LDAP_SORT(3)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 val-
ues 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 con-
vention 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 ele-
ment in the vals array, so if you pass the normal char **
for this parameter, cmp should take two char **'s as argu-
ments (i.e., you cannot pass strcasecmp or its friends for
cmp). You can, however, pass the function ldap_sort_str-
casecmp() 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 rou-
tines.
SEE ALSOldap(3), ldap_search(3), ldap_result(3), qsort(3)ACKNOWLEDGEMENTS
OpenLDAP is developed and maintained by The OpenLDAP Pro-
ject (http://www.openldap.org/). OpenLDAP is derived from
University of Michigan LDAP 3.3 Release.
OpenLDAP LDVERSION RELEASEDATE LDAP_SORT(3)
