 74].
 ```
 
+## `Buffer.from()`, `Buffer.alloc()`, and `Buffer.allocUnsafe()`
+
+Historically, `Buffer` instances have been created using the `Buffer` 
+constructor function, which allocates the returned `Buffer`
+differently based on what arguments are provided:
+
+* Passing a number as the first argument to `Buffer()` (e.g. `new Buffer(10)`),
+  allocates a new `Buffer` object of the specified size. The memory allocated
+  for such `Buffer` instances is *not* initialized and *can contain sensitive
+  data*. Such `Buffer` objects *must* be initialized *manually* by using either
+  [`buf.fill(0)`][] or by writing to the `Buffer` completely. While this
+  behavior is *intentional* to improve performance, development experience has
+  demonstrated that a more explicit distinction is required between creating a
+  fast-but-uninitialized `Buffer` versus creating a slower-but-safer `Buffer`.
+* Passing a string, array, or `Buffer` as the first argument copies the
+  passed object's data into the `Buffer`.
+* Passing an `ArrayBuffer` returns a `Buffer` that shares allocated memory with
+  the given `ArrayBuffer`.
+
+Because the behavior of `new Buffer()` changes significantly based on the type
+of value passed as the first argument, applications that do not properly
+validate the input arguments passed to `new Buffer()`, or that fail to
+appropriately initialize newly allocated `Buffer` content, can inadvertently
+introduce security and reliability issues into their code.
+
+To make the creation of `Buffer` objects more reliable and less error prone,
+new `Buffer.from()`, `Buffer.alloc()`, and `Buffer.allocUnsafe()` methods have
+been introduced as an alternative means of creating `Buffer` instances.
+
+*Developers should migrate all existing uses of the `new Buffer()` constructors
+to one of these new APIs.*
+
+* [`Buffer.from(array)`][buffer_from_array] returns a new `Buffer` containing
+  a *copy* of the provided octets.
+* [`Buffer.from(arrayBuffer[, byteOffset [, length]])`][buffer_from_arraybuf]
+  returns a new `Buffer` that *shares* the same allocated memory as the given
+  `ArrayBuffer`.
+* [`Buffer.from(buffer)`][buffer_from_buffer] returns a new `Buffer`
+  containing a *copy* of the contents of the given `Buffer`.
+* [`Buffer.from(str[, encoding])`][buffer_from_string] returns a new `Buffer`
+  containing a *copy* of the provided string.
+* [`Buffer.alloc(size[, fill[, encoding]])`][buffer_alloc] returns a "filled"
+  `Buffer` instance of the specified size. This method can be significantly
+  slower than [`Buffer.allocUnsafe(size)`][buffer_allocunsafe] but ensures that
+  newly created `Buffer` instances never contain old and potentially sensitive
+  data.
+* [`Buffer.allocUnsafe(size)`][buffer_allocunsafe] returns a new `Buffer` of
+  the specified `size` whose content *must* be initialized using either
+  [`buf.fill(0)`][] or written to completely.
+
+`Buffer` instances returned by `Buffer.allocUnsafe(size)` *may* be allocated
+off a shared internal memory pool if the `size` is less than or equal to half
+`Buffer.poolSize`.
+
+### What makes `Buffer.allocUnsafe(size)` "unsafe"?
+
+When calling `Buffer.allocUnsafe()`, the segment of allocated memory is
+*uninitialized* (it is not zeroed-out). While this design makes the allocation
+of memory quite fast, the allocated segment of memory might contain old data
+that is potentially sensitive. Using a `Buffer` created by
+`Buffer.allocUnsafe(size)` without *completely* overwriting the memory can
+allow this old data to be leaked when the `Buffer` memory is read.
+
+While there are clear performance advantages to using `Buffer.allocUnsafe()`,
+extra care *must* be taken in order to avoid introducing security
+vulnerabilities into an application.
+
 ## Buffers and Character Encodings
 
 Buffers are commonly used to represent sequences of encoded characters
@@ -42,7 +119,7 @@ convert back and forth between Buffers and ordinary JavaScript string objects
 by using an explicit encoding method.
 
 ```js
-const buf = new Buffer('hello world', 'ascii');
+const buf = Buffer.from('hello world', 'ascii');
 console.log(buf.toString('hex'));
   // prints: 68656c6c6f20776f726c64
 console.log(buf.toString('base64'));
@@ -83,24 +160,24 @@ existing Buffer without copying, making `Buffer#slice()` far more efficient.
 It is also possible to create new TypedArray instances from a `Buffer` with the
 following caveats:
 
-1. The Buffer instances's memory is copied to the TypedArray, not shared.
+1. The `Buffer` object's memory is copied to the TypedArray, not shared.
 
-2. The Buffer's memory is interpreted as an array of distinct elements, and not
-as a byte array of the target type. That is,
-`new Uint32Array(new Buffer([1,2,3,4]))` creates a 4-element `Uint32Array`
+2. The `Buffer` object's memory is interpreted as an array of distinct
+   elements, and not as a byte array of the target type. That is,
+   `new Uint32Array(Buffer.from([1,2,3,4]))` creates a 4-element `Uint32Array`
    with elements `[1,2,3,4]`, not a `Uint32Array` with a single element
    `[0x1020304]` or `[0x4030201]`.
 
-It is possible to create a new Buffer that shares the same allocated memory as
-a TypedArray instance by using the TypeArray objects `.buffer` property:
+It is possible to create a new `Buffer` that shares the same allocated memory as
+a TypedArray instance by using the TypeArray object's `.buffer` property:
 
 ```js
 const arr = new Uint16Array(2);
 arr[0] = 5000;
 arr[1] = 4000;
 
-const buf1 = new Buffer(arr); // copies the buffer
-const buf2 = new Buffer(arr.buffer); // shares the memory with arr;
+const buf1 = Buffer.from(arr); // copies the buffer
+const buf2 = Buffer.from(arr.buffer); // shares the memory with arr;
 
 console.log(buf1);
   // Prints: <Buffer 88 a0>, copied buffer has only two elements
@@ -114,24 +191,38 @@ console.log(buf2);
   // Prints: <Buffer 88 13 70 17>
 ```
 
-Note that when creating a Buffer using the TypeArray's `.buffer`, it is not
-currently possible to use only a portion of the underlying `ArrayBuffer`. To
-create a Buffer that uses only a part of the `ArrayBuffer`, use the
-[`buf.slice()`][] function after the Buffer is created:
+Note that when creating a `Buffer` using the TypedArray's `.buffer`, it is
+possible to use only a portion of the underlying `ArrayBuffer` by passing in
+`byteOffset` and `length` parameters:
 
 ```js
 const arr = new Uint16Array(20);
-const buf = new Buffer(arr.buffer).slice(0, 16);
+const buf = Buffer.from(arr.buffer, 0, 16);
 console.log(buf.length);
   // Prints: 16
 ```
 
+The `Buffer.from()` and [`TypedArray.from()`][] (e.g.`Uint8Array.from()`) have
+different signatures and implementations. Specifically, the TypedArray variants
+accept a second argument that is a mapping function that is invoked on every
+element of the typed array:
+
+* `TypedArray.from(source[, mapFn[, thisArg]])`
+
+The `Buffer.from()` method, however, does not support the use of a mapping
+function:
+
+* [`Buffer.from(array)`][buffer_from_array]
+* [`Buffer.from(buffer)`][buffer_from_buffer]
+* [`Buffer.from(arrayBuffer[, byteOffset [, length]])`][buffer_from_arraybuf]
+* [`Buffer.from(str[, encoding])`][buffer_from_string]
+
 ## Buffers and ES6 iteration
 
 Buffers can be iterated over using the ECMAScript 2015 (ES6) `for..of` syntax:
 
 ```js
-const buf = new Buffer([1, 2, 3]);
+const buf = Buffer(.from[1, 2, 3]);
 
 for (var b of buf)
   console.log(b)
@@ -179,15 +270,20 @@ console.log(buf2.toString());
   // 'buffer' (copy is not changed)
 ```
 
-### new Buffer(arrayBuffer)
+### new Buffer(arrayBuffer[, byteOffset[, length]])
 
 * `arrayBuffer` - The `.buffer` property of a `TypedArray` or a `new
   ArrayBuffer()`
+* `byteOffset` {Number} Default: `0`
+* `length` {Number} Default: `arrayBuffer.length - byteOffset`
 
 When passed a reference to the `.buffer` property of a `TypedArray` instance,
 the newly created Buffer will share the same allocated memory as the
 TypedArray.
 
+The optional `byteOffset` and `length` arguments specify a memory range within
+the `arrayBuffer` that will be shared by the `Buffer`.
+
 ```js
 const arr = new Uint16Array(2);
 arr[0] = 5000;
@@ -209,16 +305,16 @@ console.log(buf);
 
 * `size` {Number}
 
-Allocates a new Buffer of `size` bytes.  The `size` must be less than
+Allocates a new `Buffer` of `size` bytes.  The `size` must be less than
 or equal to the value of `require('buffer').kMaxLength` (on 64-bit
 architectures, `kMaxLength` is `(2^31)-1`). Otherwise, a [`RangeError`][] is
 thrown. If a `size` less than 0 is specified, a zero-length Buffer will be
 created.
 
-Unlike `ArrayBuffers`, the underlying memory for Buffer instances created in
-this way is not initialized. The contents of a newly created `Buffer` are
-unknown and could contain sensitive data. Use [`buf.fill(0)`][] to initialize a
-Buffer to zeroes.
+Unlike `ArrayBuffers`, the underlying memory for `Buffer` instances created in
+this way is *not initialized*. The contents of a newly created `Buffer` are
+unknown and *could contain sensitive data*. Use [`buf.fill(0)`][] to initialize 
+a Buffer to zeroes.
 
 ```js
 const buf = new Buffer(5);
@@ -250,6 +346,92 @@ console.log(buf2.toString());
   // prints: this is a tést
 ```
 
+### Class Method: Buffer.alloc(size[, fill[, encoding]])
+
+* `size` {Number}
+* `fill` {Value} Default: `undefined`
+* `encoding` {String} Default: `utf8`
+
+Allocates a new `Buffer` of `size` bytes. If `fill` is `undefined`, the
+`Buffer` will be *zero-filled*.
+
+```js
+const buf = Buffer.alloc(5);
+console.log(buf);
+  // <Buffer 00 00 00 00 00>
+```
+
+The `size` must be less than or equal to the value of
+`require('buffer').kMaxLength` (on 64-bit architectures, `kMaxLength` is
+`(2^31)-1`). Otherwise, a [`RangeError`][] is thrown. If a `size` less than 0
+is specified, a zero-length `Buffer` will be created.
+
+If `fill` is specified, the allocated `Buffer` will be initialized by calling
+`buf.fill(fill)`. See [`buf.fill()`][] for more information.
+
+```js
+const buf = Buffer.alloc(5, 'a');
+console.log(buf);
+  // <Buffer 61 61 61 61 61>
+```
+
+If both `fill` and `encoding` are specified, the allocated `Buffer` will be
+initialized by calling `buf.fill(fill, encoding)`. For example:
+
+```js
+const buf = Buffer.alloc(11, 'aGVsbG8gd29ybGQ=', 'base64');
+console.log(buf);
+  // <Buffer 68 65 6c 6c 6f 20 77 6f 72 6c 64>
+```
+
+Calling `Buffer.alloc(size)` can be significantly slower than the alternative
+`Buffer.allocUnsafe(size)` but ensures that the newly created `Buffer` instance
+contents will *never contain sensitive data*.
+
+A `TypeError` will be thrown if `size` is not a number.
+
+### Class Method: Buffer.allocUnsafe(size)
+
+* `size` {Number}
+
+Allocates a new *non-zero-filled* `Buffer` of `size` bytes.  The `size` must
+be less than or equal to the value of `require('buffer').kMaxLength` (on 64-bit
+architectures, `kMaxLength` is `(2^31)-1`). Otherwise, a [`RangeError`][] is
+thrown. If a `size` less than 0 is specified, a zero-length `Buffer` will be
+created.
+
+The underlying memory for `Buffer` instances created in this way is *not
+initialized*. The contents of the newly created `Buffer` are unknown and
+*may contain sensitive data*. Use [`buf.fill(0)`][] to initialize such
+`Buffer` instances to zeroes.
+
+```js
+const buf = Buffer.allocUnsafe(5);
+console.log(buf);
+  // <Buffer 78 e0 82 02 01>
+  // (octets will be different, every time)
+buf.fill(0);
+console.log(buf);
+  // <Buffer 00 00 00 00 00>
+```
+
+A `TypeError` will be thrown if `size` is not a number.
+
+Note that the `Buffer` module pre-allocates an internal `Buffer` instance of
+size `Buffer.poolSize` that is used as a pool for the fast allocation of new
+`Buffer` instances created using `Buffer.allocUnsafe(size)` (and the
+`new Buffer(size)` constructor) only when `size` is less than or equal to
+`Buffer.poolSize >> 1` (floor of `Buffer.poolSize` divided by two). The default
+value of `Buffer.poolSize` is `8192` but can be modified.
+
+Use of this pre-allocated internal memory pool is a key difference between
+calling `Buffer.alloc(size, fill)` vs. `Buffer.allocUnsafe(size).fill(fill)`.
+Specifically, `Buffer.alloc(size, fill)` will *never* use the internal Buffer
+pool, while `Buffer.allocUnsafe(size).fill(fill)` *will* use the internal
+Buffer pool if `size` is less than or equal to half `Buffer.poolSize`. The
+difference is subtle but can be important when an application requires the
+additional performance that `Buffer.allocUnsafe(size)` provides.
+
 ### Class Method: Buffer.byteLength(string[, encoding])
 
 * `string` {String}
@@ -281,7 +463,7 @@ Compares `buf1` to `buf2` typically for the purpose of sorting arrays of
 Buffers. This is equivalent is calling [`buf1.compare(buf2)`][].
 
 ```js
-const arr = [Buffer('1234'), Buffer('0123')];
+const arr = [Buffer.from('1234'), Buffer.from('0123')];
 arr.sort(Buffer.compare);
 ```
 
@@ -304,9 +486,9 @@ to provide the length explicitly.
 Example: build a single Buffer from a list of three Buffers:
 
 ```js
-const buf1 = new Buffer(10).fill(0);
-const buf2 = new Buffer(14).fill(0);
-const buf3 = new Buffer(18).fill(0);
+const buf1 = Buffer.alloc(10, 0);
+const buf2 = Buffer.alloc(14, 0);
+const buf3 = Buffer.alloc(18, 0);
 const totalLength = buf1.length + buf2.length + buf3.length;
 
 console.log(totalLength);
@@ -319,6 +501,102 @@ console.log(bufA.length);
 // 42
 ```
 
+### Class Method: Buffer.from(array)
+
+* `array` {Array}
+
+Allocates a new `Buffer` using an `array` of octets.
+
+```js
+const buf = Buffer.from([0x62,0x75,0x66,0x66,0x65,0x72]);
+  // creates a new Buffer containing ASCII bytes
+  // ['b','u','f','f','e','r']
+```
+
+A `TypeError` will be thrown if `array` is not an `Array`.
+
+### Class Method: Buffer.from(arrayBuffer[, byteOffset[, length]])
+
+* `arrayBuffer` {ArrayBuffer} The `.buffer` property of a `TypedArray` or
+  a `new ArrayBuffer()`
+* `byteOffset` {Number} Default: `0`
+* `length` {Number} Default: `arrayBuffer.length - byteOffset`
+
+When passed a reference to the `.buffer` property of a `TypedArray` instance,
+the newly created `Buffer` will share the same allocated memory as the
+TypedArray.
+
+```js
+const arr = new Uint16Array(2);
+arr[0] = 5000;
+arr[1] = 4000;
+
+const buf = Buffer.from(arr.buffer); // shares the memory with arr;
+
+console.log(buf);
+  // Prints: <Buffer 88 13 a0 0f>
+
+// changing the TypedArray changes the Buffer also
+arr[1] = 6000;
+
+console.log(buf);
+  // Prints: <Buffer 88 13 70 17>
+```
+
+The optional `byteOffset` and `length` arguments specify a memory range within
+the `arrayBuffer` that will be shared by the `Buffer`.
+
+```js
+const ab = new ArrayBuffer(10);
+const buf = Buffer.from(ab, 0, 2);
+console.log(buf.length);
+  // Prints: 2
+```
+
+A `TypeError` will be thrown if `arrayBuffer` is not an `ArrayBuffer`.
+
+### Class Method: Buffer.from(buffer)
+
+* `buffer` {Buffer}
+
+Copies the passed `buffer` data onto a new `Buffer` instance.
+
+```js
+const buf1 = Buffer.from('buffer');
+const buf2 = Buffer.from(buf1);
+
+buf1[0] = 0x61;
+console.log(buf1.toString());
+  // 'auffer'
+console.log(buf2.toString());
+  // 'buffer' (copy is not changed)
+```
+
+A `TypeError` will be thrown if `buffer` is not a `Buffer`.
+
+### Class Method: Buffer.from(str[, encoding])
+
+* `str` {String} String to encode.
+* `encoding` {String} Encoding to use, Default: `'utf8'`
+
+Creates a new `Buffer` containing the given JavaScript string `str`. If
+provided, the `encoding` parameter identifies the character encoding.
+If not provided, `encoding` defaults to `'utf8'`.
+
+```js
+const buf1 = Buffer.from('this is a tést');
+console.log(buf1.toString());
+  // prints: this is a tést
+console.log(buf1.toString('ascii'));
+  // prints: this is a tC)st
+
+const buf2 = Buffer.from('7468697320697320612074c3a97374', 'hex');
+console.log(buf2.toString());
+  // prints: this is a tést
+```
+
+A `TypeError` will be thrown if `str` is not a string.
+
 ### Class Method: Buffer.isBuffer(obj)
 
 * `obj` {Object}
@@ -347,7 +625,7 @@ Example: copy an ASCII string into a Buffer, one byte at a time:
 
 ```js
 const str = "Node.js";
-const buf = new Buffer(str.length);
+const buf = Buffer.allocUnsafe(str.length);
 
 for (var i = 0; i < str.length ; i++) {
   buf[i] = str.charCodeAt(i);
@@ -371,9 +649,9 @@ Comparison is based on the actual sequence of bytes in each Buffer.
 * `-1` is returned if `otherBuffer` should come *after* `buf` when sorted.
 
 ```js
-const buf1 = new Buffer('ABC');
-const buf2 = new Buffer('BCD');
-const buf3 = new Buffer('ABCD');
+const buf1 = Buffer.from('ABC');
+const buf2 = Buffer.from('BCD');
+const buf3 = Buffer.from('ABCD');
 
 console.log(buf1.compare(buf1));
   // Prints: 0
@@ -405,8 +683,8 @@ Example: build two Buffers, then copy `buf1` from byte 16 through byte 19
 into `buf2`, starting at the 8th byte in `buf2`.
 
 ```js
-const buf1 = new Buffer(26);
-const buf2 = new Buffer(26).fill('!');
+const buf1 = Buffer.allocUnsafe(26);
+const buf2 = Buffer.allocUnsafe(26).fill('!');
 
 for (var i = 0 ; i < 26 ; i++) {
   buf1[i] = i + 97; // 97 is ASCII a
@@ -421,7 +699,7 @@ Example: Build a single Buffer, then copy data from one region to an overlapping
 region in the same Buffer
 
 ```js
-const buf = new Buffer(26);
+const buf = Buffer.allocUnsafe(26);
 
 for (var i = 0 ; i < 26 ; i++) {
   buf[i] = i + 97; // 97 is ASCII a
@@ -441,7 +719,7 @@ Creates and returns an [iterator][] of `[index, byte]` pairs from the Buffer
 contents.
 
 ```js
-const buf = new Buffer('buffer');
+const buf = Buffer.from('buffer');
 for (var pair of buf.entries()) {
   console.log(pair);
 }
@@ -463,9 +741,9 @@ Returns a boolean indicating whether `this` and `otherBuffer` have exactly the
 same bytes.
 
 ```js
-const buf1 = new Buffer('ABC');
-const buf2 = new Buffer('414243', 'hex');
-const buf3 = new Buffer('ABCD');
+const buf1 = Buffer.from('ABC');
+const buf2 = Buffer.from('414243', 'hex');
+const buf3 = Buffer.from('ABCD');
 
 console.log(buf1.equals(buf2));
   // Prints: true
@@ -488,7 +766,7 @@ This is meant as a small simplification to creating a Buffer. Allowing the
 creation and fill of the Buffer to be done on a single line:
 
 ```js
-const b = new Buffer(50).fill('h');
+const b = Buffer.alloc(50, 'h');
 console.log(b.toString());
   // Prints: hhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhhh
 ```
@@ -501,7 +779,7 @@ falls in between a multi-byte character then whatever bytes fit into the buffer
 are written.
 
 ```js
-Buffer(3).fill('\u0222');
+Buffer.alloc(3, '\u0222');
   // Prints: <Buffer c8 a2 c8>
 ```
 
@@ -519,22 +797,22 @@ default interpreted as UTF8. Buffers will use the entire Buffer (to compare a
 partial Buffer use [`buf.slice()`][]).  Numbers can range from 0 to 255.
 
 ```js
-const buf = new Buffer('this is a buffer');
+const buf = Buffer.from('this is a buffer');
 
 buf.indexOf('this');
   // returns 0
 buf.indexOf('is');
   // returns 2
-buf.indexOf(new Buffer('a buffer'));
+buf.indexOf(Buffer.from('a buffer'));
   // returns 8
 buf.indexOf(97); // ascii for 'a'
   // returns 8
-buf.indexOf(new Buffer('a buffer example'));
+buf.indexOf(Buffer.from('a buffer example'));
   // returns -1
-buf.indexOf(new Buffer('a buffer example').slice(0,8));
+buf.indexOf(Buffer.from('a buffer example').slice(0,8));
   // returns 8
 
-const utf16Buffer = new Buffer('\u039a\u0391\u03a3\u03a3\u0395', 'ucs2');
+const utf16Buffer = Buffer.from('\u039a\u0391\u03a3\u03a3\u0395', 'ucs2');
 
 utf16Buffer.indexOf('\u03a3',  0, 'ucs2');
   // returns 4
@@ -557,19 +835,19 @@ Buffer use [`buf.slice()`][]). Numbers can range from 0 to 255.
 The `byteOffset` indicates the index in `buf` where searching begins.
 
 ```js
-const buf = new Buffer('this is a buffer');
+const buf = Buffer.from('this is a buffer');
 
 buf.includes('this');
   // returns true
 buf.includes('is');
   // returns true
-buf.includes(new Buffer('a buffer'));
+buf.includes(Buffer.from('a buffer'));
   // returns true
 buf.includes(97); // ascii for 'a'
   // returns true
-buf.includes(new Buffer('a buffer example'));
+buf.includes(Buffer.from('a buffer example'));
   // returns false
-buf.includes(new Buffer('a buffer example').slice(0,8));
+buf.includes(Buffer.from('a buffer example').slice(0,8));
   // returns true
 buf.includes('this', 4);
   // returns false
@@ -582,7 +860,7 @@ buf.includes('this', 4);
 Creates and returns an [iterator][] of Buffer keys (indices).
 
 ```js
-const buf = new Buffer('buffer');
+const buf = Buffer.from('buffer');
 for (var key of buf.keys()) {
   console.log(key);
 }
@@ -605,7 +883,7 @@ Buffer. For instance, in the example below, a Buffer with 1234 bytes is
 allocated, but only 11 ASCII bytes are written.
 
 ```js
-const buf = new Buffer(1234);
+const buf = Buffer.allocUnsafe(1234);
 
 console.log(buf.length);
   // Prints: 1234
@@ -621,7 +899,7 @@ modify the length of a Buffer should therefore treat `length` as read-only and
 use [`buf.slice()`][] to create a new Buffer.
 
 ```js
-var buf = new Buffer(10);
+var buf = Buffer.allocUnsafe(10);
 buf.write('abcdefghj', 0, 'ascii');
 console.log(buf.length);
   // Prints: 10
@@ -645,7 +923,7 @@ Setting `noAssert` to `true` skips validation of the `offset`. This allows the
 `offset` to be beyond the end of the Buffer.
 
 ```js
-const buf = new Buffer([1,2,3,4,5,6,7,8]);
+const buf = Buffer.from([1,2,3,4,5,6,7,8]);
 
 buf.readDoubleBE();
   // Returns: 8.20788039913184e-304
@@ -673,7 +951,7 @@ Setting `noAssert` to `true` skips validation of the `offset`. This allows the
 `offset` to be beyond the end of the Buffer.
 
 ```js
-const buf = new Buffer([1,2,3,4]);
+const buf = Buffer.from([1,2,3,4]);
 
 buf.readFloatBE();
   // Returns: 2.387939260590663e-38
@@ -700,7 +978,7 @@ Setting `noAssert` to `true` skips validation of the `offset`. This allows the
 Integers read from the Buffer are interpreted as two's complement signed values.
 
 ```js
-const buf = new Buffer([1,-2,3,4]);
+const buf = Buffer.from([1,-2,3,4]);
 
 buf.readInt8(0);
   // returns 1
@@ -725,7 +1003,7 @@ Setting `noAssert` to `true` skips validation of the `offset`. This allows the
 Integers read from the Buffer are interpreted as two's complement signed values.
 
 ```js
-const buf = new Buffer([1,-2,3,4]);
+const buf = Buffer.from([1,-2,3,4]);
 
 buf.readInt16BE();
   // returns 510
@@ -750,7 +1028,7 @@ Setting `noAssert` to `true` skips validation of the `offset`. This allows the
 Integers read from the Buffer are interpreted as two's complement signed values.
 
 ```js
-const buf = new Buffer([1,-2,3,4]);
+const buf = Buffer.from([1,-2,3,4]);
 
 buf.readInt32BE();
   // returns 33424132
@@ -771,7 +1049,7 @@ and interprets the result as a two's complement signed value. Supports up to 48
 bits of accuracy. For example:
 
 ```js
-const buf = new Buffer(6);
+const buf = Buffer.allocUnsafe(6);
 buf.writeUInt16LE(0x90ab, 0);
 buf.writeUInt32LE(0x12345678, 2);
 buf.readIntLE(0, 6).toString(16);  // Specify 6 bytes (48 bits)
@@ -796,7 +1074,7 @@ Setting `noAssert` to `true` skips validation of the `offset`. This allows the
 `offset` to be beyond the end of the Buffer.
 
 ```js
-const buf = new Buffer([1,-2,3,4]);
+const buf = Buffer.from([1,-2,3,4]);
 
 buf.readUInt8(0);
   // returns 1
@@ -821,7 +1099,7 @@ Setting `noAssert` to `true` skips validation of the `offset`. This allows the
 Example:
 
 ```js
-const buf = new Buffer([0x3, 0x4, 0x23, 0x42]);
+const buf = Buffer.from([0x3, 0x4, 0x23, 0x42]);
 
 buf.readUInt16BE(0);
   // Returns: 0x0304
@@ -854,7 +1132,7 @@ Setting `noAssert` to `true` skips validation of the `offset`. This allows the
 Example:
 
 ```js
-const buf = new Buffer([0x3, 0x4, 0x23, 0x42]);
+const buf = Buffer.from([0x3, 0x4, 0x23, 0x42]);
 
 buf.readUInt32BE(0);
   // Returns: 0x03042342
@@ -875,7 +1153,7 @@ and interprets the result as an unsigned integer. Supports up to 48
 bits of accuracy. For example:
 
 ```js
-const buf = new Buffer(6);
+const buf = Buffer.allocUnsafe(6);
 buf.writeUInt16LE(0x90ab, 0);
 buf.writeUInt32LE(0x12345678, 2);
 buf.readUIntLE(0, 6).toString(16);  // Specify 6 bytes (48 bits)
@@ -904,7 +1182,7 @@ Example: build a Buffer with the ASCII alphabet, take a slice, then modify one
 byte from the original Buffer.
 
 ```js
-const buf1 = new Buffer(26);
+const buf1 = Buffer.allocUnsafe(26);
 
 for (var i = 0 ; i < 26 ; i++) {
   buf1[i] = i + 97; // 97 is ASCII a
@@ -922,7 +1200,7 @@ Specifying negative indexes causes the slice to be generated relative to the
 end of the Buffer rather than the beginning.
 
 ```js
-const buf = new Buffer('buffer');
+const buf = Buffer.from('buffer');
 
 buf.slice(-6, -1).toString();
   // Returns 'buffe', equivalent to buf.slice(0, 5)
@@ -943,7 +1221,7 @@ Decodes and returns a string from the Buffer data using the specified
 character set `encoding`.
 
 ```js
-const buf = new Buffer(26);
+const buf = Buffer.allocUnsafe(26);
 for (var i = 0 ; i < 26 ; i++) {
   buf[i] = i + 97; // 97 is ASCII a
 }
@@ -967,7 +1245,7 @@ implicitly calls this function when stringifying a Buffer instance.
 Example:
 
 ```js
-const buf = new Buffer('test');
+const buf = Buffer.from('test');
 const json = JSON.stringify(buf);
 
 console.log(json);
@@ -975,7 +1253,7 @@ console.log(json);
 
 const copy = JSON.parse(json, (key, value) => {
     return value && value.type === 'Buffer'
-      ? new Buffer(value.data)
+      ? Buffer.from(value.data)
       : value;
   });
 
@@ -991,7 +1269,7 @@ Creates and returns an [iterator][] for Buffer values (bytes). This function is
 called automatically when the Buffer is used in a `for..of` statement.
 
 ```js
-const buf = new Buffer('buffer');
+const buf = Buffer.from('buffer');
 for (var value of buf.values()) {
   console.log(value);
 }
@@ -1030,7 +1308,7 @@ string will be written however, it will not write only partially encoded
 characters.
 
 ```js
-const buf = new Buffer(256);
+const buf = Buffer.allocUnsafe(256);
 const len = buf.write('\u00bd + \u00bc = \u00be', 0);
 console.log(`${len} bytes: ${buf.toString('utf8', 0, len)}`);
   // Prints: 12 bytes: ½ + ¼ = ¾
@@ -1056,7 +1334,7 @@ should not be used unless you are certain of correctness.
 Example:
 
 ```js
-const buf = new Buffer(8);
+const buf = Buffer.allocUnsafe(8);
 buf.writeDoubleBE(0xdeadbeefcafebabe, 0);
 
 console.log(buf);
@@ -1089,7 +1367,7 @@ should not be used unless you are certain of correctness.
 Example:
 
 ```js
-const buf = new Buffer(4);
+const buf = Buffer.allocUnsafe(4);
 buf.writeFloatBE(0xcafebabe, 0);
 
 console.log(buf);
@@ -1119,7 +1397,7 @@ should not be used unless you are certain of correctness.
 The `value` is interpreted and written as a two's complement signed integer.
 
 ```js
-const buf = new Buffer(2);
+const buf = Buffer.allocUnsafe(2);
 buf.writeInt8(2, 0);
 buf.writeInt8(-2, 1);
 console.log(buf);
@@ -1146,7 +1424,7 @@ should not be used unless you are certain of correctness.
 The `value` is interpreted and written as a two's complement signed integer.
 
 ```js
-const buf = new Buffer(4);
+const buf = Buffer.allocUnsafe(4);
 buf.writeInt16BE(0x0102,0);
 buf.writeInt16LE(0x0304,2);
 console.log(buf);
@@ -1173,7 +1451,7 @@ should not be used unless you are certain of correctness.
 The `value` is interpreted and written as a two's complement signed integer.
 
 ```js
-const buf = new Buffer(8);
+const buf = Buffer.allocUnsafe(8);
 buf.writeInt32BE(0x01020304,0);
 buf.writeInt32LE(0x05060708,4);
 console.log(buf);
@@ -1193,12 +1471,12 @@ Writes `value` to the Buffer at the specified `offset` and `byteLength`.
 Supports up to 48 bits of accuracy. For example:
 
 ```js
-const buf1 = new Buffer(6);
+const buf1 = Buffer.allocUnsafe(6);
 buf1.writeUIntBE(0x1234567890ab, 0, 6);
 console.log(buf1);
   // Prints: <Buffer 12 34 56 78 90 ab>
 
-const buf2 = new Buffer(6);
+const buf2 = Buffer.allocUnsafe(6);
 buf2.writeUIntLE(0x1234567890ab, 0, 6);
 console.log(buf2);
   // Prints: <Buffer ab 90 78 56 34 12>
@@ -1227,7 +1505,7 @@ should not be used unless you are certain of correctness.
 Example:
 
 ```js
-const buf = new Buffer(4);
+const buf = Buffer.allocUnsafe(4);
 buf.writeUInt8(0x3, 0);
 buf.writeUInt8(0x4, 1);
 buf.writeUInt8(0x23, 2);
@@ -1257,7 +1535,7 @@ should not be used unless you are certain of correctness.
 Example:
 
 ```js
-const buf = new Buffer(4);
+const buf = Buffer.allocUnsafe(4);
 buf.writeUInt16BE(0xdead, 0);
 buf.writeUInt16BE(0xbeef, 2);
 
@@ -1291,7 +1569,7 @@ should not be used unless you are certain of correctness.
 Example:
 
 ```js
-const buf = new Buffer(4);
+const buf = Buffer.allocUnsafe(4);
 buf.writeUInt32BE(0xfeedface, 0);
 
 console.log(buf);
@@ -1316,7 +1594,7 @@ Writes `value` to the Buffer at the specified `offset` and `byteLength`.
 Supports up to 48 bits of accuracy. For example:
 
 ```js
-const buf = new Buffer(6);
+const buf = Buffer.allocUnsafe(6);
 buf.writeUIntBE(0x1234567890ab, 0, 6);
 console.log(buf);
   // Prints: <Buffer 12 34 56 78 90 ab>
@@ -1358,7 +1636,7 @@ const store = [];
 socket.on('readable', () => {
   var data = socket.read();
   // allocate for retained data
-  var sb = new SlowBuffer(10);
+  var sb = SlowBuffer(10);
   // copy the data into the new allocation
   data.copy(sb, 0, 0, 10);
   store.push(sb);
@@ -1368,6 +1646,31 @@ socket.on('readable', () => {
 Use of `SlowBuffer` should be used only as a last resort *after* a developer
 has observed undue memory retention in their applications.
 
+### new SlowBuffer(size)
+
+* `size` Number
+
+Allocates a new `SlowBuffer` of `size` bytes.  The `size` must be less than
+or equal to the value of `require('buffer').kMaxLength` (on 64-bit
+architectures, `kMaxLength` is `(2^31)-1`). Otherwise, a [`RangeError`][] is
+thrown. If a `size` less than 0 is specified, a zero-length `SlowBuffer` will be
+created.
+
+The underlying memory for `SlowBuffer` instances is *not initialized*. The
+contents of a newly created `SlowBuffer` are unknown and could contain
+sensitive data. Use [`buf.fill(0)`][] to initialize a `SlowBuffer` to zeroes.
+
+```js
+const SlowBuffer = require('buffer').SlowBuffer;
+const buf = new SlowBuffer(5);
+console.log(buf);
+  // <Buffer 78 e0 82 02 01>
+  // (octets will be different, every time)
+buf.fill(0);
+console.log(buf);
+  // <Buffer 00 00 00 00 00>
+```
+
 [`Array#includes()`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/includes
 [`Array#indexOf()`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/indexOf
 [`buf.entries()`]: #buffer_buf_entries
@@ -1382,3 +1685,10 @@ has observed undue memory retention in their applications.
 [`util.inspect()`]: util.html#util_util_inspect_object_options
 [iterator]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Iteration_protocols
 [RFC 4648, Section 5]: https://tools.ietf.org/html/rfc4648#section-5
+[buffer_from_array]: #buffer_class_method_buffer_from_array
+[buffer_from_buffer]: #buffer_class_method_buffer_from_buffer
+[buffer_from_arraybuf]: #buffer_class_method_buffer_from_arraybuffer
+[buffer_from_string]: #buffer_class_method_buffer_from_str_encoding
+[buffer_allocunsafe]: #buffer_class_method_buffer_allocraw_size
+[buffer_alloc]: #buffer_class_method_buffer_alloc_size_fill_encoding
+[`TypedArray.from()`]: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/TypedArray/from
\ No newline at end of file
diff --git a/lib/buffer.js b/lib/buffer.js
index f126aee5a3e8cf..58e5e47d9d0c18 100644
--- a/lib/buffer.js
+++ b/lib/buffer.js
@@ -10,6 +10,7 @@ exports.SlowBuffer = SlowBuffer;
 exports.INSPECT_MAX_BYTES = 50;
 exports.kMaxLength = binding.kMaxLength;
 
+const kFromErrorMsg = 'must start with number, buffer, array or string';
 
 Buffer.poolSize = 8 * 1024;
 var poolSize, poolOffset, allocPool;
@@ -44,27 +45,77 @@ function alignPool() {
 }
 
 
-function Buffer(arg, encoding) {
+function Buffer(arg, encodingOrOffset, length) {
   // Common case.
   if (typeof arg === 'number') {
-    // If less than zero, or NaN.
-    if (arg < 0 || arg !== arg)
-      arg = 0;
-    return allocate(arg);
-  }
-
-  // Slightly less common case.
-  if (typeof arg === 'string') {
-    return fromString(arg, encoding);
+    if (typeof encodingOrOffset === 'string') {
+      throw new Error(
+        'If encoding is specified then the first argument must be a string'
+      );
+    }
+    return Buffer.allocUnsafe(arg);
   }
-
-  // Unusual.
-  return fromObject(arg);
+  return Buffer.from(arg, encodingOrOffset, length);
 }
 
+/**
+ * Functionally equivalent to Buffer(arg, encoding) but throws a TypeError
+ * if value is a number.
+ * Buffer.from(str[, encoding])
+ * Buffer.from(array)
+ * Buffer.from(buffer)
+ * Buffer.from(arrayBuffer[, byteOffset[, length]])
+ **/
+Buffer.from = function(value, encodingOrOffset, length) {
+  if (typeof value === 'number')
+    throw new TypeError('"value" argument must not be a number');
+
+  if (value instanceof ArrayBuffer)
+    return fromArrayBuffer(value, encodingOrOffset, length);
+
+  if (typeof value === 'string')
+    return fromString(value, encodingOrOffset);
+
+  return fromObject(value);
+};
+
 Object.setPrototypeOf(Buffer.prototype, Uint8Array.prototype);
 Object.setPrototypeOf(Buffer, Uint8Array);
 
+/**
+ * Creates a new filled Buffer instance.
+ * alloc(size[, fill[, encoding]])
+ **/
+Buffer.alloc = function(size, fill, encoding) {
+  if (typeof size !== 'number')
+    throw new TypeError('"size" argument must be a number');
+  if (size <= 0)
+    return createBuffer(size);
+  if (fill !== undefined) {
+    // Since we are filling anyway, don't zero fill initially.
+    flags[kNoZeroFill] = 1;
+    // Only pay attention to encoding if it's a string. This
+    // prevents accidentally sending in a number that would
+    // be interpretted as a start offset.
+    return typeof encoding === 'string' ?
+        createBuffer(size).fill(fill, encoding) :
+        createBuffer(size).fill(fill);
+  }
+  flags[kNoZeroFill] = 0;
+  return createBuffer(size);
+};
+
+/**
+ * Equivalent to Buffer(num), by default creates a non-zero-filled Buffer
+ * instance. If `--zero-fill-buffers` is set, will zero-fill the buffer.
+ **/
+Buffer.allocUnsafe = function(size) {
+  if (typeof size !== 'number')
+    throw new TypeError('"size" argument must be a number');
+  if (size > 0)
+    flags[kNoZeroFill] = 1;
+  return allocate(size);
+};
 
 function SlowBuffer(length) {
   if (+length != length)
@@ -104,6 +155,9 @@ function fromString(string, encoding) {
   if (typeof encoding !== 'string' || encoding === '')
     encoding = 'utf8';
 
+  if (!Buffer.isEncoding(encoding))
+    throw new TypeError('"encoding" must be a valid string encoding');
+
   var length = byteLength(string, encoding);
   if (length >= (Buffer.poolSize >>> 1))
     return binding.createFromString(string, encoding);
@@ -125,6 +179,16 @@ function fromArrayLike(obj) {
   return b;
 }
 
+function fromArrayBuffer(obj, byteOffset, length) {
+  byteOffset >>>= 0;
+
+  if (typeof length === 'undefined')
+    return binding.createFromArrayBuffer(obj, byteOffset);
+
+  length >>>= 0;
+  return binding.createFromArrayBuffer(obj, byteOffset, length);
+}
+
 function fromObject(obj) {
   if (obj instanceof Buffer) {
     const b = allocate(obj.length);
@@ -136,26 +200,20 @@ function fromObject(obj) {
     return b;
   }
 
-  if (obj == null) {
-    throw new TypeError('must start with number, buffer, array or string');
-  }
-
-  if (obj instanceof ArrayBuffer) {
-    return binding.createFromArrayBuffer(obj);
-  }
-
-  if (obj.buffer instanceof ArrayBuffer || 'length' in obj) {
-    if (typeof obj.length !== 'number' || obj.length !== obj.length) {
-      return allocate(0);
+  if (obj) {
+    if (obj.buffer instanceof ArrayBuffer || 'length' in obj) {
+      if (typeof obj.length !== 'number' || obj.length !== obj.length) {
+        return allocate(0);
+      }
+      return fromArrayLike(obj);
     }
-    return fromArrayLike(obj);
-  }
 
-  if (obj.type === 'Buffer' && Array.isArray(obj.data)) {
-    return fromArrayLike(obj.data);
+    if (obj.type === 'Buffer' && Array.isArray(obj.data)) {
+      return fromArrayLike(obj.data);
+    }
   }
 
-  throw new TypeError('must start with number, buffer, array or string');
+  throw new TypeError(kFromErrorMsg);
 }
 
 
@@ -211,7 +269,7 @@ Buffer.concat = function(list, length) {
     throw new TypeError('list argument must be an Array of Buffers');
 
   if (list.length === 0)
-    return new Buffer(0);
+    return Buffer.alloc(0);
 
   if (length === undefined) {
     length = 0;
@@ -221,7 +279,7 @@ Buffer.concat = function(list, length) {
     length = length >>> 0;
   }
 
-  var buffer = new Buffer(length);
+  var buffer = Buffer.allocUnsafe(length);
   var pos = 0;
   for (let i = 0; i < list.length; i++) {
     var buf = list[i];
@@ -450,7 +508,7 @@ function slowIndexOf(buffer, val, byteOffset, encoding) {
       case 'ascii':
       case 'hex':
         return binding.indexOfBuffer(
-            buffer, Buffer(val, encoding), byteOffset, encoding);
+            buffer, Buffer.from(val, encoding), byteOffset, encoding);
 
       default:
         if (loweredCase) {
@@ -514,6 +572,11 @@ Buffer.prototype.fill = function fill(val, start, end, encoding) {
       if (code < 256)
         val = code;
     }
+    if (val.length === 0) {
+      // Previously, if val === '', the Buffer would not fill,
+      // which is rather surprising.
+      val = 0;
+    }
     if (encoding !== undefined && typeof encoding !== 'string') {
       throw new TypeError('encoding must be a string');
     }
diff --git a/src/node_buffer.cc b/src/node_buffer.cc
index 1c60a311a531e8..99ae5abee216d8 100644
--- a/src/node_buffer.cc
+++ b/src/node_buffer.cc
@@ -429,7 +429,20 @@ void CreateFromArrayBuffer(const FunctionCallbackInfo<Value>& args) {
   if (!args[0]->IsArrayBuffer())
     return env->ThrowTypeError("argument is not an ArrayBuffer");
   Local<ArrayBuffer> ab = args[0].As<ArrayBuffer>();
-  Local<Uint8Array> ui = Uint8Array::New(ab, 0, ab->ByteLength());
+
+  size_t ab_length = ab->ByteLength();
+  size_t offset;
+  size_t max_length;
+
+  CHECK_NOT_OOB(ParseArrayIndex(args[1], 0, &offset));
+  CHECK_NOT_OOB(ParseArrayIndex(args[2], ab_length - offset, &max_length));
+
+  if (offset >= ab_length)
+    return env->ThrowRangeError("'offset' is out of bounds");
+  if (max_length > ab_length - offset)
+    return env->ThrowRangeError("'length' is out of bounds");
+
+  Local<Uint8Array> ui = Uint8Array::New(ab, offset, max_length);
   Maybe<bool> mb =
       ui->SetPrototype(env->context(), env->buffer_prototype_object());
   if (!mb.FromMaybe(false))
diff --git a/test/parallel/test-buffer-alloc.js b/test/parallel/test-buffer-alloc.js
new file mode 100644
index 00000000000000..8b9dae91647231
--- /dev/null
+++ b/test/parallel/test-buffer-alloc.js
@@ -0,0 +1,1431 @@
+'use strict';
+var common = require('../common');
+var assert = require('assert');
+
+var Buffer = require('buffer').Buffer;
+var SlowBuffer = require('buffer').SlowBuffer;
+
+// counter to ensure unique value is always copied
+var cntr = 0;
+
+var b = Buffer.alloc(1024);
+
+console.log('b.length == %d', b.length);
+assert.strictEqual(1024, b.length);
+
+b[0] = -1;
+assert.strictEqual(b[0], 255);
+
+for (let i = 0; i < 1024; i++) {
+  b[i] = i % 256;
+}
+
+for (let i = 0; i < 1024; i++) {
+  assert.strictEqual(i % 256, b[i]);
+}
+
+var c = Buffer.alloc(512);
+console.log('c.length == %d', c.length);
+assert.strictEqual(512, c.length);
+
+var d = Buffer.from([]);
+assert.strictEqual(0, d.length);
+
+var ui32 = new Uint32Array(4).fill(42);
+var e = Buffer.from(ui32);
+assert.deepEqual(ui32, e);
+
+// First check Buffer#fill() works as expected.
+
+assert.throws(function() {
+  Buffer.allocUnsafe(8).fill('a', -1);
+});
+
+assert.throws(function() {
+  Buffer.allocUnsafe(8).fill('a', 0, 9);
+});
+
+// Make sure this doesn't hang indefinitely.
+Buffer.allocUnsafe(8).fill('');
+
+{
+  const buf = Buffer.allocUnsafe(64);
+  buf.fill(10);
+  for (let i = 0; i < buf.length; i++)
+    assert.equal(buf[i], 10);
+
+  buf.fill(11, 0, buf.length >> 1);
+  for (let i = 0; i < buf.length >> 1; i++)
+    assert.equal(buf[i], 11);
+  for (let i = (buf.length >> 1) + 1; i < buf.length; i++)
+    assert.equal(buf[i], 10);
+
+  buf.fill('h');
+  for (let i = 0; i < buf.length; i++)
+    assert.equal('h'.charCodeAt(0), buf[i]);
+
+  buf.fill(0);
+  for (let i = 0; i < buf.length; i++)
+    assert.equal(0, buf[i]);
+
+  buf.fill(null);
+  for (let i = 0; i < buf.length; i++)
+    assert.equal(0, buf[i]);
+
+  buf.fill(1, 16, 32);
+  for (let i = 0; i < 16; i++)
+    assert.equal(0, buf[i]);
+  for (let i = 16; i < 32; i++)
+    assert.equal(1, buf[i]);
+  for (let i = 32; i < buf.length; i++)
+    assert.equal(0, buf[i]);
+}
+
+{
+  const buf = Buffer.allocUnsafe(10);
+  buf.fill('abc');
+  assert.equal(buf.toString(), 'abcabcabca');
+  buf.fill('է');
+  assert.equal(buf.toString(), 'էէէէէ');
+}
+
+{
+  // copy 512 bytes, from 0 to 512.
+  b.fill(++cntr);
+  c.fill(++cntr);
+  const copied = b.copy(c, 0, 0, 512);
+  console.log('copied %d bytes from b into c', copied);
+  assert.strictEqual(512, copied);
+  for (let i = 0; i < c.length; i++) {
+    assert.strictEqual(b[i], c[i]);
+  }
+}
+
+{
+  // copy c into b, without specifying sourceEnd
+  b.fill(++cntr);
+  c.fill(++cntr);
+  const copied = c.copy(b, 0, 0);
+  console.log('copied %d bytes from c into b w/o sourceEnd', copied);
+  assert.strictEqual(c.length, copied);
+  for (let i = 0; i < c.length; i++) {
+    assert.strictEqual(c[i], b[i]);
+  }
+}
+
+{
+  // copy c into b, without specifying sourceStart
+  b.fill(++cntr);
+  c.fill(++cntr);
+  const copied = c.copy(b, 0);
+  console.log('copied %d bytes from c into b w/o sourceStart', copied);
+  assert.strictEqual(c.length, copied);
+  for (let i = 0; i < c.length; i++) {
+    assert.strictEqual(c[i], b[i]);
+  }
+}
+
+{
+  // copy longer buffer b to shorter c without targetStart
+  b.fill(++cntr);
+  c.fill(++cntr);
+  const copied = b.copy(c);
+  console.log('copied %d bytes from b into c w/o targetStart', copied);
+  assert.strictEqual(c.length, copied);
+  for (let i = 0; i < c.length; i++) {
+    assert.strictEqual(b[i], c[i]);
+  }
+}
+
+{
+  // copy starting near end of b to c
+  b.fill(++cntr);
+  c.fill(++cntr);
+  const copied = b.copy(c, 0, b.length - Math.floor(c.length / 2));
+  console.log('copied %d bytes from end of b into beginning of c', copied);
+  assert.strictEqual(Math.floor(c.length / 2), copied);
+  for (let i = 0; i < Math.floor(c.length / 2); i++) {
+    assert.strictEqual(b[b.length - Math.floor(c.length / 2) + i], c[i]);
+  }
+  for (let i = Math.floor(c.length / 2) + 1; i < c.length; i++) {
+    assert.strictEqual(c[c.length - 1], c[i]);
+  }
+}
+
+{
+  // try to copy 513 bytes, and check we don't overrun c
+  b.fill(++cntr);
+  c.fill(++cntr);
+  const copied = b.copy(c, 0, 0, 513);
+  console.log('copied %d bytes from b trying to overrun c', copied);
+  assert.strictEqual(c.length, copied);
+  for (let i = 0; i < c.length; i++) {
+    assert.strictEqual(b[i], c[i]);
+  }
+}
+
+{
+  // copy 768 bytes from b into b
+  b.fill(++cntr);
+  b.fill(++cntr, 256);
+  const copied = b.copy(b, 0, 256, 1024);
+  console.log('copied %d bytes from b into b', copied);
+  assert.strictEqual(768, copied);
+  for (let i = 0; i < b.length; i++) {
+    assert.strictEqual(cntr, b[i]);
+  }
+}
+
+// copy string longer than buffer length (failure will segfault)
+var bb = Buffer.allocUnsafe(10);
+bb.fill('hello crazy world');
+
+
+// try to copy from before the beginning of b
+assert.doesNotThrow(() => { b.copy(c, 0, 100, 10); });
+
+// copy throws at negative sourceStart
+assert.throws(function() {
+  Buffer.allocUnsafe(5).copy(Buffer.allocUnsafe(5), 0, -1);
+}, RangeError);
+
+{
+  // check sourceEnd resets to targetEnd if former is greater than the latter
+  b.fill(++cntr);
+  c.fill(++cntr);
+  const copied = b.copy(c, 0, 0, 1025);
+  console.log('copied %d bytes from b into c', copied);
+  for (let i = 0; i < c.length; i++) {
+    assert.strictEqual(b[i], c[i]);
+  }
+}
+
+// throw with negative sourceEnd
+console.log('test copy at negative sourceEnd');
+assert.throws(function() {
+  b.copy(c, 0, 0, -1);
+}, RangeError);
+
+// when sourceStart is greater than sourceEnd, zero copied
+assert.equal(b.copy(c, 0, 100, 10), 0);
+
+// when targetStart > targetLength, zero copied
+assert.equal(b.copy(c, 512, 0, 10), 0);
+
+var caught_error;
+
+// invalid encoding for Buffer.toString
+caught_error = null;
+try {
+  b.toString('invalid');
+} catch (err) {
+  caught_error = err;
+}
+assert.strictEqual('Unknown encoding: invalid', caught_error.message);
+
+// invalid encoding for Buffer.write
+caught_error = null;
+try {
+  b.write('test string', 0, 5, 'invalid');
+} catch (err) {
+  caught_error = err;
+}
+assert.strictEqual('Unknown encoding: invalid', caught_error.message);
+
+// try to create 0-length buffers
+Buffer.from('');
+Buffer.from('', 'ascii');
+Buffer.from('', 'binary');
+Buffer.alloc(0);
+
+// try to write a 0-length string beyond the end of b
+assert.throws(function() {
+  b.write('', 2048);
+}, RangeError);
+
+// throw when writing to negative offset
+assert.throws(function() {
+  b.write('a', -1);
+}, RangeError);
+
+// throw when writing past bounds from the pool
+assert.throws(function() {
+  b.write('a', 2048);
+}, RangeError);
+
+// throw when writing to negative offset
+assert.throws(function() {
+  b.write('a', -1);
+}, RangeError);
+
+// try to copy 0 bytes worth of data into an empty buffer
+b.copy(Buffer.alloc(0), 0, 0, 0);
+
+// try to copy 0 bytes past the end of the target buffer
+b.copy(Buffer.alloc(0), 1, 1, 1);
+b.copy(Buffer.allocUnsafe(1), 1, 1, 1);
+
+// try to copy 0 bytes from past the end of the source buffer
+b.copy(Buffer.allocUnsafe(1), 0, 2048, 2048);
+
+const rangeBuffer = Buffer.from('abc');
+
+// if start >= buffer's length, empty string will be returned
+assert.equal(rangeBuffer.toString('ascii', 3), '');
+assert.equal(rangeBuffer.toString('ascii', +Infinity), '');
+assert.equal(rangeBuffer.toString('ascii', 3.14, 3), '');
+assert.equal(rangeBuffer.toString('ascii', 'Infinity', 3), '');
+
+// if end <= 0, empty string will be returned
+assert.equal(rangeBuffer.toString('ascii', 1, 0), '');
+assert.equal(rangeBuffer.toString('ascii', 1, -1.2), '');
+assert.equal(rangeBuffer.toString('ascii', 1, -100), '');
+assert.equal(rangeBuffer.toString('ascii', 1, -Infinity), '');
+
+// if start < 0, start will be taken as zero
+assert.equal(rangeBuffer.toString('ascii', -1, 3), 'abc');
+assert.equal(rangeBuffer.toString('ascii', -1.99, 3), 'abc');
+assert.equal(rangeBuffer.toString('ascii', -Infinity, 3), 'abc');
+assert.equal(rangeBuffer.toString('ascii', '-1', 3), 'abc');
+assert.equal(rangeBuffer.toString('ascii', '-1.99', 3), 'abc');
+assert.equal(rangeBuffer.toString('ascii', '-Infinity', 3), 'abc');
+
+// if start is an invalid integer, start will be taken as zero
+assert.equal(rangeBuffer.toString('ascii', 'node.js', 3), 'abc');
+assert.equal(rangeBuffer.toString('ascii', {}, 3), 'abc');
+assert.equal(rangeBuffer.toString('ascii', [], 3), 'abc');
+assert.equal(rangeBuffer.toString('ascii', NaN, 3), 'abc');
+assert.equal(rangeBuffer.toString('ascii', null, 3), 'abc');
+assert.equal(rangeBuffer.toString('ascii', undefined, 3), 'abc');
+assert.equal(rangeBuffer.toString('ascii', false, 3), 'abc');
+assert.equal(rangeBuffer.toString('ascii', '', 3), 'abc');
+
+// but, if start is an integer when coerced, then it will be coerced and used.
+assert.equal(rangeBuffer.toString('ascii', '-1', 3), 'abc');
+assert.equal(rangeBuffer.toString('ascii', '1', 3), 'bc');
+assert.equal(rangeBuffer.toString('ascii', '-Infinity', 3), 'abc');
+assert.equal(rangeBuffer.toString('ascii', '3', 3), '');
+assert.equal(rangeBuffer.toString('ascii', Number(3), 3), '');
+assert.equal(rangeBuffer.toString('ascii', '3.14', 3), '');
+assert.equal(rangeBuffer.toString('ascii', '1.99', 3), 'bc');
+assert.equal(rangeBuffer.toString('ascii', '-1.99', 3), 'abc');
+assert.equal(rangeBuffer.toString('ascii', 1.99, 3), 'bc');
+assert.equal(rangeBuffer.toString('ascii', true, 3), 'bc');
+
+// if end > buffer's length, end will be taken as buffer's length
+assert.equal(rangeBuffer.toString('ascii', 0, 5), 'abc');
+assert.equal(rangeBuffer.toString('ascii', 0, 6.99), 'abc');
+assert.equal(rangeBuffer.toString('ascii', 0, Infinity), 'abc');
+assert.equal(rangeBuffer.toString('ascii', 0, '5'), 'abc');
+assert.equal(rangeBuffer.toString('ascii', 0, '6.99'), 'abc');
+assert.equal(rangeBuffer.toString('ascii', 0, 'Infinity'), 'abc');
+
+// if end is an invalid integer, end will be taken as buffer's length
+assert.equal(rangeBuffer.toString('ascii', 0, 'node.js'), '');
+assert.equal(rangeBuffer.toString('ascii', 0, {}), '');
+assert.equal(rangeBuffer.toString('ascii', 0, NaN), '');
+assert.equal(rangeBuffer.toString('ascii', 0, undefined), 'abc');
+assert.equal(rangeBuffer.toString('ascii', 0), 'abc');
+assert.equal(rangeBuffer.toString('ascii', 0, null), '');
+assert.equal(rangeBuffer.toString('ascii', 0, []), '');
+assert.equal(rangeBuffer.toString('ascii', 0, false), '');
+assert.equal(rangeBuffer.toString('ascii', 0, ''), '');
+
+// but, if end is an integer when coerced, then it will be coerced and used.
+assert.equal(rangeBuffer.toString('ascii', 0, '-1'), '');
+assert.equal(rangeBuffer.toString('ascii', 0, '1'), 'a');
+assert.equal(rangeBuffer.toString('ascii', 0, '-Infinity'), '');
+assert.equal(rangeBuffer.toString('ascii', 0, '3'), 'abc');
+assert.equal(rangeBuffer.toString('ascii', 0, Number(3)), 'abc');
+assert.equal(rangeBuffer.toString('ascii', 0, '3.14'), 'abc');
+assert.equal(rangeBuffer.toString('ascii', 0, '1.99'), 'a');
+assert.equal(rangeBuffer.toString('ascii', 0, '-1.99'), '');
+assert.equal(rangeBuffer.toString('ascii', 0, 1.99), 'a');
+assert.equal(rangeBuffer.toString('ascii', 0, true), 'a');
+
+// try toString() with a object as a encoding
+assert.equal(rangeBuffer.toString({toString: function() {
+  return 'ascii';
+}}), 'abc');
+
+// testing for smart defaults and ability to pass string values as offset
+var writeTest = Buffer.from('abcdes');
+writeTest.write('n', 'ascii');
+writeTest.write('o', 'ascii', '1');
+writeTest.write('d', '2', 'ascii');
+writeTest.write('e', 3, 'ascii');
+writeTest.write('j', 'ascii', 4);
+assert.equal(writeTest.toString(), 'nodejs');
+
+// ASCII slice test
+{
+  const asciiString = 'hello world';
+
+  for (let i = 0; i < asciiString.length; i++) {
+    b[i] = asciiString.charCodeAt(i);
+  }
+  const asciiSlice = b.toString('ascii', 0, asciiString.length);
+  assert.equal(asciiString, asciiSlice);
+}
+
+{
+  const asciiString = 'hello world';
+  const offset = 100;
+
+  const written = b.write(asciiString, offset, 'ascii');
+  assert.equal(asciiString.length, written);
+  const asciiSlice = b.toString('ascii', offset, offset + asciiString.length);
+  assert.equal(asciiString, asciiSlice);
+}
+
+{
+  const asciiString = 'hello world';
+  const offset = 100;
+
+  const sliceA = b.slice(offset, offset + asciiString.length);
+  const sliceB = b.slice(offset, offset + asciiString.length);
+  for (let i = 0; i < asciiString.length; i++) {
+    assert.equal(sliceA[i], sliceB[i]);
+  }
+}
+
+// UTF-8 slice test
+
+var utf8String = '¡hέlló wôrld!';
+var offset = 100;
+
+b.write(utf8String, 0, Buffer.byteLength(utf8String), 'utf8');
+var utf8Slice = b.toString('utf8', 0, Buffer.byteLength(utf8String));
+assert.equal(utf8String, utf8Slice);
+
+var written = b.write(utf8String, offset, 'utf8');
+assert.equal(Buffer.byteLength(utf8String), written);
+utf8Slice = b.toString('utf8', offset, offset + Buffer.byteLength(utf8String));
+assert.equal(utf8String, utf8Slice);
+
+var sliceA = b.slice(offset, offset + Buffer.byteLength(utf8String));
+var sliceB = b.slice(offset, offset + Buffer.byteLength(utf8String));
+for (let i = 0; i < Buffer.byteLength(utf8String); i++) {
+  assert.equal(sliceA[i], sliceB[i]);
+}
+
+{
+  const slice = b.slice(100, 150);
+  assert.equal(50, slice.length);
+  for (let i = 0; i < 50; i++) {
+    assert.equal(b[100 + i], slice[i]);
+  }
+}
+
+{
+  // make sure only top level parent propagates from allocPool
+  const b = Buffer.allocUnsafe(5);
+  const c = b.slice(0, 4);
+  const d = c.slice(0, 2);
+  assert.equal(b.parent, c.parent);
+  assert.equal(b.parent, d.parent);
+}
+
+{
+  // also from a non-pooled instance
+  const b = new SlowBuffer(5);
+  const c = b.slice(0, 4);
+  const d = c.slice(0, 2);
+  assert.equal(c.parent, d.parent);
+}
+
+{
+  // Bug regression test
+  const testValue = '\u00F6\u65E5\u672C\u8A9E'; // ö日本語
+  const buffer = Buffer.allocUnsafe(32);
+  const size = buffer.write(testValue, 0, 'utf8');
+  console.log('bytes written to buffer: ' + size);
+  const slice = buffer.toString('utf8', 0, size);
+  assert.equal(slice, testValue);
+}
+
+{
+  // Test triple  slice
+  const a = Buffer.allocUnsafe(8);
+  for (let i = 0; i < 8; i++) a[i] = i;
+  const b = a.slice(4, 8);
+  assert.equal(4, b[0]);
+  assert.equal(5, b[1]);
+  assert.equal(6, b[2]);
+  assert.equal(7, b[3]);
+  const c = b.slice(2, 4);
+  assert.equal(6, c[0]);
+  assert.equal(7, c[1]);
+}
+
+{
+  const d = Buffer.from([23, 42, 255]);
+  assert.equal(d.length, 3);
+  assert.equal(d[0], 23);
+  assert.equal(d[1], 42);
+  assert.equal(d[2], 255);
+  assert.deepEqual(d, Buffer.from(d));
+}
+
+{
+  const e = Buffer.from('über');
+  console.error('uber: \'%s\'', e.toString());
+  assert.deepEqual(e, Buffer.from([195, 188, 98, 101, 114]));
+}
+
+{
+  const f = Buffer.from('über', 'ascii');
+  console.error('f.length: %d     (should be 4)', f.length);
+  assert.deepEqual(f, Buffer.from([252, 98, 101, 114]));
+}
+
+['ucs2', 'ucs-2', 'utf16le', 'utf-16le'].forEach(function(encoding) {
+  {
+    const f = Buffer.from('über', encoding);
+    console.error('f.length: %d     (should be 8)', f.length);
+    assert.deepEqual(f, Buffer.from([252, 0, 98, 0, 101, 0, 114, 0]));
+  }
+
+  {
+    const f = Buffer.from('привет', encoding);
+    console.error('f.length: %d     (should be 12)', f.length);
+    assert.deepEqual(f,
+                     Buffer.from([63, 4, 64, 4, 56, 4, 50, 4, 53, 4, 66, 4]));
+    assert.equal(f.toString(encoding), 'привет');
+  }
+
+  {
+    const f = Buffer.from([0, 0, 0, 0, 0]);
+    assert.equal(f.length, 5);
+    const size = f.write('あいうえお', encoding);
+    console.error('bytes written to buffer: %d     (should be 4)', size);
+    assert.equal(size, 4);
+    assert.deepEqual(f, Buffer.from([0x42, 0x30, 0x44, 0x30, 0x00]));
+  }
+});
+
+{
+  const f = Buffer.from('\uD83D\uDC4D', 'utf-16le'); // THUMBS UP SIGN (U+1F44D)
+  assert.equal(f.length, 4);
+  assert.deepEqual(f, Buffer.from('3DD84DDC', 'hex'));
+}
+
+
+var arrayIsh = {0: 0, 1: 1, 2: 2, 3: 3, length: 4};
+var g = Buffer.from(arrayIsh);
+assert.deepEqual(g, Buffer.from([0, 1, 2, 3]));
+var strArrayIsh = {0: '0', 1: '1', 2: '2', 3: '3', length: 4};
+g = Buffer.from(strArrayIsh);
+assert.deepEqual(g, Buffer.from([0, 1, 2, 3]));
+
+
+//
+// Test toString('base64')
+//
+assert.equal('TWFu', (Buffer.from('Man')).toString('base64'));
+
+{
+  // test that regular and URL-safe base64 both work
+  const expected = [0xff, 0xff, 0xbe, 0xff, 0xef, 0xbf, 0xfb, 0xef, 0xff];
+  assert.deepEqual(Buffer.from('//++/++/++//', 'base64'),
+                   Buffer.from(expected));
+  assert.deepEqual(Buffer.from('__--_--_--__', 'base64'),
+                   Buffer.from(expected));
+}
+
+{
+  // big example
+  const quote = 'Man is distinguished, not only by his reason, but by this ' +
+              'singular passion from other animals, which is a lust ' +
+              'of the mind, that by a perseverance of delight in the ' +
+              'continued and indefatigable generation of knowledge, exceeds ' +
+              'the short vehemence of any carnal pleasure.';
+  const expected = 'TWFuIGlzIGRpc3Rpbmd1aXNoZWQsIG5vdCBvbmx5IGJ5IGhpcyByZWFzb' +
+                 '24sIGJ1dCBieSB0aGlzIHNpbmd1bGFyIHBhc3Npb24gZnJvbSBvdGhlciBh' +
+                 'bmltYWxzLCB3aGljaCBpcyBhIGx1c3Qgb2YgdGhlIG1pbmQsIHRoYXQgYnk' +
+                 'gYSBwZXJzZXZlcmFuY2Ugb2YgZGVsaWdodCBpbiB0aGUgY29udGludWVkIG' +
+                 'FuZCBpbmRlZmF0aWdhYmxlIGdlbmVyYXRpb24gb2Yga25vd2xlZGdlLCBle' +
+                 'GNlZWRzIHRoZSBzaG9ydCB2ZWhlbWVuY2Ugb2YgYW55IGNhcm5hbCBwbGVh' +
+                 'c3VyZS4=';
+  assert.equal(expected, (Buffer.from(quote)).toString('base64'));
+
+  let b = Buffer.allocUnsafe(1024);
+  let bytesWritten = b.write(expected, 0, 'base64');
+  assert.equal(quote.length, bytesWritten);
+  assert.equal(quote, b.toString('ascii', 0, quote.length));
+
+  // check that the base64 decoder ignores whitespace
+  const expectedWhite = expected.slice(0, 60) + ' \n' +
+                      expected.slice(60, 120) + ' \n' +
+                      expected.slice(120, 180) + ' \n' +
+                      expected.slice(180, 240) + ' \n' +
+                      expected.slice(240, 300) + '\n' +
+                      expected.slice(300, 360) + '\n';
+  b = Buffer.allocUnsafe(1024);
+  bytesWritten = b.write(expectedWhite, 0, 'base64');
+  assert.equal(quote.length, bytesWritten);
+  assert.equal(quote, b.toString('ascii', 0, quote.length));
+
+  // check that the base64 decoder on the constructor works
+  // even in the presence of whitespace.
+  b = Buffer.from(expectedWhite, 'base64');
+  assert.equal(quote.length, b.length);
+  assert.equal(quote, b.toString('ascii', 0, quote.length));
+
+  // check that the base64 decoder ignores illegal chars
+  const expectedIllegal = expected.slice(0, 60) + ' \x80' +
+                        expected.slice(60, 120) + ' \xff' +
+                        expected.slice(120, 180) + ' \x00' +
+                        expected.slice(180, 240) + ' \x98' +
+                        expected.slice(240, 300) + '\x03' +
+                        expected.slice(300, 360);
+  b = Buffer.from(expectedIllegal, 'base64');
+  assert.equal(quote.length, b.length);
+  assert.equal(quote, b.toString('ascii', 0, quote.length));
+}
+
+assert.equal(Buffer.from('', 'base64').toString(), '');
+assert.equal(Buffer.from('K', 'base64').toString(), '');
+
+// multiple-of-4 with padding
+assert.equal(Buffer.from('Kg==', 'base64').toString(), '*');
+assert.equal(Buffer.from('Kio=', 'base64').toString(), '**');
+assert.equal(Buffer.from('Kioq', 'base64').toString(), '***');
+assert.equal(Buffer.from('KioqKg==', 'base64').toString(), '****');
+assert.equal(Buffer.from('KioqKio=', 'base64').toString(), '*****');
+assert.equal(Buffer.from('KioqKioq', 'base64').toString(), '******');
+assert.equal(Buffer.from('KioqKioqKg==', 'base64').toString(), '*******');
+assert.equal(Buffer.from('KioqKioqKio=', 'base64').toString(), '********');
+assert.equal(Buffer.from('KioqKioqKioq', 'base64').toString(), '*********');
+assert.equal(Buffer.from('KioqKioqKioqKg==', 'base64').toString(),
+             '**********');
+assert.equal(Buffer.from('KioqKioqKioqKio=', 'base64').toString(),
+             '***********');
+assert.equal(Buffer.from('KioqKioqKioqKioq', 'base64').toString(),
+             '************');
+assert.equal(Buffer.from('KioqKioqKioqKioqKg==', 'base64').toString(),
+             '*************');
+assert.equal(Buffer.from('KioqKioqKioqKioqKio=', 'base64').toString(),
+             '**************');
+assert.equal(Buffer.from('KioqKioqKioqKioqKioq', 'base64').toString(),
+             '***************');
+assert.equal(Buffer.from('KioqKioqKioqKioqKioqKg==', 'base64').toString(),
+             '****************');
+assert.equal(Buffer.from('KioqKioqKioqKioqKioqKio=', 'base64').toString(),
+             '*****************');
+assert.equal(Buffer.from('KioqKioqKioqKioqKioqKioq', 'base64').toString(),
+             '******************');
+assert.equal(Buffer.from('KioqKioqKioqKioqKioqKioqKg==', 'base64').toString(),
+             '*******************');
+assert.equal(Buffer.from('KioqKioqKioqKioqKioqKioqKio=', 'base64').toString(),
+             '********************');
+
+// no padding, not a multiple of 4
+assert.equal(Buffer.from('Kg', 'base64').toString(), '*');
+assert.equal(Buffer.from('Kio', 'base64').toString(), '**');
+assert.equal(Buffer.from('KioqKg', 'base64').toString(), '****');
+assert.equal(Buffer.from('KioqKio', 'base64').toString(), '*****');
+assert.equal(Buffer.from('KioqKioqKg', 'base64').toString(), '*******');
+assert.equal(Buffer.from('KioqKioqKio', 'base64').toString(), '********');
+assert.equal(Buffer.from('KioqKioqKioqKg', 'base64').toString(), '**********');
+assert.equal(Buffer.from('KioqKioqKioqKio', 'base64').toString(),
+             '***********');
+assert.equal(Buffer.from('KioqKioqKioqKioqKg', 'base64').toString(),
+             '*************');
+assert.equal(Buffer.from('KioqKioqKioqKioqKio', 'base64').toString(),
+             '**************');
+assert.equal(Buffer.from('KioqKioqKioqKioqKioqKg', 'base64').toString(),
+             '****************');
+assert.equal(Buffer.from('KioqKioqKioqKioqKioqKio', 'base64').toString(),
+             '*****************');
+assert.equal(Buffer.from('KioqKioqKioqKioqKioqKioqKg', 'base64').toString(),
+             '*******************');
+assert.equal(Buffer.from('KioqKioqKioqKioqKioqKioqKio', 'base64').toString(),
+             '********************');
+
+// handle padding graciously, multiple-of-4 or not
+assert.equal(Buffer.from('72INjkR5fchcxk9+VgdGPFJDxUBFR5/rMFsghgxADiw==',
+                        'base64').length, 32);
+assert.equal(Buffer.from('72INjkR5fchcxk9+VgdGPFJDxUBFR5/rMFsghgxADiw=',
+                        'base64').length, 32);
+assert.equal(Buffer.from('72INjkR5fchcxk9+VgdGPFJDxUBFR5/rMFsghgxADiw',
+                        'base64').length, 32);
+assert.equal(Buffer.from('w69jACy6BgZmaFvv96HG6MYksWytuZu3T1FvGnulPg==',
+                        'base64').length, 31);
+assert.equal(Buffer.from('w69jACy6BgZmaFvv96HG6MYksWytuZu3T1FvGnulPg=',
+                        'base64').length, 31);
+assert.equal(Buffer.from('w69jACy6BgZmaFvv96HG6MYksWytuZu3T1FvGnulPg',
+                        'base64').length, 31);
+
+// This string encodes single '.' character in UTF-16
+var dot = Buffer.from('//4uAA==', 'base64');
+assert.equal(dot[0], 0xff);
+assert.equal(dot[1], 0xfe);
+assert.equal(dot[2], 0x2e);
+assert.equal(dot[3], 0x00);
+assert.equal(dot.toString('base64'), '//4uAA==');
+
+{
+  // Writing base64 at a position > 0 should not mangle the result.
+  //
+  // https://github.com/joyent/node/issues/402
+  const segments = ['TWFkbmVzcz8h', 'IFRoaXM=', 'IGlz', 'IG5vZGUuanMh'];
+  const b = Buffer.allocUnsafe(64);
+  let pos = 0;
+
+  for (let i = 0; i < segments.length; ++i) {
+    pos += b.write(segments[i], pos, 'base64');
+  }
+  assert.equal(b.toString('binary', 0, pos), 'Madness?! This is node.js!');
+}
+
+// Regression test for https://github.com/nodejs/node/issues/3496.
+assert.equal(Buffer.from('=bad'.repeat(1e4), 'base64').length, 0);
+
+{
+  // Creating buffers larger than pool size.
+  const l = Buffer.poolSize + 5;
+  let s = '';
+  for (let i = 0; i < l; i++) {
+    s += 'h';
+  }
+
+  const b = Buffer.from(s);
+
+  for (let i = 0; i < l; i++) {
+    assert.equal('h'.charCodeAt(0), b[i]);
+  }
+
+  const sb = b.toString();
+  assert.equal(sb.length, s.length);
+  assert.equal(sb, s);
+}
+
+{
+  // Single argument slice
+  const b = Buffer.from('abcde');
+  assert.equal('bcde', b.slice(1).toString());
+}
+
+// slice(0,0).length === 0
+assert.equal(0, Buffer.from('hello').slice(0, 0).length);
+
+// test hex toString
+console.log('Create hex string from buffer');
+var hexb = Buffer.allocUnsafe(256);
+for (let i = 0; i < 256; i++) {
+  hexb[i] = i;
+}
+var hexStr = hexb.toString('hex');
+assert.equal(hexStr,
+             '000102030405060708090a0b0c0d0e0f' +
+             '101112131415161718191a1b1c1d1e1f' +
+             '202122232425262728292a2b2c2d2e2f' +
+             '303132333435363738393a3b3c3d3e3f' +
+             '404142434445464748494a4b4c4d4e4f' +
+             '505152535455565758595a5b5c5d5e5f' +
+             '606162636465666768696a6b6c6d6e6f' +
+             '707172737475767778797a7b7c7d7e7f' +
+             '808182838485868788898a8b8c8d8e8f' +
+             '909192939495969798999a9b9c9d9e9f' +
+             'a0a1a2a3a4a5a6a7a8a9aaabacadaeaf' +
+             'b0b1b2b3b4b5b6b7b8b9babbbcbdbebf' +
+             'c0c1c2c3c4c5c6c7c8c9cacbcccdcecf' +
+             'd0d1d2d3d4d5d6d7d8d9dadbdcdddedf' +
+             'e0e1e2e3e4e5e6e7e8e9eaebecedeeef' +
+             'f0f1f2f3f4f5f6f7f8f9fafbfcfdfeff');
+
+console.log('Create buffer from hex string');
+var hexb2 = Buffer.from(hexStr, 'hex');
+for (let i = 0; i < 256; i++) {
+  assert.equal(hexb2[i], hexb[i]);
+}
+
+{
+  // test an invalid slice end.
+  console.log('Try to slice off the end of the buffer');
+  const b = Buffer.from([1, 2, 3, 4, 5]);
+  const b2 = b.toString('hex', 1, 10000);
+  const b3 = b.toString('hex', 1, 5);
+  const b4 = b.toString('hex', 1);
+  assert.equal(b2, b3);
+  assert.equal(b2, b4);
+}
+
+function buildBuffer(data) {
+  if (Array.isArray(data)) {
+    var buffer = Buffer.allocUnsafe(data.length);
+    data.forEach(function(v, k) {
+      buffer[k] = v;
+    });
+    return buffer;
+  }
+  return null;
+}
+
+var x = buildBuffer([0x81, 0xa3, 0x66, 0x6f, 0x6f, 0xa3, 0x62, 0x61, 0x72]);
+
+console.log(x.inspect());
+assert.equal('<Buffer 81 a3 66 6f 6f a3 62 61 72>', x.inspect());
+
+{
+  const z = x.slice(4);
+  console.log(z.inspect());
+  console.log(z.length);
+  assert.equal(5, z.length);
+  assert.equal(0x6f, z[0]);
+  assert.equal(0xa3, z[1]);
+  assert.equal(0x62, z[2]);
+  assert.equal(0x61, z[3]);
+  assert.equal(0x72, z[4]);
+}
+
+{
+  const z = x.slice(0);
+  console.log(z.inspect());
+  console.log(z.length);
+  assert.equal(z.length, x.length);
+}
+
+{
+  const z = x.slice(0, 4);
+  console.log(z.inspect());
+  console.log(z.length);
+  assert.equal(4, z.length);
+  assert.equal(0x81, z[0]);
+  assert.equal(0xa3, z[1]);
+}
+
+{
+  const z = x.slice(0, 9);
+  console.log(z.inspect());
+  console.log(z.length);
+  assert.equal(9, z.length);
+}
+
+{
+  const z = x.slice(1, 4);
+  console.log(z.inspect());
+  console.log(z.length);
+  assert.equal(3, z.length);
+  assert.equal(0xa3, z[0]);
+}
+
+{
+  const z = x.slice(2, 4);
+  console.log(z.inspect());
+  console.log(z.length);
+  assert.equal(2, z.length);
+  assert.equal(0x66, z[0]);
+  assert.equal(0x6f, z[1]);
+}
+
+assert.equal(0, Buffer.from('hello').slice(0, 0).length);
+
+['ucs2', 'ucs-2', 'utf16le', 'utf-16le'].forEach(function(encoding) {
+  const b = Buffer.allocUnsafe(10);
+  b.write('あいうえお', encoding);
+  assert.equal(b.toString(encoding), 'あいうえお');
+});
+
+{
+  // Binary encoding should write only one byte per character.
+  const b = Buffer.from([0xde, 0xad, 0xbe, 0xef]);
+  let s = String.fromCharCode(0xffff);
+  b.write(s, 0, 'binary');
+  assert.equal(0xff, b[0]);
+  assert.equal(0xad, b[1]);
+  assert.equal(0xbe, b[2]);
+  assert.equal(0xef, b[3]);
+  s = String.fromCharCode(0xaaee);
+  b.write(s, 0, 'binary');
+  assert.equal(0xee, b[0]);
+  assert.equal(0xad, b[1]);
+  assert.equal(0xbe, b[2]);
+  assert.equal(0xef, b[3]);
+}
+
+{
+  // #1210 Test UTF-8 string includes null character
+  let buf = Buffer.from('\0');
+  assert.equal(buf.length, 1);
+  buf = Buffer.from('\0\0');
+  assert.equal(buf.length, 2);
+}
+
+{
+  const buf = Buffer.allocUnsafe(2);
+  let written = buf.write(''); // 0byte
+  assert.equal(written, 0);
+  written = buf.write('\0'); // 1byte (v8 adds null terminator)
+  assert.equal(written, 1);
+  written = buf.write('a\0'); // 1byte * 2
+  assert.equal(written, 2);
+  written = buf.write('あ'); // 3bytes
+  assert.equal(written, 0);
+  written = buf.write('\0あ'); // 1byte + 3bytes
+  assert.equal(written, 1);
+  written = buf.write('\0\0あ'); // 1byte * 2 + 3bytes
+  assert.equal(written, 2);
+}
+
+{
+  const buf = Buffer.allocUnsafe(10);
+  written = buf.write('あいう'); // 3bytes * 3 (v8 adds null terminator)
+  assert.equal(written, 9);
+  written = buf.write('あいう\0'); // 3bytes * 3 + 1byte
+  assert.equal(written, 10);
+}
+
+{
+  // #243 Test write() with maxLength
+  const buf = Buffer.allocUnsafe(4);
+  buf.fill(0xFF);
+  let written = buf.write('abcd', 1, 2, 'utf8');
+  console.log(buf);
+  assert.equal(written, 2);
+  assert.equal(buf[0], 0xFF);
+  assert.equal(buf[1], 0x61);
+  assert.equal(buf[2], 0x62);
+  assert.equal(buf[3], 0xFF);
+
+  buf.fill(0xFF);
+  written = buf.write('abcd', 1, 4);
+  console.log(buf);
+  assert.equal(written, 3);
+  assert.equal(buf[0], 0xFF);
+  assert.equal(buf[1], 0x61);
+  assert.equal(buf[2], 0x62);
+  assert.equal(buf[3], 0x63);
+
+  buf.fill(0xFF);
+  written = buf.write('abcd', 'utf8', 1, 2);  // legacy style
+  console.log(buf);
+  assert.equal(written, 2);
+  assert.equal(buf[0], 0xFF);
+  assert.equal(buf[1], 0x61);
+  assert.equal(buf[2], 0x62);
+  assert.equal(buf[3], 0xFF);
+
+  buf.fill(0xFF);
+  written = buf.write('abcdef', 1, 2, 'hex');
+  console.log(buf);
+  assert.equal(written, 2);
+  assert.equal(buf[0], 0xFF);
+  assert.equal(buf[1], 0xAB);
+  assert.equal(buf[2], 0xCD);
+  assert.equal(buf[3], 0xFF);
+
+  ['ucs2', 'ucs-2', 'utf16le', 'utf-16le'].forEach(function(encoding) {
+    buf.fill(0xFF);
+    written = buf.write('abcd', 0, 2, encoding);
+    console.log(buf);
+    assert.equal(written, 2);
+    assert.equal(buf[0], 0x61);
+    assert.equal(buf[1], 0x00);
+    assert.equal(buf[2], 0xFF);
+    assert.equal(buf[3], 0xFF);
+  });
+}
+
+{
+  // test offset returns are correct
+  const b = Buffer.allocUnsafe(16);
+  assert.equal(4, b.writeUInt32LE(0, 0));
+  assert.equal(6, b.writeUInt16LE(0, 4));
+  assert.equal(7, b.writeUInt8(0, 6));
+  assert.equal(8, b.writeInt8(0, 7));
+  assert.equal(16, b.writeDoubleLE(0, 8));
+}
+
+{
+  // test unmatched surrogates not producing invalid utf8 output
+  // ef bf bd = utf-8 representation of unicode replacement character
+  // see https://codereview.chromium.org/121173009/
+  const buf = Buffer.from('ab\ud800cd', 'utf8');
+  assert.equal(buf[0], 0x61);
+  assert.equal(buf[1], 0x62);
+  assert.equal(buf[2], 0xef);
+  assert.equal(buf[3], 0xbf);
+  assert.equal(buf[4], 0xbd);
+  assert.equal(buf[5], 0x63);
+  assert.equal(buf[6], 0x64);
+}
+
+{
+  // test for buffer overrun
+  const buf = Buffer.from([0, 0, 0, 0, 0]); // length: 5
+  var sub = buf.slice(0, 4);         // length: 4
+  written = sub.write('12345', 'binary');
+  assert.equal(written, 4);
+  assert.equal(buf[4], 0);
+}
+
+// Check for fractional length args, junk length args, etc.
+// https://github.com/joyent/node/issues/1758
+
+// Call .fill() first, stops valgrind warning about uninitialized memory reads.
+Buffer.allocUnsafe(3.3).fill().toString();
+// throws bad argument error in commit 43cb4ec
+assert.equal(Buffer.allocUnsafe(-1).length, 0);
+assert.equal(Buffer.allocUnsafe(NaN).length, 0);
+assert.equal(Buffer.allocUnsafe(3.3).length, 3);
+assert.equal(Buffer.from({length: 3.3}).length, 3);
+assert.equal(Buffer.from({length: 'BAM'}).length, 0);
+
+// Make sure that strings are not coerced to numbers.
+assert.equal(Buffer.from('99').length, 2);
+assert.equal(Buffer.from('13.37').length, 5);
+
+// Ensure that the length argument is respected.
+'ascii utf8 hex base64 binary'.split(' ').forEach(function(enc) {
+  assert.equal(Buffer.allocUnsafe(1).write('aaaaaa', 0, 1, enc), 1);
+});
+
+{
+  // Regression test, guard against buffer overrun in the base64 decoder.
+  const a = Buffer.allocUnsafe(3);
+  const b = Buffer.from('xxx');
+  a.write('aaaaaaaa', 'base64');
+  assert.equal(b.toString(), 'xxx');
+}
+
+// issue GH-3416
+Buffer.from(Buffer.alloc(0), 0, 0);
+
+[ 'hex',
+  'utf8',
+  'utf-8',
+  'ascii',
+  'binary',
+  'base64',
+  'ucs2',
+  'ucs-2',
+  'utf16le',
+  'utf-16le' ].forEach(function(enc) {
+    assert.equal(Buffer.isEncoding(enc), true);
+  });
+
+[ 'utf9',
+  'utf-7',
+  'Unicode-FTW',
+  'new gnu gun'  ].forEach(function(enc) {
+    assert.equal(Buffer.isEncoding(enc), false);
+  });
+
+
+// GH-5110
+(function() {
+  const buffer = Buffer.from('test');
+  const string = JSON.stringify(buffer);
+
+  assert.equal(string, '{"type":"Buffer","data":[116,101,115,116]}');
+
+  assert.deepEqual(buffer, JSON.parse(string, function(key, value) {
+    return value && value.type === 'Buffer'
+      ? Buffer.from(value.data)
+      : value;
+  }));
+})();
+
+// issue GH-7849
+(function() {
+  var buf = Buffer.from('test');
+  var json = JSON.stringify(buf);
+  var obj = JSON.parse(json);
+  var copy = Buffer.from(obj);
+
+  assert(buf.equals(copy));
+})();
+
+// issue GH-4331
+assert.throws(function() {
+  Buffer.allocUnsafe(0xFFFFFFFF);
+}, RangeError);
+assert.throws(function() {
+  Buffer.allocUnsafe(0xFFFFFFFFF);
+}, RangeError);
+
+
+// attempt to overflow buffers, similar to previous bug in array buffers
+assert.throws(function() {
+  var buf = Buffer(8);
+  buf.readFloatLE(0xffffffff);
+}, RangeError);
+
+assert.throws(function() {
+  var buf = Buffer.allocUnsafe(8);
+  buf.writeFloatLE(0.0, 0xffffffff);
+}, RangeError);
+
+assert.throws(function() {
+  var buf = Buffer.allocUnsafe(8);
+  buf.readFloatLE(0xffffffff);
+}, RangeError);
+
+assert.throws(function() {
+  var buf = Buffer.allocUnsafe(8);
+  buf.writeFloatLE(0.0, 0xffffffff);
+}, RangeError);
+
+
+// ensure negative values can't get past offset
+assert.throws(function() {
+  var buf = Buffer.allocUnsafe(8);
+  buf.readFloatLE(-1);
+}, RangeError);
+
+assert.throws(function() {
+  var buf = Buffer.allocUnsafe(8);
+  buf.writeFloatLE(0.0, -1);
+}, RangeError);
+
+assert.throws(function() {
+  var buf = Buffer.allocUnsafe(8);
+  buf.readFloatLE(-1);
+}, RangeError);
+
+assert.throws(function() {
+  var buf = Buffer.allocUnsafe(8);
+  buf.writeFloatLE(0.0, -1);
+}, RangeError);
+
+// offset checks
+{
+  const buf = Buffer.alloc(0);
+
+  assert.throws(function() { buf.readUInt8(0); }, RangeError);
+  assert.throws(function() { buf.readInt8(0); }, RangeError);
+}
+
+{
+  const buf = Buffer.from([0xFF]);
+
+  assert.equal(buf.readUInt8(0), 255);
+  assert.equal(buf.readInt8(0), -1);
+}
+
+[16, 32].forEach(function(bits) {
+  var buf = Buffer.allocUnsafe(bits / 8 - 1);
+
+  assert.throws(function() { buf['readUInt' + bits + 'BE'](0); },
+                RangeError,
+                'readUInt' + bits + 'BE');
+
+  assert.throws(function() { buf['readUInt' + bits + 'LE'](0); },
+                RangeError,
+                'readUInt' + bits + 'LE');
+
+  assert.throws(function() { buf['readInt' + bits + 'BE'](0); },
+                RangeError,
+                'readInt' + bits + 'BE()');
+
+  assert.throws(function() { buf['readInt' + bits + 'LE'](0); },
+                RangeError,
+                'readInt' + bits + 'LE()');
+});
+
+[16, 32].forEach(function(bits) {
+  var buf = Buffer.from([0xFF, 0xFF, 0xFF, 0xFF]);
+
+  assert.equal(buf['readUInt' + bits + 'BE'](0),
+                (0xFFFFFFFF >>> (32 - bits)));
+
+  assert.equal(buf['readUInt' + bits + 'LE'](0),
+                (0xFFFFFFFF >>> (32 - bits)));
+
+  assert.equal(buf['readInt' + bits + 'BE'](0),
+                (0xFFFFFFFF >> (32 - bits)));
+
+  assert.equal(buf['readInt' + bits + 'LE'](0),
+                (0xFFFFFFFF >> (32 - bits)));
+});
+
+// test for common read(U)IntLE/BE
+(function() {
+  var buf = Buffer.from([0x01, 0x02, 0x03, 0x04, 0x05, 0x06]);
+
+  assert.equal(buf.readUIntLE(0, 1), 0x01);
+  assert.equal(buf.readUIntBE(0, 1), 0x01);
+  assert.equal(buf.readUIntLE(0, 3), 0x030201);
+  assert.equal(buf.readUIntBE(0, 3), 0x010203);
+  assert.equal(buf.readUIntLE(0, 5), 0x0504030201);
+  assert.equal(buf.readUIntBE(0, 5), 0x0102030405);
+  assert.equal(buf.readUIntLE(0, 6), 0x060504030201);
+  assert.equal(buf.readUIntBE(0, 6), 0x010203040506);
+  assert.equal(buf.readIntLE(0, 1), 0x01);
+  assert.equal(buf.readIntBE(0, 1), 0x01);
+  assert.equal(buf.readIntLE(0, 3), 0x030201);
+  assert.equal(buf.readIntBE(0, 3), 0x010203);
+  assert.equal(buf.readIntLE(0, 5), 0x0504030201);
+  assert.equal(buf.readIntBE(0, 5), 0x0102030405);
+  assert.equal(buf.readIntLE(0, 6), 0x060504030201);
+  assert.equal(buf.readIntBE(0, 6), 0x010203040506);
+})();
+
+// test for common write(U)IntLE/BE
+(function() {
+  var buf = Buffer.allocUnsafe(3);
+  buf.writeUIntLE(0x123456, 0, 3);
+  assert.deepEqual(buf.toJSON().data, [0x56, 0x34, 0x12]);
+  assert.equal(buf.readUIntLE(0, 3), 0x123456);
+
+  buf = Buffer.allocUnsafe(3);
+  buf.writeUIntBE(0x123456, 0, 3);
+  assert.deepEqual(buf.toJSON().data, [0x12, 0x34, 0x56]);
+  assert.equal(buf.readUIntBE(0, 3), 0x123456);
+
+  buf = Buffer.allocUnsafe(3);
+  buf.writeIntLE(0x123456, 0, 3);
+  assert.deepEqual(buf.toJSON().data, [0x56, 0x34, 0x12]);
+  assert.equal(buf.readIntLE(0, 3), 0x123456);
+
+  buf = Buffer.allocUnsafe(3);
+  buf.writeIntBE(0x123456, 0, 3);
+  assert.deepEqual(buf.toJSON().data, [0x12, 0x34, 0x56]);
+  assert.equal(buf.readIntBE(0, 3), 0x123456);
+
+  buf = Buffer.allocUnsafe(3);
+  buf.writeIntLE(-0x123456, 0, 3);
+  assert.deepEqual(buf.toJSON().data, [0xaa, 0xcb, 0xed]);
+  assert.equal(buf.readIntLE(0, 3), -0x123456);
+
+  buf = Buffer.allocUnsafe(3);
+  buf.writeIntBE(-0x123456, 0, 3);
+  assert.deepEqual(buf.toJSON().data, [0xed, 0xcb, 0xaa]);
+  assert.equal(buf.readIntBE(0, 3), -0x123456);
+
+  buf = Buffer.allocUnsafe(3);
+  buf.writeIntLE(-0x123400, 0, 3);
+  assert.deepEqual(buf.toJSON().data, [0x00, 0xcc, 0xed]);
+  assert.equal(buf.readIntLE(0, 3), -0x123400);
+
+  buf = Buffer.allocUnsafe(3);
+  buf.writeIntBE(-0x123400, 0, 3);
+  assert.deepEqual(buf.toJSON().data, [0xed, 0xcc, 0x00]);
+  assert.equal(buf.readIntBE(0, 3), -0x123400);
+
+  buf = Buffer.allocUnsafe(3);
+  buf.writeIntLE(-0x120000, 0, 3);
+  assert.deepEqual(buf.toJSON().data, [0x00, 0x00, 0xee]);
+  assert.equal(buf.readIntLE(0, 3), -0x120000);
+
+  buf = Buffer.allocUnsafe(3);
+  buf.writeIntBE(-0x120000, 0, 3);
+  assert.deepEqual(buf.toJSON().data, [0xee, 0x00, 0x00]);
+  assert.equal(buf.readIntBE(0, 3), -0x120000);
+
+  buf = Buffer.allocUnsafe(5);
+  buf.writeUIntLE(0x1234567890, 0, 5);
+  assert.deepEqual(buf.toJSON().data, [0x90, 0x78, 0x56, 0x34, 0x12]);
+  assert.equal(buf.readUIntLE(0, 5), 0x1234567890);
+
+  buf = Buffer.allocUnsafe(5);
+  buf.writeUIntBE(0x1234567890, 0, 5);
+  assert.deepEqual(buf.toJSON().data, [0x12, 0x34, 0x56, 0x78, 0x90]);
+  assert.equal(buf.readUIntBE(0, 5), 0x1234567890);
+
+  buf = Buffer.allocUnsafe(5);
+  buf.writeIntLE(0x1234567890, 0, 5);
+  assert.deepEqual(buf.toJSON().data, [0x90, 0x78, 0x56, 0x34, 0x12]);
+  assert.equal(buf.readIntLE(0, 5), 0x1234567890);
+
+  buf = Buffer.allocUnsafe(5);
+  buf.writeIntBE(0x1234567890, 0, 5);
+  assert.deepEqual(buf.toJSON().data, [0x12, 0x34, 0x56, 0x78, 0x90]);
+  assert.equal(buf.readIntBE(0, 5), 0x1234567890);
+
+  buf = Buffer.allocUnsafe(5);
+  buf.writeIntLE(-0x1234567890, 0, 5);
+  assert.deepEqual(buf.toJSON().data, [0x70, 0x87, 0xa9, 0xcb, 0xed]);
+  assert.equal(buf.readIntLE(0, 5), -0x1234567890);
+
+  buf = Buffer.allocUnsafe(5);
+  buf.writeIntBE(-0x1234567890, 0, 5);
+  assert.deepEqual(buf.toJSON().data, [0xed, 0xcb, 0xa9, 0x87, 0x70]);
+  assert.equal(buf.readIntBE(0, 5), -0x1234567890);
+
+  buf = Buffer.allocUnsafe(5);
+  buf.writeIntLE(-0x0012000000, 0, 5);
+  assert.deepEqual(buf.toJSON().data, [0x00, 0x00, 0x00, 0xee, 0xff]);
+  assert.equal(buf.readIntLE(0, 5), -0x0012000000);
+
+  buf = Buffer.allocUnsafe(5);
+  buf.writeIntBE(-0x0012000000, 0, 5);
+  assert.deepEqual(buf.toJSON().data, [0xff, 0xee, 0x00, 0x00, 0x00]);
+  assert.equal(buf.readIntBE(0, 5), -0x0012000000);
+})();
+
+// test Buffer slice
+(function() {
+  var buf = Buffer.from('0123456789');
+  assert.equal(buf.slice(-10, 10), '0123456789');
+  assert.equal(buf.slice(-20, 10), '0123456789');
+  assert.equal(buf.slice(-20, -10), '');
+  assert.equal(buf.slice(), '0123456789');
+  assert.equal(buf.slice(0), '0123456789');
+  assert.equal(buf.slice(0, 0), '');
+  assert.equal(buf.slice(undefined), '0123456789');
+  assert.equal(buf.slice('foobar'), '0123456789');
+  assert.equal(buf.slice(undefined, undefined), '0123456789');
+
+  assert.equal(buf.slice(2), '23456789');
+  assert.equal(buf.slice(5), '56789');
+  assert.equal(buf.slice(10), '');
+  assert.equal(buf.slice(5, 8), '567');
+  assert.equal(buf.slice(8, -1), '8');
+  assert.equal(buf.slice(-10), '0123456789');
+  assert.equal(buf.slice(0, -9), '0');
+  assert.equal(buf.slice(0, -10), '');
+  assert.equal(buf.slice(0, -1), '012345678');
+  assert.equal(buf.slice(2, -2), '234567');
+  assert.equal(buf.slice(0, 65536), '0123456789');
+  assert.equal(buf.slice(65536, 0), '');
+  assert.equal(buf.slice(-5, -8), '');
+  assert.equal(buf.slice(-5, -3), '56');
+  assert.equal(buf.slice(-10, 10), '0123456789');
+  for (let i = 0, s = buf.toString(); i < buf.length; ++i) {
+    assert.equal(buf.slice(i), s.slice(i));
+    assert.equal(buf.slice(0, i), s.slice(0, i));
+    assert.equal(buf.slice(-i), s.slice(-i));
+    assert.equal(buf.slice(0, -i), s.slice(0, -i));
+  }
+
+  var utf16Buf = Buffer.from('0123456789', 'utf16le');
+  assert.deepEqual(utf16Buf.slice(0, 6), Buffer.from('012', 'utf16le'));
+
+  assert.equal(buf.slice('0', '1'), '0');
+  assert.equal(buf.slice('-5', '10'), '56789');
+  assert.equal(buf.slice('-10', '10'), '0123456789');
+  assert.equal(buf.slice('-10', '-5'), '01234');
+  assert.equal(buf.slice('-10', '-0'), '');
+  assert.equal(buf.slice('111'), '');
+  assert.equal(buf.slice('0', '-111'), '');
+
+  // try to slice a zero length Buffer
+  // see https://github.com/joyent/node/issues/5881
+  SlowBuffer(0).slice(0, 1);
+})();
+
+// Regression test for #5482: should throw but not assert in C++ land.
+assert.throws(function() {
+  Buffer.from('', 'buffer');
+}, TypeError);
+
+// Regression test for #6111. Constructing a buffer from another buffer
+// should a) work, and b) not corrupt the source buffer.
+(function() {
+  var a = [0];
+  for (let i = 0; i < 7; ++i) a = a.concat(a);
+  a = a.map(function(_, i) { return i; });
+  const b = Buffer.from(a);
+  const c = Buffer.from(b);
+  assert.equal(b.length, a.length);
+  assert.equal(c.length, a.length);
+  for (let i = 0, k = a.length; i < k; ++i) {
+    assert.equal(a[i], i);
+    assert.equal(b[i], i);
+    assert.equal(c[i], i);
+  }
+})();
+
+
+assert.throws(function() {
+  Buffer.allocUnsafe((-1 >>> 0) + 1);
+}, RangeError);
+
+assert.throws(function() {
+  new SlowBuffer((-1 >>> 0) + 1);
+}, RangeError);
+
+if (common.hasCrypto) {
+  // Test truncation after decode
+  var crypto = require('crypto');
+
+  var b1 = Buffer.from('YW55=======', 'base64');
+  var b2 = Buffer.from('YW55', 'base64');
+
+  assert.equal(
+    crypto.createHash('sha1').update(b1).digest('hex'),
+    crypto.createHash('sha1').update(b2).digest('hex')
+  );
+} else {
+  console.log('1..0 # Skipped: missing crypto');
+}
+
+// Test Compare
+{
+  const b = Buffer.alloc(1, 'a');
+  const c = Buffer.alloc(1, 'c');
+  const d = Buffer.alloc(2, 'aa');
+
+  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(b.compare(b), 0);
+
+  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);
+  assert.equal(Buffer.compare(c, c), 0);
+
+  assert.equal(Buffer.compare(Buffer.alloc(0), Buffer.alloc(0)), 0);
+  assert.equal(Buffer.compare(Buffer.alloc(0), Buffer.alloc(1)), -1);
+  assert.equal(Buffer.compare(Buffer.alloc(1), Buffer.alloc(0)), 1);
+}
+
+assert.throws(function() {
+  var b = Buffer.allocUnsafe(1);
+  Buffer.compare(b, 'abc');
+});
+
+assert.throws(function() {
+  var b = Buffer.allocUnsafe(1);
+  Buffer.compare('abc', b);
+});
+
+assert.throws(function() {
+  var b = Buffer.allocUnsafe(1);
+  b.compare('abc');
+});
+
+// Test Equals
+{
+  const b = Buffer.alloc(5, 'abcdf');
+  const c = Buffer.alloc(5, 'abcdf');
+  const d = Buffer.alloc(5, 'abcde');
+  const e = Buffer.alloc(6, 'abcdef');
+
+  assert.ok(b.equals(c));
+  assert.ok(!c.equals(d));
+  assert.ok(!d.equals(e));
+  assert.ok(d.equals(d));
+}
+
+assert.throws(function() {
+  var b = Buffer.allocUnsafe(1);
+  b.equals('abc');
+});
+
+// Regression test for https://github.com/nodejs/node/issues/649.
+assert.throws(function() {
+  Buffer.allocUnsafe(1422561062959).toString('utf8');
+});
+
+var ps = Buffer.poolSize;
+Buffer.poolSize = 0;
+assert.equal(Buffer.allocUnsafe(1).parent, undefined);
+Buffer.poolSize = ps;
+
+// Test Buffer.copy() segfault
+assert.throws(function() {
+  Buffer.allocUnsafe(10).copy();
+});
+
+// Test prototype getters don't throw
+assert.equal(Buffer.prototype.parent, undefined);
+assert.equal(Buffer.prototype.offset, undefined);
+assert.equal(SlowBuffer.prototype.parent, undefined);
+assert.equal(SlowBuffer.prototype.offset, undefined);
diff --git a/test/parallel/test-buffer-safe-unsafe.js b/test/parallel/test-buffer-safe-unsafe.js
new file mode 100644
index 00000000000000..6646f760564432
--- /dev/null
+++ b/test/parallel/test-buffer-safe-unsafe.js
@@ -0,0 +1,14 @@
+'use strict';
+
+require('../common');
+const assert = require('assert');
+
+const safe = Buffer.alloc(10);
+
+function isZeroFilled(buf) {
+  for (let n = 0; n < buf.length; n++)
+    if (buf[n] > 0) return false;
+  return true;
+}
+
+assert(isZeroFilled(safe));