win,fs: use namespaced path in absolute symlinks

bzoz · bzoz · commit a4e273baf439 · 2020-05-21T14:12:42.000+02:00
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
@@ -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, '\\');
 }
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));
+}));

Original file line number	Diff line number	Diff line change
`@@ -302,6 +302,10 @@ function preprocessSymlinkDestination(path, type, linkPath) {`
`302`	`302`	`path = pathModule.resolve(linkPath, '..', path);`
`303`	`303`	`return pathModule.toNamespacedPath(path);`
`304`	`304`	`}`
	`305`	`+ if (pathModule.isAbsolute(path)) {`
	`306`	`+ // If the path is absolute, use the \\?\-prefix to enable long filenames`
	`307`	`+ return pathModule.toNamespacedPath(path);`
	`308`	`+ }`
`305`	`309`	`// Windows symlinks don't tolerate forward slashes.`
`306`	`310`	`return ('' + path).replace(/\//g, '\\');`
`307`	`311`	`}`