int mdb_dbi_open()

in lib/Database/lmdb/mdb.c [10768:10885]

• 92 lines of code
• 26 McCabe index (conditional complexity)

int mdb_dbi_open(MDB_txn *txn, const char *name, unsigned int flags, MDB_dbi *dbi)
{
	MDB_val key, data;
	MDB_dbi i;
	MDB_cursor mc;
	MDB_db dummy;
	int rc, dbflag, exact;
	unsigned int unused = 0, seq;
	char *namedup;
	size_t len;

	if (flags & ~VALID_FLAGS)
		return EINVAL;
	if (txn->mt_flags & MDB_TXN_BLOCKED)
		return MDB_BAD_TXN;

	/* main DB? */
	if (!name) {
		*dbi = MAIN_DBI;
		if (flags & PERSISTENT_FLAGS) {
			uint16_t f2 = flags & PERSISTENT_FLAGS;
			/* make sure flag changes get committed */
			if ((txn->mt_dbs[MAIN_DBI].md_flags | f2) != txn->mt_dbs[MAIN_DBI].md_flags) {
				txn->mt_dbs[MAIN_DBI].md_flags |= f2;
				txn->mt_flags |= MDB_TXN_DIRTY;
			}
		}
		mdb_default_cmp(txn, MAIN_DBI);
		return MDB_SUCCESS;
	}

	if (txn->mt_dbxs[MAIN_DBI].md_cmp == NULL) {
		mdb_default_cmp(txn, MAIN_DBI);
	}

	/* Is the DB already open? */
	len = strlen(name);
	for (i=CORE_DBS; i<txn->mt_numdbs; i++) {
		if (!txn->mt_dbxs[i].md_name.mv_size) {
			/* Remember this free slot */
			if (!unused) unused = i;
			continue;
		}
		if (len == txn->mt_dbxs[i].md_name.mv_size &&
			!strncmp(name, txn->mt_dbxs[i].md_name.mv_data, len)) {
			*dbi = i;
			return MDB_SUCCESS;
		}
	}

	/* If no free slot and max hit, fail */
	if (!unused && txn->mt_numdbs >= txn->mt_env->me_maxdbs)
		return MDB_DBS_FULL;

	/* Cannot mix named databases with some mainDB flags */
	if (txn->mt_dbs[MAIN_DBI].md_flags & (MDB_DUPSORT|MDB_INTEGERKEY))
		return (flags & MDB_CREATE) ? MDB_INCOMPATIBLE : MDB_NOTFOUND;

	/* Find the DB info */
	dbflag = DB_NEW|DB_VALID|DB_USRVALID;
	exact = 0;
	key.mv_size = len;
	key.mv_data = (void *)name;
	mdb_cursor_init(&mc, txn, MAIN_DBI, NULL);
	rc = mdb_cursor_set(&mc, &key, &data, MDB_SET, &exact);
	if (rc == MDB_SUCCESS) {
		/* make sure this is actually a DB */
		MDB_node *node = NODEPTR(mc.mc_pg[mc.mc_top], mc.mc_ki[mc.mc_top]);
		if ((node->mn_flags & (F_DUPDATA|F_SUBDATA)) != F_SUBDATA)
			return MDB_INCOMPATIBLE;
	} else {
		if (rc != MDB_NOTFOUND || !(flags & MDB_CREATE))
			return rc;
		if (F_ISSET(txn->mt_flags, MDB_TXN_RDONLY))
			return EACCES;
	}

	/* Done here so we cannot fail after creating a new DB */
	if ((namedup = strdup(name)) == NULL)
		return ENOMEM;

	if (rc) {
		/* MDB_NOTFOUND and MDB_CREATE: Create new DB */
		data.mv_size = sizeof(MDB_db);
		data.mv_data = &dummy;
		memset(&dummy, 0, sizeof(dummy));
		dummy.md_root = P_INVALID;
		dummy.md_flags = flags & PERSISTENT_FLAGS;
		WITH_CURSOR_TRACKING(mc,
			rc = mdb_cursor_put(&mc, &key, &data, F_SUBDATA));
		dbflag |= DB_DIRTY;
	}

	if (rc) {
		free(namedup);
	} else {
		/* Got info, register DBI in this txn */
		unsigned int slot = unused ? unused : txn->mt_numdbs;
		txn->mt_dbxs[slot].md_name.mv_data = namedup;
		txn->mt_dbxs[slot].md_name.mv_size = len;
		txn->mt_dbxs[slot].md_rel = NULL;
		txn->mt_dbflags[slot] = dbflag;
		/* txn-> and env-> are the same in read txns, use
		 * tmp variable to avoid undefined assignment
		 */
		seq = ++txn->mt_env->me_dbiseqs[slot];
		txn->mt_dbiseqs[slot] = seq;

		memcpy(&txn->mt_dbs[slot], data.mv_data, sizeof(MDB_db));
		*dbi = slot;
		mdb_default_cmp(txn, slot);
		if (!unused) {
			txn->mt_numdbs++;
		}
	}

	return rc;
}