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 (procid_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         tevent_req_set_callback(subreq, g_lock_lock_retry, req);
 231         return req;
 232 }
 233
 234 static void g_lock_lock_retry(struct tevent_req *subreq)
 235 {
 236         struct tevent_req *req = tevent_req_callback_data(
 237                 subreq, struct tevent_req);
 238         struct g_lock_lock_state *state = tevent_req_data(
 239                 req, struct g_lock_lock_state);
 240         struct server_id self = messaging_server_id(state->ctx->msg);
 241         struct db_record *rec;
 242         NTSTATUS status;
 243
 244         status = dbwrap_record_watch_recv(subreq, talloc_tos(), &rec);
 245         TALLOC_FREE(subreq);
 246         if (tevent_req_nterror(req, status)) {
 247                 return;
 248         }
 249         status = g_lock_trylock(rec, self, state->type);
 250         if (NT_STATUS_IS_OK(status)) {
 251                 TALLOC_FREE(rec);
 252                 tevent_req_done(req);
 253                 return;
 254         }
 255         if (!NT_STATUS_EQUAL(status, NT_STATUS_LOCK_NOT_GRANTED)) {
 256                 TALLOC_FREE(rec);
 257                 tevent_req_nterror(req, status);
 258                 return;
 259         }
 260         subreq = dbwrap_record_watch_send(state, state->ev, rec,
 261                                           state->ctx->msg);
 262         if (tevent_req_nomem(subreq, req)) {
 263                 return;
 264         }
 265         tevent_req_set_callback(subreq, g_lock_lock_retry, req);
 266         return;
 267
 268 }
 269
 270 NTSTATUS g_lock_lock_recv(struct tevent_req *req)
 271 {
 272         return tevent_req_simple_recv_ntstatus(req);
 273 }
 274
 275 NTSTATUS g_lock_lock(struct g_lock_ctx *ctx, const char *name,
 276                      enum g_lock_type type, struct timeval timeout)
 277 {
 278         TALLOC_CTX *frame = talloc_stackframe();
 279         struct tevent_context *ev;
 280         struct tevent_req *req;
 281         struct timeval end;
 282         NTSTATUS status = NT_STATUS_NO_MEMORY;
 283
 284         ev = tevent_context_init(frame);
 285         if (ev == NULL) {
 286                 goto fail;
 287         }
 288         req = g_lock_lock_send(frame, ev, ctx, name, type);
 289         if (req == NULL) {
 290                 goto fail;
 291         }
 292         end = timeval_current_ofs(timeout.tv_sec, timeout.tv_usec);
 293         if (!tevent_req_set_endtime(req, ev, end)) {
 294                 goto fail;
 295         }
 296         if (!tevent_req_poll_ntstatus(req, ev, &status)) {
 297                 goto fail;
 298         }
 299         status = g_lock_lock_recv(req);
 300  fail:
 301         TALLOC_FREE(frame);
 302         return status;
 303 }
 304
 305 NTSTATUS g_lock_unlock(struct g_lock_ctx *ctx, const char *name)
 306 {
 307         struct server_id self = messaging_server_id(ctx->msg);
 308         struct db_record *rec = NULL;
 309         struct g_lock_rec *locks = NULL;
 310         unsigned i, num_locks;
 311         NTSTATUS status;
 312         TDB_DATA value;
 313
 314         rec = dbwrap_fetch_locked(ctx->db, talloc_tos(),
 315                                   string_term_tdb_data(name));
 316         if (rec == NULL) {
 317                 DEBUG(10, ("fetch_locked(\"%s\") failed\n", name));
 318                 status = NT_STATUS_INTERNAL_ERROR;
 319                 goto done;
 320         }
 321
 322         value = dbwrap_record_get_value(rec);
 323
 324         if (!g_lock_parse(talloc_tos(), value, &num_locks, &locks)) {
 325                 DEBUG(10, ("g_lock_parse for %s failed\n", name));
 326                 status = NT_STATUS_FILE_INVALID;
 327                 goto done;
 328         }
 329         for (i=0; i<num_locks; i++) {
 330                 if (procid_equal(&self, &locks[i].pid)) {
 331                         break;
 332                 }
 333         }
 334         if (i == num_locks) {
 335                 DEBUG(10, ("g_lock_force_unlock: Lock not found\n"));
 336                 status = NT_STATUS_NOT_FOUND;
 337                 goto done;
 338         }
 339
 340         locks[i] = locks[num_locks-1];
 341         num_locks -= 1;
 342
 343         if (num_locks == 0) {
 344                 status = dbwrap_record_delete(rec);
 345         } else {
 346                 TDB_DATA data;
 347                 data = make_tdb_data((uint8_t *)locks,
 348                                      sizeof(struct g_lock_rec) * num_locks);
 349                 status = dbwrap_record_store(rec, data, 0);
 350         }
 351         if (!NT_STATUS_IS_OK(status)) {
 352                 DEBUG(1, ("g_lock_force_unlock: Could not store record: %s\n",
 353                           nt_errstr(status)));
 354                 goto done;
 355         }
 356
 357         status = NT_STATUS_OK;
 358 done:
 359         TALLOC_FREE(rec);
 360         TALLOC_FREE(locks);
 361         return status;
 362 }
 363
 364 struct g_lock_locks_state {
 365         int (*fn)(const char *name, void *private_data);
 366         void *private_data;
 367 };
 368
 369 static int g_lock_locks_fn(struct db_record *rec, void *priv)
 370 {
 371         TDB_DATA key;
 372         struct g_lock_locks_state *state = (struct g_lock_locks_state *)priv;
 373
 374         key = dbwrap_record_get_key(rec);
 375         if ((key.dsize == 0) || (key.dptr[key.dsize-1] != 0)) {
 376                 DEBUG(1, ("invalid key in g_lock.tdb, ignoring\n"));
 377                 return 0;
 378         }
 379         return state->fn((char *)key.dptr, state->private_data);
 380 }
 381
 382 int g_lock_locks(struct g_lock_ctx *ctx,
 383                  int (*fn)(const char *name, void *private_data),
 384                  void *private_data)
 385 {
 386         struct g_lock_locks_state state;
 387         NTSTATUS status;
 388         int count;
 389
 390         state.fn = fn;
 391         state.private_data = private_data;
 392
 393         status = dbwrap_traverse_read(ctx->db, g_lock_locks_fn, &state, &count);
 394         if (!NT_STATUS_IS_OK(status)) {
 395                 return -1;
 396         } else {
 397                 return count;
 398         }
 399 }
 400
 401 NTSTATUS g_lock_dump(struct g_lock_ctx *ctx, const char *name,
 402                      int (*fn)(struct server_id pid,
 403                                enum g_lock_type lock_type,
 404                                void *private_data),
 405                      void *private_data)
 406 {
 407         TDB_DATA data;
 408         unsigned i, num_locks;
 409         struct g_lock_rec *locks = NULL;
 410         bool ret;
 411         NTSTATUS status;
 412
 413         status = dbwrap_fetch_bystring(ctx->db, talloc_tos(), name, &data);
 414         if (!NT_STATUS_IS_OK(status)) {
 415                 return status;
 416         }
 417
 418         if ((data.dsize == 0) || (data.dptr == NULL)) {
 419                 return NT_STATUS_OK;
 420         }
 421
 422         ret = g_lock_parse(talloc_tos(), data, &num_locks, &locks);
 423
 424         TALLOC_FREE(data.dptr);
 425
 426         if (!ret) {
 427                 DEBUG(10, ("g_lock_parse for %s failed\n", name));
 428                 return NT_STATUS_INTERNAL_ERROR;
 429         }
 430
 431         for (i=0; i<num_locks; i++) {
 432                 if (fn(locks[i].pid, locks[i].lock_type, private_data) != 0) {
 433                         break;
 434                 }
 435         }
 436         TALLOC_FREE(locks);
 437         return NT_STATUS_OK;
 438 }
 439
 440 struct g_lock_get_state {
 441         bool found;
 442         struct server_id *pid;
 443 };
 444
 445 static int g_lock_get_fn(struct server_id pid, enum g_lock_type lock_type,
 446                          void *priv)
 447 {
 448         struct g_lock_get_state *state = (struct g_lock_get_state *)priv;
 449         state->found = true;
 450         *state->pid = pid;
 451         return 1;
 452 }
 453
 454 NTSTATUS g_lock_get(struct g_lock_ctx *ctx, const char *name,
 455                     struct server_id *pid)
 456 {
 457         struct g_lock_get_state state;
 458         NTSTATUS status;
 459
 460         state.found = false;
 461         state.pid = pid;
 462
 463         status = g_lock_dump(ctx, name, g_lock_get_fn, &state);
 464         if (!NT_STATUS_IS_OK(status)) {
 465                 return status;
 466         }
 467         if (!state.found) {
 468                 return NT_STATUS_NOT_FOUND;
 469         }
 470         return NT_STATUS_OK;
 471 }
 472
 473 static bool g_lock_init_all(TALLOC_CTX *mem_ctx,
 474                             struct tevent_context **pev,
 475                             struct messaging_context **pmsg,
 476                             struct g_lock_ctx **pg_ctx)
 477 {
 478         struct tevent_context *ev = NULL;
 479         struct messaging_context *msg = NULL;
 480         struct g_lock_ctx *g_ctx = NULL;
 481
 482         ev = tevent_context_init(mem_ctx);
 483         if (ev == NULL) {
 484                 d_fprintf(stderr, "ERROR: could not init event context\n");
 485                 goto fail;
 486         }
 487         msg = messaging_init(mem_ctx, ev);
 488         if (msg == NULL) {
 489                 d_fprintf(stderr, "ERROR: could not init messaging context\n");
 490                 goto fail;
 491         }
 492         g_ctx = g_lock_ctx_init(mem_ctx, msg);
 493         if (g_ctx == NULL) {
 494                 d_fprintf(stderr, "ERROR: could not init g_lock context\n");
 495                 goto fail;
 496         }
 497
 498         *pev = ev;
 499         *pmsg = msg;
 500         *pg_ctx = g_ctx;
 501         return true;
 502 fail:
 503         TALLOC_FREE(g_ctx);
 504         TALLOC_FREE(msg);
 505         TALLOC_FREE(ev);
 506         return false;
 507 }
 508
 509 NTSTATUS g_lock_do(const char *name, enum g_lock_type lock_type,
 510                    struct timeval timeout,
 511                    void (*fn)(void *private_data), void *private_data)
 512 {
 513         struct tevent_context *ev = NULL;
 514         struct messaging_context *msg = NULL;
 515         struct g_lock_ctx *g_ctx = NULL;
 516         NTSTATUS status;
 517
 518         if (!g_lock_init_all(talloc_tos(), &ev, &msg, &g_ctx)) {
 519                 status = NT_STATUS_ACCESS_DENIED;
 520                 goto done;
 521         }
 522
 523         status = g_lock_lock(g_ctx, name, lock_type, timeout);
 524         if (!NT_STATUS_IS_OK(status)) {
 525                 goto done;
 526         }
 527         fn(private_data);
 528         g_lock_unlock(g_ctx, name);
 529
 530 done:
 531         TALLOC_FREE(g_ctx);
 532         TALLOC_FREE(msg);
 533         TALLOC_FREE(ev);
 534         return status;
 535 }