source3/locking/brlock.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    byte range locking code
   4    Updated to handle range splits/merges.
   5
   6    Copyright (C) Andrew Tridgell 1992-2000
   7    Copyright (C) Jeremy Allison 1992-2000
   8
   9    This program is free software; you can redistribute it and/or modify
  10    it under the terms of the GNU General Public License as published by
  11    the Free Software Foundation; either version 2 of the License, or
  12    (at your option) any later version.
  13
  14    This program is distributed in the hope that it will be useful,
  15    but WITHOUT ANY WARRANTY; without even the implied warranty of
  16    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  17    GNU General Public License for more details.
  18
  19    You should have received a copy of the GNU General Public License
  20    along with this program; if not, write to the Free Software
  21    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  22 */
  23
  24 /* This module implements a tdb based byte range locking service,
  25    replacing the fcntl() based byte range locking previously
  26    used. This allows us to provide the same semantics as NT */
  27
  28 #include "includes.h"
  29
  30 #define ZERO_ZERO 0
  31
  32 /* This contains elements that differentiate locks. The smbpid is a
  33    client supplied pid, and is essentially the locking context for
  34    this client */
  35
  36 struct lock_context {
  37         uint16 smbpid;
  38         uint16 tid;
  39         pid_t pid;
  40 };
  41
  42 /* The data in brlock records is an unsorted linear array of these
  43    records.  It is unnecessary to store the count as tdb provides the
  44    size of the record */
  45
  46 struct lock_struct {
  47         struct lock_context context;
  48         br_off start;
  49         br_off size;
  50         int fnum;
  51         enum brl_type lock_type;
  52 };
  53
  54 /* The key used in the brlock database. */
  55
  56 struct lock_key {
  57         SMB_DEV_T device;
  58         SMB_INO_T inode;
  59 };
  60
  61 /* The open brlock.tdb database. */
  62
  63 static TDB_CONTEXT *tdb;
  64
  65 /****************************************************************************
  66  Create a locking key - ensuring zero filled for pad purposes.
  67 ****************************************************************************/
  68
  69 static TDB_DATA locking_key(SMB_DEV_T dev, SMB_INO_T inode)
  70 {
  71         static struct lock_key key;
  72         TDB_DATA kbuf;
  73
  74         memset(&key, '\0', sizeof(key));
  75         key.device = dev;
  76         key.inode = inode;
  77         kbuf.dptr = (char *)&key;
  78         kbuf.dsize = sizeof(key);
  79         return kbuf;
  80 }
  81
  82 /****************************************************************************
  83  See if two locking contexts are equal.
  84 ****************************************************************************/
  85
  86 static BOOL brl_same_context(struct lock_context *ctx1,
  87                              struct lock_context *ctx2)
  88 {
  89         return (ctx1->pid == ctx2->pid) &&
  90                 (ctx1->smbpid == ctx2->smbpid) &&
  91                 (ctx1->tid == ctx2->tid);
  92 }
  93
  94 /****************************************************************************
  95  See if lock2 can be added when lock1 is in place.
  96 ****************************************************************************/
  97
  98 static BOOL brl_conflict(struct lock_struct *lck1,
  99                          struct lock_struct *lck2)
 100 {
 101         if (lck1->lock_type == READ_LOCK && lck2->lock_type == READ_LOCK) {
 102                 return False;
 103         }
 104
 105         if (brl_same_context(&lck1->context, &lck2->context) &&
 106             lck2->lock_type == READ_LOCK && lck1->fnum == lck2->fnum) {
 107                 return False;
 108         }
 109
 110         if (lck1->start >= (lck2->start + lck2->size) ||
 111             lck2->start >= (lck1->start + lck1->size)) {
 112                 return False;
 113         }
 114
 115         return True;
 116 }
 117
 118 #if ZERO_ZERO
 119 static BOOL brl_conflict1(struct lock_struct *lck1,
 120                          struct lock_struct *lck2)
 121 {
 122         if (lck1->lock_type == READ_LOCK && lck2->lock_type == READ_LOCK) {
 123                 return False;
 124         }
 125
 126         if (brl_same_context(&lck1->context, &lck2->context) &&
 127             lck2->lock_type == READ_LOCK && lck1->fnum == lck2->fnum) {
 128                 return False;
 129         }
 130
 131         if (lck2->start == 0 && lck2->size == 0 && lck1->size != 0) {
 132                 return True;
 133         }
 134
 135         if (lck1->start >= (lck2->start + lck2->size) ||
 136             lck2->start >= (lck1->start + lck1->size)) {
 137                 return False;
 138         }
 139
 140         return True;
 141 }
 142 #endif
 143
 144 /****************************************************************************
 145  Check to see if this lock conflicts, but ignore our own locks on the
 146  same fnum only.
 147 ****************************************************************************/
 148
 149 static BOOL brl_conflict_other(struct lock_struct *lck1, struct lock_struct *lck2)
 150 {
 151         if (lck1->lock_type == READ_LOCK && lck2->lock_type == READ_LOCK)
 152                 return False;
 153
 154         if (brl_same_context(&lck1->context, &lck2->context) &&
 155                                 lck1->fnum == lck2->fnum)
 156                 return False;
 157
 158         if (lck1->start >= (lck2->start + lck2->size) ||
 159             lck2->start >= (lck1->start + lck1->size)) return False;
 160
 161         return True;
 162 }
 163
 164
 165 #if DONT_DO_THIS
 166         /* doing this traversal could kill solaris machines under high load (tridge) */
 167         /* delete any dead locks */
 168
 169 /****************************************************************************
 170  Delete a record if it is for a dead process, if check_self is true, then
 171  delete any records belonging to this pid also (there shouldn't be any).
 172 ****************************************************************************/
 173
 174 static int delete_fn(TDB_CONTEXT *ttdb, TDB_DATA kbuf, TDB_DATA dbuf, void *state)
 175 {
 176         struct lock_struct *locks;
 177         int count, i;
 178         BOOL check_self = *(BOOL *)state;
 179         pid_t mypid = sys_getpid();
 180
 181         tdb_chainlock(tdb, kbuf);
 182
 183         locks = (struct lock_struct *)dbuf.dptr;
 184
 185         count = dbuf.dsize / sizeof(*locks);
 186         for (i=0; i<count; i++) {
 187                 struct lock_struct *lock = &locks[i];
 188
 189                 /* If check_self is true we want to remove our own records. */
 190                 if (check_self && (mypid == lock->context.pid)) {
 191
 192                         DEBUG(0,("brlock : delete_fn. LOGIC ERROR ! Shutting down and a record for my pid (%u) exists !\n",
 193                                         (unsigned int)lock->context.pid ));
 194
 195                 } else if (process_exists(lock->context.pid)) {
 196
 197                         DEBUG(10,("brlock : delete_fn. pid %u exists.\n", (unsigned int)lock->context.pid ));
 198                         continue;
 199                 }
 200
 201                 DEBUG(10,("brlock : delete_fn. Deleting record for process %u\n",
 202                                 (unsigned int)lock->context.pid ));
 203
 204                 if (count > 1 && i < count-1) {
 205                         memmove(&locks[i], &locks[i+1],
 206                                 sizeof(*locks)*((count-1) - i));
 207                 }
 208                 count--;
 209                 i--;
 210         }
 211
 212         if (count == 0) {
 213                 tdb_delete(tdb, kbuf);
 214         } else if (count < (dbuf.dsize / sizeof(*locks))) {
 215                 dbuf.dsize = count * sizeof(*locks);
 216                 tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
 217         }
 218
 219         tdb_chainunlock(tdb, kbuf);
 220         return 0;
 221 }
 222 #endif
 223
 224 /****************************************************************************
 225  Open up the brlock.tdb database.
 226 ****************************************************************************/
 227
 228 void brl_init(int read_only)
 229 {
 230         if (tdb)
 231                 return;
 232         tdb = tdb_open_log(lock_path("brlock.tdb"), 0,  TDB_DEFAULT|(read_only?0x0:TDB_CLEAR_IF_FIRST),
 233                        read_only?O_RDONLY:(O_RDWR|O_CREAT), 0644);
 234         if (!tdb) {
 235                 DEBUG(0,("Failed to open byte range locking database\n"));
 236                 return;
 237         }
 238
 239 #if DONT_DO_THIS
 240         /* doing this traversal could kill solaris machines under high load (tridge) */
 241         /* delete any dead locks */
 242         if (!read_only) {
 243                 BOOL check_self = False;
 244                 tdb_traverse(tdb, delete_fn, &check_self);
 245         }
 246 #endif
 247 }
 248
 249 /****************************************************************************
 250  Close down the brlock.tdb database.
 251 ****************************************************************************/
 252
 253 void brl_shutdown(int read_only)
 254 {
 255         if (!tdb)
 256                 return;
 257
 258 #if DONT_DO_THIS
 259         /* doing this traversal could kill solaris machines under high load (tridge) */
 260         /* delete any dead locks */
 261         if (!read_only) {
 262                 BOOL check_self = True;
 263                 tdb_traverse(tdb, delete_fn, &check_self);
 264         }
 265 #endif
 266
 267         tdb_close(tdb);
 268 }
 269
 270 #if ZERO_ZERO
 271 /****************************************************************************
 272 compare two locks for sorting
 273 ****************************************************************************/
 274 static int lock_compare(struct lock_struct *lck1,
 275                          struct lock_struct *lck2)
 276 {
 277         if (lck1->start != lck2->start) return (lck1->start - lck2->start);
 278         if (lck2->size != lck1->size) {
 279                 return ((int)lck1->size - (int)lck2->size);
 280         }
 281         return 0;
 282 }
 283 #endif
 284
 285 /****************************************************************************
 286  Lock a range of bytes.
 287 ****************************************************************************/
 288
 289 NTSTATUS brl_lock(SMB_DEV_T dev, SMB_INO_T ino, int fnum,
 290                   uint16 smbpid, pid_t pid, uint16 tid,
 291                   br_off start, br_off size,
 292                   enum brl_type lock_type)
 293 {
 294         TDB_DATA kbuf, dbuf;
 295         int count, i;
 296         struct lock_struct lock, *locks;
 297         char *tp;
 298         NTSTATUS status = NT_STATUS_OK;
 299         static int last_failed = -1;
 300         static br_off last_failed_start;
 301
 302         kbuf = locking_key(dev,ino);
 303
 304         dbuf.dptr = NULL;
 305
 306 #if !ZERO_ZERO
 307         if (start == 0 && size == 0) {
 308                 DEBUG(0,("client sent 0/0 lock - please report this\n"));
 309         }
 310 #endif
 311
 312         tdb_chainlock(tdb, kbuf);
 313         dbuf = tdb_fetch(tdb, kbuf);
 314
 315         lock.context.smbpid = smbpid;
 316         lock.context.pid = pid;
 317         lock.context.tid = tid;
 318         lock.start = start;
 319         lock.size = size;
 320         lock.fnum = fnum;
 321         lock.lock_type = lock_type;
 322
 323         if (dbuf.dptr) {
 324                 /* there are existing locks - make sure they don't conflict */
 325                 locks = (struct lock_struct *)dbuf.dptr;
 326                 count = dbuf.dsize / sizeof(*locks);
 327                 for (i=0; i<count; i++) {
 328                         if (brl_conflict(&locks[i], &lock)) {
 329                                 status = NT_STATUS_LOCK_NOT_GRANTED;
 330                                 goto fail;
 331                         }
 332 #if ZERO_ZERO
 333                         if (lock.start == 0 && lock.size == 0 &&
 334                             locks[i].size == 0) {
 335                                 break;
 336                         }
 337 #endif
 338                 }
 339         }
 340
 341         /* no conflicts - add it to the list of locks */
 342         tp = Realloc(dbuf.dptr, dbuf.dsize + sizeof(*locks));
 343         if (!tp) {
 344                 status = NT_STATUS_NO_MEMORY;
 345                 goto fail;
 346         } else {
 347                 dbuf.dptr = tp;
 348         }
 349         memcpy(dbuf.dptr + dbuf.dsize, &lock, sizeof(lock));
 350         dbuf.dsize += sizeof(lock);
 351
 352 #if ZERO_ZERO
 353         /* sort the lock list */
 354         qsort(dbuf.dptr, dbuf.dsize/sizeof(lock), sizeof(lock), lock_compare);
 355 #endif
 356
 357         tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
 358
 359         SAFE_FREE(dbuf.dptr);
 360         tdb_chainunlock(tdb, kbuf);
 361         return NT_STATUS_OK;
 362
 363  fail:
 364         /* this is a nasty hack to try to simulate the lock result cache code in w2k.
 365            It isn't completely accurate as I haven't yet worked out the correct
 366            semantics (tridge)
 367         */
 368         if (last_failed == fnum &&
 369             last_failed_start == start &&
 370             NT_STATUS_EQUAL(status, NT_STATUS_LOCK_NOT_GRANTED)) {
 371                 status = NT_STATUS_FILE_LOCK_CONFLICT;
 372         }
 373         last_failed = fnum;
 374         last_failed_start = start;
 375
 376         SAFE_FREE(dbuf.dptr);
 377         tdb_chainunlock(tdb, kbuf);
 378         return status;
 379 }
 380
 381 /****************************************************************************
 382  Unlock a range of bytes.
 383 ****************************************************************************/
 384
 385 BOOL brl_unlock(SMB_DEV_T dev, SMB_INO_T ino, int fnum,
 386                 uint16 smbpid, pid_t pid, uint16 tid,
 387                 br_off start, br_off size)
 388 {
 389         TDB_DATA kbuf, dbuf;
 390         int count, i;
 391         struct lock_struct *locks;
 392         struct lock_context context;
 393
 394         kbuf = locking_key(dev,ino);
 395
 396         dbuf.dptr = NULL;
 397
 398         tdb_chainlock(tdb, kbuf);
 399         dbuf = tdb_fetch(tdb, kbuf);
 400
 401         if (!dbuf.dptr) {
 402                 DEBUG(10,("brl_unlock: tdb_fetch failed !\n"));
 403                 goto fail;
 404         }
 405
 406         context.smbpid = smbpid;
 407         context.pid = pid;
 408         context.tid = tid;
 409
 410         /* there are existing locks - find a match */
 411         locks = (struct lock_struct *)dbuf.dptr;
 412         count = dbuf.dsize / sizeof(*locks);
 413
 414 #if ZERO_ZERO
 415         for (i=0; i<count; i++) {
 416                 struct lock_struct *lock = &locks[i];
 417
 418                 if (lock->lock_type == WRITE_LOCK &&
 419                     brl_same_context(&lock->context, &context) &&
 420                     lock->fnum == fnum &&
 421                     lock->start == start &&
 422                     lock->size == size) {
 423                         /* found it - delete it */
 424                         if (count == 1) {
 425                                 tdb_delete(tdb, kbuf);
 426                         } else {
 427                                 if (i < count-1) {
 428                                         memmove(&locks[i], &locks[i+1],
 429                                                 sizeof(*locks)*((count-1) - i));
 430                                 }
 431                                 dbuf.dsize -= sizeof(*locks);
 432                                 tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
 433                         }
 434
 435                         SAFE_FREE(dbuf.dptr);
 436                         tdb_chainunlock(tdb, kbuf);
 437                         return True;
 438                 }
 439         }
 440 #endif
 441
 442         locks = (struct lock_struct *)dbuf.dptr;
 443         count = dbuf.dsize / sizeof(*locks);
 444         for (i=0; i<count; i++) {
 445                 struct lock_struct *lock = &locks[i];
 446
 447                 if (brl_same_context(&lock->context, &context) &&
 448                     lock->fnum == fnum &&
 449                     lock->start == start &&
 450                     lock->size == size) {
 451                         /* found it - delete it */
 452                         if (count == 1) {
 453                                 tdb_delete(tdb, kbuf);
 454                         } else {
 455                                 if (i < count-1) {
 456                                         memmove(&locks[i], &locks[i+1],
 457                                                 sizeof(*locks)*((count-1) - i));
 458                                 }
 459                                 dbuf.dsize -= sizeof(*locks);
 460                                 tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
 461                         }
 462
 463                         SAFE_FREE(dbuf.dptr);
 464                         tdb_chainunlock(tdb, kbuf);
 465                         return True;
 466                 }
 467         }
 468
 469         /* we didn't find it */
 470
 471  fail:
 472         SAFE_FREE(dbuf.dptr);
 473         tdb_chainunlock(tdb, kbuf);
 474         return False;
 475 }
 476
 477
 478 /****************************************************************************
 479  Test if we could add a lock if we wanted to.
 480 ****************************************************************************/
 481
 482 BOOL brl_locktest(SMB_DEV_T dev, SMB_INO_T ino, int fnum,
 483                   uint16 smbpid, pid_t pid, uint16 tid,
 484                   br_off start, br_off size,
 485                   enum brl_type lock_type, int check_self)
 486 {
 487         TDB_DATA kbuf, dbuf;
 488         int count, i;
 489         struct lock_struct lock, *locks;
 490
 491         kbuf = locking_key(dev,ino);
 492
 493         dbuf.dptr = NULL;
 494
 495         tdb_chainlock(tdb, kbuf);
 496         dbuf = tdb_fetch(tdb, kbuf);
 497
 498         lock.context.smbpid = smbpid;
 499         lock.context.pid = pid;
 500         lock.context.tid = tid;
 501         lock.start = start;
 502         lock.size = size;
 503         lock.fnum = fnum;
 504         lock.lock_type = lock_type;
 505
 506         if (dbuf.dptr) {
 507                 /* there are existing locks - make sure they don't conflict */
 508                 locks = (struct lock_struct *)dbuf.dptr;
 509                 count = dbuf.dsize / sizeof(*locks);
 510                 for (i=0; i<count; i++) {
 511                         if (check_self) {
 512                                 if (brl_conflict(&locks[i], &lock))
 513                                         goto fail;
 514                         } else {
 515                                 /*
 516                                  * Our own locks don't conflict.
 517                                  */
 518                                 if (brl_conflict_other(&locks[i], &lock))
 519                                         goto fail;
 520                         }
 521                 }
 522         }
 523
 524         /* no conflicts - we could have added it */
 525         SAFE_FREE(dbuf.dptr);
 526         tdb_chainunlock(tdb, kbuf);
 527         return True;
 528
 529  fail:
 530         SAFE_FREE(dbuf.dptr);
 531         tdb_chainunlock(tdb, kbuf);
 532         return False;
 533 }
 534
 535 /****************************************************************************
 536  Remove any locks associated with a open file.
 537 ****************************************************************************/
 538
 539 void brl_close(SMB_DEV_T dev, SMB_INO_T ino, pid_t pid, int tid, int fnum)
 540 {
 541         TDB_DATA kbuf, dbuf;
 542         int count, i, dcount=0;
 543         struct lock_struct *locks;
 544
 545         kbuf = locking_key(dev,ino);
 546
 547         dbuf.dptr = NULL;
 548
 549         tdb_chainlock(tdb, kbuf);
 550         dbuf = tdb_fetch(tdb, kbuf);
 551
 552         if (!dbuf.dptr) goto fail;
 553
 554         /* there are existing locks - remove any for this fnum */
 555         locks = (struct lock_struct *)dbuf.dptr;
 556         count = dbuf.dsize / sizeof(*locks);
 557         for (i=0; i<count; i++) {
 558                 struct lock_struct *lock = &locks[i];
 559
 560                 if (lock->context.tid == tid &&
 561                     lock->context.pid == pid &&
 562                     lock->fnum == fnum) {
 563                         /* found it - delete it */
 564                         if (count > 1 && i < count-1) {
 565                                 memmove(&locks[i], &locks[i+1],
 566                                         sizeof(*locks)*((count-1) - i));
 567                         }
 568                         count--;
 569                         i--;
 570                         dcount++;
 571                 }
 572         }
 573
 574         if (count == 0) {
 575                 tdb_delete(tdb, kbuf);
 576         } else if (count < (dbuf.dsize / sizeof(*locks))) {
 577                 dbuf.dsize -= dcount * sizeof(*locks);
 578                 tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
 579         }
 580
 581         /* we didn't find it */
 582  fail:
 583         SAFE_FREE(dbuf.dptr);
 584         tdb_chainunlock(tdb, kbuf);
 585 }
 586
 587 /****************************************************************************
 588  Traverse the whole database with this function, calling traverse_callback
 589  on each lock.
 590 ****************************************************************************/
 591
 592 static int traverse_fn(TDB_CONTEXT *ttdb, TDB_DATA kbuf, TDB_DATA dbuf, void *state)
 593 {
 594         struct lock_struct *locks;
 595         struct lock_key *key;
 596         int i;
 597
 598         BRLOCK_FN(traverse_callback) = (BRLOCK_FN_CAST())state;
 599
 600         locks = (struct lock_struct *)dbuf.dptr;
 601         key = (struct lock_key *)kbuf.dptr;
 602
 603         for (i=0;i<dbuf.dsize/sizeof(*locks);i++) {
 604                 traverse_callback(key->device, key->inode,
 605                                   locks[i].context.pid,
 606                                   locks[i].lock_type,
 607                                   locks[i].start,
 608                                   locks[i].size);
 609         }
 610         return 0;
 611 }
 612
 613 /*******************************************************************
 614  Call the specified function on each lock in the database.
 615 ********************************************************************/
 616
 617 int brl_forall(BRLOCK_FN(fn))
 618 {
 619         if (!tdb) return 0;
 620         return tdb_traverse(tdb, traverse_fn, (void *)fn);
 621 }