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+/* avl.c - routines to implement an avl tree */
+/* $OpenLDAP$ */
+/* This work is part of OpenLDAP Software <http://www.openldap.org/>.
+ *
+ * Copyright 1998-2022 The OpenLDAP Foundation.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted only as authorized by the OpenLDAP
+ * Public License.
+ *
+ * A copy of this license is available in the file LICENSE in the
+ * top-level directory of the distribution or, alternatively, at
+ * <http://www.OpenLDAP.org/license.html>.
+ */
+/* Portions Copyright (c) 1993 Regents of the University of Michigan.
+ * All rights reserved.
+ *
+ * Redistribution and use in source and binary forms are permitted
+ * provided that this notice is preserved and that due credit is given
+ * to the University of Michigan at Ann Arbor. The name of the University
+ * may not be used to endorse or promote products derived from this
+ * software without specific prior written permission. This software
+ * is provided ``as is'' without express or implied warranty.
+ */
+/* ACKNOWLEDGEMENTS:
+ * This work was originally developed by the University of Michigan
+ * (as part of U-MICH LDAP). Additional significant contributors
+ * include:
+ * Howard Y. Chu
+ * Hallvard B. Furuseth
+ * Kurt D. Zeilenga
+ */
+
+#include "portable.h"
+
+#include <limits.h>
+#include <stdio.h>
+#include <ac/stdlib.h>
+
+#ifdef CSRIMALLOC
+#define ber_memalloc malloc
+#define ber_memrealloc realloc
+#define ber_memfree free
+#else
+#include "lber.h"
+#endif
+
+#define AVL_INTERNAL
+#include "ldap_avl.h"
+
+/* Maximum tree depth this host's address space could support */
+#define MAX_TREE_DEPTH (sizeof(void *) * CHAR_BIT)
+
+static const int avl_bfs[] = {LH, RH};
+
+/*
+ * ldap_avl_insert -- insert a node containing data data into the avl tree
+ * with root root. fcmp is a function to call to compare the data portion
+ * of two nodes. it should take two arguments and return <, >, or == 0,
+ * depending on whether its first argument is <, >, or == its second
+ * argument (like strcmp, e.g.). fdup is a function to call when a duplicate
+ * node is inserted. it should return 0, or -1 and its return value
+ * will be the return value from ldap_avl_insert in the case of a duplicate node.
+ * the function will be called with the original node's data as its first
+ * argument and with the incoming duplicate node's data as its second
+ * argument. this could be used, for example, to keep a count with each
+ * node.
+ *
+ * NOTE: this routine may malloc memory
+ */
+int
+ldap_avl_insert( Avlnode ** root, void *data, AVL_CMP fcmp, AVL_DUP fdup )
+{
+ Avlnode *t, *p, *s, *q, *r;
+ int a, cmp, ncmp;
+
+ if ( *root == NULL ) {
+ if (( r = (Avlnode *) ber_memalloc( sizeof( Avlnode ))) == NULL ) {
+ return( -1 );
+ }
+ r->avl_link[0] = r->avl_link[1] = NULL;
+ r->avl_data = data;
+ r->avl_bits[0] = r->avl_bits[1] = AVL_CHILD;
+ r->avl_bf = EH;
+ *root = r;
+
+ return( 0 );
+ }
+
+ t = NULL;
+ s = p = *root;
+
+ /* find insertion point */
+ while (1) {
+ cmp = fcmp( data, p->avl_data );
+ if ( cmp == 0 )
+ return (*fdup)( p->avl_data, data );
+
+ cmp = (cmp > 0);
+ q = p->avl_link[cmp];
+ if (q == NULL) {
+ /* insert */
+ if (( q = (Avlnode *) ber_memalloc( sizeof( Avlnode ))) == NULL ) {
+ return( -1 );
+ }
+ q->avl_link[0] = q->avl_link[1] = NULL;
+ q->avl_data = data;
+ q->avl_bits[0] = q->avl_bits[1] = AVL_CHILD;
+ q->avl_bf = EH;
+
+ p->avl_link[cmp] = q;
+ break;
+ } else if ( q->avl_bf ) {
+ t = p;
+ s = q;
+ }
+ p = q;
+ }
+
+ /* adjust balance factors */
+ cmp = fcmp( data, s->avl_data ) > 0;
+ r = p = s->avl_link[cmp];
+ a = avl_bfs[cmp];
+
+ while ( p != q ) {
+ cmp = fcmp( data, p->avl_data ) > 0;
+ p->avl_bf = avl_bfs[cmp];
+ p = p->avl_link[cmp];
+ }
+
+ /* checks and balances */
+
+ if ( s->avl_bf == EH ) {
+ s->avl_bf = a;
+ return 0;
+ } else if ( s->avl_bf == -a ) {
+ s->avl_bf = EH;
+ return 0;
+ } else if ( s->avl_bf == a ) {
+ cmp = (a > 0);
+ ncmp = !cmp;
+ if ( r->avl_bf == a ) {
+ /* single rotation */
+ p = r;
+ s->avl_link[cmp] = r->avl_link[ncmp];
+ r->avl_link[ncmp] = s;
+ s->avl_bf = 0;
+ r->avl_bf = 0;
+ } else if ( r->avl_bf == -a ) {
+ /* double rotation */
+ p = r->avl_link[ncmp];
+ r->avl_link[ncmp] = p->avl_link[cmp];
+ p->avl_link[cmp] = r;
+ s->avl_link[cmp] = p->avl_link[ncmp];
+ p->avl_link[ncmp] = s;
+
+ if ( p->avl_bf == a ) {
+ s->avl_bf = -a;
+ r->avl_bf = 0;
+ } else if ( p->avl_bf == -a ) {
+ s->avl_bf = 0;
+ r->avl_bf = a;
+ } else {
+ s->avl_bf = 0;
+ r->avl_bf = 0;
+ }
+ p->avl_bf = 0;
+ }
+ /* Update parent */
+ if ( t == NULL )
+ *root = p;
+ else if ( s == t->avl_right )
+ t->avl_right = p;
+ else
+ t->avl_left = p;
+ }
+
+ return 0;
+}
+
+void*
+ldap_avl_delete( Avlnode **root, void* data, AVL_CMP fcmp )
+{
+ Avlnode *p, *q, *r, *top;
+ int side, side_bf, shorter, nside;
+
+ /* parent stack */
+ Avlnode *pptr[MAX_TREE_DEPTH];
+ unsigned char pdir[MAX_TREE_DEPTH];
+ int depth = 0;
+
+ if ( *root == NULL )
+ return NULL;
+
+ p = *root;
+
+ while (1) {
+ side = fcmp( data, p->avl_data );
+ if ( !side )
+ break;
+ side = ( side > 0 );
+ pdir[depth] = side;
+ pptr[depth++] = p;
+
+ p = p->avl_link[side];
+ if ( p == NULL )
+ return p;
+ }
+ data = p->avl_data;
+
+ /* If this node has two children, swap so we are deleting a node with
+ * at most one child.
+ */
+ if ( p->avl_link[0] && p->avl_link[1] ) {
+
+ /* find the immediate predecessor <q> */
+ q = p->avl_link[0];
+ side = depth;
+ pdir[depth++] = 0;
+ while (q->avl_link[1]) {
+ pdir[depth] = 1;
+ pptr[depth++] = q;
+ q = q->avl_link[1];
+ }
+ /* swap links */
+ r = p->avl_link[0];
+ p->avl_link[0] = q->avl_link[0];
+ q->avl_link[0] = r;
+
+ q->avl_link[1] = p->avl_link[1];
+ p->avl_link[1] = NULL;
+
+ q->avl_bf = p->avl_bf;
+
+ /* fix stack positions: old parent of p points to q */
+ pptr[side] = q;
+ if ( side ) {
+ r = pptr[side-1];
+ r->avl_link[pdir[side-1]] = q;
+ } else {
+ *root = q;
+ }
+ /* new parent of p points to p */
+ if ( depth-side > 1 ) {
+ r = pptr[depth-1];
+ r->avl_link[1] = p;
+ } else {
+ q->avl_link[0] = p;
+ }
+ }
+
+ /* now <p> has at most one child, get it */
+ q = p->avl_link[0] ? p->avl_link[0] : p->avl_link[1];
+
+ ber_memfree( p );
+
+ if ( !depth ) {
+ *root = q;
+ return data;
+ }
+
+ /* set the child into p's parent */
+ depth--;
+ p = pptr[depth];
+ side = pdir[depth];
+ p->avl_link[side] = q;
+
+ top = NULL;
+ shorter = 1;
+
+ while ( shorter ) {
+ p = pptr[depth];
+ side = pdir[depth];
+ nside = !side;
+ side_bf = avl_bfs[side];
+
+ /* case 1: height unchanged */
+ if ( p->avl_bf == EH ) {
+ /* Tree is now heavier on opposite side */
+ p->avl_bf = avl_bfs[nside];
+ shorter = 0;
+
+ } else if ( p->avl_bf == side_bf ) {
+ /* case 2: taller subtree shortened, height reduced */
+ p->avl_bf = EH;
+ } else {
+ /* case 3: shorter subtree shortened */
+ if ( depth )
+ top = pptr[depth-1]; /* p->parent; */
+ else
+ top = NULL;
+ /* set <q> to the taller of the two subtrees of <p> */
+ q = p->avl_link[nside];
+ if ( q->avl_bf == EH ) {
+ /* case 3a: height unchanged, single rotate */
+ p->avl_link[nside] = q->avl_link[side];
+ q->avl_link[side] = p;
+ shorter = 0;
+ q->avl_bf = side_bf;
+ p->avl_bf = (- side_bf);
+
+ } else if ( q->avl_bf == p->avl_bf ) {
+ /* case 3b: height reduced, single rotate */
+ p->avl_link[nside] = q->avl_link[side];
+ q->avl_link[side] = p;
+ shorter = 1;
+ q->avl_bf = EH;
+ p->avl_bf = EH;
+
+ } else {
+ /* case 3c: height reduced, balance factors opposite */
+ r = q->avl_link[side];
+ q->avl_link[side] = r->avl_link[nside];
+ r->avl_link[nside] = q;
+
+ p->avl_link[nside] = r->avl_link[side];
+ r->avl_link[side] = p;
+
+ if ( r->avl_bf == side_bf ) {
+ q->avl_bf = (- side_bf);
+ p->avl_bf = EH;
+ } else if ( r->avl_bf == (- side_bf)) {
+ q->avl_bf = EH;
+ p->avl_bf = side_bf;
+ } else {
+ q->avl_bf = EH;
+ p->avl_bf = EH;
+ }
+ r->avl_bf = EH;
+ q = r;
+ }
+ /* a rotation has caused <q> (or <r> in case 3c) to become
+ * the root. let <p>'s former parent know this.
+ */
+ if ( top == NULL ) {
+ *root = q;
+ } else if (top->avl_link[0] == p) {
+ top->avl_link[0] = q;
+ } else {
+ top->avl_link[1] = q;
+ }
+ /* end case 3 */
+ p = q;
+ }
+ if ( !depth )
+ break;
+ depth--;
+ } /* end while(shorter) */
+
+ return data;
+}
+
+static int
+avl_inapply( Avlnode *root, AVL_APPLY fn, void* arg, int stopflag )
+{
+ if ( root == 0 )
+ return( AVL_NOMORE );
+
+ if ( root->avl_left != 0 )
+ if ( avl_inapply( root->avl_left, fn, arg, stopflag )
+ == stopflag )
+ return( stopflag );
+
+ if ( (*fn)( root->avl_data, arg ) == stopflag )
+ return( stopflag );
+
+ if ( root->avl_right == 0 )
+ return( AVL_NOMORE );
+ else
+ return( avl_inapply( root->avl_right, fn, arg, stopflag ) );
+}
+
+static int
+avl_postapply( Avlnode *root, AVL_APPLY fn, void* arg, int stopflag )
+{
+ if ( root == 0 )
+ return( AVL_NOMORE );
+
+ if ( root->avl_left != 0 )
+ if ( avl_postapply( root->avl_left, fn, arg, stopflag )
+ == stopflag )
+ return( stopflag );
+
+ if ( root->avl_right != 0 )
+ if ( avl_postapply( root->avl_right, fn, arg, stopflag )
+ == stopflag )
+ return( stopflag );
+
+ return( (*fn)( root->avl_data, arg ) );
+}
+
+static int
+avl_preapply( Avlnode *root, AVL_APPLY fn, void* arg, int stopflag )
+{
+ if ( root == 0 )
+ return( AVL_NOMORE );
+
+ if ( (*fn)( root->avl_data, arg ) == stopflag )
+ return( stopflag );
+
+ if ( root->avl_left != 0 )
+ if ( avl_preapply( root->avl_left, fn, arg, stopflag )
+ == stopflag )
+ return( stopflag );
+
+ if ( root->avl_right == 0 )
+ return( AVL_NOMORE );
+ else
+ return( avl_preapply( root->avl_right, fn, arg, stopflag ) );
+}
+
+/*
+ * ldap_avl_apply -- avl tree root is traversed, function fn is called with
+ * arguments arg and the data portion of each node. if fn returns stopflag,
+ * the traversal is cut short, otherwise it continues. Do not use -6 as
+ * a stopflag, as this is what is used to indicate the traversal ran out
+ * of nodes.
+ */
+
+int
+ldap_avl_apply( Avlnode *root, AVL_APPLY fn, void* arg, int stopflag, int type )
+{
+ switch ( type ) {
+ case AVL_INORDER:
+ return( avl_inapply( root, fn, arg, stopflag ) );
+ case AVL_PREORDER:
+ return( avl_preapply( root, fn, arg, stopflag ) );
+ case AVL_POSTORDER:
+ return( avl_postapply( root, fn, arg, stopflag ) );
+ default:
+ fprintf( stderr, "Invalid traversal type %d\n", type );
+ return( -1 );
+ }
+
+ /* NOTREACHED */
+}
+
+/*
+ * ldap_avl_prefixapply - traverse avl tree root, applying function fprefix
+ * to any nodes that match. fcmp is called with data as its first arg
+ * and the current node's data as its second arg. it should return
+ * 0 if they match, < 0 if data is less, and > 0 if data is greater.
+ * the idea is to efficiently find all nodes that are prefixes of
+ * some key... Like ldap_avl_apply, this routine also takes a stopflag
+ * and will return prematurely if fmatch returns this value. Otherwise,
+ * AVL_NOMORE is returned.
+ */
+
+int
+ldap_avl_prefixapply(
+ Avlnode *root,
+ void* data,
+ AVL_CMP fmatch,
+ void* marg,
+ AVL_CMP fcmp,
+ void* carg,
+ int stopflag
+)
+{
+ int cmp;
+
+ if ( root == 0 )
+ return( AVL_NOMORE );
+
+ cmp = (*fcmp)( data, root->avl_data /* , carg */);
+ if ( cmp == 0 ) {
+ if ( (*fmatch)( root->avl_data, marg ) == stopflag )
+ return( stopflag );
+
+ if ( root->avl_left != 0 )
+ if ( ldap_avl_prefixapply( root->avl_left, data, fmatch,
+ marg, fcmp, carg, stopflag ) == stopflag )
+ return( stopflag );
+
+ if ( root->avl_right != 0 )
+ return( ldap_avl_prefixapply( root->avl_right, data, fmatch,
+ marg, fcmp, carg, stopflag ) );
+ else
+ return( AVL_NOMORE );
+
+ } else if ( cmp < 0 ) {
+ if ( root->avl_left != 0 )
+ return( ldap_avl_prefixapply( root->avl_left, data, fmatch,
+ marg, fcmp, carg, stopflag ) );
+ } else {
+ if ( root->avl_right != 0 )
+ return( ldap_avl_prefixapply( root->avl_right, data, fmatch,
+ marg, fcmp, carg, stopflag ) );
+ }
+
+ return( AVL_NOMORE );
+}
+
+/*
+ * ldap_avl_free -- traverse avltree root, freeing the memory it is using.
+ * the dfree() is called to free the data portion of each node. The
+ * number of items actually freed is returned.
+ */
+
+int
+ldap_avl_free( Avlnode *root, AVL_FREE dfree )
+{
+ int nleft, nright;
+
+ if ( root == 0 )
+ return( 0 );
+
+ nleft = nright = 0;
+ if ( root->avl_left != 0 )
+ nleft = ldap_avl_free( root->avl_left, dfree );
+
+ if ( root->avl_right != 0 )
+ nright = ldap_avl_free( root->avl_right, dfree );
+
+ if ( dfree )
+ (*dfree)( root->avl_data );
+ ber_memfree( root );
+
+ return( nleft + nright + 1 );
+}
+
+/*
+ * ldap_avl_find -- search avltree root for a node with data data. the function
+ * cmp is used to compare things. it is called with data as its first arg
+ * and the current node data as its second. it should return 0 if they match,
+ * < 0 if arg1 is less than arg2 and > 0 if arg1 is greater than arg2.
+ */
+
+Avlnode *
+ldap_avl_find2( Avlnode *root, const void *data, AVL_CMP fcmp )
+{
+ int cmp;
+
+ while ( root != 0 && (cmp = (*fcmp)( data, root->avl_data )) != 0 ) {
+ cmp = cmp > 0;
+ root = root->avl_link[cmp];
+ }
+ return root;
+}
+
+void*
+ldap_avl_find( Avlnode *root, const void* data, AVL_CMP fcmp )
+{
+ int cmp;
+
+ while ( root != 0 && (cmp = (*fcmp)( data, root->avl_data )) != 0 ) {
+ cmp = cmp > 0;
+ root = root->avl_link[cmp];
+ }
+
+ return( root ? root->avl_data : 0 );
+}
+
+/*
+ * ldap_avl_find_lin -- search avltree root linearly for a node with data data.
+ * the function cmp is used to compare things. it is called with data as its
+ * first arg and the current node data as its second. it should return 0 if
+ * they match, non-zero otherwise.
+ */
+
+void*
+ldap_avl_find_lin( Avlnode *root, const void* data, AVL_CMP fcmp )
+{
+ void* res;
+
+ if ( root == 0 )
+ return( NULL );
+
+ if ( (*fcmp)( data, root->avl_data ) == 0 )
+ return( root->avl_data );
+
+ if ( root->avl_left != 0 )
+ if ( (res = ldap_avl_find_lin( root->avl_left, data, fcmp ))
+ != NULL )
+ return( res );
+
+ if ( root->avl_right == 0 )
+ return( NULL );
+ else
+ return( ldap_avl_find_lin( root->avl_right, data, fcmp ) );
+}
+
+/* NON-REENTRANT INTERFACE */
+
+static void* *avl_list;
+static int avl_maxlist;
+static int ldap_avl_nextlist;
+
+#define AVL_GRABSIZE 100
+
+/* ARGSUSED */
+static int
+avl_buildlist( void* data, void* arg )
+{
+ static int slots;
+
+ if ( avl_list == (void* *) 0 ) {
+ avl_list = (void* *) ber_memalloc(AVL_GRABSIZE * sizeof(void*));
+ slots = AVL_GRABSIZE;
+ avl_maxlist = 0;
+ } else if ( avl_maxlist == slots ) {
+ slots += AVL_GRABSIZE;
+ avl_list = (void* *) ber_memrealloc( (char *) avl_list,
+ (unsigned) slots * sizeof(void*));
+ }
+
+ avl_list[ avl_maxlist++ ] = data;
+
+ return( 0 );
+}
+
+/*
+ * ldap_avl_getfirst() and ldap_avl_getnext() are provided as alternate tree
+ * traversal methods, to be used when a single function cannot be
+ * provided to be called with every node in the tree. ldap_avl_getfirst()
+ * traverses the tree and builds a linear list of all the nodes,
+ * returning the first node. ldap_avl_getnext() returns the next thing
+ * on the list built by ldap_avl_getfirst(). This means that ldap_avl_getfirst()
+ * can take a while, and that the tree should not be messed with while
+ * being traversed in this way, and that multiple traversals (even of
+ * different trees) cannot be active at once.
+ */
+
+void*
+ldap_avl_getfirst( Avlnode *root )
+{
+ if ( avl_list ) {
+ ber_memfree( (char *) avl_list);
+ avl_list = (void* *) 0;
+ }
+ avl_maxlist = 0;
+ ldap_avl_nextlist = 0;
+
+ if ( root == 0 )
+ return( 0 );
+
+ (void) ldap_avl_apply( root, avl_buildlist, (void*) 0, -1, AVL_INORDER );
+
+ return( avl_list[ ldap_avl_nextlist++ ] );
+}
+
+void*
+ldap_avl_getnext( void )
+{
+ if ( avl_list == 0 )
+ return( 0 );
+
+ if ( ldap_avl_nextlist == avl_maxlist ) {
+ ber_memfree( (void*) avl_list);
+ avl_list = (void* *) 0;
+ return( 0 );
+ }
+
+ return( avl_list[ ldap_avl_nextlist++ ] );
+}
+
+/* end non-reentrant code */
+
+
+int
+ldap_avl_dup_error( void* left, void* right )
+{
+ return( -1 );
+}
+
+int
+ldap_avl_dup_ok( void* left, void* right )
+{
+ return( 0 );
+}
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