-struct hive_h {
- char *filename;
- int fd;
- size_t size;
- int msglvl;
- int writable;
-
- /* Registry file, memory mapped if read-only, or malloc'd if writing. */
- union {
- char *addr;
- struct ntreg_header *hdr;
- };
-
- /* Use a bitmap to store which file offsets are valid (point to a
- * used block). We only need to store 1 bit per 32 bits of the file
- * (because blocks are 4-byte aligned). We found that the average
- * block size in a registry file is ~50 bytes. So roughly 1 in 12
- * bits in the bitmap will be set, making it likely a more efficient
- * structure than a hash table.
- */
- char *bitmap;
-#define BITMAP_SET(bitmap,off) (bitmap[(off)>>5] |= 1 << (((off)>>2)&7))
-#define BITMAP_CLR(bitmap,off) (bitmap[(off)>>5] &= ~ (1 << (((off)>>2)&7)))
-#define BITMAP_TST(bitmap,off) (bitmap[(off)>>5] & (1 << (((off)>>2)&7)))
-#define IS_VALID_BLOCK(h,off) \
- (((off) & 3) == 0 && \
- (off) >= 0x1000 && \
- (off) < (h)->size && \
- BITMAP_TST((h)->bitmap,(off)))
-
- /* Fields from the header, extracted from little-endianness hell. */
- size_t rootoffs; /* Root key offset (always an nk-block). */
- size_t endpages; /* Offset of end of pages. */
-
- /* For writing. */
- size_t endblocks; /* Offset to next block allocation (0
- if not allocated anything yet). */
-};
-