void bufchain_init(bufchain *ch);
void bufchain_clear(bufchain *ch);
int bufchain_size(bufchain *ch);
-void bufchain_add(bufchain *ch, void *data, int len);
+void bufchain_add(bufchain *ch, const void *data, int len);
void bufchain_prefix(bufchain *ch, void **data, int *len);
void bufchain_consume(bufchain *ch, int len);
void bufchain_fetch(bufchain *ch, void *data, int len);