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 "dbwrap/dbwrap.h"
  23 #include "dbwrap/dbwrap_open.h"
  24 #include "dbwrap/dbwrap_watch.h"
  25 #include "g_lock.h"
  26 #include "util_tdb.h"
  27 #include "ctdbd_conn.h"
  28 #include "../lib/util/select.h"
  29 #include "../lib/util/tevent_ntstatus.h"
  30 #include "system/select.h"
  31 #include "messages.h"
  32
  33 struct g_lock_ctx {
  34         struct db_context *db;
  35         struct messaging_context *msg;
  36 };
  37
  38 /*
  39  * The "g_lock.tdb" file contains records, indexed by the 0-terminated
  40  * lockname. The record contains an array of "struct g_lock_rec"
  41  * structures.
  42  */
  43
  44 struct g_lock_rec {
  45         enum g_lock_type lock_type;
  46         struct server_id pid;
  47 };
  48
  49 struct g_lock_ctx *g_lock_ctx_init(TALLOC_CTX *mem_ctx,
  50                                    struct messaging_context *msg)
  51 {
  52         struct g_lock_ctx *result;
  53
  54         result = talloc(mem_ctx, struct g_lock_ctx);
  55         if (result == NULL) {
  56                 return NULL;
  57         }
  58         result->msg = msg;
  59
  60         result->db = db_open(result, lock_path("g_lock.tdb"), 0,
  61                              TDB_CLEAR_IF_FIRST|TDB_INCOMPATIBLE_HASH,
  62                              O_RDWR|O_CREAT, 0600,
  63                              DBWRAP_LOCK_ORDER_2);
  64         if (result->db == NULL) {
  65                 DEBUG(1, ("g_lock_init: Could not open g_lock.tdb\n"));
  66                 TALLOC_FREE(result);
  67                 return NULL;
  68         }
  69         dbwrap_watch_db(result->db, msg);
  70         return result;
  71 }
  72
  73 static bool g_lock_conflicts(enum g_lock_type l1, enum g_lock_type l2)
  74 {
  75         /*
  76          * Only tested write locks so far. Very likely this routine
  77          * needs to be fixed for read locks....
  78          */
  79         if ((l1 == G_LOCK_READ) && (l2 == G_LOCK_READ)) {
  80                 return false;
  81         }
  82         return true;
  83 }
  84
  85 static bool g_lock_parse(TALLOC_CTX *mem_ctx, TDB_DATA data,
  86                          unsigned *pnum_locks, struct g_lock_rec **plocks)
  87 {
  88         unsigned num_locks;
  89         struct g_lock_rec *locks;
  90
  91         if ((data.dsize % sizeof(struct g_lock_rec)) != 0) {
  92                 DEBUG(1, ("invalid lock record length %d\n", (int)data.dsize));
  93                 return false;
  94         }
  95         num_locks = data.dsize / sizeof(struct g_lock_rec);
  96         locks = talloc_memdup(mem_ctx, data.dptr, data.dsize);
  97         if (locks == NULL) {
  98                 DEBUG(1, ("talloc_memdup failed\n"));
  99                 return false;
 100         }
 101         *plocks = locks;
 102         *pnum_locks = num_locks;
 103         return true;
 104 }
 105
 106 static NTSTATUS g_lock_trylock(struct db_record *rec, struct server_id self,
 107                                enum g_lock_type type)
 108 {
 109         TDB_DATA data;
 110         unsigned i, num_locks;
 111         struct g_lock_rec *locks, *tmp;
 112         NTSTATUS status;
 113         bool modified = false;
 114
 115         data = dbwrap_record_get_value(rec);
 116
 117         if (!g_lock_parse(talloc_tos(), data, &num_locks, &locks)) {
 118                 return NT_STATUS_INTERNAL_ERROR;
 119         }
 120
 121         for (i=0; i<num_locks; i++) {
 122                 if (serverid_equal(&self, &locks[i].pid)) {
 123                         status = NT_STATUS_INTERNAL_ERROR;
 124                         goto done;
 125                 }
 126                 if (g_lock_conflicts(type, locks[i].lock_type)) {
 127
 128                         if (process_exists(locks[i].pid)) {
 129                                 status = NT_STATUS_LOCK_NOT_GRANTED;
 130                                 goto done;
 131                         }
 132
 133                         /*
 134                          * Delete stale conflicting entry
 135                          */
 136                         locks[i] = locks[num_locks-1];
 137                         num_locks -= 1;
 138                         modified = true;
 139                 }
 140         }
 141
 142         tmp = talloc_realloc(talloc_tos(), locks, struct g_lock_rec,
 143                              num_locks+1);
 144         if (tmp == NULL) {
 145                 status = NT_STATUS_NO_MEMORY;
 146                 goto done;
 147         }
 148         locks = tmp;
 149
 150         ZERO_STRUCT(locks[num_locks]);
 151         locks[num_locks].pid = self;
 152         locks[num_locks].lock_type = type;
 153         num_locks += 1;
 154         modified = true;
 155
 156         status = NT_STATUS_OK;
 157 done:
 158         if (modified) {
 159                 NTSTATUS store_status;
 160
 161                 data = make_tdb_data((uint8_t *)locks, num_locks * sizeof(*locks));
 162                 store_status = dbwrap_record_store(rec, data, 0);
 163                 if (!NT_STATUS_IS_OK(store_status)) {
 164                         DEBUG(1, ("rec->store failed: %s\n",
 165                                   nt_errstr(store_status)));
 166                         status = store_status;
 167                 }
 168         }
 169         TALLOC_FREE(locks);
 170         return status;
 171 }
 172
 173 struct g_lock_lock_state {
 174         struct tevent_context *ev;
 175         struct g_lock_ctx *ctx;
 176         const char *name;
 177         enum g_lock_type type;
 178 };
 179
 180 static void g_lock_lock_retry(struct tevent_req *subreq);
 181
 182 struct tevent_req *g_lock_lock_send(TALLOC_CTX *mem_ctx,
 183                                     struct tevent_context *ev,
 184                                     struct g_lock_ctx *ctx,
 185                                     const char *name,
 186                                     enum g_lock_type type)
 187 {
 188         struct tevent_req *req, *subreq;
 189         struct g_lock_lock_state *state;
 190         struct db_record *rec;
 191         struct server_id self;
 192         NTSTATUS status;
 193
 194         req = tevent_req_create(mem_ctx, &state, struct g_lock_lock_state);
 195         if (req == NULL) {
 196                 return NULL;
 197         }
 198         state->ev = ev;
 199         state->ctx = ctx;
 200         state->name = name;
 201         state->type = type;
 202
 203         rec = dbwrap_fetch_locked(ctx->db, talloc_tos(),
 204                                   string_term_tdb_data(state->name));
 205         if (rec == NULL) {
 206                 DEBUG(10, ("fetch_locked(\"%s\") failed\n", name));
 207                 tevent_req_nterror(req, NT_STATUS_LOCK_NOT_GRANTED);
 208                 return tevent_req_post(req, ev);
 209         }
 210
 211         self = messaging_server_id(state->ctx->msg);
 212
 213         status = g_lock_trylock(rec, self, state->type);
 214         if (NT_STATUS_IS_OK(status)) {
 215                 TALLOC_FREE(rec);
 216                 tevent_req_done(req);
 217                 return tevent_req_post(req, ev);
 218         }
 219         if (!NT_STATUS_EQUAL(status, NT_STATUS_LOCK_NOT_GRANTED)) {
 220                 TALLOC_FREE(rec);
 221                 tevent_req_nterror(req, status);
 222                 return tevent_req_post(req, ev);
 223         }
 224         subreq = dbwrap_record_watch_send(state, state->ev, rec,
 225                                           state->ctx->msg);
 226         TALLOC_FREE(rec);
 227         if (tevent_req_nomem(subreq, req)) {
 228                 return tevent_req_post(req, ev);
 229         }
 230         if (!tevent_req_set_endtime(
 231                     subreq, state->ev,
 232                     timeval_current_ofs(5 + sys_random() % 5, 0))) {
 233                 tevent_req_oom(req);
 234                 return tevent_req_post(req, ev);
 235         }
 236         tevent_req_set_callback(subreq, g_lock_lock_retry, req);
 237         return req;
 238 }
 239
 240 static void g_lock_lock_retry(struct tevent_req *subreq)
 241 {
 242         struct tevent_req *req = tevent_req_callback_data(
 243                 subreq, struct tevent_req);
 244         struct g_lock_lock_state *state = tevent_req_data(
 245                 req, struct g_lock_lock_state);
 246         struct server_id self = messaging_server_id(state->ctx->msg);
 247         struct db_record *rec;
 248         NTSTATUS status;
 249
 250         status = dbwrap_record_watch_recv(subreq, talloc_tos(), &rec);
 251         TALLOC_FREE(subreq);
 252
 253         if (NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT)) {
 254                 rec = dbwrap_fetch_locked(
 255                         state->ctx->db, talloc_tos(),
 256                         string_term_tdb_data(state->name));
 257                 if (rec == NULL) {
 258                         status = map_nt_error_from_unix(errno);
 259                 } else {
 260                         status = NT_STATUS_OK;
 261                 }
 262         }
 263
 264         if (tevent_req_nterror(req, status)) {
 265                 return;
 266         }
 267         status = g_lock_trylock(rec, self, state->type);
 268         if (NT_STATUS_IS_OK(status)) {
 269                 TALLOC_FREE(rec);
 270                 tevent_req_done(req);
 271                 return;
 272         }
 273         if (!NT_STATUS_EQUAL(status, NT_STATUS_LOCK_NOT_GRANTED)) {
 274                 TALLOC_FREE(rec);
 275                 tevent_req_nterror(req, status);
 276                 return;
 277         }
 278         subreq = dbwrap_record_watch_send(state, state->ev, rec,
 279                                           state->ctx->msg);
 280         TALLOC_FREE(rec);
 281         if (tevent_req_nomem(subreq, req)) {
 282                 return;
 283         }
 284         if (!tevent_req_set_endtime(
 285                     subreq, state->ev,
 286                     timeval_current_ofs(5 + sys_random() % 5, 0))) {
 287                 tevent_req_oom(req);
 288                 return;
 289         }
 290         tevent_req_set_callback(subreq, g_lock_lock_retry, req);
 291         return;
 292
 293 }
 294
 295 NTSTATUS g_lock_lock_recv(struct tevent_req *req)
 296 {
 297         return tevent_req_simple_recv_ntstatus(req);
 298 }
 299
 300 NTSTATUS g_lock_lock(struct g_lock_ctx *ctx, const char *name,
 301                      enum g_lock_type type, struct timeval timeout)
 302 {
 303         TALLOC_CTX *frame = talloc_stackframe();
 304         struct tevent_context *ev;
 305         struct tevent_req *req;
 306         struct timeval end;
 307         NTSTATUS status = NT_STATUS_NO_MEMORY;
 308
 309         ev = tevent_context_init(frame);
 310         if (ev == NULL) {
 311                 goto fail;
 312         }
 313         req = g_lock_lock_send(frame, ev, ctx, name, type);
 314         if (req == NULL) {
 315                 goto fail;
 316         }
 317         end = timeval_current_ofs(timeout.tv_sec, timeout.tv_usec);
 318         if (!tevent_req_set_endtime(req, ev, end)) {
 319                 goto fail;
 320         }
 321         if (!tevent_req_poll_ntstatus(req, ev, &status)) {
 322                 goto fail;
 323         }
 324         status = g_lock_lock_recv(req);
 325  fail:
 326         TALLOC_FREE(frame);
 327         return status;
 328 }
 329
 330 NTSTATUS g_lock_unlock(struct g_lock_ctx *ctx, const char *name)
 331 {
 332         struct server_id self = messaging_server_id(ctx->msg);
 333         struct db_record *rec = NULL;
 334         struct g_lock_rec *locks = NULL;
 335         unsigned i, num_locks;
 336         NTSTATUS status;
 337         TDB_DATA value;
 338
 339         rec = dbwrap_fetch_locked(ctx->db, talloc_tos(),
 340                                   string_term_tdb_data(name));
 341         if (rec == NULL) {
 342                 DEBUG(10, ("fetch_locked(\"%s\") failed\n", name));
 343                 status = NT_STATUS_INTERNAL_ERROR;
 344                 goto done;
 345         }
 346
 347         value = dbwrap_record_get_value(rec);
 348
 349         if (!g_lock_parse(talloc_tos(), value, &num_locks, &locks)) {
 350                 DEBUG(10, ("g_lock_parse for %s failed\n", name));
 351                 status = NT_STATUS_FILE_INVALID;
 352                 goto done;
 353         }
 354         for (i=0; i<num_locks; i++) {
 355                 if (serverid_equal(&self, &locks[i].pid)) {
 356                         break;
 357                 }
 358         }
 359         if (i == num_locks) {
 360                 DEBUG(10, ("g_lock_force_unlock: Lock not found\n"));
 361                 status = NT_STATUS_NOT_FOUND;
 362                 goto done;
 363         }
 364
 365         locks[i] = locks[num_locks-1];
 366         num_locks -= 1;
 367
 368         if (num_locks == 0) {
 369                 status = dbwrap_record_delete(rec);
 370         } else {
 371                 TDB_DATA data;
 372                 data = make_tdb_data((uint8_t *)locks,
 373                                      sizeof(struct g_lock_rec) * num_locks);
 374                 status = dbwrap_record_store(rec, data, 0);
 375         }
 376         if (!NT_STATUS_IS_OK(status)) {
 377                 DEBUG(1, ("g_lock_force_unlock: Could not store record: %s\n",
 378                           nt_errstr(status)));
 379                 goto done;
 380         }
 381
 382         status = NT_STATUS_OK;
 383 done:
 384         TALLOC_FREE(rec);
 385         TALLOC_FREE(locks);
 386         return status;
 387 }
 388
 389 struct g_lock_locks_state {
 390         int (*fn)(const char *name, void *private_data);
 391         void *private_data;
 392 };
 393
 394 static int g_lock_locks_fn(struct db_record *rec, void *priv)
 395 {
 396         TDB_DATA key;
 397         struct g_lock_locks_state *state = (struct g_lock_locks_state *)priv;
 398
 399         key = dbwrap_record_get_key(rec);
 400         if ((key.dsize == 0) || (key.dptr[key.dsize-1] != 0)) {
 401                 DEBUG(1, ("invalid key in g_lock.tdb, ignoring\n"));
 402                 return 0;
 403         }
 404         return state->fn((char *)key.dptr, state->private_data);
 405 }
 406
 407 int g_lock_locks(struct g_lock_ctx *ctx,
 408                  int (*fn)(const char *name, void *private_data),
 409                  void *private_data)
 410 {
 411         struct g_lock_locks_state state;
 412         NTSTATUS status;
 413         int count;
 414
 415         state.fn = fn;
 416         state.private_data = private_data;
 417
 418         status = dbwrap_traverse_read(ctx->db, g_lock_locks_fn, &state, &count);
 419         if (!NT_STATUS_IS_OK(status)) {
 420                 return -1;
 421         } else {
 422                 return count;
 423         }
 424 }
 425
 426 NTSTATUS g_lock_dump(struct g_lock_ctx *ctx, const char *name,
 427                      int (*fn)(struct server_id pid,
 428                                enum g_lock_type lock_type,
 429                                void *private_data),
 430                      void *private_data)
 431 {
 432         TDB_DATA data;
 433         unsigned i, num_locks;
 434         struct g_lock_rec *locks = NULL;
 435         bool ret;
 436         NTSTATUS status;
 437
 438         status = dbwrap_fetch_bystring(ctx->db, talloc_tos(), name, &data);
 439         if (!NT_STATUS_IS_OK(status)) {
 440                 return status;
 441         }
 442
 443         if ((data.dsize == 0) || (data.dptr == NULL)) {
 444                 return NT_STATUS_OK;
 445         }
 446
 447         ret = g_lock_parse(talloc_tos(), data, &num_locks, &locks);
 448
 449         TALLOC_FREE(data.dptr);
 450
 451         if (!ret) {
 452                 DEBUG(10, ("g_lock_parse for %s failed\n", name));
 453                 return NT_STATUS_INTERNAL_ERROR;
 454         }
 455
 456         for (i=0; i<num_locks; i++) {
 457                 if (fn(locks[i].pid, locks[i].lock_type, private_data) != 0) {
 458                         break;
 459                 }
 460         }
 461         TALLOC_FREE(locks);
 462         return NT_STATUS_OK;
 463 }
 464
 465 struct g_lock_get_state {
 466         bool found;
 467         struct server_id *pid;
 468 };
 469
 470 static int g_lock_get_fn(struct server_id pid, enum g_lock_type lock_type,
 471                          void *priv)
 472 {
 473         struct g_lock_get_state *state = (struct g_lock_get_state *)priv;
 474         state->found = true;
 475         *state->pid = pid;
 476         return 1;
 477 }
 478
 479 NTSTATUS g_lock_get(struct g_lock_ctx *ctx, const char *name,
 480                     struct server_id *pid)
 481 {
 482         struct g_lock_get_state state;
 483         NTSTATUS status;
 484
 485         state.found = false;
 486         state.pid = pid;
 487
 488         status = g_lock_dump(ctx, name, g_lock_get_fn, &state);
 489         if (!NT_STATUS_IS_OK(status)) {
 490                 return status;
 491         }
 492         if (!state.found) {
 493                 return NT_STATUS_NOT_FOUND;
 494         }
 495         return NT_STATUS_OK;
 496 }
 497
 498 static bool g_lock_init_all(TALLOC_CTX *mem_ctx,
 499                             struct tevent_context **pev,
 500                             struct messaging_context **pmsg,
 501                             struct g_lock_ctx **pg_ctx)
 502 {
 503         struct tevent_context *ev = NULL;
 504         struct messaging_context *msg = NULL;
 505         struct g_lock_ctx *g_ctx = NULL;
 506
 507         ev = tevent_context_init(mem_ctx);
 508         if (ev == NULL) {
 509                 d_fprintf(stderr, "ERROR: could not init event context\n");
 510                 goto fail;
 511         }
 512         msg = messaging_init(mem_ctx, ev);
 513         if (msg == NULL) {
 514                 d_fprintf(stderr, "ERROR: could not init messaging context\n");
 515                 goto fail;
 516         }
 517         g_ctx = g_lock_ctx_init(mem_ctx, msg);
 518         if (g_ctx == NULL) {
 519                 d_fprintf(stderr, "ERROR: could not init g_lock context\n");
 520                 goto fail;
 521         }
 522
 523         *pev = ev;
 524         *pmsg = msg;
 525         *pg_ctx = g_ctx;
 526         return true;
 527 fail:
 528         TALLOC_FREE(g_ctx);
 529         TALLOC_FREE(msg);
 530         TALLOC_FREE(ev);
 531         return false;
 532 }
 533
 534 NTSTATUS g_lock_do(const char *name, enum g_lock_type lock_type,
 535                    struct timeval timeout,
 536                    void (*fn)(void *private_data), void *private_data)
 537 {
 538         struct tevent_context *ev = NULL;
 539         struct messaging_context *msg = NULL;
 540         struct g_lock_ctx *g_ctx = NULL;
 541         NTSTATUS status;
 542
 543         if (!g_lock_init_all(talloc_tos(), &ev, &msg, &g_ctx)) {
 544                 status = NT_STATUS_ACCESS_DENIED;
 545                 goto done;
 546         }
 547
 548         status = g_lock_lock(g_ctx, name, lock_type, timeout);
 549         if (!NT_STATUS_IS_OK(status)) {
 550                 goto done;
 551         }
 552         fn(private_data);
 553         g_lock_unlock(g_ctx, name);
 554
 555 done:
 556         TALLOC_FREE(g_ctx);
 557         TALLOC_FREE(msg);
 558         TALLOC_FREE(ev);
 559         return status;
 560 }