LDAP_SORT(3) OpenLDAP 2.2.23 (2005/01/24) LDAP_SORT(3)
NAME
ldap_sort_entries, ldap_sort_values, ldap_sort_strcasecmp -
LDAP sorting 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 comparison function to use when comparing
values (or individual DN components 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
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LDAP_SORT(3) OpenLDAP 2.2.23 (2005/01/24) LDAP_SORT(3)
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 ALSO
ldap(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.
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