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_2,
 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, my_lock;
 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         my_lock = num_locks;    /* doesn't exist yet */
 274
 275         for (i=0; i<num_locks; i++) {
 276                 struct g_lock_rec *lock = &locks[i];
 277
 278                 if (serverid_equal(&self, &lock->pid)) {
 279                         if (lock->lock_type == type) {
 280                                 status = NT_STATUS_WAS_LOCKED;
 281                                 goto done;
 282                         }
 283                         my_lock = i;
 284                         break;
 285                 }
 286         }
 287
 288         for (i=0; i<num_locks; i++) {
 289
 290                 if (i == my_lock) {
 291                         continue;
 292                 }
 293
 294                 if (g_lock_conflicts(type, locks[i].lock_type)) {
 295                         struct server_id pid = locks[i].pid;
 296
 297                         /*
 298                          * As the serverid_exists might recurse into
 299                          * the g_lock code, we use
 300                          * SERVERID_UNIQUE_ID_NOT_TO_VERIFY to avoid the loop
 301                          */
 302                         pid.unique_id = SERVERID_UNIQUE_ID_NOT_TO_VERIFY;
 303
 304                         if (serverid_exists(&pid)) {
 305                                 status = NT_STATUS_LOCK_NOT_GRANTED;
 306                                 *blocker = locks[i].pid;
 307                                 goto done;
 308                         }
 309
 310                         /*
 311                          * Delete stale conflicting entry
 312                          */
 313                         locks[i] = locks[num_locks-1];
 314                         num_locks -= 1;
 315                         modified = true;
 316                 }
 317         }
 318
 319         if (my_lock >= num_locks) {
 320                 tmp = talloc_realloc(talloc_tos(), locks, struct g_lock_rec,
 321                                      num_locks+1);
 322                 if (tmp == NULL) {
 323                         status = NT_STATUS_NO_MEMORY;
 324                         goto done;
 325                 }
 326                 locks = tmp;
 327                 my_lock = num_locks;
 328                 num_locks += 1;
 329         }
 330
 331         locks[my_lock] = (struct g_lock_rec){ .pid = self, .lock_type = type };
 332         modified = true;
 333
 334         status = NT_STATUS_OK;
 335 done:
 336         if (modified) {
 337                 NTSTATUS store_status;
 338                 store_status = g_lock_record_store(
 339                         rec, locks, num_locks, userdata.dptr, userdata.dsize);
 340                 if (!NT_STATUS_IS_OK(store_status)) {
 341                         DBG_WARNING("g_lock_record_store failed: %s\n",
 342                                     nt_errstr(store_status));
 343                         status = store_status;
 344                 }
 345         }
 346         TALLOC_FREE(locks);
 347         return status;
 348 }
 349
 350 struct g_lock_lock_state {
 351         struct tevent_context *ev;
 352         struct g_lock_ctx *ctx;
 353         const char *name;
 354         enum g_lock_type type;
 355 };
 356
 357 static void g_lock_lock_retry(struct tevent_req *subreq);
 358
 359 struct tevent_req *g_lock_lock_send(TALLOC_CTX *mem_ctx,
 360                                     struct tevent_context *ev,
 361                                     struct g_lock_ctx *ctx,
 362                                     const char *name,
 363                                     enum g_lock_type type)
 364 {
 365         struct tevent_req *req, *subreq;
 366         struct g_lock_lock_state *state;
 367         struct db_record *rec;
 368         struct server_id self, blocker;
 369         NTSTATUS status;
 370
 371         req = tevent_req_create(mem_ctx, &state, struct g_lock_lock_state);
 372         if (req == NULL) {
 373                 return NULL;
 374         }
 375         state->ev = ev;
 376         state->ctx = ctx;
 377         state->name = name;
 378         state->type = type;
 379
 380         rec = dbwrap_fetch_locked(ctx->db, talloc_tos(),
 381                                   string_term_tdb_data(state->name));
 382         if (rec == NULL) {
 383                 DEBUG(10, ("fetch_locked(\"%s\") failed\n", name));
 384                 tevent_req_nterror(req, NT_STATUS_LOCK_NOT_GRANTED);
 385                 return tevent_req_post(req, ev);
 386         }
 387
 388         self = messaging_server_id(state->ctx->msg);
 389
 390         status = g_lock_trylock(rec, self, state->type, &blocker);
 391         if (NT_STATUS_IS_OK(status)) {
 392                 TALLOC_FREE(rec);
 393                 tevent_req_done(req);
 394                 return tevent_req_post(req, ev);
 395         }
 396         if (!NT_STATUS_EQUAL(status, NT_STATUS_LOCK_NOT_GRANTED)) {
 397                 TALLOC_FREE(rec);
 398                 tevent_req_nterror(req, status);
 399                 return tevent_req_post(req, ev);
 400         }
 401         subreq = dbwrap_watched_watch_send(state, state->ev, rec, blocker);
 402         TALLOC_FREE(rec);
 403         if (tevent_req_nomem(subreq, req)) {
 404                 return tevent_req_post(req, ev);
 405         }
 406         if (!tevent_req_set_endtime(
 407                     subreq, state->ev,
 408                     timeval_current_ofs(5 + sys_random() % 5, 0))) {
 409                 tevent_req_oom(req);
 410                 return tevent_req_post(req, ev);
 411         }
 412         tevent_req_set_callback(subreq, g_lock_lock_retry, req);
 413         return req;
 414 }
 415
 416 static void g_lock_lock_retry(struct tevent_req *subreq)
 417 {
 418         struct tevent_req *req = tevent_req_callback_data(
 419                 subreq, struct tevent_req);
 420         struct g_lock_lock_state *state = tevent_req_data(
 421                 req, struct g_lock_lock_state);
 422         struct server_id self = messaging_server_id(state->ctx->msg);
 423         struct server_id blocker;
 424         struct db_record *rec;
 425         NTSTATUS status;
 426
 427         status = dbwrap_watched_watch_recv(subreq, talloc_tos(), &rec, NULL,
 428                                            NULL);
 429         TALLOC_FREE(subreq);
 430
 431         if (NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT)) {
 432                 rec = dbwrap_fetch_locked(
 433                         state->ctx->db, talloc_tos(),
 434                         string_term_tdb_data(state->name));
 435                 if (rec == NULL) {
 436                         status = map_nt_error_from_unix(errno);
 437                 } else {
 438                         status = NT_STATUS_OK;
 439                 }
 440         }
 441
 442         if (tevent_req_nterror(req, status)) {
 443                 return;
 444         }
 445         status = g_lock_trylock(rec, self, state->type, &blocker);
 446         if (NT_STATUS_IS_OK(status)) {
 447                 TALLOC_FREE(rec);
 448                 tevent_req_done(req);
 449                 return;
 450         }
 451         if (!NT_STATUS_EQUAL(status, NT_STATUS_LOCK_NOT_GRANTED)) {
 452                 TALLOC_FREE(rec);
 453                 tevent_req_nterror(req, status);
 454                 return;
 455         }
 456         subreq = dbwrap_watched_watch_send(state, state->ev, rec, blocker);
 457         TALLOC_FREE(rec);
 458         if (tevent_req_nomem(subreq, req)) {
 459                 return;
 460         }
 461         if (!tevent_req_set_endtime(
 462                     subreq, state->ev,
 463                     timeval_current_ofs(5 + sys_random() % 5, 0))) {
 464                 tevent_req_oom(req);
 465                 return;
 466         }
 467         tevent_req_set_callback(subreq, g_lock_lock_retry, req);
 468         return;
 469
 470 }
 471
 472 NTSTATUS g_lock_lock_recv(struct tevent_req *req)
 473 {
 474         return tevent_req_simple_recv_ntstatus(req);
 475 }
 476
 477 NTSTATUS g_lock_lock(struct g_lock_ctx *ctx, const char *name,
 478                      enum g_lock_type type, struct timeval timeout)
 479 {
 480         TALLOC_CTX *frame = talloc_stackframe();
 481         struct tevent_context *ev;
 482         struct tevent_req *req;
 483         struct timeval end;
 484         NTSTATUS status = NT_STATUS_NO_MEMORY;
 485
 486         ev = samba_tevent_context_init(frame);
 487         if (ev == NULL) {
 488                 goto fail;
 489         }
 490         req = g_lock_lock_send(frame, ev, ctx, name, type);
 491         if (req == NULL) {
 492                 goto fail;
 493         }
 494         end = timeval_current_ofs(timeout.tv_sec, timeout.tv_usec);
 495         if (!tevent_req_set_endtime(req, ev, end)) {
 496                 goto fail;
 497         }
 498         if (!tevent_req_poll_ntstatus(req, ev, &status)) {
 499                 goto fail;
 500         }
 501         status = g_lock_lock_recv(req);
 502  fail:
 503         TALLOC_FREE(frame);
 504         return status;
 505 }
 506
 507 NTSTATUS g_lock_unlock(struct g_lock_ctx *ctx, const char *name)
 508 {
 509         struct server_id self = messaging_server_id(ctx->msg);
 510         struct db_record *rec = NULL;
 511         struct g_lock_rec *locks = NULL;
 512         size_t i, num_locks;
 513         NTSTATUS status;
 514         TDB_DATA value, userdata;
 515
 516         rec = dbwrap_fetch_locked(ctx->db, talloc_tos(),
 517                                   string_term_tdb_data(name));
 518         if (rec == NULL) {
 519                 DEBUG(10, ("fetch_locked(\"%s\") failed\n", name));
 520                 status = NT_STATUS_INTERNAL_ERROR;
 521                 goto done;
 522         }
 523
 524         value = dbwrap_record_get_value(rec);
 525
 526         status = g_lock_get_talloc(talloc_tos(), value, &locks, &num_locks,
 527                                    &userdata.dptr, &userdata.dsize);
 528         if (!NT_STATUS_IS_OK(status)) {
 529                 DBG_DEBUG("g_lock_get for %s failed: %s\n", name,
 530                           nt_errstr(status));
 531                 status = NT_STATUS_FILE_INVALID;
 532                 goto done;
 533         }
 534         for (i=0; i<num_locks; i++) {
 535                 if (serverid_equal(&self, &locks[i].pid)) {
 536                         break;
 537                 }
 538         }
 539         if (i == num_locks) {
 540                 DBG_DEBUG("Lock not found, num_locks=%zu\n", num_locks);
 541                 status = NT_STATUS_NOT_FOUND;
 542                 goto done;
 543         }
 544
 545         locks[i] = locks[num_locks-1];
 546         num_locks -= 1;
 547
 548         if ((num_locks == 0) && (userdata.dsize == 0)) {
 549                 status = dbwrap_record_delete(rec);
 550         } else {
 551                 status = g_lock_record_store(
 552                         rec, locks, num_locks, userdata.dptr, userdata.dsize);
 553         }
 554         if (!NT_STATUS_IS_OK(status)) {
 555                 DBG_WARNING("Could not store record: %s\n", nt_errstr(status));
 556                 goto done;
 557         }
 558
 559         status = NT_STATUS_OK;
 560 done:
 561         TALLOC_FREE(rec);
 562         TALLOC_FREE(locks);
 563         return status;
 564 }
 565
 566 NTSTATUS g_lock_write_data(struct g_lock_ctx *ctx, const char *name,
 567                            const uint8_t *buf, size_t buflen)
 568 {
 569         struct server_id self = messaging_server_id(ctx->msg);
 570         struct db_record *rec = NULL;
 571         struct g_lock_rec *locks = NULL;
 572         size_t i, num_locks;
 573         NTSTATUS status;
 574         TDB_DATA value;
 575
 576         rec = dbwrap_fetch_locked(ctx->db, talloc_tos(),
 577                                   string_term_tdb_data(name));
 578         if (rec == NULL) {
 579                 DEBUG(10, ("fetch_locked(\"%s\") failed\n", name));
 580                 status = NT_STATUS_INTERNAL_ERROR;
 581                 goto done;
 582         }
 583
 584         value = dbwrap_record_get_value(rec);
 585
 586         status = g_lock_get_talloc(talloc_tos(), value, &locks, &num_locks,
 587                                    NULL, NULL);
 588         if (!NT_STATUS_IS_OK(status)) {
 589                 DBG_DEBUG("g_lock_get for %s failed: %s\n", name,
 590                           nt_errstr(status));
 591                 status = NT_STATUS_FILE_INVALID;
 592                 goto done;
 593         }
 594
 595         for (i=0; i<num_locks; i++) {
 596                 if (server_id_equal(&self, &locks[i].pid) &&
 597                     (locks[i].lock_type == G_LOCK_WRITE)) {
 598                         break;
 599                 }
 600         }
 601         if (i == num_locks) {
 602                 DBG_DEBUG("Not locked by us\n");
 603                 status = NT_STATUS_NOT_LOCKED;
 604                 goto done;
 605         }
 606
 607         status = g_lock_record_store(rec, locks, num_locks, buf, buflen);
 608
 609 done:
 610         TALLOC_FREE(locks);
 611         TALLOC_FREE(rec);
 612         return status;
 613 }
 614
 615 struct g_lock_locks_state {
 616         int (*fn)(const char *name, void *private_data);
 617         void *private_data;
 618 };
 619
 620 static int g_lock_locks_fn(struct db_record *rec, void *priv)
 621 {
 622         TDB_DATA key;
 623         struct g_lock_locks_state *state = (struct g_lock_locks_state *)priv;
 624
 625         key = dbwrap_record_get_key(rec);
 626         if ((key.dsize == 0) || (key.dptr[key.dsize-1] != 0)) {
 627                 DEBUG(1, ("invalid key in g_lock.tdb, ignoring\n"));
 628                 return 0;
 629         }
 630         return state->fn((char *)key.dptr, state->private_data);
 631 }
 632
 633 int g_lock_locks(struct g_lock_ctx *ctx,
 634                  int (*fn)(const char *name, void *private_data),
 635                  void *private_data)
 636 {
 637         struct g_lock_locks_state state;
 638         NTSTATUS status;
 639         int count;
 640
 641         state.fn = fn;
 642         state.private_data = private_data;
 643
 644         status = dbwrap_traverse_read(ctx->db, g_lock_locks_fn, &state, &count);
 645         if (!NT_STATUS_IS_OK(status)) {
 646                 return -1;
 647         }
 648         return count;
 649 }
 650
 651 NTSTATUS g_lock_dump(struct g_lock_ctx *ctx, const char *name,
 652                      void (*fn)(const struct g_lock_rec *locks,
 653                                 size_t num_locks,
 654                                 const uint8_t *data,
 655                                 size_t datalen,
 656                                 void *private_data),
 657                      void *private_data)
 658 {
 659         TDB_DATA data;
 660         size_t num_locks;
 661         struct g_lock_rec *locks = NULL;
 662         uint8_t *userdata;
 663         size_t userdatalen;
 664         NTSTATUS status;
 665
 666         status = dbwrap_fetch_bystring(ctx->db, talloc_tos(), name, &data);
 667         if (!NT_STATUS_IS_OK(status)) {
 668                 return status;
 669         }
 670
 671         if ((data.dsize == 0) || (data.dptr == NULL)) {
 672                 return NT_STATUS_OK;
 673         }
 674
 675         status = g_lock_get_talloc(talloc_tos(), data, &locks, &num_locks,
 676                                    &userdata, &userdatalen);
 677
 678         if (!NT_STATUS_IS_OK(status)) {
 679                 DBG_DEBUG("g_lock_get for %s failed: %s\n", name,
 680                           nt_errstr(status));
 681                 TALLOC_FREE(data.dptr);
 682                 return NT_STATUS_INTERNAL_ERROR;
 683         }
 684
 685         fn(locks, num_locks, userdata, userdatalen, private_data);
 686
 687         TALLOC_FREE(locks);
 688         TALLOC_FREE(data.dptr);
 689         return NT_STATUS_OK;
 690 }
 691
 692 static bool g_lock_init_all(TALLOC_CTX *mem_ctx,
 693                             struct tevent_context **pev,
 694                             struct messaging_context **pmsg,
 695                             struct g_lock_ctx **pg_ctx)
 696 {
 697         struct tevent_context *ev = NULL;
 698         struct messaging_context *msg = NULL;
 699         struct g_lock_ctx *g_ctx = NULL;
 700
 701         ev = samba_tevent_context_init(mem_ctx);
 702         if (ev == NULL) {
 703                 d_fprintf(stderr, "ERROR: could not init event context\n");
 704                 goto fail;
 705         }
 706         msg = messaging_init(mem_ctx, ev);
 707         if (msg == NULL) {
 708                 d_fprintf(stderr, "ERROR: could not init messaging context\n");
 709                 goto fail;
 710         }
 711         g_ctx = g_lock_ctx_init(mem_ctx, msg);
 712         if (g_ctx == NULL) {
 713                 d_fprintf(stderr, "ERROR: could not init g_lock context\n");
 714                 goto fail;
 715         }
 716
 717         *pev = ev;
 718         *pmsg = msg;
 719         *pg_ctx = g_ctx;
 720         return true;
 721 fail:
 722         TALLOC_FREE(g_ctx);
 723         TALLOC_FREE(msg);
 724         TALLOC_FREE(ev);
 725         return false;
 726 }
 727
 728 NTSTATUS g_lock_do(const char *name, enum g_lock_type lock_type,
 729                    struct timeval timeout,
 730                    void (*fn)(void *private_data), void *private_data)
 731 {
 732         struct tevent_context *ev = NULL;
 733         struct messaging_context *msg = NULL;
 734         struct g_lock_ctx *g_ctx = NULL;
 735         NTSTATUS status;
 736
 737         if (!g_lock_init_all(talloc_tos(), &ev, &msg, &g_ctx)) {
 738                 status = NT_STATUS_ACCESS_DENIED;
 739                 goto done;
 740         }
 741
 742         status = g_lock_lock(g_ctx, name, lock_type, timeout);
 743         if (!NT_STATUS_IS_OK(status)) {
 744                 goto done;
 745         }
 746         fn(private_data);
 747         g_lock_unlock(g_ctx, name);
 748
 749 done:
 750         TALLOC_FREE(g_ctx);
 751         TALLOC_FREE(msg);
 752         TALLOC_FREE(ev);
 753         return status;
 754 }