unpkg/server/middleware/findFile.js

156 lines
4.5 KiB
JavaScript

const fs = require("fs");
const path = require("path");
const createPackageURL = require("../utils/createPackageURL");
const createSearch = require("./utils/createSearch");
const incrementCounter = require("./utils/incrementCounter");
/**
* File extensions to look for when automatically resolving.
*/
const resolveExtensions = ["", ".js", ".json"];
/**
* Resolves a path like "lib/file" into "lib/file.js" or "lib/file.json"
* depending on which one is available, similar to require('lib/file').
*/
function resolveFile(base, useIndex, callback) {
resolveExtensions.reduceRight((next, ext) => {
const file = base + ext;
return () => {
fs.stat(file, (error, stats) => {
if (error) {
if (error.code === "ENOENT" || error.code === "ENOTDIR") {
next();
} else {
callback(error);
}
} else if (useIndex && stats.isDirectory()) {
resolveFile(
path.join(file, "index"),
false,
(error, indexFile, indexStats) => {
if (error) {
callback(error);
} else if (indexFile) {
callback(null, indexFile, indexStats);
} else {
next();
}
}
);
} else {
callback(null, file, stats);
}
});
};
}, callback)();
}
function getBasename(file) {
return path.basename(file, path.extname(file));
}
/**
* Find the file targeted by the request and get its stats. Redirect
* inexact paths in ?module mode so relative imports resolve correctly.
*/
function findFile(req, res, next) {
let filename = req.filename;
let useIndex = true;
if (req.query.module != null) {
// They want an ES module.
if (!filename) {
// See https://github.com/rollup/rollup/wiki/pkg.module
filename =
req.packageConfig.module || req.packageConfig["jsnext:main"] || "/";
}
} else if (filename) {
// They are requesting an explicit filename. Only try to find an
// index.js if they are NOT requesting an HTML directory listing.
useIndex = filename.charAt(filename.length - 1) !== "/";
} else if (
req.query.main &&
typeof req.packageConfig[req.query.main] === "string"
) {
// They specified a custom ?main field.
// Deprecated, see https://github.com/unpkg/unpkg/issues/63
filename = req.packageConfig[req.query.main];
// Count which packages are using this so we can warn them when we
// remove this functionality.
incrementCounter(
"package-json-custom-main",
req.packageSpec + "?main=" + req.query.main,
1
);
} else if (typeof req.packageConfig.unpkg === "string") {
// The "unpkg" field allows packages to explicitly declare the
// file to serve at the bare URL.
filename = req.packageConfig.unpkg;
} else if (typeof req.packageConfig.browser === "string") {
// Fall back to the "browser" field if declared (only support strings).
// Deprecated, see https://github.com/unpkg/unpkg/issues/63
filename = req.packageConfig.browser;
// Count which packages + versions are actually using this fallback
// so we can warn them when we deprecate this functionality.
incrementCounter("package-json-browser-fallback", req.packageSpec, 1);
} else {
// Fall back to "main" or / (same as npm).
filename = req.packageConfig.main || "/";
}
resolveFile(
path.join(req.packageDir, filename),
useIndex,
(error, file, stats) => {
if (error) console.error(error);
if (file == null) {
return res
.status(404)
.type("text")
.send(
`Cannot find module "${filename}" in package ${req.packageSpec}`
);
}
filename = file.replace(req.packageDir, "");
if (
req.query.main != null ||
getBasename(req.filename) !== getBasename(filename)
) {
// Need to redirect to the module file so relative imports resolve
// correctly.
delete req.query.main;
// Cache module redirects for 1 minute.
res
.set({
"Cache-Control": "public, max-age=60",
"Cache-Tag": "redirect,module-redirect"
})
.redirect(
302,
createPackageURL(
req.packageName,
req.packageVersion,
filename,
createSearch(req.query)
)
);
} else {
req.filename = filename;
req.stats = stats;
next();
}
}
);
}
module.exports = findFile;