LDAP_SORT(3)LDAP_SORT(3)NAME
ldap_sort_entries, ldap_sort_values, ldap_sort_strcasecmp - LDAP sort‐
ing routines
LIBRARY
OpenLDAP LDAP (libldap, -lldap)
SYNOPSIS
#include <ldap.h>
ldap_sort_entries(ld, chain, attr, cmp)
LDAP *ld;
LDAPMessage **chain;
char *attr;
int (*cmp)();
ldap_sort_values(ld, vals, cmp)
LDAP *ld;
char **vals;
int (*cmp)();
ldap_sort_strcasecmp(a, b)
char *a;
char *b;
DESCRIPTION
These routines are used to sort lists of entries and values retrieved
from an LDAP server. ldap_sort_entries() is used to sort a chain of
entries retrieved from an LDAP search call either by DN or by some
arbitrary attribute in the entries. It takes ld, the LDAP structure,
which is only used for error reporting, chain, the list of entries as
returned by ldap_search_s(3) or ldap_result(3). attr is the attribute
to use as a key in the sort or NULL to sort by DN, and cmp is the com‐
parison function to use when comparing values (or individual DN compo‐
nents if sorting by DN). In this case, cmp should be a function taking
two single values of the attr to sort by, and returning a value less
than zero, equal to zero, or greater than zero, depending on whether
the first argument is less than, equal to, or greater than the second
argument. The convention is the same as used by qsort(3), which is
called to do the actual sorting.
ldap_sort_values() is used to sort an array of values from an entry, as
returned by ldap_get_values(3). It takes the LDAP connection structure
ld, the array of values to sort vals, and cmp, the comparison function
to use during the sort. Note that cmp will be passed a pointer to each
element in the vals array, so if you pass the normal char ** for this
parameter, cmp should take two char **'s as arguments (i.e., you cannot
pass strcasecmp or its friends for cmp). You can, however, pass the
function ldap_sort_strcasecmp() for this purpose.
For example:
LDAP *ld;
LDAPMessage *res;
/*
* ... call to ldap_search_s(), fill in res,
* retrieve sn attr ...
*/
/* now sort the entries on surname attribute */
if ( ldap_sort_entries( ld, &res, "sn",
ldap_sort_strcasecmp ) != 0 )
ldap_perror( ld, "ldap_sort_entries" );
NOTES
The ldap_sort_entries() routine applies the comparison function to each
value of the attribute in the array as returned by a call to
ldap_get_values(3), until a mismatch is found. This works fine for
single-valued attributes, but may produce unexpected results for multi-
valued attributes. When sorting by DN, the comparison function is
applied to an exploded version of the DN, without types. The return
values for all of these functions are declared in the <ldap.h> header
file. Some routines may dynamically allocate memory. Callers are
responsible for freeing such memory using the supplied deallocation
routines.
SEE ALSOldap(3), ldap_search(3), ldap_result(3), qsort(3)ACKNOWLEDGEMENTS
OpenLDAP is developed and maintained by The OpenLDAP Project
(http://www.openldap.org/). OpenLDAP is derived from University of
Michigan LDAP 3.3 Release.
OpenLDAP 2.3.43 2008/07/16 LDAP_SORT(3)
