typedef struct MetaBlock MetaBlock;typedef struct MetaEntry MetaEntry; #define MaxBlock (1UL<<31) enum {	BytesPerEntry = 100,	/* estimate of bytes per dir entries - determines number of index entries in the block */	FullPercentage = 80,	/* don't allocate in block if more than this percentage full */	FlushSize = 200,	/* number of blocks to flush */	DirtyPercentage = 50	/* maximum percentage of dirty blocks */};  struct MetaEntry{	uchar *p;	ushort size;}; struct MetaBlock{	int maxsize;		/* size of block */	int size;		/* size used */	int free;		/* free space within used size */	int maxindex;		/* entries allocated for table */	int nindex;		/* amount of table used */	int unbotch;	uchar *buf;}; struct VacDirEnum{	VacFile *file;	u32int boff;	int i, n;	VacDir *buf;};