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buffer.js
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buffer.js
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/**
* @module Buffer
*
* The buffer module from node.js, for the browser.
*
* @author Feross Aboukhadijeh <https://feross.org>
* @license MIT
*
* @see {@link https://nodejs.org/api/buffer.html#buffer_class_buffer}
*/
/* eslint-disable no-proto */
import console from './console.js'
const base64 = {
toByteArray,
fromByteArray
}
const lookup = []
const revLookup = []
const Arr = typeof Uint8Array !== 'undefined' ? Uint8Array : Array
const code = 'ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/'
for (let i = 0, len = code.length; i < len; ++i) {
lookup[i] = code[i]
revLookup[code.charCodeAt(i)] = i
}
// Support decoding URL-safe base64 strings, as Node.js does.
// See: https://en.wikipedia.org/wiki/Base64#URL_applications
revLookup['-'.charCodeAt(0)] = 62
revLookup['_'.charCodeAt(0)] = 63
function getLens (b64) {
const len = b64.length
if (len % 4 > 0) {
throw new Error('Invalid string. Length must be a multiple of 4')
}
// Trim off extra bytes after placeholder bytes are found
// See: https://github.com/beatgammit/base64-js/issues/42
let validLen = b64.indexOf('=')
if (validLen === -1) validLen = len
const placeHoldersLen = validLen === len
? 0
: 4 - (validLen % 4)
return [validLen, placeHoldersLen]
}
function _byteLength (b64, validLen, placeHoldersLen) {
return ((validLen + placeHoldersLen) * 3 / 4) - placeHoldersLen
}
function toByteArray (b64) {
let tmp
const lens = getLens(b64)
const validLen = lens[0]
const placeHoldersLen = lens[1]
const arr = new Arr(_byteLength(b64, validLen, placeHoldersLen))
let curByte = 0
// if there are placeholders, only get up to the last complete 4 chars
const len = placeHoldersLen > 0
? validLen - 4
: validLen
let i
for (i = 0; i < len; i += 4) {
tmp =
(revLookup[b64.charCodeAt(i)] << 18) |
(revLookup[b64.charCodeAt(i + 1)] << 12) |
(revLookup[b64.charCodeAt(i + 2)] << 6) |
revLookup[b64.charCodeAt(i + 3)]
arr[curByte++] = (tmp >> 16) & 0xFF
arr[curByte++] = (tmp >> 8) & 0xFF
arr[curByte++] = tmp & 0xFF
}
if (placeHoldersLen === 2) {
tmp =
(revLookup[b64.charCodeAt(i)] << 2) |
(revLookup[b64.charCodeAt(i + 1)] >> 4)
arr[curByte++] = tmp & 0xFF
}
if (placeHoldersLen === 1) {
tmp =
(revLookup[b64.charCodeAt(i)] << 10) |
(revLookup[b64.charCodeAt(i + 1)] << 4) |
(revLookup[b64.charCodeAt(i + 2)] >> 2)
arr[curByte++] = (tmp >> 8) & 0xFF
arr[curByte++] = tmp & 0xFF
}
return arr
}
function tripletToBase64 (num) {
return lookup[num >> 18 & 0x3F] +
lookup[num >> 12 & 0x3F] +
lookup[num >> 6 & 0x3F] +
lookup[num & 0x3F]
}
function encodeChunk (uint8, start, end) {
let tmp
const output = []
for (let i = start; i < end; i += 3) {
tmp =
((uint8[i] << 16) & 0xFF0000) +
((uint8[i + 1] << 8) & 0xFF00) +
(uint8[i + 2] & 0xFF)
output.push(tripletToBase64(tmp))
}
return output.join('')
}
function fromByteArray (uint8) {
let tmp
const len = uint8.length
const extraBytes = len % 3 // if we have 1 byte left, pad 2 bytes
const parts = []
const maxChunkLength = 16383 // must be multiple of 3
// go through the array every three bytes, we'll deal with trailing stuff later
for (let i = 0, len2 = len - extraBytes; i < len2; i += maxChunkLength) {
parts.push(encodeChunk(uint8, i, (i + maxChunkLength) > len2 ? len2 : (i + maxChunkLength)))
}
// pad the end with zeros, but make sure to not forget the extra bytes
if (extraBytes === 1) {
tmp = uint8[len - 1]
parts.push(
lookup[tmp >> 2] +
lookup[(tmp << 4) & 0x3F] +
'=='
)
} else if (extraBytes === 2) {
tmp = (uint8[len - 2] << 8) + uint8[len - 1]
parts.push(
lookup[tmp >> 10] +
lookup[(tmp >> 4) & 0x3F] +
lookup[(tmp << 2) & 0x3F] +
'='
)
}
return parts.join('')
}
const ieee754 = {}
/*! ieee754. BSD-3-Clause License. Feross Aboukhadijeh <https://feross.org/opensource> */
ieee754.read = function (buffer, offset, isLE, mLen, nBytes) {
let e, m
const eLen = (nBytes * 8) - mLen - 1
const eMax = (1 << eLen) - 1
const eBias = eMax >> 1
let nBits = -7
let i = isLE ? (nBytes - 1) : 0
const d = isLE ? -1 : 1
let s = buffer[offset + i]
i += d
e = s & ((1 << (-nBits)) - 1)
s >>= (-nBits)
nBits += eLen
while (nBits > 0) {
e = (e * 256) + buffer[offset + i]
i += d
nBits -= 8
}
m = e & ((1 << (-nBits)) - 1)
e >>= (-nBits)
nBits += mLen
while (nBits > 0) {
m = (m * 256) + buffer[offset + i]
i += d
nBits -= 8
}
if (e === 0) {
e = 1 - eBias
} else if (e === eMax) {
return m ? NaN : ((s ? -1 : 1) * Infinity)
} else {
m = m + Math.pow(2, mLen)
e = e - eBias
}
return (s ? -1 : 1) * m * Math.pow(2, e - mLen)
}
ieee754.write = function (buffer, value, offset, isLE, mLen, nBytes) {
let e, m, c
let eLen = (nBytes * 8) - mLen - 1
const eMax = (1 << eLen) - 1
const eBias = eMax >> 1
const rt = (mLen === 23 ? Math.pow(2, -24) - Math.pow(2, -77) : 0)
let i = isLE ? 0 : (nBytes - 1)
const d = isLE ? 1 : -1
const s = value < 0 || (value === 0 && 1 / value < 0) ? 1 : 0
value = Math.abs(value)
if (isNaN(value) || value === Infinity) {
m = isNaN(value) ? 1 : 0
e = eMax
} else {
e = Math.floor(Math.log(value) / Math.LN2)
if (value * (c = Math.pow(2, -e)) < 1) {
e--
c *= 2
}
if (e + eBias >= 1) {
value += rt / c
} else {
value += rt * Math.pow(2, 1 - eBias)
}
if (value * c >= 2) {
e++
c /= 2
}
if (e + eBias >= eMax) {
m = 0
e = eMax
} else if (e + eBias >= 1) {
m = ((value * c) - 1) * Math.pow(2, mLen)
e = e + eBias
} else {
m = value * Math.pow(2, eBias - 1) * Math.pow(2, mLen)
e = 0
}
}
while (mLen >= 8) {
buffer[offset + i] = m & 0xff
i += d
m /= 256
mLen -= 8
}
e = (e << mLen) | m
eLen += mLen
while (eLen > 0) {
buffer[offset + i] = e & 0xff
i += d
e /= 256
eLen -= 8
}
buffer[offset + i - d] |= s * 128
}
//
// Buffer module
//
const customInspectSymbol =
(typeof Symbol === 'function' && typeof Symbol['for'] === 'function') // eslint-disable-line dot-notation
? Symbol['for']('nodejs.util.inspect.custom') // eslint-disable-line dot-notation
: null
const INSPECT_MAX_BYTES = 50
const K_MAX_LENGTH = 0x7fffffff
const kMaxLength = K_MAX_LENGTH
export default Buffer
export {
Buffer,
SlowBuffer,
INSPECT_MAX_BYTES,
kMaxLength
}
/**
* If `Buffer.TYPED_ARRAY_SUPPORT`:
* === true Use Uint8Array implementation (fastest)
* === false Print warning and recommend using `buffer` v4.x which has an Object
* implementation (most compatible, even IE6)
*
* Browsers that support typed arrays are IE 10+, Firefox 4+, Chrome 7+, Safari 5.1+,
* Opera 11.6+, iOS 4.2+.
*
* We report that the browser does not support typed arrays if the are not subclassable
* using __proto__. Firefox 4-29 lacks support for adding new properties to `Uint8Array`
* (See: https://bugzilla.mozilla.org/show_bug.cgi?id=695438). IE 10 lacks support
* for __proto__ and has a buggy typed array implementation.
*/
Buffer.TYPED_ARRAY_SUPPORT = typedArraySupport()
if (!Buffer.TYPED_ARRAY_SUPPORT && typeof console !== 'undefined' &&
typeof console.error === 'function') {
console.error(
'This browser lacks typed array (Uint8Array) support which is required by ' +
'`buffer` v5.x. Use `buffer` v4.x if you require old browser support.'
)
}
function typedArraySupport () {
// Can typed array instances can be augmented?
try {
const arr = new Uint8Array(1)
const proto = { foo: function () { return 42 } }
Object.setPrototypeOf(proto, Uint8Array.prototype)
Object.setPrototypeOf(arr, proto)
return arr.foo() === 42
} catch (e) {
return false
}
}
Object.defineProperty(Buffer.prototype, 'parent', {
enumerable: true,
get: function () {
if (!Buffer.isBuffer(this)) return undefined
return this.buffer
}
})
Object.defineProperty(Buffer.prototype, 'offset', {
enumerable: true,
get: function () {
if (!Buffer.isBuffer(this)) return undefined
return this.byteOffset
}
})
function createBuffer (length) {
if (length > K_MAX_LENGTH) {
throw new RangeError('The value "' + length + '" is invalid for option "size"')
}
// Return an augmented `Uint8Array` instance
const buf = new Uint8Array(length)
Object.setPrototypeOf(buf, Buffer.prototype)
return buf
}
/**
* The Buffer constructor returns instances of `Uint8Array` that have their
* prototype changed to `Buffer.prototype`. Furthermore, `Buffer` is a subclass of
* `Uint8Array`, so the returned instances will have all the node `Buffer` methods
* and the `Uint8Array` methods. Square bracket notation works as expected -- it
* returns a single octet.
*
* The `Uint8Array` prototype remains unmodified.
*/
function Buffer (arg, encodingOrOffset, length) {
// Common case.
if (typeof arg === 'number') {
if (typeof encodingOrOffset === 'string') {
throw new TypeError(
'The "string" argument must be of type string. Received type number'
)
}
return allocUnsafe(arg)
}
return from(arg, encodingOrOffset, length)
}
Buffer.poolSize = 8192 // not used by this implementation
function from (value, encodingOrOffset, length) {
if (typeof value === 'string') {
return fromString(value, encodingOrOffset)
}
if (ArrayBuffer.isView(value)) {
return fromArrayView(value)
}
if (value == null) {
throw new TypeError(
'The first argument must be one of type string, Buffer, ArrayBuffer, Array, ' +
'or Array-like Object. Received type ' + (typeof value)
)
}
if (isInstance(value, ArrayBuffer) ||
(value && isInstance(value.buffer, ArrayBuffer))) {
return fromArrayBuffer(value, encodingOrOffset, length)
}
if (typeof SharedArrayBuffer !== 'undefined' &&
(isInstance(value, SharedArrayBuffer) ||
(value && isInstance(value.buffer, SharedArrayBuffer)))) {
return fromArrayBuffer(value, encodingOrOffset, length)
}
if (typeof value === 'number') {
throw new TypeError(
'The "value" argument must not be of type number. Received type number'
)
}
const valueOf = value.valueOf && value.valueOf()
if (valueOf != null && valueOf !== value) {
return Buffer.from(valueOf, encodingOrOffset, length)
}
const b = fromObject(value)
if (b) return b
if (typeof Symbol !== 'undefined' && Symbol.toPrimitive != null &&
typeof value[Symbol.toPrimitive] === 'function') {
return Buffer.from(value[Symbol.toPrimitive]('string'), encodingOrOffset, length)
}
throw new TypeError(
'The first argument must be one of type string, Buffer, ArrayBuffer, Array, ' +
'or Array-like Object. Received type ' + (typeof value)
)
}
/**
* 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) {
return from(value, encodingOrOffset, length)
}
// Note: Change prototype *after* Buffer.from is defined to workaround Chrome bug:
// https://github.com/feross/buffer/pull/148
Object.setPrototypeOf(Buffer.prototype, Uint8Array.prototype)
Object.setPrototypeOf(Buffer, Uint8Array)
function assertSize (size) {
if (typeof size !== 'number') {
throw new TypeError('"size" argument must be of type number')
} else if (size < 0) {
throw new RangeError('The value "' + size + '" is invalid for option "size"')
}
}
function alloc (size, fill, encoding) {
assertSize(size)
if (size <= 0) {
return createBuffer(size)
}
if (fill !== undefined) {
// Only pay attention to encoding if it's a string. This
// prevents accidentally sending in a number that would
// be interpreted as a start offset.
return typeof encoding === 'string'
? createBuffer(size).fill(fill, encoding)
: createBuffer(size).fill(fill)
}
return createBuffer(size)
}
/**
* Creates a new filled Buffer instance.
* alloc(size[, fill[, encoding]])
**/
Buffer.alloc = function (size, fill, encoding) {
return alloc(size, fill, encoding)
}
function allocUnsafe (size) {
assertSize(size)
return createBuffer(size < 0 ? 0 : checked(size) | 0)
}
/**
* Equivalent to Buffer(num), by default creates a non-zero-filled Buffer instance.
* */
Buffer.allocUnsafe = function (size) {
return allocUnsafe(size)
}
/**
* Equivalent to SlowBuffer(num), by default creates a non-zero-filled Buffer instance.
*/
Buffer.allocUnsafeSlow = function (size) {
return allocUnsafe(size)
}
function fromString (string, encoding) {
if (typeof encoding !== 'string' || encoding === '') {
encoding = 'utf8'
}
if (!Buffer.isEncoding(encoding)) {
throw new TypeError('Unknown encoding: ' + encoding)
}
const length = byteLength(string, encoding) | 0
let buf = createBuffer(length)
const actual = buf.write(string, encoding)
if (actual !== length) {
// Writing a hex string, for example, that contains invalid characters will
// cause everything after the first invalid character to be ignored. (e.g.
// 'abxxcd' will be treated as 'ab')
buf = buf.slice(0, actual)
}
return buf
}
function fromArrayLike (array) {
const length = array.length < 0 ? 0 : checked(array.length) | 0
const buf = createBuffer(length)
for (let i = 0; i < length; i += 1) {
buf[i] = array[i] & 255
}
return buf
}
function fromArrayView (arrayView) {
if (isInstance(arrayView, Uint8Array)) {
const copy = new Uint8Array(arrayView)
return fromArrayBuffer(copy.buffer, copy.byteOffset, copy.byteLength)
}
return fromArrayLike(arrayView)
}
function fromArrayBuffer (array, byteOffset, length) {
if (byteOffset < 0 || array.byteLength < byteOffset) {
throw new RangeError('"offset" is outside of buffer bounds')
}
if (array.byteLength < byteOffset + (length || 0)) {
throw new RangeError('"length" is outside of buffer bounds')
}
let buf
if (byteOffset === undefined && length === undefined) {
buf = new Uint8Array(array)
} else if (length === undefined) {
buf = new Uint8Array(array, byteOffset)
} else {
buf = new Uint8Array(array, byteOffset, length)
}
// Return an augmented `Uint8Array` instance
Object.setPrototypeOf(buf, Buffer.prototype)
return buf
}
function fromObject (obj) {
if (Buffer.isBuffer(obj)) {
const len = checked(obj.length) | 0
const buf = createBuffer(len)
if (buf.length === 0) {
return buf
}
obj.copy(buf, 0, 0, len)
return buf
}
if (obj.length !== undefined) {
if (typeof obj.length !== 'number' || numberIsNaN(obj.length)) {
return createBuffer(0)
}
return fromArrayLike(obj)
}
if (obj.type === 'Buffer' && Array.isArray(obj.data)) {
return fromArrayLike(obj.data)
}
}
function checked (length) {
// Note: cannot use `length < K_MAX_LENGTH` here because that fails when
// length is NaN (which is otherwise coerced to zero.)
if (length >= K_MAX_LENGTH) {
throw new RangeError('Attempt to allocate Buffer larger than maximum ' +
'size: 0x' + K_MAX_LENGTH.toString(16) + ' bytes')
}
return length | 0
}
function SlowBuffer (length) {
if (+length != length) { // eslint-disable-line eqeqeq
length = 0
}
return Buffer.alloc(+length)
}
Buffer.isBuffer = function isBuffer (b) {
return b != null && b._isBuffer === true &&
b !== Buffer.prototype // so Buffer.isBuffer(Buffer.prototype) will be false
}
Buffer.compare = function compare (a, b) {
if (isInstance(a, Uint8Array)) a = Buffer.from(a, a.offset, a.byteLength)
if (isInstance(b, Uint8Array)) b = Buffer.from(b, b.offset, b.byteLength)
if (!Buffer.isBuffer(a) || !Buffer.isBuffer(b)) {
throw new TypeError(
'The "buf1", "buf2" arguments must be one of type Buffer or Uint8Array'
)
}
if (a === b) return 0
let x = a.length
let y = b.length
for (let i = 0, len = Math.min(x, y); i < len; ++i) {
if (a[i] !== b[i]) {
x = a[i]
y = b[i]
break
}
}
if (x < y) return -1
if (y < x) return 1
return 0
}
Buffer.isEncoding = function isEncoding (encoding) {
switch (String(encoding).toLowerCase()) {
case 'hex':
case 'utf8':
case 'utf-8':
case 'ascii':
case 'latin1':
case 'binary':
case 'base64':
case 'ucs2':
case 'ucs-2':
case 'utf16le':
case 'utf-16le':
return true
default:
return false
}
}
Buffer.concat = function concat (list, length) {
if (!Array.isArray(list)) {
throw new TypeError('"list" argument must be an Array of Buffers')
}
if (list.length === 0) {
return Buffer.alloc(0)
}
let i
if (length === undefined) {
length = 0
for (i = 0; i < list.length; ++i) {
length += list[i].length
}
}
const buffer = Buffer.allocUnsafe(length)
let pos = 0
for (i = 0; i < list.length; ++i) {
let buf = list[i]
if (isInstance(buf, Uint8Array)) {
if (pos + buf.length > buffer.length) {
if (!Buffer.isBuffer(buf)) {
buf = Buffer.from(buf.buffer, buf.byteOffset, buf.byteLength)
}
buf.copy(buffer, pos)
} else {
Uint8Array.prototype.set.call(
buffer,
buf,
pos
)
}
} else if (!Buffer.isBuffer(buf)) {
throw new TypeError('"list" argument must be an Array of Buffers')
} else {
buf.copy(buffer, pos)
}
pos += buf.length
}
return buffer
}
function byteLength (string, encoding) {
if (Buffer.isBuffer(string)) {
return string.length
}
if (ArrayBuffer.isView(string) || isInstance(string, ArrayBuffer)) {
return string.byteLength
}
if (typeof string !== 'string') {
throw new TypeError(
'The "string" argument must be one of type string, Buffer, or ArrayBuffer. ' +
'Received type ' + typeof string
)
}
const len = string.length
const mustMatch = (arguments.length > 2 && arguments[2] === true)
if (!mustMatch && len === 0) return 0
// Use a for loop to avoid recursion
let loweredCase = false
for (;;) {
switch (encoding) {
case 'ascii':
case 'latin1':
case 'binary':
return len
case 'utf8':
case 'utf-8':
return utf8ToBytes(string).length
case 'ucs2':
case 'ucs-2':
case 'utf16le':
case 'utf-16le':
return len * 2
case 'hex':
return len >>> 1
case 'base64':
return base64ToBytes(string).length
default:
if (loweredCase) {
return mustMatch ? -1 : utf8ToBytes(string).length // assume utf8
}
encoding = ('' + encoding).toLowerCase()
loweredCase = true
}
}
}
Buffer.byteLength = byteLength
function slowToString (encoding, start, end) {
let loweredCase = false
// No need to verify that "this.length <= MAX_UINT32" since it's a read-only
// property of a typed array.
// This behaves neither like String nor Uint8Array in that we set start/end
// to their upper/lower bounds if the value passed is out of range.
// undefined is handled specially as per ECMA-262 6th Edition,
// Section 13.3.3.7 Runtime Semantics: KeyedBindingInitialization.
if (start === undefined || start < 0) {
start = 0
}
// Return early if start > this.length. Done here to prevent potential uint32
// coercion fail below.
if (start > this.length) {
return ''
}
if (end === undefined || end > this.length) {
end = this.length
}
if (end <= 0) {
return ''
}
// Force coercion to uint32. This will also coerce falsey/NaN values to 0.
end >>>= 0
start >>>= 0
if (end <= start) {
return ''
}
if (!encoding) encoding = 'utf8'
while (true) {
switch (encoding) {
case 'hex':
return hexSlice(this, start, end)
case 'utf8':
case 'utf-8':
return utf8Slice(this, start, end)
case 'ascii':
return asciiSlice(this, start, end)
case 'latin1':
case 'binary':
return latin1Slice(this, start, end)
case 'base64':
return base64Slice(this, start, end)
case 'ucs2':
case 'ucs-2':
case 'utf16le':
case 'utf-16le':
return utf16leSlice(this, start, end)
default:
if (loweredCase) throw new TypeError('Unknown encoding: ' + encoding)
encoding = (encoding + '').toLowerCase()
loweredCase = true
}
}
}
// This property is used by `Buffer.isBuffer` (and the `is-buffer` npm package)
// to detect a Buffer instance. It's not possible to use `instanceof Buffer`
// reliably in a browserify context because there could be multiple different
// copies of the 'buffer' package in use. This method works even for Buffer
// instances that were created from another copy of the `buffer` package.
// See: https://github.com/feross/buffer/issues/154
Buffer.prototype._isBuffer = true
function swap (b, n, m) {
const i = b[n]
b[n] = b[m]
b[m] = i
}
Buffer.prototype.swap16 = function swap16 () {
const len = this.length
if (len % 2 !== 0) {
throw new RangeError('Buffer size must be a multiple of 16-bits')
}
for (let i = 0; i < len; i += 2) {
swap(this, i, i + 1)
}
return this
}
Buffer.prototype.swap32 = function swap32 () {
const len = this.length
if (len % 4 !== 0) {
throw new RangeError('Buffer size must be a multiple of 32-bits')
}
for (let i = 0; i < len; i += 4) {
swap(this, i, i + 3)
swap(this, i + 1, i + 2)
}
return this
}
Buffer.prototype.swap64 = function swap64 () {
const len = this.length
if (len % 8 !== 0) {
throw new RangeError('Buffer size must be a multiple of 64-bits')
}
for (let i = 0; i < len; i += 8) {
swap(this, i, i + 7)
swap(this, i + 1, i + 6)
swap(this, i + 2, i + 5)
swap(this, i + 3, i + 4)
}
return this
}
Buffer.prototype.toString = function toString () {
const length = this.length
if (length === 0) return ''
if (arguments.length === 0) return utf8Slice(this, 0, length)
return slowToString.apply(this, arguments)
}
Buffer.prototype.toLocaleString = Buffer.prototype.toString
Buffer.prototype.equals = function equals (b) {
if (!Buffer.isBuffer(b)) throw new TypeError('Argument must be a Buffer')
if (this === b) return true
return Buffer.compare(this, b) === 0
}
Buffer.prototype.inspect = function inspect () {
let str = ''
const max = INSPECT_MAX_BYTES
str = this.toString('hex', 0, max).replace(/(.{2})/g, '$1 ').trim()
if (this.length > max) str += ' ... '
return '<Buffer ' + str + '>'
}
if (customInspectSymbol) {
Buffer.prototype[customInspectSymbol] = Buffer.prototype.inspect
}
Buffer.prototype.compare = function compare (target, start, end, thisStart, thisEnd) {
if (isInstance(target, Uint8Array)) {
target = Buffer.from(target, target.offset, target.byteLength)
}
if (!Buffer.isBuffer(target)) {
throw new TypeError(
'The "target" argument must be one of type Buffer or Uint8Array. ' +
'Received type ' + (typeof target)
)
}
if (start === undefined) {
start = 0
}
if (end === undefined) {
end = target ? target.length : 0
}
if (thisStart === undefined) {
thisStart = 0
}
if (thisEnd === undefined) {
thisEnd = this.length
}
if (start < 0 || end > target.length || thisStart < 0 || thisEnd > this.length) {
throw new RangeError('out of range index')
}
if (thisStart >= thisEnd && start >= end) {
return 0
}
if (thisStart >= thisEnd) {
return -1
}
if (start >= end) {
return 1
}
start >>>= 0
end >>>= 0
thisStart >>>= 0
thisEnd >>>= 0
if (this === target) return 0
let x = thisEnd - thisStart
let y = end - start
const len = Math.min(x, y)
const thisCopy = this.slice(thisStart, thisEnd)
const targetCopy = target.slice(start, end)
for (let i = 0; i < len; ++i) {
if (thisCopy[i] !== targetCopy[i]) {
x = thisCopy[i]
y = targetCopy[i]
break
}
}
if (x < y) return -1
if (y < x) return 1
return 0
}
// Finds either the first index of `val` in `buffer` at offset >= `byteOffset`,
// OR the last index of `val` in `buffer` at offset <= `byteOffset`.
//
// Arguments:
// - buffer - a Buffer to search
// - val - a string, Buffer, or number
// - byteOffset - an index into `buffer`; will be clamped to an int32
// - encoding - an optional encoding, relevant is val is a string
// - dir - true for indexOf, false for lastIndexOf
function bidirectionalIndexOf (buffer, val, byteOffset, encoding, dir) {
// Empty buffer means no match
if (buffer.length === 0) return -1
// Normalize byteOffset
if (typeof byteOffset === 'string') {
encoding = byteOffset
byteOffset = 0
} else if (byteOffset > 0x7fffffff) {
byteOffset = 0x7fffffff
} else if (byteOffset < -0x80000000) {
byteOffset = -0x80000000
}
byteOffset = +byteOffset // Coerce to Number.
if (numberIsNaN(byteOffset)) {
// byteOffset: it it's undefined, null, NaN, "foo", etc, search whole buffer
byteOffset = dir ? 0 : (buffer.length - 1)
}
// Normalize byteOffset: negative offsets start from the end of the buffer
if (byteOffset < 0) byteOffset = buffer.length + byteOffset
if (byteOffset >= buffer.length) {
if (dir) return -1
else byteOffset = buffer.length - 1
} else if (byteOffset < 0) {
if (dir) byteOffset = 0
else return -1
}
// Normalize val
if (typeof val === 'string') {
val = Buffer.from(val, encoding)
}
// Finally, search either indexOf (if dir is true) or lastIndexOf
if (Buffer.isBuffer(val)) {
// Special case: looking for empty string/buffer always fails
if (val.length === 0) {