Sanitize the path to the user config before importing

[ionut-botizan]

Related to #29971

The issue with the dynamic import() is not Windows specific and the current fix is not (entirely) correct, as the import() will still fail in some cases.
The real issue is that import() expects a url-encoded string as parameter and, on Windows, the colon (:) makes it think that it's a fully qualified URL using a protocol that it doesn't recognize. But that's just part of the story...
The other part, which is true for all the POSIX compliant operating systems, is that it will try to decode any url-encoded entities, so, basically, when it encounters a % it will try to interpret the following characters as a hex code. So, for example, if it encounters a file path like /foo%20bar/baz.js, it will interpret it as /foo bar/baz.js, because %20 is the url-encoded <space> character.

The solution for this is to use the url.pathToFileURL() method to properly handle the path, like so:

import { pathToFileURL } from 'url'
// ...
userConfigModule = await import(pathToFileURL(path).href)

This will properly encode the % sign and add the necessary prefix and, given the above example, will generate a url like file:///foo%2520bar/baz.js (where %25 is the url-encoded representation of the % character).

---

To test this behavior yourself, create the following 2 files:

// ./import%20me.js

module.exports = { "answer": 42 }

// ./main.js

const url = require('url')
const path = require('path')

const absoluteFilePath = path.join(__dirname, 'import%20me.js')
const prefixedFilePath = `file://${absoluteFilePath}`
const escapedFilePath = url.pathToFileURL(absoluteFilePath)

loadFile('ESCAPED', escapedFilePath)
loadFile('PREFIXED', prefixedFilePath)

async function loadFile(method, fullPath) {
	import(fullPath)
		.then(data => console.log(`\nThe ${method} method loaded:\n\t`, data.default))
		.catch(err => console.log(`\nThe ${method} method failed with error:\n\t`, err.message))
}

...and run node main.js.

The output should be something like

The PREFIXED method failed with error:
         Cannot find module 'D:\Playground\path-to-file-url\import me.js' imported from D:\Playground\path-to-file-url\main.js

The ESCAPED method loaded:
         { answer: 42 }

Bug

• Related issues linked using fixes #number
• Integration tests added
• Errors have helpful link attached, see contributing.md

Feature

• Implements an existing feature request or RFC. Make sure the feature request has been accepted for implementation before opening a PR.
• Related issues linked using fixes #number
• Integration tests added
• Documentation added
• Telemetry added. In case of a feature if it's used or not.
• Errors have helpful link attached, see contributing.md

Documentation / Examples

• Make sure the linting passes

[ijjk]

Stats from current PR

Default Build (Decrease detected ✓)

General Overall increase ⚠️

	vercel/next.js canary	ionut-botizan/next.js bugfix/user-config-import	Change
buildDuration	15.6s	15.5s	-48ms
buildDurationCached	3.6s	3.5s	-44ms
nodeModulesSize	195 MB	195 MB	⚠️ +300 B

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	ionut-botizan/next.js bugfix/user-config-import	Change
/ failed reqs	0	0	✓
/ total time (seconds)	3.633	3.787	⚠️ +0.15
/ avg req/sec	688.15	660.16	⚠️ -27.99
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.909	1.899	-0.01
/error-in-render avg req/sec	1309.49	1316.65	+7.16

Client Bundles (main, webpack, commons)

	vercel/next.js canary	ionut-botizan/next.js bugfix/user-config-import	Change
558.HASH.js gzip	3.02 kB	3.02 kB	✓
779.HASH.js gzip	179 B	179 B	✓
framework-HASH.js gzip	42.2 kB	42.2 kB	✓
main-HASH.js gzip	25 kB	25 kB	✓
webpack-HASH.js gzip	1.49 kB	1.49 kB	✓
Overall change	71.9 kB	71.9 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	ionut-botizan/next.js bugfix/user-config-import	Change
polyfills-a4..dd70.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	ionut-botizan/next.js bugfix/user-config-import	Change
_app-HASH.js gzip	977 B	977 B	✓
_error-HASH.js gzip	3.11 kB	3.11 kB	✓
amp-HASH.js gzip	553 B	553 B	✓
css-HASH.js gzip	328 B	328 B	✓
dynamic-HASH.js gzip	2.73 kB	2.73 kB	✓
head-HASH.js gzip	2.37 kB	2.37 kB	✓
hooks-HASH.js gzip	918 B	918 B	✓
image-HASH.js gzip	5.85 kB	5.85 kB	✓
index-HASH.js gzip	260 B	260 B	✓
link-HASH.js gzip	1.66 kB	1.66 kB	✓
routerDirect..HASH.js gzip	320 B	320 B	✓
script-HASH.js gzip	386 B	386 B	✓
withRouter-HASH.js gzip	319 B	319 B	✓
bb14e60e810b..30f.css gzip	125 B	125 B	✓
Overall change	19.9 kB	19.9 kB	✓

Client Build Manifests

	vercel/next.js canary	ionut-botizan/next.js bugfix/user-config-import	Change
_buildManifest.js gzip	493 B	493 B	✓
Overall change	493 B	493 B	✓

Rendered Page Sizes

	vercel/next.js canary	ionut-botizan/next.js bugfix/user-config-import	Change
index.html gzip	539 B	539 B	✓
link.html gzip	550 B	550 B	✓
withRouter.html gzip	532 B	532 B	✓
Overall change	1.62 kB	1.62 kB	✓

---

Default Build with SWC (Decrease detected ✓)

General Overall increase ⚠️

	vercel/next.js canary	ionut-botizan/next.js bugfix/user-config-import	Change
buildDuration	7.7s	7.6s	-32ms
buildDurationCached	3.9s	3.7s	-208ms
nodeModulesSize	195 MB	195 MB	⚠️ +300 B

Page Load Tests Overall decrease ⚠️

	vercel/next.js canary	ionut-botizan/next.js bugfix/user-config-import	Change
/ failed reqs	0	0	✓
/ total time (seconds)	3.659	3.712	⚠️ +0.05
/ avg req/sec	683.18	673.46	⚠️ -9.72
/error-in-render failed reqs	0	0	✓
/error-in-render total time (seconds)	1.842	1.895	⚠️ +0.05
/error-in-render avg req/sec	1357.05	1319.39	⚠️ -37.66

Client Bundles (main, webpack, commons)

	vercel/next.js canary	ionut-botizan/next.js bugfix/user-config-import	Change
675-HASH.js gzip	13.8 kB	13.8 kB	✓
770.HASH.js gzip	178 B	178 B	✓
framework-HASH.js gzip	50.8 kB	50.8 kB	✓
main-HASH.js gzip	35.2 kB	35.2 kB	✓
webpack-HASH.js gzip	1.64 kB	1.64 kB	✓
Overall change	102 kB	102 kB	✓

Legacy Client Bundles (polyfills)

	vercel/next.js canary	ionut-botizan/next.js bugfix/user-config-import	Change
polyfills-a4..dd70.js gzip	31 kB	31 kB	✓
Overall change	31 kB	31 kB	✓

Client Pages

	vercel/next.js canary	ionut-botizan/next.js bugfix/user-config-import	Change
_app-HASH.js gzip	1.33 kB	1.33 kB	✓
_error-HASH.js gzip	180 B	180 B	✓
amp-HASH.js gzip	315 B	315 B	✓
css-HASH.js gzip	331 B	331 B	✓
dynamic-HASH.js gzip	2.79 kB	2.79 kB	✓
head-HASH.js gzip	355 B	355 B	✓
hooks-HASH.js gzip	637 B	637 B	✓
image-HASH.js gzip	555 B	555 B	✓
index-HASH.js gzip	261 B	261 B	✓
link-HASH.js gzip	2.22 kB	2.22 kB	✓
routerDirect..HASH.js gzip	326 B	326 B	✓
script-HASH.js gzip	393 B	393 B	✓
withRouter-HASH.js gzip	322 B	322 B	✓
bb14e60e810b..30f.css gzip	125 B	125 B	✓
Overall change	10.1 kB	10.1 kB	✓

Client Build Manifests

	vercel/next.js canary	ionut-botizan/next.js bugfix/user-config-import	Change
_buildManifest.js gzip	511 B	511 B	✓
Overall change	511 B	511 B	✓

Rendered Page Sizes

	vercel/next.js canary	ionut-botizan/next.js bugfix/user-config-import	Change
index.html gzip	539 B	539 B	✓
link.html gzip	552 B	552 B	✓
withRouter.html gzip	533 B	533 B	✓
Overall change	1.62 kB	1.62 kB	✓

Commit: 3526055

[ijjk]

Thanks for the PR!