Cameron Kaiser c9b2922b70 hello FPR
2017-04-19 00:56:45 -07:00

352 lines
11 KiB
JavaScript

/* 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);
}
});
});