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37b7ea3b0a
This is a small refactoring commit that extracts the MIME related function from utils.js into a new file called mime.js, and stores the default image MIME type there as a constant, to avoid duplicating it in multiple parts of the code. Change-Type: patch Signed-off-by: Juan Cruz Viotti <jv@jviotti.com>
66 lines
1.8 KiB
JavaScript
66 lines
1.8 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 _ = require('lodash');
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const Bluebird = require('bluebird');
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const fileType = require('file-type');
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const mime = require('mime-types');
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const fs = require('fs');
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/**
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* @summary The default MIME type
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* @type {String}
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* @constant
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*/
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exports.DEFAULT_MIME_TYPE = 'application/octet-stream';
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/**
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* @summary Get file's mime type, by reading the initial 262 bytes if necessary
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* @function
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* @public
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*
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* @param {String} filename - file path
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* @fulfil {String} - mime type
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* @returns {Promise}
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*
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* @example
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* mime.getMimeTypeFromFileName('path/to/raspberrypi.img.gz').then((mimeType) => {
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* console.log(mimeType);
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* });
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*/
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exports.getMimeTypeFromFileName = (filename) => {
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const mimeType = mime.lookup(filename);
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if (mimeType) {
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return Bluebird.resolve(mimeType);
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}
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const FILE_TYPE_ID_BYTES = 262;
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return Bluebird.using(fs.openAsync(filename, 'r').disposer((fileDescriptor) => {
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return fs.closeAsync(fileDescriptor);
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}), (fileDescriptor) => {
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const BUFFER_START = 0;
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const buffer = Buffer.alloc(FILE_TYPE_ID_BYTES);
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return fs.readAsync(fileDescriptor, buffer, BUFFER_START, FILE_TYPE_ID_BYTES, null).then(() => {
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return _.get(fileType(buffer), [ 'mime' ], exports.DEFAULT_MIME_TYPE);
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});
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});
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};
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