fs: preserve directory timestamps in cp

This fixes an issue where fs.cp and fs.cpSync (when a filter is
provided) correctly restore mtime and atime on copied files when
preserveTimestamps: true is passed, but skip restoring them for
directories.

The fix applies the existing setDestTimestamps helper to directories,
ensuring it is called after directory creation/copying but before any
modes are restored (since restoring a read-only mode would prevent
timestamp modification).

Note: This fix covers fs.cp() (async, all cases) and fs.cpSync()
when a filter is provided. The native fast path used by cpSync()
without a filter (CpSyncCopyDir in src/node_file.cc) has the
identical gap and is left for a separate follow-up contribution, since
it requires native code changes and a different review path.

Signed-off-by: Abhinandan Kumar <abhi128618@gmail.com>
PR-URL: https://github.com/nodejs/node/pull/65540
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: LiviaMedeiros <livia@cirno.name>

lib/internal/fs/cp/cp-sync.js

@@ -179,6 +179,9 @@ function copyDir(src, dest, opts, mkDir, srcMode) {
   } finally {
     dir.closeSync();
 
+    if (opts.preserveTimestamps) {
+      setDestTimestamps(src, dest);
+    }
     if (srcMode !== undefined) {
       setDestMode(dest, srcMode);
     }

lib/internal/fs/cp/cp.js

@@ -311,12 +311,18 @@ async function onDir(srcStat, destStat, src, dest, opts) {
       code: 'EEXIST',
     });
   }
-  return copyDir(src, dest, opts);
+  await copyDir(src, dest, opts);
+  if (opts.preserveTimestamps) {
+    await setDestTimestamps(src, dest);
+  }
 }
 
 async function mkDirAndCopy(srcMode, src, dest, opts) {
   await mkdir(dest);
   await copyDir(src, dest, opts);
+  if (opts.preserveTimestamps) {
+    await setDestTimestamps(src, dest);
+  }
   return setDestMode(dest, srcMode);
 }
 

test/parallel/test-fs-cp-async-preserve-timestamps-dir.mjs

@@ -0,0 +1,43 @@
+// This tests that cp() preserves directory timestamps
+// when preserveTimestamps is true.
+import { mustCall } from '../common/index.mjs';
+import { nextdir } from '../common/fs.js';
+import assert from 'node:assert';
+import { cp, mkdirSync, writeFileSync, utimesSync, statSync } from 'node:fs';
+import { join } from 'node:path';
+import tmpdir from '../common/tmpdir.js';
+
+tmpdir.refresh();
+
+// Build a source tree with a known past timestamp on directories.
+const src = nextdir();
+mkdirSync(join(src, 'subdir'), { recursive: true });
+writeFileSync(join(src, 'subdir', 'file.txt'), 'hello');
+
+const pastDate = new Date('2020-01-01T00:00:00Z');
+utimesSync(join(src, 'subdir', 'file.txt'), pastDate, pastDate);
+utimesSync(join(src, 'subdir'), pastDate, pastDate);
+utimesSync(src, pastDate, pastDate);
+
+// Copy with preserveTimestamps.
+const dest = nextdir();
+cp(src, dest, {
+  recursive: true,
+  preserveTimestamps: true,
+}, mustCall((err) => {
+  assert.strictEqual(err, null);
+
+  // Verify file timestamps are preserved (existing behaviour).
+  const srcFileStat = statSync(join(src, 'subdir', 'file.txt'));
+  const destFileStat = statSync(join(dest, 'subdir', 'file.txt'));
+  assert.strictEqual(srcFileStat.mtime.getTime(), destFileStat.mtime.getTime());
+
+  // Verify directory timestamps are preserved (the bug fix).
+  const srcDirStat = statSync(join(src, 'subdir'));
+  const destDirStat = statSync(join(dest, 'subdir'));
+  assert.strictEqual(srcDirStat.mtime.getTime(), destDirStat.mtime.getTime());
+
+  const srcRootStat = statSync(src);
+  const destRootStat = statSync(dest);
+  assert.strictEqual(srcRootStat.mtime.getTime(), destRootStat.mtime.getTime());
+}));

test/parallel/test-fs-cp-sync-preserve-timestamps-dir.mjs

@@ -0,0 +1,42 @@
+// This tests that cpSync with a filter preserves directory timestamps
+// when preserveTimestamps is true.
+import '../common/index.mjs';
+import { nextdir } from '../common/fs.js';
+import assert from 'node:assert';
+import { cpSync, mkdirSync, writeFileSync, utimesSync, statSync } from 'node:fs';
+import { join } from 'node:path';
+import tmpdir from '../common/tmpdir.js';
+
+tmpdir.refresh();
+
+// Build a source tree with a known past timestamp on directories.
+const src = nextdir();
+mkdirSync(join(src, 'subdir'), { recursive: true });
+writeFileSync(join(src, 'subdir', 'file.txt'), 'hello');
+
+const pastDate = new Date('2020-01-01T00:00:00Z');
+utimesSync(join(src, 'subdir', 'file.txt'), pastDate, pastDate);
+utimesSync(join(src, 'subdir'), pastDate, pastDate);
+utimesSync(src, pastDate, pastDate);
+
+// Copy with preserveTimestamps and a filter (to exercise the JS fallback path).
+const dest = nextdir();
+cpSync(src, dest, {
+  recursive: true,
+  preserveTimestamps: true,
+  filter: () => true,
+});
+
+// Verify file timestamps are preserved (existing behaviour).
+const srcFileStat = statSync(join(src, 'subdir', 'file.txt'));
+const destFileStat = statSync(join(dest, 'subdir', 'file.txt'));
+assert.strictEqual(srcFileStat.mtime.getTime(), destFileStat.mtime.getTime());
+
+// Verify directory timestamps are preserved (the bug fix).
+const srcDirStat = statSync(join(src, 'subdir'));
+const destDirStat = statSync(join(dest, 'subdir'));
+assert.strictEqual(srcDirStat.mtime.getTime(), destDirStat.mtime.getTime());
+
+const srcRootStat = statSync(src);
+const destRootStat = statSync(dest);
+assert.strictEqual(srcRootStat.mtime.getTime(), destRootStat.mtime.getTime());