text: /* dn2id.c - routines to deal with the dn2id index */
  /* $OpenLDAP$ */
  /* This work is part of OpenLDAP Software <http://www.openldap.org/>.
   *
   * Copyright 2000-2015 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>.
   */
  
  #include "portable.h"
  
  #include <stdio.h>
  #include <ac/string.h>
  
  #include "back-mdb.h"
  #include "idl.h"
  #include "lutil.h"
  
  /* Management routines for a hierarchically structured database.
   *
   * Instead of a ldbm-style dn2id database, we use a hierarchical one. Each
   * entry in this database is a struct diskNode, keyed by entryID and with
   * the data containing the RDN and entryID of the node's children. We use
   * a B-Tree with sorted duplicates to store all the children of a node under
   * the same key. Also, the first item under the key contains the entry's own
   * rdn and the ID of the node's parent, to allow bottom-up tree traversal as
   * well as top-down. To keep this info first in the list, the high bit of all
   * subsequent nrdnlen's is always set. This means we can only accomodate
   * RDNs up to length 32767, but that's fine since full DNs are already
   * restricted to 8192.
   *
   * Also each child node contains a count of the number of entries in
   * its subtree, appended after its entryID.
   *
   * The diskNode is a variable length structure. This definition is not
   * directly usable for in-memory manipulation.
   */
  typedef struct diskNode {
  	unsigned char nrdnlen[2];
  	char nrdn[1];
  	char rdn[1];                        /* variable placement */
  	unsigned char entryID[sizeof(ID)];  /* variable placement */
  	/* unsigned char nsubs[sizeof(ID)];	in child nodes only */
  } diskNode;
  
  /* Sort function for the sorted duplicate data items of a dn2id key.
   * Sorts based on normalized RDN, in length order.
   */
  int
  mdb_dup_compare(
  	const MDB_val *usrkey,
  	const MDB_val *curkey
  )
  {
  	diskNode *un, *cn;
  	int rc, nrlen;
  
  	un = (diskNode *)usrkey->mv_data;
  	cn = (diskNode *)curkey->mv_data;
  
  	/* data is not aligned, cannot compare directly */
  	rc = un->nrdnlen[0] - cn->nrdnlen[0];
  	if ( rc ) return rc;
  	rc = un->nrdnlen[1] - cn->nrdnlen[1];
  	if ( rc ) return rc;
  
  	nrlen = ((un->nrdnlen[0] & 0x7f) << 8) | un->nrdnlen[1];
  	return strncmp( un->nrdn, cn->nrdn, nrlen );
  }
  
  /* We add two elements to the DN2ID database - a data item under the parent's
   * entryID containing the child's RDN and entryID, and an item under the
   * child's entryID containing the parent's entryID.
   */
  int
  mdb_dn2id_add(
  	Operation	*op,
  	MDB_cursor	*mcp,
  	MDB_cursor	*mcd,
  	ID pid,
  	ID nsubs,
  	int upsub,
  	Entry		*e )
  {
  	struct mdb_info *mdb = (struct mdb_info *) op->o_bd->be_private;
  	MDB_val		key, data;
  	ID		nid;
  	int		rc, rlen, nrlen;
  	diskNode *d;
  	char *ptr;
  
  	Debug( LDAP_DEBUG_TRACE, "=> mdb_dn2id_add 0x%lx: \"%s\"\n",
  		e->e_id, e->e_ndn ? e->e_ndn : "", 0 );
  
  	nrlen = dn_rdnlen( op->o_bd, &e->e_nname );
  	if (nrlen) {
  		rlen = dn_rdnlen( op->o_bd, &e->e_name );
  	} else {
  		nrlen = e->e_nname.bv_len;
  		rlen = e->e_name.bv_len;
  	}
  
  	d = op->o_tmpalloc(sizeof(diskNode) + rlen + nrlen + sizeof(ID), op->o_tmpmemctx);
  	d->nrdnlen[1] = nrlen & 0xff;
  	d->nrdnlen[0] = (nrlen >> 8) | 0x80;
  	ptr = lutil_strncopy( d->nrdn, e->e_nname.bv_val, nrlen );
  	*ptr++ = '\0';
  	ptr = lutil_strncopy( ptr, e->e_name.bv_val, rlen );
  	*ptr++ = '\0';
  	memcpy( ptr, &e->e_id, sizeof( ID ));
  	ptr += sizeof( ID );
  	memcpy( ptr, &nsubs, sizeof( ID ));
  
  	key.mv_size = sizeof(ID);
  	key.mv_data = &nid;
  
  	nid = pid;
  
  	/* Need to make dummy root node once. Subsequent attempts
  	 * will fail harmlessly.
  	 */
  	if ( pid == 0 ) {
  		diskNode dummy = {{0, 0}, "", "", ""};
  		data.mv_data = &dummy;
  		data.mv_size = sizeof(diskNode);
  
  		mdb_cursor_put( mcp, &key, &data, MDB_NODUPDATA );
  	}
  
  	data.mv_data = d;
  	data.mv_size = sizeof(diskNode) + rlen + nrlen + sizeof( ID );
  
  	/* Add our child node under parent's key */
  	rc = mdb_cursor_put( mcp, &key, &data, MDB_NODUPDATA );
  
  	/* Add our own node */
  	if (rc == 0) {
  		int flag = MDB_NODUPDATA;
  		nid = e->e_id;
  		/* drop subtree count */
  		data.mv_size -= sizeof( ID );
  		ptr -= sizeof( ID );
  		memcpy( ptr, &pid, sizeof( ID ));
  		d->nrdnlen[0] ^= 0x80;
  
  		if ((slapMode & SLAP_TOOL_MODE) || (e->e_id == mdb->mi_nextid))
  			flag |= MDB_APPEND;
  		rc = mdb_cursor_put( mcd, &key, &data, flag );
  	}
  	op->o_tmpfree( d, op->o_tmpmemctx );
  
  	/* Add our subtree count to all superiors */
  	if ( rc == 0 && upsub && pid ) {
  		ID subs;
  		nid = pid;
  		do {
  			/* Get parent's RDN */
  			rc = mdb_cursor_get( mcp, &key, &data, MDB_SET );
  			if ( !rc ) {
  				char *p2;
  				ptr = (char *)data.mv_data + data.mv_size - sizeof( ID );
  				memcpy( &nid, ptr, sizeof( ID ));
  				/* Get parent's node under grandparent */
  				d = data.mv_data;
  				rlen = ( d->nrdnlen[0] << 8 ) | d->nrdnlen[1];
  				p2 = op->o_tmpalloc( rlen + 2, op->o_tmpmemctx );
  				memcpy( p2, data.mv_data, rlen+2 );
  				*p2 ^= 0x80;
  				data.mv_data = p2;
  				rc = mdb_cursor_get( mcp, &key, &data, MDB_GET_BOTH );
  				op->o_tmpfree( p2, op->o_tmpmemctx );
  				if ( !rc ) {
  					/* Get parent's subtree count */
  					ptr = (char *)data.mv_data + data.mv_size - sizeof( ID );
  					memcpy( &subs, ptr, sizeof( ID ));
  					subs += nsubs;
  					p2 = op->o_tmpalloc( data.mv_size, op->o_tmpmemctx );
  					memcpy( p2, data.mv_data, data.mv_size - sizeof( ID ));
  					memcpy( p2+data.mv_size - sizeof( ID ), &subs, sizeof( ID ));
  					data.mv_data = p2;
  					rc = mdb_cursor_put( mcp, &key, &data, MDB_CURRENT );
  					op->o_tmpfree( p2, op->o_tmpmemctx );
  				}
  			}
  			if ( rc )
  				break;
  		} while ( nid );
  	}
  
  	Debug( LDAP_DEBUG_TRACE, "<= mdb_dn2id_add 0x%lx: %d\n", e->e_id, rc, 0 );
  
  	return rc;
  }
  
  /* mc must have been set by mdb_dn2id */
  int
  mdb_dn2id_delete(
  	Operation	*op,
  	MDB_cursor *mc,
  	ID id,
  	ID nsubs )
  {
  	ID nid;
  	char *ptr;
  	int rc;
  
  	Debug( LDAP_DEBUG_TRACE, "=> mdb_dn2id_delete 0x%lx\n",
  		id, 0, 0 );
  
  	/* Delete our ID from the parent's list */
  	rc = mdb_cursor_del( mc, 0 );
  
  	/* Delete our ID from the tree. With sorted duplicates, this
  	 * will leave any child nodes still hanging around. This is OK
  	 * for modrdn, which will add our info back in later.
  	 */
  	if ( rc == 0 ) {
  		MDB_val	key, data;
  		if ( nsubs ) {
  			mdb_cursor_get( mc, &key, NULL, MDB_GET_CURRENT );
  			memcpy( &nid, key.mv_data, sizeof( ID ));
  		}
  		key.mv_size = sizeof(ID);
  		key.mv_data = &id;
  		rc = mdb_cursor_get( mc, &key, &data, MDB_SET );
  		if ( rc == 0 )
  			rc = mdb_cursor_del( mc, 0 );
  	}
  
  	/* Delete our subtree count from all superiors */
  	if ( rc == 0 && nsubs && nid ) {
  		MDB_val key, data;
  		ID subs;
  		key.mv_data = &nid;
  		key.mv_size = sizeof( ID );
  		do {
  			rc = mdb_cursor_get( mc, &key, &data, MDB_SET );
  			if ( !rc ) {
  				char *p2;
  				diskNode *d;
  				int rlen;
  				ptr = (char *)data.mv_data + data.mv_size - sizeof( ID );
  				memcpy( &nid, ptr, sizeof( ID ));
  				/* Get parent's node under grandparent */
  				d = data.mv_data;
  				rlen = ( d->nrdnlen[0] << 8 ) | d->nrdnlen[1];
  				p2 = op->o_tmpalloc( rlen + 2, op->o_tmpmemctx );
  				memcpy( p2, data.mv_data, rlen+2 );
  				*p2 ^= 0x80;
  				data.mv_data = p2;
  				rc = mdb_cursor_get( mc, &key, &data, MDB_GET_BOTH );
  				op->o_tmpfree( p2, op->o_tmpmemctx );
  				if ( !rc ) {
  					/* Get parent's subtree count */
  					ptr = (char *)data.mv_data + data.mv_size - sizeof( ID );
  					memcpy( &subs, ptr, sizeof( ID ));
  					subs -= nsubs;
  					p2 = op->o_tmpalloc( data.mv_size, op->o_tmpmemctx );
  					memcpy( p2, data.mv_data, data.mv_size - sizeof( ID ));
  					memcpy( p2+data.mv_size - sizeof( ID ), &subs, sizeof( ID ));
  					data.mv_data = p2;
  					rc = mdb_cursor_put( mc, &key, &data, MDB_CURRENT );
  					op->o_tmpfree( p2, op->o_tmpmemctx );
  				}
  
  			}
  			if ( rc )
  				break;
  		} while ( nid );
  	}
  
  	Debug( LDAP_DEBUG_TRACE, "<= mdb_dn2id_delete 0x%lx: %d\n", id, rc, 0 );
  	return rc;
  }
  
  /* return last found ID in *id if no match
   * If mc is provided, it will be left pointing to the RDN's
   * record under the parent's ID. If nsubs is provided, return
   * the number of entries in this entry's subtree.
   */
  int
  mdb_dn2id(
  	Operation	*op,
  	MDB_txn *txn,
  	MDB_cursor	*mc,
  	struct berval	*in,
  	ID	*id,
  	ID	*nsubs,
  	struct berval	*matched,
  	struct berval	*nmatched )
  {
  	struct mdb_info *mdb = (struct mdb_info *) op->o_bd->be_private;
  	MDB_cursor *cursor;
  	MDB_dbi dbi = mdb->mi_dn2id;
  	MDB_val		key, data;
  	int		rc = 0, nrlen;
  	diskNode *d;
  	char	*ptr;
  	char dn[SLAP_LDAPDN_MAXLEN];
  	ID pid, nid;
  	struct berval tmp;
  
  	Debug( LDAP_DEBUG_TRACE, "=> mdb_dn2id(\"%s\")\n", in->bv_val ? in->bv_val : "", 0, 0 );
  
  	if ( matched ) {
  		matched->bv_val = dn + sizeof(dn) - 1;
  		matched->bv_len = 0;
  		*matched->bv_val-- = '\0';
  	}
  	if ( nmatched ) {
  		nmatched->bv_len = 0;
  		nmatched->bv_val = 0;
  	}
  
  	if ( !in->bv_len ) {
  		*id = 0;
  		nid = 0;
  		goto done;
  	}
  
  	tmp = *in;
  
  	if ( op->o_bd->be_nsuffix[0].bv_len ) {
  		nrlen = tmp.bv_len - op->o_bd->be_nsuffix[0].bv_len;
  		tmp.bv_val += nrlen;
  		tmp.bv_len = op->o_bd->be_nsuffix[0].bv_len;
  	} else {
  		for ( ptr = tmp.bv_val + tmp.bv_len - 1; ptr >= tmp.bv_val; ptr-- )
  			if (DN_SEPARATOR(*ptr))
  				break;
  		ptr++;
  		tmp.bv_len -= ptr - tmp.bv_val;
  		tmp.bv_val = ptr;
  	}
  	nid = 0;
  	key.mv_size = sizeof(ID);
  
  	if ( mc ) {
  		cursor = mc;
  	} else {
  		rc = mdb_cursor_open( txn, dbi, &cursor );
  		if ( rc ) goto done;
  	}
  
  	for (;;) {
  		key.mv_data = &pid;
  		pid = nid;
  
  		data.mv_size = sizeof(diskNode) + tmp.bv_len;
  		d = op->o_tmpalloc( data.mv_size, op->o_tmpmemctx );
  		d->nrdnlen[1] = tmp.bv_len & 0xff;
  		d->nrdnlen[0] = (tmp.bv_len >> 8) | 0x80;
  		ptr = lutil_strncopy( d->nrdn, tmp.bv_val, tmp.bv_len );
  		*ptr = '\0';
  		data.mv_data = d;
  		rc = mdb_cursor_get( cursor, &key, &data, MDB_GET_BOTH );
  		op->o_tmpfree( d, op->o_tmpmemctx );
  		if ( rc )
  			break;
  		ptr = (char *) data.mv_data + data.mv_size - 2*sizeof(ID);
  		memcpy( &nid, ptr, sizeof(ID));
  
  		/* grab the non-normalized RDN */
  		if ( matched ) {
  			int rlen;
  			d = data.mv_data;
  			rlen = data.mv_size - sizeof(diskNode) - tmp.bv_len - sizeof(ID);
  			matched->bv_len += rlen;
  			matched->bv_val -= rlen + 1;
  			ptr = lutil_strcopy( matched->bv_val, d->rdn + tmp.bv_len );
  			if ( pid ) {
  				*ptr = ',';
  				matched->bv_len++;
  			}
  		}
  		if ( nmatched ) {
  			nmatched->bv_val = tmp.bv_val;
  		}
  
  		if ( tmp.bv_val > in->bv_val ) {
  			for (ptr = tmp.bv_val - 2; ptr > in->bv_val &&
  				!DN_SEPARATOR(*ptr); ptr--)	/* empty */;
  			if ( ptr >= in->bv_val ) {
  				if (DN_SEPARATOR(*ptr)) ptr++;
  				tmp.bv_len = tmp.bv_val - ptr - 1;
  				tmp.bv_val = ptr;
  			}
  		} else {
  			break;
  		}
  	}
  	*id = nid; 
  	/* return subtree count if requested */
  	if ( !rc && nsubs ) {
  		ptr = (char *)data.mv_data + data.mv_size - sizeof(ID);
  		memcpy( nsubs, ptr, sizeof( ID ));
  	}
  	if ( !mc )
  		mdb_cursor_close( cursor );
  done:
  	if ( matched ) {
  		if ( matched->bv_len ) {
  			ptr = op->o_tmpalloc( matched->bv_len+1, op->o_tmpmemctx );
  			strcpy( ptr, matched->bv_val );
  			matched->bv_val = ptr;
  		} else {
  			if ( BER_BVISEMPTY( &op->o_bd->be_nsuffix[0] ) && !nid ) {
  				ber_dupbv( matched, (struct berval *)&slap_empty_bv );
  			} else {
  				matched->bv_val = NULL;
  			}
  		}
  	}
  	if ( nmatched ) {
  		if ( nmatched->bv_val ) {
  			nmatched->bv_len = in->bv_len - (nmatched->bv_val - in->bv_val);
  		} else {
  			*nmatched = slap_empty_bv;
  		}
  	}
  
  	if( rc != 0 ) {
  		Debug( LDAP_DEBUG_TRACE, "<= mdb_dn2id: get failed: %s (%d)\n",
  			mdb_strerror( rc ), rc, 0 );
  	} else {
  		Debug( LDAP_DEBUG_TRACE, "<= mdb_dn2id: got id=0x%lx\n",
  			nid, 0, 0 );
  	}
  
  	return rc;
  }
  
  /* return IDs from root to parent of DN */
  int
  mdb_dn2sups(
  	Operation	*op,
  	MDB_txn *txn,
  	struct berval	*in,
  	ID	*ids )
  {
  	struct mdb_info *mdb = (struct mdb_info *) op->o_bd->be_private;
  	MDB_cursor *cursor;
  	MDB_dbi dbi = mdb->mi_dn2id;
  	MDB_val		key, data;
  	int		rc = 0, nrlen;
  	diskNode *d;
  	char	*ptr;
  	ID pid, nid;
  	struct berval tmp;
  
  	Debug( LDAP_DEBUG_TRACE, "=> mdb_dn2sups(\"%s\")\n", in->bv_val, 0, 0 );
  
  	if ( !in->bv_len ) {
  		goto done;
  	}
  
  	tmp = *in;
  
  	nrlen = tmp.bv_len - op->o_bd->be_nsuffix[0].bv_len;
  	tmp.bv_val += nrlen;
  	tmp.bv_len = op->o_bd->be_nsuffix[0].bv_len;
  	nid = 0;
  	key.mv_size = sizeof(ID);
  
  	rc = mdb_cursor_open( txn, dbi, &cursor );
  	if ( rc ) goto done;
  
  	for (;;) {
  		key.mv_data = &pid;
  		pid = nid;
  
  		data.mv_size = sizeof(diskNode) + tmp.bv_len;
  		d = op->o_tmpalloc( data.mv_size, op->o_tmpmemctx );
  		d->nrdnlen[1] = tmp.bv_len & 0xff;
  		d->nrdnlen[0] = (tmp.bv_len >> 8) | 0x80;
  		ptr = lutil_strncopy( d->nrdn, tmp.bv_val, tmp.bv_len );
  		*ptr = '\0';
  		data.mv_data = d;
  		rc = mdb_cursor_get( cursor, &key, &data, MDB_GET_BOTH );
  		op->o_tmpfree( d, op->o_tmpmemctx );
  		if ( rc ) {
  			mdb_cursor_close( cursor );
  			break;
  		}
  		ptr = (char *) data.mv_data + data.mv_size - 2*sizeof(ID);
  		memcpy( &nid, ptr, sizeof(ID));
  
  		if ( pid )
  			mdb_idl_insert( ids, pid );
  
  		if ( tmp.bv_val > in->bv_val ) {
  			for (ptr = tmp.bv_val - 2; ptr > in->bv_val &&
  				!DN_SEPARATOR(*ptr); ptr--)	/* empty */;
  			if ( ptr >= in->bv_val ) {
  				if (DN_SEPARATOR(*ptr)) ptr++;
  				tmp.bv_len = tmp.bv_val - ptr - 1;
  				tmp.bv_val = ptr;
  			}
  		} else {
  			break;
  		}
  	}
  
  done:
  	if( rc != 0 ) {
  		Debug( LDAP_DEBUG_TRACE, "<= mdb_dn2sups: get failed: %s (%d)\n",
  			mdb_strerror( rc ), rc, 0 );
  	}
  
  	return rc;
  }
  
  int
  mdb_dn2id_children(
  	Operation *op,
  	MDB_txn *txn,
  	Entry *e )
  {
  	struct mdb_info *mdb = (struct mdb_info *) op->o_bd->be_private;
  	MDB_dbi dbi = mdb->mi_dn2id;
  	MDB_val		key, data;
  	MDB_cursor	*cursor;
  	int		rc;
  	ID		id;
  
  	key.mv_size = sizeof(ID);
  	key.mv_data = &id;
  	id = e->e_id;
  
  	rc = mdb_cursor_open( txn, dbi, &cursor );
  	if ( rc ) return rc;
  
  	rc = mdb_cursor_get( cursor, &key, &data, MDB_SET );
  	if ( rc == 0 ) {
  		size_t dkids;
  		rc = mdb_cursor_count( cursor, &dkids );
  		if ( rc == 0 ) {
  			if ( dkids < 2 ) rc = MDB_NOTFOUND;
  		}
  	}
  	mdb_cursor_close( cursor );
  	return rc;
  }
  
  int
  mdb_id2name(
  	Operation *op,
  	MDB_txn *txn,
  	MDB_cursor **cursp,
  	ID id,
  	struct berval *name,
  	struct berval *nname )
  {
  	struct mdb_info *mdb = (struct mdb_info *) op->o_bd->be_private;
  	MDB_dbi dbi = mdb->mi_dn2id;
  	MDB_val		key, data;
  	MDB_cursor	*cursor;
  	int		rc, len, nlen;
  	char dn[SLAP_LDAPDN_MAXLEN], ndn[SLAP_LDAPDN_MAXLEN], *ptr;
  	char *dptr, *nptr;
  	diskNode *d;
  
  	key.mv_size = sizeof(ID);
  
  	if ( !*cursp ) {
  		rc = mdb_cursor_open( txn, dbi, cursp );
  		if ( rc ) return rc;
  	}
  	cursor = *cursp;
  
  	len = 0;
  	nlen = 0;
  	dptr = dn;
  	nptr = ndn;
  	while (id) {
  		unsigned int nrlen, rlen;
  		key.mv_data = &id;
  		data.mv_size = 0;
  		data.mv_data = "";
  		rc = mdb_cursor_get( cursor, &key, &data, MDB_SET );
  		if ( rc ) break;
  		ptr = data.mv_data;
  		ptr += data.mv_size - sizeof(ID);
  		memcpy( &id, ptr, sizeof(ID) );
  		d = data.mv_data;
  		nrlen = (d->nrdnlen[0] << 8) | d->nrdnlen[1];
  		rlen = data.mv_size - sizeof(diskNode) - nrlen;
  		assert( nrlen < 1024 && rlen < 1024 );	/* FIXME: Sanity check */
  		if (nptr > ndn) {
  			*nptr++ = ',';
  			*dptr++ = ',';
  		}
  		/* copy name and trailing NUL */
  		memcpy( nptr, d->nrdn, nrlen+1 );
  		memcpy( dptr, d->nrdn+nrlen+1, rlen+1 );
  		nptr += nrlen;
  		dptr += rlen;
  	}
  	if ( rc == 0 ) {
  		name->bv_len = dptr - dn;
  		nname->bv_len = nptr - ndn;
  		name->bv_val = op->o_tmpalloc( name->bv_len + 1, op->o_tmpmemctx );
  		nname->bv_val = op->o_tmpalloc( nname->bv_len + 1, op->o_tmpmemctx );
  		memcpy( name->bv_val, dn, name->bv_len );
  		name->bv_val[name->bv_len] = '\0';
  		memcpy( nname->bv_val, ndn, nname->bv_len );
  		nname->bv_val[nname->bv_len] = '\0';
  	}
  	return rc;
  }
  
  /* Find each id in ids that is a child of base and move it to res.
   */
  int
  mdb_idscope(
  	Operation *op,
  	MDB_txn *txn,
  	ID base,
  	ID *ids,
  	ID *res )
  {
  	struct mdb_info *mdb = (struct mdb_info *) op->o_bd->be_private;
  	MDB_dbi dbi = mdb->mi_dn2id;
  	MDB_val		key, data;
  	MDB_cursor	*cursor;
  	ID ida, id, cid = 0, ci0 = 0, idc = 0;
  	char	*ptr;
  	int		rc, copy;
  
  	key.mv_size = sizeof(ID);
  
  	MDB_IDL_ZERO( res );
  
  	rc = mdb_cursor_open( txn, dbi, &cursor );
  	if ( rc ) return rc;
  
  	ida = mdb_idl_first( ids, &cid );
  
  	/* Don't bother moving out of ids if it's a range */
  	if (!MDB_IDL_IS_RANGE(ids)) {
  		idc = ids[0];
  		ci0 = cid;
  	}
  
  	while (ida != NOID) {
  		copy = 1;
  		id = ida;
  		while (id) {
  			key.mv_data = &id;
  			rc = mdb_cursor_get( cursor, &key, &data, MDB_SET );
  			if ( rc ) {
  				/* not found, drop this from ids */
  				copy = 0;
  				break;
  			}
  			ptr = data.mv_data;
  			ptr += data.mv_size - sizeof(ID);
  			memcpy( &id, ptr, sizeof(ID) );
  			if ( id == base ) {
  				if ( res[0] >= MDB_IDL_DB_SIZE-1 ) {
  					/* too many aliases in scope. Fallback to range */
  					MDB_IDL_RANGE( res, MDB_IDL_FIRST( ids ), MDB_IDL_LAST( ids ));
  					goto leave;
  				}
  				res[0]++;
  				res[res[0]] = ida;
  				copy = 0;
  				break;
  			}
  			if ( op->ors_scope == LDAP_SCOPE_ONELEVEL )
  				break;
  		}
  		if (idc) {
  			if (copy) {
  				if (ci0 != cid)
  					ids[ci0] = ids[cid];
  				ci0++;
  			} else
  				idc--;
  		}
  		ida = mdb_idl_next( ids, &cid );
  	}
  	if (!MDB_IDL_IS_RANGE( ids ))
  		ids[0] = idc;
  
  leave:
  	mdb_cursor_close( cursor );
  	return rc;
  }
  
  /* See if base is a child of any of the scopes
   */
  int
  mdb_idscopes(
  	Operation *op,
  	IdScopes *isc )
  {
  	struct mdb_info *mdb = (struct mdb_info *) op->o_bd->be_private;
  	MDB_dbi dbi = mdb->mi_dn2id;
  	MDB_val		key, data;
  	ID id, prev;
  	ID2 id2;
  	char	*ptr;
  	int		rc = 0;
  	unsigned int x;
  	unsigned int nrlen, rlen;
  	diskNode *d;
  
  	key.mv_size = sizeof(ID);
  
  	if ( !isc->mc ) {
  		rc = mdb_cursor_open( isc->mt, dbi, &isc->mc );
  		if ( rc ) return rc;
  	}
  
  	id = isc->id;
  
  	/* Catch entries from deref'd aliases */
  	x = mdb_id2l_search( isc->scopes, id );
  	if ( x <= isc->scopes[0].mid && isc->scopes[x].mid == id ) {
  		isc->nscope = x;
  		return MDB_SUCCESS;
  	}
  
  	isc->sctmp[0].mid = 0;
  	while (id) {
  		if ( !rc ) {
  			key.mv_data = &id;
  			rc = mdb_cursor_get( isc->mc, &key, &data, MDB_SET );
  			if ( rc )
  				return rc;
  
  			/* save RDN info */
  		}
  		d = data.mv_data;
  		nrlen = (d->nrdnlen[0] << 8) | d->nrdnlen[1];
  		rlen = data.mv_size - sizeof(diskNode) - nrlen;
  		isc->nrdns[isc->numrdns].bv_len = nrlen;
  		isc->nrdns[isc->numrdns].bv_val = d->nrdn;
  		isc->rdns[isc->numrdns].bv_len = rlen;
  		isc->rdns[isc->numrdns].bv_val = d->nrdn+nrlen+1;
  		isc->numrdns++;
  
  		if (!rc && id != isc->id) {
  			/* remember our chain of parents */
  			id2.mid = id;
  			id2.mval = data;
  			mdb_id2l_insert( isc->sctmp, &id2 );
  		}
  		ptr = data.mv_data;
  		ptr += data.mv_size - sizeof(ID);
  		prev = id;
  		memcpy( &id, ptr, sizeof(ID) );
  		/* If we didn't advance, some parent is missing */
  		if ( id == prev )
  			return MDB_NOTFOUND;
  
  		x = mdb_id2l_search( isc->scopes, id );
  		if ( x <= isc->scopes[0].mid && isc->scopes[x].mid == id ) {
  			if ( !isc->scopes[x].mval.mv_data ) {
  				/* This node is in scope, add parent chain to scope */
  				int i;
  				for ( i = 1; i <= isc->sctmp[0].mid; i++ ) {
  					rc = mdb_id2l_insert( isc->scopes, &isc->sctmp[i] );
  					if ( rc )
  						break;
  				}
  				/* check id again since inserts may have changed its position */
  				if ( isc->scopes[x].mid != id )
  					x = mdb_id2l_search( isc->scopes, id );
  				isc->nscope = x;
  				return MDB_SUCCESS;
  			}
  			data = isc->scopes[x].mval;
  			rc = 1;
  		}
  		if ( op->ors_scope == LDAP_SCOPE_ONELEVEL )
  			break;
  	}
  	return MDB_SUCCESS;
  }
  
  /* See if ID is a child of any of the scopes,
   * return MDB_KEYEXIST if so.
   */
  int
  mdb_idscopechk(
  	Operation *op,
  	IdScopes *isc )
  {
  	struct mdb_info *mdb = (struct mdb_info *) op->o_bd->be_private;
  	MDB_val		key, data;
  	ID id, prev;
  	char	*ptr;
  	int		rc = 0;
  	unsigned int x;
  
  	key.mv_size = sizeof(ID);
  
  	if ( !isc->mc ) {
  		rc = mdb_cursor_open( isc->mt, mdb->mi_dn2id, &isc->mc );
  		if ( rc ) return rc;
  	}
  
  	id = isc->id;
  
  	while (id) {
  		if ( !rc ) {
  			key.mv_data = &id;
  			rc = mdb_cursor_get( isc->mc, &key, &data, MDB_SET );
  			if ( rc )
  				return rc;
  		}
  
  		ptr = data.mv_data;
  		ptr += data.mv_size - sizeof(ID);
  		prev = id;
  		memcpy( &id, ptr, sizeof(ID) );
  		/* If we didn't advance, some parent is missing */
  		if ( id == prev )
  			return MDB_NOTFOUND;
  
  		x = mdb_id2l_search( isc->scopes, id );
  		if ( x <= isc->scopes[0].mid && isc->scopes[x].mid == id )
  			return MDB_KEYEXIST;
  	}
  	return MDB_SUCCESS;
  }
  
  int
  mdb_dn2id_walk(
  	Operation *op,
  	IdScopes *isc
  )
  {
  	MDB_val key, data;
  	diskNode *d;
  	char *ptr;
  	int rc, n;
  	ID nsubs;
  
  	if ( !isc->numrdns ) {
  		key.mv_data = &isc->id;
  		key.mv_size = sizeof(ID);
  		rc = mdb_cursor_get( isc->mc, &key, &data, MDB_SET );
  		isc->scopes[0].mid = isc->id;
  		isc->numrdns++;
  		isc->nscope = 0;
  		/* skip base if not a subtree walk */
  		if ( isc->oscope == LDAP_SCOPE_SUBTREE ||
  			isc->oscope == LDAP_SCOPE_BASE )
  			return rc;
  	}
  	if ( isc->oscope == LDAP_SCOPE_BASE )
  		return MDB_NOTFOUND;
  
  	for (;;) {
  		/* Get next sibling */
  		rc = mdb_cursor_get( isc->mc, &key, &data, MDB_NEXT_DUP );
  		if ( !rc ) {
  			ptr = (char *)data.mv_data + data.mv_size - 2*sizeof(ID);
  			d = data.mv_data;
  			memcpy( &isc->id, ptr, sizeof(ID));
  
  			/* If we're pushing down, see if there's any children to find */
  			if ( isc->nscope ) {
  				ptr += sizeof(ID);
  				memcpy( &nsubs, ptr, sizeof(ID));
  				/* No children, go to next sibling */
  				if ( nsubs < 2 )
  					continue;
  			}
  			n = isc->numrdns;
  			isc->scopes[n].mid = isc->id;
  			n--;
  			isc->nrdns[n].bv_len = ((d->nrdnlen[0] & 0x7f) << 8) | d->nrdnlen[1];
  			isc->nrdns[n].bv_val = d->nrdn;
  			isc->rdns[n].bv_val = d->nrdn+isc->nrdns[n].bv_len+1;
  			isc->rdns[n].bv_len = data.mv_size - sizeof(diskNode) - isc->nrdns[n].bv_len - sizeof(ID);
  			/* return this ID to caller */
  			if ( !isc->nscope )
  				break;
  
  			/* push down to child */
  			key.mv_data = &isc->id;
  			mdb_cursor_get( isc->mc, &key, &data, MDB_SET );
  			isc->nscope = 0;
  			isc->numrdns++;
  			continue;
  
  		} else if ( rc == MDB_NOTFOUND ) {
  			if ( !isc->nscope && isc->oscope != LDAP_SCOPE_ONELEVEL ) {
  				/* reset to first dup */
  				mdb_cursor_get( isc->mc, &key, NULL, MDB_GET_CURRENT );
  				mdb_cursor_get( isc->mc, &key, &data, MDB_SET );
  				isc->nscope = 1;
  				continue;
  			} else {
  				isc->numrdns--;
  				/* stack is empty? */
  				if ( !isc->numrdns )
  					break;
  				/* pop up to prev node */
  				n = isc->numrdns - 1;
  				key.mv_data = &isc->scopes[n].mid;
  				key.mv_size = sizeof(ID);
  				data.mv_data = isc->nrdns[n].bv_val - 2;
  				data.mv_size = 1;	/* just needs to be non-zero, mdb_dup_compare doesn't care */
  				mdb_cursor_get( isc->mc, &key, &data, MDB_GET_BOTH );
  				continue;
  			}
  		} else {
  			break;
  		}
  	}
  	return rc;
  }
  
  /* restore the nrdn/rdn pointers after a txn reset */
  void mdb_dn2id_wrestore (
  	Operation *op,
  	IdScopes *isc
  )
  {
  	MDB_val key, data;
  	diskNode *d;
  	int rc, n, nrlen;
  	char *ptr;
  
  	/* We only need to restore up to the n-1th element,
  	 * the nth element will be replaced anyway
  	 */
  	key.mv_size = sizeof(ID);
  	for ( n=0; n<isc->numrdns-1; n++ ) {
  		key.mv_data = &isc->scopes[n+1].mid;
  		rc = mdb_cursor_get( isc->mc, &key, &data, MDB_SET );
  		if ( rc )
  			continue;
  		/* we can't use this data directly since its nrlen
  		 * is missing the high bit setting, so copy it and
  		 * set it properly. we just copy enough to satisfy
  		 * mdb_dup_compare.
  		 */
  		d = data.mv_data;
  		nrlen = ((d->nrdnlen[0] & 0x7f) << 8) | d->nrdnlen[1];
  		ptr = op->o_tmpalloc( nrlen+2, op->o_tmpmemctx );
  		memcpy( ptr, data.mv_data, nrlen+2 );
  		key.mv_data = &isc->scopes[n].mid;
  		data.mv_data = ptr;
  		data.mv_size = 1;
  		*ptr |= 0x80;
  		mdb_cursor_get( isc->mc, &key, &data, MDB_GET_BOTH );
  		op->o_tmpfree( ptr, op->o_tmpmemctx );
  
  		/* now we're back to where we wanted to be */
  		d = data.mv_data;
  		isc->nrdns[n].bv_val = d->nrdn;
  		isc->rdns[n].bv_val = d->nrdn+isc->nrdns[n].bv_len+1;
  	}
  }
  