int (*read_handler)(struct main_file *fi); /* [*] To be called when ready for reading/writing; must call file_chg() afterwards */
int (*write_handler)(struct main_file *fi);
void *data; /* [*] Data for use by the handlers */
int (*read_handler)(struct main_file *fi); /* [*] To be called when ready for reading/writing; must call file_chg() afterwards */
int (*write_handler)(struct main_file *fi);
void *data; /* [*] Data for use by the handlers */