ssize_t (*fetch)(struct krb5_storage_data*, void*, size_t);
ssize_t (*store)(struct krb5_storage_data*, const void*, size_t);
off_t (*seek)(struct krb5_storage_data*, off_t, int);
+ int (*trunc)(struct krb5_storage_data*, off_t);
void (*free)(struct krb5_storage_data*);
krb5_flags flags;
int eof_code;