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112 lines
3.3 KiB
Groff
112 lines
3.3 KiB
Groff
.TH LDAP_SORT 3 "22 September 1998" "OpenLDAP LDVERSION"
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.\" $OpenLDAP$
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.\" Copyright 1998-1999 The OpenLDAP Foundation All Rights Reserved.
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.\" Copying restrictions apply. See COPYRIGHT/LICENSE.
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.SH NAME
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ldap_sort_entries, ldap_sort_values, ldap_sort_strcasecmp \- LDAP sorting routines
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.SH SYNOPSIS
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.nf
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.ft B
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#include <lber.h>
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#include <ldap.h>
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.LP
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.ft B
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ldap_sort_entries(ld, chain, attr, cmp)
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.ft
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LDAP *ld;
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LDAPMessage **chain;
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char *attr;
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int (*cmp)();
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.LP
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.ft B
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ldap_sort_values(ld, vals, cmp)
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.ft
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LDAP *ld;
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char **vals;
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int (*cmp)();
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.LP
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.ft B
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ldap_sort_strcasecmp(a, b)
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.ft
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char *a;
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char *b;
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.SH DESCRIPTION
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These routines are used to sort lists of entries and values retrieved
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from an LDAP server.
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.B ldap_sort_entries()
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is used to sort a chain
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of entries retrieved from an LDAP search call either by DN or by some
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arbitrary attribute in the entries. It takes \fIld\fP, the LDAP
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structure, which is only used for error reporting, \fIchain\fP, the
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list of entries as returned by
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.BR ldap_search_s (3)
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or
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.BR ldap_result (3).
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\fIattr\fP is the attribute to use as a key in the sort
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or NULL to sort by DN, and \fIcmp\fP is the comparison function to use
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when comparing values (or individual DN components if sorting by DN).
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In this case, \fIcmp\fP should be a function taking two single values
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of the \fIattr\fP to sort by, and returning a value less than zero,
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equal to zero, or greater than zero, depending on whether the first
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argument is less than, equal to, or greater than the second argument.
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The convention is the same as used by
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.BR qsort (3),
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which is called to do the actual sorting.
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.LP
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.B ldap_sort_values()
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is used to sort an array of values from an entry,
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as returned by
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.BR ldap_get_values (3).
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It takes the LDAP connection
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structure \fIld\fP, the array of values
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to sort \fIvals\fP, and \fIcmp\fP, the comparison
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function to use during the sort.
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Note that \fIcmp\fP will be passed a pointer to each element in the
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\fIvals\fP array, so if you pass the normal char ** for this parameter,
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\fIcmp\fP should take two char **'s as arguments (i.e., you cannot
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pass \fIstrcasecmp\fP or its friends for \fIcmp\fP). You can, however,
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pass the function
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.B ldap_sort_strcasecmp()
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for this purpose.
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.LP
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For example:
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.LP
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.nf
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.ft tt
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LDAP *ld;
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LDAPMessage *res;
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/* ... call to ldap_search_s(), fill in res, retrieve sn attr ... */
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/* now sort the entries on surname attribute */
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if ( ldap_sort_entries( ld, &res, "sn", ldap_sort_strcasecmp ) != 0 )
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ldap_perror( ld, "ldap_sort_entries" );
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.ft
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.fi
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.SH NOTES
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.LP
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The
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.B ldap_sort_entries()
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routine applies the comparison function to
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each value of the attribute in the array as returned by a call to
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.BR ldap_get_values (3),
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until a mismatch is found.
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This works fine for single-valued attributes, but
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may produce unexpected results for multi-valued attributes.
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When sorting by DN, the comparison function is
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applied to an exploded version of the DN, without types.
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The return values for all of these functions are declared in the
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<ldap.h> header file. Some routines may dynamically allocate memory.
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Callers are responsible for freeing such memory using the supplied
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deallocation routines.
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.SH SEE ALSO
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.BR ldap (3),
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.BR ldap_search (3),
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.BR ldap_result (3),
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.BR qsort (3)
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.SH ACKNOWLEDGEMENTS
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.B OpenLDAP
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is developed and maintained by The OpenLDAP Project (http://www.openldap.org/).
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.B OpenLDAP
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is derived from University of Michigan LDAP 3.3 Release.
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