summaryrefslogtreecommitdiff
path: root/source3/locking/locking.c
blob: 9ea9e08ded4288481c321744074585945e505773 (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
/* 
   Unix SMB/Netbios implementation.
   Version 3.0
   Locking functions
   Copyright (C) Andrew Tridgell 1992-1999
   
   This program is free software; you can redistribute it and/or modify
   it under the terms of the GNU General Public License as published by
   the Free Software Foundation; either version 2 of the License, or
   (at your option) any later version.
   
   This program is distributed in the hope that it will be useful,
   but WITHOUT ANY WARRANTY; without even the implied warranty of
   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   GNU General Public License for more details.
   
   You should have received a copy of the GNU General Public License
   along with this program; if not, write to the Free Software
   Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.

   Revision History:

   12 aug 96: Erik.Devriendt@te6.siemens.be
   added support for shared memory implementation of share mode locking

   May 1997. Jeremy Allison (jallison@whistle.com). Modified share mode
   locking to deal with multiple share modes per open file.

   September 1997. Jeremy Allison (jallison@whistle.com). Added oplock
   support.

   rewrtten completely to use new tdb code. Tridge, Dec '99
*/

#include "includes.h"
extern int DEBUGLEVEL;

/* the locking database handle */
static TDB_CONTEXT *tdb;

int global_smbpid;

/****************************************************************************
 Remove any locks on this fd.
****************************************************************************/

void locking_close_file(files_struct *fsp)
{
	if (!lp_locking(SNUM(fsp->conn)))
		return;

	if(lp_posix_locking(SNUM(fsp->conn))) {
		/*
		 * We need to release all POSIX locks we have on this
		 * fd.
		 */
	}

	/*
	 * Now release all the tdb locks.
	 */

	brl_close(fsp->dev, fsp->inode, getpid(), fsp->conn->cnum, fsp->fnum);

	/*
	 * We now need to search our open file list for any other
	 * fd open on this file with outstanding POSIX locks. If we
	 * don't find one, great, just return. If we do find one then
	 * we have to add this file descriptor to the 'pending close'
	 * list of that fd, to stop the POSIX problem where the locks
	 * on *that* fd will get lost when we close this one. POSIX
	 * braindamage... JRA.
	 */

	/* Placeholder for code here.... */
}

/****************************************************************************
 Debugging aid :-).
****************************************************************************/

static const char *lock_type_name(enum brl_type lock_type)
{
	return (lock_type == READ_LOCK) ? "READ" : "WRITE";
}

/****************************************************************************
 Utility function to map a lock type correctly depending on the open
 mode of a file.
****************************************************************************/

static int map_posix_lock_type( files_struct *fsp, enum brl_type lock_type)
{
	if((lock_type == WRITE_LOCK) && !fsp->can_write) {
		/*
		 * Many UNIX's cannot get a write lock on a file opened read-only.
		 * Win32 locking semantics allow this.
		 * Do the best we can and attempt a read-only lock.
		 */
		DEBUG(10,("map_posix_lock_type: Downgrading write lock to read due to read-only file.\n"));
		return F_RDLCK;
	} else if((lock_type == READ_LOCK) && !fsp->can_read) {
		/*
		 * Ditto for read locks on write only files.
		 */
		DEBUG(10,("map_posix_lock_type: Changing read lock to write due to write-only file.\n"));
		return F_WRLCK;
	}

  /*
   * This return should be the most normal, as we attempt
   * to always open files read/write.
   */

  return (lock_type == READ_LOCK) ? F_RDLCK : F_WRLCK;
}

/****************************************************************************
 Check to see if the given unsigned lock range is within the possible POSIX
 range. Modifies the given args to be in range if possible, just returns
 False if not.
****************************************************************************/

static BOOL posix_lock_in_range(SMB_OFF_T *offset_out, SMB_OFF_T *count_out,
								SMB_BIG_UINT u_offset, SMB_BIG_UINT u_count)
{
	SMB_OFF_T offset;
	SMB_OFF_T count;

#if defined(LARGE_SMB_OFF_T) && !defined(HAVE_BROKEN_FCNTL64_LOCKS)

    SMB_OFF_T mask2 = ((SMB_OFF_T)0x4) << (SMB_OFF_T_BITS-4);
    SMB_OFF_T mask = (mask2<<1);
    SMB_OFF_T neg_mask = ~mask;

	/*
	 * In this case SMB_OFF_T is 64 bits,
	 * and the underlying system can handle 64 bit signed locks.
	 * Cast to signed type.
	 */

	offset = (SMB_OFF_T)u_offset;
	count = (SMB_OFF_T)u_count;

	/*
	 * Deal with a very common case of count of all ones.
	 * (lock entire file).
	 */

	if(count == (SMB_OFF_T)-1)
		count &= ~mask;

	/*
	 * POSIX lock ranges cannot be negative.
	 * Fail if any combination becomes negative.
	 */

	if(offset < 0 || count < 0 || (offset + count < 0)) {
		DEBUG(10,("posix_lock_in_range: negative range: offset = %.0f, count = %.0f. Ignoring lock.\n",
				(double)offset, (double)count ));
		return False;
	}

	/*
	 * In this case SMB_OFF_T is 64 bits, the offset and count
	 * fit within the positive range, and the underlying
	 * system can handle 64 bit locks. Just return as the
	 * cast values are ok.
	 */

#else /* !LARGE_SMB_OFF_T || HAVE_BROKEN_FCNTL64_LOCKS */

	/*
	 * In this case either SMB_OFF_T is 32 bits,
	 * or the underlying system cannot handle 64 bit signed locks.
	 * Either way we have to try and mangle to fit within 31 bits.
	 * This is difficult.
	 */

#if defined(HAVE_BROKEN_FCNTL64_LOCKS)

	/*
	 * SMB_OFF_T is 64 bits, but we need to use 31 bits due to
	 * broken large locking.
	 */

	/*
	 * Deal with a very common case of count of all ones.
	 * (lock entire file).
	 */

	if(u_count == (SMB_BIG_UINT)-1)
		count = 0x7FFFFFFF;

	if(((u_offset >> 32) & 0xFFFFFFFF) || ((u_count >> 32) & 0xFFFFFFFF)) {
		DEBUG(10,("posix_lock_in_range: top 32 bits not zero. offset = %.0f, count = %.0f. Ignoring lock.\n",
				(double)u_offset, (double)u_count ));
		/* Top 32 bits of offset or count were not zero. */
		return False;
	}

	/* Cast from 64 bits unsigned to 64 bits signed. */
	offset = (SMB_OFF_T)u_offset;
	count = (SMB_OFF_T)u_count;

	/*
	 * Check if we are within the 2^31 range.
	 */

	{
		int32 low_offset = (int32)offset;
		int32 low_count = (int32)count;

		if(low_offset < 0 || low_count < 0 || (low_offset + low_count < 0)) {
			DEBUG(10,("posix_lock_in_range: not within 2^31 range. low_offset = %d, low_count = %d. Ignoring lock.\n",
					low_offset, low_count ));
			return False;
		}
	}

	/*
	 * Ok - we can map from a 64 bit number to a 31 bit lock.
	 */

#else /* HAVE_BROKEN_FCNTL64_LOCKS */

	/*
	 * SMB_OFF_T is 32 bits.
	 */

#if defined(HAVE_LONGLONG)

	/*
	 * SMB_BIG_UINT is 64 bits, we can do a 32 bit shift.
	 */

	/*
	 * Deal with a very common case of count of all ones.
	 * (lock entire file).
	 */

	if(u_count == (SMB_BIG_UINT)-1)
		count = 0x7FFFFFFF;

	if(((u_offset >> 32) & 0xFFFFFFFF) || ((u_count >> 32) & 0xFFFFFFFF)) {
		DEBUG(10,("posix_lock_in_range: top 32 bits not zero. u_offset = %.0f, u_count = %.0f. Ignoring lock.\n",
				(double)u_offset, (double)u_count ));
		return False;
	}

	/* Cast from 64 bits unsigned to 32 bits signed. */
	offset = (SMB_OFF_T)u_offset;
	count = (SMB_OFF_T)u_count;

	/*
	 * Check if we are within the 2^31 range.
	 */

	if(offset < 0 || count < 0 || (offset + count < 0)) {
		DEBUG(10,("posix_lock_in_range: not within 2^31 range. offset = %d, count = %d. Ignoring lock.\n",
				(int)offset, (int)count ));
		return False;
	}

#else /* HAVE_LONGLONG */

	/*
	 * SMB_BIG_UINT and SMB_OFF_T are both 32 bits,
	 * just cast.
	 */

	/*
	 * Deal with a very common case of count of all ones.
	 * (lock entire file).
	 */

	if(u_count == (SMB_BIG_UINT)-1)
		count = 0x7FFFFFFF;

	/* Cast from 32 bits unsigned to 32 bits signed. */
	offset = (SMB_OFF_T)u_offset;
	count = (SMB_OFF_T)u_count;

	/*
	 * Check if we are within the 2^31 range.
	 */

	if(offset < 0 || count < 0 || (offset + count < 0)) {
		DEBUG(10,("posix_lock_in_range: not within 2^31 range. offset = %d, count = %d. Ignoring lock.\n",
				(int)offset, (int)count ));
		return False;
	}

#endif /* HAVE_LONGLONG */
#endif /* LARGE_SMB_OFF_T */
#endif /* !LARGE_SMB_OFF_T || HAVE_BROKEN_FCNTL64_LOCKS */

	/*
	 * The mapping was successful.
	 */

	DEBUG(10,("posix_lock_in_range: offset_out = %.0f, count_out = %.0f\n",
			(double)offset, (double)count ));

	*offset_out = offset;
	*count_out = count;
	
	return True;
}

/****************************************************************************
 POSIX function to see if a file region is locked. Returns True if the
 region is locked, False otherwise.
****************************************************************************/

static BOOL is_posix_locked(files_struct *fsp, SMB_BIG_UINT u_offset, SMB_BIG_UINT u_count, enum brl_type lock_type)
{
	SMB_OFF_T offset;
	SMB_OFF_T count;

	DEBUG(10,("is_posix_locked: File %s, offset = %.0f, count = %.0f, type = %s\n",
			fsp->fsp_name, (double)offset, (double)count, lock_type_name(lock_type) ));

	/*
	 * If the requested lock won't fit in the POSIX range, we will
	 * never set it, so presume it is not locked.
	 */

	if(!posix_lock_in_range(&offset, &count, u_offset, u_count))
		return False;

	/*
	 * Note that most UNIX's can *test* for a write lock on
	 * a read-only fd, just not *set* a write lock on a read-only
	 * fd. So we don't need to use map_lock_type here.
	 */ 

	return fcntl_lock(fsp->fd,SMB_F_GETLK,offset,count,lock_type);
}

/****************************************************************************
 POSIX function to acquire a lock. Returns True if the
 lock could be granted, False if not.
****************************************************************************/

static BOOL set_posix_lock(files_struct *fsp, SMB_BIG_UINT u_offset, SMB_BIG_UINT u_count, enum brl_type lock_type)
{
	SMB_OFF_T offset;
	SMB_OFF_T count;
	BOOL ret = True;

	DEBUG(5,("set_posix_lock: File %s, offset = %.0f, count = %.0f, type = %s\n",
			fsp->fsp_name, (double)offset, (double)count, lock_type_name(lock_type) ));

	/*
	 * If the requested lock won't fit in the POSIX range, we will
	 * pretend it was successful.
	 */

	if(!posix_lock_in_range(&offset, &count, u_offset, u_count))
		return True;

    ret = fcntl_lock(fsp->fd,SMB_F_SETLK,offset,count,map_posix_lock_type(fsp,lock_type)); 

	if(ret)
		fsp->num_posix_locks++;

	return ret;
}

/****************************************************************************
 POSIX function to release a lock. Returns True if the
 lock could be released, False if not.
****************************************************************************/

static BOOL release_posix_lock(files_struct *fsp, SMB_BIG_UINT u_offset, SMB_BIG_UINT u_count)
{
	SMB_OFF_T offset;
	SMB_OFF_T count;
	BOOL ret;

	DEBUG(5,("release_posix_lock: File %s, offset = %.0f, count = %.0f\n",
			fsp->fsp_name, (double)offset, (double)count ));

	/*
	 * If the requested lock won't fit in the POSIX range, we will
	 * pretend it was successful.
	 */

	if(!posix_lock_in_range(&offset, &count, u_offset, u_count))
		return True;

	ret = fcntl_lock(fsp->fd,SMB_F_SETLK,offset,count,F_UNLCK);

	if(ret)
		fsp->num_posix_locks--;

	return True;
}

/****************************************************************************
 Utility function called to see if a file region is locked.
****************************************************************************/

BOOL is_locked(files_struct *fsp,connection_struct *conn,
	       SMB_BIG_UINT count,SMB_BIG_UINT offset, 
	       enum brl_type lock_type)
{
	int snum = SNUM(conn);
	BOOL ret;
	
	if (count == 0)
		return(False);

	if (!lp_locking(snum) || !lp_strict_locking(snum))
		return(False);

	ret = !brl_locktest(fsp->dev, fsp->inode, 
			     global_smbpid, getpid(), conn->cnum, 
			     offset, count, lock_type);

	/*
	 * There is no lock held by an SMB daemon, check to
	 * see if there is a POSIX lock from a UNIX or NFS process.
	 * Note that as an optimisation we only bother to
	 * check this if the file is not exclusively
	 * oplocked. JRA.
	 */

	if(!ret && !EXCLUSIVE_OPLOCK_TYPE(fsp->oplock_type) && lp_posix_locking(snum))
		ret = is_posix_locked(fsp, offset, count, lock_type);

	return ret;
}

/****************************************************************************
 Utility function called by locking requests.
****************************************************************************/

BOOL do_lock(files_struct *fsp,connection_struct *conn,
             SMB_BIG_UINT count,SMB_BIG_UINT offset,enum brl_type lock_type,
             int *eclass,uint32 *ecode)
{
	BOOL ok = False;

	if (!lp_locking(SNUM(conn)))
		return(True);

	if (count == 0) {
		*eclass = ERRDOS;
		*ecode = ERRnoaccess;
		return False;
	}
	
	DEBUG(10,("do_lock: lock type %s start=%.0f len=%.0f requested for file %s\n",
		  lock_type_name(lock_type), (double)offset, (double)count, fsp->fsp_name ));

	if (OPEN_FSP(fsp) && fsp->can_lock && (fsp->conn == conn)) {
		ok = brl_lock(fsp->dev, fsp->inode, fsp->fnum,
			      global_smbpid, getpid(), conn->cnum, 
			      offset, count, 
			      lock_type);

		if(ok && lp_posix_locking(SNUM(conn))) {

			/*
			 * Try and get a POSIX lock on this range.
			 */

			ok = set_posix_lock(fsp, offset, count, lock_type);

			if(!ok) {
				/*
				 * We failed to map - we must now remove the brl
				 * lock entry.
				 */
				(void)brl_unlock(fsp->dev, fsp->inode, fsp->fnum,
								global_smbpid, getpid(), conn->cnum, 
								offset, count);
			}
		}
	}

	if (!ok) {
		*eclass = ERRDOS;
		*ecode = ERRlock;
		return False;
	}
	return True; /* Got lock */
}

/****************************************************************************
 Utility function called by unlocking requests.
****************************************************************************/

BOOL do_unlock(files_struct *fsp,connection_struct *conn,
               SMB_BIG_UINT count,SMB_BIG_UINT offset, 
	       int *eclass,uint32 *ecode)
{
	BOOL ok = False;
	
	if (!lp_locking(SNUM(conn)))
		return(True);
	
	DEBUG(10,("do_unlock: unlock start=%.0f len=%.0f requested for file %s\n",
		  (double)offset, (double)count, fsp->fsp_name ));
	
	if (OPEN_FSP(fsp) && fsp->can_lock && (fsp->conn == conn)) {
		ok = brl_unlock(fsp->dev, fsp->inode, fsp->fnum,
				global_smbpid, getpid(), conn->cnum, 
				offset, count);

		if(ok && lp_posix_locking(SNUM(conn))) {

			/*
			 * Release the POSIX lock on this range.
			 */

			(void)release_posix_lock(fsp, offset, count);
		}
	}
   
	if (!ok) {
		*eclass = ERRDOS;
		*ecode = ERRlock;
		return False;
	}
	return True; /* Did unlock */
}

/****************************************************************************
 Initialise the locking functions.
****************************************************************************/
BOOL locking_init(int read_only)
{
	brl_init(read_only);

	if (tdb) return True;

	tdb = tdb_open(lock_path("locking.tdb"), 
		       0, TDB_CLEAR_IF_FIRST, 
		       read_only?O_RDONLY:O_RDWR|O_CREAT,
		       0644);

	if (!tdb) {
		DEBUG(0,("ERROR: Failed to initialise share modes\n"));
		return False;
	}
	
	return True;
}

/*******************************************************************
 Deinitialize the share_mode management.
******************************************************************/
BOOL locking_end(void)
{
	if (tdb && tdb_close(tdb) != 0) return False;
	return True;
}

/*******************************************************************
 form a static locking key for a dev/inode pair 
******************************************************************/
static TDB_DATA locking_key(SMB_DEV_T dev, SMB_INO_T inode)
{
	static struct locking_key key;
	TDB_DATA kbuf;
	key.dev = dev;
	key.inode = inode;
	kbuf.dptr = (char *)&key;
	kbuf.dsize = sizeof(key);
	return kbuf;
}
static TDB_DATA locking_key_fsp(files_struct *fsp)
{
	return locking_key(fsp->dev, fsp->inode);
}

/*******************************************************************
 Lock a hash bucket entry.
******************************************************************/
BOOL lock_share_entry(connection_struct *conn,
		      SMB_DEV_T dev, SMB_INO_T inode)
{
	return tdb_lockchain(tdb, locking_key(dev, inode)) == 0;
}

/*******************************************************************
 Unlock a hash bucket entry.
******************************************************************/
BOOL unlock_share_entry(connection_struct *conn,
			SMB_DEV_T dev, SMB_INO_T inode)
{
	return tdb_unlockchain(tdb, locking_key(dev, inode)) == 0;
}


/*******************************************************************
 Lock a hash bucket entry. use a fsp for convenience
******************************************************************/
BOOL lock_share_entry_fsp(files_struct *fsp)
{
	return tdb_lockchain(tdb, locking_key(fsp->dev, fsp->inode)) == 0;
}

/*******************************************************************
 Unlock a hash bucket entry.
******************************************************************/
BOOL unlock_share_entry_fsp(files_struct *fsp)
{
	return tdb_unlockchain(tdb, locking_key(fsp->dev, fsp->inode)) == 0;
}

/*******************************************************************
 Get all share mode entries for a dev/inode pair.
********************************************************************/
int get_share_modes(connection_struct *conn, 
		    SMB_DEV_T dev, SMB_INO_T inode, 
		    share_mode_entry **shares)
{
	TDB_DATA dbuf;
	struct locking_data *data;
	int ret;

	*shares = NULL;

	dbuf = tdb_fetch(tdb, locking_key(dev, inode));
	if (!dbuf.dptr) return 0;

	data = (struct locking_data *)dbuf.dptr;
	ret = data->num_share_mode_entries;
	*shares = (share_mode_entry *)memdup(dbuf.dptr + sizeof(*data), ret * sizeof(**shares));
	free(dbuf.dptr);

	if (! *shares) return 0;

	return ret;
}

/*******************************************************************
 Del the share mode of a file for this process
********************************************************************/
void del_share_mode(files_struct *fsp)
{
	TDB_DATA dbuf;
	struct locking_data *data;
	int i, del_count=0;
	share_mode_entry *shares;
	pid_t pid = getpid();

	/* read in the existing share modes */
	dbuf = tdb_fetch(tdb, locking_key_fsp(fsp));
	if (!dbuf.dptr) return;

	data = (struct locking_data *)dbuf.dptr;
	shares = (share_mode_entry *)(dbuf.dptr + sizeof(*data));

	/* find any with our pid and delete it by overwriting with the rest of the data 
	   from the record */
	for (i=0;i<data->num_share_mode_entries;) {
		if (shares[i].pid == pid &&
		    memcmp(&shares[i].time, 
			   &fsp->open_time,sizeof(struct timeval)) == 0) {
			data->num_share_mode_entries--;
			memmove(&shares[i], &shares[i+1], 
				dbuf.dsize - (sizeof(*data) + (i+1)*sizeof(*shares)));
			del_count++;
		} else {
			i++;
		}
	}

	/* the record has shrunk a bit */
	dbuf.dsize -= del_count * sizeof(*shares);

	/* store it back in the database */
	tdb_store(tdb, locking_key_fsp(fsp), dbuf, TDB_REPLACE);

	free(dbuf.dptr);
}

/*******************************************************************
fill a share mode entry
********************************************************************/
static void fill_share_mode(char *p, files_struct *fsp, uint16 port, uint16 op_type)
{
	share_mode_entry *e = (share_mode_entry *)p;
	e->pid = getpid();
	e->share_mode = fsp->share_mode;
	e->op_port = port;
	e->op_type = op_type;
	memcpy((char *)&e->time, (char *)&fsp->open_time, sizeof(struct timeval));
}

/*******************************************************************
 Set the share mode of a file. Return False on fail, True on success.
********************************************************************/
BOOL set_share_mode(files_struct *fsp, uint16 port, uint16 op_type)
{
	TDB_DATA dbuf;
	struct locking_data *data;
	share_mode_entry *shares;
	char *p=NULL;
	int size;
		
	/* read in the existing share modes if any */
	dbuf = tdb_fetch(tdb, locking_key_fsp(fsp));
	if (!dbuf.dptr) {
		/* we'll need to create a new record */
		pstring fname;

		pstrcpy(fname, fsp->conn->connectpath);
		pstrcat(fname, "/");
		pstrcat(fname, fsp->fsp_name);

		size = sizeof(*data) + sizeof(*shares) + strlen(fname) + 1;
		p = (char *)malloc(size);
		data = (struct locking_data *)p;
		shares = (share_mode_entry *)(p + sizeof(*data));
		data->num_share_mode_entries = 1;
		pstrcpy(p + sizeof(*data) + sizeof(*shares), fname);
		fill_share_mode(p + sizeof(*data), fsp, port, op_type);
		dbuf.dptr = p;
		dbuf.dsize = size;
		tdb_store(tdb, locking_key_fsp(fsp), dbuf, TDB_REPLACE);
		free(p);
		return True;
	}

	/* we're adding to an existing entry - this is a bit fiddly */
	data = (struct locking_data *)dbuf.dptr;
	shares = (share_mode_entry *)(dbuf.dptr + sizeof(*data));

	data->num_share_mode_entries++;
	size = dbuf.dsize + sizeof(*shares);
	p = malloc(size);
	memcpy(p, dbuf.dptr, sizeof(*data));
	fill_share_mode(p + sizeof(*data), fsp, port, op_type);
	memcpy(p + sizeof(*data) + sizeof(*shares), dbuf.dptr + sizeof(*data),
	       dbuf.dsize - sizeof(*data));
	free(dbuf.dptr);
	dbuf.dptr = p;
	dbuf.dsize = size;
	tdb_store(tdb, locking_key_fsp(fsp), dbuf, TDB_REPLACE);
	free(p);
	return True;
}


/*******************************************************************
a generic in-place modification call for share mode entries
********************************************************************/
static BOOL mod_share_mode(files_struct *fsp,
			   void (*mod_fn)(share_mode_entry *, SMB_DEV_T, SMB_INO_T, void *),
			   void *param)
{
	TDB_DATA dbuf;
	struct locking_data *data;
	int i;
	share_mode_entry *shares;
	pid_t pid = getpid();
	int need_store=0;

	/* read in the existing share modes */
	dbuf = tdb_fetch(tdb, locking_key_fsp(fsp));
	if (!dbuf.dptr) return False;

	data = (struct locking_data *)dbuf.dptr;
	shares = (share_mode_entry *)(dbuf.dptr + sizeof(*data));

	/* find any with our pid and call the supplied function */
	for (i=0;i<data->num_share_mode_entries;i++) {
		if (pid == shares[i].pid && 
		    shares[i].share_mode == fsp->share_mode &&
		    memcmp(&shares[i].time, 
			   &fsp->open_time,sizeof(struct timeval)) == 0) {
			mod_fn(&shares[i], fsp->dev, fsp->inode, param);
			need_store=1;
		}
	}

	/* if the mod fn was called then store it back */
	if (need_store) {
		tdb_store(tdb, locking_key_fsp(fsp), dbuf, TDB_REPLACE);
	}

	free(dbuf.dptr);
	return need_store;
}


/*******************************************************************
 Static function that actually does the work for the generic function
 below.
********************************************************************/
static void remove_share_oplock_fn(share_mode_entry *entry, SMB_DEV_T dev, SMB_INO_T inode, 
                                   void *param)
{
	DEBUG(10,("remove_share_oplock_fn: removing oplock info for entry dev=%x ino=%.0f\n",
		  (unsigned int)dev, (double)inode ));
	/* Delete the oplock info. */
	entry->op_port = 0;
	entry->op_type = NO_OPLOCK;
}

/*******************************************************************
 Remove an oplock port and mode entry from a share mode.
********************************************************************/
BOOL remove_share_oplock(files_struct *fsp)
{
	return mod_share_mode(fsp, remove_share_oplock_fn, NULL);
}

/*******************************************************************
 Static function that actually does the work for the generic function
 below.
********************************************************************/
static void downgrade_share_oplock_fn(share_mode_entry *entry, SMB_DEV_T dev, SMB_INO_T inode, 
                                   void *param)
{
	DEBUG(10,("downgrade_share_oplock_fn: downgrading oplock info for entry dev=%x ino=%.0f\n",
		  (unsigned int)dev, (double)inode ));
	entry->op_type = LEVEL_II_OPLOCK;
}

/*******************************************************************
 Downgrade a oplock type from exclusive to level II.
********************************************************************/
BOOL downgrade_share_oplock(files_struct *fsp)
{
	return mod_share_mode(fsp, downgrade_share_oplock_fn, NULL);
}


/*******************************************************************
 Static function that actually does the work for the generic function
 below.
********************************************************************/
struct mod_val {
	int new_share_mode;
	uint16 new_oplock;
};

static void modify_share_mode_fn(share_mode_entry *entry, SMB_DEV_T dev, SMB_INO_T inode, 
                                   void *param)
{
	struct mod_val *mvp = (struct mod_val *)param;

	DEBUG(10,("modify_share_mode_fn: changing share mode info from %x to %x for entry dev=%x ino=%.0f\n",
        entry->share_mode, mvp->new_share_mode, (unsigned int)dev, (double)inode ));
	DEBUG(10,("modify_share_mode_fn: changing oplock state from %x to %x for entry dev=%x ino=%.0f\n",
        entry->op_type, (int)mvp->new_oplock, (unsigned int)dev, (double)inode ));
	/* Change the share mode info. */
	entry->share_mode = mvp->new_share_mode;
	entry->op_type = mvp->new_oplock;
}

/*******************************************************************
 Modify a share mode on a file. Used by the delete open file code.
 Return False on fail, True on success.
********************************************************************/
BOOL modify_share_mode(files_struct *fsp, int new_mode, uint16 new_oplock)
{
	struct mod_val mv;

	mv.new_share_mode = new_mode;
	mv.new_oplock = new_oplock;

	return mod_share_mode(fsp, modify_share_mode_fn, (void *)&mv);
}


/****************************************************************************
traverse the whole database with this function, calling traverse_callback
on each share mode
****************************************************************************/
static int traverse_fn(TDB_CONTEXT *the_tdb, TDB_DATA kbuf, TDB_DATA dbuf, 
                       void* state)
{
	struct locking_data *data;
	share_mode_entry *shares;
	char *name;
	int i;

	SHAREMODE_FN(traverse_callback) = (SHAREMODE_FN_CAST())state;

	data = (struct locking_data *)dbuf.dptr;
	shares = (share_mode_entry *)(dbuf.dptr + sizeof(*data));
	name = dbuf.dptr + sizeof(*data) + data->num_share_mode_entries*sizeof(*shares);

	for (i=0;i<data->num_share_mode_entries;i++) {
		traverse_callback(&shares[i], name);
	}
	return 0;
}

/*******************************************************************
 Call the specified function on each entry under management by the
 share mode system.
********************************************************************/
int share_mode_forall(SHAREMODE_FN(fn))
{
	if (!tdb) return 0;
	return tdb_traverse(tdb, traverse_fn, (void*)fn);
}