Juan Cruz Viotti d8e31665a0 chore: follow standardjs guidelines (#1664)
- 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>
2017-08-03 09:01:54 -04:00

65 lines
1.8 KiB
JavaScript

/*
* Copyright 2017 resin.io
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
'use strict'
const _ = require('lodash')
const Bluebird = require('bluebird')
const fs = Bluebird.promisifyAll(require('fs'))
const fileType = require('file-type')
const mime = require('mime-types')
const utils = require('./utils')
/**
* @summary The default MIME type
* @type {String}
* @constant
*/
exports.DEFAULT_MIME_TYPE = 'application/octet-stream'
/**
* @summary Get file's mime type, by reading the initial 262 bytes if necessary
* @function
* @public
*
* @param {String} filename - file path
* @fulfil {String} - mime type
* @returns {Promise}
*
* @example
* mime.getMimeTypeFromFileName('path/to/raspberrypi.img.gz').then((mimeType) => {
* console.log(mimeType);
* });
*/
exports.getMimeTypeFromFileName = (filename) => {
const mimeType = mime.lookup(filename)
if (mimeType) {
return Bluebird.resolve(mimeType)
}
const FILE_TYPE_ID_START = 0
const FILE_TYPE_ID_BYTES = 262
return Bluebird.using(fs.openAsync(filename, 'r').disposer((fileDescriptor) => {
return fs.closeAsync(fileDescriptor)
}), (fileDescriptor) => {
return utils.readBufferFromImageFileDescriptor(fileDescriptor, FILE_TYPE_ID_START, FILE_TYPE_ID_BYTES).then((buffer) => {
return _.get(fileType(buffer), [ 'mime' ], exports.DEFAULT_MIME_TYPE)
})
})
}