Adding upstream version 2.5.13+dfsg.upstream/2.5.13+dfsgupstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 4368 insertions, 0 deletions

diff --git a/servers/slapd/overlays/syncprov.c b/servers/slapd/overlays/syncprov.c
new file mode 100644
index 0000000..6d749a5
--- /dev/null
+++ b/servers/slapd/overlays/syncprov.c
@@ -0,0 +1,4368 @@
+/* $OpenLDAP$ */
+/* 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_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;
+
+	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 ) {
+		struct berval pdn;
+		if ( op->orr_nnewSup ) pdn = *op->orr_nnewSup;
+		else dnParent( fc.fdn, &pdn );
+		build_new_dn( &newdn, &pdn, &op->orr_nnewrdn, op->o_tmpmemctx );
+		fc.fdn = &newdn;
+		freefdn = 1;
+	}
+	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;
+				}
+			}
+		}
+
+		if ( 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;
+
+	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_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 ) {
+			switch(op->o_tag) {
+			case LDAP_REQ_ADD:
+			case LDAP_REQ_MODIFY:
+			case LDAP_REQ_MODRDN:
+			case LDAP_REQ_EXTENDED:
+				syncprov_matchops( op, opc, 0 );
+				break;
+			case LDAP_REQ_DELETE:
+				/* for each match in opc->smatches:
+				 *   send DELETE msg
+				 */
+				for ( sm = opc->smatches; sm; sm=sm->sm_next ) {
+					if ( sm->sm_op->s_op->o_abandon )
+						continue;
+					syncprov_qresp( opc, sm->sm_op, LDAP_SYNC_DELETE );
+				}
+				if ( opc->ssres.s_info )
+					free_resinfo( &opc->ssres );
+				break;
+			}
+		}
+
+		/* 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_pausecheck( &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;
+
+	/* Prevent anyone else from trying to send a result for this op */
+	op->o_abandon = 1;
+}
+
+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;
+		}
+		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 LDAP_SUCCESS;
+		}
+	}
+
+	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 );
+
+		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 ) {
+aband:
+				ch_free( sop->s_base.bv_val );
+				ch_free( sop );
+				return SLAPD_ABANDON;
+			}
+			if ( !ldap_pvt_thread_pool_pausecheck( &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 );
+			goto aband;
+		}
+		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\n",
+				op->o_log_prefix );
+
+			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->s_base.bv_val );
+					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;
+			}
+		} else if ( ad_minCSN != NULL && si->si_nopres && si->si_usehint ) {
+			/* We are instructed to trust minCSN if it exists. */
+			Entry *e;
+			Attribute *a = NULL;
+			int rc;
+
+			/*
+			 * ITS#9580 FIXME: when we've figured out and split the
+			 * sessionlog/deltalog tracking, use the appropriate attribute
+			 */
+			rc = overlay_entry_get_ov( op, &op->o_bd->be_nsuffix[0], NULL,
+					ad_minCSN, 0, &e, on );
+			if ( rc == LDAP_SUCCESS && e != NULL ) {
+				a = attr_find( e->e_attrs, ad_minCSN );
+			}
+
+			if ( a != NULL ) {
+				int *minsids;
+
+				minsids = slap_parse_csn_sids( a->a_vals, a->a_numvals, op->o_tmpmemctx );
+				slap_sort_csn_sids( a->a_vals, minsids, a->a_numvals, op->o_tmpmemctx );
+
+				for ( i=0, j=0; i < a->a_numvals; i++ ) {
+					while ( j < numcsns && minsids[i] > sids[j] ) j++;
+					if ( j < numcsns && minsids[i] == sids[j] &&
+							ber_bvcmp( &a->a_vals[i], &srs->sr_state.ctxcsn[j] ) <= 0 ) {
+						/* minCSN for this serverID is contained, keep going */
+						continue;
+					}
+					/*
+					 * Log DB's minCSN claims we can only replay from a certain
+					 * CSN for this serverID, but consumer's cookie hasn't met that
+					 * threshold: they need to refresh
+					 */
+					Debug( LDAP_DEBUG_SYNC, "%s syncprov_op_search: "
+						"consumer not within recorded mincsn for DB's mincsn=%s\n",
+						op->o_log_prefix, a->a_vals[i].bv_val );
+					rs->sr_err = LDAP_SYNC_REFRESH_REQUIRED;
+					rs->sr_text = "sync cookie is stale";
+					slap_sl_free( minsids, op->o_tmpmemctx );
+					overlay_entry_release_ov( op, e, 0, on );
+					goto bailout;
+				}
+				slap_sl_free( minsids, op->o_tmpmemctx );
+			}
+			if ( e != NULL )
+				overlay_entry_release_ov( op, e, 0, on );
+		}
+
+		/*
+		 * 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;
+		if ( si->si_usehint ) {
+			/* Consider we might be a delta provider, but it's ok if not */
+			(void)syncprov_setup_accesslog();
+		}
+		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 );
+		if ( si->si_logbase.bv_val )
+			ch_free( si->si_logbase.bv_val );
+		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) */