source3/lib/g_lock.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    global locks based on dbwrap and messaging
   4    Copyright (C) 2009 by Volker Lendecke
   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 #include "includes.h"
  21 #include "system/filesys.h"
  22 #include "lib/util/server_id.h"
  23 #include "dbwrap/dbwrap.h"
  24 #include "dbwrap/dbwrap_open.h"
  25 #include "dbwrap/dbwrap_watch.h"
  26 #include "g_lock.h"
  27 #include "util_tdb.h"
  28 #include "../lib/util/tevent_ntstatus.h"
  29 #include "messages.h"
  30 #include "serverid.h"
  31
  32 struct g_lock_ctx {
  33         struct db_context *db;
  34         struct messaging_context *msg;
  35 };
  36
  37 /*
  38  * The "g_lock.tdb" file contains records, indexed by the 0-terminated
  39  * lockname. The record contains an array of "struct g_lock_rec"
  40  * structures.
  41  */
  42
  43 #define G_LOCK_REC_LENGTH (SERVER_ID_BUF_LENGTH+1)
  44
  45 static void g_lock_rec_put(uint8_t buf[G_LOCK_REC_LENGTH],
  46                            const struct g_lock_rec rec)
  47 {
  48         SCVAL(buf, 0, rec.lock_type);
  49         server_id_put(buf+1, rec.pid);
  50 }
  51
  52 static void g_lock_rec_get(struct g_lock_rec *rec,
  53                            const uint8_t buf[G_LOCK_REC_LENGTH])
  54 {
  55         rec->lock_type = CVAL(buf, 0);
  56         server_id_get(&rec->pid, buf+1);
  57 }
  58
  59 static ssize_t g_lock_put(uint8_t *buf, size_t buflen,
  60                           const struct g_lock_rec *locks,
  61                           size_t num_locks,
  62                           const uint8_t *data, size_t datalen)
  63 {
  64         size_t i, len, ofs;
  65
  66         if (num_locks > UINT32_MAX/G_LOCK_REC_LENGTH) {
  67                 return -1;
  68         }
  69
  70         len = num_locks * G_LOCK_REC_LENGTH;
  71
  72         len += sizeof(uint32_t);
  73         if (len < sizeof(uint32_t)) {
  74                 return -1;
  75         }
  76
  77         len += datalen;
  78         if (len < datalen) {
  79                 return -1;
  80         }
  81
  82         if (len > buflen) {
  83                 return len;
  84         }
  85
  86         ofs = 0;
  87         SIVAL(buf, ofs, num_locks);
  88         ofs += sizeof(uint32_t);
  89
  90         for (i=0; i<num_locks; i++) {
  91                 g_lock_rec_put(buf+ofs, locks[i]);
  92                 ofs += G_LOCK_REC_LENGTH;
  93         }
  94
  95         if ((data != NULL) && (datalen != 0)) {
  96                 memcpy(buf+ofs, data, datalen);
  97         }
  98
  99         return len;
 100 }
 101
 102 static ssize_t g_lock_get(TDB_DATA recval,
 103                           struct g_lock_rec *locks, size_t num_locks,
 104                           uint8_t **data, size_t *datalen)
 105 {
 106         size_t found_locks;
 107
 108         if (recval.dsize < sizeof(uint32_t)) {
 109                 /* Fresh or invalid record */
 110                 found_locks = 0;
 111                 goto done;
 112         }
 113
 114         found_locks = IVAL(recval.dptr, 0);
 115         recval.dptr += sizeof(uint32_t);
 116         recval.dsize -= sizeof(uint32_t);
 117
 118         if (found_locks > recval.dsize/G_LOCK_REC_LENGTH) {
 119                 /* Invalid record */
 120                 return 0;
 121         }
 122
 123         if (found_locks <= num_locks) {
 124                 size_t i;
 125
 126                 for (i=0; i<found_locks; i++) {
 127                         g_lock_rec_get(&locks[i], recval.dptr);
 128                         recval.dptr += G_LOCK_REC_LENGTH;
 129                         recval.dsize -= G_LOCK_REC_LENGTH;
 130                 }
 131         } else {
 132                 /*
 133                  * Not enough space passed in by the caller, don't
 134                  * parse the locks.
 135                  */
 136                 recval.dptr += found_locks * G_LOCK_REC_LENGTH;
 137                 recval.dsize -= found_locks * G_LOCK_REC_LENGTH;
 138         }
 139
 140 done:
 141         if (data != NULL) {
 142                 *data = recval.dptr;
 143         }
 144         if (datalen != NULL) {
 145                 *datalen = recval.dsize;
 146         }
 147         return found_locks;
 148 }
 149
 150 static NTSTATUS g_lock_get_talloc(TALLOC_CTX *mem_ctx, TDB_DATA recval,
 151                                   struct g_lock_rec **plocks,
 152                                   size_t *pnum_locks,
 153                                   uint8_t **data, size_t *datalen)
 154 {
 155         struct g_lock_rec *locks;
 156         ssize_t num_locks;
 157
 158         num_locks = g_lock_get(recval, NULL, 0, NULL, NULL);
 159         if (num_locks == -1) {
 160                 return NT_STATUS_INTERNAL_DB_CORRUPTION;
 161         }
 162         locks = talloc_array(mem_ctx, struct g_lock_rec, num_locks);
 163         if (locks == NULL) {
 164                 return NT_STATUS_NO_MEMORY;
 165         }
 166         g_lock_get(recval, locks, num_locks, data, datalen);
 167
 168         *plocks = locks;
 169         *pnum_locks = num_locks;
 170
 171         return NT_STATUS_OK;
 172 }
 173
 174 struct g_lock_ctx *g_lock_ctx_init(TALLOC_CTX *mem_ctx,
 175                                    struct messaging_context *msg)
 176 {
 177         struct g_lock_ctx *result;
 178         struct db_context *backend;
 179         char *db_path;
 180
 181         result = talloc(mem_ctx, struct g_lock_ctx);
 182         if (result == NULL) {
 183                 return NULL;
 184         }
 185         result->msg = msg;
 186
 187         db_path = lock_path("g_lock.tdb");
 188         if (db_path == NULL) {
 189                 TALLOC_FREE(result);
 190                 return NULL;
 191         }
 192
 193         backend = db_open(result, db_path, 0,
 194                           TDB_CLEAR_IF_FIRST|TDB_INCOMPATIBLE_HASH,
 195                           O_RDWR|O_CREAT, 0600,
 196                           DBWRAP_LOCK_ORDER_3,
 197                           DBWRAP_FLAG_NONE);
 198         TALLOC_FREE(db_path);
 199         if (backend == NULL) {
 200                 DEBUG(1, ("g_lock_init: Could not open g_lock.tdb\n"));
 201                 TALLOC_FREE(result);
 202                 return NULL;
 203         }
 204
 205         result->db = db_open_watched(result, backend, msg);
 206         if (result->db == NULL) {
 207                 DBG_WARNING("g_lock_init: db_open_watched failed\n");
 208                 TALLOC_FREE(result);
 209                 return NULL;
 210         }
 211         return result;
 212 }
 213
 214 static bool g_lock_conflicts(enum g_lock_type l1, enum g_lock_type l2)
 215 {
 216         /*
 217          * Only tested write locks so far. Very likely this routine
 218          * needs to be fixed for read locks....
 219          */
 220         if ((l1 == G_LOCK_READ) && (l2 == G_LOCK_READ)) {
 221                 return false;
 222         }
 223         return true;
 224 }
 225
 226 static NTSTATUS g_lock_record_store(struct db_record *rec,
 227                                     const struct g_lock_rec *locks,
 228                                     size_t num_locks,
 229                                     const uint8_t *data, size_t datalen)
 230 {
 231         ssize_t len;
 232         uint8_t *buf;
 233         NTSTATUS status;
 234
 235         len = g_lock_put(NULL, 0, locks, num_locks, data, datalen);
 236         if (len == -1) {
 237                 return NT_STATUS_BUFFER_TOO_SMALL;
 238         }
 239
 240         buf = talloc_array(rec, uint8_t, len);
 241         if (buf == NULL) {
 242                 return NT_STATUS_NO_MEMORY;
 243         }
 244
 245         g_lock_put(buf, len, locks, num_locks, data, datalen);
 246
 247         status = dbwrap_record_store(
 248                 rec, (TDB_DATA) { .dptr = buf, .dsize = len }, 0);
 249
 250         TALLOC_FREE(buf);
 251
 252         return status;
 253 }
 254
 255 static NTSTATUS g_lock_trylock(struct db_record *rec, struct server_id self,
 256                                enum g_lock_type type,
 257                                struct server_id *blocker)
 258 {
 259         TDB_DATA data, userdata;
 260         size_t i, num_locks;
 261         struct g_lock_rec *locks, *tmp;
 262         NTSTATUS status;
 263         bool modified = false;
 264
 265         data = dbwrap_record_get_value(rec);
 266
 267         status = g_lock_get_talloc(talloc_tos(), data, &locks, &num_locks,
 268                                    &userdata.dptr, &userdata.dsize);
 269         if (!NT_STATUS_IS_OK(status)) {
 270                 return status;
 271         }
 272
 273         if ((type == G_LOCK_READ) && (num_locks > 0)) {
 274                 /*
 275                  * Read locks can stay around forever if the process
 276                  * dies. Do a heuristic check for process existence:
 277                  * Check one random process for existence. Hopefully
 278                  * this will keep runaway read locks under control.
 279                  */
 280                 i = generate_random() % num_locks;
 281
 282                 if (!serverid_exists(&locks[i].pid)) {
 283                         locks[i] = locks[num_locks-1];
 284                         num_locks -=1;
 285                         modified = true;
 286                 }
 287         }
 288
 289         for (i=0; i<num_locks; i++) {
 290                 struct g_lock_rec *lock = &locks[i];
 291
 292                 if (serverid_equal(&self, &lock->pid)) {
 293                         if (lock->lock_type == type) {
 294                                 status = NT_STATUS_WAS_LOCKED;
 295                                 goto done;
 296                         }
 297                         /*
 298                          * Remove "our" lock entry. Re-add it later
 299                          * with our new lock type.
 300                          */
 301                         locks[i] = locks[num_locks-1];
 302                         num_locks -= 1;
 303                         continue;
 304                 }
 305
 306                 if (g_lock_conflicts(type, lock->lock_type)) {
 307                         struct server_id pid = lock->pid;
 308
 309                         /*
 310                          * As the serverid_exists might recurse into
 311                          * the g_lock code, we use
 312                          * SERVERID_UNIQUE_ID_NOT_TO_VERIFY to avoid the loop
 313                          */
 314                         pid.unique_id = SERVERID_UNIQUE_ID_NOT_TO_VERIFY;
 315
 316                         if (serverid_exists(&pid)) {
 317                                 status = NT_STATUS_LOCK_NOT_GRANTED;
 318                                 *blocker = lock->pid;
 319                                 goto done;
 320                         }
 321
 322                         /*
 323                          * Delete stale conflicting entry
 324                          */
 325                         locks[i] = locks[num_locks-1];
 326                         num_locks -= 1;
 327                         modified = true;
 328                 }
 329         }
 330
 331         tmp = talloc_realloc(talloc_tos(), locks, struct g_lock_rec,
 332                              num_locks+1);
 333         if (tmp == NULL) {
 334                 status = NT_STATUS_NO_MEMORY;
 335                 goto done;
 336         }
 337         locks = tmp;
 338
 339         locks[num_locks] = (struct g_lock_rec) {
 340                 .pid = self, .lock_type = type
 341         };
 342         num_locks +=1 ;
 343
 344         modified = true;
 345
 346         status = NT_STATUS_OK;
 347 done:
 348         if (modified) {
 349                 NTSTATUS store_status;
 350                 store_status = g_lock_record_store(
 351                         rec, locks, num_locks, userdata.dptr, userdata.dsize);
 352                 if (!NT_STATUS_IS_OK(store_status)) {
 353                         DBG_WARNING("g_lock_record_store failed: %s\n",
 354                                     nt_errstr(store_status));
 355                         status = store_status;
 356                 }
 357         }
 358         TALLOC_FREE(locks);
 359         return status;
 360 }
 361
 362 struct g_lock_lock_state {
 363         struct tevent_context *ev;
 364         struct g_lock_ctx *ctx;
 365         const char *name;
 366         enum g_lock_type type;
 367 };
 368
 369 static void g_lock_lock_retry(struct tevent_req *subreq);
 370
 371 struct tevent_req *g_lock_lock_send(TALLOC_CTX *mem_ctx,
 372                                     struct tevent_context *ev,
 373                                     struct g_lock_ctx *ctx,
 374                                     const char *name,
 375                                     enum g_lock_type type)
 376 {
 377         struct tevent_req *req, *subreq;
 378         struct g_lock_lock_state *state;
 379         struct db_record *rec;
 380         struct server_id self, blocker;
 381         NTSTATUS status;
 382
 383         req = tevent_req_create(mem_ctx, &state, struct g_lock_lock_state);
 384         if (req == NULL) {
 385                 return NULL;
 386         }
 387         state->ev = ev;
 388         state->ctx = ctx;
 389         state->name = name;
 390         state->type = type;
 391
 392         rec = dbwrap_fetch_locked(ctx->db, talloc_tos(),
 393                                   string_term_tdb_data(state->name));
 394         if (rec == NULL) {
 395                 DEBUG(10, ("fetch_locked(\"%s\") failed\n", name));
 396                 tevent_req_nterror(req, NT_STATUS_LOCK_NOT_GRANTED);
 397                 return tevent_req_post(req, ev);
 398         }
 399
 400         self = messaging_server_id(state->ctx->msg);
 401
 402         status = g_lock_trylock(rec, self, state->type, &blocker);
 403         if (NT_STATUS_IS_OK(status)) {
 404                 TALLOC_FREE(rec);
 405                 tevent_req_done(req);
 406                 return tevent_req_post(req, ev);
 407         }
 408         if (!NT_STATUS_EQUAL(status, NT_STATUS_LOCK_NOT_GRANTED)) {
 409                 TALLOC_FREE(rec);
 410                 tevent_req_nterror(req, status);
 411                 return tevent_req_post(req, ev);
 412         }
 413         subreq = dbwrap_watched_watch_send(state, state->ev, rec, blocker);
 414         TALLOC_FREE(rec);
 415         if (tevent_req_nomem(subreq, req)) {
 416                 return tevent_req_post(req, ev);
 417         }
 418         if (!tevent_req_set_endtime(
 419                     subreq, state->ev,
 420                     timeval_current_ofs(5 + sys_random() % 5, 0))) {
 421                 tevent_req_oom(req);
 422                 return tevent_req_post(req, ev);
 423         }
 424         tevent_req_set_callback(subreq, g_lock_lock_retry, req);
 425         return req;
 426 }
 427
 428 static void g_lock_lock_retry(struct tevent_req *subreq)
 429 {
 430         struct tevent_req *req = tevent_req_callback_data(
 431                 subreq, struct tevent_req);
 432         struct g_lock_lock_state *state = tevent_req_data(
 433                 req, struct g_lock_lock_state);
 434         struct server_id self = messaging_server_id(state->ctx->msg);
 435         struct server_id blocker;
 436         struct db_record *rec;
 437         NTSTATUS status;
 438
 439         status = dbwrap_watched_watch_recv(subreq, talloc_tos(), &rec, NULL,
 440                                            NULL);
 441         TALLOC_FREE(subreq);
 442
 443         if (NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT)) {
 444                 rec = dbwrap_fetch_locked(
 445                         state->ctx->db, talloc_tos(),
 446                         string_term_tdb_data(state->name));
 447                 if (rec == NULL) {
 448                         status = map_nt_error_from_unix(errno);
 449                 } else {
 450                         status = NT_STATUS_OK;
 451                 }
 452         }
 453
 454         if (tevent_req_nterror(req, status)) {
 455                 return;
 456         }
 457         status = g_lock_trylock(rec, self, state->type, &blocker);
 458         if (NT_STATUS_IS_OK(status)) {
 459                 TALLOC_FREE(rec);
 460                 tevent_req_done(req);
 461                 return;
 462         }
 463         if (!NT_STATUS_EQUAL(status, NT_STATUS_LOCK_NOT_GRANTED)) {
 464                 TALLOC_FREE(rec);
 465                 tevent_req_nterror(req, status);
 466                 return;
 467         }
 468         subreq = dbwrap_watched_watch_send(state, state->ev, rec, blocker);
 469         TALLOC_FREE(rec);
 470         if (tevent_req_nomem(subreq, req)) {
 471                 return;
 472         }
 473         if (!tevent_req_set_endtime(
 474                     subreq, state->ev,
 475                     timeval_current_ofs(5 + sys_random() % 5, 0))) {
 476                 tevent_req_oom(req);
 477                 return;
 478         }
 479         tevent_req_set_callback(subreq, g_lock_lock_retry, req);
 480         return;
 481
 482 }
 483
 484 NTSTATUS g_lock_lock_recv(struct tevent_req *req)
 485 {
 486         return tevent_req_simple_recv_ntstatus(req);
 487 }
 488
 489 NTSTATUS g_lock_lock(struct g_lock_ctx *ctx, const char *name,
 490                      enum g_lock_type type, struct timeval timeout)
 491 {
 492         TALLOC_CTX *frame = talloc_stackframe();
 493         struct tevent_context *ev;
 494         struct tevent_req *req;
 495         struct timeval end;
 496         NTSTATUS status = NT_STATUS_NO_MEMORY;
 497
 498         ev = samba_tevent_context_init(frame);
 499         if (ev == NULL) {
 500                 goto fail;
 501         }
 502         req = g_lock_lock_send(frame, ev, ctx, name, type);
 503         if (req == NULL) {
 504                 goto fail;
 505         }
 506         end = timeval_current_ofs(timeout.tv_sec, timeout.tv_usec);
 507         if (!tevent_req_set_endtime(req, ev, end)) {
 508                 goto fail;
 509         }
 510         if (!tevent_req_poll_ntstatus(req, ev, &status)) {
 511                 goto fail;
 512         }
 513         status = g_lock_lock_recv(req);
 514  fail:
 515         TALLOC_FREE(frame);
 516         return status;
 517 }
 518
 519 NTSTATUS g_lock_unlock(struct g_lock_ctx *ctx, const char *name)
 520 {
 521         struct server_id self = messaging_server_id(ctx->msg);
 522         struct db_record *rec = NULL;
 523         struct g_lock_rec *locks = NULL;
 524         size_t i, num_locks;
 525         NTSTATUS status;
 526         TDB_DATA value, userdata;
 527
 528         rec = dbwrap_fetch_locked(ctx->db, talloc_tos(),
 529                                   string_term_tdb_data(name));
 530         if (rec == NULL) {
 531                 DEBUG(10, ("fetch_locked(\"%s\") failed\n", name));
 532                 status = NT_STATUS_INTERNAL_ERROR;
 533                 goto done;
 534         }
 535
 536         value = dbwrap_record_get_value(rec);
 537
 538         status = g_lock_get_talloc(talloc_tos(), value, &locks, &num_locks,
 539                                    &userdata.dptr, &userdata.dsize);
 540         if (!NT_STATUS_IS_OK(status)) {
 541                 DBG_DEBUG("g_lock_get for %s failed: %s\n", name,
 542                           nt_errstr(status));
 543                 status = NT_STATUS_FILE_INVALID;
 544                 goto done;
 545         }
 546         for (i=0; i<num_locks; i++) {
 547                 if (serverid_equal(&self, &locks[i].pid)) {
 548                         break;
 549                 }
 550         }
 551         if (i == num_locks) {
 552                 DBG_DEBUG("Lock not found, num_locks=%zu\n", num_locks);
 553                 status = NT_STATUS_NOT_FOUND;
 554                 goto done;
 555         }
 556
 557         locks[i] = locks[num_locks-1];
 558         num_locks -= 1;
 559
 560         if ((num_locks == 0) && (userdata.dsize == 0)) {
 561                 status = dbwrap_record_delete(rec);
 562         } else {
 563                 status = g_lock_record_store(
 564                         rec, locks, num_locks, userdata.dptr, userdata.dsize);
 565         }
 566         if (!NT_STATUS_IS_OK(status)) {
 567                 DBG_WARNING("Could not store record: %s\n", nt_errstr(status));
 568                 goto done;
 569         }
 570
 571         status = NT_STATUS_OK;
 572 done:
 573         TALLOC_FREE(rec);
 574         TALLOC_FREE(locks);
 575         return status;
 576 }
 577
 578 NTSTATUS g_lock_write_data(struct g_lock_ctx *ctx, const char *name,
 579                            const uint8_t *buf, size_t buflen)
 580 {
 581         struct server_id self = messaging_server_id(ctx->msg);
 582         struct db_record *rec = NULL;
 583         struct g_lock_rec *locks = NULL;
 584         size_t i, num_locks;
 585         NTSTATUS status;
 586         TDB_DATA value;
 587
 588         rec = dbwrap_fetch_locked(ctx->db, talloc_tos(),
 589                                   string_term_tdb_data(name));
 590         if (rec == NULL) {
 591                 DEBUG(10, ("fetch_locked(\"%s\") failed\n", name));
 592                 status = NT_STATUS_INTERNAL_ERROR;
 593                 goto done;
 594         }
 595
 596         value = dbwrap_record_get_value(rec);
 597
 598         status = g_lock_get_talloc(talloc_tos(), value, &locks, &num_locks,
 599                                    NULL, NULL);
 600         if (!NT_STATUS_IS_OK(status)) {
 601                 DBG_DEBUG("g_lock_get for %s failed: %s\n", name,
 602                           nt_errstr(status));
 603                 status = NT_STATUS_FILE_INVALID;
 604                 goto done;
 605         }
 606
 607         for (i=0; i<num_locks; i++) {
 608                 if (server_id_equal(&self, &locks[i].pid) &&
 609                     (locks[i].lock_type == G_LOCK_WRITE)) {
 610                         break;
 611                 }
 612         }
 613         if (i == num_locks) {
 614                 DBG_DEBUG("Not locked by us\n");
 615                 status = NT_STATUS_NOT_LOCKED;
 616                 goto done;
 617         }
 618
 619         status = g_lock_record_store(rec, locks, num_locks, buf, buflen);
 620
 621 done:
 622         TALLOC_FREE(locks);
 623         TALLOC_FREE(rec);
 624         return status;
 625 }
 626
 627 struct g_lock_locks_state {
 628         int (*fn)(const char *name, void *private_data);
 629         void *private_data;
 630 };
 631
 632 static int g_lock_locks_fn(struct db_record *rec, void *priv)
 633 {
 634         TDB_DATA key;
 635         struct g_lock_locks_state *state = (struct g_lock_locks_state *)priv;
 636
 637         key = dbwrap_record_get_key(rec);
 638         if ((key.dsize == 0) || (key.dptr[key.dsize-1] != 0)) {
 639                 DEBUG(1, ("invalid key in g_lock.tdb, ignoring\n"));
 640                 return 0;
 641         }
 642         return state->fn((char *)key.dptr, state->private_data);
 643 }
 644
 645 int g_lock_locks(struct g_lock_ctx *ctx,
 646                  int (*fn)(const char *name, void *private_data),
 647                  void *private_data)
 648 {
 649         struct g_lock_locks_state state;
 650         NTSTATUS status;
 651         int count;
 652
 653         state.fn = fn;
 654         state.private_data = private_data;
 655
 656         status = dbwrap_traverse_read(ctx->db, g_lock_locks_fn, &state, &count);
 657         if (!NT_STATUS_IS_OK(status)) {
 658                 return -1;
 659         }
 660         return count;
 661 }
 662
 663 NTSTATUS g_lock_dump(struct g_lock_ctx *ctx, const char *name,
 664                      void (*fn)(const struct g_lock_rec *locks,
 665                                 size_t num_locks,
 666                                 const uint8_t *data,
 667                                 size_t datalen,
 668                                 void *private_data),
 669                      void *private_data)
 670 {
 671         TDB_DATA data;
 672         size_t num_locks;
 673         struct g_lock_rec *locks = NULL;
 674         uint8_t *userdata;
 675         size_t userdatalen;
 676         NTSTATUS status;
 677
 678         status = dbwrap_fetch_bystring(ctx->db, talloc_tos(), name, &data);
 679         if (!NT_STATUS_IS_OK(status)) {
 680                 return status;
 681         }
 682
 683         if ((data.dsize == 0) || (data.dptr == NULL)) {
 684                 return NT_STATUS_OK;
 685         }
 686
 687         status = g_lock_get_talloc(talloc_tos(), data, &locks, &num_locks,
 688                                    &userdata, &userdatalen);
 689
 690         if (!NT_STATUS_IS_OK(status)) {
 691                 DBG_DEBUG("g_lock_get for %s failed: %s\n", name,
 692                           nt_errstr(status));
 693                 TALLOC_FREE(data.dptr);
 694                 return NT_STATUS_INTERNAL_ERROR;
 695         }
 696
 697         fn(locks, num_locks, userdata, userdatalen, private_data);
 698
 699         TALLOC_FREE(locks);
 700         TALLOC_FREE(data.dptr);
 701         return NT_STATUS_OK;
 702 }
 703
 704 static bool g_lock_init_all(TALLOC_CTX *mem_ctx,
 705                             struct tevent_context **pev,
 706                             struct messaging_context **pmsg,
 707                             struct g_lock_ctx **pg_ctx)
 708 {
 709         struct tevent_context *ev = NULL;
 710         struct messaging_context *msg = NULL;
 711         struct g_lock_ctx *g_ctx = NULL;
 712
 713         ev = samba_tevent_context_init(mem_ctx);
 714         if (ev == NULL) {
 715                 d_fprintf(stderr, "ERROR: could not init event context\n");
 716                 goto fail;
 717         }
 718         msg = messaging_init(mem_ctx, ev);
 719         if (msg == NULL) {
 720                 d_fprintf(stderr, "ERROR: could not init messaging context\n");
 721                 goto fail;
 722         }
 723         g_ctx = g_lock_ctx_init(mem_ctx, msg);
 724         if (g_ctx == NULL) {
 725                 d_fprintf(stderr, "ERROR: could not init g_lock context\n");
 726                 goto fail;
 727         }
 728
 729         *pev = ev;
 730         *pmsg = msg;
 731         *pg_ctx = g_ctx;
 732         return true;
 733 fail:
 734         TALLOC_FREE(g_ctx);
 735         TALLOC_FREE(msg);
 736         TALLOC_FREE(ev);
 737         return false;
 738 }
 739
 740 NTSTATUS g_lock_do(const char *name, enum g_lock_type lock_type,
 741                    struct timeval timeout,
 742                    void (*fn)(void *private_data), void *private_data)
 743 {
 744         struct tevent_context *ev = NULL;
 745         struct messaging_context *msg = NULL;
 746         struct g_lock_ctx *g_ctx = NULL;
 747         NTSTATUS status;
 748
 749         if (!g_lock_init_all(talloc_tos(), &ev, &msg, &g_ctx)) {
 750                 status = NT_STATUS_ACCESS_DENIED;
 751                 goto done;
 752         }
 753
 754         status = g_lock_lock(g_ctx, name, lock_type, timeout);
 755         if (!NT_STATUS_IS_OK(status)) {
 756                 goto done;
 757         }
 758         fn(private_data);
 759         g_lock_unlock(g_ctx, name);
 760
 761 done:
 762         TALLOC_FREE(g_ctx);
 763         TALLOC_FREE(msg);
 764         TALLOC_FREE(ev);
 765         return status;
 766 }