fs: throw on existing dir in cpSync with errorOnExist

cpSync() did not honor errorOnExist when the destination directory
already existed, while the asynchronous cp() does (fixed in the commit
that added test-fs-cp-async-dir-exists-error-on-exist). Mirror that
guard in the synchronous onDir() so both APIs behave identically.

Signed-off-by: Daijiro Wachi <daijiro.wachi@gmail.com>
PR-URL: #64124
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

Author: watilde

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

@@ -134,6 +134,15 @@ function setDestTimestamps(src, dest) {
 // TODO(@anonrig): Move this function to C++.
 function onDir(srcStat, destStat, src, dest, opts) {
   if (!destStat) return copyDir(src, dest, opts, true, srcStat.mode);
+  if (opts.errorOnExist && !opts.force) {
+    throw new ERR_FS_CP_EEXIST({
+      message: `${dest} already exists`,
+      path: dest,
+      syscall: 'cp',
+      errno: EEXIST,
+      code: 'EEXIST',
+    });
+  }
   return copyDir(src, dest, opts);
 }
 

test/parallel/test-fs-cp-sync-dir-exists-error-on-exist.mjs

@@ -0,0 +1,32 @@
+// This tests that cpSync() throws if errorOnExist is true, force is false,
+// and the destination directory already exists (even if contents don't
+// conflict), matching the asynchronous cp() behavior.
+
+import '../common/index.mjs';
+import { nextdir } from '../common/fs.js';
+import assert from 'node:assert';
+import { cpSync, mkdirSync, writeFileSync } from 'node:fs';
+import tmpdir from '../common/tmpdir.js';
+
+tmpdir.refresh();
+
+const src = nextdir();
+const dest = nextdir();
+
+// Create source directory with a file
+mkdirSync(src);
+writeFileSync(`${src}/file.txt`, 'test');
+
+// Create destination directory with a different (non-conflicting) file
+mkdirSync(dest);
+writeFileSync(`${dest}/other.txt`, 'existing');
+
+// Should throw because dest directory already exists
+assert.throws(
+  () => cpSync(src, dest, {
+    recursive: true,
+    errorOnExist: true,
+    force: false,
+  }),
+  { code: 'ERR_FS_CP_EEXIST' },
+);