90 lines
2.6 KiB
JavaScript
90 lines
2.6 KiB
JavaScript
require("isomorphic-fetch");
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const fs = require("fs");
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const path = require("path");
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const tmpdir = require("os-tmpdir");
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const gunzip = require("gunzip-maybe");
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const mkdirp = require("mkdirp");
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const tar = require("tar-fs");
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const createMutex = require("./createMutex");
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function createTempPath(name, version) {
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const normalName = name.replace(/\//g, "-");
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return path.join(tmpdir(), `unpkg-${normalName}-${version}`);
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}
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function stripNamePrefix(headers) {
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// Most packages have header names that look like "package/index.js"
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// so we shorten that to just "index.js" here. A few packages use a
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// prefix other than "package/". e.g. the firebase package uses the
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// "firebase_npm/" prefix. So we just strip the first dir name.
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headers.name = headers.name.replace(/^[^/]+\//, "");
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return headers;
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}
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function ignoreLinks(file, headers) {
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return headers.type === "link" || headers.type === "symlink";
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}
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function extractResponse(response, outputDir) {
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return new Promise((resolve, reject) => {
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const extract = tar.extract(outputDir, {
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readable: true, // All dirs/files should be readable.
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map: stripNamePrefix,
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ignore: ignoreLinks
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});
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response.body
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.pipe(gunzip())
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.pipe(extract)
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.on("finish", resolve)
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.on("error", reject);
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});
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}
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function fetchAndExtract(tarballURL, outputDir) {
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console.log(`info: Fetching ${tarballURL} and extracting to ${outputDir}`);
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return fetch(tarballURL).then(response => {
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return extractResponse(response, outputDir);
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});
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}
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const fetchMutex = createMutex((payload, callback) => {
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const { tarballURL, outputDir } = payload;
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fs.access(outputDir, function(error) {
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if (error) {
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if (error.code === "ENOENT" || error.code === "ENOTDIR") {
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// ENOENT or ENOTDIR are to be expected when we haven't yet
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// fetched a package for the first time. Carry on!
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mkdirp(outputDir, function(error) {
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if (error) {
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callback(error);
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} else {
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fetchAndExtract(tarballURL, outputDir).then(() => {
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callback();
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}, callback);
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}
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});
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} else {
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callback(error);
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}
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} else {
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// Best case: we already have this package cached on disk!
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callback();
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}
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});
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});
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function getPackage(packageConfig, callback) {
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const tarballURL = packageConfig.dist.tarball;
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const outputDir = createTempPath(packageConfig.name, packageConfig.version);
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fetchMutex(tarballURL, { tarballURL, outputDir }, function(error) {
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callback(error, outputDir);
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});
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}
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module.exports = getPackage;
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