win,fs: use namespaced path in absolute symlinks

lib/internal/fs/utils.js

@@ -302,6 +302,10 @@ function preprocessSymlinkDestination(path, type, linkPath) {
     path = pathModule.resolve(linkPath, '..', path);
     return pathModule.toNamespacedPath(path);
   }
+  if (pathModule.isAbsolute(path)) {
+    // If the path is absolute, use the \\?\-prefix to enable long filenames
+    return pathModule.toNamespacedPath(path);
+  }
   // Windows symlinks don't tolerate forward slashes.
   return ('' + path).replace(/\//g, '\\');
 }

test/parallel/test-fs-symlink-longpath.js

@@ -0,0 +1,29 @@
+'use strict';
+
+const common = require('../common');
+const assert = require('assert');
+const path = require('path');
+const fs = require('fs');
+
+const tmpdir = require('../common/tmpdir');
+tmpdir.refresh();
+const tmpDir = tmpdir.path;
+const longPath = path.join(...[tmpDir].concat(Array(30).fill('1234567890')));
+fs.mkdirSync(longPath, { recursive: true });
+
+// Test if we can have symlinks to files and folders with long filenames
+const targetDirtectory = path.join(longPath, 'target-directory');
+fs.mkdirSync(targetDirtectory);
+const pathDirectory = path.join(tmpDir, 'new-directory');
+fs.symlink(targetDirtectory, pathDirectory, 'dir', common.mustCall((err) => {
+  assert.ifError(err);
+  assert(fs.existsSync(pathDirectory));
+}));
+
+const targetFile = path.join(longPath, 'target-file');
+fs.writeFileSync(targetFile, 'data');
+const pathFile = path.join(tmpDir, 'new-file');
+fs.symlink(targetFile, pathFile, common.mustCall((err) => {
+  assert.ifError(err);
+  assert(fs.existsSync(pathFile));
+}));