/**
+ * Path of a file that is possibly stored inside another file.
+ * The #fs_path points to a file at the file system. This can be either the file expressed by
+ * the #FilePath object, or a container file like a tar-file. In the latter case, the
+ * #contained_path is the lower-case path to the expressed file inside the container file.
+ */
+class FilePath {
+public:
+       FilePath() : fs_path(""), contained_path("") { }
+       FilePath(const std::string &fs_path) : fs_path(fs_path), contained_path("") { }
+       FilePath(const std::string &fs_path, const std::string &contained_path) : fs_path(fs_path), contained_path(strlower(contained_path)) { }
+
+       std::string fs_path;        ///< Path to a file at the file system.
+       std::string contained_path; ///< If not empty, lower-case path inside the #fs_path file.


diff --git a/src/newgrf_config.h b/src/newgrf_config.h
--- a/src/newgrf_config.h
+++ b/src/newgrf_config.h
@@ -151,13 +151,15 @@ struct GRFTextWrapper : public SimpleCou
 
 /** Information about GRF, used in the game and (part of it) in savegames */
 struct GRFConfig : ZeroedMemoryAllocator {
-       GRFConfig(const char *filename = NULL);
+       GRFConfig();
+       GRFConfig(const FilePath &file_path);
        GRFConfig(const GRFConfig &config);
        ~GRFConfig();
 
        GRFIdentifier ident;                           ///< grfid and md5sum to uniquely identify newgrfs
        uint8 original_md5sum[16];                     ///< MD5 checksum of original file if only a 'compatible' file was loaded
-       char *filename;                                ///< Filename - either with or without full path
+//     char *filename;                                ///< Filename - either with or without full path
+       FilePath file_path;                            ////< Path to the file.
        GRFTextWrapper *name;                          ///< NOSAVE: GRF name (Action 0x08)
        GRFTextWrapper *info;                          ///< NOSAVE: GRF info (author, copyright, ...) (Action 0x08)
        GRFTextWrapper *url;                           ///< NOSAVE: URL belonging to this GRF.