genders_query - query genders database for a set of nodes
int genders_query(genders_t handle, char *nodes, int len, const char
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
nodes, genders_getnumnodes(3) should be used to determine the minimum
number of elements nodes should be able to store.
genders_nodelist_create(3) 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
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 genders_errnum(3) , and a description of the
error code can be retrieved via genders_strerror(3). Error codes are
defined in genders.h.
The handle parameter is NULL. The genders handle must be
created with genders_handle_create(3).
genders_load_data(3) has not been called to load genders data.
The list pointed to by nodes is not large enough to store all
An incorrect parameter has been passed in.
There is a syntax error in the query.
malloc(3) has failed internally, system is out of memory.
A null pointer has been found in the list passed in.
handle has an incorrect magic number. handle does not point to
a genders handle or handle has been destroyed by
An internal system error has occurred.
libgenders(3), genders_handle_create(3), genders_load_data(3),
genders_getnumnodes(3), genders_nodelist_create(3), genders_errnum(3),