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108 lines
3.1 KiB
108 lines
3.1 KiB
2 years ago
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/*
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MIT License http://www.opensource.org/licenses/mit-license.php
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Author Tobias Koppers @sokra
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*/
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"use strict";
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const fs = require("fs");
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const path = require("path");
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// macOS, Linux, and Windows all rely on these errors
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const EXPECTED_ERRORS = new Set(["EINVAL", "ENOENT"]);
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// On Windows there is also this error in some cases
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if (process.platform === "win32") EXPECTED_ERRORS.add("UNKNOWN");
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class LinkResolver {
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constructor() {
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this.cache = new Map();
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}
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/**
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* @param {string} file path to file or directory
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* @returns {string[]} array of file and all symlinks contributed in the resolving process (first item is the resolved file)
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*/
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resolve(file) {
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const cacheEntry = this.cache.get(file);
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if (cacheEntry !== undefined) {
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return cacheEntry;
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}
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const parent = path.dirname(file);
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if (parent === file) {
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// At root of filesystem there can't be a link
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const result = Object.freeze([file]);
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this.cache.set(file, result);
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return result;
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}
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// resolve the parent directory to find links there and get the real path
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const parentResolved = this.resolve(parent);
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let realFile = file;
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// is the parent directory really somewhere else?
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if (parentResolved[0] !== parent) {
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// get the real location of file
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const basename = path.basename(file);
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realFile = path.resolve(parentResolved[0], basename);
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}
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// try to read the link content
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try {
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const linkContent = fs.readlinkSync(realFile);
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// resolve the link content relative to the parent directory
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const resolvedLink = path.resolve(parentResolved[0], linkContent);
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// recursive resolve the link content for more links in the structure
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const linkResolved = this.resolve(resolvedLink);
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// merge parent and link resolve results
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let result;
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if (linkResolved.length > 1 && parentResolved.length > 1) {
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// when both contain links we need to duplicate them with a Set
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const resultSet = new Set(linkResolved);
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// add the link
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resultSet.add(realFile);
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// add all symlinks of the parent
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for (let i = 1; i < parentResolved.length; i++) {
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resultSet.add(parentResolved[i]);
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}
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result = Object.freeze(Array.from(resultSet));
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} else if (parentResolved.length > 1) {
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// we have links in the parent but not for the link content location
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result = parentResolved.slice();
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result[0] = linkResolved[0];
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// add the link
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result.push(realFile);
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Object.freeze(result);
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} else if (linkResolved.length > 1) {
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// we can return the link content location result
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result = linkResolved.slice();
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// add the link
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result.push(realFile);
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Object.freeze(result);
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} else {
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// neither link content location nor parent have links
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// this link is the only link here
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result = Object.freeze([
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// the resolve real location
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linkResolved[0],
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// add the link
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realFile
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]);
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}
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this.cache.set(file, result);
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return result;
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} catch (e) {
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if (!EXPECTED_ERRORS.has(e.code)) {
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throw e;
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}
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// no link
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const result = parentResolved.slice();
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result[0] = realFile;
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Object.freeze(result);
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this.cache.set(file, result);
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return result;
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}
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}
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}
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module.exports = LinkResolver;
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