module: add findPackageJSON util

doc/api/module.md

@@ -217,6 +217,88 @@ added: v22.8.0
 * Returns: {string|undefined} Path to the [module compile cache][] directory if it is enabled,
   or `undefined` otherwise.
 
+### `module.findPackageJSON(specifier[, base])`
+
+<!-- YAML
+added: REPLACEME
+-->
+
+> Stability: 1.1 - Active Development
+
+* `specifier` {string|URL} The specifier for the module whose `package.json` to
+  retrieve. When passing a _bare specifier_, the `package.json` at the root of
+  the package is returned. When passing a _relative specifier_ or an _absolute specifier_,
+  the closest parent `package.json` is returned.
+* `base` {string|URL} The absolute location (`file:` URL string or FS path) of the
+  containing  module. For CJS, use `__filename` (not `__dirname`!); for ESM, use
+  `import.meta.url`. You do not need to pass it if `specifier` is an `absolute specifier`.
+* Returns: {string|undefined} A path if the `package.json` is found. When `startLocation`
+  is a package, the package's root `package.json`; when a relative or unresolved, the closest
+  `package.json` to the `startLocation`.
+
+> **Caveat**: Do not use this to try to determine module format. There are many things effecting
+> that determination; the `type` field of package.json is the _least_ definitive (ex file extension
+> superceeds it, and a loader hook superceeds that).
+
+```text
+/path/to/project
+  ├ packages/
+    ├ bar/
+      ├ bar.js
+      └ package.json // name = '@foo/bar'
+    └ qux/
+      ├ node_modules/
+        └ some-package/
+          └ package.json // name = 'some-package'
+      ├ qux.js
+      └ package.json // name = '@foo/qux'
+  ├ main.js
+  └ package.json // name = '@foo'
+```
+
+```mjs
+// /path/to/project/packages/bar/bar.js
+import { findPackageJSON } from 'node:module';
+
+findPackageJSON('..', import.meta.url);
+// '/path/to/project/package.json'
+// Same result when passing an absolute specifier instead:
+findPackageJSON(new URL('../', import.meta.url));
+findPackageJSON(import.meta.resolve('../'));
+
+findPackageJSON('some-package', import.meta.url);
+// '/path/to/project/packages/bar/node_modules/some-package/package.json'
+// When passing an absolute specifier, you might get a different result if the
+// resolved module is inside a subfolder that has nested `package.json`.
+findPackageJSON(import.meta.resolve('some-package'));
+// '/path/to/project/packages/bar/node_modules/some-package/some-subfolder/package.json'
+
+findPackageJSON('@foo/qux', import.meta.url);
+// '/path/to/project/packages/qux/package.json'
+```
+
+```cjs
+// /path/to/project/packages/bar/bar.js
+const { findPackageJSON } = require('node:module');
+const { pathToFileURL } = require('node:url');
+const path = require('node:path');
+
+findPackageJSON('..', __filename);
+// '/path/to/project/package.json'
+// Same result when passing an absolute specifier instead:
+findPackageJSON(pathToFileURL(path.join(__dirname, '..')));
+
+findPackageJSON('some-package', __filename);
+// '/path/to/project/packages/bar/node_modules/some-package/package.json'
+// When passing an absolute specifier, you might get a different result if the
+// resolved module is inside a subfolder that has nested `package.json`.
+findPackageJSON(pathToFileURL(require.resolve('some-package')));
+// '/path/to/project/packages/bar/node_modules/some-package/some-subfolder/package.json'
+
+findPackageJSON('@foo/qux', __filename);
+// '/path/to/project/packages/qux/package.json'
+```
+
 ### `module.isBuiltin(moduleName)`
 
 <!-- YAML

lib/internal/modules/cjs/loader.js

@@ -602,11 +602,11 @@ function trySelf(parentPath, request) {
   try {
     const { packageExportsResolve } = require('internal/modules/esm/resolve');
     return finalizeEsmResolution(packageExportsResolve(
-      pathToFileURL(pkg.path + '/package.json'), expansion, pkg.data,
+      pathToFileURL(pkg.path), expansion, pkg.data,
       pathToFileURL(parentPath), getCjsConditions()), parentPath, pkg.path);
   } catch (e) {
     if (e.code === 'ERR_MODULE_NOT_FOUND') {
-      throw createEsmNotFoundErr(request, pkg.path + '/package.json');
+      throw createEsmNotFoundErr(request, pkg.path);
     }
     throw e;
   }
@@ -1201,14 +1201,15 @@ Module._resolveFilename = function(request, parent, isMain, options) {
 
   if (request[0] === '#' && (parent?.filename || parent?.id === '<repl>')) {
     const parentPath = parent?.filename ?? process.cwd() + path.sep;
-    const pkg = packageJsonReader.getNearestParentPackageJSON(parentPath) || { __proto__: null };
-    if (pkg.data?.imports != null) {
+    const pkg = packageJsonReader.getNearestParentPackageJSON(parentPath);
+    if (pkg?.data.imports != null) {
       try {
         const { packageImportsResolve } = require('internal/modules/esm/resolve');
         return finalizeEsmResolution(
-          packageImportsResolve(request, pathToFileURL(parentPath),
-                                getCjsConditions()), parentPath,
-          pkg.path);
+          packageImportsResolve(request, pathToFileURL(parentPath), getCjsConditions()),
+          parentPath,
+          pkg.path,
+        );
       } catch (e) {
         if (e.code === 'ERR_MODULE_NOT_FOUND') {
           throw createEsmNotFoundErr(request);
@@ -1268,8 +1269,7 @@ function finalizeEsmResolution(resolved, parentPath, pkgPath) {
   if (actual) {
     return actual;
   }
-  const err = createEsmNotFoundErr(filename,
-                                   path.resolve(pkgPath, 'package.json'));
+  const err = createEsmNotFoundErr(filename, pkgPath);
   throw err;
 }
 
@@ -1623,7 +1623,7 @@ function loadTS(module, filename) {
 
     const parent = module[kModuleParent];
     const parentPath = parent?.filename;
-    const packageJsonPath = path.resolve(pkg.path, 'package.json');
+    const packageJsonPath = pkg.path;
     const usesEsm = containsModuleSyntax(content, filename);
     const err = new ERR_REQUIRE_ESM(filename, usesEsm, parentPath,
                                     packageJsonPath);
@@ -1682,7 +1682,7 @@ Module._extensions['.js'] = function(module, filename) {
       // This is an error path because `require` of a `.js` file in a `"type": "module"` scope is not allowed.
       const parent = module[kModuleParent];
       const parentPath = parent?.filename;
-      const packageJsonPath = path.resolve(pkg.path, 'package.json');
+      const packageJsonPath = pkg.path;
       const usesEsm = containsModuleSyntax(content, filename);
       const err = new ERR_REQUIRE_ESM(filename, usesEsm, parentPath,
                                       packageJsonPath);

lib/internal/modules/esm/resolve.js

@@ -356,7 +356,6 @@ function invalidPackageTarget(
 
 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))?(\\|\/|$)/i;
 const deprecatedInvalidSegmentRegEx = /(^|\\|\/)((\.|%2e)(\.|%2e)?|(n|%6e|%4e)(o|%6f|%4f)(d|%64|%44)(e|%65|%45)(_|%5f)(m|%6d|%4d)(o|%6f|%4f)(d|%64|%44)(u|%75|%55)(l|%6c|%4c)(e|%65|%45)(s|%73|%53))(\\|\/|$)/i;
-const invalidPackageNameRegEx = /^\.|%|\\/;
 const patternRegEx = /\*/g;
 
 /**
@@ -752,44 +751,6 @@ function packageImportsResolve(name, base, conditions) {
   throw importNotDefined(name, packageJSONUrl, base);
 }
 
-/**
- * Parse a package name from a specifier.
- * @param {string} specifier - The import specifier.
- * @param {string | URL | undefined} base - The parent URL.
- */
-function parsePackageName(specifier, base) {
-  let separatorIndex = StringPrototypeIndexOf(specifier, '/');
-  let validPackageName = true;
-  let isScoped = false;
-  if (specifier[0] === '@') {
-    isScoped = true;
-    if (separatorIndex === -1 || specifier.length === 0) {
-      validPackageName = false;
-    } else {
-      separatorIndex = StringPrototypeIndexOf(
-        specifier, '/', separatorIndex + 1);
-    }
-  }
-
-  const packageName = separatorIndex === -1 ?
-    specifier : StringPrototypeSlice(specifier, 0, separatorIndex);
-
-  // Package name cannot have leading . and cannot have percent-encoding or
-  // \\ separators.
-  if (RegExpPrototypeExec(invalidPackageNameRegEx, packageName) !== null) {
-    validPackageName = false;
-  }
-
-  if (!validPackageName) {
-    throw new ERR_INVALID_MODULE_SPECIFIER(
-      specifier, 'is not a valid package name', fileURLToPath(base));
-  }
-
-  const packageSubpath = '.' + (separatorIndex === -1 ? '' :
-    StringPrototypeSlice(specifier, separatorIndex));
-
-  return { packageName, packageSubpath, isScoped };
-}
 
 /**
  * Resolves a package specifier to a URL.
@@ -804,57 +765,24 @@ function packageResolve(specifier, base, conditions) {
     return new URL('node:' + specifier);
   }
 
-  const { packageName, packageSubpath, isScoped } =
-    parsePackageName(specifier, base);
+  const { packageJSONUrl, packageJSONPath, packageSubpath } = packageJsonReader.getPackageJSONURL(specifier, base);
 
-  // ResolveSelf
-  const packageConfig = packageJsonReader.getPackageScopeConfig(base);
-  if (packageConfig.exists) {
-    if (packageConfig.exports != null && packageConfig.name === packageName) {
-      const packageJSONUrl = pathToFileURL(packageConfig.pjsonPath);
-      return packageExportsResolve(
-        packageJSONUrl, packageSubpath, packageConfig, base, conditions);
-    }
-  }
+  const packageConfig = packageJsonReader.read(packageJSONPath, { __proto__: null, specifier, base, isESM: true });
 
-  let packageJSONUrl =
-    new URL('./node_modules/' + packageName + '/package.json', base);
-  let packageJSONPath = fileURLToPath(packageJSONUrl);
-  let lastPath;
-  do {
-    const stat = internalFsBinding.internalModuleStat(
-      internalFsBinding,
-      StringPrototypeSlice(packageJSONPath, 0, packageJSONPath.length - 13),
+  // Package match.
+  if (packageConfig.exports != null) {
+    return packageExportsResolve(
+      packageJSONUrl, packageSubpath, packageConfig, base, conditions);
+  }
+  if (packageSubpath === '.') {
+    return legacyMainResolve(
+      packageJSONUrl,
+      packageConfig,
+      base,
     );
-    // Check for !stat.isDirectory()
-    if (stat !== 1) {
-      lastPath = packageJSONPath;
-      packageJSONUrl = new URL((isScoped ?
-        '../../../../node_modules/' : '../../../node_modules/') +
-        packageName + '/package.json', packageJSONUrl);
-      packageJSONPath = fileURLToPath(packageJSONUrl);
-      continue;
-    }
-
-    // Package match.
-    const packageConfig = packageJsonReader.read(packageJSONPath, { __proto__: null, specifier, base, isESM: true });
-    if (packageConfig.exports != null) {
-      return packageExportsResolve(
-        packageJSONUrl, packageSubpath, packageConfig, base, conditions);
-    }
-    if (packageSubpath === '.') {
-      return legacyMainResolve(
-        packageJSONUrl,
-        packageConfig,
-        base,
-      );
-    }
-
-    return new URL(packageSubpath, packageJSONUrl);
-    // Cross-platform root check.
-  } while (packageJSONPath.length !== lastPath.length);
+  }
 
-  throw new ERR_MODULE_NOT_FOUND(packageName, fileURLToPath(base), null);
+  return new URL(packageSubpath, packageJSONUrl);
 }
 
 /**
@@ -1105,10 +1033,11 @@ module.exports = {
   decorateErrorWithCommonJSHints,
   defaultResolve,
   encodedSepRegEx,
+  legacyMainResolve,
   packageExportsResolve,
   packageImportsResolve,
+  packageResolve,
   throwIfInvalidParentURL,
-  legacyMainResolve,
 };
 
 // cycle