git.sur5r.net Git - openldap/blob - servers/slapd/backover.c

   1 /* backover.c - backend overlay routines */
   2 /* $OpenLDAP$ */
   3 /* This work is part of OpenLDAP Software <http://www.openldap.org/>.
   4  *
   5  * Copyright 2003-2010 The OpenLDAP Foundation.
   6  * All rights reserved.
   7  *
   8  * Redistribution and use in source and binary forms, with or without
   9  * modification, are permitted only as authorized by the OpenLDAP
  10  * Public License.
  11  *
  12  * A copy of this license is available in the file LICENSE in the
  13  * top-level directory of the distribution or, alternatively, at
  14  * <http://www.OpenLDAP.org/license.html>.
  15  */
  16
  17 /* Functions to overlay other modules over a backend. */
  18
  19 #include "portable.h"
  20
  21 #include <stdio.h>
  22
  23 #include <ac/string.h>
  24 #include <ac/socket.h>
  25
  26 #define SLAPD_TOOLS
  27 #include "slap.h"
  28 #include "config.h"
  29
  30 static slap_overinst *overlays;
  31
  32 static int
  33 over_db_config(
  34         BackendDB *be,
  35         const char *fname,
  36         int lineno,
  37         int argc,
  38         char **argv
  39 )
  40 {
  41         slap_overinfo *oi = be->bd_info->bi_private;
  42         slap_overinst *on = oi->oi_list;
  43         BackendInfo *bi_orig = be->bd_info;
  44         struct ConfigOCs *be_cf_ocs = be->be_cf_ocs;
  45         ConfigArgs ca = {0};
  46         int rc = 0;
  47
  48         if ( oi->oi_orig->bi_db_config ) {
  49                 be->bd_info = oi->oi_orig;
  50                 be->be_cf_ocs = oi->oi_orig->bi_cf_ocs;
  51                 rc = oi->oi_orig->bi_db_config( be, fname, lineno,
  52                         argc, argv );
  53
  54                 if ( be->bd_info != oi->oi_orig ) {
  55                         slap_overinfo   *oi2;
  56                         slap_overinst   *on2, **onp;
  57                         BackendDB       be2 = *be;
  58                         int             i;
  59
  60                         /* a database added an overlay;
  61                          * work it around... */
  62                         assert( overlay_is_over( be ) );
  63
  64                         oi2 = ( slap_overinfo * )be->bd_info->bi_private;
  65                         on2 = oi2->oi_list;
  66
  67                         /* need to put a uniqueness check here as well;
  68                          * note that in principle there could be more than
  69                          * one overlay as a result of multiple calls to
  70                          * overlay_config() */
  71                         be2.bd_info = (BackendInfo *)oi;
  72
  73                         for ( i = 0, onp = &on2; *onp; i++, onp = &(*onp)->on_next ) {
  74                                 if ( overlay_is_inst( &be2, (*onp)->on_bi.bi_type ) ) {
  75                                         Debug( LDAP_DEBUG_ANY, "over_db_config(): "
  76                                                         "warning, freshly added "
  77                                                         "overlay #%d \"%s\" is already in list\n",
  78                                                         i, (*onp)->on_bi.bi_type, 0 );
  79
  80                                         /* NOTE: if the overlay already exists,
  81                                          * there is no way to merge the results
  82                                          * of the configuration that may have
  83                                          * occurred during bi_db_config(); we
  84                                          * just issue a warning, and the
  85                                          * administrator should deal with this */
  86                                 }
  87                         }
  88                         *onp = oi->oi_list;
  89
  90                         oi->oi_list = on2;
  91
  92                         ch_free( be->bd_info );
  93                 }
  94
  95                 be->bd_info = (BackendInfo *)oi;
  96                 if ( rc != SLAP_CONF_UNKNOWN ) return rc;
  97         }
  98
  99         ca.argv = argv;
 100         ca.argc = argc;
 101         ca.fname = fname;
 102         ca.lineno = lineno;
 103         ca.be = be;
 104         snprintf( ca.log, sizeof( ca.log ), "%s: line %d",
 105                         ca.fname, ca.lineno );
 106         ca.op = SLAP_CONFIG_ADD;
 107         ca.valx = -1;
 108
 109         for (; on; on=on->on_next) {
 110                 rc = SLAP_CONF_UNKNOWN;
 111                 if (on->on_bi.bi_cf_ocs) {
 112                         ConfigTable *ct;
 113                         ca.bi = &on->on_bi;
 114                         ct = config_find_keyword( on->on_bi.bi_cf_ocs->co_table, &ca );
 115                         if ( ct ) {
 116                                 ca.table = on->on_bi.bi_cf_ocs->co_type;
 117                                 rc = config_add_vals( ct, &ca );
 118                                 if ( rc != SLAP_CONF_UNKNOWN )
 119                                         break;
 120                         }
 121                 }
 122                 if (on->on_bi.bi_db_config && rc == SLAP_CONF_UNKNOWN) {
 123                         be->bd_info = &on->on_bi;
 124                         rc = on->on_bi.bi_db_config( be, fname, lineno,
 125                                 argc, argv );
 126                         if ( rc != SLAP_CONF_UNKNOWN ) break;
 127                 }
 128         }
 129         be->bd_info = bi_orig;
 130         be->be_cf_ocs = be_cf_ocs;
 131
 132         return rc;
 133 }
 134
 135 static int
 136 over_db_open(
 137         BackendDB *be,
 138         ConfigReply *cr
 139 )
 140 {
 141         slap_overinfo *oi = be->bd_info->bi_private;
 142         slap_overinst *on = oi->oi_list;
 143         BackendDB db = *be;
 144         int rc = 0;
 145
 146         db.be_flags |= SLAP_DBFLAG_OVERLAY;
 147         db.bd_info = oi->oi_orig;
 148         if ( db.bd_info->bi_db_open ) {
 149                 rc = db.bd_info->bi_db_open( &db, cr );
 150         }
 151
 152         for (; on && rc == 0; on=on->on_next) {
 153                 db.bd_info = &on->on_bi;
 154                 if ( db.bd_info->bi_db_open ) {
 155                         rc = db.bd_info->bi_db_open( &db, cr );
 156                 }
 157         }
 158
 159         return rc;
 160 }
 161
 162 static int
 163 over_db_close(
 164         BackendDB *be,
 165         ConfigReply *cr
 166 )
 167 {
 168         slap_overinfo *oi = be->bd_info->bi_private;
 169         slap_overinst *on = oi->oi_list;
 170         BackendInfo *bi_orig = be->bd_info;
 171         int rc = 0;
 172
 173         for (; on && rc == 0; on=on->on_next) {
 174                 be->bd_info = &on->on_bi;
 175                 if ( be->bd_info->bi_db_close ) {
 176                         rc = be->bd_info->bi_db_close( be, cr );
 177                 }
 178         }
 179
 180         if ( oi->oi_orig->bi_db_close ) {
 181                 be->bd_info = oi->oi_orig;
 182                 rc = be->bd_info->bi_db_close( be, cr );
 183         }
 184
 185         be->bd_info = bi_orig;
 186         return rc;
 187 }
 188
 189 static int
 190 over_db_destroy(
 191         BackendDB *be,
 192         ConfigReply *cr
 193 )
 194 {
 195         slap_overinfo *oi = be->bd_info->bi_private;
 196         slap_overinst *on = oi->oi_list, *next;
 197         BackendInfo *bi_orig = be->bd_info;
 198         int rc = 0;
 199
 200         be->bd_info = oi->oi_orig;
 201         if ( be->bd_info->bi_db_destroy ) {
 202                 rc = be->bd_info->bi_db_destroy( be, cr );
 203         }
 204
 205         for (; on && rc == 0; on=on->on_next) {
 206                 be->bd_info = &on->on_bi;
 207                 if ( be->bd_info->bi_db_destroy ) {
 208                         rc = be->bd_info->bi_db_destroy( be, cr );
 209                 }
 210         }
 211
 212         on = oi->oi_list;
 213         if ( on ) {
 214                 for (next = on->on_next; on; on=next) {
 215                         next = on->on_next;
 216                         free( on );
 217                 }
 218         }
 219         be->bd_info = bi_orig;
 220         free( oi );
 221         return rc;
 222 }
 223
 224 static int
 225 over_back_response ( Operation *op, SlapReply *rs )
 226 {
 227         slap_overinfo *oi = op->o_callback->sc_private;
 228         slap_overinst *on = oi->oi_list;
 229         int rc = SLAP_CB_CONTINUE;
 230         BackendDB *be = op->o_bd, db = *op->o_bd;
 231
 232         db.be_flags |= SLAP_DBFLAG_OVERLAY;
 233         op->o_bd = &db;
 234         for (; on; on=on->on_next ) {
 235                 if ( on->on_response ) {
 236                         db.bd_info = (BackendInfo *)on;
 237                         rc = on->on_response( op, rs );
 238                         if ( rc != SLAP_CB_CONTINUE ) break;
 239                 }
 240         }
 241         /* Bypass the remaining on_response layers, but allow
 242          * normal execution to continue.
 243          */
 244         if ( rc == SLAP_CB_BYPASS )
 245                 rc = SLAP_CB_CONTINUE;
 246         op->o_bd = be;
 247         return rc;
 248 }
 249
 250 static int
 251 over_access_allowed(
 252         Operation               *op,
 253         Entry                   *e,
 254         AttributeDescription    *desc,
 255         struct berval           *val,
 256         slap_access_t           access,
 257         AccessControlState      *state,
 258         slap_mask_t             *maskp )
 259 {
 260         slap_overinfo *oi;
 261         slap_overinst *on;
 262         BackendInfo *bi;
 263         BackendDB *be = op->o_bd, db;
 264         int rc = SLAP_CB_CONTINUE;
 265
 266         /* FIXME: used to happen for instance during abandon
 267          * when global overlays are used... */
 268         assert( op->o_bd != NULL );
 269
 270         bi = op->o_bd->bd_info;
 271         /* Were we invoked on the frontend? */
 272         if ( !bi->bi_access_allowed ) {
 273                 oi = frontendDB->bd_info->bi_private;
 274         } else {
 275                 oi = op->o_bd->bd_info->bi_private;
 276         }
 277         on = oi->oi_list;
 278
 279         for ( ; on; on = on->on_next ) {
 280                 if ( on->on_bi.bi_access_allowed ) {
 281                         /* NOTE: do not copy the structure until required */
 282                         if ( !SLAP_ISOVERLAY( op->o_bd ) ) {
 283                                 db = *op->o_bd;
 284                                 db.be_flags |= SLAP_DBFLAG_OVERLAY;
 285                                 op->o_bd = &db;
 286                         }
 287
 288                         op->o_bd->bd_info = (BackendInfo *)on;
 289                         rc = on->on_bi.bi_access_allowed( op, e,
 290                                 desc, val, access, state, maskp );
 291                         if ( rc != SLAP_CB_CONTINUE ) break;
 292                 }
 293         }
 294
 295         if ( rc == SLAP_CB_CONTINUE ) {
 296                 BI_access_allowed       *bi_access_allowed;
 297
 298                 /* if the database structure was changed, o_bd points to a
 299                  * copy of the structure; put the original bd_info in place */
 300                 if ( SLAP_ISOVERLAY( op->o_bd ) ) {
 301                         op->o_bd->bd_info = oi->oi_orig;
 302                 }
 303
 304                 if ( oi->oi_orig->bi_access_allowed ) {
 305                         bi_access_allowed = oi->oi_orig->bi_access_allowed;
 306                 } else {
 307                         bi_access_allowed = slap_access_allowed;
 308                 }
 309
 310                 rc = bi_access_allowed( op, e,
 311                         desc, val, access, state, maskp );
 312         }
 313         /* should not fall thru this far without anything happening... */
 314         if ( rc == SLAP_CB_CONTINUE ) {
 315                 /* access not allowed */
 316                 rc = 0;
 317         }
 318
 319         op->o_bd = be;
 320         op->o_bd->bd_info = bi;
 321
 322         return rc;
 323 }
 324
 325 int
 326 overlay_entry_get_ov(
 327         Operation               *op,
 328         struct berval   *dn,
 329         ObjectClass             *oc,
 330         AttributeDescription    *ad,
 331         int     rw,
 332         Entry   **e,
 333         slap_overinst *on )
 334 {
 335         slap_overinfo *oi = on->on_info;
 336         BackendDB *be = op->o_bd, db;
 337         BackendInfo *bi = op->o_bd->bd_info;
 338         int rc = SLAP_CB_CONTINUE;
 339
 340         for ( ; on; on = on->on_next ) {
 341                 if ( on->on_bi.bi_entry_get_rw ) {
 342                         /* NOTE: do not copy the structure until required */
 343                         if ( !SLAP_ISOVERLAY( op->o_bd ) ) {
 344                                 db = *op->o_bd;
 345                                 db.be_flags |= SLAP_DBFLAG_OVERLAY;
 346                                 op->o_bd = &db;
 347                         }
 348
 349                         op->o_bd->bd_info = (BackendInfo *)on;
 350                         rc = on->on_bi.bi_entry_get_rw( op, dn,
 351                                 oc, ad, rw, e );
 352                         if ( rc != SLAP_CB_CONTINUE ) break;
 353                 }
 354         }
 355
 356         if ( rc == SLAP_CB_CONTINUE ) {
 357                 /* if the database structure was changed, o_bd points to a
 358                  * copy of the structure; put the original bd_info in place */
 359                 if ( SLAP_ISOVERLAY( op->o_bd ) ) {
 360                         op->o_bd->bd_info = oi->oi_orig;
 361                 }
 362
 363                 if ( oi->oi_orig->bi_entry_get_rw ) {
 364                         rc = oi->oi_orig->bi_entry_get_rw( op, dn,
 365                                 oc, ad, rw, e );
 366                 }
 367         }
 368         /* should not fall thru this far without anything happening... */
 369         if ( rc == SLAP_CB_CONTINUE ) {
 370                 rc = LDAP_UNWILLING_TO_PERFORM;
 371         }
 372
 373         op->o_bd = be;
 374         op->o_bd->bd_info = bi;
 375
 376         return rc;
 377 }
 378
 379 static int
 380 over_entry_get_rw(
 381         Operation               *op,
 382         struct berval   *dn,
 383         ObjectClass             *oc,
 384         AttributeDescription    *ad,
 385         int     rw,
 386         Entry   **e )
 387 {
 388         slap_overinfo *oi;
 389         slap_overinst *on;
 390
 391         assert( op->o_bd != NULL );
 392
 393         oi = op->o_bd->bd_info->bi_private;
 394         on = oi->oi_list;
 395
 396         return overlay_entry_get_ov( op, dn, oc, ad, rw, e, on );
 397 }
 398
 399 int
 400 overlay_entry_release_ov(
 401         Operation       *op,
 402         Entry   *e,
 403         int rw,
 404         slap_overinst *on )
 405 {
 406         slap_overinfo *oi = on->on_info;
 407         BackendDB *be = op->o_bd, db;
 408         BackendInfo *bi = op->o_bd->bd_info;
 409         int rc = SLAP_CB_CONTINUE;
 410
 411         for ( ; on; on = on->on_next ) {
 412                 if ( on->on_bi.bi_entry_release_rw ) {
 413                         /* NOTE: do not copy the structure until required */
 414                         if ( !SLAP_ISOVERLAY( op->o_bd ) ) {
 415                                 db = *op->o_bd;
 416                                 db.be_flags |= SLAP_DBFLAG_OVERLAY;
 417                                 op->o_bd = &db;
 418                         }
 419
 420                         op->o_bd->bd_info = (BackendInfo *)on;
 421                         rc = on->on_bi.bi_entry_release_rw( op, e, rw );
 422                         if ( rc != SLAP_CB_CONTINUE ) break;
 423                 }
 424         }
 425
 426         if ( rc == SLAP_CB_CONTINUE ) {
 427                 /* if the database structure was changed, o_bd points to a
 428                  * copy of the structure; put the original bd_info in place */
 429                 if ( SLAP_ISOVERLAY( op->o_bd ) ) {
 430                         op->o_bd->bd_info = oi->oi_orig;
 431                 }
 432
 433                 if ( oi->oi_orig->bi_entry_release_rw ) {
 434                         rc = oi->oi_orig->bi_entry_release_rw( op, e, rw );
 435                 }
 436         }
 437         /* should not fall thru this far without anything happening... */
 438         if ( rc == SLAP_CB_CONTINUE ) {
 439                 entry_free( e );
 440                 rc = 0;
 441         }
 442
 443         op->o_bd = be;
 444         op->o_bd->bd_info = bi;
 445
 446         return rc;
 447 }
 448
 449 static int
 450 over_entry_release_rw(
 451         Operation       *op,
 452         Entry   *e,
 453         int rw )
 454 {
 455         slap_overinfo *oi;
 456         slap_overinst *on;
 457
 458         assert( op->o_bd != NULL );
 459
 460         oi = op->o_bd->bd_info->bi_private;
 461         on = oi->oi_list;
 462
 463         return overlay_entry_release_ov( op, e, rw, on );
 464 }
 465
 466 static int
 467 over_acl_group(
 468         Operation               *op,
 469         Entry                   *e,
 470         struct berval           *gr_ndn,
 471         struct berval           *op_ndn,
 472         ObjectClass             *group_oc,
 473         AttributeDescription    *group_at )
 474 {
 475         slap_overinfo *oi;
 476         slap_overinst *on;
 477         BackendInfo *bi = op->o_bd->bd_info;
 478         BackendDB *be = op->o_bd, db;
 479         int rc = SLAP_CB_CONTINUE;
 480
 481         /* FIXME: used to happen for instance during abandon
 482          * when global overlays are used... */
 483         assert( op->o_bd != NULL );
 484
 485         oi = op->o_bd->bd_info->bi_private;
 486         on = oi->oi_list;
 487
 488         for ( ; on; on = on->on_next ) {
 489                 if ( on->on_bi.bi_acl_group ) {
 490                         /* NOTE: do not copy the structure until required */
 491                         if ( !SLAP_ISOVERLAY( op->o_bd ) ) {
 492                                 db = *op->o_bd;
 493                                 db.be_flags |= SLAP_DBFLAG_OVERLAY;
 494                                 op->o_bd = &db;
 495                         }
 496
 497                         op->o_bd->bd_info = (BackendInfo *)on;
 498                         rc = on->on_bi.bi_acl_group( op, e,
 499                                 gr_ndn, op_ndn, group_oc, group_at );
 500                         if ( rc != SLAP_CB_CONTINUE ) break;
 501                 }
 502         }
 503
 504         if ( rc == SLAP_CB_CONTINUE ) {
 505                 BI_acl_group            *bi_acl_group;
 506
 507                 /* if the database structure was changed, o_bd points to a
 508                  * copy of the structure; put the original bd_info in place */
 509                 if ( SLAP_ISOVERLAY( op->o_bd ) ) {
 510                         op->o_bd->bd_info = oi->oi_orig;
 511                 }
 512
 513                 if ( oi->oi_orig->bi_acl_group ) {
 514                         bi_acl_group = oi->oi_orig->bi_acl_group;
 515                 } else {
 516                         bi_acl_group = backend_group;
 517                 }
 518
 519                 rc = bi_acl_group( op, e,
 520                         gr_ndn, op_ndn, group_oc, group_at );
 521         }
 522         /* should not fall thru this far without anything happening... */
 523         if ( rc == SLAP_CB_CONTINUE ) {
 524                 /* access not allowed */
 525                 rc = 0;
 526         }
 527
 528         op->o_bd = be;
 529         op->o_bd->bd_info = bi;
 530
 531         return rc;
 532 }
 533
 534 static int
 535 over_acl_attribute(
 536         Operation               *op,
 537         Entry                   *target,
 538         struct berval           *entry_ndn,
 539         AttributeDescription    *entry_at,
 540         BerVarray               *vals,
 541         slap_access_t           access )
 542 {
 543         slap_overinfo *oi;
 544         slap_overinst *on;
 545         BackendInfo *bi = op->o_bd->bd_info;
 546         BackendDB *be = op->o_bd, db;
 547         int rc = SLAP_CB_CONTINUE;
 548
 549         /* FIXME: used to happen for instance during abandon
 550          * when global overlays are used... */
 551         assert( op->o_bd != NULL );
 552
 553         oi = op->o_bd->bd_info->bi_private;
 554         on = oi->oi_list;
 555
 556         for ( ; on; on = on->on_next ) {
 557                 if ( on->on_bi.bi_acl_attribute ) {
 558                         /* NOTE: do not copy the structure until required */
 559                         if ( !SLAP_ISOVERLAY( op->o_bd ) ) {
 560                                 db = *op->o_bd;
 561                                 db.be_flags |= SLAP_DBFLAG_OVERLAY;
 562                                 op->o_bd = &db;
 563                         }
 564
 565                         op->o_bd->bd_info = (BackendInfo *)on;
 566                         rc = on->on_bi.bi_acl_attribute( op, target,
 567                                 entry_ndn, entry_at, vals, access );
 568                         if ( rc != SLAP_CB_CONTINUE ) break;
 569                 }
 570         }
 571
 572         if ( rc == SLAP_CB_CONTINUE ) {
 573                 BI_acl_attribute                *bi_acl_attribute;
 574
 575                 /* if the database structure was changed, o_bd points to a
 576                  * copy of the structure; put the original bd_info in place */
 577                 if ( SLAP_ISOVERLAY( op->o_bd ) ) {
 578                         op->o_bd->bd_info = oi->oi_orig;
 579                 }
 580
 581                 if ( oi->oi_orig->bi_acl_attribute ) {
 582                         bi_acl_attribute = oi->oi_orig->bi_acl_attribute;
 583                 } else {
 584                         bi_acl_attribute = backend_attribute;
 585                 }
 586
 587                 rc = bi_acl_attribute( op, target,
 588                         entry_ndn, entry_at, vals, access );
 589         }
 590         /* should not fall thru this far without anything happening... */
 591         if ( rc == SLAP_CB_CONTINUE ) {
 592                 /* access not allowed */
 593                 rc = 0;
 594         }
 595
 596         op->o_bd = be;
 597         op->o_bd->bd_info = bi;
 598
 599         return rc;
 600 }
 601
 602 int
 603 overlay_callback_after_backover( Operation *op, slap_callback *sc, int append )
 604 {
 605         slap_callback **scp;
 606
 607         for ( scp = &op->o_callback; *scp != NULL; scp = &(*scp)->sc_next ) {
 608                 if ( (*scp)->sc_response == over_back_response ) {
 609                         sc->sc_next = (*scp)->sc_next;
 610                         (*scp)->sc_next = sc;
 611                         return 0;
 612                 }
 613         }
 614
 615         if ( append ) {
 616                 *scp = sc;
 617                 return 0;
 618         }
 619
 620         return 1;
 621 }
 622
 623 /*
 624  * default return code in case of missing backend function
 625  * and overlay stack returning SLAP_CB_CONTINUE
 626  */
 627 static int op_rc[ op_last ] = {
 628         LDAP_UNWILLING_TO_PERFORM,      /* bind */
 629         LDAP_UNWILLING_TO_PERFORM,      /* unbind */
 630         LDAP_UNWILLING_TO_PERFORM,      /* search */
 631         SLAP_CB_CONTINUE,               /* compare; pass to frontend */
 632         LDAP_UNWILLING_TO_PERFORM,      /* modify */
 633         LDAP_UNWILLING_TO_PERFORM,      /* modrdn */
 634         LDAP_UNWILLING_TO_PERFORM,      /* add */
 635         LDAP_UNWILLING_TO_PERFORM,      /* delete */
 636         LDAP_UNWILLING_TO_PERFORM,      /* abandon */
 637         LDAP_UNWILLING_TO_PERFORM,      /* cancel */
 638         LDAP_UNWILLING_TO_PERFORM,      /* extended */
 639         LDAP_SUCCESS,                   /* aux_operational */
 640         LDAP_SUCCESS,                   /* aux_chk_referrals */
 641         SLAP_CB_CONTINUE                /* aux_chk_controls; pass to frontend */
 642 };
 643
 644 int overlay_op_walk(
 645         Operation *op,
 646         SlapReply *rs,
 647         slap_operation_t which,
 648         slap_overinfo *oi,
 649         slap_overinst *on
 650 )
 651 {
 652         BI_op_bind **func;
 653         int rc = SLAP_CB_CONTINUE;
 654
 655         for (; on; on=on->on_next ) {
 656                 func = &on->on_bi.bi_op_bind;
 657                 if ( func[which] ) {
 658                         op->o_bd->bd_info = (BackendInfo *)on;
 659                         rc = func[which]( op, rs );
 660                         if ( rc != SLAP_CB_CONTINUE ) break;
 661                 }
 662         }
 663         if ( rc == SLAP_CB_BYPASS )
 664                 rc = SLAP_CB_CONTINUE;
 665
 666         func = &oi->oi_orig->bi_op_bind;
 667         if ( func[which] && rc == SLAP_CB_CONTINUE ) {
 668                 op->o_bd->bd_info = oi->oi_orig;
 669                 rc = func[which]( op, rs );
 670         }
 671         /* should not fall thru this far without anything happening... */
 672         if ( rc == SLAP_CB_CONTINUE ) {
 673                 rc = op_rc[ which ];
 674         }
 675
 676         /* The underlying backend didn't handle the request, make sure
 677          * overlay cleanup is processed.
 678          */
 679         if ( rc == LDAP_UNWILLING_TO_PERFORM ) {
 680                 slap_callback *sc_next;
 681                 for ( ; op->o_callback && op->o_callback->sc_response !=
 682                         over_back_response; op->o_callback = sc_next ) {
 683                         sc_next = op->o_callback->sc_next;
 684                         if ( op->o_callback->sc_cleanup ) {
 685                                 op->o_callback->sc_cleanup( op, rs );
 686                         }
 687                 }
 688         }
 689         return rc;
 690 }
 691
 692 static int
 693 over_op_func(
 694         Operation *op,
 695         SlapReply *rs,
 696         slap_operation_t which
 697 )
 698 {
 699         slap_overinfo *oi;
 700         slap_overinst *on;
 701         BackendDB *be = op->o_bd, db;
 702         slap_callback cb = {NULL, over_back_response, NULL, NULL}, **sc;
 703         int rc = SLAP_CB_CONTINUE;
 704
 705         /* FIXME: used to happen for instance during abandon
 706          * when global overlays are used... */
 707         assert( op->o_bd != NULL );
 708
 709         oi = op->o_bd->bd_info->bi_private;
 710         on = oi->oi_list;
 711
 712         if ( !SLAP_ISOVERLAY( op->o_bd )) {
 713                 db = *op->o_bd;
 714                 db.be_flags |= SLAP_DBFLAG_OVERLAY;
 715                 op->o_bd = &db;
 716         }
 717         cb.sc_next = op->o_callback;
 718         cb.sc_private = oi;
 719         op->o_callback = &cb;
 720
 721         rc = overlay_op_walk( op, rs, which, oi, on );
 722         for ( sc = &op->o_callback; *sc; sc = &(*sc)->sc_next ) {
 723                 if ( *sc == &cb ) {
 724                         *sc = cb.sc_next;
 725                         break;
 726                 }
 727         }
 728
 729         op->o_bd = be;
 730         return rc;
 731 }
 732
 733 static int
 734 over_op_bind( Operation *op, SlapReply *rs )
 735 {
 736         return over_op_func( op, rs, op_bind );
 737 }
 738
 739 static int
 740 over_op_unbind( Operation *op, SlapReply *rs )
 741 {
 742         return over_op_func( op, rs, op_unbind );
 743 }
 744
 745 static int
 746 over_op_search( Operation *op, SlapReply *rs )
 747 {
 748         return over_op_func( op, rs, op_search );
 749 }
 750
 751 static int
 752 over_op_compare( Operation *op, SlapReply *rs )
 753 {
 754         return over_op_func( op, rs, op_compare );
 755 }
 756
 757 static int
 758 over_op_modify( Operation *op, SlapReply *rs )
 759 {
 760         return over_op_func( op, rs, op_modify );
 761 }
 762
 763 static int
 764 over_op_modrdn( Operation *op, SlapReply *rs )
 765 {
 766         return over_op_func( op, rs, op_modrdn );
 767 }
 768
 769 static int
 770 over_op_add( Operation *op, SlapReply *rs )
 771 {
 772         return over_op_func( op, rs, op_add );
 773 }
 774
 775 static int
 776 over_op_delete( Operation *op, SlapReply *rs )
 777 {
 778         return over_op_func( op, rs, op_delete );
 779 }
 780
 781 static int
 782 over_op_abandon( Operation *op, SlapReply *rs )
 783 {
 784         return over_op_func( op, rs, op_abandon );
 785 }
 786
 787 static int
 788 over_op_cancel( Operation *op, SlapReply *rs )
 789 {
 790         return over_op_func( op, rs, op_cancel );
 791 }
 792
 793 static int
 794 over_op_extended( Operation *op, SlapReply *rs )
 795 {
 796         return over_op_func( op, rs, op_extended );
 797 }
 798
 799 static int
 800 over_aux_operational( Operation *op, SlapReply *rs )
 801 {
 802         return over_op_func( op, rs, op_aux_operational );
 803 }
 804
 805 static int
 806 over_aux_chk_referrals( Operation *op, SlapReply *rs )
 807 {
 808         return over_op_func( op, rs, op_aux_chk_referrals );
 809 }
 810
 811 static int
 812 over_aux_chk_controls( Operation *op, SlapReply *rs )
 813 {
 814         return over_op_func( op, rs, op_aux_chk_controls );
 815 }
 816
 817 enum conn_which {
 818         conn_init = 0,
 819         conn_destroy,
 820         conn_last
 821 };
 822
 823 static int
 824 over_connection_func(
 825         BackendDB       *bd,
 826         Connection      *conn,
 827         enum conn_which which
 828 )
 829 {
 830         slap_overinfo           *oi;
 831         slap_overinst           *on;
 832         BackendDB               db;
 833         int                     rc = SLAP_CB_CONTINUE;
 834         BI_connection_init      **func;
 835
 836         /* FIXME: used to happen for instance during abandon
 837          * when global overlays are used... */
 838         assert( bd != NULL );
 839
 840         oi = bd->bd_info->bi_private;
 841         on = oi->oi_list;
 842
 843         if ( !SLAP_ISOVERLAY( bd ) ) {
 844                 db = *bd;
 845                 db.be_flags |= SLAP_DBFLAG_OVERLAY;
 846                 bd = &db;
 847         }
 848
 849         for ( ; on; on = on->on_next ) {
 850                 func = &on->on_bi.bi_connection_init;
 851                 if ( func[ which ] ) {
 852                         bd->bd_info = (BackendInfo *)on;
 853                         rc = func[ which ]( bd, conn );
 854                         if ( rc != SLAP_CB_CONTINUE ) break;
 855                 }
 856         }
 857
 858         func = &oi->oi_orig->bi_connection_init;
 859         if ( func[ which ] && rc == SLAP_CB_CONTINUE ) {
 860                 bd->bd_info = oi->oi_orig;
 861                 rc = func[ which ]( bd, conn );
 862         }
 863         /* should not fall thru this far without anything happening... */
 864         if ( rc == SLAP_CB_CONTINUE ) {
 865                 rc = LDAP_UNWILLING_TO_PERFORM;
 866         }
 867
 868         return rc;
 869 }
 870
 871 static int
 872 over_connection_init(
 873         BackendDB       *bd,
 874         Connection      *conn
 875 )
 876 {
 877         return over_connection_func( bd, conn, conn_init );
 878 }
 879
 880 static int
 881 over_connection_destroy(
 882         BackendDB       *bd,
 883         Connection      *conn
 884 )
 885 {
 886         return over_connection_func( bd, conn, conn_destroy );
 887 }
 888
 889 int
 890 overlay_register(
 891         slap_overinst *on
 892 )
 893 {
 894         slap_overinst   *tmp;
 895
 896         /* FIXME: check for duplicates? */
 897         for ( tmp = overlays; tmp != NULL; tmp = tmp->on_next ) {
 898                 if ( strcmp( on->on_bi.bi_type, tmp->on_bi.bi_type ) == 0 ) {
 899                         Debug( LDAP_DEBUG_ANY,
 900                                 "overlay_register(\"%s\"): "
 901                                 "name already in use.\n",
 902                                 on->on_bi.bi_type, 0, 0 );
 903                         return -1;
 904                 }
 905
 906                 if ( on->on_bi.bi_obsolete_names != NULL ) {
 907                         int     i;
 908
 909                         for ( i = 0; on->on_bi.bi_obsolete_names[ i ] != NULL; i++ ) {
 910                                 if ( strcmp( on->on_bi.bi_obsolete_names[ i ], tmp->on_bi.bi_type ) == 0 ) {
 911                                         Debug( LDAP_DEBUG_ANY,
 912                                                 "overlay_register(\"%s\"): "
 913                                                 "obsolete name \"%s\" already in use "
 914                                                 "by overlay \"%s\".\n",
 915                                                 on->on_bi.bi_type,
 916                                                 on->on_bi.bi_obsolete_names[ i ],
 917                                                 tmp->on_bi.bi_type );
 918                                         return -1;
 919                                 }
 920                         }
 921                 }
 922
 923                 if ( tmp->on_bi.bi_obsolete_names != NULL ) {
 924                         int     i;
 925
 926                         for ( i = 0; tmp->on_bi.bi_obsolete_names[ i ] != NULL; i++ ) {
 927                                 int     j;
 928
 929                                 if ( strcmp( on->on_bi.bi_type, tmp->on_bi.bi_obsolete_names[ i ] ) == 0 ) {
 930                                         Debug( LDAP_DEBUG_ANY,
 931                                                 "overlay_register(\"%s\"): "
 932                                                 "name already in use "
 933                                                 "as obsolete by overlay \"%s\".\n",
 934                                                 on->on_bi.bi_type,
 935                                                 tmp->on_bi.bi_obsolete_names[ i ], 0 );
 936                                         return -1;
 937                                 }
 938
 939                                 if ( on->on_bi.bi_obsolete_names != NULL ) {
 940                                         for ( j = 0; on->on_bi.bi_obsolete_names[ j ] != NULL; j++ ) {
 941                                                 if ( strcmp( on->on_bi.bi_obsolete_names[ j ], tmp->on_bi.bi_obsolete_names[ i ] ) == 0 ) {
 942                                                         Debug( LDAP_DEBUG_ANY,
 943                                                                 "overlay_register(\"%s\"): "
 944                                                                 "obsolete name \"%s\" already in use "
 945                                                                 "as obsolete by overlay \"%s\".\n",
 946                                                                 on->on_bi.bi_type,
 947                                                                 on->on_bi.bi_obsolete_names[ j ],
 948                                                                 tmp->on_bi.bi_type );
 949                                                         return -1;
 950                                                 }
 951                                         }
 952                                 }
 953                         }
 954                 }
 955         }
 956
 957         on->on_next = overlays;
 958         overlays = on;
 959         return 0;
 960 }
 961
 962 /*
 963  * iterator on registered overlays; overlay_next( NULL ) returns the first
 964  * overlay; subsequent calls with the previously returned value allow to
 965  * iterate over the entire list; returns NULL when no more overlays are
 966  * registered.
 967  */
 968
 969 slap_overinst *
 970 overlay_next(
 971         slap_overinst *on
 972 )
 973 {
 974         if ( on == NULL ) {
 975                 return overlays;
 976         }
 977
 978         return on->on_next;
 979 }
 980
 981 /*
 982  * returns a specific registered overlay based on the type; NULL if not
 983  * registered.
 984  */
 985
 986 slap_overinst *
 987 overlay_find( const char *over_type )
 988 {
 989         slap_overinst *on = overlays;
 990
 991         assert( over_type != NULL );
 992
 993         for ( ; on; on = on->on_next ) {
 994                 if ( strcmp( on->on_bi.bi_type, over_type ) == 0 ) {
 995                         goto foundit;
 996                 }
 997
 998                 if ( on->on_bi.bi_obsolete_names != NULL ) {
 999                         int     i;
1000
1001                         for ( i = 0; on->on_bi.bi_obsolete_names[ i ] != NULL; i++ ) {
1002                                 if ( strcmp( on->on_bi.bi_obsolete_names[ i ], over_type ) == 0 ) {
1003                                         Debug( LDAP_DEBUG_ANY,
1004                                                 "overlay_find(\"%s\"): "
1005                                                 "obsolete name for \"%s\".\n",
1006                                                 on->on_bi.bi_obsolete_names[ i ],
1007                                                 on->on_bi.bi_type, 0 );
1008                                         goto foundit;
1009                                 }
1010                         }
1011                 }
1012         }
1013
1014 foundit:;
1015         return on;
1016 }
1017
1018 static const char overtype[] = "over";
1019
1020 /*
1021  * returns TRUE (1) if the database is actually an overlay instance;
1022  * FALSE (0) otherwise.
1023  */
1024
1025 int
1026 overlay_is_over( BackendDB *be )
1027 {
1028         return be->bd_info->bi_type == overtype;
1029 }
1030
1031 /*
1032  * returns TRUE (1) if the given database is actually an overlay
1033  * instance and, somewhere in the list, contains the requested overlay;
1034  * FALSE (0) otherwise.
1035  */
1036
1037 int
1038 overlay_is_inst( BackendDB *be, const char *over_type )
1039 {
1040         slap_overinst   *on;
1041
1042         assert( be != NULL );
1043
1044         if ( !overlay_is_over( be ) ) {
1045                 return 0;
1046         }
1047
1048         on = ((slap_overinfo *)be->bd_info->bi_private)->oi_list;
1049         for ( ; on; on = on->on_next ) {
1050                 if ( strcmp( on->on_bi.bi_type, over_type ) == 0 ) {
1051                         return 1;
1052                 }
1053         }
1054
1055         return 0;
1056 }
1057
1058 int
1059 overlay_register_control( BackendDB *be, const char *oid )
1060 {
1061         int             gotit = 0;
1062         int             cid;
1063
1064         if ( slap_find_control_id( oid, &cid ) == LDAP_CONTROL_NOT_FOUND ) {
1065                 return -1;
1066         }
1067
1068         if ( SLAP_ISGLOBALOVERLAY( be ) ) {
1069                 BackendDB *bd;
1070
1071                 /* add to all backends... */
1072                 LDAP_STAILQ_FOREACH( bd, &backendDB, be_next ) {
1073                         if ( bd == be->bd_self ) {
1074                                 gotit = 1;
1075                         }
1076
1077                         /* overlays can be instanciated multiple times, use
1078                          * be_ctrls[ cid ] as an instance counter, so that the
1079                          * overlay's controls are only really disabled after the
1080                          * last instance called overlay_register_control() */
1081                         bd->be_ctrls[ cid ]++;
1082                         bd->be_ctrls[ SLAP_MAX_CIDS ] = 1;
1083                 }
1084
1085         }
1086
1087         if ( !gotit ) {
1088                 /* overlays can be instanciated multiple times, use
1089                  * be_ctrls[ cid ] as an instance counter, so that the
1090                  * overlay's controls are only really unregistered after the
1091                  * last instance called overlay_register_control() */
1092                 be->bd_self->be_ctrls[ cid ]++;
1093                 be->bd_self->be_ctrls[ SLAP_MAX_CIDS ] = 1;
1094         }
1095
1096         return 0;
1097 }
1098
1099 #ifdef SLAP_CONFIG_DELETE
1100 void
1101 overlay_unregister_control( BackendDB *be, const char *oid )
1102 {
1103         int             gotit = 0;
1104         int             cid;
1105
1106         if ( slap_find_control_id( oid, &cid ) == LDAP_CONTROL_NOT_FOUND ) {
1107                 return;
1108         }
1109
1110         if ( SLAP_ISGLOBALOVERLAY( be ) ) {
1111                 BackendDB *bd;
1112
1113                 /* remove from all backends... */
1114                 LDAP_STAILQ_FOREACH( bd, &backendDB, be_next ) {
1115                         if ( bd == be->bd_self ) {
1116                                 gotit = 1;
1117                         }
1118
1119                         bd->be_ctrls[ cid ]--;
1120                 }
1121         }
1122
1123         if ( !gotit ) {
1124                 be->bd_self->be_ctrls[ cid ]--;
1125         }
1126 }
1127 #endif /* SLAP_CONFIG_DELETE */
1128
1129 void
1130 overlay_destroy_one( BackendDB *be, slap_overinst *on )
1131 {
1132         slap_overinfo *oi = on->on_info;
1133         slap_overinst **oidx;
1134
1135         for ( oidx = &oi->oi_list; *oidx; oidx = &(*oidx)->on_next ) {
1136                 if ( *oidx == on ) {
1137                         *oidx = on->on_next;
1138                         if ( on->on_bi.bi_db_destroy ) {
1139                                 BackendInfo *bi_orig = be->bd_info;
1140                                 be->bd_info = (BackendInfo *)on;
1141                                 on->on_bi.bi_db_destroy( be, NULL );
1142                                 be->bd_info = bi_orig;
1143                         }
1144                         free( on );
1145                         break;
1146                 }
1147         }
1148 }
1149
1150 #ifdef SLAP_CONFIG_DELETE
1151 void
1152 overlay_remove( BackendDB *be, slap_overinst *on )
1153 {
1154         slap_overinfo *oi = on->on_info;
1155         slap_overinst **oidx;
1156         BackendInfo *bi_orig;
1157
1158         /* remove overlay from oi_list an call db_close and db_destroy
1159          * handlers */
1160         for ( oidx = &oi->oi_list; *oidx; oidx = &(*oidx)->on_next ) {
1161                 if ( *oidx == on ) {
1162                         *oidx = on->on_next;
1163                         bi_orig = be->bd_info;
1164                         be->bd_info = (BackendInfo *)on;
1165                         if ( on->on_bi.bi_db_close ) {
1166                                 on->on_bi.bi_db_close( be, NULL );
1167                         }
1168                         if ( on->on_bi.bi_db_destroy ) {
1169                                 on->on_bi.bi_db_destroy( be, NULL );
1170                         }
1171                         be->bd_info = bi_orig;
1172                         free( on );
1173                         break;
1174                 }
1175         }
1176
1177         /* clean up after removing last overlay */
1178         if ( ! oi->oi_list )
1179         {
1180                 /* reset db flags and bd_info to orig */
1181                 be->bd_info = oi->oi_orig;
1182                 ch_free(oi);
1183         }
1184 }
1185 #endif /* SLAP_CONFIG_DELETE */
1186
1187 void
1188 overlay_insert( BackendDB *be, slap_overinst *on2, slap_overinst ***prev,
1189         int idx )
1190 {
1191         slap_overinfo *oi = (slap_overinfo *)be->bd_info;
1192
1193         if ( idx == -1 ) {
1194                 on2->on_next = oi->oi_list;
1195                 oi->oi_list = on2;
1196         } else {
1197                 int i;
1198                 slap_overinst *on, *otmp1 = NULL, *otmp2;
1199
1200                 /* Since the list is in reverse order and is singly linked,
1201                  * we reverse it to find the idx insertion point. Adding
1202                  * on overlay at a specific point should be a pretty
1203                  * infrequent occurrence.
1204                  */
1205                 for ( on = oi->oi_list; on; on=otmp2 ) {
1206                         otmp2 = on->on_next;
1207                         on->on_next = otmp1;
1208                         otmp1 = on;
1209                 }
1210                 oi->oi_list = NULL;
1211                 /* advance to insertion point */
1212                 for ( i=0, on = otmp1; i<idx; i++ ) {
1213                         otmp1 = on->on_next;
1214                         on->on_next = oi->oi_list;
1215                         oi->oi_list = on;
1216                 }
1217                 /* insert */
1218                 on2->on_next = oi->oi_list;
1219                 oi->oi_list = on2;
1220                 if ( otmp1 ) {
1221                         *prev = &otmp1->on_next;
1222                         /* replace remainder of list */
1223                         for ( on=otmp1; on; on=otmp1 ) {
1224                                 otmp1 = on->on_next;
1225                                 on->on_next = oi->oi_list;
1226                                 oi->oi_list = on;
1227                         }
1228                 }
1229         }
1230 }
1231
1232 void
1233 overlay_move( BackendDB *be, slap_overinst *on, int idx )
1234 {
1235         slap_overinfo *oi = (slap_overinfo *)be->bd_info;
1236         slap_overinst **onp;
1237
1238         for (onp = &oi->oi_list; *onp; onp= &(*onp)->on_next) {
1239                 if ( *onp == on ) {
1240                         *onp = on->on_next;
1241                         break;
1242                 }
1243         }
1244         overlay_insert( be, on, &onp, idx );
1245 }
1246
1247 /* add an overlay to a particular backend. */
1248 int
1249 overlay_config( BackendDB *be, const char *ov, int idx, BackendInfo **res, ConfigReply *cr )
1250 {
1251         slap_overinst *on = NULL, *on2 = NULL, **prev;
1252         slap_overinfo *oi = NULL;
1253         BackendInfo *bi = NULL;
1254
1255         if ( res )
1256                 *res = NULL;
1257
1258         on = overlay_find( ov );
1259         if ( !on ) {
1260                 Debug( LDAP_DEBUG_ANY, "overlay \"%s\" not found\n", ov, 0, 0 );
1261                 return 1;
1262         }
1263
1264         /* If this is the first overlay on this backend, set up the
1265          * overlay info structure
1266          */
1267         if ( !overlay_is_over( be ) ) {
1268                 int     isglobal = 0;
1269
1270                 /* NOTE: the first time a global overlay is configured,
1271                  * frontendDB gets this flag; it is used later by overlays
1272                  * to determine if they're stacked on top of the frontendDB */
1273                 if ( be->bd_info == frontendDB->bd_info || SLAP_ISGLOBALOVERLAY( be ) ) {
1274                         isglobal = 1;
1275                         if ( on->on_bi.bi_flags & SLAPO_BFLAG_DBONLY ) {
1276                                 Debug( LDAP_DEBUG_ANY, "overlay_config(): "
1277                                         "overlay \"%s\" cannot be global.\n",
1278                                         ov, 0, 0 );
1279                                 return 1;
1280                         }
1281
1282                 } else if ( on->on_bi.bi_flags & SLAPO_BFLAG_GLOBONLY ) {
1283                         Debug( LDAP_DEBUG_ANY, "overlay_config(): "
1284                                 "overlay \"%s\" can only be global.\n",
1285                                 ov, 0, 0 );
1286                         return 1;
1287                 }
1288
1289                 oi = ch_malloc( sizeof( slap_overinfo ) );
1290                 oi->oi_orig = be->bd_info;
1291                 oi->oi_bi = *be->bd_info;
1292                 oi->oi_origdb = be;
1293
1294                 if ( isglobal ) {
1295                         SLAP_DBFLAGS( be ) |= SLAP_DBFLAG_GLOBAL_OVERLAY;
1296                 }
1297
1298                 /* Save a pointer to ourself in bi_private.
1299                  */
1300                 oi->oi_bi.bi_private = oi;
1301                 oi->oi_list = NULL;
1302                 bi = (BackendInfo *)oi;
1303
1304                 bi->bi_type = (char *)overtype;
1305
1306                 bi->bi_db_config = over_db_config;
1307                 bi->bi_db_open = over_db_open;
1308                 bi->bi_db_close = over_db_close;
1309                 bi->bi_db_destroy = over_db_destroy;
1310
1311                 bi->bi_op_bind = over_op_bind;
1312                 bi->bi_op_unbind = over_op_unbind;
1313                 bi->bi_op_search = over_op_search;
1314                 bi->bi_op_compare = over_op_compare;
1315                 bi->bi_op_modify = over_op_modify;
1316                 bi->bi_op_modrdn = over_op_modrdn;
1317                 bi->bi_op_add = over_op_add;
1318                 bi->bi_op_delete = over_op_delete;
1319                 bi->bi_op_abandon = over_op_abandon;
1320                 bi->bi_op_cancel = over_op_cancel;
1321
1322                 bi->bi_extended = over_op_extended;
1323
1324                 /*
1325                  * this is fine because it has the same
1326                  * args of the operations; we need to rework
1327                  * all the hooks to share the same args
1328                  * of the operations...
1329                  */
1330                 bi->bi_operational = over_aux_operational;
1331                 bi->bi_chk_referrals = over_aux_chk_referrals;
1332                 bi->bi_chk_controls = over_aux_chk_controls;
1333
1334                 /* these have specific arglists */
1335                 bi->bi_entry_get_rw = over_entry_get_rw;
1336                 bi->bi_entry_release_rw = over_entry_release_rw;
1337                 bi->bi_access_allowed = over_access_allowed;
1338                 bi->bi_acl_group = over_acl_group;
1339                 bi->bi_acl_attribute = over_acl_attribute;
1340
1341                 bi->bi_connection_init = over_connection_init;
1342                 bi->bi_connection_destroy = over_connection_destroy;
1343
1344                 be->bd_info = bi;
1345
1346         } else {
1347                 if ( overlay_is_inst( be, ov ) ) {
1348                         if ( SLAPO_SINGLE( be ) ) {
1349                                 Debug( LDAP_DEBUG_ANY, "overlay_config(): "
1350                                         "overlay \"%s\" already in list\n",
1351                                         ov, 0, 0 );
1352                                 return 1;
1353                         }
1354                 }
1355
1356                 oi = be->bd_info->bi_private;
1357         }
1358
1359         /* Insert new overlay into list. By default overlays are
1360          * added to head of list and executed in LIFO order.
1361          */
1362         on2 = ch_calloc( 1, sizeof(slap_overinst) );
1363         *on2 = *on;
1364         on2->on_info = oi;
1365
1366         prev = &oi->oi_list;
1367         /* Do we need to find the insertion point? */
1368         if ( idx >= 0 ) {
1369                 int i;
1370
1371                 /* count current overlays */
1372                 for ( i=0, on=oi->oi_list; on; on=on->on_next, i++ );
1373
1374                 /* are we just appending a new one? */
1375                 if ( idx >= i )
1376                         idx = -1;
1377         }
1378         overlay_insert( be, on2, &prev, idx );
1379
1380         /* Any initialization needed? */
1381         if ( on2->on_bi.bi_db_init ) {
1382                 int rc;
1383                 be->bd_info = (BackendInfo *)on2;
1384                 rc = on2->on_bi.bi_db_init( be, cr);
1385                 be->bd_info = (BackendInfo *)oi;
1386                 if ( rc ) {
1387                         *prev = on2->on_next;
1388                         ch_free( on2 );
1389                         on2 = NULL;
1390                         return rc;
1391                 }
1392         }
1393
1394         if ( res )
1395                 *res = &on2->on_bi;
1396
1397         return 0;
1398 }
1399