]> git.sur5r.net Git - openldap/blobdiff - servers/slapd/backover.c
Partial revert of f30269f5d2e4bb5ee7486fe6542078d1b59dba6d
[openldap] / servers / slapd / backover.c
index 1a7f4bb34b5f9eb95929cfc22c2ebe653d078637..320b3385c01ef5402a63e90b6486c27dba8021cb 100644 (file)
@@ -2,7 +2,7 @@
 /* $OpenLDAP$ */
 /* This work is part of OpenLDAP Software <http://www.openldap.org/>.
  *
- * Copyright 2003-2005 The OpenLDAP Foundation.
+ * Copyright 2003-2012 The OpenLDAP Foundation.
  * All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
 
 static slap_overinst *overlays;
 
-enum db_which {
-       db_open = 0,
-       db_close,
-       db_destroy,
-       db_last
-};
-
-static int
-over_db_func(
-       BackendDB *be,
-       enum db_which which
-)
-{
-       slap_overinfo *oi = be->bd_info->bi_private;
-       slap_overinst *on = oi->oi_list;
-       BackendInfo *bi_orig = be->bd_info;
-       BI_db_open **func;
-       int rc = 0;
-
-       func = &oi->oi_orig->bi_db_open;
-       if ( func[which] ) {
-               be->bd_info = oi->oi_orig;
-               rc = func[which]( be );
-       }
-
-       for (; on && rc == 0; on=on->on_next) {
-               be->bd_info = &on->on_bi;
-               func = &on->on_bi.bi_db_open;
-               if (func[which]) {
-                       rc = func[which]( be );
-               }
-       }
-       be->bd_info = bi_orig;
-       return rc;
-}
-
 static int
 over_db_config(
        BackendDB *be,
@@ -137,6 +101,11 @@ over_db_config(
        ca.fname = fname;
        ca.lineno = lineno;
        ca.be = be;
+       snprintf( ca.log, sizeof( ca.log ), "%s: line %d",
+                       ca.fname, ca.lineno );
+       ca.op = SLAP_CONFIG_ADD;
+       ca.valx = -1;
+
        for (; on; on=on->on_next) {
                rc = SLAP_CONF_UNKNOWN;
                if (on->on_bi.bi_cf_ocs) {
@@ -144,6 +113,7 @@ over_db_config(
                        ca.bi = &on->on_bi;
                        ct = config_find_keyword( on->on_bi.bi_cf_ocs->co_table, &ca );
                        if ( ct ) {
+                               ca.table = on->on_bi.bi_cf_ocs->co_type;
                                rc = config_add_vals( ct, &ca );
                                if ( rc != SLAP_CONF_UNKNOWN )
                                        break;
@@ -164,15 +134,35 @@ over_db_config(
 
 static int
 over_db_open(
-       BackendDB *be
+       BackendDB *be,
+       ConfigReply *cr
 )
 {
-       return over_db_func( be, db_open );
+       slap_overinfo *oi = be->bd_info->bi_private;
+       slap_overinst *on = oi->oi_list;
+       BackendDB db = *be;
+       int rc = 0;
+
+       db.be_flags |= SLAP_DBFLAG_OVERLAY;
+       db.bd_info = oi->oi_orig;
+       if ( db.bd_info->bi_db_open ) {
+               rc = db.bd_info->bi_db_open( &db, cr );
+       }
+
+       for (; on && rc == 0; on=on->on_next) {
+               db.bd_info = &on->on_bi;
+               if ( db.bd_info->bi_db_open ) {
+                       rc = db.bd_info->bi_db_open( &db, cr );
+               }
+       }
+
+       return rc;
 }
 
 static int
 over_db_close(
-       BackendDB *be
+       BackendDB *be,
+       ConfigReply *cr
 )
 {
        slap_overinfo *oi = be->bd_info->bi_private;
@@ -183,13 +173,13 @@ over_db_close(
        for (; on && rc == 0; on=on->on_next) {
                be->bd_info = &on->on_bi;
                if ( be->bd_info->bi_db_close ) {
-                       rc = be->bd_info->bi_db_close( be );
+                       rc = be->bd_info->bi_db_close( be, cr );
                }
        }
 
        if ( oi->oi_orig->bi_db_close ) {
                be->bd_info = oi->oi_orig;
-               rc = be->bd_info->bi_db_close( be );
+               rc = be->bd_info->bi_db_close( be, cr );
        }
 
        be->bd_info = bi_orig;
@@ -198,19 +188,35 @@ over_db_close(
 
 static int
 over_db_destroy(
-       BackendDB *be
+       BackendDB *be,
+       ConfigReply *cr
 )
 {
        slap_overinfo *oi = be->bd_info->bi_private;
        slap_overinst *on = oi->oi_list, *next;
-       int rc;
+       BackendInfo *bi_orig = be->bd_info;
+       int rc = 0;
+
+       be->bd_info = oi->oi_orig;
+       if ( be->bd_info->bi_db_destroy ) {
+               rc = be->bd_info->bi_db_destroy( be, cr );
+       }
 
-       rc = over_db_func( be, db_destroy );
+       for (; on && rc == 0; on=on->on_next) {
+               be->bd_info = &on->on_bi;
+               if ( be->bd_info->bi_db_destroy ) {
+                       rc = be->bd_info->bi_db_destroy( be, cr );
+               }
+       }
 
-       for (next = on->on_next; on; on=next) {
-               next = on->on_next;
-               free( on );
+       on = oi->oi_list;
+       if ( on ) {
+               for (next = on->on_next; on; on=next) {
+                       next = on->on_next;
+                       free( on );
+               }
        }
+       be->bd_info = bi_orig;
        free( oi );
        return rc;
 }
@@ -232,11 +238,15 @@ over_back_response ( Operation *op, SlapReply *rs )
                        if ( rc != SLAP_CB_CONTINUE ) break;
                }
        }
+       /* Bypass the remaining on_response layers, but allow
+        * normal execution to continue.
+        */
+       if ( rc == SLAP_CB_BYPASS )
+               rc = SLAP_CB_CONTINUE;
        op->o_bd = be;
        return rc;
 }
 
-#ifdef SLAP_OVERLAY_ACCESS
 static int
 over_access_allowed(
        Operation               *op,
@@ -249,7 +259,7 @@ over_access_allowed(
 {
        slap_overinfo *oi;
        slap_overinst *on;
-       BackendInfo *bi = op->o_bd->bd_info;
+       BackendInfo *bi;
        BackendDB *be = op->o_bd, db;
        int rc = SLAP_CB_CONTINUE;
 
@@ -257,7 +267,13 @@ over_access_allowed(
         * when global overlays are used... */
        assert( op->o_bd != NULL );
 
-       oi = op->o_bd->bd_info->bi_private;
+       bi = op->o_bd->bd_info;
+       /* Were we invoked on the frontend? */
+       if ( !bi->bi_access_allowed ) {
+               oi = frontendDB->bd_info->bi_private;
+       } else {
+               oi = op->o_bd->bd_info->bi_private;
+       }
        on = oi->oi_list;
 
        for ( ; on; on = on->on_next ) {
@@ -306,6 +322,147 @@ over_access_allowed(
        return rc;
 }
 
+int
+overlay_entry_get_ov(
+       Operation               *op,
+       struct berval   *dn,
+       ObjectClass             *oc,
+       AttributeDescription    *ad,
+       int     rw,
+       Entry   **e,
+       slap_overinst *on )
+{
+       slap_overinfo *oi = on->on_info;
+       BackendDB *be = op->o_bd, db;
+       BackendInfo *bi = op->o_bd->bd_info;
+       int rc = SLAP_CB_CONTINUE;
+
+       for ( ; on; on = on->on_next ) {
+               if ( on->on_bi.bi_entry_get_rw ) {
+                       /* NOTE: do not copy the structure until required */
+                       if ( !SLAP_ISOVERLAY( op->o_bd ) ) {
+                               db = *op->o_bd;
+                               db.be_flags |= SLAP_DBFLAG_OVERLAY;
+                               op->o_bd = &db;
+                       }
+
+                       op->o_bd->bd_info = (BackendInfo *)on;
+                       rc = on->on_bi.bi_entry_get_rw( op, dn,
+                               oc, ad, rw, e );
+                       if ( rc != SLAP_CB_CONTINUE ) break;
+               }
+       }
+
+       if ( rc == SLAP_CB_CONTINUE ) {
+               /* if the database structure was changed, o_bd points to a
+                * copy of the structure; put the original bd_info in place */
+               if ( SLAP_ISOVERLAY( op->o_bd ) ) {
+                       op->o_bd->bd_info = oi->oi_orig;
+               }
+
+               if ( oi->oi_orig->bi_entry_get_rw ) {
+                       rc = oi->oi_orig->bi_entry_get_rw( op, dn,
+                               oc, ad, rw, e );
+               }
+       }
+       /* should not fall thru this far without anything happening... */
+       if ( rc == SLAP_CB_CONTINUE ) {
+               rc = LDAP_UNWILLING_TO_PERFORM;
+       }
+
+       op->o_bd = be;
+       op->o_bd->bd_info = bi;
+
+       return rc;
+}
+
+static int
+over_entry_get_rw(
+       Operation               *op,
+       struct berval   *dn,
+       ObjectClass             *oc,
+       AttributeDescription    *ad,
+       int     rw,
+       Entry   **e )
+{
+       slap_overinfo *oi;
+       slap_overinst *on;
+
+       assert( op->o_bd != NULL );
+
+       oi = op->o_bd->bd_info->bi_private;
+       on = oi->oi_list;
+
+       return overlay_entry_get_ov( op, dn, oc, ad, rw, e, on );
+}
+
+int
+overlay_entry_release_ov(
+       Operation       *op,
+       Entry   *e,
+       int rw,
+       slap_overinst *on )
+{
+       slap_overinfo *oi = on->on_info;
+       BackendDB *be = op->o_bd, db;
+       BackendInfo *bi = op->o_bd->bd_info;
+       int rc = SLAP_CB_CONTINUE;
+
+       for ( ; on; on = on->on_next ) {
+               if ( on->on_bi.bi_entry_release_rw ) {
+                       /* NOTE: do not copy the structure until required */
+                       if ( !SLAP_ISOVERLAY( op->o_bd ) ) {
+                               db = *op->o_bd;
+                               db.be_flags |= SLAP_DBFLAG_OVERLAY;
+                               op->o_bd = &db;
+                       }
+
+                       op->o_bd->bd_info = (BackendInfo *)on;
+                       rc = on->on_bi.bi_entry_release_rw( op, e, rw );
+                       if ( rc != SLAP_CB_CONTINUE ) break;
+               }
+       }
+
+       if ( rc == SLAP_CB_CONTINUE ) {
+               /* if the database structure was changed, o_bd points to a
+                * copy of the structure; put the original bd_info in place */
+               if ( SLAP_ISOVERLAY( op->o_bd ) ) {
+                       op->o_bd->bd_info = oi->oi_orig;
+               }
+
+               if ( oi->oi_orig->bi_entry_release_rw ) {
+                       rc = oi->oi_orig->bi_entry_release_rw( op, e, rw );
+               }
+       }
+       /* should not fall thru this far without anything happening... */
+       if ( rc == SLAP_CB_CONTINUE ) {
+               entry_free( e );
+               rc = 0;
+       }
+
+       op->o_bd = be;
+       op->o_bd->bd_info = bi;
+
+       return rc;
+}
+
+static int
+over_entry_release_rw(
+       Operation       *op,
+       Entry   *e,
+       int rw )
+{
+       slap_overinfo *oi;
+       slap_overinst *on;
+
+       assert( op->o_bd != NULL );
+
+       oi = op->o_bd->bd_info->bi_private;
+       on = oi->oi_list;
+
+       return overlay_entry_release_ov( op, e, rw, on );
+}
+
 static int
 over_acl_group(
        Operation               *op,
@@ -317,15 +474,16 @@ over_acl_group(
 {
        slap_overinfo *oi;
        slap_overinst *on;
-       BackendInfo *bi = op->o_bd->bd_info;
+       BackendInfo *bi;
        BackendDB *be = op->o_bd, db;
        int rc = SLAP_CB_CONTINUE;
 
        /* FIXME: used to happen for instance during abandon
         * when global overlays are used... */
-       assert( op->o_bd != NULL );
+       assert( be != NULL );
 
-       oi = op->o_bd->bd_info->bi_private;
+       bi = be->bd_info;
+       oi = bi->bi_private;
        on = oi->oi_list;
 
        for ( ; on; on = on->on_next ) {
@@ -385,15 +543,16 @@ over_acl_attribute(
 {
        slap_overinfo *oi;
        slap_overinst *on;
-       BackendInfo *bi = op->o_bd->bd_info;
+       BackendInfo *bi;
        BackendDB *be = op->o_bd, db;
        int rc = SLAP_CB_CONTINUE;
 
        /* FIXME: used to happen for instance during abandon
         * when global overlays are used... */
-       assert( op->o_bd != NULL );
+       assert( be != NULL );
 
-       oi = op->o_bd->bd_info->bi_private;
+       bi = be->bd_info;
+       oi = bi->bi_private;
        on = oi->oi_list;
 
        for ( ; on; on = on->on_next ) {
@@ -441,7 +600,27 @@ over_acl_attribute(
 
        return rc;
 }
-#endif /* SLAP_OVERLAY_ACCESS */
+
+int
+overlay_callback_after_backover( Operation *op, slap_callback *sc, int append )
+{
+       slap_callback **scp;
+
+       for ( scp = &op->o_callback; *scp != NULL; scp = &(*scp)->sc_next ) {
+               if ( (*scp)->sc_response == over_back_response ) {
+                       sc->sc_next = (*scp)->sc_next;
+                       (*scp)->sc_next = sc;
+                       return 0;
+               }
+       }
+
+       if ( append ) {
+               *scp = sc;
+               return 0;
+       }
+
+       return 1;
+}
 
 /*
  * default return code in case of missing backend function
@@ -483,6 +662,8 @@ int overlay_op_walk(
                        if ( rc != SLAP_CB_CONTINUE ) break;
                }
        }
+       if ( rc == SLAP_CB_BYPASS )
+               rc = SLAP_CB_CONTINUE;
 
        func = &oi->oi_orig->bi_op_bind;
        if ( func[which] && rc == SLAP_CB_CONTINUE ) {
@@ -520,7 +701,7 @@ over_op_func(
        slap_overinfo *oi;
        slap_overinst *on;
        BackendDB *be = op->o_bd, db;
-       slap_callback cb = {NULL, over_back_response, NULL, NULL};
+       slap_callback cb = {NULL, over_back_response, NULL, NULL}, **sc;
        int rc = SLAP_CB_CONTINUE;
 
        /* FIXME: used to happen for instance during abandon
@@ -540,9 +721,14 @@ over_op_func(
        op->o_callback = &cb;
 
        rc = overlay_op_walk( op, rs, which, oi, on );
+       for ( sc = &op->o_callback; *sc; sc = &(*sc)->sc_next ) {
+               if ( *sc == &cb ) {
+                       *sc = cb.sc_next;
+                       break;
+               }
+       }
 
        op->o_bd = be;
-       op->o_callback = cb.sc_next;
        return rc;
 }
 
@@ -707,6 +893,69 @@ overlay_register(
        slap_overinst *on
 )
 {
+       slap_overinst   *tmp;
+
+       /* FIXME: check for duplicates? */
+       for ( tmp = overlays; tmp != NULL; tmp = tmp->on_next ) {
+               if ( strcmp( on->on_bi.bi_type, tmp->on_bi.bi_type ) == 0 ) {
+                       Debug( LDAP_DEBUG_ANY,
+                               "overlay_register(\"%s\"): "
+                               "name already in use.\n",
+                               on->on_bi.bi_type, 0, 0 );
+                       return -1;
+               }
+
+               if ( on->on_bi.bi_obsolete_names != NULL ) {
+                       int     i;
+
+                       for ( i = 0; on->on_bi.bi_obsolete_names[ i ] != NULL; i++ ) {
+                               if ( strcmp( on->on_bi.bi_obsolete_names[ i ], tmp->on_bi.bi_type ) == 0 ) {
+                                       Debug( LDAP_DEBUG_ANY,
+                                               "overlay_register(\"%s\"): "
+                                               "obsolete name \"%s\" already in use "
+                                               "by overlay \"%s\".\n",
+                                               on->on_bi.bi_type,
+                                               on->on_bi.bi_obsolete_names[ i ],
+                                               tmp->on_bi.bi_type );
+                                       return -1;
+                               }
+                       }
+               }
+
+               if ( tmp->on_bi.bi_obsolete_names != NULL ) {
+                       int     i;
+
+                       for ( i = 0; tmp->on_bi.bi_obsolete_names[ i ] != NULL; i++ ) {
+                               int     j;
+
+                               if ( strcmp( on->on_bi.bi_type, tmp->on_bi.bi_obsolete_names[ i ] ) == 0 ) {
+                                       Debug( LDAP_DEBUG_ANY,
+                                               "overlay_register(\"%s\"): "
+                                               "name already in use "
+                                               "as obsolete by overlay \"%s\".\n",
+                                               on->on_bi.bi_type,
+                                               tmp->on_bi.bi_obsolete_names[ i ], 0 );
+                                       return -1;
+                               }
+
+                               if ( on->on_bi.bi_obsolete_names != NULL ) {
+                                       for ( j = 0; on->on_bi.bi_obsolete_names[ j ] != NULL; j++ ) {
+                                               if ( strcmp( on->on_bi.bi_obsolete_names[ j ], tmp->on_bi.bi_obsolete_names[ i ] ) == 0 ) {
+                                                       Debug( LDAP_DEBUG_ANY,
+                                                               "overlay_register(\"%s\"): "
+                                                               "obsolete name \"%s\" already in use "
+                                                               "as obsolete by overlay \"%s\".\n",
+                                                               on->on_bi.bi_type,
+                                                               on->on_bi.bi_obsolete_names[ j ],
+                                                               tmp->on_bi.bi_type );
+                                                       return -1;
+                                               }
+                                       }
+                               }
+                       }
+               }
+       }
+
        on->on_next = overlays;
        overlays = on;
        return 0;
@@ -714,8 +963,8 @@ overlay_register(
 
 /*
  * iterator on registered overlays; overlay_next( NULL ) returns the first
- * overlay; subsequent calls with the previously returned value allow to 
- * iterate over the entire list; returns NULL when no more overlays are 
+ * overlay; subsequent calls with the previously returned value allow to 
+ * iterate over the entire list; returns NULL when no more overlays are 
  * registered.
  */
 
@@ -745,10 +994,26 @@ overlay_find( const char *over_type )
 
        for ( ; on; on = on->on_next ) {
                if ( strcmp( on->on_bi.bi_type, over_type ) == 0 ) {
-                       break;
+                       goto foundit;
+               }
+
+               if ( on->on_bi.bi_obsolete_names != NULL ) {
+                       int     i;
+
+                       for ( i = 0; on->on_bi.bi_obsolete_names[ i ] != NULL; i++ ) {
+                               if ( strcmp( on->on_bi.bi_obsolete_names[ i ], over_type ) == 0 ) {
+                                       Debug( LDAP_DEBUG_ANY,
+                                               "overlay_find(\"%s\"): "
+                                               "obsolete name for \"%s\".\n",
+                                               on->on_bi.bi_obsolete_names[ i ],
+                                               on->on_bi.bi_type, 0 );
+                                       goto foundit;
+                               }
+                       }
                }
        }
 
+foundit:;
        return on;
 }
 
@@ -802,29 +1067,67 @@ overlay_register_control( BackendDB *be, const char *oid )
                return -1;
        }
 
-       if ( SLAP_DBFLAGS( be ) & SLAP_DBFLAG_GLOBAL_OVERLAY ) {
+       if ( SLAP_ISGLOBALOVERLAY( be ) ) {
                BackendDB *bd;
                
                /* add to all backends... */
                LDAP_STAILQ_FOREACH( bd, &backendDB, be_next ) {
-                       if ( be == bd ) {
+                       if ( bd == be->bd_self ) {
                                gotit = 1;
                        }
 
-                       bd->be_ctrls[ cid ] = 1;
+                       /* overlays can be instanciated multiple times, use
+                        * be_ctrls[ cid ] as an instance counter, so that the
+                        * overlay's controls are only really disabled after the
+                        * last instance called overlay_register_control() */
+                       bd->be_ctrls[ cid ]++;
                        bd->be_ctrls[ SLAP_MAX_CIDS ] = 1;
                }
 
        }
        
        if ( !gotit ) {
-               be->be_ctrls[ cid ] = 1;
-               be->be_ctrls[ SLAP_MAX_CIDS ] = 1;
+               /* overlays can be instanciated multiple times, use
+                * be_ctrls[ cid ] as an instance counter, so that the
+                * overlay's controls are only really unregistered after the
+                * last instance called overlay_register_control() */
+               be->bd_self->be_ctrls[ cid ]++;
+               be->bd_self->be_ctrls[ SLAP_MAX_CIDS ] = 1;
        }
 
        return 0;
 }
 
+#ifdef SLAP_CONFIG_DELETE
+void
+overlay_unregister_control( BackendDB *be, const char *oid )
+{
+       int             gotit = 0;
+       int             cid;
+
+       if ( slap_find_control_id( oid, &cid ) == LDAP_CONTROL_NOT_FOUND ) {
+               return;
+       }
+
+       if ( SLAP_ISGLOBALOVERLAY( be ) ) {
+               BackendDB *bd;
+
+               /* remove from all backends... */
+               LDAP_STAILQ_FOREACH( bd, &backendDB, be_next ) {
+                       if ( bd == be->bd_self ) {
+                               gotit = 1;
+                       }
+
+                       bd->be_ctrls[ cid ]--;
+               }
+       }
+
+       if ( !gotit ) {
+               be->bd_self->be_ctrls[ cid ]--;
+       }
+}
+#endif /* SLAP_CONFIG_DELETE */
+
 void
 overlay_destroy_one( BackendDB *be, slap_overinst *on )
 {
@@ -837,7 +1140,7 @@ overlay_destroy_one( BackendDB *be, slap_overinst *on )
                        if ( on->on_bi.bi_db_destroy ) {
                                BackendInfo *bi_orig = be->bd_info;
                                be->bd_info = (BackendInfo *)on;
-                               on->on_bi.bi_db_destroy( be );
+                               on->on_bi.bi_db_destroy( be, NULL );
                                be->bd_info = bi_orig;
                        }
                        free( on );
@@ -846,14 +1149,141 @@ overlay_destroy_one( BackendDB *be, slap_overinst *on )
        }
 }
 
+#ifdef SLAP_CONFIG_DELETE
+typedef struct ov_remove_ctx {
+       BackendDB *be;
+       slap_overinst *on;
+} ov_remove_ctx;
+
+int
+overlay_remove_cb( Operation *op, SlapReply *rs )
+{
+       ov_remove_ctx *rm_ctx = (ov_remove_ctx*) op->o_callback->sc_private;
+       BackendInfo *bi_orig = rm_ctx->be->bd_info;
+
+       rm_ctx->be->bd_info = (BackendInfo*) rm_ctx->on;
+
+       if ( rm_ctx->on->on_bi.bi_db_close ) {
+               rm_ctx->on->on_bi.bi_db_close( rm_ctx->be, NULL );
+       }
+       if ( rm_ctx->on->on_bi.bi_db_destroy ) {
+               rm_ctx->on->on_bi.bi_db_destroy( rm_ctx->be, NULL );
+       }
+
+       /* clean up after removing last overlay */
+       if ( ! rm_ctx->on->on_info->oi_list ) {
+               /* reset db flags and bd_info to orig */
+               SLAP_DBFLAGS( rm_ctx->be ) &= ~SLAP_DBFLAG_GLOBAL_OVERLAY;
+               rm_ctx->be->bd_info = rm_ctx->on->on_info->oi_orig;
+               ch_free(rm_ctx->on->on_info);
+       } else {
+               rm_ctx->be->bd_info = bi_orig;
+       }
+       free( rm_ctx->on );
+       op->o_tmpfree(rm_ctx, op->o_tmpmemctx);
+       return SLAP_CB_CONTINUE;
+}
+
+void
+overlay_remove( BackendDB *be, slap_overinst *on, Operation *op )
+{
+       slap_overinfo *oi = on->on_info;
+       slap_overinst **oidx;
+       ov_remove_ctx *rm_ctx;
+       slap_callback *rm_cb, *cb;
+
+       /* remove overlay from oi_list */
+       for ( oidx = &oi->oi_list; *oidx; oidx = &(*oidx)->on_next ) {
+               if ( *oidx == on ) {
+                       *oidx = on->on_next;
+                       break;
+               }
+       }
+
+       /* The db_close and db_destroy handlers to cleanup a release
+        * the overlay's resources are called from the cleanup callback
+        */
+       rm_ctx = op->o_tmpalloc( sizeof( ov_remove_ctx ), op->o_tmpmemctx );
+       rm_ctx->be = be;
+       rm_ctx->on = on;
+
+       rm_cb = op->o_tmpalloc( sizeof( slap_callback ), op->o_tmpmemctx );
+       rm_cb->sc_next = NULL;
+       rm_cb->sc_cleanup = overlay_remove_cb;
+       rm_cb->sc_response = NULL;
+       rm_cb->sc_private = (void*) rm_ctx;
+
+       /* Append callback to the end of the list */
+       for ( cb = op->o_callback; cb->sc_next; cb = cb->sc_next );
+       cb->sc_next = rm_cb;
+}
+#endif /* SLAP_CONFIG_DELETE */
+
+void
+overlay_insert( BackendDB *be, slap_overinst *on2, slap_overinst ***prev,
+       int idx )
+{
+       slap_overinfo *oi = (slap_overinfo *)be->bd_info;
+
+       if ( idx == -1 ) {
+               on2->on_next = oi->oi_list;
+               oi->oi_list = on2;
+       } else {
+               int i, novs;
+               slap_overinst *on, **prev;
+
+               /* Since the list is in reverse order and is singly linked,
+                * we have to count the overlays and then insert backwards.
+                * Adding on overlay at a specific point should be a pretty
+                * infrequent occurrence.
+                */
+               novs = 0;
+               for ( on = oi->oi_list; on; on=on->on_next )
+                       novs++;
+
+               if (idx > novs)
+                       idx = 0;
+               else
+                       idx = novs - idx;
+
+               /* advance to insertion point */
+               prev = &oi->oi_list;
+               for ( i=0; i<idx; i++ ) {
+                       on = *prev;
+                       prev = &on->on_next;
+               }
+               /* insert */
+               on2->on_next = *prev;
+               *prev = on2;
+       }
+}
+
+void
+overlay_move( BackendDB *be, slap_overinst *on, int idx )
+{
+       slap_overinfo *oi = (slap_overinfo *)be->bd_info;
+       slap_overinst **onp;
+
+       for (onp = &oi->oi_list; *onp; onp= &(*onp)->on_next) {
+               if ( *onp == on ) {
+                       *onp = on->on_next;
+                       break;
+               }
+       }
+       overlay_insert( be, on, &onp, idx );
+}
+
 /* add an overlay to a particular backend. */
 int
-overlay_config( BackendDB *be, const char *ov )
+overlay_config( BackendDB *be, const char *ov, int idx, BackendInfo **res, ConfigReply *cr )
 {
-       slap_overinst *on = NULL, *on2 = NULL;
+       slap_overinst *on = NULL, *on2 = NULL, **prev;
        slap_overinfo *oi = NULL;
        BackendInfo *bi = NULL;
 
+       if ( res )
+               *res = NULL;
+
        on = overlay_find( ov );
        if ( !on ) {
                Debug( LDAP_DEBUG_ANY, "overlay \"%s\" not found\n", ov, 0, 0 );
@@ -864,15 +1294,33 @@ overlay_config( BackendDB *be, const char *ov )
         * overlay info structure
         */
        if ( !overlay_is_over( be ) ) {
+               int     isglobal = 0;
+
+               /* NOTE: the first time a global overlay is configured,
+                * frontendDB gets this flag; it is used later by overlays
+                * to determine if they're stacked on top of the frontendDB */
+               if ( be->bd_info == frontendDB->bd_info || SLAP_ISGLOBALOVERLAY( be ) ) {
+                       isglobal = 1;
+                       if ( on->on_bi.bi_flags & SLAPO_BFLAG_DBONLY ) {
+                               Debug( LDAP_DEBUG_ANY, "overlay_config(): "
+                                       "overlay \"%s\" cannot be global.\n",
+                                       ov, 0, 0 );
+                               return 1;
+                       }
+
+               } else if ( on->on_bi.bi_flags & SLAPO_BFLAG_GLOBONLY ) {
+                       Debug( LDAP_DEBUG_ANY, "overlay_config(): "
+                               "overlay \"%s\" can only be global.\n",
+                               ov, 0, 0 );
+                       return 1;
+               }
+
                oi = ch_malloc( sizeof( slap_overinfo ) );
                oi->oi_orig = be->bd_info;
                oi->oi_bi = *be->bd_info;
                oi->oi_origdb = be;
 
-               /* NOTE: the first time a global overlay is configured,
-                * frontendDB gets this flag; it is used later by overlays
-                * to determine if they're stacked on top of the frontendDB */
-               if ( oi->oi_orig == frontendDB->bd_info ) {
+               if ( isglobal ) {
                        SLAP_DBFLAGS( be ) |= SLAP_DBFLAG_GLOBAL_OVERLAY;
                }
 
@@ -912,12 +1360,12 @@ overlay_config( BackendDB *be, const char *ov )
                bi->bi_chk_referrals = over_aux_chk_referrals;
                bi->bi_chk_controls = over_aux_chk_controls;
 
-#ifdef SLAP_OVERLAY_ACCESS
                /* these have specific arglists */
+               bi->bi_entry_get_rw = over_entry_get_rw;
+               bi->bi_entry_release_rw = over_entry_release_rw;
                bi->bi_access_allowed = over_access_allowed;
                bi->bi_acl_group = over_acl_group;
                bi->bi_acl_attribute = over_acl_attribute;
-#endif /* SLAP_OVERLAY_ACCESS */
                
                bi->bi_connection_init = over_connection_init;
                bi->bi_connection_destroy = over_connection_destroy;
@@ -926,32 +1374,55 @@ overlay_config( BackendDB *be, const char *ov )
 
        } else {
                if ( overlay_is_inst( be, ov ) ) {
-                       Debug( LDAP_DEBUG_ANY, "overlay_config(): "
-                                       "warning, overlay \"%s\" "
-                                       "already in list\n", ov, 0, 0 );
+                       if ( SLAPO_SINGLE( be ) ) {
+                               Debug( LDAP_DEBUG_ANY, "overlay_config(): "
+                                       "overlay \"%s\" already in list\n",
+                                       ov, 0, 0 );
+                               return 1;
+                       }
                }
 
                oi = be->bd_info->bi_private;
        }
 
-       /* Insert new overlay on head of list. Overlays are executed
-        * in reverse of config order...
+       /* Insert new overlay into list. By default overlays are
+        * added to head of list and executed in LIFO order.
         */
        on2 = ch_calloc( 1, sizeof(slap_overinst) );
        *on2 = *on;
        on2->on_info = oi;
-       on2->on_next = oi->oi_list;
-       oi->oi_list = on2;
+
+       prev = &oi->oi_list;
+       /* Do we need to find the insertion point? */
+       if ( idx >= 0 ) {
+               int i;
+
+               /* count current overlays */
+               for ( i=0, on=oi->oi_list; on; on=on->on_next, i++ );
+
+               /* are we just appending a new one? */
+               if ( idx >= i )
+                       idx = -1;
+       }
+       overlay_insert( be, on2, &prev, idx );
 
        /* Any initialization needed? */
-       if ( on->on_bi.bi_db_init ) {
+       if ( on2->on_bi.bi_db_init ) {
                int rc;
                be->bd_info = (BackendInfo *)on2;
-               rc = on2->on_bi.bi_db_init( be );
+               rc = on2->on_bi.bi_db_init( be, cr);
                be->bd_info = (BackendInfo *)oi;
-               if ( rc ) return rc;
+               if ( rc ) {
+                       *prev = on2->on_next;
+                       ch_free( on2 );
+                       on2 = NULL;
+                       return rc;
+               }
        }
 
+       if ( res )
+               *res = &on2->on_bi;
+
        return 0;
 }