fs: introduce dirent.parentPath

The goal is to replace `dirent.path` using a name that's less likely to
create confusion.
`dirent.path` value has not been stable, moving it to a different
property name should avoid breaking some upgrading user expectations.

PR-URL: #50976
Backport-PR-URL: #51021
Reviewed-By: Ethan Arrowood <ethan@arrowood.dev>
Reviewed-By: LiviaMedeiros <livia@cirno.name>

doc/api/fs.md

@@ -6437,6 +6437,19 @@ The file name that this {fs.Dirent} object refers to. The type of this
 value is determined by the `options.encoding` passed to [`fs.readdir()`][] or
 [`fs.readdirSync()`][].
 
+#### `dirent.parentPath`
+
+<!-- YAML
+added:
+  - REPLACEME
+-->
+
+> Stability: 1 – Experimental
+
+* {string}
+
+The path to the parent directory of the file this {fs.Dirent} object refers to.
+
 #### `dirent.path`
 
 <!-- YAML

lib/internal/fs/dir.js

@@ -152,9 +152,10 @@ class Dir {
       ArrayPrototypePush(
         this[kDirBufferedEntries],
         getDirent(
-          pathModule.join(path, result[i]),
+          path,
           result[i],
           result[i + 1],
+          true, // Quirk to not introduce a breaking change.
         ),
       );
     }

lib/internal/fs/utils.js

@@ -161,9 +161,10 @@ function assertEncoding(encoding) {
 }
 
 class Dirent {
-  constructor(name, type, path) {
+  constructor(name, type, path, filepath = path && join(path, name)) {
     this.name = name;
-    this.path = path;
+    this.parentPath = path;
+    this.path = filepath;
     this[kType] = type;
   }
 
@@ -197,8 +198,8 @@ class Dirent {
 }
 
 class DirentFromStats extends Dirent {
-  constructor(name, stats, path) {
-    super(name, null, path);
+  constructor(name, stats, path, filepath) {
+    super(name, null, path, filepath);
     this[kStats] = stats;
   }
 }
@@ -233,7 +234,7 @@ function join(path, name) {
   }
 
   if (typeof path === 'string' && typeof name === 'string') {
-    return pathModule.basename(path) === name ? path : pathModule.join(path, name);
+    return pathModule.join(path, name);
   }
 
   if (isUint8Array(path) && isUint8Array(name)) {
@@ -268,7 +269,7 @@ function getDirents(path, { 0: names, 1: types }, callback) {
             callback(err);
             return;
           }
-          names[idx] = new DirentFromStats(name, stats, path);
+          names[idx] = new DirentFromStats(name, stats, path, filepath);
           if (--toFinish === 0) {
             callback(null, names);
           }
@@ -304,17 +305,21 @@ function getDirent(path, name, type, callback) {
           callback(err);
           return;
         }
-        callback(null, new DirentFromStats(name, stats, filepath));
+        callback(null, new DirentFromStats(name, stats, path, filepath));
       });
     } else {
       callback(null, new Dirent(name, type, path));
     }
   } else if (type === UV_DIRENT_UNKNOWN) {
     const filepath = join(path, name);
     const stats = lazyLoadFs().lstatSync(filepath);
-    return new DirentFromStats(name, stats, path);
-  } else {
+    // callback === true: Quirk to not introduce a breaking change.
+    return new DirentFromStats(name, stats, path, callback === true ? filepath : path);
+  } else if (callback === true) {
+    // callback === true: Quirk to not introduce a breaking change.
     return new Dirent(name, type, path);
+  } else {
+    return new Dirent(name, type, path, path);
   }
 }
 

test/parallel/test-fs-opendir.js

@@ -48,9 +48,11 @@ const invalidCallbackObj = {
   const entries = files.map(() => {
     const dirent = dir.readSync();
     assertDirent(dirent);
-    return dirent.name;
-  });
-  assert.deepStrictEqual(files, entries.sort());
+    return { name: dirent.name, path: dirent.path, parentPath: dirent.parentPath, toString() { return dirent.name; } };
+  }).sort();
+  assert.deepStrictEqual(entries.map((d) => d.name), files);
+  assert.deepStrictEqual(entries.map((d) => d.path), files.map((name) => path.join(testDir, name)));
+  assert.deepStrictEqual(entries.map((d) => d.parentPath), Array(entries.length).fill(testDir));
 
   // dir.read should return null when no more entries exist
   assert.strictEqual(dir.readSync(), null);