source3/smbd/notify.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    change notify handling
   4    Copyright (C) Andrew Tridgell 2000
   5    Copyright (C) Jeremy Allison 1994-1998
   6    Copyright (C) Volker Lendecke 2007
   7
   8    This program is free software; you can redistribute it and/or modify
   9    it under the terms of the GNU General Public License as published by
  10    the Free Software Foundation; either version 3 of the License, or
  11    (at your option) any later version.
  12
  13    This program is distributed in the hope that it will be useful,
  14    but WITHOUT ANY WARRANTY; without even the implied warranty of
  15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  16    GNU General Public License for more details.
  17
  18    You should have received a copy of the GNU General Public License
  19    along with this program.  If not, see <http://www.gnu.org/licenses/>.
  20 */
  21
  22 #include "includes.h"
  23 #include "smbd/smbd.h"
  24 #include "smbd/globals.h"
  25 #include "../librpc/gen_ndr/ndr_notify.h"
  26 #include "librpc/gen_ndr/ndr_file_id.h"
  27
  28 struct notify_change_event {
  29         struct timespec when;
  30         uint32_t action;
  31         const char *name;
  32 };
  33
  34 struct notify_change_buf {
  35         /*
  36          * Filters for reinitializing after notifyd has been restarted
  37          */
  38         uint32_t filter;
  39         uint32_t subdir_filter;
  40
  41         /*
  42          * If no requests are pending, changes are queued here. Simple array,
  43          * we only append.
  44          */
  45
  46         /*
  47          * num_changes == -1 means that we have got a catch-all change, when
  48          * asked we just return NT_STATUS_OK without specific changes.
  49          */
  50         int num_changes;
  51         struct notify_change_event *changes;
  52
  53         /*
  54          * If no changes are around requests are queued here. Using a linked
  55          * list, because we have to append at the end and delete from the top.
  56          */
  57         struct notify_change_request *requests;
  58 };
  59
  60 struct notify_change_request {
  61         struct notify_change_request *prev, *next;
  62         struct files_struct *fsp;       /* backpointer for cancel by mid */
  63         struct smb_request *req;
  64         uint32_t filter;
  65         uint32_t max_param;
  66         void (*reply_fn)(struct smb_request *req,
  67                          NTSTATUS error_code,
  68                          uint8_t *buf, size_t len);
  69         struct notify_mid_map *mid_map;
  70         void *backend_data;
  71 };
  72
  73 static void notify_fsp(files_struct *fsp, struct timespec when,
  74                        uint32_t action, const char *name);
  75
  76 bool change_notify_fsp_has_changes(struct files_struct *fsp)
  77 {
  78         if (fsp == NULL) {
  79                 return false;
  80         }
  81
  82         if (fsp->notify == NULL) {
  83                 return false;
  84         }
  85
  86         if (fsp->notify->num_changes == 0) {
  87                 return false;
  88         }
  89
  90         return true;
  91 }
  92
  93 /*
  94  * For NTCancel, we need to find the notify_change_request indexed by
  95  * mid. Separate list here.
  96  */
  97
  98 struct notify_mid_map {
  99         struct notify_mid_map *prev, *next;
 100         struct notify_change_request *req;
 101         uint64_t mid;
 102 };
 103
 104 static bool notify_change_record_identical(struct notify_change_event *c1,
 105                                            struct notify_change_event *c2)
 106 {
 107         /* Note this is deliberately case sensitive. */
 108         if (c1->action == c2->action &&
 109                         strcmp(c1->name, c2->name) == 0) {
 110                 return True;
 111         }
 112         return False;
 113 }
 114
 115 static int compare_notify_change_events(const void *p1, const void *p2)
 116 {
 117         const struct notify_change_event *e1 = p1;
 118         const struct notify_change_event *e2 = p2;
 119
 120         return timespec_compare(&e1->when, &e2->when);
 121 }
 122
 123 static bool notify_marshall_changes(int num_changes,
 124                                 uint32_t max_offset,
 125                                 struct notify_change_event *changes,
 126                                 DATA_BLOB *final_blob)
 127 {
 128         int i;
 129
 130         if (num_changes == -1) {
 131                 return false;
 132         }
 133
 134         /*
 135          * Sort the notifies by timestamp when the event happened to avoid
 136          * coalescing and thus dropping events.
 137          */
 138
 139         qsort(changes, num_changes,
 140               sizeof(*changes), compare_notify_change_events);
 141
 142         for (i=0; i<num_changes; i++) {
 143                 enum ndr_err_code ndr_err;
 144                 struct notify_change_event *c;
 145                 struct FILE_NOTIFY_INFORMATION m;
 146                 DATA_BLOB blob;
 147                 uint16_t pad = 0;
 148
 149                 /* Coalesce any identical records. */
 150                 while (i+1 < num_changes &&
 151                         notify_change_record_identical(&changes[i],
 152                                                 &changes[i+1])) {
 153                         i++;
 154                 }
 155
 156                 c = &changes[i];
 157
 158                 m.FileName1 = c->name;
 159                 m.FileNameLength = strlen_m(c->name)*2;
 160                 m.Action = c->action;
 161
 162                 m._pad = data_blob_null;
 163
 164                 /*
 165                  * Offset to next entry, only if there is one
 166                  */
 167
 168                 if (i == (num_changes-1)) {
 169                         m.NextEntryOffset = 0;
 170                 } else {
 171                         if ((m.FileNameLength % 4) == 2) {
 172                                 m._pad = data_blob_const(&pad, 2);
 173                         }
 174                         m.NextEntryOffset =
 175                                 ndr_size_FILE_NOTIFY_INFORMATION(&m, 0);
 176                 }
 177
 178                 ndr_err = ndr_push_struct_blob(&blob, talloc_tos(), &m,
 179                         (ndr_push_flags_fn_t)ndr_push_FILE_NOTIFY_INFORMATION);
 180                 if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 181                         return false;
 182                 }
 183
 184                 if (DEBUGLEVEL >= 10) {
 185                         NDR_PRINT_DEBUG(FILE_NOTIFY_INFORMATION, &m);
 186                 }
 187
 188                 if (!data_blob_append(talloc_tos(), final_blob,
 189                                       blob.data, blob.length)) {
 190                         data_blob_free(&blob);
 191                         return false;
 192                 }
 193
 194                 data_blob_free(&blob);
 195
 196                 if (final_blob->length > max_offset) {
 197                         /* Too much data for client. */
 198                         DEBUG(10, ("Client only wanted %d bytes, trying to "
 199                                    "marshall %d bytes\n", (int)max_offset,
 200                                    (int)final_blob->length));
 201                         return False;
 202                 }
 203         }
 204
 205         return True;
 206 }
 207
 208 /****************************************************************************
 209  Setup the common parts of the return packet and send it.
 210 *****************************************************************************/
 211
 212 void change_notify_reply(struct smb_request *req,
 213                          NTSTATUS error_code,
 214                          uint32_t max_param,
 215                          struct notify_change_buf *notify_buf,
 216                          void (*reply_fn)(struct smb_request *req,
 217                                           NTSTATUS error_code,
 218                                           uint8_t *buf, size_t len))
 219 {
 220         DATA_BLOB blob = data_blob_null;
 221
 222         if (!NT_STATUS_IS_OK(error_code)) {
 223                 reply_fn(req, error_code, NULL, 0);
 224                 return;
 225         }
 226
 227         if (max_param == 0 || notify_buf == NULL) {
 228                 reply_fn(req, NT_STATUS_OK, NULL, 0);
 229                 return;
 230         }
 231
 232         if (!notify_marshall_changes(notify_buf->num_changes, max_param,
 233                                         notify_buf->changes, &blob)) {
 234                 /*
 235                  * We exceed what the client is willing to accept. Send
 236                  * nothing.
 237                  */
 238                 data_blob_free(&blob);
 239         }
 240
 241         reply_fn(req, NT_STATUS_OK, blob.data, blob.length);
 242
 243         data_blob_free(&blob);
 244
 245         TALLOC_FREE(notify_buf->changes);
 246         notify_buf->num_changes = 0;
 247 }
 248
 249 struct notify_fsp_state {
 250         struct files_struct *notified_fsp;
 251         struct timespec when;
 252         const struct notify_event *e;
 253 };
 254
 255 static struct files_struct *notify_fsp_cb(struct files_struct *fsp,
 256                                           void *private_data)
 257 {
 258         struct notify_fsp_state *state = private_data;
 259
 260         if (fsp == state->notified_fsp) {
 261                 DBG_DEBUG("notify_callback called for %s\n", fsp_str_dbg(fsp));
 262                 notify_fsp(fsp, state->when, state->e->action, state->e->path);
 263                 return fsp;
 264         }
 265
 266         return NULL;
 267 }
 268
 269 void notify_callback(struct smbd_server_connection *sconn,
 270                      void *private_data, struct timespec when,
 271                      const struct notify_event *e)
 272 {
 273         struct notify_fsp_state state = {
 274                 .notified_fsp = private_data, .when = when, .e = e
 275         };
 276         files_forall(sconn, notify_fsp_cb, &state);
 277 }
 278
 279 NTSTATUS change_notify_create(struct files_struct *fsp, uint32_t filter,
 280                               bool recursive)
 281 {
 282         size_t len = fsp_fullbasepath(fsp, NULL, 0);
 283         char fullpath[len+1];
 284         NTSTATUS status = NT_STATUS_NOT_IMPLEMENTED;
 285
 286         if (fsp->notify != NULL) {
 287                 DEBUG(1, ("change_notify_create: fsp->notify != NULL, "
 288                           "fname = %s\n", fsp->fsp_name->base_name));
 289                 return NT_STATUS_INVALID_PARAMETER;
 290         }
 291
 292         if (!(fsp->notify = talloc_zero(NULL, struct notify_change_buf))) {
 293                 DEBUG(0, ("talloc failed\n"));
 294                 return NT_STATUS_NO_MEMORY;
 295         }
 296         fsp->notify->filter = filter;
 297         fsp->notify->subdir_filter = recursive ? filter : 0;
 298
 299         fsp_fullbasepath(fsp, fullpath, sizeof(fullpath));
 300
 301         /*
 302          * Avoid /. at the end of the path name. notify can't deal with it.
 303          */
 304         if (len > 1 && fullpath[len-1] == '.' && fullpath[len-2] == '/') {
 305                 fullpath[len-2] = '\0';
 306         }
 307
 308         if ((fsp->notify->filter != 0) ||
 309             (fsp->notify->subdir_filter != 0)) {
 310                 status = notify_add(fsp->conn->sconn->notify_ctx,
 311                                     fullpath, fsp->notify->filter,
 312                                     fsp->notify->subdir_filter, fsp);
 313         }
 314
 315         return status;
 316 }
 317
 318 NTSTATUS change_notify_add_request(struct smb_request *req,
 319                                 uint32_t max_param,
 320                                 uint32_t filter, bool recursive,
 321                                 struct files_struct *fsp,
 322                                 void (*reply_fn)(struct smb_request *req,
 323                                         NTSTATUS error_code,
 324                                         uint8_t *buf, size_t len))
 325 {
 326         struct notify_change_request *request = NULL;
 327         struct notify_mid_map *map = NULL;
 328         struct smbd_server_connection *sconn = req->sconn;
 329
 330         DEBUG(10, ("change_notify_add_request: Adding request for %s: "
 331                    "max_param = %d\n", fsp_str_dbg(fsp), (int)max_param));
 332
 333         if (!(request = talloc(NULL, struct notify_change_request))
 334             || !(map = talloc(request, struct notify_mid_map))) {
 335                 TALLOC_FREE(request);
 336                 return NT_STATUS_NO_MEMORY;
 337         }
 338
 339         request->mid_map = map;
 340         map->req = request;
 341
 342         request->req = talloc_move(request, &req);
 343         request->max_param = max_param;
 344         request->filter = filter;
 345         request->fsp = fsp;
 346         request->reply_fn = reply_fn;
 347         request->backend_data = NULL;
 348
 349         DLIST_ADD_END(fsp->notify->requests, request);
 350
 351         map->mid = request->req->mid;
 352         DLIST_ADD(sconn->smb1.notify_mid_maps, map);
 353
 354         return NT_STATUS_OK;
 355 }
 356
 357 static void change_notify_remove_request(struct smbd_server_connection *sconn,
 358                                          struct notify_change_request *remove_req)
 359 {
 360         files_struct *fsp;
 361         struct notify_change_request *req;
 362
 363         /*
 364          * Paranoia checks, the fsp referenced must must have the request in
 365          * its list of pending requests
 366          */
 367
 368         fsp = remove_req->fsp;
 369         SMB_ASSERT(fsp->notify != NULL);
 370
 371         for (req = fsp->notify->requests; req; req = req->next) {
 372                 if (req == remove_req) {
 373                         break;
 374                 }
 375         }
 376
 377         if (req == NULL) {
 378                 smb_panic("notify_req not found in fsp's requests");
 379         }
 380
 381         DLIST_REMOVE(fsp->notify->requests, req);
 382         DLIST_REMOVE(sconn->smb1.notify_mid_maps, req->mid_map);
 383         TALLOC_FREE(req);
 384 }
 385
 386 static void smbd_notify_cancel_by_map(struct notify_mid_map *map)
 387 {
 388         struct smb_request *smbreq = map->req->req;
 389         struct smbd_server_connection *sconn = smbreq->sconn;
 390         struct smbd_smb2_request *smb2req = smbreq->smb2req;
 391         NTSTATUS notify_status = NT_STATUS_CANCELLED;
 392
 393         if (smb2req != NULL) {
 394                 if (smb2req->session == NULL) {
 395                         notify_status = STATUS_NOTIFY_CLEANUP;
 396                 } else if (!NT_STATUS_IS_OK(smb2req->session->status)) {
 397                         notify_status = STATUS_NOTIFY_CLEANUP;
 398                 }
 399                 if (smb2req->tcon == NULL) {
 400                         notify_status = STATUS_NOTIFY_CLEANUP;
 401                 } else if (!NT_STATUS_IS_OK(smb2req->tcon->status)) {
 402                         notify_status = STATUS_NOTIFY_CLEANUP;
 403                 }
 404         }
 405
 406         change_notify_reply(smbreq, notify_status,
 407                             0, NULL, map->req->reply_fn);
 408         change_notify_remove_request(sconn, map->req);
 409 }
 410
 411 /****************************************************************************
 412  Delete entries by mid from the change notify pending queue. Always send reply.
 413 *****************************************************************************/
 414
 415 void remove_pending_change_notify_requests_by_mid(
 416         struct smbd_server_connection *sconn, uint64_t mid)
 417 {
 418         struct notify_mid_map *map;
 419
 420         for (map = sconn->smb1.notify_mid_maps; map; map = map->next) {
 421                 if (map->mid == mid) {
 422                         break;
 423                 }
 424         }
 425
 426         if (map == NULL) {
 427                 return;
 428         }
 429
 430         smbd_notify_cancel_by_map(map);
 431 }
 432
 433 void smbd_notify_cancel_by_smbreq(const struct smb_request *smbreq)
 434 {
 435         struct smbd_server_connection *sconn = smbreq->sconn;
 436         struct notify_mid_map *map;
 437
 438         for (map = sconn->smb1.notify_mid_maps; map; map = map->next) {
 439                 if (map->req->req == smbreq) {
 440                         break;
 441                 }
 442         }
 443
 444         if (map == NULL) {
 445                 return;
 446         }
 447
 448         smbd_notify_cancel_by_map(map);
 449 }
 450
 451 static struct files_struct *smbd_notify_cancel_deleted_fn(
 452         struct files_struct *fsp, void *private_data)
 453 {
 454         struct file_id *fid = talloc_get_type_abort(
 455                 private_data, struct file_id);
 456
 457         if (file_id_equal(&fsp->file_id, fid)) {
 458                 remove_pending_change_notify_requests_by_fid(
 459                         fsp, NT_STATUS_DELETE_PENDING);
 460         }
 461         return NULL;
 462 }
 463
 464 void smbd_notify_cancel_deleted(struct messaging_context *msg,
 465                                 void *private_data, uint32_t msg_type,
 466                                 struct server_id server_id, DATA_BLOB *data)
 467 {
 468         struct smbd_server_connection *sconn = talloc_get_type_abort(
 469                 private_data, struct smbd_server_connection);
 470         struct file_id *fid;
 471         enum ndr_err_code ndr_err;
 472
 473         fid = talloc(talloc_tos(), struct file_id);
 474         if (fid == NULL) {
 475                 DEBUG(1, ("talloc failed\n"));
 476                 return;
 477         }
 478
 479         ndr_err = ndr_pull_struct_blob_all(
 480                 data, fid, fid, (ndr_pull_flags_fn_t)ndr_pull_file_id);
 481         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 482                 DEBUG(10, ("%s: ndr_pull_file_id failed: %s\n", __func__,
 483                            ndr_errstr(ndr_err)));
 484                 goto done;
 485         }
 486
 487         files_forall(sconn, smbd_notify_cancel_deleted_fn, fid);
 488
 489 done:
 490         TALLOC_FREE(fid);
 491 }
 492
 493 static struct files_struct *smbd_notifyd_reregister(struct files_struct *fsp,
 494                                                     void *private_data)
 495 {
 496         DBG_DEBUG("reregister %s\n", fsp->fsp_name->base_name);
 497
 498         if ((fsp->conn->sconn->notify_ctx != NULL) &&
 499             (fsp->notify != NULL) &&
 500             ((fsp->notify->filter != 0) ||
 501              (fsp->notify->subdir_filter != 0))) {
 502                 size_t len = fsp_fullbasepath(fsp, NULL, 0);
 503                 char fullpath[len+1];
 504
 505                 NTSTATUS status;
 506
 507                 fsp_fullbasepath(fsp, fullpath, sizeof(fullpath));
 508                 if (len > 1 && fullpath[len-1] == '.' &&
 509                     fullpath[len-2] == '/') {
 510                         fullpath[len-2] = '\0';
 511                 }
 512
 513                 status = notify_add(fsp->conn->sconn->notify_ctx,
 514                                     fullpath, fsp->notify->filter,
 515                                     fsp->notify->subdir_filter, fsp);
 516                 if (!NT_STATUS_IS_OK(status)) {
 517                         DBG_DEBUG("notify_add failed: %s\n",
 518                                   nt_errstr(status));
 519                 }
 520         }
 521         return NULL;
 522 }
 523
 524 void smbd_notifyd_restarted(struct messaging_context *msg,
 525                             void *private_data, uint32_t msg_type,
 526                             struct server_id server_id, DATA_BLOB *data)
 527 {
 528         struct smbd_server_connection *sconn = talloc_get_type_abort(
 529                 private_data, struct smbd_server_connection);
 530
 531         TALLOC_FREE(sconn->notify_ctx);
 532
 533         sconn->notify_ctx = notify_init(sconn, sconn->msg_ctx, sconn->ev_ctx,
 534                                         sconn, notify_callback);
 535         if (sconn->notify_ctx == NULL) {
 536                 DBG_DEBUG("notify_init failed\n");
 537                 return;
 538         }
 539
 540         files_forall(sconn, smbd_notifyd_reregister, sconn->notify_ctx);
 541 }
 542
 543 /****************************************************************************
 544  Delete entries by fnum from the change notify pending queue.
 545 *****************************************************************************/
 546
 547 void remove_pending_change_notify_requests_by_fid(files_struct *fsp,
 548                                                   NTSTATUS status)
 549 {
 550         if (fsp->notify == NULL) {
 551                 return;
 552         }
 553
 554         while (fsp->notify->requests != NULL) {
 555                 change_notify_reply(fsp->notify->requests->req,
 556                                     status, 0, NULL,
 557                                     fsp->notify->requests->reply_fn);
 558                 change_notify_remove_request(fsp->conn->sconn,
 559                                              fsp->notify->requests);
 560         }
 561 }
 562
 563 void notify_fname(connection_struct *conn, uint32_t action, uint32_t filter,
 564                   const char *path)
 565 {
 566         struct notify_context *notify_ctx = conn->sconn->notify_ctx;
 567
 568         if (path[0] == '.' && path[1] == '/') {
 569                 path += 2;
 570         }
 571
 572         notify_trigger(notify_ctx, action, filter, conn->connectpath, path);
 573 }
 574
 575 static void notify_fsp(files_struct *fsp, struct timespec when,
 576                        uint32_t action, const char *name)
 577 {
 578         struct notify_change_event *change, *changes;
 579         char *tmp;
 580
 581         if (fsp->notify == NULL) {
 582                 /*
 583                  * Nobody is waiting, don't queue
 584                  */
 585                 return;
 586         }
 587
 588         /*
 589          * Someone has triggered a notify previously, queue the change for
 590          * later.
 591          */
 592
 593         if ((fsp->notify->num_changes > 1000) || (name == NULL)) {
 594                 /*
 595                  * The real number depends on the client buf, just provide a
 596                  * guard against a DoS here.  If name == NULL the CN backend is
 597                  * alerting us to a problem.  Possibly dropped events.  Clear
 598                  * queued changes and send the catch-all response to the client
 599                  * if a request is pending.
 600                  */
 601                 TALLOC_FREE(fsp->notify->changes);
 602                 fsp->notify->num_changes = -1;
 603                 if (fsp->notify->requests != NULL) {
 604                         change_notify_reply(fsp->notify->requests->req,
 605                                             NT_STATUS_OK,
 606                                             fsp->notify->requests->max_param,
 607                                             fsp->notify,
 608                                             fsp->notify->requests->reply_fn);
 609                         change_notify_remove_request(fsp->conn->sconn,
 610                                                      fsp->notify->requests);
 611                 }
 612                 return;
 613         }
 614
 615         /* If we've exceeded the server side queue or received a NULL name
 616          * from the underlying CN implementation, don't queue up any more
 617          * requests until we can send a catch-all response to the client */
 618         if (fsp->notify->num_changes == -1) {
 619                 return;
 620         }
 621
 622         if (!(changes = talloc_realloc(
 623                       fsp->notify, fsp->notify->changes,
 624                       struct notify_change_event,
 625                       fsp->notify->num_changes+1))) {
 626                 DEBUG(0, ("talloc_realloc failed\n"));
 627                 return;
 628         }
 629
 630         fsp->notify->changes = changes;
 631
 632         change = &(fsp->notify->changes[fsp->notify->num_changes]);
 633
 634         if (!(tmp = talloc_strdup(changes, name))) {
 635                 DEBUG(0, ("talloc_strdup failed\n"));
 636                 return;
 637         }
 638
 639         string_replace(tmp, '/', '\\');
 640         change->name = tmp;
 641
 642         change->when = when;
 643         change->action = action;
 644         fsp->notify->num_changes += 1;
 645
 646         if (fsp->notify->requests == NULL) {
 647                 /*
 648                  * Nobody is waiting, so don't send anything. The ot
 649                  */
 650                 return;
 651         }
 652
 653         if (action == NOTIFY_ACTION_OLD_NAME) {
 654                 /*
 655                  * We have to send the two rename events in one reply. So hold
 656                  * the first part back.
 657                  */
 658                 return;
 659         }
 660
 661         /*
 662          * Someone is waiting for the change, trigger the reply immediately.
 663          *
 664          * TODO: do we have to walk the lists of requests pending?
 665          */
 666
 667         change_notify_reply(fsp->notify->requests->req,
 668                             NT_STATUS_OK,
 669                             fsp->notify->requests->max_param,
 670                             fsp->notify,
 671                             fsp->notify->requests->reply_fn);
 672
 673         change_notify_remove_request(fsp->conn->sconn, fsp->notify->requests);
 674 }
 675
 676 char *notify_filter_string(TALLOC_CTX *mem_ctx, uint32_t filter)
 677 {
 678         char *result = NULL;
 679
 680         result = talloc_strdup(mem_ctx, "");
 681
 682         if (filter & FILE_NOTIFY_CHANGE_FILE_NAME)
 683                 result = talloc_asprintf_append(result, "FILE_NAME|");
 684         if (filter & FILE_NOTIFY_CHANGE_DIR_NAME)
 685                 result = talloc_asprintf_append(result, "DIR_NAME|");
 686         if (filter & FILE_NOTIFY_CHANGE_ATTRIBUTES)
 687                 result = talloc_asprintf_append(result, "ATTRIBUTES|");
 688         if (filter & FILE_NOTIFY_CHANGE_SIZE)
 689                 result = talloc_asprintf_append(result, "SIZE|");
 690         if (filter & FILE_NOTIFY_CHANGE_LAST_WRITE)
 691                 result = talloc_asprintf_append(result, "LAST_WRITE|");
 692         if (filter & FILE_NOTIFY_CHANGE_LAST_ACCESS)
 693                 result = talloc_asprintf_append(result, "LAST_ACCESS|");
 694         if (filter & FILE_NOTIFY_CHANGE_CREATION)
 695                 result = talloc_asprintf_append(result, "CREATION|");
 696         if (filter & FILE_NOTIFY_CHANGE_EA)
 697                 result = talloc_asprintf_append(result, "EA|");
 698         if (filter & FILE_NOTIFY_CHANGE_SECURITY)
 699                 result = talloc_asprintf_append(result, "SECURITY|");
 700         if (filter & FILE_NOTIFY_CHANGE_STREAM_NAME)
 701                 result = talloc_asprintf_append(result, "STREAM_NAME|");
 702         if (filter & FILE_NOTIFY_CHANGE_STREAM_SIZE)
 703                 result = talloc_asprintf_append(result, "STREAM_SIZE|");
 704         if (filter & FILE_NOTIFY_CHANGE_STREAM_WRITE)
 705                 result = talloc_asprintf_append(result, "STREAM_WRITE|");
 706
 707         if (result == NULL) return NULL;
 708         if (*result == '\0') return result;
 709
 710         result[strlen(result)-1] = '\0';
 711         return result;
 712 }
 713
 714 struct sys_notify_context *sys_notify_context_create(TALLOC_CTX *mem_ctx,
 715                                                      struct tevent_context *ev)
 716 {
 717         struct sys_notify_context *ctx;
 718
 719         if (!(ctx = talloc(mem_ctx, struct sys_notify_context))) {
 720                 DEBUG(0, ("talloc failed\n"));
 721                 return NULL;
 722         }
 723
 724         ctx->ev = ev;
 725         ctx->private_data = NULL;
 726         return ctx;
 727 }