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 #include "serverid.h"
  33
  34 struct g_lock_ctx {
  35         struct db_context *db;
  36         struct messaging_context *msg;
  37 };
  38
  39 /*
  40  * The "g_lock.tdb" file contains records, indexed by the 0-terminated
  41  * lockname. The record contains an array of "struct g_lock_rec"
  42  * structures.
  43  */
  44
  45 struct g_lock_rec {
  46         enum g_lock_type lock_type;
  47         struct server_id pid;
  48 };
  49
  50 struct g_lock_ctx *g_lock_ctx_init(TALLOC_CTX *mem_ctx,
  51                                    struct messaging_context *msg)
  52 {
  53         struct g_lock_ctx *result;
  54
  55         result = talloc(mem_ctx, struct g_lock_ctx);
  56         if (result == NULL) {
  57                 return NULL;
  58         }
  59         result->msg = msg;
  60
  61         result->db = db_open(result, lock_path("g_lock.tdb"), 0,
  62                              TDB_CLEAR_IF_FIRST|TDB_INCOMPATIBLE_HASH,
  63                              O_RDWR|O_CREAT, 0600,
  64                              DBWRAP_LOCK_ORDER_2,
  65                              DBWRAP_FLAG_NONE);
  66         if (result->db == NULL) {
  67                 DEBUG(1, ("g_lock_init: Could not open g_lock.tdb\n"));
  68                 TALLOC_FREE(result);
  69                 return NULL;
  70         }
  71         dbwrap_watch_db(result->db, msg);
  72         return result;
  73 }
  74
  75 static bool g_lock_conflicts(enum g_lock_type l1, enum g_lock_type l2)
  76 {
  77         /*
  78          * Only tested write locks so far. Very likely this routine
  79          * needs to be fixed for read locks....
  80          */
  81         if ((l1 == G_LOCK_READ) && (l2 == G_LOCK_READ)) {
  82                 return false;
  83         }
  84         return true;
  85 }
  86
  87 static bool g_lock_parse(TALLOC_CTX *mem_ctx, TDB_DATA data,
  88                          unsigned *pnum_locks, struct g_lock_rec **plocks)
  89 {
  90         unsigned num_locks;
  91         struct g_lock_rec *locks;
  92
  93         if ((data.dsize % sizeof(struct g_lock_rec)) != 0) {
  94                 DEBUG(1, ("invalid lock record length %d\n", (int)data.dsize));
  95                 return false;
  96         }
  97         num_locks = data.dsize / sizeof(struct g_lock_rec);
  98         locks = talloc_memdup(mem_ctx, data.dptr, data.dsize);
  99         if (locks == NULL) {
 100                 DEBUG(1, ("talloc_memdup failed\n"));
 101                 return false;
 102         }
 103         *plocks = locks;
 104         *pnum_locks = num_locks;
 105         return true;
 106 }
 107
 108 static NTSTATUS g_lock_trylock(struct db_record *rec, struct server_id self,
 109                                enum g_lock_type type)
 110 {
 111         TDB_DATA data;
 112         unsigned i, num_locks;
 113         struct g_lock_rec *locks, *tmp;
 114         NTSTATUS status;
 115         bool modified = false;
 116
 117         data = dbwrap_record_get_value(rec);
 118
 119         if (!g_lock_parse(talloc_tos(), data, &num_locks, &locks)) {
 120                 return NT_STATUS_INTERNAL_ERROR;
 121         }
 122
 123         for (i=0; i<num_locks; i++) {
 124                 if (serverid_equal(&self, &locks[i].pid)) {
 125                         status = NT_STATUS_INTERNAL_ERROR;
 126                         goto done;
 127                 }
 128                 if (g_lock_conflicts(type, locks[i].lock_type)) {
 129                         struct server_id pid = locks[i].pid;
 130
 131                         /*
 132                          * As the serverid_exists might recurse into
 133                          * the g_lock code, we use
 134                          * SERVERID_UNIQUE_ID_NOT_TO_VERIFY to avoid the loop
 135                          */
 136                         pid.unique_id = SERVERID_UNIQUE_ID_NOT_TO_VERIFY;
 137
 138                         if (serverid_exists(&pid)) {
 139                                 status = NT_STATUS_LOCK_NOT_GRANTED;
 140                                 goto done;
 141                         }
 142
 143                         /*
 144                          * Delete stale conflicting entry
 145                          */
 146                         locks[i] = locks[num_locks-1];
 147                         num_locks -= 1;
 148                         modified = true;
 149                 }
 150         }
 151
 152         tmp = talloc_realloc(talloc_tos(), locks, struct g_lock_rec,
 153                              num_locks+1);
 154         if (tmp == NULL) {
 155                 status = NT_STATUS_NO_MEMORY;
 156                 goto done;
 157         }
 158         locks = tmp;
 159
 160         ZERO_STRUCT(locks[num_locks]);
 161         locks[num_locks].pid = self;
 162         locks[num_locks].lock_type = type;
 163         num_locks += 1;
 164         modified = true;
 165
 166         status = NT_STATUS_OK;
 167 done:
 168         if (modified) {
 169                 NTSTATUS store_status;
 170
 171                 data = make_tdb_data((uint8_t *)locks, num_locks * sizeof(*locks));
 172                 store_status = dbwrap_record_store(rec, data, 0);
 173                 if (!NT_STATUS_IS_OK(store_status)) {
 174                         DEBUG(1, ("rec->store failed: %s\n",
 175                                   nt_errstr(store_status)));
 176                         status = store_status;
 177                 }
 178         }
 179         TALLOC_FREE(locks);
 180         return status;
 181 }
 182
 183 struct g_lock_lock_state {
 184         struct tevent_context *ev;
 185         struct g_lock_ctx *ctx;
 186         const char *name;
 187         enum g_lock_type type;
 188 };
 189
 190 static void g_lock_lock_retry(struct tevent_req *subreq);
 191
 192 struct tevent_req *g_lock_lock_send(TALLOC_CTX *mem_ctx,
 193                                     struct tevent_context *ev,
 194                                     struct g_lock_ctx *ctx,
 195                                     const char *name,
 196                                     enum g_lock_type type)
 197 {
 198         struct tevent_req *req, *subreq;
 199         struct g_lock_lock_state *state;
 200         struct db_record *rec;
 201         struct server_id self;
 202         NTSTATUS status;
 203
 204         req = tevent_req_create(mem_ctx, &state, struct g_lock_lock_state);
 205         if (req == NULL) {
 206                 return NULL;
 207         }
 208         state->ev = ev;
 209         state->ctx = ctx;
 210         state->name = name;
 211         state->type = type;
 212
 213         rec = dbwrap_fetch_locked(ctx->db, talloc_tos(),
 214                                   string_term_tdb_data(state->name));
 215         if (rec == NULL) {
 216                 DEBUG(10, ("fetch_locked(\"%s\") failed\n", name));
 217                 tevent_req_nterror(req, NT_STATUS_LOCK_NOT_GRANTED);
 218                 return tevent_req_post(req, ev);
 219         }
 220
 221         self = messaging_server_id(state->ctx->msg);
 222
 223         status = g_lock_trylock(rec, self, state->type);
 224         if (NT_STATUS_IS_OK(status)) {
 225                 TALLOC_FREE(rec);
 226                 tevent_req_done(req);
 227                 return tevent_req_post(req, ev);
 228         }
 229         if (!NT_STATUS_EQUAL(status, NT_STATUS_LOCK_NOT_GRANTED)) {
 230                 TALLOC_FREE(rec);
 231                 tevent_req_nterror(req, status);
 232                 return tevent_req_post(req, ev);
 233         }
 234         subreq = dbwrap_record_watch_send(state, state->ev, rec,
 235                                           state->ctx->msg);
 236         TALLOC_FREE(rec);
 237         if (tevent_req_nomem(subreq, req)) {
 238                 return tevent_req_post(req, ev);
 239         }
 240         if (!tevent_req_set_endtime(
 241                     subreq, state->ev,
 242                     timeval_current_ofs(5 + sys_random() % 5, 0))) {
 243                 tevent_req_oom(req);
 244                 return tevent_req_post(req, ev);
 245         }
 246         tevent_req_set_callback(subreq, g_lock_lock_retry, req);
 247         return req;
 248 }
 249
 250 static void g_lock_lock_retry(struct tevent_req *subreq)
 251 {
 252         struct tevent_req *req = tevent_req_callback_data(
 253                 subreq, struct tevent_req);
 254         struct g_lock_lock_state *state = tevent_req_data(
 255                 req, struct g_lock_lock_state);
 256         struct server_id self = messaging_server_id(state->ctx->msg);
 257         struct db_record *rec;
 258         NTSTATUS status;
 259
 260         status = dbwrap_record_watch_recv(subreq, talloc_tos(), &rec);
 261         TALLOC_FREE(subreq);
 262
 263         if (NT_STATUS_EQUAL(status, NT_STATUS_IO_TIMEOUT)) {
 264                 rec = dbwrap_fetch_locked(
 265                         state->ctx->db, talloc_tos(),
 266                         string_term_tdb_data(state->name));
 267                 if (rec == NULL) {
 268                         status = map_nt_error_from_unix(errno);
 269                 } else {
 270                         status = NT_STATUS_OK;
 271                 }
 272         }
 273
 274         if (tevent_req_nterror(req, status)) {
 275                 return;
 276         }
 277         status = g_lock_trylock(rec, self, state->type);
 278         if (NT_STATUS_IS_OK(status)) {
 279                 TALLOC_FREE(rec);
 280                 tevent_req_done(req);
 281                 return;
 282         }
 283         if (!NT_STATUS_EQUAL(status, NT_STATUS_LOCK_NOT_GRANTED)) {
 284                 TALLOC_FREE(rec);
 285                 tevent_req_nterror(req, status);
 286                 return;
 287         }
 288         subreq = dbwrap_record_watch_send(state, state->ev, rec,
 289                                           state->ctx->msg);
 290         TALLOC_FREE(rec);
 291         if (tevent_req_nomem(subreq, req)) {
 292                 return;
 293         }
 294         if (!tevent_req_set_endtime(
 295                     subreq, state->ev,
 296                     timeval_current_ofs(5 + sys_random() % 5, 0))) {
 297                 tevent_req_oom(req);
 298                 return;
 299         }
 300         tevent_req_set_callback(subreq, g_lock_lock_retry, req);
 301         return;
 302
 303 }
 304
 305 NTSTATUS g_lock_lock_recv(struct tevent_req *req)
 306 {
 307         return tevent_req_simple_recv_ntstatus(req);
 308 }
 309
 310 NTSTATUS g_lock_lock(struct g_lock_ctx *ctx, const char *name,
 311                      enum g_lock_type type, struct timeval timeout)
 312 {
 313         TALLOC_CTX *frame = talloc_stackframe();
 314         struct tevent_context *ev;
 315         struct tevent_req *req;
 316         struct timeval end;
 317         NTSTATUS status = NT_STATUS_NO_MEMORY;
 318
 319         ev = samba_tevent_context_init(frame);
 320         if (ev == NULL) {
 321                 goto fail;
 322         }
 323         req = g_lock_lock_send(frame, ev, ctx, name, type);
 324         if (req == NULL) {
 325                 goto fail;
 326         }
 327         end = timeval_current_ofs(timeout.tv_sec, timeout.tv_usec);
 328         if (!tevent_req_set_endtime(req, ev, end)) {
 329                 goto fail;
 330         }
 331         if (!tevent_req_poll_ntstatus(req, ev, &status)) {
 332                 goto fail;
 333         }
 334         status = g_lock_lock_recv(req);
 335  fail:
 336         TALLOC_FREE(frame);
 337         return status;
 338 }
 339
 340 NTSTATUS g_lock_unlock(struct g_lock_ctx *ctx, const char *name)
 341 {
 342         struct server_id self = messaging_server_id(ctx->msg);
 343         struct db_record *rec = NULL;
 344         struct g_lock_rec *locks = NULL;
 345         unsigned i, num_locks;
 346         NTSTATUS status;
 347         TDB_DATA value;
 348
 349         rec = dbwrap_fetch_locked(ctx->db, talloc_tos(),
 350                                   string_term_tdb_data(name));
 351         if (rec == NULL) {
 352                 DEBUG(10, ("fetch_locked(\"%s\") failed\n", name));
 353                 status = NT_STATUS_INTERNAL_ERROR;
 354                 goto done;
 355         }
 356
 357         value = dbwrap_record_get_value(rec);
 358
 359         if (!g_lock_parse(talloc_tos(), value, &num_locks, &locks)) {
 360                 DEBUG(10, ("g_lock_parse for %s failed\n", name));
 361                 status = NT_STATUS_FILE_INVALID;
 362                 goto done;
 363         }
 364         for (i=0; i<num_locks; i++) {
 365                 if (serverid_equal(&self, &locks[i].pid)) {
 366                         break;
 367                 }
 368         }
 369         if (i == num_locks) {
 370                 DEBUG(10, ("g_lock_force_unlock: Lock not found\n"));
 371                 status = NT_STATUS_NOT_FOUND;
 372                 goto done;
 373         }
 374
 375         locks[i] = locks[num_locks-1];
 376         num_locks -= 1;
 377
 378         if (num_locks == 0) {
 379                 status = dbwrap_record_delete(rec);
 380         } else {
 381                 TDB_DATA data;
 382                 data = make_tdb_data((uint8_t *)locks,
 383                                      sizeof(struct g_lock_rec) * num_locks);
 384                 status = dbwrap_record_store(rec, data, 0);
 385         }
 386         if (!NT_STATUS_IS_OK(status)) {
 387                 DEBUG(1, ("g_lock_force_unlock: Could not store record: %s\n",
 388                           nt_errstr(status)));
 389                 goto done;
 390         }
 391
 392         status = NT_STATUS_OK;
 393 done:
 394         TALLOC_FREE(rec);
 395         TALLOC_FREE(locks);
 396         return status;
 397 }
 398
 399 struct g_lock_locks_state {
 400         int (*fn)(const char *name, void *private_data);
 401         void *private_data;
 402 };
 403
 404 static int g_lock_locks_fn(struct db_record *rec, void *priv)
 405 {
 406         TDB_DATA key;
 407         struct g_lock_locks_state *state = (struct g_lock_locks_state *)priv;
 408
 409         key = dbwrap_record_get_key(rec);
 410         if ((key.dsize == 0) || (key.dptr[key.dsize-1] != 0)) {
 411                 DEBUG(1, ("invalid key in g_lock.tdb, ignoring\n"));
 412                 return 0;
 413         }
 414         return state->fn((char *)key.dptr, state->private_data);
 415 }
 416
 417 int g_lock_locks(struct g_lock_ctx *ctx,
 418                  int (*fn)(const char *name, void *private_data),
 419                  void *private_data)
 420 {
 421         struct g_lock_locks_state state;
 422         NTSTATUS status;
 423         int count;
 424
 425         state.fn = fn;
 426         state.private_data = private_data;
 427
 428         status = dbwrap_traverse_read(ctx->db, g_lock_locks_fn, &state, &count);
 429         if (!NT_STATUS_IS_OK(status)) {
 430                 return -1;
 431         } else {
 432                 return count;
 433         }
 434 }
 435
 436 NTSTATUS g_lock_dump(struct g_lock_ctx *ctx, const char *name,
 437                      int (*fn)(struct server_id pid,
 438                                enum g_lock_type lock_type,
 439                                void *private_data),
 440                      void *private_data)
 441 {
 442         TDB_DATA data;
 443         unsigned i, num_locks;
 444         struct g_lock_rec *locks = NULL;
 445         bool ret;
 446         NTSTATUS status;
 447
 448         status = dbwrap_fetch_bystring(ctx->db, talloc_tos(), name, &data);
 449         if (!NT_STATUS_IS_OK(status)) {
 450                 return status;
 451         }
 452
 453         if ((data.dsize == 0) || (data.dptr == NULL)) {
 454                 return NT_STATUS_OK;
 455         }
 456
 457         ret = g_lock_parse(talloc_tos(), data, &num_locks, &locks);
 458
 459         TALLOC_FREE(data.dptr);
 460
 461         if (!ret) {
 462                 DEBUG(10, ("g_lock_parse for %s failed\n", name));
 463                 return NT_STATUS_INTERNAL_ERROR;
 464         }
 465
 466         for (i=0; i<num_locks; i++) {
 467                 if (fn(locks[i].pid, locks[i].lock_type, private_data) != 0) {
 468                         break;
 469                 }
 470         }
 471         TALLOC_FREE(locks);
 472         return NT_STATUS_OK;
 473 }
 474
 475 struct g_lock_get_state {
 476         bool found;
 477         struct server_id *pid;
 478 };
 479
 480 static int g_lock_get_fn(struct server_id pid, enum g_lock_type lock_type,
 481                          void *priv)
 482 {
 483         struct g_lock_get_state *state = (struct g_lock_get_state *)priv;
 484         state->found = true;
 485         *state->pid = pid;
 486         return 1;
 487 }
 488
 489 NTSTATUS g_lock_get(struct g_lock_ctx *ctx, const char *name,
 490                     struct server_id *pid)
 491 {
 492         struct g_lock_get_state state;
 493         NTSTATUS status;
 494
 495         state.found = false;
 496         state.pid = pid;
 497
 498         status = g_lock_dump(ctx, name, g_lock_get_fn, &state);
 499         if (!NT_STATUS_IS_OK(status)) {
 500                 return status;
 501         }
 502         if (!state.found) {
 503                 return NT_STATUS_NOT_FOUND;
 504         }
 505         return NT_STATUS_OK;
 506 }
 507
 508 static bool g_lock_init_all(TALLOC_CTX *mem_ctx,
 509                             struct tevent_context **pev,
 510                             struct messaging_context **pmsg,
 511                             struct g_lock_ctx **pg_ctx)
 512 {
 513         struct tevent_context *ev = NULL;
 514         struct messaging_context *msg = NULL;
 515         struct g_lock_ctx *g_ctx = NULL;
 516
 517         ev = samba_tevent_context_init(mem_ctx);
 518         if (ev == NULL) {
 519                 d_fprintf(stderr, "ERROR: could not init event context\n");
 520                 goto fail;
 521         }
 522         msg = messaging_init(mem_ctx, ev);
 523         if (msg == NULL) {
 524                 d_fprintf(stderr, "ERROR: could not init messaging context\n");
 525                 goto fail;
 526         }
 527         g_ctx = g_lock_ctx_init(mem_ctx, msg);
 528         if (g_ctx == NULL) {
 529                 d_fprintf(stderr, "ERROR: could not init g_lock context\n");
 530                 goto fail;
 531         }
 532
 533         *pev = ev;
 534         *pmsg = msg;
 535         *pg_ctx = g_ctx;
 536         return true;
 537 fail:
 538         TALLOC_FREE(g_ctx);
 539         TALLOC_FREE(msg);
 540         TALLOC_FREE(ev);
 541         return false;
 542 }
 543
 544 NTSTATUS g_lock_do(const char *name, enum g_lock_type lock_type,
 545                    struct timeval timeout,
 546                    void (*fn)(void *private_data), void *private_data)
 547 {
 548         struct tevent_context *ev = NULL;
 549         struct messaging_context *msg = NULL;
 550         struct g_lock_ctx *g_ctx = NULL;
 551         NTSTATUS status;
 552
 553         if (!g_lock_init_all(talloc_tos(), &ev, &msg, &g_ctx)) {
 554                 status = NT_STATUS_ACCESS_DENIED;
 555                 goto done;
 556         }
 557
 558         status = g_lock_lock(g_ctx, name, lock_type, timeout);
 559         if (!NT_STATUS_IS_OK(status)) {
 560                 goto done;
 561         }
 562         fn(private_data);
 563         g_lock_unlock(g_ctx, name);
 564
 565 done:
 566         TALLOC_FREE(g_ctx);
 567         TALLOC_FREE(msg);
 568         TALLOC_FREE(ev);
 569         return status;
 570 }