source/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 /****************************************************************************
 166  Delete a record if it is for a dead process, if check_self is true, then
 167  delete any records belonging to this pid also (there shouldn't be any).
 168 ****************************************************************************/
 169
 170 static int delete_fn(TDB_CONTEXT *ttdb, TDB_DATA kbuf, TDB_DATA dbuf, void *state)
 171 {
 172         struct lock_struct *locks;
 173         int count, i;
 174         BOOL check_self = *(BOOL *)state;
 175         pid_t mypid = sys_getpid();
 176
 177         tdb_chainlock(tdb, kbuf);
 178
 179         locks = (struct lock_struct *)dbuf.dptr;
 180
 181         count = dbuf.dsize / sizeof(*locks);
 182         for (i=0; i<count; i++) {
 183                 struct lock_struct *lock = &locks[i];
 184
 185                 /* If check_self is true we want to remove our own records. */
 186                 if (check_self && (mypid == lock->context.pid)) {
 187
 188                         DEBUG(0,("brlock : delete_fn. LOGIC ERROR ! Shutting down and a record for my pid (%u) exists !\n",
 189                                         (unsigned int)lock->context.pid ));
 190
 191                 } else if (process_exists(lock->context.pid)) {
 192
 193                         DEBUG(10,("brlock : delete_fn. pid %u exists.\n", (unsigned int)lock->context.pid ));
 194                         continue;
 195                 }
 196
 197                 DEBUG(10,("brlock : delete_fn. Deleting record for process %u\n",
 198                                 (unsigned int)lock->context.pid ));
 199
 200                 if (count > 1 && i < count-1) {
 201                         memmove(&locks[i], &locks[i+1],
 202                                 sizeof(*locks)*((count-1) - i));
 203                 }
 204                 count--;
 205                 i--;
 206         }
 207
 208         if (count == 0) {
 209                 tdb_delete(tdb, kbuf);
 210         } else if (count < (dbuf.dsize / sizeof(*locks))) {
 211                 dbuf.dsize = count * sizeof(*locks);
 212                 tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
 213         }
 214
 215         tdb_chainunlock(tdb, kbuf);
 216         return 0;
 217 }
 218
 219 /****************************************************************************
 220  Open up the brlock.tdb database.
 221 ****************************************************************************/
 222
 223 void brl_init(int read_only)
 224 {
 225         BOOL check_self = False;
 226
 227         if (tdb)
 228                 return;
 229         tdb = tdb_open_log(lock_path("brlock.tdb"), 0,  TDB_DEFAULT|(read_only?0x0:TDB_CLEAR_IF_FIRST),
 230                        read_only?O_RDONLY:(O_RDWR|O_CREAT), 0644);
 231         if (!tdb) {
 232                 DEBUG(0,("Failed to open byte range locking database\n"));
 233                 return;
 234         }
 235
 236         /* delete any dead locks */
 237         if (!read_only)
 238                 tdb_traverse(tdb, delete_fn, &check_self);
 239 }
 240
 241 /****************************************************************************
 242  Close down the brlock.tdb database.
 243 ****************************************************************************/
 244
 245 void brl_shutdown(int read_only)
 246 {
 247         BOOL check_self = True;
 248
 249         if (!tdb)
 250                 return;
 251
 252         /* delete any dead locks */
 253         if (!read_only)
 254                 tdb_traverse(tdb, delete_fn, &check_self);
 255
 256         tdb_close(tdb);
 257 }
 258
 259 #if ZERO_ZERO
 260 /****************************************************************************
 261 compare two locks for sorting
 262 ****************************************************************************/
 263 static int lock_compare(struct lock_struct *lck1,
 264                          struct lock_struct *lck2)
 265 {
 266         if (lck1->start != lck2->start) return (lck1->start - lck2->start);
 267         if (lck2->size != lck1->size) {
 268                 return ((int)lck1->size - (int)lck2->size);
 269         }
 270         return 0;
 271 }
 272 #endif
 273
 274 /****************************************************************************
 275  Lock a range of bytes.
 276 ****************************************************************************/
 277
 278 NTSTATUS brl_lock(SMB_DEV_T dev, SMB_INO_T ino, int fnum,
 279                   uint16 smbpid, pid_t pid, uint16 tid,
 280                   br_off start, br_off size,
 281                   enum brl_type lock_type)
 282 {
 283         TDB_DATA kbuf, dbuf;
 284         int count, i;
 285         struct lock_struct lock, *locks;
 286         char *tp;
 287         NTSTATUS status = NT_STATUS_OK;
 288         static int last_failed = -1;
 289         static br_off last_failed_start;
 290
 291         kbuf = locking_key(dev,ino);
 292
 293         dbuf.dptr = NULL;
 294
 295 #if !ZERO_ZERO
 296         if (start == 0 && size == 0) {
 297                 DEBUG(0,("client sent 0/0 lock - please report this\n"));
 298         }
 299 #endif
 300
 301         tdb_chainlock(tdb, kbuf);
 302         dbuf = tdb_fetch(tdb, kbuf);
 303
 304         lock.context.smbpid = smbpid;
 305         lock.context.pid = pid;
 306         lock.context.tid = tid;
 307         lock.start = start;
 308         lock.size = size;
 309         lock.fnum = fnum;
 310         lock.lock_type = lock_type;
 311
 312         if (dbuf.dptr) {
 313                 /* there are existing locks - make sure they don't conflict */
 314                 locks = (struct lock_struct *)dbuf.dptr;
 315                 count = dbuf.dsize / sizeof(*locks);
 316                 for (i=0; i<count; i++) {
 317                         if (brl_conflict(&locks[i], &lock)) {
 318                                 status = NT_STATUS_LOCK_NOT_GRANTED;
 319                                 goto fail;
 320                         }
 321 #if ZERO_ZERO
 322                         if (lock.start == 0 && lock.size == 0 &&
 323                             locks[i].size == 0) {
 324                                 break;
 325                         }
 326 #endif
 327                 }
 328         }
 329
 330         /* no conflicts - add it to the list of locks */
 331         tp = Realloc(dbuf.dptr, dbuf.dsize + sizeof(*locks));
 332         if (!tp) {
 333                 status = NT_STATUS_NO_MEMORY;
 334                 goto fail;
 335         } else {
 336                 dbuf.dptr = tp;
 337         }
 338         memcpy(dbuf.dptr + dbuf.dsize, &lock, sizeof(lock));
 339         dbuf.dsize += sizeof(lock);
 340
 341 #if ZERO_ZERO
 342         /* sort the lock list */
 343         qsort(dbuf.dptr, dbuf.dsize/sizeof(lock), sizeof(lock), lock_compare);
 344 #endif
 345
 346         tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
 347
 348         SAFE_FREE(dbuf.dptr);
 349         tdb_chainunlock(tdb, kbuf);
 350         return NT_STATUS_OK;
 351
 352  fail:
 353         /* this is a nasty hack to try to simulate the lock result cache code in w2k.
 354            It isn't completely accurate as I haven't yet worked out the correct
 355            semantics (tridge)
 356         */
 357         if (last_failed == fnum &&
 358             last_failed_start == start &&
 359             NT_STATUS_EQUAL(status, NT_STATUS_LOCK_NOT_GRANTED)) {
 360                 status = NT_STATUS_FILE_LOCK_CONFLICT;
 361         }
 362         last_failed = fnum;
 363         last_failed_start = start;
 364
 365         SAFE_FREE(dbuf.dptr);
 366         tdb_chainunlock(tdb, kbuf);
 367         return status;
 368 }
 369
 370 /****************************************************************************
 371  Unlock a range of bytes.
 372 ****************************************************************************/
 373
 374 BOOL brl_unlock(SMB_DEV_T dev, SMB_INO_T ino, int fnum,
 375                 uint16 smbpid, pid_t pid, uint16 tid,
 376                 br_off start, br_off size)
 377 {
 378         TDB_DATA kbuf, dbuf;
 379         int count, i;
 380         struct lock_struct *locks;
 381         struct lock_context context;
 382
 383         kbuf = locking_key(dev,ino);
 384
 385         dbuf.dptr = NULL;
 386
 387         tdb_chainlock(tdb, kbuf);
 388         dbuf = tdb_fetch(tdb, kbuf);
 389
 390         if (!dbuf.dptr) {
 391                 DEBUG(10,("brl_unlock: tdb_fetch failed !\n"));
 392                 goto fail;
 393         }
 394
 395         context.smbpid = smbpid;
 396         context.pid = pid;
 397         context.tid = tid;
 398
 399         /* there are existing locks - find a match */
 400         locks = (struct lock_struct *)dbuf.dptr;
 401         count = dbuf.dsize / sizeof(*locks);
 402
 403 #if ZERO_ZERO
 404         for (i=0; i<count; i++) {
 405                 struct lock_struct *lock = &locks[i];
 406
 407                 if (lock->lock_type == WRITE_LOCK &&
 408                     brl_same_context(&lock->context, &context) &&
 409                     lock->fnum == fnum &&
 410                     lock->start == start &&
 411                     lock->size == size) {
 412                         /* found it - delete it */
 413                         if (count == 1) {
 414                                 tdb_delete(tdb, kbuf);
 415                         } else {
 416                                 if (i < count-1) {
 417                                         memmove(&locks[i], &locks[i+1],
 418                                                 sizeof(*locks)*((count-1) - i));
 419                                 }
 420                                 dbuf.dsize -= sizeof(*locks);
 421                                 tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
 422                         }
 423
 424                         SAFE_FREE(dbuf.dptr);
 425                         tdb_chainunlock(tdb, kbuf);
 426                         return True;
 427                 }
 428         }
 429 #endif
 430
 431         locks = (struct lock_struct *)dbuf.dptr;
 432         count = dbuf.dsize / sizeof(*locks);
 433         for (i=0; i<count; i++) {
 434                 struct lock_struct *lock = &locks[i];
 435
 436                 if (brl_same_context(&lock->context, &context) &&
 437                     lock->fnum == fnum &&
 438                     lock->start == start &&
 439                     lock->size == size) {
 440                         /* found it - delete it */
 441                         if (count == 1) {
 442                                 tdb_delete(tdb, kbuf);
 443                         } else {
 444                                 if (i < count-1) {
 445                                         memmove(&locks[i], &locks[i+1],
 446                                                 sizeof(*locks)*((count-1) - i));
 447                                 }
 448                                 dbuf.dsize -= sizeof(*locks);
 449                                 tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
 450                         }
 451
 452                         SAFE_FREE(dbuf.dptr);
 453                         tdb_chainunlock(tdb, kbuf);
 454                         return True;
 455                 }
 456         }
 457
 458         /* we didn't find it */
 459
 460  fail:
 461         SAFE_FREE(dbuf.dptr);
 462         tdb_chainunlock(tdb, kbuf);
 463         return False;
 464 }
 465
 466
 467 /****************************************************************************
 468  Test if we could add a lock if we wanted to.
 469 ****************************************************************************/
 470
 471 BOOL brl_locktest(SMB_DEV_T dev, SMB_INO_T ino, int fnum,
 472                   uint16 smbpid, pid_t pid, uint16 tid,
 473                   br_off start, br_off size,
 474                   enum brl_type lock_type, int check_self)
 475 {
 476         TDB_DATA kbuf, dbuf;
 477         int count, i;
 478         struct lock_struct lock, *locks;
 479
 480         kbuf = locking_key(dev,ino);
 481
 482         dbuf.dptr = NULL;
 483
 484         tdb_chainlock(tdb, kbuf);
 485         dbuf = tdb_fetch(tdb, kbuf);
 486
 487         lock.context.smbpid = smbpid;
 488         lock.context.pid = pid;
 489         lock.context.tid = tid;
 490         lock.start = start;
 491         lock.size = size;
 492         lock.fnum = fnum;
 493         lock.lock_type = lock_type;
 494
 495         if (dbuf.dptr) {
 496                 /* there are existing locks - make sure they don't conflict */
 497                 locks = (struct lock_struct *)dbuf.dptr;
 498                 count = dbuf.dsize / sizeof(*locks);
 499                 for (i=0; i<count; i++) {
 500                         if (check_self) {
 501                                 if (brl_conflict(&locks[i], &lock))
 502                                         goto fail;
 503                         } else {
 504                                 /*
 505                                  * Our own locks don't conflict.
 506                                  */
 507                                 if (brl_conflict_other(&locks[i], &lock))
 508                                         goto fail;
 509                         }
 510                 }
 511         }
 512
 513         /* no conflicts - we could have added it */
 514         SAFE_FREE(dbuf.dptr);
 515         tdb_chainunlock(tdb, kbuf);
 516         return True;
 517
 518  fail:
 519         SAFE_FREE(dbuf.dptr);
 520         tdb_chainunlock(tdb, kbuf);
 521         return False;
 522 }
 523
 524 /****************************************************************************
 525  Remove any locks associated with a open file.
 526 ****************************************************************************/
 527
 528 void brl_close(SMB_DEV_T dev, SMB_INO_T ino, pid_t pid, int tid, int fnum)
 529 {
 530         TDB_DATA kbuf, dbuf;
 531         int count, i, dcount=0;
 532         struct lock_struct *locks;
 533
 534         kbuf = locking_key(dev,ino);
 535
 536         dbuf.dptr = NULL;
 537
 538         tdb_chainlock(tdb, kbuf);
 539         dbuf = tdb_fetch(tdb, kbuf);
 540
 541         if (!dbuf.dptr) goto fail;
 542
 543         /* there are existing locks - remove any for this fnum */
 544         locks = (struct lock_struct *)dbuf.dptr;
 545         count = dbuf.dsize / sizeof(*locks);
 546         for (i=0; i<count; i++) {
 547                 struct lock_struct *lock = &locks[i];
 548
 549                 if (lock->context.tid == tid &&
 550                     lock->context.pid == pid &&
 551                     lock->fnum == fnum) {
 552                         /* found it - delete it */
 553                         if (count > 1 && i < count-1) {
 554                                 memmove(&locks[i], &locks[i+1],
 555                                         sizeof(*locks)*((count-1) - i));
 556                         }
 557                         count--;
 558                         i--;
 559                         dcount++;
 560                 }
 561         }
 562
 563         if (count == 0) {
 564                 tdb_delete(tdb, kbuf);
 565         } else if (count < (dbuf.dsize / sizeof(*locks))) {
 566                 dbuf.dsize -= dcount * sizeof(*locks);
 567                 tdb_store(tdb, kbuf, dbuf, TDB_REPLACE);
 568         }
 569
 570         /* we didn't find it */
 571  fail:
 572         SAFE_FREE(dbuf.dptr);
 573         tdb_chainunlock(tdb, kbuf);
 574 }
 575
 576 /****************************************************************************
 577  Traverse the whole database with this function, calling traverse_callback
 578  on each lock.
 579 ****************************************************************************/
 580
 581 static int traverse_fn(TDB_CONTEXT *ttdb, TDB_DATA kbuf, TDB_DATA dbuf, void *state)
 582 {
 583         struct lock_struct *locks;
 584         struct lock_key *key;
 585         int i;
 586
 587         BRLOCK_FN(traverse_callback) = (BRLOCK_FN_CAST())state;
 588
 589         locks = (struct lock_struct *)dbuf.dptr;
 590         key = (struct lock_key *)kbuf.dptr;
 591
 592         for (i=0;i<dbuf.dsize/sizeof(*locks);i++) {
 593                 traverse_callback(key->device, key->inode,
 594                                   locks[i].context.pid,
 595                                   locks[i].lock_type,
 596                                   locks[i].start,
 597                                   locks[i].size);
 598         }
 599         return 0;
 600 }
 601
 602 /*******************************************************************
 603  Call the specified function on each lock in the database.
 604 ********************************************************************/
 605
 606 int brl_forall(BRLOCK_FN(fn))
 607 {
 608         if (!tdb) return 0;
 609         return tdb_traverse(tdb, traverse_fn, (void *)fn);
 610 }