namedb: implemented GEQ/LEQ for lmdb backend + tests

src/common/namedb/namedb_lmdb.c

@@ -213,7 +213,7 @@ static knot_iter_t *iter_set(knot_iter_t *iter, knot_val_t *key, unsigned flags)
 	case KNOT_NAMEDB_LAST:  op = MDB_LAST;  break;
 	case KNOT_NAMEDB_NEXT:  op = MDB_NEXT; break;
 	case KNOT_NAMEDB_PREV:  op = MDB_PREV; break;
-	case KNOT_NAMEDB_LEQ:   assert(0); /* ENOTSUP */ break;
+	case KNOT_NAMEDB_LEQ:
 	case KNOT_NAMEDB_GEQ:   op = MDB_SET_RANGE; break;
 	default: break;
 	}
@@ -225,7 +225,20 @@ static knot_iter_t *iter_set(knot_iter_t *iter, knot_val_t *key, unsigned flags)
 	}
 	
 	int ret = mdb_cursor_get(cursor, key ? &db_key : NULL, NULL, op);
-	if (ret != 0) {
+
+	/* LEQ is not supported in LMDB, workaround using GEQ. */
+	if (flags == KNOT_NAMEDB_LEQ && key) {
+		/* Searched key is after the last key. */
+		if (ret != MDB_SUCCESS) {
+			return iter_set(iter, NULL, KNOT_NAMEDB_LAST);
+		}
+		/* If the searched key != matched, get previous. */
+		if ((key->len != db_key.mv_size) || (memcmp(key->data, db_key.mv_data, key->len) != 0)) {
+			return iter_set(iter, NULL, KNOT_NAMEDB_PREV);
+		}
+	}
+
+	if (ret != MDB_SUCCESS) {
 		mdb_cursor_close(cursor);
 		return NULL;
 	}

tests/namedb.c

@@ -171,6 +171,24 @@ static void namedb_test_set(unsigned nkeys, char **keys, char *dbid,
 		it = api->iter_seek(it, &key, KNOT_NAMEDB_LAST);
 		ret = api->iter_key(it, &key);
 		is_string(last_key, key.data, "%s: iter_set(LAST)", api->name);
+		/* Check if prev(last_key + 1) is the last_key */
+		strcpy(key_buf, last_key);
+		key_buf[0] += 1;
+		KEY_SET(key, key_buf);
+		it = api->iter_seek(it, &key, KNOT_NAMEDB_LEQ);
+		assert(it);
+		ret = api->iter_key(it, &key);
+		is_int(0, ret, "LEQ ret");
+		is_string(last_key, key.data, "%s: iter_set(LEQ)", api->name);
+		/* Check if next(first_key - 1) is the first_key */
+		strcpy(key_buf, first_key);
+		key_buf[0] -= 1;
+		KEY_SET(key, key_buf);
+		it = api->iter_seek(it, &key, KNOT_NAMEDB_GEQ);
+		assert(it);
+		ret = api->iter_key(it, &key);
+		is_int(0, ret, "GEQ ret");
+		is_string(first_key, key.data, "%s: iter_set(GEQ)", api->name);
 	}
 	api->iter_finish(it);