58 lines
1.3 KiB
JavaScript
58 lines
1.3 KiB
JavaScript
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const {statSync, createReadStream} = require('fs');
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const Blob = require('./index.js');
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const DOMException = require('domexception');
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/**
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* @param {string} path filepath on the disk
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* @returns {Blob}
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*/
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function blobFrom(path) {
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const {size, mtime} = statSync(path);
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const blob = new BlobDataItem({path, size, mtime});
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return new Blob([blob]);
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}
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/**
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* This is a blob backed up by a file on the disk
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* with minium requirement
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*
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* @private
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*/
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class BlobDataItem {
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constructor(options) {
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this.size = options.size;
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this.path = options.path;
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this.start = options.start;
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this.mtime = options.mtime;
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}
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// Slicing arguments is first validated and formated
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// to not be out of range by Blob.prototype.slice
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slice(start, end) {
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return new BlobDataItem({
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path: this.path,
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start,
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mtime: this.mtime,
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size: end - start
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});
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}
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stream() {
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if (statSync(this.path).mtime > this.mtime) {
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throw new DOMException('The requested file could not be read, typically due to permission problems that have occurred after a reference to a file was acquired.', 'NotReadableError');
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}
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return createReadStream(this.path, {
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start: this.start,
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end: this.start + this.size - 1
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});
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}
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get [Symbol.toStringTag]() {
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return 'Blob';
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}
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}
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module.exports = blobFrom;
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