source4/ntvfs/common/notify.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 3 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, see <http://www.gnu.org/licenses/>.
  18 */
  19
  20 /*
  21   this is the change notify database. It implements mechanisms for
  22   storing current change notify waiters in a tdb, and checking if a
  23   given event matches any of the stored notify waiiters.
  24 */
  25
  26 #include "includes.h"
  27 #include "system/filesys.h"
  28 #include "../lib/tdb_compat/tdb_compat.h"
  29 #include "../lib/util/util_tdb.h"
  30 #include "messaging/messaging.h"
  31 #include "lib/tdb_wrap/tdb_wrap.h"
  32 #include "lib/messaging/irpc.h"
  33 #include "librpc/gen_ndr/ndr_notify.h"
  34 #include "../lib/util/dlinklist.h"
  35 #include "ntvfs/common/ntvfs_common.h"
  36 #include "ntvfs/sysdep/sys_notify.h"
  37 #include "cluster/cluster.h"
  38 #include "param/param.h"
  39 #include "lib/util/tsort.h"
  40
  41 struct notify_context {
  42         struct tdb_wrap *w;
  43         struct server_id server;
  44         struct imessaging_context *imessaging_ctx;
  45         struct notify_list *list;
  46         struct notify_array *array;
  47         int seqnum;
  48         struct sys_notify_context *sys_notify_ctx;
  49 };
  50
  51
  52 struct notify_list {
  53         struct notify_list *next, *prev;
  54         void *private_data;
  55         void (*callback)(void *, const struct notify_event *);
  56         void *sys_notify_handle;
  57         int depth;
  58 };
  59
  60 #define NOTIFY_KEY "notify array"
  61
  62 #define NOTIFY_ENABLE           "notify:enable"
  63 #define NOTIFY_ENABLE_DEFAULT   true
  64
  65 static NTSTATUS notify_remove_all(struct notify_context *notify);
  66 static void notify_handler(struct imessaging_context *msg_ctx, void *private_data,
  67                            uint32_t msg_type, struct server_id server_id, DATA_BLOB *data);
  68
  69 /*
  70   destroy the notify context
  71 */
  72 static int notify_destructor(struct notify_context *notify)
  73 {
  74         imessaging_deregister(notify->imessaging_ctx, MSG_PVFS_NOTIFY, notify);
  75         notify_remove_all(notify);
  76         return 0;
  77 }
  78
  79 /*
  80   Open up the notify.tdb database. You should close it down using
  81   talloc_free(). We need the imessaging_ctx to allow for notifications
  82   via internal messages
  83 */
  84 struct notify_context *notify_init(TALLOC_CTX *mem_ctx, struct server_id server,
  85                                    struct imessaging_context *imessaging_ctx,
  86                                    struct loadparm_context *lp_ctx,
  87                                    struct tevent_context *ev,
  88                                    struct share_config *scfg)
  89 {
  90         struct notify_context *notify;
  91
  92         if (share_bool_option(scfg, NOTIFY_ENABLE, NOTIFY_ENABLE_DEFAULT) != true) {
  93                 return NULL;
  94         }
  95
  96         if (ev == NULL) {
  97                 return NULL;
  98         }
  99
 100         notify = talloc(mem_ctx, struct notify_context);
 101         if (notify == NULL) {
 102                 return NULL;
 103         }
 104
 105         notify->w = cluster_tdb_tmp_open(notify, lp_ctx, "notify.tdb", TDB_SEQNUM);
 106         if (notify->w == NULL) {
 107                 talloc_free(notify);
 108                 return NULL;
 109         }
 110
 111         notify->server = server;
 112         notify->imessaging_ctx = imessaging_ctx;
 113         notify->list = NULL;
 114         notify->array = NULL;
 115         notify->seqnum = tdb_get_seqnum(notify->w->tdb);
 116
 117         talloc_set_destructor(notify, notify_destructor);
 118
 119         /* register with the messaging subsystem for the notify
 120            message type */
 121         imessaging_register(notify->imessaging_ctx, notify,
 122                            MSG_PVFS_NOTIFY, notify_handler);
 123
 124         notify->sys_notify_ctx = sys_notify_context_create(scfg, notify, ev);
 125
 126         return notify;
 127 }
 128
 129
 130 /*
 131   lock the notify db
 132 */
 133 static NTSTATUS notify_lock(struct notify_context *notify)
 134 {
 135         if (tdb_lock_bystring(notify->w->tdb, NOTIFY_KEY) != 0) {
 136                 return NT_STATUS_INTERNAL_DB_CORRUPTION;
 137         }
 138         return NT_STATUS_OK;
 139 }
 140
 141 /*
 142   unlock the notify db
 143 */
 144 static void notify_unlock(struct notify_context *notify)
 145 {
 146         tdb_unlock_bystring(notify->w->tdb, NOTIFY_KEY);
 147 }
 148
 149 /*
 150   load the notify array
 151 */
 152 static NTSTATUS notify_load(struct notify_context *notify)
 153 {
 154         TDB_DATA dbuf;
 155         DATA_BLOB blob;
 156         enum ndr_err_code ndr_err;
 157         int seqnum;
 158
 159         seqnum = tdb_get_seqnum(notify->w->tdb);
 160
 161         if (seqnum == notify->seqnum && notify->array != NULL) {
 162                 return NT_STATUS_OK;
 163         }
 164
 165         notify->seqnum = seqnum;
 166
 167         talloc_free(notify->array);
 168         notify->array = talloc_zero(notify, struct notify_array);
 169         NT_STATUS_HAVE_NO_MEMORY(notify->array);
 170
 171         dbuf = tdb_fetch_bystring(notify->w->tdb, NOTIFY_KEY);
 172         if (dbuf.dptr == NULL) {
 173                 return NT_STATUS_OK;
 174         }
 175
 176         blob.data = dbuf.dptr;
 177         blob.length = dbuf.dsize;
 178
 179         ndr_err = ndr_pull_struct_blob(&blob, notify->array, notify->array,
 180                                        (ndr_pull_flags_fn_t)ndr_pull_notify_array);
 181         free(dbuf.dptr);
 182         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 183                 return ndr_map_error2ntstatus(ndr_err);
 184         }
 185
 186         return NT_STATUS_OK;
 187 }
 188
 189 /*
 190   compare notify entries for sorting
 191 */
 192 static int notify_compare(const void *p1, const void *p2)
 193 {
 194         const struct notify_entry *e1 = p1, *e2 = p2;
 195         return strcmp(e1->path, e2->path);
 196 }
 197
 198 /*
 199   save the notify array
 200 */
 201 static NTSTATUS notify_save(struct notify_context *notify)
 202 {
 203         TDB_DATA dbuf;
 204         DATA_BLOB blob;
 205         enum ndr_err_code ndr_err;
 206         int ret;
 207         TALLOC_CTX *tmp_ctx;
 208
 209         /* if possible, remove some depth arrays */
 210         while (notify->array->num_depths > 0 &&
 211                notify->array->depth[notify->array->num_depths-1].num_entries == 0) {
 212                 notify->array->num_depths--;
 213         }
 214
 215         /* we might just be able to delete the record */
 216         if (notify->array->num_depths == 0) {
 217                 ret = tdb_delete_bystring(notify->w->tdb, NOTIFY_KEY);
 218                 if (ret != 0) {
 219                         return NT_STATUS_INTERNAL_DB_CORRUPTION;
 220                 }
 221                 return NT_STATUS_OK;
 222         }
 223
 224         tmp_ctx = talloc_new(notify);
 225         NT_STATUS_HAVE_NO_MEMORY(tmp_ctx);
 226
 227         ndr_err = ndr_push_struct_blob(&blob, tmp_ctx, notify->array,
 228                                        (ndr_push_flags_fn_t)ndr_push_notify_array);
 229         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 230                 talloc_free(tmp_ctx);
 231                 return ndr_map_error2ntstatus(ndr_err);
 232         }
 233
 234         dbuf.dptr = 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 imessaging_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         enum ndr_err_code ndr_err;
 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         ndr_err = ndr_pull_struct_blob(data, tmp_ctx, &ev,
 264                                       (ndr_pull_flags_fn_t)ndr_pull_notify_event);
 265         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 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         listel->callback(listel->private_data, ev);
 289 }
 290
 291 /*
 292   add an entry to the notify array
 293 */
 294 static NTSTATUS notify_add_array(struct notify_context *notify, struct notify_entry *e,
 295                                  void *private_data, int depth)
 296 {
 297         int i;
 298         struct notify_depth *d;
 299         struct notify_entry *ee;
 300
 301         /* possibly expand the depths array */
 302         if (depth >= notify->array->num_depths) {
 303                 d = talloc_realloc(notify->array, notify->array->depth,
 304                                    struct notify_depth, depth+1);
 305                 NT_STATUS_HAVE_NO_MEMORY(d);
 306                 for (i=notify->array->num_depths;i<=depth;i++) {
 307                         ZERO_STRUCT(d[i]);
 308                 }
 309                 notify->array->depth = d;
 310                 notify->array->num_depths = depth+1;
 311         }
 312         d = &notify->array->depth[depth];
 313
 314         /* expand the entries array */
 315         ee = talloc_realloc(notify->array->depth, d->entries, struct notify_entry,
 316                             d->num_entries+1);
 317         NT_STATUS_HAVE_NO_MEMORY(ee);
 318         d->entries = ee;
 319
 320         d->entries[d->num_entries] = *e;
 321         d->entries[d->num_entries].private_data = private_data;
 322         d->entries[d->num_entries].server = notify->server;
 323         d->entries[d->num_entries].path_len = strlen(e->path);
 324         d->num_entries++;
 325
 326         d->max_mask |= e->filter;
 327         d->max_mask_subdir |= e->subdir_filter;
 328
 329         TYPESAFE_QSORT(d->entries, d->num_entries, notify_compare);
 330
 331         /* recalculate the maximum masks */
 332         d->max_mask = 0;
 333         d->max_mask_subdir = 0;
 334
 335         for (i=0;i<d->num_entries;i++) {
 336                 d->max_mask |= d->entries[i].filter;
 337                 d->max_mask_subdir |= d->entries[i].subdir_filter;
 338         }
 339
 340         return notify_save(notify);
 341 }
 342
 343 /*
 344   add a notify watch. This is called when a notify is first setup on a open
 345   directory handle.
 346 */
 347 NTSTATUS notify_add(struct notify_context *notify, struct notify_entry *e0,
 348                     void (*callback)(void *, const struct notify_event *),
 349                     void *private_data)
 350 {
 351         struct notify_entry e = *e0;
 352         NTSTATUS status;
 353         char *tmp_path = NULL;
 354         struct notify_list *listel;
 355         size_t len;
 356         int depth;
 357
 358         /* see if change notify is enabled at all */
 359         if (notify == NULL) {
 360                 return NT_STATUS_NOT_IMPLEMENTED;
 361         }
 362
 363         status = notify_lock(notify);
 364         NT_STATUS_NOT_OK_RETURN(status);
 365
 366         status = notify_load(notify);
 367         if (!NT_STATUS_IS_OK(status)) {
 368                 goto done;
 369         }
 370
 371         /* cope with /. on the end of the path */
 372         len = strlen(e.path);
 373         if (len > 1 && e.path[len-1] == '.' && e.path[len-2] == '/') {
 374                 tmp_path = talloc_strndup(notify, e.path, len-2);
 375                 if (tmp_path == NULL) {
 376                         status = NT_STATUS_NO_MEMORY;
 377                         goto done;
 378                 }
 379                 e.path = tmp_path;
 380         }
 381
 382         depth = count_chars(e.path, '/');
 383
 384         listel = talloc_zero(notify, struct notify_list);
 385         if (listel == NULL) {
 386                 status = NT_STATUS_NO_MEMORY;
 387                 goto done;
 388         }
 389
 390         listel->private_data = private_data;
 391         listel->callback = callback;
 392         listel->depth = depth;
 393         DLIST_ADD(notify->list, listel);
 394
 395         /* ignore failures from sys_notify */
 396         if (notify->sys_notify_ctx != NULL) {
 397                 /*
 398                   this call will modify e.filter and e.subdir_filter
 399                   to remove bits handled by the backend
 400                 */
 401                 status = sys_notify_watch(notify->sys_notify_ctx, &e,
 402                                           sys_notify_callback, listel,
 403                                           &listel->sys_notify_handle);
 404                 if (NT_STATUS_IS_OK(status)) {
 405                         talloc_steal(listel, listel->sys_notify_handle);
 406                 }
 407         }
 408
 409         /* if the system notify handler couldn't handle some of the
 410            filter bits, or couldn't handle a request for recursion
 411            then we need to install it in the array used for the
 412            intra-samba notify handling */
 413         if (e.filter != 0 || e.subdir_filter != 0) {
 414                 status = notify_add_array(notify, &e, private_data, depth);
 415         }
 416
 417 done:
 418         notify_unlock(notify);
 419         talloc_free(tmp_path);
 420
 421         return status;
 422 }
 423
 424 /*
 425   remove a notify watch. Called when the directory handle is closed
 426 */
 427 NTSTATUS notify_remove(struct notify_context *notify, void *private_data)
 428 {
 429         NTSTATUS status;
 430         struct notify_list *listel;
 431         int i, depth;
 432         struct notify_depth *d;
 433
 434         /* see if change notify is enabled at all */
 435         if (notify == NULL) {
 436                 return NT_STATUS_NOT_IMPLEMENTED;
 437         }
 438
 439         for (listel=notify->list;listel;listel=listel->next) {
 440                 if (listel->private_data == private_data) {
 441                         DLIST_REMOVE(notify->list, listel);
 442                         break;
 443                 }
 444         }
 445         if (listel == NULL) {
 446                 return NT_STATUS_OBJECT_NAME_NOT_FOUND;
 447         }
 448
 449         depth = listel->depth;
 450
 451         talloc_free(listel);
 452
 453         status = notify_lock(notify);
 454         NT_STATUS_NOT_OK_RETURN(status);
 455
 456         status = notify_load(notify);
 457         if (!NT_STATUS_IS_OK(status)) {
 458                 notify_unlock(notify);
 459                 return status;
 460         }
 461
 462         if (depth >= notify->array->num_depths) {
 463                 notify_unlock(notify);
 464                 return NT_STATUS_OBJECT_NAME_NOT_FOUND;
 465         }
 466
 467         /* we only have to search at the depth of this element */
 468         d = &notify->array->depth[depth];
 469
 470         for (i=0;i<d->num_entries;i++) {
 471                 if (private_data == d->entries[i].private_data &&
 472                     cluster_id_equal(&notify->server, &d->entries[i].server)) {
 473                         break;
 474                 }
 475         }
 476         if (i == d->num_entries) {
 477                 notify_unlock(notify);
 478                 return NT_STATUS_OBJECT_NAME_NOT_FOUND;
 479         }
 480
 481         if (i < d->num_entries-1) {
 482                 memmove(&d->entries[i], &d->entries[i+1],
 483                         sizeof(d->entries[i])*(d->num_entries-(i+1)));
 484         }
 485         d->num_entries--;
 486
 487         status = notify_save(notify);
 488
 489         notify_unlock(notify);
 490
 491         return status;
 492 }
 493
 494 /*
 495   remove all notify watches for this messaging server
 496 */
 497 static NTSTATUS notify_remove_all(struct notify_context *notify)
 498 {
 499         NTSTATUS status;
 500         int i, depth, del_count=0;
 501
 502         if (notify->list == NULL) {
 503                 return NT_STATUS_OK;
 504         }
 505
 506         status = notify_lock(notify);
 507         NT_STATUS_NOT_OK_RETURN(status);
 508
 509         status = notify_load(notify);
 510         if (!NT_STATUS_IS_OK(status)) {
 511                 notify_unlock(notify);
 512                 return status;
 513         }
 514
 515         /* we have to search for all entries across all depths, looking for matches
 516            for our server id */
 517         for (depth=0;depth<notify->array->num_depths;depth++) {
 518                 struct notify_depth *d = &notify->array->depth[depth];
 519                 for (i=0;i<d->num_entries;i++) {
 520                         if (cluster_id_equal(&notify->server, &d->entries[i].server)) {
 521                                 if (i < d->num_entries-1) {
 522                                         memmove(&d->entries[i], &d->entries[i+1],
 523                                                 sizeof(d->entries[i])*(d->num_entries-(i+1)));
 524                                 }
 525                                 i--;
 526                                 d->num_entries--;
 527                                 del_count++;
 528                         }
 529                 }
 530         }
 531
 532         if (del_count > 0) {
 533                 status = notify_save(notify);
 534         }
 535
 536         notify_unlock(notify);
 537
 538         return status;
 539 }
 540
 541
 542 /*
 543   send a notify message to another messaging server
 544 */
 545 static void notify_send(struct notify_context *notify, struct notify_entry *e,
 546                         const char *path, uint32_t action)
 547 {
 548         struct notify_event ev;
 549         DATA_BLOB data;
 550         NTSTATUS status;
 551         enum ndr_err_code ndr_err;
 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         ndr_err = ndr_push_struct_blob(&data, tmp_ctx, &ev, (ndr_push_flags_fn_t)ndr_push_notify_event);
 561         if (!NDR_ERR_CODE_IS_SUCCESS(ndr_err)) {
 562                 talloc_free(tmp_ctx);
 563                 return;
 564         }
 565
 566         status = imessaging_send(notify->imessaging_ctx, e->server,
 567                                 MSG_PVFS_NOTIFY, &data);
 568         talloc_free(tmp_ctx);
 569 }
 570
 571
 572 /*
 573   trigger a notify message for anyone waiting on a matching event
 574
 575   This function is called a lot, and needs to be very fast. The unusual data structure
 576   and traversal is designed to be fast in the average case, even for large numbers of
 577   notifies
 578 */
 579 void notify_trigger(struct notify_context *notify,
 580                     uint32_t action, uint32_t filter, const char *path)
 581 {
 582         NTSTATUS status;
 583         int depth;
 584         const char *p, *next_p;
 585
 586         /* see if change notify is enabled at all */
 587         if (notify == NULL) {
 588                 return;
 589         }
 590
 591         status = notify_load(notify);
 592         if (!NT_STATUS_IS_OK(status)) {
 593                 return;
 594         }
 595
 596         /* loop along the given path, working with each directory depth separately */
 597         for (depth=0,p=path;
 598              p && depth < notify->array->num_depths;
 599              p=next_p,depth++) {
 600                 int p_len = p - path;
 601                 int min_i, max_i, i;
 602                 struct notify_depth *d = &notify->array->depth[depth];
 603                 next_p = strchr(p+1, '/');
 604
 605                 /* see if there are any entries at this depth */
 606                 if (d->num_entries == 0) continue;
 607
 608                 /* try to skip based on the maximum mask. If next_p is
 609                  NULL then we know it will be a 'this directory'
 610                  match, otherwise it must be a subdir match */
 611                 if (next_p != NULL) {
 612                         if (0 == (filter & d->max_mask_subdir)) {
 613                                 continue;
 614                         }
 615                 } else {
 616                         if (0 == (filter & d->max_mask)) {
 617                                 continue;
 618                         }
 619                 }
 620
 621                 /* we know there is an entry here worth looking
 622                  for. Use a bisection search to find the first entry
 623                  with a matching path */
 624                 min_i = 0;
 625                 max_i = d->num_entries-1;
 626
 627                 while (min_i < max_i) {
 628                         struct notify_entry *e;
 629                         int cmp;
 630                         i = (min_i+max_i)/2;
 631                         e = &d->entries[i];
 632                         cmp = strncmp(path, e->path, p_len);
 633                         if (cmp == 0) {
 634                                 if (p_len == e->path_len) {
 635                                         max_i = i;
 636                                 } else {
 637                                         max_i = i-1;
 638                                 }
 639                         } else if (cmp < 0) {
 640                                 max_i = i-1;
 641                         } else {
 642                                 min_i = i+1;
 643                         }
 644                 }
 645
 646                 if (min_i != max_i) {
 647                         /* none match */
 648                         continue;
 649                 }
 650
 651                 /* we now know that the entries start at min_i */
 652                 for (i=min_i;i<d->num_entries;i++) {
 653                         struct notify_entry *e = &d->entries[i];
 654                         if (p_len != e->path_len ||
 655                             strncmp(path, e->path, p_len) != 0) break;
 656                         if (next_p != NULL) {
 657                                 if (0 == (filter & e->subdir_filter)) {
 658                                         continue;
 659                                 }
 660                         } else {
 661                                 if (0 == (filter & e->filter)) {
 662                                         continue;
 663                                 }
 664                         }
 665                         notify_send(notify, e, path + e->path_len + 1, action);
 666                 }
 667         }
 668 }