Patch up race condition in symlink copying.

Author: vladikoff

Diff for: CHANGELOG

@@ -1,3 +1,7 @@
+v1.5.3
+  date: 2022-04-23
+  changes:
+    - Patch up race condition in symlink copying.
 v1.5.2
   date: 2022-04-12
   changes:

Diff for: lib/grunt/file.js

@@ -294,11 +294,6 @@ file.write = function(filepath, contents, options) {
 // processing content, writing output.
 // Handles symlinks by coping them as files or directories.
 file.copy = function copy(srcpath, destpath, options) {
-  if (file.isLink(destpath)) {
-    // in case destpath is a symlink, avoid following the symlink, instead overwrite it later
-    fs.unlinkSync(destpath);
-  }
-
   if (file.isLink(srcpath)) {
     file._copySymbolicLink(srcpath, destpath);
   } else if (file.isDir(srcpath)) {
@@ -338,8 +333,8 @@ file._copy = function(srcpath, destpath, options) {
     }
   }
   // Abort copy if the process function returns false.
-  if (contents === false) {
-    grunt.verbose.writeln('Write aborted.');
+  if (contents === false || file.isLink(destpath)) {
+    grunt.verbose.writeln('Write aborted. Either the process function returned false or the destination is a symlink');
   } else {
     file.write(destpath, contents, readWriteOptions);
   }

Diff for: test/grunt/file_test.js

@@ -916,5 +916,13 @@ exports.file = {
       test.ok(fs.lstatSync(path.join(destdir.path, path.basename(fixtures))).isSymbolicLink());
       test.done();
     },
-  }
+  },
+  'symbolicLinkDestError': function(test) {
+    test.expect(1);
+    var tmpfile = new Tempdir();
+    fs.symlinkSync(path.resolve('test/fixtures/octocat.png'), path.join(tmpfile.path, 'octocat.png'), 'file');
+    grunt.file.copy(path.resolve('test/fixtures/octocat.png'), path.join(tmpfile.path, 'octocat.png'));
+    test.ok(fs.lstatSync(path.join(tmpfile.path, 'octocat.png')).isSymbolicLink());
+    test.done();
+  },
 };