FileManger: Fix file descriptor leak in copy_file_or_directory, found by Coverity

Author: https://github.com/bgianfo
Commit: e43d5d5eaa
Pull-request: https://github.com/SerenityOS/serenity/pull/3184
Reviewed-by: https://github.com/awesomekling
Reviewed-by: https://github.com/bugaevc

Applications/FileManager/FileUtils.cpp

@@ -26,6 +26,7 @@
 
 #include "FileUtils.h"
 #include <AK/LexicalPath.h>
+#include <AK/ScopeGuard.h>
 #include <AK/StringBuilder.h>
 #include <LibCore/DirIterator.h>
 #include <stdio.h>
@@ -86,6 +87,8 @@ bool copy_file_or_directory(const String& src_path, const String& dst_path)
         return false;
     }
 
+    ScopeGuard close_fd_guard([src_fd]() { close(src_fd); });
+
     struct stat src_stat;
     int rc = fstat(src_fd, &src_stat);
     if (rc < 0) {