ldap_sort_entries(3ldap)
ldap_sort_entries, ldap_sort_values, ldap_sort_strcasecmp --
LDAP sorting routines
Synopsis
#include <lber.h>
#include <ldap.h>
ldap_sort_entries(LDAP
ld, LDAPMessage 
chain, char
attr, int (
cmp)());
ldap_sort_values(LDAP
ld, char 
vals, int (
cmp)());
ldap_sort_strcasecmp(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, and chain, the list of entries as returned by
ldap_search_s(3ldap)
or
ldap_result(3ldap).
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(3C),
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(3ldap).
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 (that is, you cannot pass
strcasecmp or associated functions 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" );
Warnings
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(3ldap),
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
malloc memory.
References
Intro(3ldap),
ldap_result(3ldap),
ldap_search(3ldap),
qsort(3C)
30 January 1998
© 1998 The Santa Cruz Operation, Inc. All rights reserved.