-int rrd_open(char *file_name, FILE **in_file, rrd_t *rrd, int rdwr);
-int rrd_open_r(char *file_name, FILE **in_file, rrd_t *rrd, int rdwr);
-int readfile(char *file, char **buffer, int skipfirst);
-int readfile_r(char *file, char **buffer, int skipfirst);
+int rrd_open(const char *file_name, FILE **in_file, rrd_t *rrd, int rdwr);
+int readfile(const char *file, char **buffer, int skipfirst);