text: /* $OpenLDAP$ */
  /* syncprov.c - syncrepl provider */
  /* This work is part of OpenLDAP Software <http://www.openldap.org/>.
   *
   * Copyright 2004-2022 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>.
   */
  /* ACKNOWLEDGEMENTS:
   * This work was initially developed by Howard Chu for inclusion in
   * OpenLDAP Software.
   */
  
  #include "portable.h"
  
  #ifdef SLAPD_OVER_SYNCPROV
  
  #include <ac/string.h>
  #include "lutil.h"
  #include "slap.h"
  #include "slap-config.h"
  #include "ldap_rq.h"
  
  #ifdef LDAP_DEVEL
  #define	CHECK_CSN	1
  #endif
  
  /* A modify request on a particular entry */
  typedef struct modinst {
  	struct modinst *mi_next;
  	Operation *mi_op;
  } modinst;
  
  typedef struct modtarget {
  	struct modinst *mt_mods;
  	struct modinst *mt_tail;
  	struct berval mt_dn;
  	ldap_pvt_thread_mutex_t mt_mutex;
  } modtarget;
  
  /* All the info of a psearch result that's shared between
   * multiple queues
   */
  typedef struct resinfo {
  	struct syncres *ri_list;
  	Entry *ri_e;
  	struct berval ri_dn;
  	struct berval ri_ndn;
  	struct berval ri_uuid;
  	struct berval ri_csn;
  	struct berval ri_cookie;
  	char ri_isref;
  	ldap_pvt_thread_mutex_t ri_mutex;
  } resinfo;
  
  /* A queued result of a persistent search */
  typedef struct syncres {
  	struct syncres *s_next;	/* list of results on this psearch queue */
  	struct syncres *s_rilist;	/* list of psearches using this result */
  	resinfo *s_info;
  	char s_mode;
  } syncres;
  
  /* Record of a persistent search */
  typedef struct syncops {
  	struct syncops *s_next;
  	struct syncprov_info_t *s_si;
  	struct berval	s_base;		/* ndn of search base */
  	ID		s_eid;		/* entryID of search base */
  	Operation	*s_op;		/* search op */
  	int		s_rid;
  	int		s_sid;
  	struct berval s_filterstr;
  	int		s_flags;	/* search status */
  #define	PS_IS_REFRESHING	0x01
  #define	PS_IS_DETACHED		0x02
  #define	PS_WROTE_BASE		0x04
  #define	PS_FIND_BASE		0x08
  #define	PS_FIX_FILTER		0x10
  #define	PS_TASK_QUEUED		0x20
  
  	int		s_inuse;	/* reference count */
  	struct syncres *s_res;
  	struct syncres *s_restail;
  	void *s_pool_cookie;
  	ldap_pvt_thread_mutex_t	s_mutex;
  } syncops;
  
  /* A received sync control */
  typedef struct sync_control {
  	struct sync_cookie sr_state;
  	int sr_rhint;
  } sync_control;
  
  #if 0 /* moved back to slap.h */
  #define	o_sync	o_ctrlflag[slap_cids.sc_LDAPsync]
  #endif
  /* o_sync_mode uses data bits of o_sync */
  #define	o_sync_mode	o_ctrlflag[slap_cids.sc_LDAPsync]
  
  #define SLAP_SYNC_NONE					(LDAP_SYNC_NONE<<SLAP_CONTROL_SHIFT)
  #define SLAP_SYNC_REFRESH				(LDAP_SYNC_REFRESH_ONLY<<SLAP_CONTROL_SHIFT)
  #define SLAP_SYNC_PERSIST				(LDAP_SYNC_RESERVED<<SLAP_CONTROL_SHIFT)
  #define SLAP_SYNC_REFRESH_AND_PERSIST	(LDAP_SYNC_REFRESH_AND_PERSIST<<SLAP_CONTROL_SHIFT)
  
  /* Record of which searches matched at premodify step */
  typedef struct syncmatches {
  	struct syncmatches *sm_next;
  	syncops *sm_op;
  } syncmatches;
  
  /* Session log data */
  typedef struct slog_entry {
  	struct berval se_uuid;
  	struct berval se_csn;
  	int	se_sid;
  	ber_tag_t	se_tag;
  } slog_entry;
  
  typedef struct sessionlog {
  	BerVarray	sl_mincsn;
  	int		*sl_sids;
  	int		sl_numcsns;
  	int		sl_num;
  	int		sl_size;
  	int		sl_playing;
  	TAvlnode *sl_entries;
  	ldap_pvt_thread_rdwr_t sl_mutex;
  } sessionlog;
  
  /* Accesslog callback data */
  typedef struct syncprov_accesslog_deletes {
  	Operation *op;
  	SlapReply *rs;
  	sync_control *srs;
  	BerVarray ctxcsn;
  	int numcsns, *sids;
  	Avlnode *uuids;
  	BerVarray uuid_list;
  	int ndel, list_len;
  	char *uuid_buf;
  } syncprov_accesslog_deletes;
  
  /* The main state for this overlay */
  typedef struct syncprov_info_t {
  	syncops		*si_ops;
  	struct berval	si_contextdn;
  	struct berval	si_logbase;
  	BerVarray	si_ctxcsn;	/* ldapsync context */
  	int		*si_sids;
  	int		si_numcsns;
  	int		si_chkops;	/* checkpointing info */
  	int		si_chktime;
  	int		si_numops;	/* number of ops since last checkpoint */
  	int		si_nopres;	/* Skip present phase */
  	int		si_usehint;	/* use reload hint */
  	int		si_active;	/* True if there are active mods */
  	int		si_dirty;	/* True if the context is dirty, i.e changes
  						 * have been made without updating the csn. */
  	time_t	si_chklast;	/* time of last checkpoint */
  	Avlnode	*si_mods;	/* entries being modified */
  	sessionlog	*si_logs;
  	ldap_pvt_thread_rdwr_t	si_csn_rwlock;
  	ldap_pvt_thread_mutex_t	si_ops_mutex;
  	ldap_pvt_thread_mutex_t	si_mods_mutex;
  	ldap_pvt_thread_mutex_t	si_resp_mutex;
  } syncprov_info_t;
  
  typedef struct opcookie {
  	slap_overinst *son;
  	syncmatches *smatches;
  	modtarget *smt;
  	Entry *se;
  	struct berval sdn;	/* DN of entry, for deletes */
  	struct berval sndn;
  	struct berval suuid;	/* UUID of entry */
  	struct berval sctxcsn;
  	short osid;	/* sid of op csn */
  	short rsid;	/* sid of relay */
  	short sreference;	/* Is the entry a reference? */
  	syncres ssres;
  } opcookie;
  
  typedef struct fbase_cookie {
  	struct berval *fdn;	/* DN of a modified entry, for scope testing */
  	syncops *fss;	/* persistent search we're testing against */
  	int fbase;	/* if TRUE we found the search base and it's still valid */
  	int fscope;	/* if TRUE then fdn is within the psearch scope */
  } fbase_cookie;
  
  static AttributeName csn_anlist[3];
  static AttributeName uuid_anlist[2];
  
  static AttributeDescription *ad_reqType, *ad_reqResult, *ad_reqDN,
  							*ad_reqEntryUUID, *ad_minCSN, *ad_reqNewDN;
  
  /* Build a LDAPsync intermediate state control */
  static int
  syncprov_state_ctrl(
  	Operation	*op,
  	SlapReply	*rs,
  	Entry		*e,
  	int		entry_sync_state,
  	LDAPControl	**ctrls,
  	int		num_ctrls,
  	int		send_cookie,
  	struct berval	*cookie )
  {
  	Attribute* a;
  	int ret;
  
  	BerElementBuffer berbuf;
  	BerElement *ber = (BerElement *)&berbuf;
  	LDAPControl *cp;
  	struct berval bv;
  	struct berval	entryuuid_bv = BER_BVNULL;
  
  	ber_init2( ber, 0, LBER_USE_DER );
  	ber_set_option( ber, LBER_OPT_BER_MEMCTX, &op->o_tmpmemctx );
  
  	for ( a = e->e_attrs; a != NULL; a = a->a_next ) {
  		AttributeDescription *desc = a->a_desc;
  		if ( desc == slap_schema.si_ad_entryUUID ) {
  			entryuuid_bv = a->a_nvals[0];
  			break;
  		}
  	}
  
  	/* FIXME: what if entryuuid is NULL or empty ? */
  
  	if ( send_cookie && cookie ) {
  		ber_printf( ber, "{eOON}",
  			entry_sync_state, &entryuuid_bv, cookie );
  	} else {
  		ber_printf( ber, "{eON}",
  			entry_sync_state, &entryuuid_bv );
  	}
  
  	ret = ber_flatten2( ber, &bv, 0 );
  	if ( ret == 0 ) {
  		cp = op->o_tmpalloc( sizeof( LDAPControl ) + bv.bv_len, op->o_tmpmemctx );
  		cp->ldctl_oid = LDAP_CONTROL_SYNC_STATE;
  		cp->ldctl_iscritical = (op->o_sync == SLAP_CONTROL_CRITICAL);
  		cp->ldctl_value.bv_val = (char *)&cp[1];
  		cp->ldctl_value.bv_len = bv.bv_len;
  		AC_MEMCPY( cp->ldctl_value.bv_val, bv.bv_val, bv.bv_len );
  		ctrls[num_ctrls] = cp;
  	}
  	ber_free_buf( ber );
  
  	if ( ret < 0 ) {
  		Debug( LDAP_DEBUG_TRACE,
  			"slap_build_sync_ctrl: ber_flatten2 failed (%d)\n",
  			ret );
  		send_ldap_error( op, rs, LDAP_OTHER, "internal error" );
  		return LDAP_OTHER;
  	}
  
  	return LDAP_SUCCESS;
  }
  
  /* Build a LDAPsync final state control */
  static int
  syncprov_done_ctrl(
  	Operation	*op,
  	SlapReply	*rs,
  	LDAPControl	**ctrls,
  	int			num_ctrls,
  	int			send_cookie,
  	struct berval *cookie,
  	int			refreshDeletes )
  {
  	int ret;
  	BerElementBuffer berbuf;
  	BerElement *ber = (BerElement *)&berbuf;
  	LDAPControl *cp;
  	struct berval bv;
  
  	ber_init2( ber, NULL, LBER_USE_DER );
  	ber_set_option( ber, LBER_OPT_BER_MEMCTX, &op->o_tmpmemctx );
  
  	ber_printf( ber, "{" );
  	if ( send_cookie && cookie ) {
  		ber_printf( ber, "O", cookie );
  	}
  	if ( refreshDeletes == LDAP_SYNC_REFRESH_DELETES ) {
  		ber_printf( ber, "b", refreshDeletes );
  	}
  	ber_printf( ber, "N}" );
  
  	ret = ber_flatten2( ber, &bv, 0 );
  	if ( ret == 0 ) {
  		cp = op->o_tmpalloc( sizeof( LDAPControl ) + bv.bv_len, op->o_tmpmemctx );
  		cp->ldctl_oid = LDAP_CONTROL_SYNC_DONE;
  		cp->ldctl_iscritical = (op->o_sync == SLAP_CONTROL_CRITICAL);
  		cp->ldctl_value.bv_val = (char *)&cp[1];
  		cp->ldctl_value.bv_len = bv.bv_len;
  		AC_MEMCPY( cp->ldctl_value.bv_val, bv.bv_val, bv.bv_len );
  		ctrls[num_ctrls] = cp;
  	}
  
  	ber_free_buf( ber );
  
  	if ( ret < 0 ) {
  		Debug( LDAP_DEBUG_TRACE,
  			"syncprov_done_ctrl: ber_flatten2 failed (%d)\n",
  			ret );
  		send_ldap_error( op, rs, LDAP_OTHER, "internal error" );
  		return LDAP_OTHER;
  	}
  
  	return LDAP_SUCCESS;
  }
  
  static int
  syncprov_sendinfo(
  	Operation	*op,
  	SlapReply	*rs,
  	int			type,
  	struct berval *cookie,
  	int			refreshDone,
  	BerVarray	syncUUIDs,
  	int			refreshDeletes )
  {
  	BerElementBuffer berbuf;
  	BerElement *ber = (BerElement *)&berbuf;
  	struct berval rspdata;
  
  	int ret;
  
  	ber_init2( ber, NULL, LBER_USE_DER );
  	ber_set_option( ber, LBER_OPT_BER_MEMCTX, &op->o_tmpmemctx );
  
  	if ( type ) {
  		switch ( type ) {
  		case LDAP_TAG_SYNC_NEW_COOKIE:
  			Debug( LDAP_DEBUG_SYNC, "%s syncprov_sendinfo: "
  				"sending a new cookie=%s\n",
  				op->o_log_prefix, cookie->bv_val );
  			ber_printf( ber, "tO", type, cookie );
  			break;
  		case LDAP_TAG_SYNC_REFRESH_DELETE:
  		case LDAP_TAG_SYNC_REFRESH_PRESENT:
  			Debug( LDAP_DEBUG_SYNC, "%s syncprov_sendinfo: "
  				"%s cookie=%s\n",
  				op->o_log_prefix,
  				type == LDAP_TAG_SYNC_REFRESH_DELETE ? "refreshDelete" : "refreshPresent",
  				cookie ? cookie->bv_val : "" );
  			ber_printf( ber, "t{", type );
  			if ( cookie ) {
  				ber_printf( ber, "O", cookie );
  			}
  			if ( refreshDone == 0 ) {
  				ber_printf( ber, "b", refreshDone );
  			}
  			ber_printf( ber, "N}" );
  			break;
  		case LDAP_TAG_SYNC_ID_SET:
  			Debug( LDAP_DEBUG_SYNC, "%s syncprov_sendinfo: "
  				"%s syncIdSet cookie=%s\n",
  				op->o_log_prefix, refreshDeletes ? "delete" : "present",
  				cookie ? cookie->bv_val : "" );
  			ber_printf( ber, "t{", type );
  			if ( cookie ) {
  				ber_printf( ber, "O", cookie );
  			}
  			if ( refreshDeletes == 1 ) {
  				ber_printf( ber, "b", refreshDeletes );
  			}
  			ber_printf( ber, "[W]", syncUUIDs );
  			ber_printf( ber, "N}" );
  			break;
  		default:
  			Debug( LDAP_DEBUG_TRACE,
  				"%s syncprov_sendinfo: invalid syncinfo type (%d)\n",
  				op->o_log_prefix, type );
  			return LDAP_OTHER;
  		}
  	}
  
  	ret = ber_flatten2( ber, &rspdata, 0 );
  
  	if ( ret < 0 ) {
  		Debug( LDAP_DEBUG_TRACE,
  			"syncprov_sendinfo: ber_flatten2 failed (%d)\n",
  			ret );
  		send_ldap_error( op, rs, LDAP_OTHER, "internal error" );
  		return LDAP_OTHER;
  	}
  
  	rs->sr_rspoid = LDAP_SYNC_INFO;
  	rs->sr_rspdata = &rspdata;
  	send_ldap_intermediate( op, rs );
  	rs->sr_rspdata = NULL;
  	ber_free_buf( ber );
  
  	return LDAP_SUCCESS;
  }
  
  /* Find a modtarget in an AVL tree */
  static int
  sp_avl_cmp( const void *c1, const void *c2 )
  {
  	const modtarget *m1, *m2;
  	int rc;
  
  	m1 = c1; m2 = c2;
  	rc = m1->mt_dn.bv_len - m2->mt_dn.bv_len;
  
  	if ( rc ) return rc;
  	return ber_bvcmp( &m1->mt_dn, &m2->mt_dn );
  }
  
  static int
  sp_uuid_cmp( const void *l, const void *r )
  {
  	const struct berval *left = l, *right = r;
  
  	return ber_bvcmp( left, right );
  }
  
  static int
  syncprov_sessionlog_cmp( const void *l, const void *r )
  {
  	const slog_entry *left = l, *right = r;
  	int ret = ber_bvcmp( &left->se_csn, &right->se_csn );
  	if ( !ret )
  		ret = ber_bvcmp( &left->se_uuid, &right->se_uuid );
  	/* Only time we have two modifications with same CSN is when we detect a
  	 * rename during replication.
  	 * We invert the test here because LDAP_REQ_MODDN is
  	 * numerically greater than LDAP_REQ_MODIFY but we
  	 * want it to occur first.
  	 */
  	if ( !ret )
  		ret = right->se_tag - left->se_tag;
  
  	return ret;
  }
  
  /* syncprov_findbase:
   *   finds the true DN of the base of a search (with alias dereferencing) and
   * checks to make sure the base entry doesn't get replaced with a different
   * entry (e.g., swapping trees via ModDN, or retargeting an alias). If a
   * change is detected, any persistent search on this base must be terminated /
   * reloaded.
   *   On the first call, we just save the DN and entryID. On subsequent calls
   * we compare the DN and entryID with the saved values.
   */
  static int
  findbase_cb( Operation *op, SlapReply *rs )
  {
  	slap_callback *sc = op->o_callback;
  
  	if ( rs->sr_type == REP_SEARCH && rs->sr_err == LDAP_SUCCESS ) {
  		fbase_cookie *fc = sc->sc_private;
  
  		/* If no entryID, we're looking for the first time.
  		 * Just store whatever we got.
  		 */
  		if ( fc->fss->s_eid == NOID ) {
  			fc->fbase = 2;
  			fc->fss->s_eid = rs->sr_entry->e_id;
  			ber_dupbv( &fc->fss->s_base, &rs->sr_entry->e_nname );
  
  		} else if ( rs->sr_entry->e_id == fc->fss->s_eid &&
  			dn_match( &rs->sr_entry->e_nname, &fc->fss->s_base )) {
  
  		/* OK, the DN is the same and the entryID is the same. */
  			fc->fbase = 1;
  		}
  	}
  	if ( rs->sr_err != LDAP_SUCCESS ) {
  		Debug( LDAP_DEBUG_ANY, "findbase failed! %d\n", rs->sr_err );
  	}
  	return LDAP_SUCCESS;
  }
  
  static Filter generic_filter = { LDAP_FILTER_PRESENT, { 0 }, NULL };
  static struct berval generic_filterstr = BER_BVC("(objectclass=*)");
  
  static int
  syncprov_findbase( Operation *op, fbase_cookie *fc )
  {
  	/* Use basic parameters from syncrepl search, but use
  	 * current op's threadctx / tmpmemctx
  	 */
  	ldap_pvt_thread_mutex_lock( &fc->fss->s_mutex );
  	if ( fc->fss->s_flags & PS_FIND_BASE ) {
  		slap_callback cb = {0};
  		Operation fop;
  		SlapReply frs = { REP_RESULT };
  		int rc;
  
  		fc->fss->s_flags ^= PS_FIND_BASE;
  		ldap_pvt_thread_mutex_unlock( &fc->fss->s_mutex );
  
  		fop = *fc->fss->s_op;
  
  		fop.o_bd = fop.o_bd->bd_self;
  		fop.o_hdr = op->o_hdr;
  		fop.o_time = op->o_time;
  		fop.o_tincr = op->o_tincr;
  		fop.o_extra = op->o_extra;
  
  		cb.sc_response = findbase_cb;
  		cb.sc_private = fc;
  
  		fop.o_sync_mode = 0;	/* turn off sync mode */
  		fop.o_dont_replicate = 1;
  		fop.o_managedsait = SLAP_CONTROL_CRITICAL;
  		fop.o_callback = &cb;
  		fop.o_tag = LDAP_REQ_SEARCH;
  		fop.ors_scope = LDAP_SCOPE_BASE;
  		fop.ors_limit = NULL;
  		fop.ors_slimit = 1;
  		fop.ors_tlimit = SLAP_NO_LIMIT;
  		fop.ors_attrs = slap_anlist_no_attrs;
  		fop.ors_attrsonly = 1;
  		fop.ors_filter = &generic_filter;
  		fop.ors_filterstr = generic_filterstr;
  
  		Debug( LDAP_DEBUG_SYNC, "%s syncprov_findbase: searching\n", op->o_log_prefix );
  		rc = fop.o_bd->be_search( &fop, &frs );
  	} else {
  		ldap_pvt_thread_mutex_unlock( &fc->fss->s_mutex );
  		fc->fbase = 1;
  	}
  
  	/* After the first call, see if the fdn resides in the scope */
  	if ( fc->fbase == 1 ) {
  		switch ( fc->fss->s_op->ors_scope ) {
  		case LDAP_SCOPE_BASE:
  			fc->fscope = dn_match( fc->fdn, &fc->fss->s_base );
  			break;
  		case LDAP_SCOPE_ONELEVEL: {
  			struct berval pdn;
  			dnParent( fc->fdn, &pdn );
  			fc->fscope = dn_match( &pdn, &fc->fss->s_base );
  			break; }
  		case LDAP_SCOPE_SUBTREE:
  			fc->fscope = dnIsSuffix( fc->fdn, &fc->fss->s_base );
  			break;
  		case LDAP_SCOPE_SUBORDINATE:
  			fc->fscope = dnIsSuffix( fc->fdn, &fc->fss->s_base ) &&
  				!dn_match( fc->fdn, &fc->fss->s_base );
  			break;
  		}
  	}
  
  	if ( fc->fbase )
  		return LDAP_SUCCESS;
  
  	/* If entryID has changed, then the base of this search has
  	 * changed. Invalidate the psearch.
  	 */
  	return LDAP_NO_SUCH_OBJECT;
  }
  
  /* syncprov_findcsn:
   *   This function has three different purposes, but they all use a search
   * that filters on entryCSN so they're combined here.
   * 1: at startup time, after a contextCSN has been read from the database,
   * we search for all entries with CSN >= contextCSN in case the contextCSN
   * was not checkpointed at the previous shutdown.
   *
   * 2: when the current contextCSN is known and we have a sync cookie, we search
   * for one entry with CSN = the cookie CSN. If not found, try <= cookie CSN.
   * If an entry is found, the cookie CSN is valid, otherwise it is stale.
   *
   * 3: during a refresh phase, we search for all entries with CSN <= the cookie
   * CSN, and generate Present records for them. We always collect this result
   * in SyncID sets, even if there's only one match.
   */
  typedef enum find_csn_t {
  	FIND_MAXCSN	= 1,
  	FIND_CSN	= 2,
  	FIND_PRESENT	= 3
  } find_csn_t;
  
  static int
  findmax_cb( Operation *op, SlapReply *rs )
  {
  	if ( rs->sr_type == REP_SEARCH && rs->sr_err == LDAP_SUCCESS ) {
  		struct berval *maxcsn = op->o_callback->sc_private;
  		Attribute *a = attr_find( rs->sr_entry->e_attrs,
  			slap_schema.si_ad_entryCSN );
  
  		if ( a && ber_bvcmp( &a->a_vals[0], maxcsn ) > 0 &&
  			slap_parse_csn_sid( &a->a_vals[0] ) == slap_serverID ) {
  			maxcsn->bv_len = a->a_vals[0].bv_len;
  			strcpy( maxcsn->bv_val, a->a_vals[0].bv_val );
  		}
  	}
  	return LDAP_SUCCESS;
  }
  
  static int
  findcsn_cb( Operation *op, SlapReply *rs )
  {
  	slap_callback *sc = op->o_callback;
  
  	/* We just want to know that at least one exists, so it's OK if
  	 * we exceed the unchecked limit.
  	 */
  	if ( rs->sr_err == LDAP_ADMINLIMIT_EXCEEDED ||
  		(rs->sr_type == REP_SEARCH && rs->sr_err == LDAP_SUCCESS )) {
  		sc->sc_private = (void *)1;
  	}
  	return LDAP_SUCCESS;
  }
  
  /* Build a list of entryUUIDs for sending in a SyncID set */
  
  #define UUID_LEN	16
  
  typedef struct fpres_cookie {
  	int num;
  	BerVarray uuids;
  	char *last;
  } fpres_cookie;
  
  static int
  findpres_cb( Operation *op, SlapReply *rs )
  {
  	slap_callback *sc = op->o_callback;
  	fpres_cookie *pc = sc->sc_private;
  	Attribute *a;
  	int ret = SLAP_CB_CONTINUE;
  
  	switch ( rs->sr_type ) {
  	case REP_SEARCH:
  		a = attr_find( rs->sr_entry->e_attrs, slap_schema.si_ad_entryUUID );
  		if ( a ) {
  			pc->uuids[pc->num].bv_val = pc->last;
  			AC_MEMCPY( pc->uuids[pc->num].bv_val, a->a_nvals[0].bv_val,
  				pc->uuids[pc->num].bv_len );
  			pc->num++;
  			pc->last = pc->uuids[pc->num].bv_val;
  			pc->uuids[pc->num].bv_val = NULL;
  		}
  		ret = LDAP_SUCCESS;
  		if ( pc->num != SLAP_SYNCUUID_SET_SIZE )
  			break;
  		/* FALLTHRU */
  	case REP_RESULT:
  		ret = rs->sr_err;
  		if ( pc->num ) {
  			ret = syncprov_sendinfo( op, rs, LDAP_TAG_SYNC_ID_SET, NULL,
  				0, pc->uuids, 0 );
  			pc->uuids[pc->num].bv_val = pc->last;
  			pc->num = 0;
  			pc->last = pc->uuids[0].bv_val;
  		}
  		break;
  	default:
  		break;
  	}
  	return ret;
  }
  
  static int
  syncprov_findcsn( Operation *op, find_csn_t mode, struct berval *csn )
  {
  	slap_overinst		*on = (slap_overinst *)op->o_bd->bd_info;
  	syncprov_info_t		*si = on->on_bi.bi_private;
  
  	slap_callback cb = {0};
  	Operation fop;
  	SlapReply frs = { REP_RESULT };
  	char buf[LDAP_PVT_CSNSTR_BUFSIZE + STRLENOF("(entryCSN<=)")];
  	char cbuf[LDAP_PVT_CSNSTR_BUFSIZE];
  	struct berval maxcsn;
  	Filter cf;
  	AttributeAssertion eq = ATTRIBUTEASSERTION_INIT;
  	fpres_cookie pcookie;
  	sync_control *srs = NULL;
  	struct slap_limits_set fc_limits;
  	int i, rc = LDAP_SUCCESS, findcsn_retry = 1;
  	int maxid;
  
  	if ( mode != FIND_MAXCSN ) {
  		srs = op->o_controls[slap_cids.sc_LDAPsync];
  	}
  
  	Debug( LDAP_DEBUG_SYNC, "%s syncprov_findcsn: mode=%s csn=%s\n",
  		op->o_log_prefix,
  		mode == FIND_MAXCSN ?
  			"FIND_MAXCSN" :
  			mode == FIND_CSN ?
  				"FIND_CSN" :
  				"FIND_PRESENT",
  		csn ? csn->bv_val : "" );
  
  	fop = *op;
  	fop.o_sync_mode &= SLAP_CONTROL_MASK;	/* turn off sync_mode */
  	/* We want pure entries, not referrals */
  	fop.o_managedsait = SLAP_CONTROL_CRITICAL;
  	fop.o_dont_replicate = 1;
  
  	cf.f_ava = &eq;
  	cf.f_av_desc = slap_schema.si_ad_entryCSN;
  	BER_BVZERO( &cf.f_av_value );
  	cf.f_next = NULL;
  
  	fop.o_callback = &cb;
  	fop.ors_limit = NULL;
  	fop.ors_tlimit = SLAP_NO_LIMIT;
  	fop.ors_filter = &cf;
  	fop.ors_filterstr.bv_val = buf;
  
  again:
  	switch( mode ) {
  	case FIND_MAXCSN:
  		cf.f_choice = LDAP_FILTER_GE;
  		/* If there are multiple CSNs, use the one with our serverID */
  		for ( i=0; i<si->si_numcsns; i++) {
  			if ( slap_serverID == si->si_sids[i] ) {
  				maxid = i;
  				break;
  			}
  		}
  		if ( i == si->si_numcsns ) {
  			/* No match: this is multimaster, and none of the content in the DB
  			 * originated locally. Treat like no CSN.
  			 */
  			return LDAP_NO_SUCH_OBJECT;
  		}
  		cf.f_av_value = si->si_ctxcsn[maxid];
  		fop.ors_filterstr.bv_len = snprintf( buf, sizeof( buf ),
  			"(entryCSN>=%s)", cf.f_av_value.bv_val );
  		if ( fop.ors_filterstr.bv_len >= sizeof( buf ) ) {
  			return LDAP_OTHER;
  		}
  		fop.ors_attrsonly = 0;
  		fop.ors_attrs = csn_anlist;
  		fop.ors_slimit = SLAP_NO_LIMIT;
  		cb.sc_private = &maxcsn;
  		cb.sc_response = findmax_cb;
  		strcpy( cbuf, cf.f_av_value.bv_val );
  		maxcsn.bv_val = cbuf;
  		maxcsn.bv_len = cf.f_av_value.bv_len;
  		break;
  	case FIND_CSN:
  		if ( BER_BVISEMPTY( &cf.f_av_value )) {
  			cf.f_av_value = *csn;
  		}
  		fop.o_dn = op->o_bd->be_rootdn;
  		fop.o_ndn = op->o_bd->be_rootndn;
  		fop.o_req_dn = op->o_bd->be_suffix[0];
  		fop.o_req_ndn = op->o_bd->be_nsuffix[0];
  		/* Look for exact match the first time */
  		if ( findcsn_retry ) {
  			cf.f_choice = LDAP_FILTER_EQUALITY;
  			fop.ors_filterstr.bv_len = snprintf( buf, sizeof( buf ),
  				"(entryCSN=%s)", cf.f_av_value.bv_val );
  		/* On retry, look for <= */
  		} else {
  			cf.f_choice = LDAP_FILTER_LE;
  			fop.ors_limit = &fc_limits;
  			memset( &fc_limits, 0, sizeof( fc_limits ));
  			fc_limits.lms_s_unchecked = 1;
  			fop.ors_filterstr.bv_len = snprintf( buf, sizeof( buf ),
  				"(entryCSN<=%s)", cf.f_av_value.bv_val );
  		}
  		if ( fop.ors_filterstr.bv_len >= sizeof( buf ) ) {
  			return LDAP_OTHER;
  		}
  		fop.ors_attrsonly = 1;
  		fop.ors_attrs = slap_anlist_no_attrs;
  		fop.ors_slimit = 1;
  		cb.sc_private = NULL;
  		cb.sc_response = findcsn_cb;
  		break;
  	case FIND_PRESENT:
  		fop.ors_filter = op->ors_filter;
  		fop.ors_filterstr = op->ors_filterstr;
  		fop.ors_attrsonly = 0;
  		fop.ors_attrs = uuid_anlist;
  		fop.ors_slimit = SLAP_NO_LIMIT;
  		cb.sc_private = &pcookie;
  		cb.sc_response = findpres_cb;
  		pcookie.num = 0;
  
  		/* preallocate storage for a full set */
  		pcookie.uuids = op->o_tmpalloc( (SLAP_SYNCUUID_SET_SIZE+1) *
  			sizeof(struct berval) + SLAP_SYNCUUID_SET_SIZE * UUID_LEN,
  			op->o_tmpmemctx );
  		pcookie.last = (char *)(pcookie.uuids + SLAP_SYNCUUID_SET_SIZE+1);
  		pcookie.uuids[0].bv_val = pcookie.last;
  		pcookie.uuids[0].bv_len = UUID_LEN;
  		for (i=1; i<SLAP_SYNCUUID_SET_SIZE; i++) {
  			pcookie.uuids[i].bv_val = pcookie.uuids[i-1].bv_val + UUID_LEN;
  			pcookie.uuids[i].bv_len = UUID_LEN;
  		}
  		break;
  	}
  
  	fop.o_bd->bd_info = (BackendInfo *)on->on_info;
  	fop.o_bd->be_search( &fop, &frs );
  	fop.o_bd->bd_info = (BackendInfo *)on;
  
  	switch( mode ) {
  	case FIND_MAXCSN:
  		if ( ber_bvcmp( &si->si_ctxcsn[maxid], &maxcsn )) {
  #ifdef CHECK_CSN
  			Syntax *syn = slap_schema.si_ad_contextCSN->ad_type->sat_syntax;
  			assert( !syn->ssyn_validate( syn, &maxcsn ));
  #endif
  			ber_bvreplace( &si->si_ctxcsn[maxid], &maxcsn );
  			si->si_numops++;	/* ensure a checkpoint */
  		}
  		break;
  	case FIND_CSN:
  		/* If matching CSN was not found, invalidate the context. */
  		Debug( LDAP_DEBUG_SYNC, "%s syncprov_findcsn: csn%s=%s %sfound\n",
  			op->o_log_prefix,
  			cf.f_choice == LDAP_FILTER_EQUALITY ? "=" : "<",
  			cf.f_av_value.bv_val, cb.sc_private ? "" : "not " );
  		if ( !cb.sc_private ) {
  			/* If we didn't find an exact match, then try for <= */
  			if ( findcsn_retry ) {
  				findcsn_retry = 0;
  				rs_reinit( &frs, REP_RESULT );
  				goto again;
  			}
  			rc = LDAP_NO_SUCH_OBJECT;
  		}
  		break;
  	case FIND_PRESENT:
  		op->o_tmpfree( pcookie.uuids, op->o_tmpmemctx );
  		break;
  	}
  
  	return rc;
  }
  
  static void free_resinfo( syncres *sr )
  {
  	syncres **st;
  	resinfo *ri = sr->s_info;
  	int freeit = 0;
  
  	ldap_pvt_thread_mutex_lock( &ri->ri_mutex );
  	for (st = &sr->s_info->ri_list; *st; st = &(*st)->s_rilist) {
  		if (*st == sr) {
  			*st = sr->s_rilist;
  			if ( !sr->s_info->ri_list )
  				freeit = 1;
  			sr->s_info = NULL;
  			break;
  		}
  	}
  	ldap_pvt_thread_mutex_unlock( &ri->ri_mutex );
  	if ( freeit ) {
  		ldap_pvt_thread_mutex_destroy( &ri->ri_mutex );
  		if ( ri->ri_e )
  			entry_free( ri->ri_e );
  		if ( !BER_BVISNULL( &ri->ri_cookie ))
  			ch_free( ri->ri_cookie.bv_val );
  		ch_free( ri );
  	}
  }
  
  #define FS_UNLINK	1
  #define FS_LOCK		2
  
  static int
  syncprov_free_syncop( syncops *so, int flags )
  {
  	syncres *sr, *srnext;
  	GroupAssertion *ga, *gnext;
  
  	if ( flags & FS_LOCK )
  		ldap_pvt_thread_mutex_lock( &so->s_mutex );
  	/* already being freed, or still in use */
  	if ( !so->s_inuse || --so->s_inuse > 0 ) {
  		if ( flags & FS_LOCK )
  			ldap_pvt_thread_mutex_unlock( &so->s_mutex );
  		return 0;
  	}
  	ldap_pvt_thread_mutex_unlock( &so->s_mutex );
  	if (( flags & FS_UNLINK ) && so->s_si ) {
  		syncops **sop;
  		ldap_pvt_thread_mutex_lock( &so->s_si->si_ops_mutex );
  		for ( sop = &so->s_si->si_ops; *sop; sop = &(*sop)->s_next ) {
  			if ( *sop == so ) {
  				*sop = so->s_next;
  				break;
  			}
  		}
  		ldap_pvt_thread_mutex_unlock( &so->s_si->si_ops_mutex );
  	}
  	if ( so->s_flags & PS_IS_DETACHED ) {
  		filter_free( so->s_op->ors_filter );
  		for ( ga = so->s_op->o_groups; ga; ga=gnext ) {
  			gnext = ga->ga_next;
  			ch_free( ga );
  		}
  		ch_free( so->s_op );
  	}
  	ch_free( so->s_base.bv_val );
  	for ( sr=so->s_res; sr; sr=srnext ) {
  		srnext = sr->s_next;
  		free_resinfo( sr );
  		ch_free( sr );
  	}
  	ldap_pvt_thread_mutex_destroy( &so->s_mutex );
  	ch_free( so );
  	return 1;
  }
  
  /* Send a persistent search response */
  static int
  syncprov_sendresp( Operation *op, resinfo *ri, syncops *so, int mode )
  {
  	SlapReply rs = { REP_SEARCH };
  	struct berval cookie, csns[2];
  	Entry e_uuid = {0};
  	Attribute a_uuid = {0};
  
  	if ( so->s_op->o_abandon )
  		return SLAPD_ABANDON;
  
  	rs.sr_ctrls = op->o_tmpalloc( sizeof(LDAPControl *)*2, op->o_tmpmemctx );
  	rs.sr_ctrls[1] = NULL;
  	rs.sr_flags = REP_CTRLS_MUSTBEFREED;
  	csns[0] = ri->ri_csn;
  	BER_BVZERO( &csns[1] );
  	slap_compose_sync_cookie( op, &cookie, csns, so->s_rid,
  				 slap_serverID ? slap_serverID : -1, NULL );
  
  #ifdef LDAP_DEBUG
  	if ( so->s_sid > 0 ) {
  		Debug( LDAP_DEBUG_SYNC, "%s syncprov_sendresp: to=%03x, cookie=%s\n",
  			op->o_log_prefix, so->s_sid, cookie.bv_val );
  	} else {
  		Debug( LDAP_DEBUG_SYNC, "%s syncprov_sendresp: cookie=%s\n",
  			op->o_log_prefix, cookie.bv_val );
  	}
  #endif
  
  	e_uuid.e_attrs = &a_uuid;
  	a_uuid.a_desc = slap_schema.si_ad_entryUUID;
  	a_uuid.a_nvals = &ri->ri_uuid;
  	rs.sr_err = syncprov_state_ctrl( op, &rs, &e_uuid,
  		mode, rs.sr_ctrls, 0, 1, &cookie );
  	op->o_tmpfree( cookie.bv_val, op->o_tmpmemctx );
  
  	rs.sr_entry = &e_uuid;
  	if ( mode == LDAP_SYNC_ADD || mode == LDAP_SYNC_MODIFY ) {
  		e_uuid = *ri->ri_e;
  		e_uuid.e_private = NULL;
  	}
  
  	switch( mode ) {
  	case LDAP_SYNC_ADD:
  		if ( ri->ri_isref && so->s_op->o_managedsait <= SLAP_CONTROL_IGNORED ) {
  			rs.sr_ref = get_entry_referrals( op, rs.sr_entry );
  			rs.sr_err = send_search_reference( op, &rs );
  			ber_bvarray_free( rs.sr_ref );
  			break;
  		}
  		/* fallthru */
  	case LDAP_SYNC_MODIFY:
  		Debug( LDAP_DEBUG_SYNC, "%s syncprov_sendresp: sending %s, dn=%s\n",
  			op->o_log_prefix,
  			mode == LDAP_SYNC_ADD ? "LDAP_SYNC_ADD" : "LDAP_SYNC_MODIFY",
  			e_uuid.e_nname.bv_val );
  		rs.sr_attrs = op->ors_attrs;
  		rs.sr_err = send_search_entry( op, &rs );
  		break;
  	case LDAP_SYNC_DELETE:
  		Debug( LDAP_DEBUG_SYNC, "%s syncprov_sendresp: "
  			"sending LDAP_SYNC_DELETE, dn=%s\n",
  			op->o_log_prefix, ri->ri_dn.bv_val );
  		e_uuid.e_attrs = NULL;
  		e_uuid.e_name = ri->ri_dn;
  		e_uuid.e_nname = ri->ri_ndn;
  		if ( ri->ri_isref && so->s_op->o_managedsait <= SLAP_CONTROL_IGNORED ) {
  			struct berval bv = BER_BVNULL;
  			rs.sr_ref = &bv;
  			rs.sr_err = send_search_reference( op, &rs );
  		} else {
  			rs.sr_err = send_search_entry( op, &rs );
  		}
  		break;
  	default:
  		assert(0);
  	}
  	return rs.sr_err;
  }
  
  static void
  syncprov_qstart( syncops *so );
  
  /* Play back queued responses */
  static int
  syncprov_qplay( Operation *op, syncops *so )
  {
  	syncres *sr;
  	int rc = 0;
  
  	do {
  		ldap_pvt_thread_mutex_lock( &so->s_mutex );
  		sr = so->s_res;
  		/* Exit loop with mutex held */
  		if ( !sr )
  			break;
  		so->s_res = sr->s_next;
  		if ( !so->s_res )
  			so->s_restail = NULL;
  		ldap_pvt_thread_mutex_unlock( &so->s_mutex );
  
  		if ( !so->s_op->o_abandon ) {
  
  			if ( sr->s_mode == LDAP_SYNC_NEW_COOKIE ) {
  				SlapReply rs = { REP_INTERMEDIATE };
  
  				rc = syncprov_sendinfo( op, &rs, LDAP_TAG_SYNC_NEW_COOKIE,
  					&sr->s_info->ri_cookie, 0, NULL, 0 );
  			} else {
  				rc = syncprov_sendresp( op, sr->s_info, so, sr->s_mode );
  			}
  		}
  
  		free_resinfo( sr );
  		ch_free( sr );
  
  		if ( so->s_op->o_abandon )
  			continue;
  
  		/* Exit loop with mutex held */
  		ldap_pvt_thread_mutex_lock( &so->s_mutex );
  		break;
  
  	} while (1);
  
  	/* We now only send one change at a time, to prevent one
  	 * psearch from hogging all the CPU. Resubmit this task if
  	 * there are more responses queued and no errors occurred.
  	 */
  
  	if ( rc == 0 && so->s_res ) {
  		syncprov_qstart( so );
  	}
  
  	return rc;
  }
  
  /* task for playing back queued responses */
  static void *
  syncprov_qtask( void *ctx, void *arg )
  {
  	syncops *so = arg;
  	OperationBuffer opbuf;
  	Operation *op;
  	BackendDB be;
  	int rc;
  
  	op = &opbuf.ob_op;
  	*op = *so->s_op;
  	op->o_hdr = &opbuf.ob_hdr;
  	op->o_controls = opbuf.ob_controls;
  	memset( op->o_controls, 0, sizeof(opbuf.ob_controls) );
  	op->o_sync = SLAP_CONTROL_IGNORED;
  
  	*op->o_hdr = *so->s_op->o_hdr;
  
  	op->o_tmpmemctx = slap_sl_mem_create(SLAP_SLAB_SIZE, SLAP_SLAB_STACK, ctx, 1);
  	op->o_tmpmfuncs = &slap_sl_mfuncs;
  	op->o_threadctx = ctx;
  	operation_counter_init( op, ctx );
  
  	/* syncprov_qplay expects a fake db */
  	be = *so->s_op->o_bd;
  	be.be_flags |= SLAP_DBFLAG_OVERLAY;
  	op->o_bd = &be;
  	LDAP_SLIST_FIRST(&op->o_extra) = NULL;
  	op->o_callback = NULL;
  
  	rc = syncprov_qplay( op, so );
  
  	/* if an error occurred, or no responses left, task is no longer queued */
  	if ( !rc && !so->s_res )
  		rc = 1;
  
  	/* decrement use count... */
  	if ( !syncprov_free_syncop( so, FS_UNLINK )) {
  		if ( rc )
  			/* if we didn't unlink, and task is no longer queued, clear flag */
  			so->s_flags ^= PS_TASK_QUEUED;
  		ldap_pvt_thread_mutex_unlock( &so->s_mutex );
  	}
  
  	return NULL;
  }
  
  /* Start the task to play back queued psearch responses */
  static void
  syncprov_qstart( syncops *so )
  {
  	so->s_flags |= PS_TASK_QUEUED;
  	so->s_inuse++;
  	ldap_pvt_thread_pool_submit2( &connection_pool,
  		syncprov_qtask, so, &so->s_pool_cookie );
  }
  
  /* Queue a persistent search response */
  static int
  syncprov_qresp( opcookie *opc, syncops *so, int mode )
  {
  	syncres *sr;
  	resinfo *ri;
  	int srsize;
  	struct berval csn = opc->sctxcsn;
  
  	sr = ch_malloc( sizeof( syncres ));
  	sr->s_next = NULL;
  	sr->s_mode = mode;
  	if ( !opc->ssres.s_info ) {
  
  		srsize = sizeof( resinfo );
  		if ( csn.bv_len )
  			srsize += csn.bv_len + 1;
  
  		if ( opc->se ) {
  			Attribute *a;
  			ri = ch_malloc( srsize );
  			ri->ri_dn = opc->se->e_name;
  			ri->ri_ndn = opc->se->e_nname;
  			a = attr_find( opc->se->e_attrs, slap_schema.si_ad_entryUUID );
  			if ( a )
  				ri->ri_uuid = a->a_nvals[0];
  			else
  				ri->ri_uuid.bv_len = 0;
  			if ( csn.bv_len ) {
  				ri->ri_csn.bv_val = (char *)(ri + 1);
  				ri->ri_csn.bv_len = csn.bv_len;
  				memcpy( ri->ri_csn.bv_val, csn.bv_val, csn.bv_len );
  				ri->ri_csn.bv_val[csn.bv_len] = '\0';
  			} else {
  				ri->ri_csn.bv_val = NULL;
  			}
  		} else {
  			srsize += opc->suuid.bv_len +
  				opc->sdn.bv_len + 1 + opc->sndn.bv_len + 1;
  			ri = ch_malloc( srsize );
  			ri->ri_dn.bv_val = (char *)(ri + 1);
  			ri->ri_dn.bv_len = opc->sdn.bv_len;
  			ri->ri_ndn.bv_val = lutil_strcopy( ri->ri_dn.bv_val,
  				opc->sdn.bv_val ) + 1;
  			ri->ri_ndn.bv_len = opc->sndn.bv_len;
  			ri->ri_uuid.bv_val = lutil_strcopy( ri->ri_ndn.bv_val,
  				opc->sndn.bv_val ) + 1;
  			ri->ri_uuid.bv_len = opc->suuid.bv_len;
  			AC_MEMCPY( ri->ri_uuid.bv_val, opc->suuid.bv_val, opc->suuid.bv_len );
  			if ( csn.bv_len ) {
  				ri->ri_csn.bv_val = ri->ri_uuid.bv_val + ri->ri_uuid.bv_len;
  				memcpy( ri->ri_csn.bv_val, csn.bv_val, csn.bv_len );
  				ri->ri_csn.bv_val[csn.bv_len] = '\0';
  			} else {
  				ri->ri_csn.bv_val = NULL;
  			}
  		}
  		ri->ri_list = &opc->ssres;
  		ri->ri_e = opc->se;
  		ri->ri_csn.bv_len = csn.bv_len;
  		ri->ri_isref = opc->sreference;
  		BER_BVZERO( &ri->ri_cookie );
  		ldap_pvt_thread_mutex_init( &ri->ri_mutex );
  		opc->se = NULL;
  		opc->ssres.s_info = ri;
  	}
  	ri = opc->ssres.s_info;
  	sr->s_info = ri;
  	ldap_pvt_thread_mutex_lock( &ri->ri_mutex );
  	sr->s_rilist = ri->ri_list;
  	ri->ri_list = sr;
  	if ( mode == LDAP_SYNC_NEW_COOKIE && BER_BVISNULL( &ri->ri_cookie )) {
  		syncprov_info_t	*si = opc->son->on_bi.bi_private;
  
  		slap_compose_sync_cookie( NULL, &ri->ri_cookie, si->si_ctxcsn,
  			so->s_rid, slap_serverID ? slap_serverID : -1, NULL );
  	}
  	Debug( LDAP_DEBUG_SYNC, "%s syncprov_qresp: "
  		"set up a new syncres mode=%d csn=%s\n",
  		so->s_op->o_log_prefix, mode, csn.bv_val ? csn.bv_val : "" );
  	ldap_pvt_thread_mutex_unlock( &ri->ri_mutex );
  
  	ldap_pvt_thread_mutex_lock( &so->s_mutex );
  	if ( !so->s_res ) {
  		so->s_res = sr;
  	} else {
  		so->s_restail->s_next = sr;
  	}
  	so->s_restail = sr;
  
  	/* If the base of the psearch was modified, check it next time round */
  	if ( so->s_flags & PS_WROTE_BASE ) {
  		so->s_flags ^= PS_WROTE_BASE;
  		so->s_flags |= PS_FIND_BASE;
  	}
  	if (( so->s_flags & (PS_IS_DETACHED|PS_TASK_QUEUED)) == PS_IS_DETACHED ) {
  		syncprov_qstart( so );
  	}
  	ldap_pvt_thread_mutex_unlock( &so->s_mutex );
  	return LDAP_SUCCESS;
  }
  
  static int
  syncprov_drop_psearch( syncops *so, int lock )
  {
  	if ( so->s_flags & PS_IS_DETACHED ) {
  		if ( lock )
  			ldap_pvt_thread_mutex_lock( &so->s_op->o_conn->c_mutex );
  		so->s_op->o_conn->c_n_ops_executing--;
  		so->s_op->o_conn->c_n_ops_completed++;
  		LDAP_STAILQ_REMOVE( &so->s_op->o_conn->c_ops, so->s_op, Operation,
  			o_next );
  		if ( lock )
  			ldap_pvt_thread_mutex_unlock( &so->s_op->o_conn->c_mutex );
  	}
  	return syncprov_free_syncop( so, FS_LOCK );
  }
  
  static int
  syncprov_ab_cleanup( Operation *op, SlapReply *rs )
  {
  	slap_callback *sc = op->o_callback;
  	op->o_callback = sc->sc_next;
  	syncprov_drop_psearch( sc->sc_private, 0 );
  	op->o_tmpfree( sc, op->o_tmpmemctx );
  	return 0;
  }
  
  static int
  syncprov_op_abandon( Operation *op, SlapReply *rs )
  {
  	slap_overinst		*on = (slap_overinst *)op->o_bd->bd_info;
  	syncprov_info_t		*si = on->on_bi.bi_private;
  	syncops *so, **sop;
  
  	ldap_pvt_thread_mutex_lock( &si->si_ops_mutex );
  	for ( sop=&si->si_ops; (so = *sop); sop = &(*sop)->s_next ) {
  		if ( so->s_op->o_connid == op->o_connid &&
  			so->s_op->o_msgid == op->orn_msgid ) {
  				so->s_op->o_abandon = 1;
  				*sop = so->s_next;
  				break;
  		}
  	}
  	ldap_pvt_thread_mutex_unlock( &si->si_ops_mutex );
  	if ( so ) {
  		/* Is this really a Cancel exop? */
  		if ( op->o_tag != LDAP_REQ_ABANDON ) {
  			so->s_op->o_cancel = SLAP_CANCEL_ACK;
  			rs->sr_err = LDAP_CANCELLED;
  			send_ldap_result( so->s_op, rs );
  			if ( so->s_flags & PS_IS_DETACHED ) {
  				slap_callback *cb;
  				cb = op->o_tmpcalloc( 1, sizeof(slap_callback), op->o_tmpmemctx );
  				cb->sc_cleanup = syncprov_ab_cleanup;
  				cb->sc_next = op->o_callback;
  				cb->sc_private = so;
  				op->o_callback = cb;
  				return SLAP_CB_CONTINUE;
  			}
  		}
  		syncprov_drop_psearch( so, 0 );
  	}
  	return SLAP_CB_CONTINUE;
  }
  
  /* Find which persistent searches are affected by this operation */
  static void
  syncprov_matchops( Operation *op, opcookie *opc, int saveit )
  {
  	slap_overinst *on = opc->son;
  	syncprov_info_t		*si = on->on_bi.bi_private;
  
  	fbase_cookie fc;
  	syncops **pss;
  	Entry *e = NULL;
  	Attribute *a;
  	int rc, gonext;
  	struct berval newdn;
  	int freefdn = 0;
  	BackendDB *b0 = op->o_bd, db;
  
  	fc.fdn = &op->o_req_ndn;
  	/* compute new DN */
  	if ( op->o_tag == LDAP_REQ_MODRDN && !saveit ) {
  		ber_dupbv_x( &newdn, &op->orr_nnewDN, op->o_tmpmemctx );
  		fc.fdn = &newdn;
  		freefdn = 1;
  	}
  	if ( !saveit && op->o_tag == LDAP_REQ_DELETE ) {
  		/* Delete succeeded, there is no entry */
  	} else if ( op->o_tag != LDAP_REQ_ADD ) {
  		if ( !SLAP_ISOVERLAY( op->o_bd )) {
  			db = *op->o_bd;
  			op->o_bd = &db;
  		}
  		rc = overlay_entry_get_ov( op, fc.fdn, NULL, NULL, 0, &e, on );
  		/* If we're sending responses now, make a copy and unlock the DB */
  		if ( e && !saveit ) {
  			if ( !opc->se )
  				opc->se = entry_dup( e );
  			overlay_entry_release_ov( op, e, 0, on );
  			e = opc->se;
  		}
  		if ( rc ) {
  			Debug( LDAP_DEBUG_SYNC, "%s syncprov_matchops: "
  				"%s check, error finding entry dn=%s in database\n",
  				op->o_log_prefix, saveit ? "initial" : "final", fc.fdn->bv_val );
  			op->o_bd = b0;
  			return;
  		}
  	} else {
  		e = op->ora_e;
  		if ( !saveit ) {
  			if ( !opc->se )
  				opc->se = entry_dup( e );
  			e = opc->se;
  		}
  	}
  
  	if ( saveit || op->o_tag == LDAP_REQ_ADD ) {
  		ber_dupbv_x( &opc->sdn, &e->e_name, op->o_tmpmemctx );
  		ber_dupbv_x( &opc->sndn, &e->e_nname, op->o_tmpmemctx );
  		opc->sreference = is_entry_referral( e );
  		a = attr_find( e->e_attrs, slap_schema.si_ad_entryUUID );
  		if ( a )
  			ber_dupbv_x( &opc->suuid, &a->a_nvals[0], op->o_tmpmemctx );
  		Debug( LDAP_DEBUG_SYNC, "%s syncprov_matchops: "
  			"%srecording uuid for dn=%s on opc=%p\n",
  			op->o_log_prefix, a ? "" : "not ", opc->sdn.bv_val, opc );
  	} else if ( op->o_tag == LDAP_REQ_MODRDN && !saveit ) {
  		op->o_tmpfree( opc->sndn.bv_val, op->o_tmpmemctx );
  		op->o_tmpfree( opc->sdn.bv_val, op->o_tmpmemctx );
  		ber_dupbv_x( &opc->sdn, &e->e_name, op->o_tmpmemctx );
  		ber_dupbv_x( &opc->sndn, &e->e_nname, op->o_tmpmemctx );
  	}
  
  	ldap_pvt_thread_mutex_lock( &si->si_ops_mutex );
  	for (pss = &si->si_ops; *pss; pss = gonext ? &(*pss)->s_next : pss)
  	{
  		Operation op2;
  		Opheader oh;
  		syncmatches *sm;
  		int found = 0;
  		syncops *snext, *ss = *pss;
  
  		gonext = 1;
  		if ( ss->s_op->o_abandon )
  			continue;
  
  		/* Don't send ops back to the originator */
  		if ( opc->osid > 0 && opc->osid == ss->s_sid ) {
  			Debug( LDAP_DEBUG_SYNC, "%s syncprov_matchops: "
  				"skipping original sid %03x\n",
  				ss->s_op->o_log_prefix, opc->osid );
  			continue;
  		}
  
  		/* Don't send ops back to the messenger */
  		if ( opc->rsid > 0 && opc->rsid == ss->s_sid ) {
  			Debug( LDAP_DEBUG_SYNC, "%s syncprov_matchops: "
  				"skipping relayed sid %03x\n",
  				ss->s_op->o_log_prefix, opc->rsid );
  			continue;
  		}
  
  		/* validate base */
  		fc.fss = ss;
  		fc.fbase = 0;
  		fc.fscope = 0;
  
  		/* If the base of the search is missing, signal a refresh */
  		rc = syncprov_findbase( op, &fc );
  		if ( rc != LDAP_SUCCESS ) {
  			SlapReply rs = {REP_RESULT};
  			send_ldap_error( ss->s_op, &rs, LDAP_SYNC_REFRESH_REQUIRED,
  				"search base has changed" );
  			snext = ss->s_next;
  			if ( syncprov_drop_psearch( ss, 1 ) )
  				*pss = snext;
  			gonext = 0;
  			continue;
  		}
  
  		/* If we're sending results now, look for this op in old matches */
  		if ( !saveit ) {
  			syncmatches *old;
  
  			/* Did we modify the search base? */
  			if ( dn_match( &op->o_req_ndn, &ss->s_base )) {
  				ldap_pvt_thread_mutex_lock( &ss->s_mutex );
  				ss->s_flags |= PS_WROTE_BASE;
  				ldap_pvt_thread_mutex_unlock( &ss->s_mutex );
  			}
  
  			for ( sm=opc->smatches, old=(syncmatches *)&opc->smatches; sm;
  				old=sm, sm=sm->sm_next ) {
  				if ( sm->sm_op == ss ) {
  					found = 1;
  					old->sm_next = sm->sm_next;
  					op->o_tmpfree( sm, op->o_tmpmemctx );
  					break;
  				}
  			}
  		}
  
  		rc = LDAP_COMPARE_FALSE;
  		if ( e && !is_entry_glue( e ) && fc.fscope ) {
  			ldap_pvt_thread_mutex_lock( &ss->s_mutex );
  			op2 = *ss->s_op;
  			oh = *op->o_hdr;
  			oh.oh_conn = ss->s_op->o_conn;
  			oh.oh_connid = ss->s_op->o_connid;
  			op2.o_bd = op->o_bd->bd_self;
  			op2.o_hdr = &oh;
  			op2.o_extra = op->o_extra;
  			op2.o_callback = NULL;
  			if (ss->s_flags & PS_FIX_FILTER) {
  				/* Skip the AND/GE clause that we stuck on in front. We
  				   would lose deletes/mods that happen during the refresh
  				   phase otherwise (ITS#6555) */
  				op2.ors_filter = ss->s_op->ors_filter->f_and->f_next;
  			}
  			rc = test_filter( &op2, e, op2.ors_filter );
  			ldap_pvt_thread_mutex_unlock( &ss->s_mutex );
  		}
  
  		Debug( LDAP_DEBUG_TRACE, "%s syncprov_matchops: "
  			"sid %03x fscope %d rc %d\n",
  			ss->s_op->o_log_prefix, ss->s_sid, fc.fscope, rc );
  
  		/* check if current o_req_dn is in scope and matches filter */
  		if ( fc.fscope && rc == LDAP_COMPARE_TRUE ) {
  			if ( saveit ) {
  				sm = op->o_tmpalloc( sizeof(syncmatches), op->o_tmpmemctx );
  				sm->sm_next = opc->smatches;
  				sm->sm_op = ss;
  				ldap_pvt_thread_mutex_lock( &ss->s_mutex );
  				++ss->s_inuse;
  				ldap_pvt_thread_mutex_unlock( &ss->s_mutex );
  				opc->smatches = sm;
  			} else {
  				/* if found send UPDATE else send ADD */
  				syncprov_qresp( opc, ss,
  					found ? LDAP_SYNC_MODIFY : LDAP_SYNC_ADD );
  			}
  		} else if ( !saveit && found ) {
  			/* send DELETE */
  			syncprov_qresp( opc, ss, LDAP_SYNC_DELETE );
  		} else if ( !saveit ) {
  			syncprov_qresp( opc, ss, LDAP_SYNC_NEW_COOKIE );
  		}
  		if ( !saveit && found ) {
  			/* Decrement s_inuse, was incremented when called
  			 * with saveit == TRUE
  			 */
  			snext = ss->s_next;
  			if ( syncprov_free_syncop( ss, FS_LOCK ) ) {
  				*pss = snext;
  				gonext = 0;
  			}
  		}
  	}
  	ldap_pvt_thread_mutex_unlock( &si->si_ops_mutex );
  
  	if ( op->o_tag != LDAP_REQ_ADD && e ) {
  		if ( !SLAP_ISOVERLAY( op->o_bd )) {
  			op->o_bd = &db;
  		}
  		if ( saveit )
  			overlay_entry_release_ov( op, e, 0, on );
  		op->o_bd = b0;
  	}
  	if ( !saveit ) {
  		if ( opc->ssres.s_info )
  			free_resinfo( &opc->ssres );
  		else if ( opc->se )
  			entry_free( opc->se );
  	}
  	if ( freefdn ) {
  		op->o_tmpfree( fc.fdn->bv_val, op->o_tmpmemctx );
  	}
  	op->o_bd = b0;
  }
  
  static int
  syncprov_op_cleanup( Operation *op, SlapReply *rs )
  {
  	slap_callback *cb = op->o_callback;
  	opcookie *opc = cb->sc_private;
  	slap_overinst *on = opc->son;
  	syncprov_info_t		*si = on->on_bi.bi_private;
  	syncmatches *sm, *snext;
  	modtarget *mt;
  
  	ldap_pvt_thread_mutex_lock( &si->si_ops_mutex );
  	if ( si->si_active )
  		si->si_active--;
  	ldap_pvt_thread_mutex_unlock( &si->si_ops_mutex );
  
  	for (sm = opc->smatches; sm; sm=snext) {
  		snext = sm->sm_next;
  		syncprov_free_syncop( sm->sm_op, FS_LOCK|FS_UNLINK );
  		op->o_tmpfree( sm, op->o_tmpmemctx );
  	}
  
  	/* Remove op from lock table */
  	mt = opc->smt;
  	if ( mt ) {
  		modinst *mi = (modinst *)(opc+1), **m2;
  		ldap_pvt_thread_mutex_lock( &mt->mt_mutex );
  		for (m2 = &mt->mt_mods; ; m2 = &(*m2)->mi_next) {
  			if ( *m2 == mi ) {
  				*m2 = mi->mi_next;
  				if ( mt->mt_tail == mi )
  					mt->mt_tail = ( m2 == &mt->mt_mods ) ? NULL : (modinst *)m2;
  				break;
  			}
  		}
  		/* If there are more, promote the next one */
  		if ( mt->mt_mods ) {
  			ldap_pvt_thread_mutex_unlock( &mt->mt_mutex );
  		} else {
  			ldap_pvt_thread_mutex_unlock( &mt->mt_mutex );
  			ldap_pvt_thread_mutex_lock( &si->si_mods_mutex );
  			ldap_avl_delete( &si->si_mods, mt, sp_avl_cmp );
  			ldap_pvt_thread_mutex_unlock( &si->si_mods_mutex );
  			ldap_pvt_thread_mutex_destroy( &mt->mt_mutex );
  			ch_free( mt->mt_dn.bv_val );
  			ch_free( mt );
  		}
  	}
  	if ( !BER_BVISNULL( &opc->suuid ))
  		op->o_tmpfree( opc->suuid.bv_val, op->o_tmpmemctx );
  	if ( !BER_BVISNULL( &opc->sndn ))
  		op->o_tmpfree( opc->sndn.bv_val, op->o_tmpmemctx );
  	if ( !BER_BVISNULL( &opc->sdn ))
  		op->o_tmpfree( opc->sdn.bv_val, op->o_tmpmemctx );
  	op->o_callback = cb->sc_next;
  
  	if ( opc->ssres.s_info ) {
  		free_resinfo( &opc->ssres );
  	}
  	op->o_tmpfree(cb, op->o_tmpmemctx);
  
  	return 0;
  }
  
  static void
  syncprov_checkpoint( Operation *op, slap_overinst *on )
  {
  	syncprov_info_t *si = (syncprov_info_t *)on->on_bi.bi_private;
  	Modifications mod;
  	Operation opm;
  	SlapReply rsm = {REP_RESULT};
  	slap_callback cb = {0};
  	BackendDB be;
  	BackendInfo *bi;
  
  #ifdef CHECK_CSN
  	Syntax *syn = slap_schema.si_ad_contextCSN->ad_type->sat_syntax;
  
  	int i;
  	for ( i=0; i<si->si_numcsns; i++ ) {
  		assert( !syn->ssyn_validate( syn, si->si_ctxcsn+i ));
  	}
  #endif
  
  	Debug( LDAP_DEBUG_SYNC, "%s syncprov_checkpoint: running checkpoint\n",
  		op->o_log_prefix );
  
  	mod.sml_numvals = si->si_numcsns;
  	mod.sml_values = si->si_ctxcsn;
  	mod.sml_nvalues = NULL;
  	mod.sml_desc = slap_schema.si_ad_contextCSN;
  	mod.sml_op = LDAP_MOD_REPLACE;
  	mod.sml_flags = SLAP_MOD_INTERNAL;
  	mod.sml_next = NULL;
  
  	cb.sc_response = slap_null_cb;
  	opm = *op;
  	opm.o_tag = LDAP_REQ_MODIFY;
  	opm.o_callback = &cb;
  	opm.orm_modlist = &mod;
  	opm.orm_no_opattrs = 1;
  	if ( SLAP_GLUE_SUBORDINATE( op->o_bd )) {
  		be = *on->on_info->oi_origdb;
  		opm.o_bd = &be;
  	}
  	opm.o_req_dn = si->si_contextdn;
  	opm.o_req_ndn = si->si_contextdn;
  	bi = opm.o_bd->bd_info;
  	opm.o_bd->bd_info = on->on_info->oi_orig;
  	opm.o_managedsait = SLAP_CONTROL_NONCRITICAL;
  	opm.o_no_schema_check = 1;
  	opm.o_dont_replicate = 1;
  	opm.o_opid = -1;
  	opm.o_bd->be_modify( &opm, &rsm );
  
  	if ( rsm.sr_err == LDAP_NO_SUCH_OBJECT &&
  		SLAP_SYNC_SUBENTRY( opm.o_bd )) {
  		const char	*text;
  		char txtbuf[SLAP_TEXT_BUFLEN];
  		size_t textlen = sizeof txtbuf;
  		Entry *e = slap_create_context_csn_entry( opm.o_bd, NULL );
  		rs_reinit( &rsm, REP_RESULT );
  		slap_mods2entry( &mod, &e, 0, 1, &text, txtbuf, textlen);
  		opm.ora_e = e;
  		opm.o_bd->be_add( &opm, &rsm );
  		if ( e == opm.ora_e )
  			be_entry_release_w( &opm, opm.ora_e );
  	}
  	opm.o_bd->bd_info = bi;
  
  	if ( mod.sml_next != NULL ) {
  		slap_mods_free( mod.sml_next, 1 );
  	}
  #ifdef CHECK_CSN
  	for ( i=0; i<si->si_numcsns; i++ ) {
  		assert( !syn->ssyn_validate( syn, si->si_ctxcsn+i ));
  	}
  #endif
  }
  
  static void
  syncprov_add_slog( Operation *op )
  {
  	opcookie *opc = op->o_callback->sc_private;
  	slap_overinst *on = opc->son;
  	syncprov_info_t		*si = on->on_bi.bi_private;
  	sessionlog *sl;
  	slog_entry *se;
  	char uuidstr[40];
  	int rc;
  
  	sl = si->si_logs;
  	{
  		if ( BER_BVISEMPTY( &op->o_csn ) ) {
  			/* During the syncrepl refresh phase we can receive operations
  			 * without a csn.  We cannot reliably determine the consumers
  			 * state with respect to such operations, so we ignore them and
  			 * wipe out anything in the log if we see them.
  			 */
  			ldap_pvt_thread_rdwr_wlock( &sl->sl_mutex );
  			/* can only do this if no one else is reading the log at the moment */
  			if ( !sl->sl_playing ) {
  				ldap_tavl_free( sl->sl_entries, (AVL_FREE)ch_free );
  				sl->sl_num = 0;
  				sl->sl_entries = NULL;
  			}
  			ldap_pvt_thread_rdwr_wunlock( &sl->sl_mutex );
  			return;
  		}
  
  		/* Allocate a record. UUIDs are not NUL-terminated. */
  		se = ch_malloc( sizeof( slog_entry ) + opc->suuid.bv_len +
  			op->o_csn.bv_len + 1 );
  		se->se_tag = op->o_tag;
  
  		se->se_uuid.bv_val = (char *)(&se[1]);
  		AC_MEMCPY( se->se_uuid.bv_val, opc->suuid.bv_val, opc->suuid.bv_len );
  		se->se_uuid.bv_len = opc->suuid.bv_len;
  
  		se->se_csn.bv_val = se->se_uuid.bv_val + opc->suuid.bv_len;
  		AC_MEMCPY( se->se_csn.bv_val, op->o_csn.bv_val, op->o_csn.bv_len );
  		se->se_csn.bv_val[op->o_csn.bv_len] = '\0';
  		se->se_csn.bv_len = op->o_csn.bv_len;
  		se->se_sid = slap_parse_csn_sid( &se->se_csn );
  
  		ldap_pvt_thread_rdwr_wlock( &sl->sl_mutex );
  		if ( LogTest( LDAP_DEBUG_SYNC ) ) {
  			uuidstr[0] = 0;
  			if ( !BER_BVISEMPTY( &opc->suuid ) ) {
  				lutil_uuidstr_from_normalized( opc->suuid.bv_val, opc->suuid.bv_len,
  					uuidstr, 40 );
  			}
  			Debug( LDAP_DEBUG_SYNC, "%s syncprov_add_slog: "
  				"adding csn=%s to sessionlog, uuid=%s\n",
  				op->o_log_prefix, se->se_csn.bv_val, uuidstr );
  		}
  		if ( !sl->sl_entries ) {
  			if ( !sl->sl_mincsn ) {
  				sl->sl_numcsns = 1;
  				sl->sl_mincsn = ch_malloc( 2*sizeof( struct berval ));
  				sl->sl_sids = ch_malloc( sizeof( int ));
  				sl->sl_sids[0] = se->se_sid;
  				ber_dupbv( sl->sl_mincsn, &se->se_csn );
  				BER_BVZERO( &sl->sl_mincsn[1] );
  			}
  		}
  		rc = ldap_tavl_insert( &sl->sl_entries, se, syncprov_sessionlog_cmp, ldap_avl_dup_error );
  		if ( rc ) {
  			Debug( LDAP_DEBUG_SYNC, "%s syncprov_add_slog: "
  				"duplicate sessionlog entry ignored: csn=%s, uuid=%s\n",
  				op->o_log_prefix, se->se_csn.bv_val, uuidstr );
  			ch_free( se );
  			goto leave;
  		}
  		sl->sl_num++;
  		if ( !sl->sl_playing && sl->sl_num > sl->sl_size ) {
  			TAvlnode *edge = ldap_tavl_end( sl->sl_entries, TAVL_DIR_LEFT );
  			while ( sl->sl_num > sl->sl_size ) {
  				int i;
  				TAvlnode *next = ldap_tavl_next( edge, TAVL_DIR_RIGHT );
  				se = edge->avl_data;
  				Debug( LDAP_DEBUG_SYNC, "%s syncprov_add_slog: "
  					"expiring csn=%s from sessionlog (sessionlog size=%d)\n",
  					op->o_log_prefix, se->se_csn.bv_val, sl->sl_num );
  				for ( i=0; i<sl->sl_numcsns; i++ )
  					if ( sl->sl_sids[i] >= se->se_sid )
  						break;
  				if  ( i == sl->sl_numcsns || sl->sl_sids[i] != se->se_sid ) {
  					Debug( LDAP_DEBUG_SYNC, "%s syncprov_add_slog: "
  						"adding csn=%s to mincsn\n",
  						op->o_log_prefix, se->se_csn.bv_val );
  					slap_insert_csn_sids( (struct sync_cookie *)sl,
  						i, se->se_sid, &se->se_csn );
  				} else {
  					Debug( LDAP_DEBUG_SYNC, "%s syncprov_add_slog: "
  						"updating mincsn for sid=%d csn=%s to %s\n",
  						op->o_log_prefix, se->se_sid, sl->sl_mincsn[i].bv_val, se->se_csn.bv_val );
  					ber_bvreplace( &sl->sl_mincsn[i], &se->se_csn );
  				}
  				ldap_tavl_delete( &sl->sl_entries, se, syncprov_sessionlog_cmp );
  				ch_free( se );
  				edge = next;
  				sl->sl_num--;
  			}
  		}
  leave:
  		ldap_pvt_thread_rdwr_wunlock( &sl->sl_mutex );
  	}
  }
  
  /* Just set a flag if we found the matching entry */
  static int
  playlog_cb( Operation *op, SlapReply *rs )
  {
  	if ( rs->sr_type == REP_SEARCH ) {
  		op->o_callback->sc_private = (void *)1;
  	}
  	return rs->sr_err;
  }
  
  /*
   * Check whether the last nmods UUIDs in the uuids list exist in the database
   * and (still) match the op filter, zero out the bv_len of any that still exist
   * and return the number of UUIDs we have confirmed are gone now.
   */
  static int
  check_uuidlist_presence(
  		Operation *op,
  		struct berval *uuids,
  		int len,
  		int nmods )
  {
  	slap_overinst *on = (slap_overinst *)op->o_bd->bd_info;
  	Operation fop = *op;
  	SlapReply frs = { REP_RESULT };
  	Filter mf, af;
  	AttributeAssertion eq = ATTRIBUTEASSERTION_INIT;
  	slap_callback cb = {0};
  	int i, mods = nmods;
  
  	fop.o_sync_mode = 0;
  	fop.o_callback = &cb;
  	fop.ors_limit = NULL;
  	fop.ors_tlimit = SLAP_NO_LIMIT;
  	fop.ors_attrs = slap_anlist_all_attributes;
  	fop.ors_attrsonly = 0;
  	fop.o_managedsait = SLAP_CONTROL_CRITICAL;
  	fop.o_dont_replicate = 1;
  
  	af.f_choice = LDAP_FILTER_AND;
  	af.f_next = NULL;
  	af.f_and = &mf;
  	mf.f_choice = LDAP_FILTER_EQUALITY;
  	mf.f_ava = &eq;
  	mf.f_av_desc = slap_schema.si_ad_entryUUID;
  	mf.f_next = fop.ors_filter;
  
  	fop.ors_filter = &af;
  
  	cb.sc_response = playlog_cb;
  
  	fop.o_bd->bd_info = (BackendInfo *)on->on_info;
  	for ( i=0; i<nmods; i++ ) {
  		mf.f_av_value = uuids[ len - 1 - i ];
  		cb.sc_private = NULL;
  		fop.ors_slimit = 1;
  
  		if ( BER_BVISEMPTY( &mf.f_av_value ) ) {
  			mods--;
  			continue;
  		}
  
  		rs_reinit( &frs, REP_RESULT );
  		fop.o_bd->be_search( &fop, &frs );
  		if ( cb.sc_private ) {
  			uuids[ len - 1 - i ].bv_len = 0;
  			mods--;
  		}
  	}
  	fop.o_bd->bd_info = (BackendInfo *)on;
  
  	return mods;
  }
  
  /*
   * On each entry we get from the DB:
   * - if it's an ADD, skip
   * - check we've not handled it yet, skip if we have
   * - check if it's a DELETE or missing from the DB now
   *   - send a new syncinfo entry
   * - remember we've handled it already
   *
   * If we exhaust the list, clear it, forgetting entries we've handled so far.
   */
  static int
  syncprov_accesslog_uuid_cb( Operation *op, SlapReply *rs )
  {
  	slap_callback *sc = op->o_callback;
  	syncprov_accesslog_deletes *uuid_progress = sc->sc_private;
  	Attribute *a, *attrs;
  	sync_control *srs = uuid_progress->srs;
  	struct berval *bv, csn[2] = {}, uuid[2] = {},
  				  add = BER_BVC("add"),
  				  delete = BER_BVC("delete"),
  				  modrdn = BER_BVC("modrdn");
  	int cmp, sid, i, is_delete = 0, rc;
  
  	if ( rs->sr_type != REP_SEARCH ) {
  		return rs->sr_err;
  	}
  	attrs = rs->sr_entry->e_attrs;
  
  	a = attr_find( attrs, ad_reqType );
  	if ( !a || a->a_numvals == 0 ) {
  		rs->sr_err = LDAP_CONSTRAINT_VIOLATION;
  		return rs->sr_err;
  	}
  
  	if ( bvmatch( &a->a_nvals[0], &add ) ) {
  		return rs->sr_err;
  	}
  
  	if ( bvmatch( &a->a_nvals[0], &delete ) ) {
  		is_delete = 1;
  	}
  
  	if ( bvmatch( &a->a_nvals[0], &modrdn ) ) {
  		a = attr_find( attrs, ad_reqDN );
  		if ( !a || a->a_numvals == 0 ) {
  			rs->sr_err = LDAP_CONSTRAINT_VIOLATION;
  			return rs->sr_err;
  		}
  
  		/* Was it present in the first place? If not, skip: */
  		if ( !dnIsSuffix( &a->a_nvals[0], &uuid_progress->op->o_req_ndn ) ) {
  			return rs->sr_err;
  		}
  
  		a = attr_find( attrs, ad_reqNewDN );
  		if ( !a || a->a_numvals == 0 ) {
  			rs->sr_err = LDAP_CONSTRAINT_VIOLATION;
  			return rs->sr_err;
  		}
  
  		/* Has it gone away? */
  		if ( !dnIsSuffix( &a->a_nvals[0], &uuid_progress->op->o_req_ndn ) ) {
  			is_delete = 1;
  		}
  	}
  
  	/*
  	 * Only pick entries that are both:
  	 */
  	a = attr_find( attrs, slap_schema.si_ad_entryCSN );
  	if ( !a || a->a_numvals == 0 ) {
  		rs->sr_err = LDAP_CONSTRAINT_VIOLATION;
  		return rs->sr_err;
  	}
  	csn[0] = a->a_nvals[0];
  
  	sid = slap_parse_csn_sid( &csn[0] );
  
  	/*
  	 * newer than cookieCSN (srs->sr_state.ctxcsn)
  	 */
  	cmp = 1;
  	for ( i=0; i<srs->sr_state.numcsns; i++ ) {
  		if ( sid == srs->sr_state.sids[i] ) {
  			cmp = ber_bvcmp( &csn[0], &srs->sr_state.ctxcsn[i] );
  			break;
  		}
  	}
  	if ( cmp <= 0 ) {
  		Debug( LDAP_DEBUG_SYNC, "%s syncprov_accesslog_uuid_cb: "
  				"cmp %d, csn %s too old\n",
  				op->o_log_prefix, cmp, csn[0].bv_val );
  		return rs->sr_err;
  	}
  
  	/*
  	 * not newer than snapshot ctxcsn (uuid_progress->ctxcsn)
  	 */
  	cmp = 0;
  	for ( i=0; i<uuid_progress->numcsns; i++ ) {
  		if ( sid == uuid_progress->sids[i] ) {
  			cmp = ber_bvcmp( &csn[0], &uuid_progress->ctxcsn[i] );
  			break;
  		}
  	}
  	if ( cmp > 0 ) {
  		Debug( LDAP_DEBUG_SYNC, "%s syncprov_accesslog_uuid_cb: "
  				"cmp %d, csn %s too new\n",
  				op->o_log_prefix, cmp, csn[0].bv_val );
  		return rs->sr_err;
  	}
  
  	a = attr_find( attrs, ad_reqEntryUUID );
  	if ( !a || a->a_numvals == 0 ) {
  		rs->sr_err = LDAP_CONSTRAINT_VIOLATION;
  		return rs->sr_err;
  	}
  	uuid[0] = a->a_nvals[0];
  
  	bv = ldap_avl_find( uuid_progress->uuids, uuid, sp_uuid_cmp );
  	if ( bv ) {
  		/* Already checked or sent, no change */
  		Debug( LDAP_DEBUG_SYNC, "%s syncprov_accesslog_uuid_cb: "
  				"uuid %s already checked\n",
  				op->o_log_prefix, a->a_vals[0].bv_val );
  		return rs->sr_err;
  	}
  
  	if ( !is_delete ) {
  		is_delete = check_uuidlist_presence( uuid_progress->op, uuid, 1, 1 );
  	}
  	Debug( LDAP_DEBUG_SYNC, "%s syncprov_accesslog_uuid_cb: "
  			"uuid %s is %s present\n",
  			op->o_log_prefix, a->a_vals[0].bv_val,
  			is_delete ? "no longer" : "still" );
  
  	i = uuid_progress->ndel++;
  
  	bv = &uuid_progress->uuid_list[i];
  	bv->bv_val = &uuid_progress->uuid_buf[i*UUID_LEN];
  	bv->bv_len = a->a_nvals[0].bv_len;
  	AC_MEMCPY( bv->bv_val, a->a_nvals[0].bv_val, a->a_nvals[0].bv_len );
  
  	rc = ldap_avl_insert( &uuid_progress->uuids, bv, sp_uuid_cmp, ldap_avl_dup_error );
  	assert( rc == LDAP_SUCCESS );
  
  	if ( is_delete ) {
  		struct berval cookie;
  
  		slap_compose_sync_cookie( op, &cookie, srs->sr_state.ctxcsn,
  				srs->sr_state.rid, slap_serverID ? slap_serverID : -1, csn );
  		syncprov_sendinfo( uuid_progress->op, uuid_progress->rs,
  				LDAP_TAG_SYNC_ID_SET, &cookie, 0, uuid, 1 );
  		op->o_tmpfree( cookie.bv_val, op->o_tmpmemctx );
  	}
  
  	if ( uuid_progress->ndel >= uuid_progress->list_len ) {
  		int ndel;
  
  		assert( uuid_progress->ndel == uuid_progress->list_len );
  		ndel = ldap_avl_free( uuid_progress->uuids, NULL );
  		assert( ndel == uuid_progress->ndel );
  		uuid_progress->uuids = NULL;
  		uuid_progress->ndel = 0;
  	}
  
  	return rs->sr_err;
  }
  
  static int
  syncprov_play_sessionlog( Operation *op, SlapReply *rs, sync_control *srs,
  		BerVarray ctxcsn, int numcsns, int *sids,
  		struct berval *mincsn, int minsid )
  {
  	slap_overinst		*on = (slap_overinst *)op->o_bd->bd_info;
  	syncprov_info_t *si = (syncprov_info_t *)on->on_bi.bi_private;
  	sessionlog *sl = si->si_logs;
  	int i, j, ndel, num, nmods, mmods, do_play = 0, rc = -1;
  	BerVarray uuids, csns;
  	struct berval uuid[2] = {}, csn[2] = {};
  	slog_entry *se;
  	TAvlnode *entry;
  	char cbuf[LDAP_PVT_CSNSTR_BUFSIZE];
  	struct berval delcsn[2];
  
  	ldap_pvt_thread_rdwr_wlock( &sl->sl_mutex );
  	/* Are there any log entries, and is the consumer state
  	 * present in the session log?
  	 */
  	if ( !sl->sl_num ) {
  		ldap_pvt_thread_rdwr_wunlock( &sl->sl_mutex );
  		return rc;
  	}
  	assert( sl->sl_num > 0 );
  
  	for ( i=0; i<sl->sl_numcsns; i++ ) {
  		/* SID not present == new enough */
  		if ( minsid < sl->sl_sids[i] ) {
  			do_play = 1;
  			break;
  		}
  		/* SID present */
  		if ( minsid == sl->sl_sids[i] ) {
  			/* new enough? */
  			if ( ber_bvcmp( mincsn, &sl->sl_mincsn[i] ) >= 0 )
  				do_play = 1;
  			break;
  		}
  	}
  	/* SID not present == new enough */
  	if ( i == sl->sl_numcsns )
  		do_play = 1;
  
  	if ( !do_play ) {
  		ldap_pvt_thread_rdwr_wunlock( &sl->sl_mutex );
  		return rc;
  	}
  
  	num = sl->sl_num;
  	i = 0;
  	nmods = 0;
  	sl->sl_playing++;
  	ldap_pvt_thread_rdwr_wunlock( &sl->sl_mutex );
  
  	uuids = op->o_tmpalloc( (num) * sizeof( struct berval ) +
  			num * UUID_LEN, op->o_tmpmemctx );
  	uuids[0].bv_val = (char *)(uuids + num);
  	csns = op->o_tmpalloc( (num) * sizeof( struct berval ) +
  			num * LDAP_PVT_CSNSTR_BUFSIZE, op->o_tmpmemctx );
  	csns[0].bv_val = (char *)(csns + num);
  
  	ldap_pvt_thread_rdwr_rlock( &sl->sl_mutex );
  	/* Make a copy of the relevant UUIDs. Put the Deletes up front
  	 * and everything else at the end. Do this first so we can
  	 * let the write side manage the sessionlog again.
  	 */
  	assert( sl->sl_entries );
  
  	/* Find first relevant log entry. If greater than mincsn, backtrack one entry */
  	{
  		slog_entry te = {0};
  		te.se_csn = *mincsn;
  		entry = ldap_tavl_find3( sl->sl_entries, &te, syncprov_sessionlog_cmp, &ndel );
  	}
  	if ( ndel > 0 && entry )
  		entry = ldap_tavl_next( entry, TAVL_DIR_LEFT );
  	/* if none, just start at beginning */
  	if ( !entry )
  		entry = ldap_tavl_end( sl->sl_entries, TAVL_DIR_LEFT );
  
  	do {
  		char uuidstr[40] = {};
  		slog_entry *se = entry->avl_data;
  		int k;
  
  		/* Make sure writes can still make progress */
  		ldap_pvt_thread_rdwr_runlock( &sl->sl_mutex );
  		ndel = 1;
  		for ( k=0; k<srs->sr_state.numcsns; k++ ) {
  			if ( se->se_sid == srs->sr_state.sids[k] ) {
  				ndel = ber_bvcmp( &se->se_csn, &srs->sr_state.ctxcsn[k] );
  				break;
  			}
  		}
  		if ( ndel <= 0 ) {
  			ldap_pvt_thread_rdwr_rlock( &sl->sl_mutex );
  			continue;
  		}
  		ndel = 0;
  		for ( k=0; k<numcsns; k++ ) {
  			if ( se->se_sid == sids[k] ) {
  				ndel = ber_bvcmp( &se->se_csn, &ctxcsn[k] );
  				break;
  			}
  		}
  		if ( ndel > 0 ) {
  			Debug( LDAP_DEBUG_SYNC, "%s syncprov_play_sessionlog: "
  				"cmp %d, csn %s too new, we're finished\n",
  				op->o_log_prefix, ndel, se->se_csn.bv_val );
  			ldap_pvt_thread_rdwr_rlock( &sl->sl_mutex );
  			break;
  		}
  		if ( se->se_tag == LDAP_REQ_DELETE ) {
  			j = i;
  			i++;
  		} else {
  			if ( se->se_tag == LDAP_REQ_ADD ) {
  				ldap_pvt_thread_rdwr_rlock( &sl->sl_mutex );
  				continue;
  			}
  			nmods++;
  			j = num - nmods;
  		}
  		uuids[j].bv_val = uuids[0].bv_val + (j * UUID_LEN);
  		AC_MEMCPY(uuids[j].bv_val, se->se_uuid.bv_val, UUID_LEN);
  		uuids[j].bv_len = UUID_LEN;
  
  		csns[j].bv_val = csns[0].bv_val + (j * LDAP_PVT_CSNSTR_BUFSIZE);
  		AC_MEMCPY(csns[j].bv_val, se->se_csn.bv_val, se->se_csn.bv_len);
  		csns[j].bv_len = se->se_csn.bv_len;
  		/* We're printing it */
  		csns[j].bv_val[csns[j].bv_len] = '\0';
  
  		if ( LogTest( LDAP_DEBUG_SYNC ) ) {
  			lutil_uuidstr_from_normalized( uuids[j].bv_val, uuids[j].bv_len,
  					uuidstr, 40 );
  			Debug( LDAP_DEBUG_SYNC, "%s syncprov_play_sessionlog: "
  				"picking a %s entry uuid=%s cookie=%s\n",
  				op->o_log_prefix, se->se_tag == LDAP_REQ_DELETE ? "deleted" : "modified",
  				uuidstr, csns[j].bv_val );
  		}
  		ldap_pvt_thread_rdwr_rlock( &sl->sl_mutex );
  	} while ( (entry = ldap_tavl_next( entry, TAVL_DIR_RIGHT )) != NULL );
  	ldap_pvt_thread_rdwr_runlock( &sl->sl_mutex );
  	ldap_pvt_thread_rdwr_wlock( &sl->sl_mutex );
  	sl->sl_playing--;
  	ldap_pvt_thread_rdwr_wunlock( &sl->sl_mutex );
  
  	ndel = i;
  
  	/* Zero out unused slots */
  	for ( i=ndel; i < num - nmods; i++ )
  		uuids[i].bv_len = 0;
  
  	/* Mods must be validated to see if they belong in this delete set.
  	 */
  
  	mmods = nmods;
  	/* Strip any duplicates */
  	for ( i=0; i<nmods; i++ ) {
  		for ( j=0; j<ndel; j++ ) {
  			if ( bvmatch( &uuids[j], &uuids[num - 1 - i] )) {
  				uuids[num - 1 - i].bv_len = 0;
  				mmods --;
  				break;
  			}
  		}
  		if ( uuids[num - 1 - i].bv_len == 0 ) continue;
  		for ( j=0; j<i; j++ ) {
  			if ( bvmatch( &uuids[num - 1 - j], &uuids[num - 1 - i] )) {
  				uuids[num - 1 - i].bv_len = 0;
  				mmods --;
  				break;
  			}
  		}
  	}
  
  	/* Check mods now */
  	if ( mmods ) {
  		check_uuidlist_presence( op, uuids, num, nmods );
  	}
  
  	/* ITS#8768 Send entries sorted by CSN order */
  	i = j = 0;
  	while ( i < ndel || j < nmods ) {
  		struct berval cookie;
  		int index;
  
  		/* Skip over duplicate mods */
  		if ( j < nmods && BER_BVISEMPTY( &uuids[ num - 1 - j ] ) ) {
  			j++;
  			continue;
  		}
  		index = num - 1 - j;
  
  		if ( i >= ndel ) {
  			j++;
  		} else if ( j >= nmods ) {
  			index = i++;
  		/* Take the oldest by CSN order */
  		} else if ( ber_bvcmp( &csns[index], &csns[i] ) < 0 ) {
  			j++;
  		} else {
  			index = i++;
  		}
  
  		uuid[0] = uuids[index];
  		csn[0] = csns[index];
  
  		slap_compose_sync_cookie( op, &cookie, srs->sr_state.ctxcsn,
  				srs->sr_state.rid, slap_serverID ? slap_serverID : -1, csn );
  		if ( LogTest( LDAP_DEBUG_SYNC ) ) {
  			char uuidstr[40];
  			lutil_uuidstr_from_normalized( uuid[0].bv_val, uuid[0].bv_len,
  					uuidstr, 40 );
  			Debug( LDAP_DEBUG_SYNC, "%s syncprov_play_sessionlog: "
  					"sending a new disappearing entry uuid=%s cookie=%s\n",
  					op->o_log_prefix, uuidstr, cookie.bv_val );
  		}
  
  		/* TODO: we might batch those that share the same CSN (think present
  		 * phase), but would have to limit how many we send out at once */
  		syncprov_sendinfo( op, rs, LDAP_TAG_SYNC_ID_SET, &cookie, 0, uuid, 1 );
  	}
  	op->o_tmpfree( uuids, op->o_tmpmemctx );
  	op->o_tmpfree( csns, op->o_tmpmemctx );
  
  	return LDAP_SUCCESS;
  }
  
  static int
  syncprov_play_accesslog( Operation *op, SlapReply *rs, sync_control *srs,
  		BerVarray ctxcsn, int numcsns, int *sids,
  		struct berval *mincsn, int minsid )
  {
  	slap_overinst *on = (slap_overinst *)op->o_bd->bd_info;
  	syncprov_info_t *si = on->on_bi.bi_private;
  	Operation fop;
  	SlapReply frs = { REP_RESULT };
  	slap_callback cb = {};
  	Filter *f;
  	syncprov_accesslog_deletes uuid_progress = {
  		.op = op,
  		.rs = rs,
  		.srs = srs,
  		.ctxcsn = ctxcsn,
  		.numcsns = numcsns,
  		.sids = sids,
  	};
  	struct berval oldestcsn = BER_BVNULL, newestcsn = BER_BVNULL,
  	basedn, filterpattern = BER_BVC(
  			"(&"
  				"(entryCSN>=%s)"
  				"(entryCSN<=%s)"
  				"(reqResult=0)"
  				"(|"
  					"(reqDN:dnSubtreeMatch:=%s)"
  					"(reqNewDN:dnSubtreeMatch:=%s)"
  				")"
  				"(|"
  					"(objectclass=auditWriteObject)"
  					"(objectclass=auditExtended)"
  			"))" );
  	BackendDB *db;
  	Entry *e;
  	Attribute *a;
  	int *minsids, i, j = 0, rc = -1;
  
  	assert( !BER_BVISNULL( &si->si_logbase ) );
  
  	db = select_backend( &si->si_logbase, 0 );
  	if ( !db ) {
  		Debug( LDAP_DEBUG_ANY, "%s syncprov_play_accesslog: "
  				"No database configured to hold accesslog dn=%s\n",
  				op->o_log_prefix, si->si_logbase.bv_val );
  		return LDAP_NO_SUCH_OBJECT;
  	}
  
  	fop = *op;
  	fop.o_sync_mode = 0;
  	fop.o_dont_replicate = 1;
  	fop.o_bd = db;
  	rc = be_entry_get_rw( &fop, &si->si_logbase, NULL, ad_minCSN, 0, &e );
  	if ( rc ) {
  		return rc;
  	}
  
  	a = attr_find( e->e_attrs, ad_minCSN );
  	if ( !a ) {
  		be_entry_release_rw( &fop, e, 0 );
  		return LDAP_NO_SUCH_ATTRIBUTE;
  	}
  
  	/*
  	 * If we got here:
  	 * - the consumer's cookie (srs->sr_state.ctxcsn) has the same sids in the
  	 *   same order as ctxcsn
  	 * - at least one of the cookie's csns is older than its ctxcsn counterpart
  	 *
  	 * Now prepare the filter, we want it to be the union of all the intervals
  	 * between the cookie and our contextCSN for each sid. Right now, we can't
  	 * specify them separately, so just pick the boundary CSNs of non-empty
  	 * intervals as a conservative overestimate.
  	 *
  	 * Also check accesslog can actually serve this query based on what's
  	 * stored in minCSN.
  	 */
  
  	assert( srs->sr_state.numcsns == numcsns );
  
  	minsids = slap_parse_csn_sids( a->a_nvals, a->a_numvals, op->o_tmpmemctx );
  	slap_sort_csn_sids( a->a_nvals, minsids, a->a_numvals, op->o_tmpmemctx );
  	for ( i=0, j=0; i < numcsns; i++ ) {
  		assert( srs->sr_state.sids[i] == sids[i] );
  		if ( ber_bvcmp( &srs->sr_state.ctxcsn[i], &ctxcsn[i] ) >= 0 ) {
  			/* Consumer is up to date for this sid */
  			continue;
  		}
  		for ( ; j < a->a_numvals && minsids[j] < sids[i]; j++ )
  			/* Find the right minCSN, if present */;
  		if ( j == a->a_numvals || minsids[j] != sids[i] ||
  				ber_bvcmp( &srs->sr_state.ctxcsn[i], &a->a_nvals[j] ) < 0 ) {
  			/* Consumer is missing changes for a sid and minCSN indicates we
  			 * can't replay all relevant history */
  			Debug( LDAP_DEBUG_SYNC, "%s syncprov_play_accesslog: "
  					"accesslog information inadequate for log replay on csn=%s\n",
  					op->o_log_prefix, srs->sr_state.ctxcsn[i].bv_val );
  			slap_sl_free( minsids, op->o_tmpmemctx );
  			be_entry_release_rw( &fop, e, 0 );
  			return 1;
  		}
  		if ( BER_BVISEMPTY( &oldestcsn ) ||
  				ber_bvcmp( &oldestcsn, &srs->sr_state.ctxcsn[i] ) > 0 ) {
  			oldestcsn = srs->sr_state.ctxcsn[i];
  		}
  		if ( BER_BVISEMPTY( &newestcsn ) ||
  				ber_bvcmp( &newestcsn, &ctxcsn[i] ) < 0 ) {
  			newestcsn = ctxcsn[i];
  		}
  	}
  	assert( !BER_BVISEMPTY( &oldestcsn ) && !BER_BVISEMPTY( &newestcsn ) &&
  			ber_bvcmp( &oldestcsn, &newestcsn ) < 0 );
  	slap_sl_free( minsids, op->o_tmpmemctx );
  
  	filter_escape_value_x( &op->o_req_ndn, &basedn, fop.o_tmpmemctx );
  	/* filter_escape_value_x sets output to BVNULL if input value is empty,
  	 * supply our own copy */
  	if ( BER_BVISEMPTY( &basedn ) ) {
  		basedn.bv_val = "";
  	}
  	fop.o_req_ndn = fop.o_req_dn = si->si_logbase;
  	fop.ors_filterstr.bv_val = fop.o_tmpalloc(
  			filterpattern.bv_len +
  			oldestcsn.bv_len + newestcsn.bv_len + 2 * basedn.bv_len,
  			fop.o_tmpmemctx );
  	fop.ors_filterstr.bv_len = sprintf( fop.ors_filterstr.bv_val,
  			filterpattern.bv_val,
  			oldestcsn.bv_val, newestcsn.bv_val, basedn.bv_val, basedn.bv_val );
  	Debug( LDAP_DEBUG_SYNC, "%s syncprov_play_accesslog: "
  			"prepared filter '%s', base='%s'\n",
  			op->o_log_prefix, fop.ors_filterstr.bv_val, si->si_logbase.bv_val );
  	f = str2filter_x( &fop, fop.ors_filterstr.bv_val );
  	assert( f != NULL );
  	fop.ors_filter = f;
  
  	if ( !BER_BVISEMPTY( &basedn ) ) {
  		fop.o_tmpfree( basedn.bv_val, fop.o_tmpmemctx );
  	}
  	be_entry_release_rw( &fop, e, 0 );
  
  	/*
  	 * Allocate memory for list_len uuids for use by the callback, populate
  	 * with entries that we have sent or checked still match the filter.
  	 * A disappearing entry gets its uuid sent as a delete.
  	 *
  	 * in the callback, we need:
  	 * - original op and rs so we can send the message
  	 * - sync_control
  	 * - the uuid buffer and list and their length
  	 * - number of uuids we already have in the list
  	 * - the lookup structure so we don't have to check/send a uuid twice
  	 *   (AVL?)
  	 */
  	uuid_progress.list_len = SLAP_SYNCUUID_SET_SIZE;
  	uuid_progress.uuid_list = fop.o_tmpalloc( (uuid_progress.list_len) * sizeof(struct berval), fop.o_tmpmemctx );
  	uuid_progress.uuid_buf = fop.o_tmpalloc( (uuid_progress.list_len) * UUID_LEN, fop.o_tmpmemctx );
  
  	cb.sc_private = &uuid_progress;
  	cb.sc_response = syncprov_accesslog_uuid_cb;
  
  	fop.o_callback = &cb;
  
  	rc = fop.o_bd->be_search( &fop, &frs );
  
  	ldap_avl_free( uuid_progress.uuids, NULL );
  	fop.o_tmpfree( uuid_progress.uuid_buf, fop.o_tmpmemctx );
  	fop.o_tmpfree( uuid_progress.uuid_list, fop.o_tmpmemctx );
  	fop.o_tmpfree( fop.ors_filterstr.bv_val, fop.o_tmpmemctx );
  	filter_free_x( &fop, f, 1 );
  
  	return rc;
  }
  
  static int
  syncprov_new_ctxcsn( opcookie *opc, syncprov_info_t *si, int csn_changed, int numvals, BerVarray vals )
  {
  	unsigned i;
  	int j, sid;
  
  	for ( i=0; i<numvals; i++ ) {
  		sid = slap_parse_csn_sid( &vals[i] );
  		for ( j=0; j<si->si_numcsns; j++ ) {
  			if ( sid < si->si_sids[j] )
  				break;
  			if ( sid == si->si_sids[j] ) {
  				if ( ber_bvcmp( &vals[i], &si->si_ctxcsn[j] ) > 0 ) {
  					ber_bvreplace( &si->si_ctxcsn[j], &vals[i] );
  					csn_changed = 1;
  				}
  				break;
  			}
  		}
  
  		if ( j == si->si_numcsns || sid != si->si_sids[j] ) {
  			slap_insert_csn_sids( (struct sync_cookie *)&si->si_ctxcsn,
  				j, sid, &vals[i] );
  			csn_changed = 1;
  		}
  	}
  	if ( csn_changed )
  		si->si_dirty = 0;
  	ldap_pvt_thread_rdwr_wunlock( &si->si_csn_rwlock );
  
  	if ( csn_changed ) {
  		syncops *ss;
  		ldap_pvt_thread_mutex_lock( &si->si_ops_mutex );
  		for ( ss = si->si_ops; ss; ss = ss->s_next ) {
  			if ( ss->s_op->o_abandon )
  				continue;
  			/* Send the updated csn to all syncrepl consumers,
  			 * including the server from which it originated.
  			 * The syncrepl consumer and syncprov provider on
  			 * the originating server may be configured to store
  			 * their csn values in different entries.
  			 */
  			syncprov_qresp( opc, ss, LDAP_SYNC_NEW_COOKIE );
  		}
  		ldap_pvt_thread_mutex_unlock( &si->si_ops_mutex );
  	}
  	return csn_changed;
  }
  
  static int
  syncprov_op_response( Operation *op, SlapReply *rs )
  {
  	opcookie *opc = op->o_callback->sc_private;
  	slap_overinst *on = opc->son;
  	syncprov_info_t		*si = on->on_bi.bi_private;
  	syncmatches *sm;
  
  	if ( rs->sr_err == LDAP_SUCCESS )
  	{
  		struct berval maxcsn;
  		char cbuf[LDAP_PVT_CSNSTR_BUFSIZE];
  		int do_check = 0, have_psearches, foundit, csn_changed = 0;
  
  		ldap_pvt_thread_mutex_lock( &si->si_resp_mutex );
  
  		/* Update our context CSN */
  		cbuf[0] = '\0';
  		maxcsn.bv_val = cbuf;
  		maxcsn.bv_len = sizeof(cbuf);
  		ldap_pvt_thread_rdwr_wlock( &si->si_csn_rwlock );
  
  		slap_get_commit_csn( op, &maxcsn, &foundit );
  		if ( BER_BVISEMPTY( &maxcsn ) && SLAP_GLUE_SUBORDINATE( op->o_bd )) {
  			/* syncrepl queues the CSN values in the db where
  			 * it is configured , not where the changes are made.
  			 * So look for a value in the glue db if we didn't
  			 * find any in this db.
  			 */
  			BackendDB *be = op->o_bd;
  			op->o_bd = select_backend( &be->be_nsuffix[0], 1);
  			maxcsn.bv_val = cbuf;
  			maxcsn.bv_len = sizeof(cbuf);
  			slap_get_commit_csn( op, &maxcsn, &foundit );
  			op->o_bd = be;
  		}
  		if ( !BER_BVISEMPTY( &maxcsn ) ) {
  			int i, sid;
  #ifdef CHECK_CSN
  			Syntax *syn = slap_schema.si_ad_contextCSN->ad_type->sat_syntax;
  			assert( !syn->ssyn_validate( syn, &maxcsn ));
  #endif
  			sid = slap_parse_csn_sid( &maxcsn );
  			for ( i=0; i<si->si_numcsns; i++ ) {
  				if ( sid < si->si_sids[i] )
  					break;
  				if ( sid == si->si_sids[i] ) {
  					if ( ber_bvcmp( &maxcsn, &si->si_ctxcsn[i] ) > 0 ) {
  						ber_bvreplace( &si->si_ctxcsn[i], &maxcsn );
  						csn_changed = 1;
  					}
  					break;
  				}
  			}
  			/* It's a new SID for us */
  			if ( i == si->si_numcsns || sid != si->si_sids[i] ) {
  				slap_insert_csn_sids((struct sync_cookie *)&(si->si_ctxcsn),
  					i, sid, &maxcsn );
  				csn_changed = 1;
  			}
  		}
  
  		/* Don't do any processing for consumer contextCSN updates */
  		if ( SLAPD_SYNC_IS_SYNCCONN( op->o_connid ) &&
  			op->o_tag == LDAP_REQ_MODIFY &&
  			op->orm_modlist &&
  			op->orm_modlist->sml_op == LDAP_MOD_REPLACE &&
  			op->orm_modlist->sml_desc == slap_schema.si_ad_contextCSN ) {
  			/* Catch contextCSN updates from syncrepl. We have to look at
  			 * all the attribute values, as there may be more than one csn
  			 * that changed, and only one can be passed in the csn queue.
  			 */
  			csn_changed = syncprov_new_ctxcsn( opc, si, csn_changed,
  				op->orm_modlist->sml_numvals, op->orm_modlist->sml_values );
  			if ( csn_changed )
  				si->si_numops++;
  			goto leave;
  		}
  		if ( op->o_dont_replicate ) {
  			if ( csn_changed )
  				si->si_numops++;
  			ldap_pvt_thread_rdwr_wunlock( &si->si_csn_rwlock );
  			goto leave;
  		}
  
  		/* If we're adding the context entry, parse all of its contextCSNs */
  		if ( op->o_tag == LDAP_REQ_ADD &&
  			dn_match( &op->o_req_ndn, &si->si_contextdn )) {
  			Attribute *a = attr_find( op->ora_e->e_attrs, slap_schema.si_ad_contextCSN );
  			if ( a ) {
  				csn_changed = syncprov_new_ctxcsn( opc, si, csn_changed, a->a_numvals, a->a_vals );
  				if ( csn_changed )
  					si->si_numops++;
  				goto added;
  			}
  		}
  
  		if ( csn_changed )
  			si->si_numops++;
  		if ( si->si_chkops || si->si_chktime ) {
  			/* Never checkpoint adding the context entry,
  			 * it will deadlock
  			 */
  			if ( op->o_tag != LDAP_REQ_ADD ||
  				!dn_match( &op->o_req_ndn, &si->si_contextdn )) {
  				if ( si->si_chkops && si->si_numops >= si->si_chkops ) {
  					do_check = 1;
  					si->si_numops = 0;
  				}
  				if ( si->si_chktime &&
  					(op->o_time - si->si_chklast >= si->si_chktime )) {
  					if ( si->si_chklast ) {
  						do_check = 1;
  						si->si_chklast = op->o_time;
  					} else {
  						si->si_chklast = 1;
  					}
  				}
  			}
  		}
  		si->si_dirty = !csn_changed;
  		ldap_pvt_thread_rdwr_wunlock( &si->si_csn_rwlock );
  
  added:
  		if ( do_check ) {
  			ldap_pvt_thread_rdwr_rlock( &si->si_csn_rwlock );
  			syncprov_checkpoint( op, on );
  			ldap_pvt_thread_rdwr_runlock( &si->si_csn_rwlock );
  		}
  
  		/* only update consumer ctx if this is a newer csn */
  		if ( csn_changed ) {
  			opc->sctxcsn = maxcsn;
  		}
  
  		/* Handle any persistent searches */
  		ldap_pvt_thread_mutex_lock( &si->si_ops_mutex );
  		have_psearches = ( si->si_ops != NULL );
  		ldap_pvt_thread_mutex_unlock( &si->si_ops_mutex );
  		if ( have_psearches ) {
  			syncprov_matchops( op, opc, 0 );
  		}
  
  		/* Add any log records */
  		if ( si->si_logs ) {
  			syncprov_add_slog( op );
  		}
  leave:		ldap_pvt_thread_mutex_unlock( &si->si_resp_mutex );
  	}
  	return SLAP_CB_CONTINUE;
  }
  
  /* We don't use a subentry to store the context CSN any more.
   * We expose the current context CSN as an operational attribute
   * of the suffix entry.
   */
  static int
  syncprov_op_compare( Operation *op, SlapReply *rs )
  {
  	slap_overinst		*on = (slap_overinst *)op->o_bd->bd_info;
  	syncprov_info_t		*si = on->on_bi.bi_private;
  	int rc = SLAP_CB_CONTINUE;
  
  	if ( dn_match( &op->o_req_ndn, &si->si_contextdn ) &&
  		op->oq_compare.rs_ava->aa_desc == slap_schema.si_ad_contextCSN )
  	{
  		Entry e = {0};
  		Attribute a = {0};
  
  		e.e_name = si->si_contextdn;
  		e.e_nname = si->si_contextdn;
  		e.e_attrs = &a;
  
  		a.a_desc = slap_schema.si_ad_contextCSN;
  
  		ldap_pvt_thread_rdwr_rlock( &si->si_csn_rwlock );
  
  		a.a_vals = si->si_ctxcsn;
  		a.a_nvals = a.a_vals;
  		a.a_numvals = si->si_numcsns;
  
  		rs->sr_err = access_allowed( op, &e, op->oq_compare.rs_ava->aa_desc,
  			&op->oq_compare.rs_ava->aa_value, ACL_COMPARE, NULL );
  		if ( ! rs->sr_err ) {
  			rs->sr_err = LDAP_INSUFFICIENT_ACCESS;
  			goto return_results;
  		}
  
  		if ( get_assert( op ) &&
  			( test_filter( op, &e, get_assertion( op ) ) != LDAP_COMPARE_TRUE ) )
  		{
  			rs->sr_err = LDAP_ASSERTION_FAILED;
  			goto return_results;
  		}
  
  
  		rs->sr_err = LDAP_COMPARE_FALSE;
  
  		if ( attr_valfind( &a,
  			SLAP_MR_ATTRIBUTE_VALUE_NORMALIZED_MATCH |
  				SLAP_MR_ASSERTED_VALUE_NORMALIZED_MATCH,
  				&op->oq_compare.rs_ava->aa_value, NULL, op->o_tmpmemctx ) == 0 )
  		{
  			rs->sr_err = LDAP_COMPARE_TRUE;
  		}
  
  return_results:;
  
  		ldap_pvt_thread_rdwr_runlock( &si->si_csn_rwlock );
  
  		send_ldap_result( op, rs );
  
  		if( rs->sr_err == LDAP_COMPARE_FALSE || rs->sr_err == LDAP_COMPARE_TRUE ) {
  			rs->sr_err = LDAP_SUCCESS;
  		}
  		rc = rs->sr_err;
  	}
  
  	return rc;
  }
  
  static int
  syncprov_op_mod( Operation *op, SlapReply *rs )
  {
  	slap_overinst		*on = (slap_overinst *)op->o_bd->bd_info;
  	syncprov_info_t		*si = on->on_bi.bi_private;
  	slap_callback *cb;
  	opcookie *opc;
  	int have_psearches, cbsize;
  
  	ldap_pvt_thread_mutex_lock( &si->si_ops_mutex );
  	have_psearches = ( si->si_ops != NULL );
  	si->si_active++;
  	ldap_pvt_thread_mutex_unlock( &si->si_ops_mutex );
  
  	cbsize = sizeof(slap_callback) + sizeof(opcookie) +
  		(have_psearches ? sizeof(modinst) : 0 );
  
  	cb = op->o_tmpcalloc(1, cbsize, op->o_tmpmemctx);
  	opc = (opcookie *)(cb+1);
  	opc->son = on;
  	cb->sc_response = syncprov_op_response;
  	cb->sc_cleanup = syncprov_op_cleanup;
  	cb->sc_private = opc;
  	cb->sc_next = op->o_callback;
  	op->o_callback = cb;
  
  	opc->osid = -1;
  	opc->rsid = -1;
  	if ( op->o_csn.bv_val ) {
  		opc->osid = slap_parse_csn_sid( &op->o_csn );
  	}
  	if ( op->o_controls ) {
  		struct sync_cookie *scook =
  		op->o_controls[slap_cids.sc_LDAPsync];
  		if ( scook )
  			opc->rsid = scook->sid;
  	}
  
  	if ( op->o_dont_replicate )
  		return SLAP_CB_CONTINUE;
  
  	/* If there are active persistent searches, lock this operation.
  	 * See seqmod.c for the locking logic on its own.
  	 */
  	if ( have_psearches ) {
  		modtarget *mt, mtdummy;
  		modinst *mi;
  
  		mi = (modinst *)(opc+1);
  		mi->mi_op = op;
  
  		/* See if we're already modifying this entry... */
  		mtdummy.mt_dn = op->o_req_ndn;
  retry:
  		ldap_pvt_thread_mutex_lock( &si->si_mods_mutex );
  		mt = ldap_avl_find( si->si_mods, &mtdummy, sp_avl_cmp );
  		if ( mt ) {
  			ldap_pvt_thread_mutex_lock( &mt->mt_mutex );
  			if ( mt->mt_mods == NULL ) {
  				/* Cannot reuse this mt, as another thread is about
  				 * to release it in syncprov_op_cleanup. Wait for them
  				 * to finish; our own insert is required to succeed.
  				 */
  				ldap_pvt_thread_mutex_unlock( &mt->mt_mutex );
  				ldap_pvt_thread_mutex_unlock( &si->si_mods_mutex );
  				ldap_pvt_thread_yield();
  				goto retry;
  			}
  		}
  		if ( mt ) {
  			mt->mt_tail->mi_next = mi;
  			mt->mt_tail = mi;
  			ldap_pvt_thread_mutex_unlock( &si->si_mods_mutex );
  			/* wait for this op to get to head of list */
  			while ( mt->mt_mods != mi ) {
  				modinst *m2;
  				/* don't wait on other mods from the same thread */
  				for ( m2 = mt->mt_mods; m2; m2 = m2->mi_next ) {
  					if ( m2->mi_op->o_threadctx == op->o_threadctx ) {
  						break;
  					}
  				}
  				if ( m2 )
  					break;
  
  				ldap_pvt_thread_mutex_unlock( &mt->mt_mutex );
  				/* FIXME: if dynamic config can delete overlays or
  				 * databases we'll have to check for cleanup here.
  				 * Currently it's not an issue because there are
  				 * no dynamic config deletes...
  				 */
  				if ( slapd_shutdown )
  					return SLAPD_ABANDON;
  
  				if ( !ldap_pvt_thread_pool_pausewait( &connection_pool ))
  					ldap_pvt_thread_yield();
  				ldap_pvt_thread_mutex_lock( &mt->mt_mutex );
  
  				/* clean up if the caller is giving up */
  				if ( op->o_abandon ) {
  					modinst **m2;
  					slap_callback **sc;
  					for (m2 = &mt->mt_mods; ; m2 = &(*m2)->mi_next) {
  						if ( *m2 == mi ) {
  							*m2 = mi->mi_next;
  							if ( mt->mt_tail == mi )
  								mt->mt_tail = ( m2 == &mt->mt_mods ) ? NULL : (modinst *)m2;
  							break;
  						}
  					}
  					for (sc = &op->o_callback; ; sc = &(*sc)->sc_next) {
  						if ( *sc == cb ) {
  							*sc = cb->sc_next;
  							break;
  						}
  					}
  					op->o_tmpfree( cb, op->o_tmpmemctx );
  					ldap_pvt_thread_mutex_unlock( &mt->mt_mutex );
  					return SLAPD_ABANDON;
  				}
  			}
  			ldap_pvt_thread_mutex_unlock( &mt->mt_mutex );
  		} else {
  			/* Record that we're modifying this entry now */
  			mt = ch_malloc( sizeof(modtarget) );
  			mt->mt_mods = mi;
  			mt->mt_tail = mi;
  			ber_dupbv( &mt->mt_dn, &mi->mi_op->o_req_ndn );
  			ldap_pvt_thread_mutex_init( &mt->mt_mutex );
  			ldap_avl_insert( &si->si_mods, mt, sp_avl_cmp, ldap_avl_dup_error );
  			ldap_pvt_thread_mutex_unlock( &si->si_mods_mutex );
  		}
  		opc->smt = mt;
  	}
  
  	if (( have_psearches || si->si_logs ) && op->o_tag != LDAP_REQ_ADD )
  		syncprov_matchops( op, opc, 1 );
  
  	return SLAP_CB_CONTINUE;
  }
  
  static int
  syncprov_op_extended( Operation *op, SlapReply *rs )
  {
  	if ( exop_is_write( op ))
  		return syncprov_op_mod( op, rs );
  
  	return SLAP_CB_CONTINUE;
  }
  
  typedef struct searchstate {
  	slap_overinst *ss_on;
  	syncops *ss_so;
  	BerVarray ss_ctxcsn;
  	int *ss_sids;
  	int ss_numcsns;
  #define	SS_PRESENT	0x01
  #define	SS_CHANGED	0x02
  	int ss_flags;
  } searchstate;
  
  typedef struct SyncOperationBuffer {
  	Operation		sob_op;
  	Opheader		sob_hdr;
  	OpExtra			sob_oe;
  	AttributeName	sob_extra;	/* not always present */
  	/* Further data allocated here */
  } SyncOperationBuffer;
  
  static void
  syncprov_detach_op( Operation *op, syncops *so, slap_overinst *on )
  {
  	SyncOperationBuffer *sopbuf2;
  	Operation *op2;
  	int i, alen = 0;
  	size_t size;
  	char *ptr;
  	GroupAssertion *g1, *g2;
  
  	/* count the search attrs */
  	for (i=0; op->ors_attrs && !BER_BVISNULL( &op->ors_attrs[i].an_name ); i++) {
  		alen += op->ors_attrs[i].an_name.bv_len + 1;
  	}
  	/* Make a new copy of the operation */
  	size = offsetof( SyncOperationBuffer, sob_extra ) +
  		(i ? ( (i+1) * sizeof(AttributeName) + alen) : 0) +
  		op->o_req_dn.bv_len + 1 +
  		op->o_req_ndn.bv_len + 1 +
  		op->o_ndn.bv_len + 1 +
  		so->s_filterstr.bv_len + 1;
  	sopbuf2 = ch_calloc( 1, size );
  	op2 = &sopbuf2->sob_op;
  	op2->o_hdr = &sopbuf2->sob_hdr;
  	LDAP_SLIST_FIRST(&op2->o_extra) = &sopbuf2->sob_oe;
  
  	/* Copy the fields we care about explicitly, leave the rest alone */
  	*op2->o_hdr = *op->o_hdr;
  	op2->o_tag = op->o_tag;
  	op2->o_time = op->o_time;
  	op2->o_bd = on->on_info->oi_origdb;
  	op2->o_request = op->o_request;
  	op2->o_managedsait = op->o_managedsait;
  	LDAP_SLIST_FIRST(&op2->o_extra)->oe_key = on;
  	LDAP_SLIST_NEXT(LDAP_SLIST_FIRST(&op2->o_extra), oe_next) = NULL;
  
  	ptr = (char *) sopbuf2 + offsetof( SyncOperationBuffer, sob_extra );
  	if ( i ) {
  		op2->ors_attrs = (AttributeName *) ptr;
  		ptr = (char *) &op2->ors_attrs[i+1];
  		for (i=0; !BER_BVISNULL( &op->ors_attrs[i].an_name ); i++) {
  			op2->ors_attrs[i] = op->ors_attrs[i];
  			op2->ors_attrs[i].an_name.bv_val = ptr;
  			ptr = lutil_strcopy( ptr, op->ors_attrs[i].an_name.bv_val ) + 1;
  		}
  		BER_BVZERO( &op2->ors_attrs[i].an_name );
  	}
  
  	op2->o_authz = op->o_authz;
  	op2->o_ndn.bv_val = ptr;
  	ptr = lutil_strcopy(ptr, op->o_ndn.bv_val) + 1;
  	op2->o_dn = op2->o_ndn;
  	op2->o_req_dn.bv_len = op->o_req_dn.bv_len;
  	op2->o_req_dn.bv_val = ptr;
  	ptr = lutil_strcopy(ptr, op->o_req_dn.bv_val) + 1;
  	op2->o_req_ndn.bv_len = op->o_req_ndn.bv_len;
  	op2->o_req_ndn.bv_val = ptr;
  	ptr = lutil_strcopy(ptr, op->o_req_ndn.bv_val) + 1;
  	op2->ors_filterstr.bv_val = ptr;
  	strcpy( ptr, so->s_filterstr.bv_val );
  	op2->ors_filterstr.bv_len = so->s_filterstr.bv_len;
  
  	/* Skip the AND/GE clause that we stuck on in front */
  	if ( so->s_flags & PS_FIX_FILTER ) {
  		op2->ors_filter = op->ors_filter->f_and->f_next;
  		so->s_flags ^= PS_FIX_FILTER;
  	} else {
  		op2->ors_filter = op->ors_filter;
  	}
  	op2->ors_filter = filter_dup( op2->ors_filter, NULL );
  	so->s_op = op2;
  
  	/* Copy any cached group ACLs individually */
  	op2->o_groups = NULL;
  	for ( g1=op->o_groups; g1; g1=g1->ga_next ) {
  		g2 = ch_malloc( sizeof(GroupAssertion) + g1->ga_len );
  		*g2 = *g1;
  		strcpy( g2->ga_ndn, g1->ga_ndn );
  		g2->ga_next = op2->o_groups;
  		op2->o_groups = g2;
  	}
  	/* Don't allow any further group caching */
  	op2->o_do_not_cache = 1;
  
  	/* Add op2 to conn so abandon will find us */
  	op->o_conn->c_n_ops_executing++;
  	op->o_conn->c_n_ops_completed--;
  	LDAP_STAILQ_INSERT_TAIL( &op->o_conn->c_ops, op2, o_next );
  	so->s_flags |= PS_IS_DETACHED;
  }
  
  static int
  syncprov_search_response( Operation *op, SlapReply *rs )
  {
  	searchstate *ss = op->o_callback->sc_private;
  	slap_overinst *on = ss->ss_on;
  	syncprov_info_t *si = (syncprov_info_t *)on->on_bi.bi_private;
  	sync_control *srs = op->o_controls[slap_cids.sc_LDAPsync];
  
  	if ( rs->sr_type == REP_SEARCH || rs->sr_type == REP_SEARCHREF ) {
  		Attribute *a;
  		/* If we got a referral without a referral object, there's
  		 * something missing that we cannot replicate. Just ignore it.
  		 * The consumer will abort because we didn't send the expected
  		 * control.
  		 */
  		if ( !rs->sr_entry ) {
  			assert( rs->sr_entry != NULL );
  			Debug( LDAP_DEBUG_ANY, "%s syncprov_search_response: "
  				"bogus referral in context\n", op->o_log_prefix );
  			return SLAP_CB_CONTINUE;
  		}
  		if ( is_entry_glue( rs->sr_entry ) ) {
  			return LDAP_SUCCESS;
  		}
  		a = attr_find( rs->sr_entry->e_attrs, slap_schema.si_ad_entryCSN );
  		if ( a == NULL && rs->sr_operational_attrs != NULL ) {
  			a = attr_find( rs->sr_operational_attrs, slap_schema.si_ad_entryCSN );
  		}
  		if ( a ) {
  			int i, sid;
  			sid = slap_parse_csn_sid( &a->a_nvals[0] );
  
  			/* If not a persistent search */
  			if ( !ss->ss_so ) {
  				/* Make sure entry is less than the snapshot'd contextCSN */
  				for ( i=0; i<ss->ss_numcsns; i++ ) {
  					if ( sid == ss->ss_sids[i] && ber_bvcmp( &a->a_nvals[0],
  						&ss->ss_ctxcsn[i] ) > 0 ) {
  						Debug( LDAP_DEBUG_SYNC, "%s syncprov_search_response: "
  							"Entry %s CSN %s greater than snapshot %s\n",
  							op->o_log_prefix,
  							rs->sr_entry->e_name.bv_val,
  							a->a_nvals[0].bv_val,
  							ss->ss_ctxcsn[i].bv_val );
  						return LDAP_SUCCESS;
  					}
  				}
  			}
  
  			/* Don't send old entries twice */
  			if ( srs->sr_state.ctxcsn ) {
  				for ( i=0; i<srs->sr_state.numcsns; i++ ) {
  					if ( sid == srs->sr_state.sids[i] &&
  						ber_bvcmp( &a->a_nvals[0],
  							&srs->sr_state.ctxcsn[i] )<= 0 ) {
  						Debug( LDAP_DEBUG_SYNC, "%s syncprov_search_response: "
  							"Entry %s CSN %s older or equal to ctx %s\n",
  							op->o_log_prefix,
  							rs->sr_entry->e_name.bv_val,
  							a->a_nvals[0].bv_val,
  							srs->sr_state.ctxcsn[i].bv_val );
  						return LDAP_SUCCESS;
  					}
  				}
  			}
  		}
  		rs->sr_ctrls = op->o_tmpalloc( sizeof(LDAPControl *)*2,
  			op->o_tmpmemctx );
  		rs->sr_ctrls[1] = NULL;
  		rs->sr_flags |= REP_CTRLS_MUSTBEFREED;
  		/* If we're in delta-sync mode, always send a cookie */
  		if ( si->si_nopres && si->si_usehint && a ) {
  			struct berval cookie;
  			slap_compose_sync_cookie( op, &cookie, a->a_nvals, srs->sr_state.rid,
  					slap_serverID ? slap_serverID : -1, NULL );
  			rs->sr_err = syncprov_state_ctrl( op, rs, rs->sr_entry,
  				LDAP_SYNC_ADD, rs->sr_ctrls, 0, 1, &cookie );
  			op->o_tmpfree( cookie.bv_val, op->o_tmpmemctx );
  		} else {
  			rs->sr_err = syncprov_state_ctrl( op, rs, rs->sr_entry,
  				LDAP_SYNC_ADD, rs->sr_ctrls, 0, 0, NULL );
  		}
  	} else if ( rs->sr_type == REP_RESULT && rs->sr_err == LDAP_SUCCESS ) {
  		struct berval cookie = BER_BVNULL;
  
  		if ( ( ss->ss_flags & SS_CHANGED ) &&
  			ss->ss_ctxcsn && !BER_BVISNULL( &ss->ss_ctxcsn[0] )) {
  			slap_compose_sync_cookie( op, &cookie, ss->ss_ctxcsn,
  				srs->sr_state.rid,
  				slap_serverID ? slap_serverID : -1, NULL );
  
  			Debug( LDAP_DEBUG_SYNC, "%s syncprov_search_response: cookie=%s\n",
  				op->o_log_prefix, cookie.bv_val );
  		}
  
  		/* Is this a regular refresh?
  		 * Note: refresh never gets here if there were no changes
  		 */
  		if ( !ss->ss_so ) {
  			rs->sr_ctrls = op->o_tmpalloc( sizeof(LDAPControl *)*2,
  				op->o_tmpmemctx );
  			rs->sr_ctrls[1] = NULL;
  			rs->sr_flags |= REP_CTRLS_MUSTBEFREED;
  			rs->sr_err = syncprov_done_ctrl( op, rs, rs->sr_ctrls,
  				0, 1, &cookie, ( ss->ss_flags & SS_PRESENT ) ?  LDAP_SYNC_REFRESH_PRESENTS :
  					LDAP_SYNC_REFRESH_DELETES );
  			op->o_tmpfree( cookie.bv_val, op->o_tmpmemctx );
  		} else {
  		/* It's RefreshAndPersist, transition to Persist phase */
  			syncprov_sendinfo( op, rs, ( ss->ss_flags & SS_PRESENT ) ?
  				LDAP_TAG_SYNC_REFRESH_PRESENT : LDAP_TAG_SYNC_REFRESH_DELETE,
  				( ss->ss_flags & SS_CHANGED ) ? &cookie : NULL,
  				1, NULL, 0 );
  			if ( !BER_BVISNULL( &cookie ))
  				op->o_tmpfree( cookie.bv_val, op->o_tmpmemctx );
  
  			/* Detach this Op from frontend control */
  			ldap_pvt_thread_mutex_lock( &op->o_conn->c_mutex );
  
  			/* But not if this connection was closed along the way */
  			if ( op->o_abandon ) {
  				ldap_pvt_thread_mutex_unlock( &op->o_conn->c_mutex );
  				/* syncprov_ab_cleanup will free this syncop */
  				return SLAPD_ABANDON;
  
  			} else {
  				ldap_pvt_thread_mutex_lock( &ss->ss_so->s_mutex );
  				/* Turn off the refreshing flag */
  				ss->ss_so->s_flags ^= PS_IS_REFRESHING;
  
  				Debug( LDAP_DEBUG_SYNC, "%s syncprov_search_response: "
  					"detaching op\n", op->o_log_prefix );
  				syncprov_detach_op( op, ss->ss_so, on );
  
  				ldap_pvt_thread_mutex_unlock( &op->o_conn->c_mutex );
  
  				/* If there are queued responses, fire them off */
  				if ( ss->ss_so->s_res )
  					syncprov_qstart( ss->ss_so );
  				ldap_pvt_thread_mutex_unlock( &ss->ss_so->s_mutex );
  				return SLAPD_NO_REPLY;
  			}
  		}
  	}
  
  	return SLAP_CB_CONTINUE;
  }
  
  static int
  syncprov_op_search( Operation *op, SlapReply *rs )
  {
  	slap_overinst		*on = (slap_overinst *)op->o_bd->bd_info;
  	syncprov_info_t		*si = (syncprov_info_t *)on->on_bi.bi_private;
  	slap_callback	*cb;
  	int gotstate = 0, changed = 0, do_present = 0;
  	syncops *sop = NULL;
  	searchstate *ss;
  	sync_control *srs;
  	BerVarray ctxcsn;
  	int i, *sids, numcsns;
  	struct berval mincsn, maxcsn;
  	int minsid, maxsid;
  	int dirty = 0;
  
  	if ( !(op->o_sync_mode & SLAP_SYNC_REFRESH) ) return SLAP_CB_CONTINUE;
  
  	if ( op->ors_deref & LDAP_DEREF_SEARCHING ) {
  		send_ldap_error( op, rs, LDAP_PROTOCOL_ERROR, "illegal value for derefAliases" );
  		return rs->sr_err;
  	}
  
  	srs = op->o_controls[slap_cids.sc_LDAPsync];
  	Debug( LDAP_DEBUG_SYNC, "%s syncprov_op_search: "
  		"got a %ssearch with a cookie=%s\n",
  		op->o_log_prefix,
  		op->o_sync_mode & SLAP_SYNC_PERSIST ? "persistent ": "",
  		srs->sr_state.octet_str.bv_val );
  
  	/* If this is a persistent search, set it up right away */
  	if ( op->o_sync_mode & SLAP_SYNC_PERSIST ) {
  		syncops so = {0};
  		fbase_cookie fc;
  		opcookie opc;
  		slap_callback sc = {0};
  
  		fc.fss = &so;
  		fc.fbase = 0;
  		so.s_eid = NOID;
  		so.s_op = op;
  		so.s_flags = PS_IS_REFRESHING | PS_FIND_BASE;
  		/* syncprov_findbase expects to be called as a callback... */
  		sc.sc_private = &opc;
  		opc.son = on;
  		ldap_pvt_thread_mutex_init( &so.s_mutex );
  		cb = op->o_callback;
  		op->o_callback = &sc;
  		rs->sr_err = syncprov_findbase( op, &fc );
  		op->o_callback = cb;
  		ldap_pvt_thread_mutex_destroy( &so.s_mutex );
  
  		/* Special case, if client knows nothing, nor do we, keep going */
  		if ( srs->sr_state.numcsns == 0 && rs->sr_err == LDAP_NO_SUCH_OBJECT ) {
  			Debug( LDAP_DEBUG_SYNC, "%s syncprov_op_search: "
  					"both our DB and client empty, ignoring NO_SUCH_OBJECT\n",
  					op->o_log_prefix );
  			rs->sr_err = LDAP_SUCCESS;
  		}
  
  		if ( rs->sr_err != LDAP_SUCCESS ) {
  			send_ldap_result( op, rs );
  			return rs->sr_err;
  		}
  		sop = ch_malloc( sizeof( syncops ));
  		*sop = so;
  		sop->s_rid = srs->sr_state.rid;
  		sop->s_sid = srs->sr_state.sid;
  		/* set refcount=2 to prevent being freed out from under us
  		 * by abandons that occur while we're running here
  		 */
  		sop->s_inuse = 2;
  
  		ldap_pvt_thread_mutex_lock( &si->si_ops_mutex );
  		while ( si->si_active ) {
  			/* Wait for active mods to finish before proceeding, as they
  			 * may already have inspected the si_ops list looking for
  			 * consumers to replicate the change to.  Using the log
  			 * doesn't help, as we may finish playing it before the
  			 * active mods gets added to it.
  			 */
  			ldap_pvt_thread_mutex_unlock( &si->si_ops_mutex );
  			if ( slapd_shutdown ) {
  				ch_free( sop );
  				return SLAPD_ABANDON;
  			}
  			if ( !ldap_pvt_thread_pool_pausewait( &connection_pool ))
  				ldap_pvt_thread_yield();
  			ldap_pvt_thread_mutex_lock( &si->si_ops_mutex );
  		}
  		if ( op->o_abandon ) {
  			ldap_pvt_thread_mutex_unlock( &si->si_ops_mutex );
  			ch_free( sop );
  			return SLAPD_ABANDON;
  		}
  		ldap_pvt_thread_mutex_init( &sop->s_mutex );
  		sop->s_next = si->si_ops;
  		sop->s_si = si;
  		si->si_ops = sop;
  		ldap_pvt_thread_mutex_unlock( &si->si_ops_mutex );
  		Debug( LDAP_DEBUG_SYNC, "%s syncprov_op_search: "
  			"registered persistent search\n", op->o_log_prefix );
  	}
  
  	/* snapshot the ctxcsn
  	 * Note: this must not be done before the psearch setup. (ITS#8365)
  	 */
  	ldap_pvt_thread_rdwr_rlock( &si->si_csn_rwlock );
  	numcsns = si->si_numcsns;
  	if ( numcsns ) {
  		ber_bvarray_dup_x( &ctxcsn, si->si_ctxcsn, op->o_tmpmemctx );
  		sids = op->o_tmpalloc( numcsns * sizeof(int), op->o_tmpmemctx );
  		for ( i=0; i<numcsns; i++ )
  			sids[i] = si->si_sids[i];
  	} else {
  		ctxcsn = NULL;
  		sids = NULL;
  	}
  	dirty = si->si_dirty;
  	ldap_pvt_thread_rdwr_runlock( &si->si_csn_rwlock );
  
  	/* If we have a cookie, handle the PRESENT lookups */
  	if ( srs->sr_state.ctxcsn ) {
  		sessionlog *sl;
  		int i, j;
  
  		/* If we don't have any CSN of our own yet, bail out.
  		 */
  		if ( !numcsns ) {
  			rs->sr_err = LDAP_UNWILLING_TO_PERFORM;
  			rs->sr_text = "consumer has state info but provider doesn't!";
  			goto bailout;
  		}
  
  		if ( !si->si_nopres )
  			do_present = SS_PRESENT;
  
  		/* If there are SIDs we don't recognize in the cookie, drop them */
  		for (i=0; i<srs->sr_state.numcsns; ) {
  			for (j=i; j<numcsns; j++) {
  				if ( srs->sr_state.sids[i] <= sids[j] ) {
  					break;
  				}
  			}
  			/* not found */
  			if ( j == numcsns || srs->sr_state.sids[i] != sids[j] ) {
  				char *tmp = srs->sr_state.ctxcsn[i].bv_val;
  				srs->sr_state.numcsns--;
  				for ( j=i; j<srs->sr_state.numcsns; j++ ) {
  					srs->sr_state.ctxcsn[j] = srs->sr_state.ctxcsn[j+1];
  					srs->sr_state.sids[j] = srs->sr_state.sids[j+1];
  				}
  				srs->sr_state.ctxcsn[j].bv_val = tmp;
  				srs->sr_state.ctxcsn[j].bv_len = 0;
  				continue;
  			}
  			i++;
  		}
  
  		if (srs->sr_state.numcsns != numcsns) {
  			/* consumer doesn't have the right number of CSNs */
  			Debug( LDAP_DEBUG_SYNC, "%s syncprov_op_search: "
  				"consumer cookie is missing a csn we track%s\n",
  				op->o_log_prefix, si->si_nopres ? ", rejecting" : "" );
  
  			if ( si->si_nopres ) {
  				rs->sr_err = LDAP_SYNC_REFRESH_REQUIRED;
  				rs->sr_text = "not enough information to resync, please use other means";
  				goto bailout;
  			}
  
  			changed = SS_CHANGED;
  			if ( srs->sr_state.ctxcsn ) {
  				ber_bvarray_free_x( srs->sr_state.ctxcsn, op->o_tmpmemctx );
  				srs->sr_state.ctxcsn = NULL;
  			}
  			if ( srs->sr_state.sids ) {
  				slap_sl_free( srs->sr_state.sids, op->o_tmpmemctx );
  				srs->sr_state.sids = NULL;
  			}
  			srs->sr_state.numcsns = 0;
  			goto shortcut;
  		}
  
  		/* Find the smallest CSN which differs from contextCSN */
  		mincsn.bv_len = 0;
  		maxcsn.bv_len = 0;
  		for ( i=0,j=0; i<srs->sr_state.numcsns; i++ ) {
  			int newer;
  			while ( srs->sr_state.sids[i] != sids[j] ) j++;
  			if ( BER_BVISEMPTY( &maxcsn ) || ber_bvcmp( &maxcsn,
  				&srs->sr_state.ctxcsn[i] ) < 0 ) {
  				maxcsn = srs->sr_state.ctxcsn[i];
  				maxsid = sids[j];
  			}
  			newer = ber_bvcmp( &srs->sr_state.ctxcsn[i], &ctxcsn[j] );
  			/* If our state is newer, tell consumer about changes */
  			if ( newer < 0) {
  				changed = SS_CHANGED;
  				if ( BER_BVISEMPTY( &mincsn ) || ber_bvcmp( &mincsn,
  					&srs->sr_state.ctxcsn[i] ) > 0 ) {
  					mincsn = srs->sr_state.ctxcsn[i];
  					minsid = sids[j];
  				}
  			} else if ( newer > 0 && sids[j] == slap_serverID ) {
  			/* our state is older, complain to consumer */
  				rs->sr_err = LDAP_UNWILLING_TO_PERFORM;
  				rs->sr_text = "consumer state is newer than provider!";
  				Debug( LDAP_DEBUG_SYNC, "%s syncprov_op_search: "
  					"consumer %d state %s is newer than provider %d state %s\n",
  					op->o_log_prefix, sids[i], srs->sr_state.ctxcsn[i].bv_val,
  					sids[j], /* == slap_serverID */
  					ctxcsn[j].bv_val);
  bailout:
  				if ( sop ) {
  					syncops **sp = &si->si_ops;
  
  					ldap_pvt_thread_mutex_lock( &si->si_ops_mutex );
  					while ( *sp != sop )
  						sp = &(*sp)->s_next;
  					*sp = sop->s_next;
  					ldap_pvt_thread_mutex_unlock( &si->si_ops_mutex );
  					ch_free( sop );
  				}
  				rs->sr_ctrls = NULL;
  				send_ldap_result( op, rs );
  				return rs->sr_err;
  			}
  		}
  		if ( BER_BVISEMPTY( &mincsn )) {
  			mincsn = maxcsn;
  			minsid = maxsid;
  		}
  
  		/* If nothing has changed, shortcut it */
  		if ( !changed && !dirty ) {
  			do_present = 0;
  no_change:	if ( !(op->o_sync_mode & SLAP_SYNC_PERSIST) ) {
  				LDAPControl	*ctrls[2];
  
  				ctrls[0] = NULL;
  				ctrls[1] = NULL;
  				syncprov_done_ctrl( op, rs, ctrls, 0, 0,
  					NULL, LDAP_SYNC_REFRESH_DELETES );
  				rs->sr_ctrls = ctrls;
  				rs->sr_err = LDAP_SUCCESS;
  				send_ldap_result( op, rs );
  				rs->sr_ctrls = NULL;
  				return rs->sr_err;
  			}
  			Debug( LDAP_DEBUG_SYNC, "%s syncprov_op_search: "
  				"no change, skipping log replay\n",
  				op->o_log_prefix );
  			goto shortcut;
  		}
  
  		if ( !BER_BVISNULL( &si->si_logbase ) ) {
  			do_present = 0;
  			if ( syncprov_play_accesslog( op, rs, srs, ctxcsn,
  					numcsns, sids, &mincsn, minsid ) ) {
  				do_present = SS_PRESENT;
  			}
  		} else if ( si->si_logs ) {
  			do_present = 0;
  			if ( syncprov_play_sessionlog( op, rs, srs, ctxcsn,
  					numcsns, sids, &mincsn, minsid ) ) {
  				do_present = SS_PRESENT;
  			}
  		}
  		/*
  		 * If sessionlog wasn't useful, see if we can find at least one entry
  		 * that hasn't changed based on the cookie.
  		 *
  		 * TODO: Using mincsn only (rather than the whole cookie) will
  		 * under-approximate the set of entries that haven't changed, but we
  		 * can't look up CSNs by serverid with the current indexing support.
  		 *
  		 * As a result, dormant serverids in the cluster become mincsns and
  		 * more likely to make syncprov_findcsn(,FIND_CSN,) fail -> triggering
  		 * an expensive refresh...
  		 */
  		if ( !do_present ) {
  			gotstate = 1;
  		} else if ( syncprov_findcsn( op, FIND_CSN, &mincsn ) != LDAP_SUCCESS ) {
  			/* No, so a reload is required */
  			/* the 2.2 consumer doesn't send this hint */
  			if ( si->si_usehint && srs->sr_rhint == 0 ) {
  				if ( ctxcsn )
  					ber_bvarray_free_x( ctxcsn, op->o_tmpmemctx );
  				if ( sids )
  					op->o_tmpfree( sids, op->o_tmpmemctx );
  				rs->sr_err = LDAP_SYNC_REFRESH_REQUIRED;
  				rs->sr_text = "sync cookie is stale";
  				goto bailout;
  			}
  			Debug( LDAP_DEBUG_SYNC, "%s syncprov_op_search: "
  				"failed to find entry with csn=%s, ignoring cookie\n",
  				op->o_log_prefix, mincsn.bv_val );
  			if ( srs->sr_state.ctxcsn ) {
  				ber_bvarray_free_x( srs->sr_state.ctxcsn, op->o_tmpmemctx );
  				srs->sr_state.ctxcsn = NULL;
  			}
  			if ( srs->sr_state.sids ) {
  				slap_sl_free( srs->sr_state.sids, op->o_tmpmemctx );
  				srs->sr_state.sids = NULL;
  			}
  			srs->sr_state.numcsns = 0;
  		} else {
  			gotstate = 1;
  			/* If changed and doing Present lookup, send Present UUIDs */
  			if ( syncprov_findcsn( op, FIND_PRESENT, 0 ) != LDAP_SUCCESS ) {
  				if ( ctxcsn )
  					ber_bvarray_free_x( ctxcsn, op->o_tmpmemctx );
  				if ( sids )
  					op->o_tmpfree( sids, op->o_tmpmemctx );
  				goto bailout;
  			}
  		}
  	} else {
  		/* The consumer knows nothing, we know nothing. OK. */
  		if (!numcsns)
  			goto no_change;
  		/* No consumer state, assume something has changed */
  		changed = SS_CHANGED;
  	}
  
  shortcut:
  	/* Append CSN range to search filter, save original filter
  	 * for persistent search evaluation
  	 */
  	if ( sop ) {
  		ldap_pvt_thread_mutex_lock( &sop->s_mutex );
  		sop->s_filterstr = op->ors_filterstr;
  		/* correct the refcount that was set to 2 before */
  		sop->s_inuse--;
  	}
  
  	/* If something changed, find the changes */
  	if ( gotstate && ( changed || dirty ) ) {
  		Filter *fand, *fava;
  
  		fand = op->o_tmpalloc( sizeof(Filter), op->o_tmpmemctx );
  		fand->f_choice = LDAP_FILTER_AND;
  		fand->f_next = NULL;
  		fava = op->o_tmpalloc( sizeof(Filter), op->o_tmpmemctx );
  		fand->f_and = fava;
  		fava->f_choice = LDAP_FILTER_GE;
  		fava->f_ava = op->o_tmpalloc( sizeof(AttributeAssertion), op->o_tmpmemctx );
  		fava->f_ava->aa_desc = slap_schema.si_ad_entryCSN;
  #ifdef LDAP_COMP_MATCH
  		fava->f_ava->aa_cf = NULL;
  #endif
  		ber_dupbv_x( &fava->f_ava->aa_value, &mincsn, op->o_tmpmemctx );
  		fava->f_next = op->ors_filter;
  		op->ors_filter = fand;
  		filter2bv_x( op, op->ors_filter, &op->ors_filterstr );
  		if ( sop ) {
  			sop->s_flags |= PS_FIX_FILTER;
  		}
  	}
  	if ( sop ) {
  		ldap_pvt_thread_mutex_unlock( &sop->s_mutex );
  	}
  
  	/* Let our callback add needed info to returned entries */
  	cb = op->o_tmpcalloc(1, sizeof(slap_callback)+sizeof(searchstate), op->o_tmpmemctx);
  	ss = (searchstate *)(cb+1);
  	ss->ss_on = on;
  	ss->ss_so = sop;
  	ss->ss_flags = do_present | changed;
  	ss->ss_ctxcsn = ctxcsn;
  	ss->ss_numcsns = numcsns;
  	ss->ss_sids = sids;
  	cb->sc_response = syncprov_search_response;
  	cb->sc_private = ss;
  	cb->sc_next = op->o_callback;
  	op->o_callback = cb;
  
  	/* If this is a persistent search and no changes were reported during
  	 * the refresh phase, just invoke the response callback to transition
  	 * us into persist phase
  	 */
  	if ( !changed && !dirty ) {
  		Debug( LDAP_DEBUG_SYNC, "%s syncprov_op_search: "
  			"nothing changed, finishing up initial search early\n",
  			op->o_log_prefix );
  		rs->sr_err = LDAP_SUCCESS;
  		rs->sr_nentries = 0;
  		send_ldap_result( op, rs );
  		return rs->sr_err;
  	}
  	return SLAP_CB_CONTINUE;
  }
  
  static int
  syncprov_operational(
  	Operation *op,
  	SlapReply *rs )
  {
  	slap_overinst		*on = (slap_overinst *)op->o_bd->bd_info;
  	syncprov_info_t		*si = (syncprov_info_t *)on->on_bi.bi_private;
  
  	/* This prevents generating unnecessarily; frontend will strip
  	 * any statically stored copy.
  	 */
  	if ( op->o_sync != SLAP_CONTROL_NONE )
  		return SLAP_CB_CONTINUE;
  
  	if ( rs->sr_entry &&
  		dn_match( &rs->sr_entry->e_nname, &si->si_contextdn )) {
  
  		if ( SLAP_OPATTRS( rs->sr_attr_flags ) ||
  			ad_inlist( slap_schema.si_ad_contextCSN, rs->sr_attrs )) {
  			Attribute *a, **ap = NULL;
  
  			for ( a=rs->sr_entry->e_attrs; a; a=a->a_next ) {
  				if ( a->a_desc == slap_schema.si_ad_contextCSN )
  					break;
  			}
  
  			ldap_pvt_thread_rdwr_rlock( &si->si_csn_rwlock );
  			if ( si->si_ctxcsn ) {
  				if ( !a ) {
  					for ( ap = &rs->sr_operational_attrs; *ap;
  						ap=&(*ap)->a_next );
  
  					a = attr_alloc( slap_schema.si_ad_contextCSN );
  					*ap = a;
  				}
  
  				if ( !ap ) {
  					if ( rs_entry2modifiable( op, rs, on )) {
  						a = attr_find( rs->sr_entry->e_attrs,
  							slap_schema.si_ad_contextCSN );
  					}
  					if ( a->a_nvals != a->a_vals ) {
  						ber_bvarray_free( a->a_nvals );
  					}
  					a->a_nvals = NULL;
  					ber_bvarray_free( a->a_vals );
  					a->a_vals = NULL;
  					a->a_numvals = 0;
  				}
  				attr_valadd( a, si->si_ctxcsn, si->si_ctxcsn, si->si_numcsns );
  			}
  			ldap_pvt_thread_rdwr_runlock( &si->si_csn_rwlock );
  		}
  	}
  	return SLAP_CB_CONTINUE;
  }
  
  static int
  syncprov_setup_accesslog(void)
  {
  	const char *text;
  	int rc = -1;
  
  	if ( !ad_reqType ) {
  		if ( slap_str2ad( "reqType", &ad_reqType, &text ) ) {
  			Debug( LDAP_DEBUG_ANY, "syncprov_setup_accesslog: "
  					"couldn't get definition for attribute reqType, "
  					"is accessslog configured?\n" );
  			return rc;
  		}
  	}
  
  	if ( !ad_reqResult ) {
  		if ( slap_str2ad( "reqResult", &ad_reqResult, &text ) ) {
  			Debug( LDAP_DEBUG_ANY, "syncprov_setup_accesslog: "
  					"couldn't get definition for attribute reqResult, "
  					"is accessslog configured?\n" );
  			return rc;
  		}
  	}
  
  	if ( !ad_reqDN ) {
  		if ( slap_str2ad( "reqDN", &ad_reqDN, &text ) ) {
  			Debug( LDAP_DEBUG_ANY, "syncprov_setup_accesslog: "
  					"couldn't get definition for attribute reqDN, "
  					"is accessslog configured?\n" );
  			return rc;
  		}
  	}
  
  	if ( !ad_reqEntryUUID ) {
  		if ( slap_str2ad( "reqEntryUUID", &ad_reqEntryUUID, &text ) ) {
  			Debug( LDAP_DEBUG_ANY, "syncprov_setup_accesslog: "
  					"couldn't get definition for attribute reqEntryUUID, "
  					"is accessslog configured?\n" );
  			return rc;
  		}
  	}
  
  	if ( !ad_reqNewDN ) {
  		if ( slap_str2ad( "reqNewDN", &ad_reqNewDN, &text ) ) {
  			Debug( LDAP_DEBUG_ANY, "syncprov_setup_accesslog: "
  					"couldn't get definition for attribute reqNewDN, "
  					"is accessslog configured?\n" );
  			return rc;
  		}
  	}
  
  	if ( !ad_minCSN ) {
  		if ( slap_str2ad( "minCSN", &ad_minCSN, &text ) ) {
  			Debug( LDAP_DEBUG_ANY, "syncprov_setup_accesslog: "
  					"couldn't get definition for attribute minCSN, "
  					"is accessslog configured?\n" );
  			return rc;
  		}
  	}
  
  	return LDAP_SUCCESS;
  }
  
  enum {
  	SP_CHKPT = 1,
  	SP_SESSL,
  	SP_NOPRES,
  	SP_USEHINT,
  	SP_LOGDB
  };
  
  static ConfigDriver sp_cf_gen;
  
  static ConfigTable spcfg[] = {
  	{ "syncprov-checkpoint", "ops> <minutes", 3, 3, 0, ARG_MAGIC|SP_CHKPT,
  		sp_cf_gen, "( OLcfgOvAt:1.1 NAME 'olcSpCheckpoint' "
  			"DESC 'ContextCSN checkpoint interval in ops and minutes' "
  			"EQUALITY caseIgnoreMatch "
  			"SYNTAX OMsDirectoryString SINGLE-VALUE )", NULL, NULL },
  	{ "syncprov-sessionlog", "ops", 2, 2, 0, ARG_INT|ARG_MAGIC|SP_SESSL,
  		sp_cf_gen, "( OLcfgOvAt:1.2 NAME 'olcSpSessionlog' "
  			"DESC 'Session log size in ops' "
  			"EQUALITY integerMatch "
  			"SYNTAX OMsInteger SINGLE-VALUE )", NULL, NULL },
  	{ "syncprov-nopresent", NULL, 2, 2, 0, ARG_ON_OFF|ARG_MAGIC|SP_NOPRES,
  		sp_cf_gen, "( OLcfgOvAt:1.3 NAME 'olcSpNoPresent' "
  			"DESC 'Omit Present phase processing' "
  			"EQUALITY booleanMatch "
  			"SYNTAX OMsBoolean SINGLE-VALUE )", NULL, NULL },
  	{ "syncprov-reloadhint", NULL, 2, 2, 0, ARG_ON_OFF|ARG_MAGIC|SP_USEHINT,
  		sp_cf_gen, "( OLcfgOvAt:1.4 NAME 'olcSpReloadHint' "
  			"DESC 'Observe Reload Hint in Request control' "
  			"EQUALITY booleanMatch "
  			"SYNTAX OMsBoolean SINGLE-VALUE )", NULL, NULL },
  	{ "syncprov-sessionlog-source", NULL, 2, 2, 0, ARG_DN|ARG_QUOTE|ARG_MAGIC|SP_LOGDB,
  		sp_cf_gen, "( OLcfgOvAt:1.5 NAME 'olcSpSessionlogSource' "
  			"DESC 'On startup, try loading sessionlog from this subtree' "
  			"SYNTAX OMsDN SINGLE-VALUE )", NULL, NULL },
  	{ NULL, NULL, 0, 0, 0, ARG_IGNORED }
  };
  
  static ConfigOCs spocs[] = {
  	{ "( OLcfgOvOc:1.1 "
  		"NAME 'olcSyncProvConfig' "
  		"DESC 'SyncRepl Provider configuration' "
  		"SUP olcOverlayConfig "
  		"MAY ( olcSpCheckpoint "
  			"$ olcSpSessionlog "
  			"$ olcSpNoPresent "
  			"$ olcSpReloadHint "
  			"$ olcSpSessionlogSource "
  		") )",
  			Cft_Overlay, spcfg },
  	{ NULL, 0, NULL }
  };
  
  static int
  sp_cf_gen(ConfigArgs *c)
  {
  	slap_overinst		*on = (slap_overinst *)c->bi;
  	syncprov_info_t		*si = (syncprov_info_t *)on->on_bi.bi_private;
  	int rc = 0;
  
  	if ( c->op == SLAP_CONFIG_EMIT ) {
  		switch ( c->type ) {
  		case SP_CHKPT:
  			if ( si->si_chkops || si->si_chktime ) {
  				struct berval bv;
  				/* we assume si_chktime is a multiple of 60
  				 * because the parsed value was originally
  				 * multiplied by 60 */
  				bv.bv_len = snprintf( c->cr_msg, sizeof( c->cr_msg ),
  					"%d %d", si->si_chkops, si->si_chktime/60 );
  				if ( bv.bv_len >= sizeof( c->cr_msg ) ) {
  					rc = 1;
  				} else {
  					bv.bv_val = c->cr_msg;
  					value_add_one( &c->rvalue_vals, &bv );
  				}
  			} else {
  				rc = 1;
  			}
  			break;
  		case SP_SESSL:
  			if ( si->si_logs ) {
  				c->value_int = si->si_logs->sl_size;
  			} else {
  				rc = 1;
  			}
  			break;
  		case SP_NOPRES:
  			if ( si->si_nopres ) {
  				c->value_int = 1;
  			} else {
  				rc = 1;
  			}
  			break;
  		case SP_USEHINT:
  			if ( si->si_usehint ) {
  				c->value_int = 1;
  			} else {
  				rc = 1;
  			}
  			break;
  		case SP_LOGDB:
  			if ( BER_BVISEMPTY( &si->si_logbase ) ) {
  				rc = 1;
  			} else {
  				value_add_one( &c->rvalue_vals, &si->si_logbase );
  				value_add_one( &c->rvalue_nvals, &si->si_logbase );
  			}
  			break;
  		}
  		return rc;
  	} else if ( c->op == LDAP_MOD_DELETE ) {
  		switch ( c->type ) {
  		case SP_CHKPT:
  			si->si_chkops = 0;
  			si->si_chktime = 0;
  			break;
  		case SP_SESSL:
  			if ( si->si_logs )
  				si->si_logs->sl_size = 0;
  			break;
  		case SP_NOPRES:
  			si->si_nopres = 0;
  			break;
  		case SP_USEHINT:
  			si->si_usehint = 0;
  			break;
  		case SP_LOGDB:
  			if ( !BER_BVISNULL( &si->si_logbase ) ) {
  				ch_free( si->si_logbase.bv_val );
  				BER_BVZERO( &si->si_logbase );
  			}
  			break;
  		}
  		return rc;
  	}
  	switch ( c->type ) {
  	case SP_CHKPT:
  		if ( lutil_atoi( &si->si_chkops, c->argv[1] ) != 0 ) {
  			snprintf( c->cr_msg, sizeof( c->cr_msg ), "%s unable to parse checkpoint ops # \"%s\"",
  				c->argv[0], c->argv[1] );
  			Debug( LDAP_DEBUG_CONFIG|LDAP_DEBUG_NONE,
  				"%s: %s\n", c->log, c->cr_msg );
  			return ARG_BAD_CONF;
  		}
  		if ( si->si_chkops <= 0 ) {
  			snprintf( c->cr_msg, sizeof( c->cr_msg ), "%s invalid checkpoint ops # \"%d\"",
  				c->argv[0], si->si_chkops );
  			Debug( LDAP_DEBUG_CONFIG|LDAP_DEBUG_NONE,
  				"%s: %s\n", c->log, c->cr_msg );
  			return ARG_BAD_CONF;
  		}
  		if ( lutil_atoi( &si->si_chktime, c->argv[2] ) != 0 ) {
  			snprintf( c->cr_msg, sizeof( c->cr_msg ), "%s unable to parse checkpoint time \"%s\"",
  				c->argv[0], c->argv[1] );
  			Debug( LDAP_DEBUG_CONFIG|LDAP_DEBUG_NONE,
  				"%s: %s\n", c->log, c->cr_msg );
  			return ARG_BAD_CONF;
  		}
  		if ( si->si_chktime <= 0 ) {
  			snprintf( c->cr_msg, sizeof( c->cr_msg ), "%s invalid checkpoint time \"%d\"",
  				c->argv[0], si->si_chkops );
  			Debug( LDAP_DEBUG_CONFIG|LDAP_DEBUG_NONE,
  				"%s: %s\n", c->log, c->cr_msg );
  			return ARG_BAD_CONF;
  		}
  		si->si_chktime *= 60;
  		break;
  	case SP_SESSL: {
  		sessionlog *sl;
  		int size = c->value_int;
  
  		if ( size < 0 ) {
  			snprintf( c->cr_msg, sizeof( c->cr_msg ), "%s size %d is negative",
  				c->argv[0], size );
  			Debug( LDAP_DEBUG_CONFIG|LDAP_DEBUG_NONE,
  				"%s: %s\n", c->log, c->cr_msg );
  			return ARG_BAD_CONF;
  		}
  		if ( size && !BER_BVISNULL( &si->si_logbase ) ) {
  			Debug( LDAP_DEBUG_ANY, "syncprov_config: while configuring "
  					"internal sessionlog, accesslog source has already been "
  					"configured, this results in wasteful operation\n" );
  		}
  		sl = si->si_logs;
  		if ( !sl ) {
  			if ( !size ) break;
  			sl = ch_calloc( 1, sizeof( sessionlog ));
  			ldap_pvt_thread_rdwr_init( &sl->sl_mutex );
  			si->si_logs = sl;
  		}
  		sl->sl_size = size;
  		}
  		break;
  	case SP_NOPRES:
  		si->si_nopres = c->value_int;
  		break;
  	case SP_USEHINT:
  		si->si_usehint = c->value_int;
  		break;
  	case SP_LOGDB:
  		if ( si->si_logs ) {
  			Debug( LDAP_DEBUG_ANY, "syncprov_config: while configuring "
  					"accesslog source, internal sessionlog has already been "
  					"configured, this results in wasteful operation\n" );
  		}
  		if ( CONFIG_ONLINE_ADD( c ) ) {
  			if ( !select_backend( &c->value_ndn, 0 ) ) {
  				snprintf( c->cr_msg, sizeof( c->cr_msg ),
  					"<%s> no matching backend found for suffix",
  					c->argv[0] );
  				Debug( LDAP_DEBUG_ANY, "%s: %s \"%s\"\n",
  					c->log, c->cr_msg, c->value_dn.bv_val );
  				rc = 1;
  				break;
  			}
  			ch_free( c->value_ndn.bv_val );
  		}
  		si->si_logbase = c->value_ndn;
  		rc = syncprov_setup_accesslog();
  		ch_free( c->value_dn.bv_val );
  		break;
  	}
  	return rc;
  }
  
  /* ITS#3456 we cannot run this search on the main thread, must use a
   * child thread in order to insure we have a big enough stack.
   */
  static void *
  syncprov_db_otask(
  	void *ptr
  )
  {
  	syncprov_findcsn( ptr, FIND_MAXCSN, 0 );
  	return NULL;
  }
  
  static int
  syncprov_db_ocallback(
  	Operation *op,
  	SlapReply *rs
  )
  {
  	if ( rs->sr_type == REP_SEARCH && rs->sr_err == LDAP_SUCCESS ) {
  		if ( rs->sr_entry->e_name.bv_len )
  			op->o_callback->sc_private = (void *)1;
  	}
  	return LDAP_SUCCESS;
  }
  
  /* ITS#9015 see if the DB is really empty */
  static void *
  syncprov_db_otask2(
  	void *ptr
  )
  {
  	Operation *op = ptr;
  	SlapReply rs = {REP_RESULT};
  	slap_callback cb = {0};
  	int rc;
  
  	cb.sc_response = syncprov_db_ocallback;
  
  	op->o_managedsait = SLAP_CONTROL_CRITICAL;
  	op->o_callback = &cb;
  	op->o_tag = LDAP_REQ_SEARCH;
  	op->ors_scope = LDAP_SCOPE_SUBTREE;
  	op->ors_limit = NULL;
  	op->ors_slimit = 1;
  	op->ors_tlimit = SLAP_NO_LIMIT;
  	op->ors_attrs = slap_anlist_no_attrs;
  	op->ors_attrsonly = 1;
  	op->ors_deref = LDAP_DEREF_NEVER;
  	op->ors_filter = &generic_filter;
  	op->ors_filterstr = generic_filterstr;
  	rc = op->o_bd->be_search( op, &rs );
  	if ( rc == LDAP_SIZELIMIT_EXCEEDED || cb.sc_private )
  		op->ors_slimit = 2;
  	return NULL;
  }
  
  /* Read any existing contextCSN from the underlying db.
   * Then search for any entries newer than that. If no value exists,
   * just generate it. Cache whatever result.
   */
  static int
  syncprov_db_open(
  	BackendDB *be,
  	ConfigReply *cr
  )
  {
  	slap_overinst   *on = (slap_overinst *) be->bd_info;
  	syncprov_info_t *si = (syncprov_info_t *)on->on_bi.bi_private;
  
  	Connection conn = { 0 };
  	OperationBuffer opbuf;
  	Operation *op;
  	Entry *e = NULL;
  	Attribute *a;
  	int rc;
  	void *thrctx = NULL;
  
  	if ( !SLAP_LASTMOD( be )) {
  		Debug( LDAP_DEBUG_ANY,
  			"syncprov_db_open: invalid config, lastmod must be enabled\n" );
  		return -1;
  	}
  
  	if ( slapMode & SLAP_TOOL_MODE ) {
  		return 0;
  	}
  
  	rc = overlay_register_control( be, LDAP_CONTROL_SYNC );
  	if ( rc ) {
  		return rc;
  	}
  
  	Debug( LDAP_DEBUG_SYNC, "syncprov_db_open: "
  		"starting syncprov for suffix %s\n",
  		be->be_suffix[0].bv_val );
  
  	thrctx = ldap_pvt_thread_pool_context();
  	connection_fake_init2( &conn, &opbuf, thrctx, 0 );
  	op = &opbuf.ob_op;
  	op->o_bd = be;
  	op->o_dn = be->be_rootdn;
  	op->o_ndn = be->be_rootndn;
  
  	if ( SLAP_SYNC_SUBENTRY( be )) {
  		build_new_dn( &si->si_contextdn, be->be_nsuffix,
  			(struct berval *)&slap_ldapsync_cn_bv, NULL );
  	} else {
  		si->si_contextdn = be->be_nsuffix[0];
  	}
  	rc = overlay_entry_get_ov( op, &si->si_contextdn, NULL,
  		slap_schema.si_ad_contextCSN, 0, &e, on );
  
  	if ( e ) {
  		ldap_pvt_thread_t tid;
  
  		a = attr_find( e->e_attrs, slap_schema.si_ad_contextCSN );
  		if ( a ) {
  			ber_bvarray_dup_x( &si->si_ctxcsn, a->a_vals, NULL );
  			si->si_numcsns = a->a_numvals;
  			si->si_sids = slap_parse_csn_sids( si->si_ctxcsn, a->a_numvals, NULL );
  			slap_sort_csn_sids( si->si_ctxcsn, si->si_sids, si->si_numcsns, NULL );
  		}
  		overlay_entry_release_ov( op, e, 0, on );
  		if ( si->si_ctxcsn && !SLAP_DBCLEAN( be )) {
  			op->o_tag = LDAP_REQ_SEARCH;
  			op->o_req_dn = be->be_suffix[0];
  			op->o_req_ndn = be->be_nsuffix[0];
  			op->ors_scope = LDAP_SCOPE_SUBTREE;
  			ldap_pvt_thread_create( &tid, 0, syncprov_db_otask, op );
  			ldap_pvt_thread_join( tid, NULL );
  		}
  	}
  
  	/* Didn't find a contextCSN, should we generate one? */
  	if ( !si->si_ctxcsn ) {
  		char csnbuf[ LDAP_PVT_CSNSTR_BUFSIZE ];
  		struct berval csn;
  
  		if ( SLAP_SINGLE_SHADOW( op->o_bd ) ) {
  			/* Not in charge of this serverID, don't generate anything. */
  			goto out;
  		}
  		if ( !SLAP_SYNC_SUBENTRY( be ) && rc != LDAP_SUCCESS
  				&& rc != LDAP_NO_SUCH_ATTRIBUTE ) {
  			/* If the DB is genuinely empty, don't generate one either. */
  			goto out;
  		}
  		if ( !si->si_contextdn.bv_len ) {
  			ldap_pvt_thread_t tid;
  			/* a glue entry here with no contextCSN might mean an empty DB.
  			 * we need to search for children, to be sure.
  			 */
  			op->o_req_dn = be->be_suffix[0];
  			op->o_req_ndn = be->be_nsuffix[0];
  			op->o_bd->bd_info = (BackendInfo *)on->on_info;
  			ldap_pvt_thread_create( &tid, 0, syncprov_db_otask2, op );
  			ldap_pvt_thread_join( tid, NULL );
  			if ( op->ors_slimit == 1 )
  				goto out;
  		}
  
  		csn.bv_val = csnbuf;
  		csn.bv_len = sizeof( csnbuf );
  		slap_get_csn( op, &csn, 0 );
  		value_add_one( &si->si_ctxcsn, &csn );
  		si->si_numcsns = 1;
  		si->si_sids = ch_malloc( sizeof(int) );
  		si->si_sids[0] = slap_serverID;
  		Debug( LDAP_DEBUG_SYNC, "syncprov_db_open: "
  			"generated a new ctxcsn=%s for suffix %s\n",
  			csn.bv_val, be->be_suffix[0].bv_val );
  
  		/* make sure we do a checkpoint on close */
  		si->si_numops++;
  	}
  
  	/* Initialize the sessionlog mincsn */
  	if ( si->si_logs && si->si_numcsns ) {
  		sessionlog *sl = si->si_logs;
  		int i;
  		ber_bvarray_dup_x( &sl->sl_mincsn, si->si_ctxcsn, NULL );
  		sl->sl_numcsns = si->si_numcsns;
  		sl->sl_sids = ch_malloc( si->si_numcsns * sizeof(int) );
  		for ( i=0; i < si->si_numcsns; i++ )
  			sl->sl_sids[i] = si->si_sids[i];
  	}
  
  	if ( !BER_BVISNULL( &si->si_logbase ) ) {
  		BackendDB *db = select_backend( &si->si_logbase, 0 );
  		if ( !db ) {
  			Debug( LDAP_DEBUG_ANY, "syncprov_db_open: "
  					"configured accesslog database dn='%s' not present\n",
  					si->si_logbase.bv_val );
  			return -1;
  		}
  	}
  
  out:
  	op->o_bd->bd_info = (BackendInfo *)on;
  	return 0;
  }
  
  /* Write the current contextCSN into the underlying db.
   */
  static int
  syncprov_db_close(
  	BackendDB *be,
  	ConfigReply *cr
  )
  {
  	slap_overinst   *on = (slap_overinst *) be->bd_info;
  	syncprov_info_t *si = (syncprov_info_t *)on->on_bi.bi_private;
  #ifdef SLAP_CONFIG_DELETE
  	syncops *so, *sonext;
  #endif /* SLAP_CONFIG_DELETE */
  
  	if ( slapMode & SLAP_TOOL_MODE ) {
  		return 0;
  	}
  	if ( si->si_numops ) {
  		Connection conn = {0};
  		OperationBuffer opbuf;
  		Operation *op;
  		void *thrctx;
  
  		thrctx = ldap_pvt_thread_pool_context();
  		connection_fake_init2( &conn, &opbuf, thrctx, 0 );
  		op = &opbuf.ob_op;
  		op->o_bd = be;
  		op->o_dn = be->be_rootdn;
  		op->o_ndn = be->be_rootndn;
  		syncprov_checkpoint( op, on );
  	}
  
  #ifdef SLAP_CONFIG_DELETE
  	if ( !slapd_shutdown ) {
  		ldap_pvt_thread_mutex_lock( &si->si_ops_mutex );
  		for ( so=si->si_ops, sonext=so;  so; so=sonext  ) {
  			SlapReply rs = {REP_RESULT};
  			rs.sr_err = LDAP_UNAVAILABLE;
  			ldap_pvt_thread_mutex_lock( &so->s_mutex );
  			send_ldap_result( so->s_op, &rs );
  			sonext=so->s_next;
  			if ( so->s_flags & PS_TASK_QUEUED )
  				ldap_pvt_thread_pool_retract( so->s_pool_cookie );
  			ldap_pvt_thread_mutex_unlock( &so->s_mutex );
  			if ( !syncprov_drop_psearch( so, 0 ))
  				so->s_si = NULL;
  		}
  		si->si_ops=NULL;
  		ldap_pvt_thread_mutex_unlock( &si->si_ops_mutex );
  	}
  	overlay_unregister_control( be, LDAP_CONTROL_SYNC );
  #endif /* SLAP_CONFIG_DELETE */
  
  	return 0;
  }
  
  static int
  syncprov_db_init(
  	BackendDB *be,
  	ConfigReply *cr
  )
  {
  	slap_overinst	*on = (slap_overinst *)be->bd_info;
  	syncprov_info_t	*si;
  
  	if ( SLAP_ISGLOBALOVERLAY( be ) ) {
  		Debug( LDAP_DEBUG_ANY,
  			"syncprov must be instantiated within a database.\n" );
  		return 1;
  	}
  
  	si = ch_calloc(1, sizeof(syncprov_info_t));
  	on->on_bi.bi_private = si;
  	ldap_pvt_thread_rdwr_init( &si->si_csn_rwlock );
  	ldap_pvt_thread_mutex_init( &si->si_ops_mutex );
  	ldap_pvt_thread_mutex_init( &si->si_mods_mutex );
  	ldap_pvt_thread_mutex_init( &si->si_resp_mutex );
  
  	csn_anlist[0].an_desc = slap_schema.si_ad_entryCSN;
  	csn_anlist[0].an_name = slap_schema.si_ad_entryCSN->ad_cname;
  	csn_anlist[1].an_desc = slap_schema.si_ad_entryUUID;
  	csn_anlist[1].an_name = slap_schema.si_ad_entryUUID->ad_cname;
  
  	uuid_anlist[0].an_desc = slap_schema.si_ad_entryUUID;
  	uuid_anlist[0].an_name = slap_schema.si_ad_entryUUID->ad_cname;
  
  	return 0;
  }
  
  static int
  syncprov_db_destroy(
  	BackendDB *be,
  	ConfigReply *cr
  )
  {
  	slap_overinst	*on = (slap_overinst *)be->bd_info;
  	syncprov_info_t	*si = (syncprov_info_t *)on->on_bi.bi_private;
  
  	if ( si ) {
  		if ( si->si_logs ) {
  			sessionlog *sl = si->si_logs;
  
  			ldap_tavl_free( sl->sl_entries, (AVL_FREE)ch_free );
  			if ( sl->sl_mincsn )
  				ber_bvarray_free( sl->sl_mincsn );
  			if ( sl->sl_sids )
  				ch_free( sl->sl_sids );
  
  			ldap_pvt_thread_rdwr_destroy(&si->si_logs->sl_mutex);
  			ch_free( si->si_logs );
  		}
  		if ( si->si_ctxcsn )
  			ber_bvarray_free( si->si_ctxcsn );
  		if ( si->si_sids )
  			ch_free( si->si_sids );
  		ldap_pvt_thread_mutex_destroy( &si->si_resp_mutex );
  		ldap_pvt_thread_mutex_destroy( &si->si_mods_mutex );
  		ldap_pvt_thread_mutex_destroy( &si->si_ops_mutex );
  		ldap_pvt_thread_rdwr_destroy( &si->si_csn_rwlock );
  		ch_free( si );
  	}
  
  	return 0;
  }
  
  static int syncprov_parseCtrl (
  	Operation *op,
  	SlapReply *rs,
  	LDAPControl *ctrl )
  {
  	ber_tag_t tag;
  	BerElementBuffer berbuf;
  	BerElement *ber = (BerElement *)&berbuf;
  	ber_int_t mode;
  	ber_len_t len;
  	struct berval cookie = BER_BVNULL;
  	sync_control *sr;
  	int rhint = 0;
  
  	if ( op->o_sync != SLAP_CONTROL_NONE ) {
  		rs->sr_text = "Sync control specified multiple times";
  		return LDAP_PROTOCOL_ERROR;
  	}
  
  	if ( op->o_pagedresults != SLAP_CONTROL_NONE ) {
  		rs->sr_text = "Sync control specified with pagedResults control";
  		return LDAP_PROTOCOL_ERROR;
  	}
  
  	if ( BER_BVISNULL( &ctrl->ldctl_value ) ) {
  		rs->sr_text = "Sync control value is absent";
  		return LDAP_PROTOCOL_ERROR;
  	}
  
  	if ( BER_BVISEMPTY( &ctrl->ldctl_value ) ) {
  		rs->sr_text = "Sync control value is empty";
  		return LDAP_PROTOCOL_ERROR;
  	}
  
  	/* Parse the control value
  	 *      syncRequestValue ::= SEQUENCE {
  	 *              mode   ENUMERATED {
  	 *                      -- 0 unused
  	 *                      refreshOnly		(1),
  	 *                      -- 2 reserved
  	 *                      refreshAndPersist	(3)
  	 *              },
  	 *              cookie  syncCookie OPTIONAL
  	 *      }
  	 */
  
  	ber_init2( ber, &ctrl->ldctl_value, 0 );
  
  	if ( (tag = ber_scanf( ber, "{i" /*}*/, &mode )) == LBER_ERROR ) {
  		rs->sr_text = "Sync control : mode decoding error";
  		return LDAP_PROTOCOL_ERROR;
  	}
  
  	switch( mode ) {
  	case LDAP_SYNC_REFRESH_ONLY:
  		mode = SLAP_SYNC_REFRESH;
  		break;
  	case LDAP_SYNC_REFRESH_AND_PERSIST:
  		mode = SLAP_SYNC_REFRESH_AND_PERSIST;
  		break;
  	default:
  		rs->sr_text = "Sync control : unknown update mode";
  		return LDAP_PROTOCOL_ERROR;
  	}
  
  	tag = ber_peek_tag( ber, &len );
  
  	if ( tag == LDAP_TAG_SYNC_COOKIE ) {
  		if (( ber_scanf( ber, /*{*/ "m", &cookie )) == LBER_ERROR ) {
  			rs->sr_text = "Sync control : cookie decoding error";
  			return LDAP_PROTOCOL_ERROR;
  		}
  		tag = ber_peek_tag( ber, &len );
  	}
  	if ( tag == LDAP_TAG_RELOAD_HINT ) {
  		if (( ber_scanf( ber, /*{*/ "b", &rhint )) == LBER_ERROR ) {
  			rs->sr_text = "Sync control : rhint decoding error";
  			return LDAP_PROTOCOL_ERROR;
  		}
  	}
  	if (( ber_scanf( ber, /*{*/ "}")) == LBER_ERROR ) {
  			rs->sr_text = "Sync control : decoding error";
  			return LDAP_PROTOCOL_ERROR;
  	}
  	sr = op->o_tmpcalloc( 1, sizeof(struct sync_control), op->o_tmpmemctx );
  	sr->sr_rhint = rhint;
  	if (!BER_BVISNULL(&cookie)) {
  		ber_dupbv_x( &sr->sr_state.octet_str, &cookie, op->o_tmpmemctx );
  		/* If parse fails, pretend no cookie was sent */
  		if ( slap_parse_sync_cookie( &sr->sr_state, op->o_tmpmemctx ) ||
  			sr->sr_state.rid == -1 ) {
  			if ( sr->sr_state.ctxcsn ) {
  				ber_bvarray_free_x( sr->sr_state.ctxcsn, op->o_tmpmemctx );
  				sr->sr_state.ctxcsn = NULL;
  			}
  			sr->sr_state.numcsns = 0;
  		}
  	}
  
  	op->o_controls[slap_cids.sc_LDAPsync] = sr;
  
  	op->o_sync = ctrl->ldctl_iscritical
  		? SLAP_CONTROL_CRITICAL
  		: SLAP_CONTROL_NONCRITICAL;
  
  	op->o_sync_mode |= mode;	/* o_sync_mode shares o_sync */
  
  	return LDAP_SUCCESS;
  }
  
  /* This overlay is set up for dynamic loading via moduleload. For static
   * configuration, you'll need to arrange for the slap_overinst to be
   * initialized and registered by some other function inside slapd.
   */
  
  static slap_overinst 		syncprov;
  
  int
  syncprov_initialize()
  {
  	int rc;
  
  	rc = register_supported_control( LDAP_CONTROL_SYNC,
  		SLAP_CTRL_SEARCH, NULL,
  		syncprov_parseCtrl, &slap_cids.sc_LDAPsync );
  	if ( rc != LDAP_SUCCESS ) {
  		Debug( LDAP_DEBUG_ANY,
  			"syncprov_init: Failed to register control %d\n", rc );
  		return rc;
  	}
  
  	syncprov.on_bi.bi_type = "syncprov";
  	syncprov.on_bi.bi_flags = SLAPO_BFLAG_SINGLE;
  	syncprov.on_bi.bi_db_init = syncprov_db_init;
  	syncprov.on_bi.bi_db_destroy = syncprov_db_destroy;
  	syncprov.on_bi.bi_db_open = syncprov_db_open;
  	syncprov.on_bi.bi_db_close = syncprov_db_close;
  
  	syncprov.on_bi.bi_op_abandon = syncprov_op_abandon;
  	syncprov.on_bi.bi_op_cancel = syncprov_op_abandon;
  
  	syncprov.on_bi.bi_op_add = syncprov_op_mod;
  	syncprov.on_bi.bi_op_compare = syncprov_op_compare;
  	syncprov.on_bi.bi_op_delete = syncprov_op_mod;
  	syncprov.on_bi.bi_op_modify = syncprov_op_mod;
  	syncprov.on_bi.bi_op_modrdn = syncprov_op_mod;
  	syncprov.on_bi.bi_op_search = syncprov_op_search;
  	syncprov.on_bi.bi_extended = syncprov_op_extended;
  	syncprov.on_bi.bi_operational = syncprov_operational;
  
  	syncprov.on_bi.bi_cf_ocs = spocs;
  
  	generic_filter.f_desc = slap_schema.si_ad_objectClass;
  
  	rc = config_register_schema( spcfg, spocs );
  	if ( rc ) return rc;
  
  	return overlay_register( &syncprov );
  }
  
  #if SLAPD_OVER_SYNCPROV == SLAPD_MOD_DYNAMIC
  int
  init_module( int argc, char *argv[] )
  {
  	return syncprov_initialize();
  }
  #endif /* SLAPD_OVER_SYNCPROV == SLAPD_MOD_DYNAMIC */
  
  #endif /* defined(SLAPD_OVER_SYNCPROV) */
  