unpkg/server/middleware/utils/getPackage.js

89 lines
2.5 KiB
JavaScript

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