397 lines
9.3 KiB
JavaScript
397 lines
9.3 KiB
JavaScript
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'use strict'
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const { Buffer } = require('buffer')
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const symbol = Symbol.for('BufferList')
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function BufferList (buf) {
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if (!(this instanceof BufferList)) {
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return new BufferList(buf)
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}
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BufferList._init.call(this, buf)
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}
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BufferList._init = function _init (buf) {
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Object.defineProperty(this, symbol, { value: true })
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this._bufs = []
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this.length = 0
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if (buf) {
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this.append(buf)
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}
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}
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BufferList.prototype._new = function _new (buf) {
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return new BufferList(buf)
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}
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BufferList.prototype._offset = function _offset (offset) {
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if (offset === 0) {
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return [0, 0]
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}
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let tot = 0
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for (let i = 0; i < this._bufs.length; i++) {
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const _t = tot + this._bufs[i].length
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if (offset < _t || i === this._bufs.length - 1) {
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return [i, offset - tot]
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}
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tot = _t
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}
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}
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BufferList.prototype._reverseOffset = function (blOffset) {
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const bufferId = blOffset[0]
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let offset = blOffset[1]
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for (let i = 0; i < bufferId; i++) {
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offset += this._bufs[i].length
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}
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return offset
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}
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BufferList.prototype.get = function get (index) {
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if (index > this.length || index < 0) {
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return undefined
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}
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const offset = this._offset(index)
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return this._bufs[offset[0]][offset[1]]
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}
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BufferList.prototype.slice = function slice (start, end) {
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if (typeof start === 'number' && start < 0) {
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start += this.length
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}
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if (typeof end === 'number' && end < 0) {
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end += this.length
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}
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return this.copy(null, 0, start, end)
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}
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BufferList.prototype.copy = function copy (dst, dstStart, srcStart, srcEnd) {
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if (typeof srcStart !== 'number' || srcStart < 0) {
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srcStart = 0
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}
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if (typeof srcEnd !== 'number' || srcEnd > this.length) {
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srcEnd = this.length
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}
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if (srcStart >= this.length) {
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return dst || Buffer.alloc(0)
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}
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if (srcEnd <= 0) {
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return dst || Buffer.alloc(0)
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}
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const copy = !!dst
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const off = this._offset(srcStart)
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const len = srcEnd - srcStart
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let bytes = len
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let bufoff = (copy && dstStart) || 0
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let start = off[1]
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// copy/slice everything
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if (srcStart === 0 && srcEnd === this.length) {
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if (!copy) {
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// slice, but full concat if multiple buffers
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return this._bufs.length === 1
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? this._bufs[0]
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: Buffer.concat(this._bufs, this.length)
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}
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// copy, need to copy individual buffers
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for (let i = 0; i < this._bufs.length; i++) {
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this._bufs[i].copy(dst, bufoff)
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bufoff += this._bufs[i].length
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}
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return dst
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}
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// easy, cheap case where it's a subset of one of the buffers
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if (bytes <= this._bufs[off[0]].length - start) {
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return copy
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? this._bufs[off[0]].copy(dst, dstStart, start, start + bytes)
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: this._bufs[off[0]].slice(start, start + bytes)
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}
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if (!copy) {
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// a slice, we need something to copy in to
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dst = Buffer.allocUnsafe(len)
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}
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for (let i = off[0]; i < this._bufs.length; i++) {
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const l = this._bufs[i].length - start
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if (bytes > l) {
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this._bufs[i].copy(dst, bufoff, start)
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bufoff += l
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} else {
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this._bufs[i].copy(dst, bufoff, start, start + bytes)
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bufoff += l
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break
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}
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bytes -= l
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if (start) {
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start = 0
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}
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}
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// safeguard so that we don't return uninitialized memory
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if (dst.length > bufoff) return dst.slice(0, bufoff)
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return dst
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}
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BufferList.prototype.shallowSlice = function shallowSlice (start, end) {
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start = start || 0
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end = typeof end !== 'number' ? this.length : end
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if (start < 0) {
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start += this.length
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}
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if (end < 0) {
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end += this.length
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}
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if (start === end) {
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return this._new()
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}
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const startOffset = this._offset(start)
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const endOffset = this._offset(end)
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const buffers = this._bufs.slice(startOffset[0], endOffset[0] + 1)
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if (endOffset[1] === 0) {
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buffers.pop()
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} else {
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buffers[buffers.length - 1] = buffers[buffers.length - 1].slice(0, endOffset[1])
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}
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if (startOffset[1] !== 0) {
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buffers[0] = buffers[0].slice(startOffset[1])
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}
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return this._new(buffers)
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}
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BufferList.prototype.toString = function toString (encoding, start, end) {
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return this.slice(start, end).toString(encoding)
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}
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BufferList.prototype.consume = function consume (bytes) {
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// first, normalize the argument, in accordance with how Buffer does it
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bytes = Math.trunc(bytes)
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// do nothing if not a positive number
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if (Number.isNaN(bytes) || bytes <= 0) return this
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while (this._bufs.length) {
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if (bytes >= this._bufs[0].length) {
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bytes -= this._bufs[0].length
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this.length -= this._bufs[0].length
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this._bufs.shift()
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} else {
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this._bufs[0] = this._bufs[0].slice(bytes)
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this.length -= bytes
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break
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}
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}
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return this
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}
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BufferList.prototype.duplicate = function duplicate () {
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const copy = this._new()
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for (let i = 0; i < this._bufs.length; i++) {
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copy.append(this._bufs[i])
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}
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return copy
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}
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BufferList.prototype.append = function append (buf) {
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if (buf == null) {
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return this
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}
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if (buf.buffer) {
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// append a view of the underlying ArrayBuffer
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this._appendBuffer(Buffer.from(buf.buffer, buf.byteOffset, buf.byteLength))
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} else if (Array.isArray(buf)) {
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for (let i = 0; i < buf.length; i++) {
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this.append(buf[i])
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}
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} else if (this._isBufferList(buf)) {
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// unwrap argument into individual BufferLists
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for (let i = 0; i < buf._bufs.length; i++) {
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this.append(buf._bufs[i])
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}
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} else {
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// coerce number arguments to strings, since Buffer(number) does
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// uninitialized memory allocation
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if (typeof buf === 'number') {
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buf = buf.toString()
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}
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this._appendBuffer(Buffer.from(buf))
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}
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return this
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}
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BufferList.prototype._appendBuffer = function appendBuffer (buf) {
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this._bufs.push(buf)
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this.length += buf.length
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}
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BufferList.prototype.indexOf = function (search, offset, encoding) {
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if (encoding === undefined && typeof offset === 'string') {
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encoding = offset
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offset = undefined
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}
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if (typeof search === 'function' || Array.isArray(search)) {
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throw new TypeError('The "value" argument must be one of type string, Buffer, BufferList, or Uint8Array.')
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} else if (typeof search === 'number') {
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search = Buffer.from([search])
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} else if (typeof search === 'string') {
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search = Buffer.from(search, encoding)
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} else if (this._isBufferList(search)) {
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search = search.slice()
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} else if (Array.isArray(search.buffer)) {
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search = Buffer.from(search.buffer, search.byteOffset, search.byteLength)
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} else if (!Buffer.isBuffer(search)) {
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search = Buffer.from(search)
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}
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offset = Number(offset || 0)
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if (isNaN(offset)) {
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offset = 0
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}
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if (offset < 0) {
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offset = this.length + offset
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}
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if (offset < 0) {
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offset = 0
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}
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if (search.length === 0) {
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return offset > this.length ? this.length : offset
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}
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const blOffset = this._offset(offset)
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let blIndex = blOffset[0] // index of which internal buffer we're working on
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let buffOffset = blOffset[1] // offset of the internal buffer we're working on
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// scan over each buffer
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for (; blIndex < this._bufs.length; blIndex++) {
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const buff = this._bufs[blIndex]
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while (buffOffset < buff.length) {
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const availableWindow = buff.length - buffOffset
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if (availableWindow >= search.length) {
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const nativeSearchResult = buff.indexOf(search, buffOffset)
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if (nativeSearchResult !== -1) {
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return this._reverseOffset([blIndex, nativeSearchResult])
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}
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buffOffset = buff.length - search.length + 1 // end of native search window
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} else {
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const revOffset = this._reverseOffset([blIndex, buffOffset])
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if (this._match(revOffset, search)) {
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return revOffset
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}
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buffOffset++
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}
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}
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buffOffset = 0
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}
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return -1
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}
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BufferList.prototype._match = function (offset, search) {
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if (this.length - offset < search.length) {
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return false
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}
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for (let searchOffset = 0; searchOffset < search.length; searchOffset++) {
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if (this.get(offset + searchOffset) !== search[searchOffset]) {
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return false
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}
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}
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return true
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}
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;(function () {
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const methods = {
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readDoubleBE: 8,
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readDoubleLE: 8,
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readFloatBE: 4,
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readFloatLE: 4,
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readInt32BE: 4,
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readInt32LE: 4,
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readUInt32BE: 4,
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readUInt32LE: 4,
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readInt16BE: 2,
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readInt16LE: 2,
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readUInt16BE: 2,
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readUInt16LE: 2,
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readInt8: 1,
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readUInt8: 1,
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readIntBE: null,
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readIntLE: null,
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readUIntBE: null,
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readUIntLE: null
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}
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for (const m in methods) {
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(function (m) {
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if (methods[m] === null) {
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BufferList.prototype[m] = function (offset, byteLength) {
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return this.slice(offset, offset + byteLength)[m](0, byteLength)
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}
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} else {
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BufferList.prototype[m] = function (offset = 0) {
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return this.slice(offset, offset + methods[m])[m](0)
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}
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}
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}(m))
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}
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}())
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// Used internally by the class and also as an indicator of this object being
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// a `BufferList`. It's not possible to use `instanceof BufferList` in a browser
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// environment because there could be multiple different copies of the
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// BufferList class and some `BufferList`s might be `BufferList`s.
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BufferList.prototype._isBufferList = function _isBufferList (b) {
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return b instanceof BufferList || BufferList.isBufferList(b)
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}
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BufferList.isBufferList = function isBufferList (b) {
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return b != null && b[symbol]
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}
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module.exports = BufferList
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