89 lines
2.5 KiB
JavaScript
89 lines
2.5 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 ignoreSymlinks(file, headers) {
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return headers.type === 'link'
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}
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function extractResponse(response, outputDir) {
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return new Promise(function(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: ignoreSymlinks
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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(function(response) {
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return extractResponse(response, outputDir)
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})
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}
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const fetchMutex = createMutex(function(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(function() {
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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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