int
_citrus_db_open(struct _citrus_db **rdb, struct _region *r, const char *magic,
_citrus_db_hash_func_t hashfunc, void *hashfunc_closure)
{
struct _citrus_db *db;
struct _citrus_db_header_x *dhx;
struct _memstream ms;
_memstream_bind(&ms, r);
/* sanity check */
dhx = _memstream_getregion(&ms, NULL, sizeof(*dhx));
if (dhx == NULL)
return (EFTYPE);
if (strncmp(dhx->dhx_magic, magic, _CITRUS_DB_MAGIC_SIZE) != 0)
return (EFTYPE);
if (_memstream_seek(&ms, be32toh(dhx->dhx_entry_offset), SEEK_SET))
return (EFTYPE);
if (be32toh(dhx->dhx_num_entries)*_CITRUS_DB_ENTRY_SIZE >
_memstream_remainder(&ms))
return (EFTYPE);
db = malloc(sizeof(*db));
if (db == NULL)
return (errno);
db->db_region = *r;
db->db_hashfunc = hashfunc;
db->db_hashfunc_closure = hashfunc_closure;
*rdb = db;
return (0);
}
int
_citrus_db_get_entry(struct _citrus_db *db, int idx,
struct _region *key, struct _region *data)
{
uint32_t num_entries;
size_t offset;
struct _memstream ms;
struct _citrus_db_header_x *dhx;
struct _citrus_db_entry_x *dex;
_memstream_bind(&ms, &db->db_region);
dhx = _memstream_getregion(&ms, NULL, sizeof(*dhx));
_DIAGASSERT(dhx);
num_entries = be32toh(dhx->dhx_num_entries);
if (idx < 0 || (uint32_t)idx >= num_entries)
return EINVAL;
/* seek to the next entry */
offset = be32toh(dhx->dhx_entry_offset) + idx * _CITRUS_DB_ENTRY_SIZE;
if (_citrus_memory_stream_seek(&ms, offset, SEEK_SET))
return EFTYPE;
/* get the entry record */
dex = _memstream_getregion(&ms, NULL, _CITRUS_DB_ENTRY_SIZE);
if (dex == NULL)
return EFTYPE;
/* seek to the head of the key. */
if (_memstream_seek(&ms, be32toh(dex->dex_key_offset), SEEK_SET))
return EFTYPE;
/* get the region of the key. */
if (_memstream_getregion(&ms, key, be32toh(dex->dex_key_size))==NULL)
return EFTYPE;
/* seek to the head of the data. */
if (_memstream_seek(&ms, be32toh(dex->dex_data_offset), SEEK_SET))
return EFTYPE;
/* get the region of the data. */
if (_memstream_getregion(&ms, data, be32toh(dex->dex_data_size))==NULL)
return EFTYPE;
return 0;
}
int
_citrus_db_lookup(struct _citrus_db *db, struct _citrus_region *key,
struct _citrus_region *data, struct _citrus_db_locator *dl)
{
struct _citrus_db_entry_x *dex;
struct _citrus_db_header_x *dhx;
struct _citrus_region r;
struct _memstream ms;
uint32_t hashval, num_entries;
size_t offset;
_memstream_bind(&ms, &db->db_region);
dhx = _memstream_getregion(&ms, NULL, sizeof(*dhx));
num_entries = be32toh(dhx->dhx_num_entries);
if (num_entries == 0)
return (ENOENT);
if (dl != NULL && dl->dl_offset>0) {
hashval = dl->dl_hashval;
offset = dl->dl_offset;
if (offset >= _region_size(&db->db_region))
return (ENOENT);
} else {
hashval = db->db_hashfunc(key)%num_entries;
offset = be32toh(dhx->dhx_entry_offset) +
hashval * _CITRUS_DB_ENTRY_SIZE;
if (dl)
dl->dl_hashval = hashval;
}
do {
/* seek to the next entry */
if (_citrus_memory_stream_seek(&ms, offset, SEEK_SET))
return (EFTYPE);
/* get the entry record */
dex = _memstream_getregion(&ms, NULL, _CITRUS_DB_ENTRY_SIZE);
if (dex == NULL)
return (EFTYPE);
/* jump to next entry having the same hash value. */
offset = be32toh(dex->dex_next_offset);
/* save the current position */
if (dl) {
dl->dl_offset = offset;
if (offset == 0)
dl->dl_offset = _region_size(&db->db_region);
}
/* compare hash value. */
if (be32toh(dex->dex_hash_value) != hashval)
/* not found */
break;
/* compare key length */
if (be32toh(dex->dex_key_size) == _region_size(key)) {
/* seek to the head of the key. */
if (_memstream_seek(&ms, be32toh(dex->dex_key_offset),
SEEK_SET))
return (EFTYPE);
/* get the region of the key */
if (_memstream_getregion(&ms, &r,
_region_size(key)) == NULL)
return (EFTYPE);
/* compare key byte stream */
if (memcmp(_region_head(&r), _region_head(key),
_region_size(key)) == 0) {
/* match */
if (_memstream_seek(
&ms, be32toh(dex->dex_data_offset),
SEEK_SET))
return (EFTYPE);
if (_memstream_getregion(
&ms, data,
be32toh(dex->dex_data_size)) == NULL)
return (EFTYPE);
return (0);
}
}
} while (offset != 0);
return (ENOENT);
}
