NAME

       genders_query - query genders database for a set of nodes

SYNOPSIS

       #include <genders.h>

       int genders_query(genders_t handle, char *nodes[], int len, const char *query);

DESCRIPTION

       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.

EXAMPLES

       The following are example queries that can be passed to genders_query().

       Determine the set of nodes with the mgmt or login attribute:
               "mgmt||login"

       Determine the set of nodes that are not login nodes:
               "all--login"

       Determine the set of nodes that both login nodes and ntp servers:
               "login&&ntpserv"

       Determine the set of nodes that are not mgmt or login nodes:
               "~(mgmt||login)"

RETURN VALUES

       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.

ERRORS

       GENDERS_ERR_NULLHANDLE
              The   handle   parameter  is  NULL.   The  genders  handle  must  be  created  with
              genders_handle_create(3).

       GENDERS_ERR_NOTLOADED
              genders_load_data(3) has not been called to load genders data.

       GENDERS_ERR_OVERFLOW
              The list pointed to by nodes is not large enough to store all the nodes.

       GENDERS_ERR_PARAMETERS
              An incorrect parameter has been passed in.

       GENDERS_ERR_SYNTAX
              There is a syntax error in the query.

       GENDERS_ERR_OUTMEM
              malloc(3) has failed internally, system is out of memory.

       GENDERS_ERR_NULLPTR
              A null pointer has been found in the list passed in.

       GENDERS_ERR_MAGIC
              handle has an incorrect magic number.  handle does not point to a genders handle or
              handle has been destroyed by genders_handle_destroy(3).

       GENDERS_ERR_INTERNAL
              An internal system error has occurred.

FILES

       /usr/include/genders.h

SEE ALSO

       libgenders(3),   genders_handle_create(3),  genders_load_data(3),  genders_getnumnodes(3),
       genders_nodelist_create(3), genders_errnum(3), genders_strerror(3)