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