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- var toString = Object.prototype.toString
-
- var isModern = (
- typeof Buffer.alloc === 'function' &&
- typeof Buffer.allocUnsafe === 'function' &&
- typeof Buffer.from === 'function'
- )
-
- function isArrayBuffer (input) {
- return toString.call(input).slice(8, -1) === 'ArrayBuffer'
- }
-
- function fromArrayBuffer (obj, byteOffset, length) {
- byteOffset >>>= 0
-
- var maxLength = obj.byteLength - byteOffset
-
- if (maxLength < 0) {
- throw new RangeError("'offset' is out of bounds")
- }
-
- if (length === undefined) {
- length = maxLength
- } else {
- length >>>= 0
-
- if (length > maxLength) {
- throw new RangeError("'length' is out of bounds")
- }
- }
-
- return isModern
- ? Buffer.from(obj.slice(byteOffset, byteOffset + length))
- : new Buffer(new Uint8Array(obj.slice(byteOffset, byteOffset + length)))
- }
-
- 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')
- }
-
- return isModern
- ? Buffer.from(string, encoding)
- : new Buffer(string, encoding)
- }
-
- function bufferFrom (value, encodingOrOffset, length) {
- if (typeof value === 'number') {
- throw new TypeError('"value" argument must not be a number')
- }
-
- if (isArrayBuffer(value)) {
- return fromArrayBuffer(value, encodingOrOffset, length)
- }
-
- if (typeof value === 'string') {
- return fromString(value, encodingOrOffset)
- }
-
- return isModern
- ? Buffer.from(value)
- : new Buffer(value)
- }
-
- module.exports = bufferFrom
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