win,fs: use namespaced path in absolute symlinks

bzoz · codebytere · commit 3b46e7f1485c · 2020-07-07T22:35:41.000-07:00
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: #27795 PR-URL: #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>
diff --git 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
@@ -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));
+}));
