source/smbd/notify_internal.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3
   4    Copyright (C) Andrew Tridgell 2006
   5
   6    This program is free software; you can redistribute it and/or modify
   7    it under the terms of the GNU General Public License as published by
   8    the Free Software Foundation; either version 2 of the License, or
   9    (at your option) any later version.
  10
  11    This program is distributed in the hope that it will be useful,
  12    but WITHOUT ANY WARRANTY; without even the implied warranty of
  13    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  14    GNU General Public License for more details.
  15
  16    You should have received a copy of the GNU General Public License
  17    along with this program; if not, write to the Free Software
  18    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19 */
  20
  21 /*
  22   this is the change notify database. It implements mechanisms for
  23   storing current change notify waiters in a tdb, and checking if a
  24   given event matches any of the stored notify waiiters.
  25 */
  26
  27 #include "includes.h"
  28 #include "librpc/gen_ndr/ndr_notify.h"
  29
  30 struct notify_context {
  31         struct tdb_wrap *w;
  32         struct server_id server;
  33         struct messaging_context *messaging_ctx;
  34         struct notify_list *list;
  35         struct notify_array *array;
  36         int seqnum;
  37         struct sys_notify_context *sys_notify_ctx;
  38 };
  39
  40
  41 struct notify_list {
  42         struct notify_list *next, *prev;
  43         void *private_data;
  44         void (*callback)(void *, const struct notify_event *);
  45         void *sys_notify_handle;
  46         int depth;
  47 };
  48
  49 #define NOTIFY_KEY "notify array"
  50
  51 #define NOTIFY_ENABLE           "notify:enable"
  52 #define NOTIFY_ENABLE_DEFAULT   True
  53
  54 static NTSTATUS notify_remove_all(struct notify_context *notify,
  55                                   const struct server_id *server);
  56 static void notify_handler(struct messaging_context *msg_ctx, void *private_data,
  57                            uint32_t msg_type, struct server_id server_id, DATA_BLOB *data);
  58
  59 /*
  60   destroy the notify context
  61 */
  62 static int notify_destructor(struct notify_context *notify)
  63 {
  64         messaging_deregister(notify->messaging_ctx, MSG_PVFS_NOTIFY, notify);
  65
  66         if (notify->list != NULL) {
  67                 notify_remove_all(notify, &notify->server);
  68         }
  69
  70         return 0;
  71 }
  72
  73 /*
  74   Open up the notify.tdb database. You should close it down using
  75   talloc_free(). We need the messaging_ctx to allow for notifications
  76   via internal messages
  77 */
  78 struct notify_context *notify_init(TALLOC_CTX *mem_ctx, struct server_id server,
  79                                    struct messaging_context *messaging_ctx,
  80                                    struct event_context *ev,
  81                                    connection_struct *conn)
  82 {
  83         struct notify_context *notify;
  84
  85         if (!lp_change_notify(conn->params)) {
  86                 return NULL;
  87         }
  88
  89         notify = talloc(mem_ctx, struct notify_context);
  90         if (notify == NULL) {
  91                 return NULL;
  92         }
  93
  94         notify->w = tdb_wrap_open(notify, lock_path("notify.tdb"),
  95                                   0, TDB_SEQNUM|TDB_CLEAR_IF_FIRST,
  96                                   O_RDWR|O_CREAT, 0644);
  97         if (notify->w == NULL) {
  98                 talloc_free(notify);
  99                 return NULL;
 100         }
 101
 102         notify->server = server;
 103         notify->messaging_ctx = messaging_ctx;
 104         notify->list = NULL;
 105         notify->array = NULL;
 106         notify->seqnum = tdb_get_seqnum(notify->w->tdb);
 107
 108         talloc_set_destructor(notify, notify_destructor);
 109
 110         /* register with the messaging subsystem for the notify
 111            message type */
 112         messaging_register(notify->messaging_ctx, notify,
 113                            MSG_PVFS_NOTIFY, notify_handler);
 114
 115         notify->sys_notify_ctx = sys_notify_context_create(conn, notify, ev);
 116
 117         return notify;
 118 }
 119
 120
 121 /*
 122   lock the notify db
 123 */
 124 static NTSTATUS notify_lock(struct notify_context *notify)
 125 {
 126         if (tdb_lock_bystring(notify->w->tdb, NOTIFY_KEY) != 0) {
 127                 return NT_STATUS_INTERNAL_DB_CORRUPTION;
 128         }
 129         return NT_STATUS_OK;
 130 }
 131
 132 /*
 133   unlock the notify db
 134 */
 135 static void notify_unlock(struct notify_context *notify)
 136 {
 137         tdb_unlock_bystring(notify->w->tdb, NOTIFY_KEY);
 138 }
 139
 140 /*
 141   load the notify array
 142 */
 143 static NTSTATUS notify_load(struct notify_context *notify)
 144 {
 145         TDB_DATA dbuf;
 146         DATA_BLOB blob;
 147         NTSTATUS status;
 148         int seqnum;
 149
 150         seqnum = tdb_get_seqnum(notify->w->tdb);
 151
 152         if (seqnum == notify->seqnum && notify->array != NULL) {
 153                 return NT_STATUS_OK;
 154         }
 155
 156         notify->seqnum = seqnum;
 157
 158         talloc_free(notify->array);
 159         notify->array = TALLOC_ZERO_P(notify, struct notify_array);
 160         NT_STATUS_HAVE_NO_MEMORY(notify->array);
 161
 162         dbuf = tdb_fetch_bystring(notify->w->tdb, NOTIFY_KEY);
 163         if (dbuf.dptr == NULL) {
 164                 return NT_STATUS_OK;
 165         }
 166
 167         blob.data = (uint8 *)dbuf.dptr;
 168         blob.length = dbuf.dsize;
 169
 170         status = ndr_pull_struct_blob(&blob, notify->array, notify->array,
 171                                       (ndr_pull_flags_fn_t)ndr_pull_notify_array);
 172
 173         if (DEBUGLEVEL >= 10) {
 174                 DEBUG(10, ("notify_load:\n"));
 175                 NDR_PRINT_DEBUG(notify_array, notify->array);
 176         }
 177
 178         free(dbuf.dptr);
 179
 180         return status;
 181 }
 182
 183 /*
 184   compare notify entries for sorting
 185 */
 186 static int notify_compare(const void *p1, const void *p2)
 187 {
 188         const struct notify_entry *e1 = (const struct notify_entry *)p1;
 189         const struct notify_entry *e2 = (const struct notify_entry *)p2;
 190         return strcmp(e1->path, e2->path);
 191 }
 192
 193 /*
 194   save the notify array
 195 */
 196 static NTSTATUS notify_save(struct notify_context *notify)
 197 {
 198         TDB_DATA dbuf;
 199         DATA_BLOB blob;
 200         NTSTATUS status;
 201         int ret;
 202         TALLOC_CTX *tmp_ctx;
 203
 204         /* if possible, remove some depth arrays */
 205         while (notify->array->num_depths > 0 &&
 206                notify->array->depth[notify->array->num_depths-1].num_entries == 0) {
 207                 notify->array->num_depths--;
 208         }
 209
 210         /* we might just be able to delete the record */
 211         if (notify->array->num_depths == 0) {
 212                 ret = tdb_delete_bystring(notify->w->tdb, NOTIFY_KEY);
 213                 if (ret != 0) {
 214                         return NT_STATUS_INTERNAL_DB_CORRUPTION;
 215                 }
 216                 return NT_STATUS_OK;
 217         }
 218
 219         tmp_ctx = talloc_new(notify);
 220         NT_STATUS_HAVE_NO_MEMORY(tmp_ctx);
 221
 222         status = ndr_push_struct_blob(&blob, tmp_ctx, notify->array,
 223                                       (ndr_push_flags_fn_t)ndr_push_notify_array);
 224         if (!NT_STATUS_IS_OK(status)) {
 225                 talloc_free(tmp_ctx);
 226                 return status;
 227         }
 228
 229         if (DEBUGLEVEL >= 10) {
 230                 DEBUG(10, ("notify_save:\n"));
 231                 NDR_PRINT_DEBUG(notify_array, notify->array);
 232         }
 233
 234         dbuf.dptr = (char *)blob.data;
 235         dbuf.dsize = blob.length;
 236
 237         ret = tdb_store_bystring(notify->w->tdb, NOTIFY_KEY, dbuf, TDB_REPLACE);
 238         talloc_free(tmp_ctx);
 239         if (ret != 0) {
 240                 return NT_STATUS_INTERNAL_DB_CORRUPTION;
 241         }
 242
 243         return NT_STATUS_OK;
 244 }
 245
 246
 247 /*
 248   handle incoming notify messages
 249 */
 250 static void notify_handler(struct messaging_context *msg_ctx, void *private_data,
 251                            uint32_t msg_type, struct server_id server_id, DATA_BLOB *data)
 252 {
 253         struct notify_context *notify = talloc_get_type(private_data, struct notify_context);
 254         NTSTATUS status;
 255         struct notify_event ev;
 256         TALLOC_CTX *tmp_ctx = talloc_new(notify);
 257         struct notify_list *listel;
 258
 259         if (tmp_ctx == NULL) {
 260                 return;
 261         }
 262
 263         status = ndr_pull_struct_blob(data, tmp_ctx, &ev,
 264                                       (ndr_pull_flags_fn_t)ndr_pull_notify_event);
 265         if (!NT_STATUS_IS_OK(status)) {
 266                 talloc_free(tmp_ctx);
 267                 return;
 268         }
 269
 270         for (listel=notify->list;listel;listel=listel->next) {
 271                 if (listel->private_data == ev.private_data) {
 272                         listel->callback(listel->private_data, &ev);
 273                         break;
 274                 }
 275         }
 276
 277         talloc_free(tmp_ctx);
 278 }
 279
 280 /*
 281   callback from sys_notify telling us about changes from the OS
 282 */
 283 static void sys_notify_callback(struct sys_notify_context *ctx,
 284                                 void *ptr, struct notify_event *ev)
 285 {
 286         struct notify_list *listel = talloc_get_type(ptr, struct notify_list);
 287         ev->private_data = listel;
 288         DEBUG(10, ("sys_notify_callback called with action=%d, for %s\n",
 289                    ev->action, ev->path));
 290         listel->callback(listel->private_data, ev);
 291 }
 292
 293 /*
 294   add an entry to the notify array
 295 */
 296 static NTSTATUS notify_add_array(struct notify_context *notify, struct notify_entry *e,
 297                                  void *private_data, int depth)
 298 {
 299         int i;
 300         struct notify_depth *d;
 301         struct notify_entry *ee;
 302
 303         /* possibly expand the depths array */
 304         if (depth >= notify->array->num_depths) {
 305                 d = talloc_realloc(notify->array, notify->array->depth,
 306                                    struct notify_depth, depth+1);
 307                 NT_STATUS_HAVE_NO_MEMORY(d);
 308                 for (i=notify->array->num_depths;i<=depth;i++) {
 309                         ZERO_STRUCT(d[i]);
 310                 }
 311                 notify->array->depth = d;
 312                 notify->array->num_depths = depth+1;
 313         }
 314         d = &notify->array->depth[depth];
 315
 316         /* expand the entries array */
 317         ee = talloc_realloc(notify->array->depth, d->entries, struct notify_entry,
 318                             d->num_entries+1);
 319         NT_STATUS_HAVE_NO_MEMORY(ee);
 320         d->entries = ee;
 321
 322         d->entries[d->num_entries] = *e;
 323         d->entries[d->num_entries].private_data = private_data;
 324         d->entries[d->num_entries].server = notify->server;
 325         d->entries[d->num_entries].path_len = strlen(e->path);
 326         d->num_entries++;
 327
 328         d->max_mask |= e->filter;
 329         d->max_mask_subdir |= e->subdir_filter;
 330
 331         if (d->num_entries > 1) {
 332                 qsort(d->entries, d->num_entries, sizeof(d->entries[0]), notify_compare);
 333         }
 334
 335         /* recalculate the maximum masks */
 336         d->max_mask = 0;
 337         d->max_mask_subdir = 0;
 338
 339         for (i=0;i<d->num_entries;i++) {
 340                 d->max_mask |= d->entries[i].filter;
 341                 d->max_mask_subdir |= d->entries[i].subdir_filter;
 342         }
 343
 344         return notify_save(notify);
 345 }
 346
 347 /*
 348   add a notify watch. This is called when a notify is first setup on a open
 349   directory handle.
 350 */
 351 NTSTATUS notify_add(struct notify_context *notify, struct notify_entry *e0,
 352                     void (*callback)(void *, const struct notify_event *),
 353                     void *private_data)
 354 {
 355         struct notify_entry e = *e0;
 356         NTSTATUS status;
 357         char *tmp_path = NULL;
 358         struct notify_list *listel;
 359         size_t len;
 360         int depth;
 361
 362         /* see if change notify is enabled at all */
 363         if (notify == NULL) {
 364                 return NT_STATUS_NOT_IMPLEMENTED;
 365         }
 366
 367         status = notify_lock(notify);
 368         NT_STATUS_NOT_OK_RETURN(status);
 369
 370         status = notify_load(notify);
 371         if (!NT_STATUS_IS_OK(status)) {
 372                 goto done;
 373         }
 374
 375         /* cope with /. on the end of the path */
 376         len = strlen(e.path);
 377         if (len > 1 && e.path[len-1] == '.' && e.path[len-2] == '/') {
 378                 tmp_path = talloc_strndup(notify, e.path, len-2);
 379                 if (tmp_path == NULL) {
 380                         status = NT_STATUS_NO_MEMORY;
 381                         goto done;
 382                 }
 383                 e.path = tmp_path;
 384         }
 385
 386         depth = count_chars(e.path, '/');
 387
 388         listel = TALLOC_ZERO_P(notify, struct notify_list);
 389         if (listel == NULL) {
 390                 status = NT_STATUS_NO_MEMORY;
 391                 goto done;
 392         }
 393
 394         listel->private_data = private_data;
 395         listel->callback = callback;
 396         listel->depth = depth;
 397         DLIST_ADD(notify->list, listel);
 398
 399         /* ignore failures from sys_notify */
 400         if (notify->sys_notify_ctx != NULL) {
 401                 /*
 402                   this call will modify e.filter and e.subdir_filter
 403                   to remove bits handled by the backend
 404                 */
 405                 status = sys_notify_watch(notify->sys_notify_ctx, &e,
 406                                           sys_notify_callback, listel,
 407                                           &listel->sys_notify_handle);
 408                 if (NT_STATUS_IS_OK(status)) {
 409                         talloc_steal(listel, listel->sys_notify_handle);
 410                 }
 411         }
 412
 413         /* if the system notify handler couldn't handle some of the
 414            filter bits, or couldn't handle a request for recursion
 415            then we need to install it in the array used for the
 416            intra-samba notify handling */
 417         if (e.filter != 0 || e.subdir_filter != 0) {
 418                 status = notify_add_array(notify, &e, private_data, depth);
 419         }
 420
 421 done:
 422         notify_unlock(notify);
 423         talloc_free(tmp_path);
 424
 425         return status;
 426 }
 427
 428 /*
 429   remove a notify watch. Called when the directory handle is closed
 430 */
 431 NTSTATUS notify_remove(struct notify_context *notify, void *private_data)
 432 {
 433         NTSTATUS status;
 434         struct notify_list *listel;
 435         int i, depth;
 436         struct notify_depth *d;
 437
 438         /* see if change notify is enabled at all */
 439         if (notify == NULL) {
 440                 return NT_STATUS_NOT_IMPLEMENTED;
 441         }
 442
 443         for (listel=notify->list;listel;listel=listel->next) {
 444                 if (listel->private_data == private_data) {
 445                         DLIST_REMOVE(notify->list, listel);
 446                         break;
 447                 }
 448         }
 449         if (listel == NULL) {
 450                 return NT_STATUS_OBJECT_NAME_NOT_FOUND;
 451         }
 452
 453         depth = listel->depth;
 454
 455         talloc_free(listel);
 456
 457         status = notify_lock(notify);
 458         NT_STATUS_NOT_OK_RETURN(status);
 459
 460         status = notify_load(notify);
 461         if (!NT_STATUS_IS_OK(status)) {
 462                 notify_unlock(notify);
 463                 return status;
 464         }
 465
 466         if (depth >= notify->array->num_depths) {
 467                 notify_unlock(notify);
 468                 return NT_STATUS_OBJECT_NAME_NOT_FOUND;
 469         }
 470
 471         /* we only have to search at the depth of this element */
 472         d = &notify->array->depth[depth];
 473
 474         for (i=0;i<d->num_entries;i++) {
 475                 if (private_data == d->entries[i].private_data &&
 476                     cluster_id_equal(&notify->server, &d->entries[i].server)) {
 477                         break;
 478                 }
 479         }
 480         if (i == d->num_entries) {
 481                 notify_unlock(notify);
 482                 return NT_STATUS_OBJECT_NAME_NOT_FOUND;
 483         }
 484
 485         if (i < d->num_entries-1) {
 486                 memmove(&d->entries[i], &d->entries[i+1],
 487                         sizeof(d->entries[i])*(d->num_entries-(i+1)));
 488         }
 489         d->num_entries--;
 490
 491         status = notify_save(notify);
 492
 493         notify_unlock(notify);
 494
 495         return status;
 496 }
 497
 498 /*
 499   remove all notify watches for a messaging server
 500 */
 501 static NTSTATUS notify_remove_all(struct notify_context *notify,
 502                                   const struct server_id *server)
 503 {
 504         NTSTATUS status;
 505         int i, depth, del_count=0;
 506
 507         status = notify_lock(notify);
 508         NT_STATUS_NOT_OK_RETURN(status);
 509
 510         status = notify_load(notify);
 511         if (!NT_STATUS_IS_OK(status)) {
 512                 notify_unlock(notify);
 513                 return status;
 514         }
 515
 516         /* we have to search for all entries across all depths, looking for matches
 517            for the server id */
 518         for (depth=0;depth<notify->array->num_depths;depth++) {
 519                 struct notify_depth *d = &notify->array->depth[depth];
 520                 for (i=0;i<d->num_entries;i++) {
 521                         if (cluster_id_equal(server, &d->entries[i].server)) {
 522                                 if (i < d->num_entries-1) {
 523                                         memmove(&d->entries[i], &d->entries[i+1],
 524                                                 sizeof(d->entries[i])*(d->num_entries-(i+1)));
 525                                 }
 526                                 i--;
 527                                 d->num_entries--;
 528                                 del_count++;
 529                         }
 530                 }
 531         }
 532
 533         if (del_count > 0) {
 534                 status = notify_save(notify);
 535         }
 536
 537         notify_unlock(notify);
 538
 539         return status;
 540 }
 541
 542
 543 /*
 544   send a notify message to another messaging server
 545 */
 546 static NTSTATUS notify_send(struct notify_context *notify, struct notify_entry *e,
 547                             const char *path, uint32_t action)
 548 {
 549         struct notify_event ev;
 550         DATA_BLOB data;
 551         NTSTATUS status;
 552         TALLOC_CTX *tmp_ctx;
 553
 554         ev.action = action;
 555         ev.path = path;
 556         ev.private_data = e->private_data;
 557
 558         tmp_ctx = talloc_new(notify);
 559
 560         status = ndr_push_struct_blob(&data, tmp_ctx, &ev,
 561                                       (ndr_push_flags_fn_t)ndr_push_notify_event);
 562         if (!NT_STATUS_IS_OK(status)) {
 563                 talloc_free(tmp_ctx);
 564                 return status;
 565         }
 566
 567         status = messaging_send(notify->messaging_ctx, e->server,
 568                                 MSG_PVFS_NOTIFY, &data);
 569         talloc_free(tmp_ctx);
 570         return status;
 571 }
 572
 573
 574 /*
 575   trigger a notify message for anyone waiting on a matching event
 576
 577   This function is called a lot, and needs to be very fast. The unusual data structure
 578   and traversal is designed to be fast in the average case, even for large numbers of
 579   notifies
 580 */
 581 void notify_trigger(struct notify_context *notify,
 582                     uint32_t action, uint32_t filter, const char *path)
 583 {
 584         NTSTATUS status;
 585         int depth;
 586         const char *p, *next_p;
 587
 588         DEBUG(10, ("notify_trigger called action=0x%x, filter=0x%x, "
 589                    "path=%s\n", (unsigned)action, (unsigned)filter, path));
 590
 591         /* see if change notify is enabled at all */
 592         if (notify == NULL) {
 593                 return;
 594         }
 595
 596  again:
 597         status = notify_load(notify);
 598         if (!NT_STATUS_IS_OK(status)) {
 599                 return;
 600         }
 601
 602         /* loop along the given path, working with each directory depth separately */
 603         for (depth=0,p=path;
 604              p && depth < notify->array->num_depths;
 605              p=next_p,depth++) {
 606                 int p_len = p - path;
 607                 int min_i, max_i, i;
 608                 struct notify_depth *d = &notify->array->depth[depth];
 609                 next_p = strchr(p+1, '/');
 610
 611                 /* see if there are any entries at this depth */
 612                 if (d->num_entries == 0) continue;
 613
 614                 /* try to skip based on the maximum mask. If next_p is
 615                  NULL then we know it will be a 'this directory'
 616                  match, otherwise it must be a subdir match */
 617                 if (next_p != NULL) {
 618                         if (0 == (filter & d->max_mask_subdir)) {
 619                                 continue;
 620                         }
 621                 } else {
 622                         if (0 == (filter & d->max_mask)) {
 623                                 continue;
 624                         }
 625                 }
 626
 627                 /* we know there is an entry here worth looking
 628                  for. Use a bisection search to find the first entry
 629                  with a matching path */
 630                 min_i = 0;
 631                 max_i = d->num_entries-1;
 632
 633                 while (min_i < max_i) {
 634                         struct notify_entry *e;
 635                         int cmp;
 636                         i = (min_i+max_i)/2;
 637                         e = &d->entries[i];
 638                         cmp = strncmp(path, e->path, p_len);
 639                         if (cmp == 0) {
 640                                 if (p_len == e->path_len) {
 641                                         max_i = i;
 642                                 } else {
 643                                         max_i = i-1;
 644                                 }
 645                         } else if (cmp < 0) {
 646                                 max_i = i-1;
 647                         } else {
 648                                 min_i = i+1;
 649                         }
 650                 }
 651
 652                 if (min_i != max_i) {
 653                         /* none match */
 654                         continue;
 655                 }
 656
 657                 /* we now know that the entries start at min_i */
 658                 for (i=min_i;i<d->num_entries;i++) {
 659                         struct notify_entry *e = &d->entries[i];
 660                         if (p_len != e->path_len ||
 661                             strncmp(path, e->path, p_len) != 0) break;
 662                         if (next_p != NULL) {
 663                                 if (0 == (filter & e->subdir_filter)) {
 664                                         continue;
 665                                 }
 666                         } else {
 667                                 if (0 == (filter & e->filter)) {
 668                                         continue;
 669                                 }
 670                         }
 671                         status = notify_send(notify, e, path + e->path_len + 1,
 672                                              action);
 673
 674                         if (NT_STATUS_EQUAL(
 675                                     status, NT_STATUS_INVALID_HANDLE)) {
 676                                 struct server_id server = e->server;
 677
 678                                 DEBUG(10, ("Deleting notify entries for "
 679                                            "process %s because it's gone\n",
 680                                            procid_str_static(&e->server.id)));
 681                                 notify_remove_all(notify, &server);
 682                                 goto again;
 683                         }
 684                 }
 685         }
 686 }