int genders_query(genders_t handle, char *nodes, int len, const char *query);
genders_query() queries the genders database for a set of nodes
based on the union, intersection, difference, or complement of genders
attributes and values. The query for a set of nodes is passed as a
string through the query parameter. The set operation union is
represented by two pipe symbols ('||'), intersection by two ampersand
symbols ('&&'), difference by two minus symbols ('--'), and complement
by a tilde ('~'). Set operations are performed left to right.
Parentheses may be used to change the order of operations. A list of
query examples are listed below. A NULL query retrieves all nodes
from the genders database.
The nodes from the query are stored in the list pointed to
by nodes. len indicates the number of nodes that can be
stored in the list.
To avoid passing in a list that is not large enough to store all the
should be used to determine the minimum number of elements nodes
should be able to store.
could be used to create a list that is guaranteed to be large enough
to store all of the nodes.
The following are example queries that can be
passed to genders_query().
Determine the set of nodes with the mgmt or login attribute:
Determine the set of nodes that are not login nodes:
Determine the set of nodes that both login nodes and ntp servers:
Determine the set of nodes that are not mgmt or login nodes:
On success, the number of nodes stored in nodes is returned. On
error, -1 is returned, and an error code is returned in handle.
The error code can be retrieved via
, and a description of the error code can be retrieved via
Error codes are defined in genders.h.