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d8e31665a0
- Extend the `standard` ESLint configuration - Remove ESLint rules that are defined in the `standard` configuration - Get rid of semi-colons See: https://github.com/resin-io/etcher/pull/1657 Signed-off-by: Juan Cruz Viotti <jv@jviotti.com>
90 lines
2.6 KiB
JavaScript
90 lines
2.6 KiB
JavaScript
/*
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* Copyright 2016 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 Bluebird = require('bluebird')
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const fs = Bluebird.promisifyAll(require('fs'))
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const errors = require('../shared/errors')
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/**
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* @summary Read a buffer from an image file descriptor
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* @function
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* @private
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*
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* @param {Number} fileDescriptor - file descriptor
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* @param {Number} position - image position to start reading from
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* @param {Number} count - number of bytes to read
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* @fulfil {Buffer} - buffer
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* @returns {Promise}
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*
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* @example
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* fs.openAsync('path/to/image.img', 'r').then((fileDescriptor) => {
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* return utils.readBufferFromImageFileDescriptor(fileDescriptor, 0, 512);
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* }).then((buffer) => {
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* console.log(buffer);
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* });
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*/
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exports.readBufferFromImageFileDescriptor = (fileDescriptor, position, count) => {
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const BUFFER_FILL_VALUE = 0
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const BUFFER_START_POSITION = 0
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const buffer = Buffer.alloc(count, BUFFER_FILL_VALUE)
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return fs.readAsync(fileDescriptor, buffer, BUFFER_START_POSITION, count, position).tap((bytesRead) => {
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if (bytesRead !== count) {
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throw errors.createUserError({
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title: 'Looks like the image is truncated',
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description: `We tried to read ${count} bytes at ${position}, but got ${bytesRead} bytes instead`
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})
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}
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}).return(buffer)
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}
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/**
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* @summary Extract the data of a readable stream
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* @function
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* @public
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*
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* @description
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* You should be careful when using this function, since you can only
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* extract files that are not bigger than the available computer memory.
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*
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* @param {StreamReadable} stream - stream
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* @fulfil {Buffer} - data
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* @returns {Promise}
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*
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* @example
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* const stream = fs.createReadStream('./foo/bar');
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*
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* utils.extractStream(stream).then((data) => {
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* console.log(data.toString());
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* });
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*/
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exports.extractStream = (stream) => {
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return new Bluebird((resolve, reject) => {
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const chunks = []
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stream.on('data', (chunk) => {
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chunks.push(chunk)
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})
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stream.on('error', reject)
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stream.on('end', () => {
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resolve(Buffer.concat(chunks))
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})
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})
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}
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