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module: resolver & spec hardening /w refactoring
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@guybedford
guybedford committed Oct 24, 2021
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96 changes: 52 additions & 44 deletions doc/api/esm.md
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Original file line number Diff line number Diff line change
Expand Up @@ -1077,59 +1077,63 @@ The resolver can throw the following errors:
> 1. Note: _specifier_ is now a bare specifier.
> 2. Set _resolved_ the result of
> **PACKAGE\_RESOLVE**(_specifier_, _parentURL_).
> 6. If _resolved_ contains any percent encodings of _"/"_ or _"\\"_ (_"%2f"_
> and _"%5C"_ respectively), then
> 1. Throw an _Invalid Module Specifier_ error.
> 7. If the file at _resolved_ is a directory, then
> 1. Throw an _Unsupported Directory Import_ error.
> 8. If the file at _resolved_ does not exist, then
> 1. Throw a _Module Not Found_ error.
> 9. Set _resolved_ to the real path of _resolved_.
> 10. Let _format_ be the result of **ESM\_FORMAT**(_resolved_).
> 11. Load _resolved_ as module format, _format_.
> 12. Return _resolved_.
> 6. Let _format_ be **undefined**.
> 7. If _resolved_ is a _"file:"_ URL, then
> 1. If _resolved_ contains any percent encodings of _"/"_ or _"\\"_ (_"%2F"_
> and _"%5C"_ respectively), then
> 1. Throw an _Invalid Module Specifier_ error.
> 2. If the file at _resolved_ is a directory, then
> 1. Throw an _Unsupported Directory Import_ error.
> 3. If the file at _resolved_ does not exist, then
> 1. Throw a _Module Not Found_ error.
> 4. Set _resolved_ to the real path of _resolved_, maintaining the
> same URL querystring and fragment components.
> 5. Set _format_ to the result of **ESM\_FILE\_FORMAT**(_resolved_).
> 8. Otherwise,
> 1. Set _format_ the module format of the content type associated with the
> URL _resolved_.
> 9. Load _resolved_ as module format, _format_.

**PACKAGE\_RESOLVE**(_packageSpecifier_, _parentURL_)

> 1. Let _packageName_ be **undefined**.
> 2. If _packageSpecifier_ is an empty string, then
> 1. Throw an _Invalid Module Specifier_ error.
> 3. If _packageSpecifier_ does not start with _"@"_, then
> 3. If _packageSpecifier_ is a Node.js builtin module name, then
> 1. Return the string _"node:"_ concatenated with _packageSpecifier_.
> 4. If _packageSpecifier_ does not start with _"@"_, then
> 1. Set _packageName_ to the substring of _packageSpecifier_ until the first
> _"/"_ separator or the end of the string.
> 4. Otherwise,
> 5. Otherwise,
> 1. If _packageSpecifier_ does not contain a _"/"_ separator, then
> 1. Throw an _Invalid Module Specifier_ error.
> 2. Set _packageName_ to the substring of _packageSpecifier_
> until the second _"/"_ separator or the end of the string.
> 5. If _packageName_ starts with _"."_ or contains _"\\"_ or _"%"_, then
> 6. If _packageName_ starts with _"."_ or contains _"\\"_ or _"%"_, then
> 1. Throw an _Invalid Module Specifier_ error.
> 6. Let _packageSubpath_ be _"."_ concatenated with the substring of
> 7. Let _packageSubpath_ be _"."_ concatenated with the substring of
> _packageSpecifier_ from the position at the length of _packageName_.
> 7. If _packageSubpath_ ends in _"/"_, then
> 8. If _packageSubpath_ ends in _"/"_, then
> 1. Throw an _Invalid Module Specifier_ error.
> 8. Let _selfUrl_ be the result of
> 9. Let _selfUrl_ be the result of
> **PACKAGE\_SELF\_RESOLVE**(_packageName_, _packageSubpath_, _parentURL_).
> 9. If _selfUrl_ is not **undefined**, return _selfUrl_.
> 10. If _packageSubpath_ is _"."_ and _packageName_ is a Node.js builtin
> module, then
> 1. Return the string _"node:"_ concatenated with _packageSpecifier_.
> 10. If _selfUrl_ is not **undefined**, return _selfUrl_.
> 11. While _parentURL_ is not the file system root,
> 1. Let _packageURL_ be the URL resolution of _"node\_modules/"_
> concatenated with _packageSpecifier_, relative to _parentURL_.
> 2. Set _parentURL_ to the parent folder URL of _parentURL_.
> 3. If the folder at _packageURL_ does not exist, then
> 1. Continue the next loop iteration.
> 4. Let _pjson_ be the result of **READ\_PACKAGE\_JSON**(_packageURL_).
> 5. If _pjson_ is not **null** and _pjson_._exports_ is not **null** or
> **undefined**, then
> 1. Return the result of **PACKAGE\_EXPORTS\_RESOLVE**(_packageURL_,
> _packageSubpath_, _pjson.exports_, _defaultConditions_).
> 6. Otherwise, if _packageSubpath_ is equal to _"."_, then
> 1. If _pjson.main_ is a string, then
> 1. Return the URL resolution of _main_ in _packageURL_.
> 7. Otherwise,
> 1. Return the URL resolution of _packageSubpath_ in _packageURL_.
> 1. Let _packageURL_ be the URL resolution of _"node_modules/"_
> concatenated with _packageSpecifier_, relative to _parentURL_.
> 2. Set _parentURL_ to the parent folder URL of _parentURL_.
> 3. If the folder at _packageURL_ does not exist, then
> 1. Continue the next loop iteration.
> 4. Let _pjson_ be the result of **READ\_PACKAGE\_JSON**(_packageURL_).
> 5. If _pjson_ is not **null** and _pjson_._exports_ is not **null** or
> **undefined**, then
> 1. Return the result of **PACKAGE\_EXPORTS\_RESOLVE**(_packageURL_,
> _packageSubpath_, _pjson.exports_, _defaultConditions_).
> 6. Otherwise, if _packageSubpath_ is equal to _"."_, then
> 1. If _pjson.main_ is a string, then
> 1. Return the URL resolution of _main_ in _packageURL_.
> 7. Otherwise,
> 1. Return the URL resolution of _packageSubpath_ in _packageURL_.
> 12. Throw a _Module Not Found_ error.

**PACKAGE\_SELF\_RESOLVE**(_packageName_, _packageSubpath_, _parentURL_)
Expand Down Expand Up @@ -1239,18 +1243,20 @@ _internal_, _conditions_)
> _"/"_ and is not a valid URL, then
> 1. If _pattern_ is **true**, then
> 1. Return **PACKAGE\_RESOLVE**(_target_ with every instance of
> _"\*"_ replaced by _subpath_, _packageURL_ + _"/"_)\_.
> _"\*"_ replaced by _subpath_, _packageURL_ + _"/"_).
> 2. Return **PACKAGE\_RESOLVE**(_target_ + _subpath_,
> _packageURL_ + _"/"_)\_.
> _packageURL_ + _"/"_)_.
> 2. Otherwise, throw an _Invalid Package Target_ error.
> 3. If _target_ split on _"/"_ or _"\\"_ contains any _"."_, _".."_ or
> _"node\_modules"_ segments after the first segment, throw an
> _Invalid Package Target_ error.
> _"node\_modules"_ segments after the first segment, case insensitive and
> including percent encoded variants, throw an _Invalid Package Target_
> error.
> 4. Let _resolvedTarget_ be the URL resolution of the concatenation of
> _packageURL_ and _target_.
> 5. Assert: _resolvedTarget_ is contained in _packageURL_.
> 6. If _subpath_ split on _"/"_ or _"\\"_ contains any _"."_, _".."_ or
> _"node\_modules"_ segments, throw an _Invalid Module Specifier_ error.
> _"node\_modules"_ segments, case insensitive and including percent
> encoded variants, throw an _Invalid Module Specifier_ error.
> 7. If _pattern_ is **true**, then
> 1. Return the URL resolution of _resolvedTarget_ with every instance of
> _"\*"_ replaced with _subpath_.
Expand Down Expand Up @@ -1283,19 +1289,21 @@ _internal_, _conditions_)
> 4. Otherwise, if _target_ is _null_, return **null**.
> 5. Otherwise throw an _Invalid Package Target_ error.

**ESM\_FORMAT**(_url_)
**ESM\_FILE\_FORMAT**(_url_)

> 1. Assert: _url_ corresponds to an existing file.
> 2. Let _pjson_ be the result of **READ\_PACKAGE\_SCOPE**(_url_).
> 3. If _url_ ends in _".mjs"_, then
> 1. Return _"module"_.
> 4. If _url_ ends in _".cjs"_, then
> 1. Return _"commonjs"_.
> 5. If _pjson?.type_ exists and is _"module"_, then
> 5. If _url_ ends in _".json"_, then
> 1. Return _"json"_.
> 6. If _pjson?.type_ exists and is _"module"_, then
> 1. If _url_ ends in _".js"_, then
> 1. Return _"module"_.
> 2. Throw an _Unsupported File Extension_ error.
> 6. Otherwise,
> 7. Otherwise,
> 1. Throw an _Unsupported File Extension_ error.

**READ\_PACKAGE\_SCOPE**(_url_)
Expand Down
77 changes: 32 additions & 45 deletions lib/internal/modules/esm/resolve.js
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Original file line number Diff line number Diff line change
Expand Up @@ -10,6 +10,7 @@ const {
ObjectGetOwnPropertyNames,
ObjectPrototypeHasOwnProperty,
RegExp,
RegExpPrototypeExec,
RegExpPrototypeSymbolReplace,
RegExpPrototypeTest,
SafeMap,
Expand Down Expand Up @@ -360,9 +361,10 @@ const encodedSepRegEx = /%2F|%5C/i;
/**
* @param {URL} resolved
* @param {string | URL | undefined} base
* @param {boolean} preserveSymlinks
* @returns {URL | undefined}
*/
function finalizeResolution(resolved, base) {
function finalizeResolution(resolved, base, preserveSymlinks) {
if (RegExpPrototypeTest(encodedSepRegEx, resolved.pathname))
throw new ERR_INVALID_MODULE_SPECIFIER(
resolved.pathname, 'must not include encoded "/" or "\\" characters',
Expand Down Expand Up @@ -393,6 +395,17 @@ function finalizeResolution(resolved, base) {
path || resolved.pathname, base && fileURLToPath(base), 'module');
}

if (!preserveSymlinks) {
const real = realpathSync(path, {
[internalFS.realpathCacheKey]: realpathCache
});
const { search, hash } = resolved;
resolved =
pathToFileURL(real + (StringPrototypeEndsWith(path, sep) ? '/' : ''));
resolved.search = search;
resolved.hash = hash;
}

return resolved;
}

Expand Down Expand Up @@ -444,7 +457,8 @@ function throwInvalidPackageTarget(
internal, base && fileURLToPath(base));
}

const invalidSegmentRegEx = /(^|\\|\/)(\.\.?|node_modules)(\\|\/|$)/;
const invalidSegmentRegEx = /(^|\\|\/)((\.|%2e)(\.|%2e)?|(n|%6e|%4e)(o|%6f|%4f)(d|%64|%44)(e|%65|%45)(_|%5f)(m|%6d|%4d)(o|%6f|%4f)(d|%64|%44)(u|%75|%55)(l|%6c|%4c)(e|%65|%45)(s|%73|%53))(\\|\/|$)/i;
const invalidPackageNameRegEx = /^\.|%|\\/;
const patternRegEx = /\*/g;

function resolvePackageTargetString(
Expand Down Expand Up @@ -777,13 +791,9 @@ function parsePackageName(specifier, base) {
specifier : StringPrototypeSlice(specifier, 0, separatorIndex);

// Package name cannot have leading . and cannot have percent-encoding or
// separators.
for (let i = 0; i < packageName.length; i++) {
if (packageName[i] === '%' || packageName[i] === '\\') {
validPackageName = false;
break;
}
}
// \\ separators.
if (RegExpPrototypeExec(invalidPackageNameRegEx, packageName) !== null)
validPackageName = false;

if (!validPackageName) {
throw new ERR_INVALID_MODULE_SPECIFIER(
Expand All @@ -803,6 +813,9 @@ function parsePackageName(specifier, base) {
* @returns {URL}
*/
function packageResolve(specifier, base, conditions) {
if (NativeModule.canBeRequiredByUsers(specifier))
return new URL('node:' + specifier);

const { packageName, packageSubpath, isScoped } =
parsePackageName(specifier, base);

Expand Down Expand Up @@ -879,9 +892,10 @@ function shouldBeTreatedAsRelativeOrAbsolutePath(specifier) {
* @param {string} specifier
* @param {string | URL | undefined} base
* @param {Set<string>} conditions
* @param {boolean} preserveSymlinks
* @returns {URL}
*/
function moduleResolve(specifier, base, conditions) {
function moduleResolve(specifier, base, conditions, preserveSymlinks) {
// Order swapped from spec for minor perf gain.
// Ok since relative URLs cannot parse as URLs.
let resolved;
Expand All @@ -896,7 +910,9 @@ function moduleResolve(specifier, base, conditions) {
resolved = packageResolve(specifier, base, conditions);
}
}
return finalizeResolution(resolved, base);
if (resolved.protocol !== 'file:')
return resolved;
return finalizeResolution(resolved, base, preserveSymlinks);
}

/**
Expand Down Expand Up @@ -968,28 +984,6 @@ function defaultResolve(specifier, context = {}, defaultResolveUnused) {
}
}
}
let parsed;
try {
parsed = new URL(specifier);
if (parsed.protocol === 'data:') {
return {
url: specifier
};
}
} catch {}
if (parsed && parsed.protocol === 'node:')
return { url: specifier };
if (parsed && parsed.protocol !== 'file:' && parsed.protocol !== 'data:')
throw new ERR_UNSUPPORTED_ESM_URL_SCHEME(parsed);
if (NativeModule.canBeRequiredByUsers(specifier)) {
return {
url: 'node:' + specifier
};
}
if (parentURL && StringPrototypeStartsWith(parentURL, 'data:')) {
// This is gonna blow up, we want the error
new URL(specifier, parentURL);
}

const isMain = parentURL === undefined;
if (isMain) {
Expand All @@ -1008,7 +1002,8 @@ function defaultResolve(specifier, context = {}, defaultResolveUnused) {
conditions = getConditionsSet(conditions);
let url;
try {
url = moduleResolve(specifier, parentURL, conditions);
url = moduleResolve(specifier, parentURL, conditions,
isMain ? preserveSymlinksMain : preserveSymlinks);
} catch (error) {
// Try to give the user a hint of what would have been the
// resolved CommonJS module
Expand All @@ -1032,17 +1027,9 @@ function defaultResolve(specifier, context = {}, defaultResolveUnused) {
throw error;
}

if (isMain ? !preserveSymlinksMain : !preserveSymlinks) {
const urlPath = fileURLToPath(url);
const real = realpathSync(urlPath, {
[internalFS.realpathCacheKey]: realpathCache
});
const old = url;
url = pathToFileURL(
real + (StringPrototypeEndsWith(urlPath, sep) ? '/' : ''));
url.search = old.search;
url.hash = old.hash;
}
if (url.protocol !== 'file:' && url.protocol !== 'data:' &&
url.protocol !== 'node:')
throw new ERR_UNSUPPORTED_ESM_URL_SCHEME(url);

return { url: `${url}` };
}
Expand Down
4 changes: 4 additions & 0 deletions test/es-module/test-esm-exports.mjs
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Original file line number Diff line number Diff line change
Expand Up @@ -104,6 +104,10 @@ import fromInside from '../fixtures/node_modules/pkgexports/lib/hole.js';
// Even though 'pkgexports/sub/asdf.js' works, alternate "path-like"
// variants do not to prevent confusion and accidental loopholes.
['pkgexports/sub/./../asdf.js', './sub/./../asdf.js'],
// Cannot reach into node_modules, even percent encoded
['pkgexports/sub/no%64e_modules', './sub/no%64e_modules'],
// Cannot backtrack below exposed path, even with percent encoded "."
['pkgexports/sub/%2e./asdf', './asdf'],
]);

for (const [specifier, subpath] of undefinedExports) {
Expand Down

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