1 files changed, 351 insertions, 0 deletions
diff --git a/toolkit/jetpack/sdk/io/buffer.js b/toolkit/jetpack/sdk/io/buffer.js
new file mode 100644
index 000000000..5ea169402
--- /dev/null
+++ b/toolkit/jetpack/sdk/io/buffer.js
@@ -0,0 +1,351 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+'use strict';
+
+module.metadata = {
+  'stability': 'experimental'
+};
+
+/*
+ * Encodings supported by TextEncoder/Decoder:
+ * utf-8, utf-16le, utf-16be
+ * http://encoding.spec.whatwg.org/#interface-textencoder
+ *
+ * Node however supports the following encodings:
+ * ascii, utf-8, utf-16le, usc2, base64, hex
+ */
+
+const { Cu } = require('chrome');
+const { isNumber } = require('sdk/lang/type');
+const { TextEncoder, TextDecoder } = Cu.import('resource://gre/modules/commonjs/toolkit/loader.js', {});
+
+exports.TextEncoder = TextEncoder;
+exports.TextDecoder = TextDecoder;
+
+/**
+ * Use WeakMaps to work around Bug 929146, which prevents us from adding
+ * getters or values to typed arrays
+ * https://bugzilla.mozilla.org/show_bug.cgi?id=929146
+ */
+const parents = new WeakMap();
+const views = new WeakMap();
+
+function Buffer(subject, encoding /*, bufferLength */) {
+
+  // Allow invocation without `new` constructor
+  if (!(this instanceof Buffer))
+    return new Buffer(subject, encoding, arguments[2]);
+
+  var type = typeof(subject);
+
+  switch (type) {
+    case 'number':
+      // Create typed array of the given size if number.
+      try {
+        let buffer = new Uint8Array(subject > 0 ? Math.floor(subject) : 0);
+        return buffer;
+      } catch (e) {
+        if (/size and count too large/.test(e.message) ||
+            /invalid arguments/.test(e.message))
+          throw new RangeError('Could not instantiate buffer: size of buffer may be too large');
+        else
+          throw new Error('Could not instantiate buffer');
+      }
+      break;
+    case 'string':
+      // If string encode it and use buffer for the returned Uint8Array
+      // to create a local patched version that acts like node buffer.
+      encoding = encoding || 'utf8';
+      return new Uint8Array(new TextEncoder(encoding).encode(subject).buffer);
+    case 'object':
+      // This form of the constructor uses the form of
+      // new Uint8Array(buffer, offset, length);
+      // So we can instantiate a typed array within the constructor
+      // to inherit the appropriate properties, where both the
+      // `subject` and newly instantiated buffer share the same underlying
+      // data structure.
+      if (arguments.length === 3)
+        return new Uint8Array(subject, encoding, arguments[2]);
+      // If array or alike just make a copy with a local patched prototype.
+      else
+        return new Uint8Array(subject);
+    default:
+      throw new TypeError('must start with number, buffer, array or string');
+  }
+}
+exports.Buffer = Buffer;
+
+// Tests if `value` is a Buffer.
+Buffer.isBuffer = value => value instanceof Buffer
+
+// Returns true if the encoding is a valid encoding argument & false otherwise
+Buffer.isEncoding = function (encoding) {
+  if (!encoding) return false;
+  try {
+    new TextDecoder(encoding);
+  } catch(e) {
+    return false;
+  }
+  return true;
+}
+
+// Gives the actual byte length of a string. encoding defaults to 'utf8'.
+// This is not the same as String.prototype.length since that returns the
+// number of characters in a string.
+Buffer.byteLength = (value, encoding = 'utf8') =>
+  new TextEncoder(encoding).encode(value).byteLength
+
+// Direct copy of the nodejs's buffer implementation:
+// https://github.com/joyent/node/blob/b255f4c10a80343f9ce1cee56d0288361429e214/lib/buffer.js#L146-L177
+Buffer.concat = function(list, length) {
+  if (!Array.isArray(list))
+    throw new TypeError('Usage: Buffer.concat(list[, length])');
+
+  if (typeof length === 'undefined') {
+    length = 0;
+    for (var i = 0; i < list.length; i++)
+      length += list[i].length;
+  } else {
+    length = ~~length;
+  }
+
+  if (length < 0)
+    length = 0;
+
+  if (list.length === 0)
+    return new Buffer(0);
+  else if (list.length === 1)
+    return list[0];
+
+  if (length < 0)
+    throw new RangeError('length is not a positive number');
+
+  var buffer = new Buffer(length);
+  var pos = 0;
+  for (var i = 0; i < list.length; i++) {
+    var buf = list[i];
+    buf.copy(buffer, pos);
+    pos += buf.length;
+  }
+
+  return buffer;
+};
+
+// Node buffer is very much like Uint8Array although it has bunch of methods
+// that typically can be used in combination with `DataView` while preserving
+// access by index. Since in SDK each module has it's own set of bult-ins it
+// ok to patch ours to make it nodejs Buffer compatible.
+const Uint8ArraySet = Uint8Array.prototype.set
+Buffer.prototype = Uint8Array.prototype;
+Object.defineProperties(Buffer.prototype, {
+  parent: {
+    get: function() { return parents.get(this, undefined); }
+  },
+  view: {
+    get: function () {
+      let view = views.get(this, undefined);
+      if (view) return view;
+      view = new DataView(this.buffer);
+      views.set(this, view);
+      return view;
+    }
+  },
+  toString: {
+    value: function(encoding, start, end) {
+      encoding = !!encoding ? (encoding + '').toLowerCase() : 'utf8';
+      start = Math.max(0, ~~start);
+      end = Math.min(this.length, end === void(0) ? this.length : ~~end);
+      return new TextDecoder(encoding).decode(this.subarray(start, end));
+    }
+  },
+  toJSON: {
+    value: function() {
+      return { type: 'Buffer', data: Array.slice(this, 0) };
+    }
+  },
+  get: {
+    value: function(offset) {
+      return this[offset];
+    }
+  },
+  set: {
+    value: function(offset, value) { this[offset] = value; }
+  },
+  copy: {
+    value: function(target, offset, start, end) {
+      let length = this.length;
+      let targetLength = target.length;
+      offset = isNumber(offset) ? offset : 0;
+      start = isNumber(start) ? start : 0;
+
+      if (start < 0)
+        throw new RangeError('sourceStart is outside of valid range');
+      if (end < 0)
+        throw new RangeError('sourceEnd is outside of valid range');
+
+      // If sourceStart > sourceEnd, or targetStart > targetLength,
+      // zero bytes copied
+      if (start > end ||
+          offset > targetLength
+          )
+        return 0;
+
+      // If `end` is not defined, or if it is defined
+      // but would overflow `target`, redefine `end`
+      // so we can copy as much as we can
+      if (end - start > targetLength - offset ||
+          end == null) {
+        let remainingTarget = targetLength - offset;
+        let remainingSource = length - start;
+        if (remainingSource <= remainingTarget)
+          end = length;
+        else
+          end = start + remainingTarget;
+      }
+
+      Uint8ArraySet.call(target, this.subarray(start, end), offset);
+      return end - start;
+    }
+  },
+  slice: {
+    value: function(start, end) {
+      let length = this.length;
+      start = ~~start;
+      end = end != null ? end : length;
+
+      if (start < 0) {
+        start += length;
+        if (start < 0) start = 0;
+      } else if (start > length)
+        start = length;
+
+      if (end < 0) {
+        end += length;
+        if (end < 0) end = 0;
+      } else if (end > length)
+        end = length;
+
+      if (end < start)
+        end = start;
+
+      // This instantiation uses the new Uint8Array(buffer, offset, length) version
+      // of construction to share the same underling data structure
+      let buffer = new Buffer(this.buffer, start, end - start);
+
+      // If buffer has a value, assign its parent value to the
+      // buffer it shares its underlying structure with. If a slice of
+      // a slice, then use the root structure
+      if (buffer.length > 0)
+        parents.set(buffer, this.parent || this);
+
+      return buffer;
+    }
+  },
+  write: {
+    value: function(string, offset, length, encoding = 'utf8') {
+      // write(string, encoding);
+      if (typeof(offset) === 'string' && Number.isNaN(parseInt(offset))) {
+        [offset, length, encoding] = [0, null, offset];
+      }
+      // write(string, offset, encoding);
+      else if (typeof(length) === 'string')
+        [length, encoding] = [null, length];
+
+      if (offset < 0 || offset > this.length)
+        throw new RangeError('offset is outside of valid range');
+
+      offset = ~~offset;
+
+      // Clamp length if it would overflow buffer, or if its
+      // undefined
+      if (length == null || length + offset > this.length)
+        length = this.length - offset;
+
+      let buffer = new TextEncoder(encoding).encode(string);
+      let result = Math.min(buffer.length, length);
+      if (buffer.length !== length)
+        buffer = buffer.subarray(0, length);
+
+      Uint8ArraySet.call(this, buffer, offset);
+      return result;
+    }
+  },
+  fill: {
+    value: function fill(value, start, end) {
+      let length = this.length;
+      value = value || 0;
+      start = start || 0;
+      end = end || length;
+
+      if (typeof(value) === 'string')
+        value = value.charCodeAt(0);
+      if (typeof(value) !== 'number' || isNaN(value))
+        throw TypeError('value is not a number');
+      if (end < start)
+        throw new RangeError('end < start');
+
+      // Fill 0 bytes; we're done
+      if (end === start)
+        return 0;
+      if (length == 0)
+        return 0;
+
+      if (start < 0 || start >= length)
+        throw RangeError('start out of bounds');
+
+      if (end < 0 || end > length)
+        throw RangeError('end out of bounds');
+
+      let index = start;
+      while (index < end) this[index++] = value;
+    }
+  }
+});
+
+// Define nodejs Buffer's getter and setter functions that just proxy
+// to internal DataView's equivalent methods.
+
+// TODO do we need to check architecture to see if it's default big/little endian?
+[['readUInt16LE', 'getUint16', true],
+ ['readUInt16BE', 'getUint16', false],
+ ['readInt16LE', 'getInt16', true],
+ ['readInt16BE', 'getInt16', false],
+ ['readUInt32LE', 'getUint32', true],
+ ['readUInt32BE', 'getUint32', false],
+ ['readInt32LE', 'getInt32', true],
+ ['readInt32BE', 'getInt32', false],
+ ['readFloatLE', 'getFloat32', true],
+ ['readFloatBE', 'getFloat32', false],
+ ['readDoubleLE', 'getFloat64', true],
+ ['readDoubleBE', 'getFloat64', false],
+ ['readUInt8', 'getUint8'],
+ ['readInt8', 'getInt8']].forEach(([alias, name, littleEndian]) => {
+  Object.defineProperty(Buffer.prototype, alias, {
+    value: function(offset) {
+      return this.view[name](offset, littleEndian);
+    }
+  });
+});
+
+[['writeUInt16LE', 'setUint16', true],
+ ['writeUInt16BE', 'setUint16', false],
+ ['writeInt16LE', 'setInt16', true],
+ ['writeInt16BE', 'setInt16', false],
+ ['writeUInt32LE', 'setUint32', true],
+ ['writeUInt32BE', 'setUint32', false],
+ ['writeInt32LE', 'setInt32', true],
+ ['writeInt32BE', 'setInt32', false],
+ ['writeFloatLE', 'setFloat32', true],
+ ['writeFloatBE', 'setFloat32', false],
+ ['writeDoubleLE', 'setFloat64', true],
+ ['writeDoubleBE', 'setFloat64', false],
+ ['writeUInt8', 'setUint8'],
+ ['writeInt8', 'setInt8']].forEach(([alias, name, littleEndian]) => {
+  Object.defineProperty(Buffer.prototype, alias, {
+    value: function(value, offset) {
+      return this.view[name](offset, value, littleEndian);
+    }
+  });
+});