From 3b46e7f1485c62935b2cb1a66bee82fdca738660 Mon Sep 17 00:00:00 2001
From: Bartosz Sosnowski <bartosz@janeasystems.com>
Date: Thu, 21 May 2020 14:12:42 +0200
Subject: [PATCH] win,fs: use namespaced path in absolute symlinks
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Use the namespaced (with the \\?\ prefix) paths for symlink targets when
the path is absolute. This allows creation of symlinks to files with
long filenames.

Fixes: https://github.com/nodejs/node/issues/27795

PR-URL: https://github.com/nodejs/node/pull/33351
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Gerhard Stöbich <deb2001-github@yahoo.de>
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Ruben Bridgewater <ruben@bridgewater.de>
---
 lib/internal/fs/utils.js                  | 10 +++++---
 test/parallel/test-fs-symlink-longpath.js | 29 +++++++++++++++++++++++
 2 files changed, 36 insertions(+), 3 deletions(-)
 create mode 100644 test/parallel/test-fs-symlink-longpath.js

diff --git a/lib/internal/fs/utils.js b/lib/internal/fs/utils.js
index 6f096336f20e10..989bccc7c153d3 100644
--- a/lib/internal/fs/utils.js
+++ b/lib/internal/fs/utils.js
@@ -272,10 +272,14 @@ function preprocessSymlinkDestination(path, type, linkPath) {
     // A relative target is relative to the link's parent directory.
     path = pathModule.resolve(linkPath, '..', path);
     return pathModule.toNamespacedPath(path);
-  } else {
-    // Windows symlinks don't tolerate forward slashes.
-    return ('' + path).replace(/\//g, '\\');
   }
+
+  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, '\\');
 }
 
 // Constructor for file stats.
diff --git a/test/parallel/test-fs-symlink-longpath.js b/test/parallel/test-fs-symlink-longpath.js
new file mode 100644
index 00000000000000..f6824218137bf2
--- /dev/null
+++ b/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));
+}));