ldap_sort_entries, ldap_sort_values, ldap_sort_strcasecmp - LDAP sorting routines
ldap_sort_entries(ld, chain, attr, cmp)
ldap_sort_values(ld, vals, cmp)
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 struc-
ture, 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 str-
casecmp or its friends for cmp). You can, however, pass the function ldap_sort_str-
casecmp() for this purpose.
/* ... 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" );
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.
ldap(3), ldap_search(3), ldap_result(3), qsort(3)
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 2.0.27-Release 22 September 1998 LDAP_SORT(3)