source/smbd/blocking.c

   1 /*
   2    Unix SMB/CIFS implementation.
   3    Blocking Locking functions
   4    Copyright (C) Jeremy Allison 1998
   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 2 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, write to the Free Software
  18    Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19 */
  20
  21 #include "includes.h"
  22
  23 extern char *OutBuffer;
  24
  25 /****************************************************************************
  26  This is the structure to queue to implement blocking locks.
  27  notify. It consists of the requesting SMB and the expiry time.
  28 *****************************************************************************/
  29
  30 typedef struct {
  31   ubi_slNode msg_next;
  32   int com_type;
  33   files_struct *fsp;
  34   time_t expire_time;
  35   int lock_num;
  36   char *inbuf;
  37   int length;
  38 } blocking_lock_record;
  39
  40 static ubi_slList blocking_lock_queue = { NULL, (ubi_slNodePtr)&blocking_lock_queue, 0};
  41
  42 /****************************************************************************
  43  Destructor for the above structure.
  44 ****************************************************************************/
  45
  46 static void free_blocking_lock_record(blocking_lock_record *blr)
  47 {
  48   SAFE_FREE(blr->inbuf);
  49   SAFE_FREE(blr);
  50 }
  51
  52 /****************************************************************************
  53  Get the files_struct given a particular queued SMB.
  54 *****************************************************************************/
  55
  56 static files_struct *get_fsp_from_pkt(char *inbuf)
  57 {
  58   switch(CVAL(inbuf,smb_com)) {
  59   case SMBlock:
  60   case SMBlockread:
  61     return file_fsp(inbuf,smb_vwv0);
  62   case SMBlockingX:
  63     return file_fsp(inbuf,smb_vwv2);
  64   default:
  65     DEBUG(0,("get_fsp_from_pkt: PANIC - unknown type on blocking lock queue - exiting.!\n"));
  66     exit_server("PANIC - unknown type on blocking lock queue");
  67   }
  68   return NULL; /* Keep compiler happy. */
  69 }
  70
  71 /****************************************************************************
  72  Determine if this is a secondary element of a chained SMB.
  73   **************************************************************************/
  74
  75 static BOOL in_chained_smb(void)
  76 {
  77   return (chain_size != 0);
  78 }
  79
  80 /****************************************************************************
  81  Function to push a blocking lock request onto the lock queue.
  82 ****************************************************************************/
  83
  84 BOOL push_blocking_lock_request( char *inbuf, int length, int lock_timeout, int lock_num)
  85 {
  86   blocking_lock_record *blr;
  87
  88   if(in_chained_smb() ) {
  89     DEBUG(0,("push_blocking_lock_request: cannot queue a chained request (currently).\n"));
  90     return False;
  91   }
  92
  93   /*
  94    * Now queue an entry on the blocking lock queue. We setup
  95    * the expiration time here.
  96    */
  97
  98   if((blr = (blocking_lock_record *)malloc(sizeof(blocking_lock_record))) == NULL) {
  99     DEBUG(0,("push_blocking_lock_request: Malloc fail !\n" ));
 100     return False;
 101   }
 102
 103   if((blr->inbuf = (char *)malloc(length)) == NULL) {
 104     DEBUG(0,("push_blocking_lock_request: Malloc fail (2)!\n" ));
 105     SAFE_FREE(blr);
 106     return False;
 107   }
 108
 109   blr->com_type = CVAL(inbuf,smb_com);
 110   blr->fsp = get_fsp_from_pkt(inbuf);
 111   blr->expire_time = (lock_timeout == -1) ? (time_t)-1 : time(NULL) + (time_t)lock_timeout;
 112   blr->lock_num = lock_num;
 113   memcpy(blr->inbuf, inbuf, length);
 114   blr->length = length;
 115
 116   ubi_slAddTail(&blocking_lock_queue, blr);
 117
 118
 119   DEBUG(3,("push_blocking_lock_request: lock request length=%d blocked with expiry time %d (+%d) \
 120 for fnum = %d, name = %s\n", length, (int)blr->expire_time, lock_timeout,
 121         blr->fsp->fnum, blr->fsp->fsp_name ));
 122
 123   return True;
 124 }
 125
 126 /****************************************************************************
 127  Return a smd with a given size.
 128 *****************************************************************************/
 129
 130 static void send_blocking_reply(char *outbuf, int outsize)
 131 {
 132         if(outsize > 4)
 133                 smb_setlen(outbuf,outsize - 4);
 134
 135         if (!send_smb(smbd_server_fd(),outbuf))
 136                 exit_server("send_blocking_reply: send_smb failed.");
 137 }
 138
 139 /****************************************************************************
 140  Return a lockingX success SMB.
 141 *****************************************************************************/
 142
 143 static void reply_lockingX_success(blocking_lock_record *blr)
 144 {
 145   char *outbuf = OutBuffer;
 146   int bufsize = BUFFER_SIZE;
 147   char *inbuf = blr->inbuf;
 148   int outsize = 0;
 149
 150   construct_reply_common(inbuf, outbuf);
 151   set_message(outbuf,2,0,True);
 152
 153   /*
 154    * As this message is a lockingX call we must handle
 155    * any following chained message correctly.
 156    * This is normally handled in construct_reply(),
 157    * but as that calls switch_message, we can't use
 158    * that here and must set up the chain info manually.
 159    */
 160
 161   outsize = chain_reply(inbuf,outbuf,blr->length,bufsize);
 162
 163   outsize += chain_size;
 164
 165   send_blocking_reply(outbuf,outsize);
 166 }
 167
 168 /****************************************************************************
 169  Return a generic lock fail error blocking call.
 170 *****************************************************************************/
 171
 172 static void generic_blocking_lock_error(blocking_lock_record *blr, NTSTATUS status)
 173 {
 174         char *outbuf = OutBuffer;
 175         char *inbuf = blr->inbuf;
 176         construct_reply_common(inbuf, outbuf);
 177
 178         /* whenever a timeout is given w2k maps LOCK_NOT_GRANTED to
 179            FILE_LOCK_CONFLICT! (tridge) */
 180         if (NT_STATUS_EQUAL(status, NT_STATUS_LOCK_NOT_GRANTED)) {
 181                 status = NT_STATUS_FILE_LOCK_CONFLICT;
 182         }
 183
 184         ERROR_NT(status);
 185         if (!send_smb(smbd_server_fd(),outbuf))
 186                 exit_server("generic_blocking_lock_error: send_smb failed.");
 187 }
 188
 189 /****************************************************************************
 190  Return a lock fail error for a lockingX call. Undo all the locks we have
 191  obtained first.
 192 *****************************************************************************/
 193
 194 static void reply_lockingX_error(blocking_lock_record *blr, NTSTATUS status)
 195 {
 196         char *inbuf = blr->inbuf;
 197         files_struct *fsp = blr->fsp;
 198         connection_struct *conn = conn_find(SVAL(inbuf,smb_tid));
 199         uint16 num_ulocks = SVAL(inbuf,smb_vwv6);
 200         SMB_BIG_UINT count = (SMB_BIG_UINT)0, offset = (SMB_BIG_UINT) 0;
 201         uint16 lock_pid;
 202         unsigned char locktype = CVAL(inbuf,smb_vwv3);
 203         BOOL large_file_format = (locktype & LOCKING_ANDX_LARGE_FILES);
 204         char *data;
 205         int i;
 206
 207         data = smb_buf(inbuf) + ((large_file_format ? 20 : 10)*num_ulocks);
 208
 209         /*
 210          * Data now points at the beginning of the list
 211          * of smb_lkrng structs.
 212          */
 213
 214         /*
 215          * Ensure we don't do a remove on the lock that just failed,
 216          * as under POSIX rules, if we have a lock already there, we
 217          * will delete it (and we shouldn't) .....
 218          */
 219
 220         for(i = blr->lock_num - 1; i >= 0; i--) {
 221                 BOOL err;
 222
 223                 lock_pid = get_lock_pid( data, i, large_file_format);
 224                 count = get_lock_count( data, i, large_file_format);
 225                 offset = get_lock_offset( data, i, large_file_format, &err);
 226
 227                 /*
 228                  * We know err cannot be set as if it was the lock
 229                  * request would never have been queued. JRA.
 230                  */
 231
 232                 do_unlock(fsp,conn,lock_pid,count,offset);
 233         }
 234
 235         generic_blocking_lock_error(blr, status);
 236 }
 237
 238 /****************************************************************************
 239  Return a lock fail error.
 240 *****************************************************************************/
 241
 242 static void blocking_lock_reply_error(blocking_lock_record *blr, NTSTATUS status)
 243 {
 244         switch(blr->com_type) {
 245         case SMBlock:
 246         case SMBlockread:
 247                 generic_blocking_lock_error(blr, status);
 248                 break;
 249         case SMBlockingX:
 250                 reply_lockingX_error(blr, status);
 251                 break;
 252         default:
 253                 DEBUG(0,("blocking_lock_reply_error: PANIC - unknown type on blocking lock queue - exiting.!\n"));
 254                 exit_server("PANIC - unknown type on blocking lock queue");
 255         }
 256 }
 257
 258 /****************************************************************************
 259  Attempt to finish off getting all pending blocking locks for a lockread call.
 260  Returns True if we want to be removed from the list.
 261 *****************************************************************************/
 262
 263 static BOOL process_lockread(blocking_lock_record *blr)
 264 {
 265         char *outbuf = OutBuffer;
 266         char *inbuf = blr->inbuf;
 267         ssize_t nread = -1;
 268         char *data, *p;
 269         int outsize = 0;
 270         SMB_OFF_T startpos;
 271         size_t numtoread;
 272         NTSTATUS status;
 273         connection_struct *conn = conn_find(SVAL(inbuf,smb_tid));
 274         files_struct *fsp = blr->fsp;
 275
 276         numtoread = SVAL(inbuf,smb_vwv1);
 277         startpos = IVAL(inbuf,smb_vwv2);
 278
 279         numtoread = MIN(BUFFER_SIZE-outsize,numtoread);
 280         data = smb_buf(outbuf) + 3;
 281
 282         status = do_lock_spin( fsp, conn, SVAL(inbuf,smb_pid), (SMB_BIG_UINT)numtoread,
 283                           (SMB_BIG_UINT)startpos, READ_LOCK);
 284         if (NT_STATUS_V(status)) {
 285                 if ((errno != EACCES) && (errno != EAGAIN)) {
 286                         /*
 287                          * We have other than a "can't get lock" POSIX
 288                          * error. Send an error.
 289                          * Return True so we get dequeued.
 290                          */
 291                         generic_blocking_lock_error(blr, status);
 292                         return True;
 293                 }
 294
 295                 /*
 296                  * Still waiting for lock....
 297                  */
 298
 299                 DEBUG(10,("process_lockread: failed to get lock for file = %s. Still waiting....\n",
 300                           fsp->fsp_name));
 301                 return False;
 302         }
 303
 304         nread = read_file(fsp,data,startpos,numtoread);
 305
 306         if (nread < 0) {
 307                 generic_blocking_lock_error(blr,NT_STATUS_ACCESS_DENIED);
 308                 return True;
 309         }
 310
 311         construct_reply_common(inbuf, outbuf);
 312         outsize = set_message(outbuf,5,0,True);
 313
 314         outsize += nread;
 315         SSVAL(outbuf,smb_vwv0,nread);
 316         SSVAL(outbuf,smb_vwv5,nread+3);
 317         p = smb_buf(outbuf);
 318         *p++ = 1;
 319         SSVAL(p,0,nread); p += 2;
 320         set_message_end(outbuf, p+nread);
 321
 322         DEBUG(3, ( "process_lockread file = %s, fnum=%d num=%d nread=%d\n",
 323                    fsp->fsp_name, fsp->fnum, (int)numtoread, (int)nread ) );
 324
 325         send_blocking_reply(outbuf,outsize);
 326         return True;
 327 }
 328
 329 /****************************************************************************
 330  Attempt to finish off getting all pending blocking locks for a lock call.
 331  Returns True if we want to be removed from the list.
 332 *****************************************************************************/
 333
 334 static BOOL process_lock(blocking_lock_record *blr)
 335 {
 336         char *outbuf = OutBuffer;
 337         char *inbuf = blr->inbuf;
 338         int outsize;
 339         SMB_OFF_T count = 0, offset = 0;
 340         NTSTATUS status;
 341         connection_struct *conn = conn_find(SVAL(inbuf,smb_tid));
 342         files_struct *fsp = blr->fsp;
 343
 344         count = IVAL(inbuf,smb_vwv1);
 345         offset = IVAL(inbuf,smb_vwv3);
 346
 347         errno = 0;
 348         status = do_lock_spin(fsp, conn, SVAL(inbuf,smb_pid), (SMB_BIG_UINT)count,
 349                          (SMB_BIG_UINT)offset, WRITE_LOCK);
 350         if (NT_STATUS_IS_ERR(status)) {
 351                 if((errno != EACCES) && (errno != EAGAIN)) {
 352                         /*
 353                          * We have other than a "can't get lock" POSIX
 354                          * error. Send an error.
 355                          * Return True so we get dequeued.
 356                          */
 357
 358                         blocking_lock_reply_error(blr, status);
 359                         return True;
 360                 }
 361                 /*
 362                  * Still can't get the lock - keep waiting.
 363                  */
 364                 DEBUG(10,("process_lock: failed to get lock for file = %s. Still waiting....\n",
 365                           fsp->fsp_name));
 366                 return False;
 367         }
 368
 369         /*
 370          * Success - we got the lock.
 371          */
 372
 373         DEBUG(3,("process_lock : file=%s fnum=%d offset=%.0f count=%.0f\n",
 374                  fsp->fsp_name, fsp->fnum, (double)offset, (double)count));
 375
 376         construct_reply_common(inbuf, outbuf);
 377         outsize = set_message(outbuf,0,0,True);
 378         send_blocking_reply(outbuf,outsize);
 379         return True;
 380 }
 381
 382 /****************************************************************************
 383  Attempt to finish off getting all pending blocking locks for a lockingX call.
 384  Returns True if we want to be removed from the list.
 385 *****************************************************************************/
 386
 387 static BOOL process_lockingX(blocking_lock_record *blr)
 388 {
 389         char *inbuf = blr->inbuf;
 390         unsigned char locktype = CVAL(inbuf,smb_vwv3);
 391         files_struct *fsp = blr->fsp;
 392         connection_struct *conn = conn_find(SVAL(inbuf,smb_tid));
 393         uint16 num_ulocks = SVAL(inbuf,smb_vwv6);
 394         uint16 num_locks = SVAL(inbuf,smb_vwv7);
 395         SMB_BIG_UINT count = (SMB_BIG_UINT)0, offset = (SMB_BIG_UINT)0;
 396         uint16 lock_pid;
 397         BOOL large_file_format = (locktype & LOCKING_ANDX_LARGE_FILES);
 398         char *data;
 399         NTSTATUS status = NT_STATUS_OK;
 400
 401         data = smb_buf(inbuf) + ((large_file_format ? 20 : 10)*num_ulocks);
 402
 403         /*
 404          * Data now points at the beginning of the list
 405          * of smb_lkrng structs.
 406          */
 407
 408         for(; blr->lock_num < num_locks; blr->lock_num++) {
 409                 BOOL err;
 410
 411                 lock_pid = get_lock_pid( data, blr->lock_num, large_file_format);
 412                 count = get_lock_count( data, blr->lock_num, large_file_format);
 413                 offset = get_lock_offset( data, blr->lock_num, large_file_format, &err);
 414
 415                 /*
 416                  * We know err cannot be set as if it was the lock
 417                  * request would never have been queued. JRA.
 418                  */
 419                 errno = 0;
 420                 status = do_lock_spin(fsp,conn,lock_pid,count,offset,
 421                                  ((locktype & 1) ? READ_LOCK : WRITE_LOCK));
 422                 if (NT_STATUS_IS_ERR(status)) break;
 423         }
 424
 425         if(blr->lock_num == num_locks) {
 426                 /*
 427                  * Success - we got all the locks.
 428                  */
 429
 430                 DEBUG(3,("process_lockingX file = %s, fnum=%d type=%d num_locks=%d\n",
 431                          fsp->fsp_name, fsp->fnum, (unsigned int)locktype, num_locks) );
 432
 433                 reply_lockingX_success(blr);
 434                 return True;
 435         } else if ((errno != EACCES) && (errno != EAGAIN)) {
 436                 /*
 437                  * We have other than a "can't get lock" POSIX
 438                  * error. Free any locks we had and return an error.
 439                  * Return True so we get dequeued.
 440                  */
 441
 442                 blocking_lock_reply_error(blr, status);
 443                 return True;
 444         }
 445
 446         /*
 447          * Still can't get all the locks - keep waiting.
 448          */
 449
 450         DEBUG(10,("process_lockingX: only got %d locks of %d needed for file %s, fnum = %d. \
 451 Waiting....\n",
 452                   blr->lock_num, num_locks, fsp->fsp_name, fsp->fnum));
 453
 454         return False;
 455 }
 456
 457 /****************************************************************************
 458  Process a blocking lock SMB.
 459  Returns True if we want to be removed from the list.
 460 *****************************************************************************/
 461
 462 static BOOL blocking_lock_record_process(blocking_lock_record *blr)
 463 {
 464   switch(blr->com_type) {
 465   case SMBlock:
 466     return process_lock(blr);
 467   case SMBlockread:
 468     return process_lockread(blr);
 469   case SMBlockingX:
 470     return process_lockingX(blr);
 471   default:
 472     DEBUG(0,("blocking_lock_record_process: PANIC - unknown type on blocking lock queue - exiting.!\n"));
 473     exit_server("PANIC - unknown type on blocking lock queue");
 474   }
 475   return False; /* Keep compiler happy. */
 476 }
 477
 478 /****************************************************************************
 479  Delete entries by fnum from the blocking lock pending queue.
 480 *****************************************************************************/
 481
 482 void remove_pending_lock_requests_by_fid(files_struct *fsp)
 483 {
 484   blocking_lock_record *blr = (blocking_lock_record *)ubi_slFirst( &blocking_lock_queue );
 485   blocking_lock_record *prev = NULL;
 486
 487   while(blr != NULL) {
 488     if(blr->fsp->fnum == fsp->fnum) {
 489
 490       DEBUG(10,("remove_pending_lock_requests_by_fid - removing request type %d for \
 491 file %s fnum = %d\n", blr->com_type, fsp->fsp_name, fsp->fnum ));
 492
 493       free_blocking_lock_record((blocking_lock_record *)ubi_slRemNext( &blocking_lock_queue, prev));
 494       blr = (blocking_lock_record *)(prev ? ubi_slNext(prev) : ubi_slFirst(&blocking_lock_queue));
 495       continue;
 496     }
 497
 498     prev = blr;
 499     blr = (blocking_lock_record *)ubi_slNext(blr);
 500   }
 501 }
 502
 503 /****************************************************************************
 504  Delete entries by mid from the blocking lock pending queue. Always send reply.
 505 *****************************************************************************/
 506
 507 void remove_pending_lock_requests_by_mid(int mid)
 508 {
 509   blocking_lock_record *blr = (blocking_lock_record *)ubi_slFirst( &blocking_lock_queue );
 510   blocking_lock_record *prev = NULL;
 511
 512   while(blr != NULL) {
 513     if(SVAL(blr->inbuf,smb_mid) == mid) {
 514       files_struct *fsp = blr->fsp;
 515
 516       DEBUG(10,("remove_pending_lock_requests_by_mid - removing request type %d for \
 517 file %s fnum = %d\n", blr->com_type, fsp->fsp_name, fsp->fnum ));
 518
 519       blocking_lock_reply_error(blr,NT_STATUS_CANCELLED);
 520       free_blocking_lock_record((blocking_lock_record *)ubi_slRemNext( &blocking_lock_queue, prev));
 521       blr = (blocking_lock_record *)(prev ? ubi_slNext(prev) : ubi_slFirst(&blocking_lock_queue));
 522       continue;
 523     }
 524
 525     prev = blr;
 526     blr = (blocking_lock_record *)ubi_slNext(blr);
 527   }
 528 }
 529
 530 /****************************************************************************
 531  Return True if the blocking lock queue has entries.
 532 *****************************************************************************/
 533
 534 BOOL blocking_locks_pending(void)
 535 {
 536   blocking_lock_record *blr = (blocking_lock_record *)ubi_slFirst( &blocking_lock_queue );
 537   return (blr == NULL ? False : True);
 538 }
 539
 540 /****************************************************************************
 541  Process the blocking lock queue. Note that this is only called as root.
 542 *****************************************************************************/
 543
 544 void process_blocking_lock_queue(time_t t)
 545 {
 546   blocking_lock_record *blr = (blocking_lock_record *)ubi_slFirst( &blocking_lock_queue );
 547   blocking_lock_record *prev = NULL;
 548
 549   if(blr == NULL)
 550     return;
 551
 552   /*
 553    * Go through the queue and see if we can get any of the locks.
 554    */
 555
 556   while(blr != NULL) {
 557     connection_struct *conn = NULL;
 558     uint16 vuid;
 559     files_struct *fsp = NULL;
 560
 561     /*
 562      * Ensure we don't have any old chain_fsp values
 563      * sitting around....
 564      */
 565     chain_size = 0;
 566     file_chain_reset();
 567     fsp = blr->fsp;
 568
 569     conn = conn_find(SVAL(blr->inbuf,smb_tid));
 570     vuid = (lp_security() == SEC_SHARE) ? UID_FIELD_INVALID :
 571                   SVAL(blr->inbuf,smb_uid);
 572
 573     DEBUG(5,("process_blocking_lock_queue: examining pending lock fnum = %d for file %s\n",
 574           fsp->fnum, fsp->fsp_name ));
 575
 576     if((blr->expire_time != -1) && (blr->expire_time > t)) {
 577       /*
 578        * Lock expired - throw away all previously
 579        * obtained locks and return lock error.
 580        */
 581       DEBUG(5,("process_blocking_lock_queue: pending lock fnum = %d for file %s timed out.\n",
 582           fsp->fnum, fsp->fsp_name ));
 583
 584       blocking_lock_reply_error(blr,NT_STATUS_ACCESS_DENIED);
 585       free_blocking_lock_record((blocking_lock_record *)ubi_slRemNext( &blocking_lock_queue, prev));
 586       blr = (blocking_lock_record *)(prev ? ubi_slNext(prev) : ubi_slFirst(&blocking_lock_queue));
 587       continue;
 588     }
 589
 590     if(!change_to_user(conn,vuid)) {
 591       DEBUG(0,("process_blocking_lock_queue: Unable to become user vuid=%d.\n",
 592             vuid ));
 593       /*
 594        * Remove the entry and return an error to the client.
 595        */
 596       blocking_lock_reply_error(blr,NT_STATUS_ACCESS_DENIED);
 597       free_blocking_lock_record((blocking_lock_record *)ubi_slRemNext( &blocking_lock_queue, prev));
 598       blr = (blocking_lock_record *)(prev ? ubi_slNext(prev) : ubi_slFirst(&blocking_lock_queue));
 599       continue;
 600     }
 601
 602     if(!set_current_service(conn,True)) {
 603       DEBUG(0,("process_blocking_lock_queue: Unable to become service Error was %s.\n", strerror(errno) ));
 604       /*
 605        * Remove the entry and return an error to the client.
 606        */
 607       blocking_lock_reply_error(blr,NT_STATUS_ACCESS_DENIED);
 608       free_blocking_lock_record((blocking_lock_record *)ubi_slRemNext( &blocking_lock_queue, prev));
 609       blr = (blocking_lock_record *)(prev ? ubi_slNext(prev) : ubi_slFirst(&blocking_lock_queue));
 610       change_to_root_user();
 611       continue;
 612     }
 613
 614     /*
 615      * Go through the remaining locks and try and obtain them.
 616      * The call returns True if all locks were obtained successfully
 617      * and False if we still need to wait.
 618      */
 619
 620     if(blocking_lock_record_process(blr)) {
 621       free_blocking_lock_record((blocking_lock_record *)ubi_slRemNext( &blocking_lock_queue, prev));
 622       blr = (blocking_lock_record *)(prev ? ubi_slNext(prev) : ubi_slFirst(&blocking_lock_queue));
 623       change_to_root_user();
 624       continue;
 625     }
 626
 627     change_to_root_user();
 628
 629     /*
 630      * Move to the next in the list.
 631      */
 632     prev = blr;
 633     blr = (blocking_lock_record *)ubi_slNext(blr);
 634   }
 635 }