char *
db_fetch(DB *db, const char *key)
{
char *ptr;
if (_db_find(db, key, 0) < 0) {
ptr = NULL; /* error, record not found */
db->cnt_fetcherr++;
} else {
ptr = _db_readdat(db); /* return pointer to data */
db->cnt_fetchok++;
}
/* Unlock the hash chain that _db_find() locked */
if (un_lock(db->idxfd, db->chainoff, SEEK_SET, 1) < 0)
err_dump("un_lock error");
return(ptr);
}
/* Deleting the specified record */
int db_delete(DB *db, const char *key)
{
int rc;
if(_db_find(db, key, 1) == 0)
{
rc = _db_dodelete(db); /* record found */
db->cnt_delok++;
}
else
{
rc = -1; /* not found */
db->cnt_delerr++;
}
if(un_lock(db->idxfd, db->chainoff, SEEK_SET, 1) < 0)
err_dump("error");
return(rc);
}
/* Storing a record in a database.
Return 0 if okay, Return 1 if record exists and DB_INSERT specified.
Return -1 if record doesn't exist and DB_REPLACE specified.
*/
int db_store(DB *db, const char *key, const char *data, int flag)
{
int rc, keylen, datlen;
off_t ptrval;
keylen = strlen(key);
datlen = strlen(data) + 1; /* +1 is for newline at the end */
if(datlen < DATLEN_MIN || datalen > DATLEN_MAX)
err_dump("invalid data length");
/* db_find() calculates which hash table this new record goes into(db->chainoff) whether it already exists or not.
The calls to _db_writeptr() below change the hash table entry for this chain to point to new record.
This means that the new record is added to the front of the hash chain */
if(_db_find(db, key, 1) < 0)
{
/* record not found*/
if(flag & DB_REPLACE)
{
rc = -1;
db->cnt_storerr++;
goto doreturn; /* error --- record doesn't exist */
}
/* do_find() locked the hash chain.
Reading the chain ptr to the first index record on hash chain */
ptrval = _db_readptr(db, db->chainoff);
if(_db_findfree(db, keylen, datlen) < 0)
{
/* an empty record of the correct record wasn't found.
we gotta append the new record to the ends of the index and data files */
_db_writedat(db, data, 0, SEEK_END);
_db_writeidx(db, key, 0, SEEK_END, ptrval);
/* db->idxoff was set by _db_writeidx()
The record goes to the front of the bash chain */
_db_writeptr(db, db->chainoff, db->idxoff);
db->cnt_stor1++;
}
else
{
/* Re-using an empty record
_db_findtree() removed the record from the free list and set both db->datoff and db->idxoff */
_db_writedat(db, data, 0, SEEK_END);
_db_writeidx(db, key, 0, SEEK_END, ptrval);
/* re-used record goes to the front of the hash chain */
_db_writeptr(db, db->chainoff, db->idxoff);
db->cnt_stor2++;
}
}
else
{
/* record found */
if(flag & DB_INSERT)
{
rc = 1;
db->cnt_storerr++;
goto doreturn; /* error --- record is already in the database */
}
/* We are replacing the existing record.
We know the new key equals the existing key, but also we gotta check if the data records are the same size. */
if(datlen != db->datlen)
{
_db_dodelete(db); /* delete the existing record */
/* Re-read the chain ptr in the hash table (It may change with the deletion) */
ptrval = _db_readptr(db, db->chainoff);
/* Appending new index and data records to end of files */
_db_writedat(db, data, 0, SEEK_END);
_db_writeidx(db, key, 0, SEEK_END, ptrval);
/* new record going to the front of the hash chain */
_db_writeptr(db, db->chainoff, db->idxoff);
db->cnt_stor3++;
}
else
{
/* Same sized data, just replaces data record */
_db_writedat(db, data, db->datoff, SEEK_SET);
db->cnt_stor4++;
}
}
rc = 0; /* woo hoo */
doreturn: /* unlock the hash chain that _db_find() locked */
if(un_lock(db->idxfd, db->chainoff, SEEK_SET, 1) < 0)
return(rc);
}