Made wesnoth set data path to directory in which it's located...

...if data/_main.cfg exists in it.

src/filesystem.cpp

@@ -31,6 +31,7 @@
 #else /* !_WIN32 */
 #include <unistd.h>
 #include <dirent.h>
+#include <libgen.h>
 #endif /* !_WIN32 */
 
 #ifdef __BEOS__
@@ -405,6 +406,20 @@ std::string get_cwd()
 	}
 }
 
+std::string get_exe_dir()
+{
+#ifndef _WIN32
+	char buf[1024];
+	size_t path_size = readlink("/proc/self/exe", buf, 1024);
+	if(path_size == -1)
+		return std::string();
+	buf[path_size] = 0;
+	return std::string(dirname(buf));
+#else
+	return std::string();
+#endif
+}
+
 bool create_directory_if_missing(const std::string& dirname)
 {
 	if(is_directory(dirname)) {

src/filesystem.hpp

@@ -79,6 +79,7 @@ std::string get_upload_dir();
 const std::string& get_user_data_dir();
 
 std::string get_cwd();
+std::string get_exe_dir();
 
 bool make_directory(const std::string& dirname);
 bool delete_directory(const std::string& dirname);

src/game.cpp

@@ -2264,6 +2264,13 @@ int main(int argc, char** argv)
 		} else {
 			std::cerr << "Wesnoth doesn't have the name wesnoth, so can't locate the server.\n";
 		}
+
+		std::string exe_dir = get_exe_dir();
+		if(!exe_dir.empty() && file_exists(exe_dir + "/data/_main.cfg")) {
+			std::cerr << "Found a data directory at " + exe_dir + ", setting path to it.\n";
+			game_config::path = exe_dir;
+		}
+
 		std::cerr << "Battle for Wesnoth v" << game_config::revision << '\n';
 		time_t t = time(NULL);
 		std::cerr << "Started on " << ctime(&t) << "\n";