mirror of
https://github.com/balena-io/etcher.git
synced 2025-04-24 23:37:18 +00:00
7c9f15d8a9
Changes: - Split out scanner into own file - Move `lib/shared/sdk` -> `lib/sdk` - Move `lib/image-stream` -> `lib/sdk/image-stream` - Move `lib/writer` -> `lib/sdk/writer` - Rename `sdk/standard` -> `sdk/blockdevice` - Move adapters into `sdk/adapters` subdirectory Change-Type: minor Changelog-Entry: Consolidate low-level components into Etcher SDK
137 lines
3.2 KiB
JavaScript
137 lines
3.2 KiB
JavaScript
/*
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* Copyright 2017 resin.io
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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'use strict'
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const stream = require('readable-stream')
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const debug = require('debug')('block-stream')
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const MIN_BLOCK_SIZE = 512
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const CHUNK_SIZE = 64 * 1024
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/**
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* @summary BlockStream class
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* @class
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*/
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class BlockStream extends stream.Transform {
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/**
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* @summary BlockStream constructor
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* @param {Object} [options] - options
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* @param {Number} [options.blockSize] - block size in bytes
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* @param {Number} [options.chunkSize] - chunk size in bytes
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* @example
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* new BlockStream(options)
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*/
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constructor (options) {
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options = Object.assign({}, BlockStream.defaults, options)
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options.readableObjectMode = true
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super(options)
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this.blockSize = options.blockSize
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this.chunkSize = options.chunkSize
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this.bytesRead = 0
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this.bytesWritten = 0
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this._buffers = []
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this._bytes = 0
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debug('new %j', options)
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}
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/**
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* @summary Internal write handler
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* @private
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* @param {Buffer} chunk - chunk buffer
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* @param {String} encoding - chunk encoding
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* @param {Function} next - callback(error, value)
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* @example
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* // Not to be called directly
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*/
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_transform (chunk, encoding, next) {
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this.bytesRead += chunk.length
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if (this._bytes === 0 && chunk.length >= this.chunkSize) {
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if (chunk.length % this.blockSize === 0) {
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this.bytesWritten += chunk.length
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this.push(chunk)
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next()
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return
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}
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}
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this._buffers.push(chunk)
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this._bytes += chunk.length
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if (this._bytes >= this.chunkSize) {
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let block = Buffer.concat(this._buffers)
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const length = Math.floor(block.length / this.blockSize) * this.blockSize
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this._buffers.length = 0
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this._bytes = 0
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if (block.length !== length) {
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this._buffers.push(block.slice(length))
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this._bytes += block.length - length
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block = block.slice(0, length)
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}
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this.bytesWritten += block.length
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this.push(block)
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}
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next()
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}
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/**
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* @summary Internal stream end handler
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* @private
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* @param {Function} done - callback(error, value)
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* @example
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* // Not to be called directly
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*/
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_flush (done) {
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if (!this._bytes) {
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done()
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return
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}
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const length = Math.ceil(this._bytes / this.blockSize) * this.blockSize
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const block = Buffer.alloc(length)
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let offset = 0
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for (let index = 0; index < this._buffers.length; index += 1) {
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this._buffers[index].copy(block, offset)
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offset += this._buffers[index].length
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}
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this.push(block)
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done()
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}
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}
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/**
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* @summary Default options
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* @type {Object}
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* @constant
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*/
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BlockStream.defaults = {
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blockSize: MIN_BLOCK_SIZE,
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chunkSize: CHUNK_SIZE
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}
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module.exports = BlockStream
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