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Make use of ZERO_STRUCT instead of memset in namequery.c
[Samba.git] / source / locking / posix.c
blob1b88c472b0ea9492d7342f30ef0154077f8fcfc7
1 /*
2 Unix SMB/CIFS implementation.
3 Locking functions
4 Copyright (C) Jeremy Allison 1992-2006
5
6 This program is free software; you can redistribute it and/or modify
7 it under the terms of the GNU General Public License as published by
8 the Free Software Foundation; either version 3 of the License, or
9 (at your option) any later version.
10
11 This program is distributed in the hope that it will be useful,
12 but WITHOUT ANY WARRANTY; without even the implied warranty of
13 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
14 GNU General Public License for more details.
15
16 You should have received a copy of the GNU General Public License
17 along with this program. If not, see <http://www.gnu.org/licenses/>.
18
19 Revision History:
20
21 POSIX locking support. Jeremy Allison (jeremy@valinux.com), Apr. 2000.
22 */
23
24 #include "includes.h"
25
26 #undef DBGC_CLASS
27 #define DBGC_CLASS DBGC_LOCKING
28
29 /*
30 * The pending close database handle.
31 */
32
33 static struct db_context *posix_pending_close_db;
34
35 /****************************************************************************
36 First - the functions that deal with the underlying system locks - these
37 functions are used no matter if we're mapping CIFS Windows locks or CIFS
38 POSIX locks onto POSIX.
39 ****************************************************************************/
40
41 /****************************************************************************
42 Utility function to map a lock type correctly depending on the open
43 mode of a file.
44 ****************************************************************************/
45
46 static int map_posix_lock_type( files_struct *fsp, enum brl_type lock_type)
47 {
48 if((lock_type == WRITE_LOCK) && !fsp->can_write) {
49 /*
50 * Many UNIX's cannot get a write lock on a file opened read-only.
51 * Win32 locking semantics allow this.
52 * Do the best we can and attempt a read-only lock.
53 */
54 DEBUG(10,("map_posix_lock_type: Downgrading write lock to read due to read-only file.\n"));
55 return F_RDLCK;
56 }
57
58 /*
59 * This return should be the most normal, as we attempt
60 * to always open files read/write.
61 */
62
63 return (lock_type == READ_LOCK) ? F_RDLCK : F_WRLCK;
64 }
65
66 /****************************************************************************
67 Debugging aid :-).
68 ****************************************************************************/
69
70 static const char *posix_lock_type_name(int lock_type)
71 {
72 return (lock_type == F_RDLCK) ? "READ" : "WRITE";
73 }
74
75 /****************************************************************************
76 Check to see if the given unsigned lock range is within the possible POSIX
77 range. Modifies the given args to be in range if possible, just returns
78 False if not.
79 ****************************************************************************/
80
81 static bool posix_lock_in_range(SMB_OFF_T *offset_out, SMB_OFF_T *count_out,
82 SMB_BIG_UINT u_offset, SMB_BIG_UINT u_count)
83 {
84 SMB_OFF_T offset = (SMB_OFF_T)u_offset;
85 SMB_OFF_T count = (SMB_OFF_T)u_count;
86
87 /*
88 * For the type of system we are, attempt to
89 * find the maximum positive lock offset as an SMB_OFF_T.
90 */
91
92 #if defined(MAX_POSITIVE_LOCK_OFFSET) /* Some systems have arbitrary limits. */
93
94 SMB_OFF_T max_positive_lock_offset = (MAX_POSITIVE_LOCK_OFFSET);
95
96 #elif defined(LARGE_SMB_OFF_T) && !defined(HAVE_BROKEN_FCNTL64_LOCKS)
97
98 /*
99 * In this case SMB_OFF_T is 64 bits,
100 * and the underlying system can handle 64 bit signed locks.
101 */
102
103 SMB_OFF_T mask2 = ((SMB_OFF_T)0x4) << (SMB_OFF_T_BITS-4);
104 SMB_OFF_T mask = (mask2<<1);
105 SMB_OFF_T max_positive_lock_offset = ~mask;
106
107 #else /* !LARGE_SMB_OFF_T || HAVE_BROKEN_FCNTL64_LOCKS */
108
109 /*
110 * In this case either SMB_OFF_T is 32 bits,
111 * or the underlying system cannot handle 64 bit signed locks.
112 * All offsets & counts must be 2^31 or less.
113 */
114
115 SMB_OFF_T max_positive_lock_offset = 0x7FFFFFFF;
116
117 #endif /* !LARGE_SMB_OFF_T || HAVE_BROKEN_FCNTL64_LOCKS */
118
119 /*
120 * POSIX locks of length zero mean lock to end-of-file.
121 * Win32 locks of length zero are point probes. Ignore
122 * any Win32 locks of length zero. JRA.
123 */
124
125 if (count == (SMB_OFF_T)0) {
126 DEBUG(10,("posix_lock_in_range: count = 0, ignoring.\n"));
127 return False;
128 }
129
130 /*
131 * If the given offset was > max_positive_lock_offset then we cannot map this at all
132 * ignore this lock.
133 */
134
135 if (u_offset & ~((SMB_BIG_UINT)max_positive_lock_offset)) {
136 DEBUG(10,("posix_lock_in_range: (offset = %.0f) offset > %.0f and we cannot handle this. Ignoring lock.\n",
137 (double)u_offset, (double)((SMB_BIG_UINT)max_positive_lock_offset) ));
138 return False;
139 }
140
141 /*
142 * We must truncate the count to less than max_positive_lock_offset.
143 */
144
145 if (u_count & ~((SMB_BIG_UINT)max_positive_lock_offset)) {
146 count = max_positive_lock_offset;
147 }
148
149 /*
150 * Truncate count to end at max lock offset.
151 */
152
153 if (offset + count < 0 || offset + count > max_positive_lock_offset) {
154 count = max_positive_lock_offset - offset;
155 }
156
157 /*
158 * If we ate all the count, ignore this lock.
159 */
160
161 if (count == 0) {
162 DEBUG(10,("posix_lock_in_range: Count = 0. Ignoring lock u_offset = %.0f, u_count = %.0f\n",
163 (double)u_offset, (double)u_count ));
164 return False;
165 }
166
167 /*
168 * The mapping was successful.
169 */
170
171 DEBUG(10,("posix_lock_in_range: offset_out = %.0f, count_out = %.0f\n",
172 (double)offset, (double)count ));
173
174 *offset_out = offset;
175 *count_out = count;
176
177 return True;
178 }
179
180 /****************************************************************************
181 Actual function that does POSIX locks. Copes with 64 -> 32 bit cruft and
182 broken NFS implementations.
183 ****************************************************************************/
184
185 static bool posix_fcntl_lock(files_struct *fsp, int op, SMB_OFF_T offset, SMB_OFF_T count, int type)
186 {
187 bool ret;
188
189 DEBUG(8,("posix_fcntl_lock %d %d %.0f %.0f %d\n",fsp->fh->fd,op,(double)offset,(double)count,type));
190
191 ret = SMB_VFS_LOCK(fsp, op, offset, count, type);
192
193 if (!ret && ((errno == EFBIG) || (errno == ENOLCK) || (errno == EINVAL))) {
194
195 DEBUG(0,("posix_fcntl_lock: WARNING: lock request at offset %.0f, length %.0f returned\n",
196 (double)offset,(double)count));
197 DEBUGADD(0,("an %s error. This can happen when using 64 bit lock offsets\n", strerror(errno)));
198 DEBUGADD(0,("on 32 bit NFS mounted file systems.\n"));
199
200 /*
201 * If the offset is > 0x7FFFFFFF then this will cause problems on
202 * 32 bit NFS mounted filesystems. Just ignore it.
203 */
204
205 if (offset & ~((SMB_OFF_T)0x7fffffff)) {
206 DEBUG(0,("Offset greater than 31 bits. Returning success.\n"));
207 return True;
208 }
209
210 if (count & ~((SMB_OFF_T)0x7fffffff)) {
211 /* 32 bit NFS file system, retry with smaller offset */
212 DEBUG(0,("Count greater than 31 bits - retrying with 31 bit truncated length.\n"));
213 errno = 0;
214 count &= 0x7fffffff;
215 ret = SMB_VFS_LOCK(fsp, op, offset, count, type);
216 }
217 }
218
219 DEBUG(8,("posix_fcntl_lock: Lock call %s\n", ret ? "successful" : "failed"));
220 return ret;
221 }
222
223 /****************************************************************************
224 Actual function that gets POSIX locks. Copes with 64 -> 32 bit cruft and
225 broken NFS implementations.
226 ****************************************************************************/
227
228 static bool posix_fcntl_getlock(files_struct *fsp, SMB_OFF_T *poffset, SMB_OFF_T *pcount, int *ptype)
229 {
230 pid_t pid;
231 bool ret;
232
233 DEBUG(8,("posix_fcntl_getlock %d %.0f %.0f %d\n",
234 fsp->fh->fd,(double)*poffset,(double)*pcount,*ptype));
235
236 ret = SMB_VFS_GETLOCK(fsp, poffset, pcount, ptype, &pid);
237
238 if (!ret && ((errno == EFBIG) || (errno == ENOLCK) || (errno == EINVAL))) {
239
240 DEBUG(0,("posix_fcntl_getlock: WARNING: lock request at offset %.0f, length %.0f returned\n",
241 (double)*poffset,(double)*pcount));
242 DEBUGADD(0,("an %s error. This can happen when using 64 bit lock offsets\n", strerror(errno)));
243 DEBUGADD(0,("on 32 bit NFS mounted file systems.\n"));
244
245 /*
246 * If the offset is > 0x7FFFFFFF then this will cause problems on
247 * 32 bit NFS mounted filesystems. Just ignore it.
248 */
249
250 if (*poffset & ~((SMB_OFF_T)0x7fffffff)) {
251 DEBUG(0,("Offset greater than 31 bits. Returning success.\n"));
252 return True;
253 }
254
255 if (*pcount & ~((SMB_OFF_T)0x7fffffff)) {
256 /* 32 bit NFS file system, retry with smaller offset */
257 DEBUG(0,("Count greater than 31 bits - retrying with 31 bit truncated length.\n"));
258 errno = 0;
259 *pcount &= 0x7fffffff;
260 ret = SMB_VFS_GETLOCK(fsp,poffset,pcount,ptype,&pid);
261 }
262 }
263
264 DEBUG(8,("posix_fcntl_getlock: Lock query call %s\n", ret ? "successful" : "failed"));
265 return ret;
266 }
267
268 /****************************************************************************
269 POSIX function to see if a file region is locked. Returns True if the
270 region is locked, False otherwise.
271 ****************************************************************************/
272
273 bool is_posix_locked(files_struct *fsp,
274 SMB_BIG_UINT *pu_offset,
275 SMB_BIG_UINT *pu_count,
276 enum brl_type *plock_type,
277 enum brl_flavour lock_flav)
278 {
279 SMB_OFF_T offset;
280 SMB_OFF_T count;
281 int posix_lock_type = map_posix_lock_type(fsp,*plock_type);
282
283 DEBUG(10,("is_posix_locked: File %s, offset = %.0f, count = %.0f, type = %s\n",
284 fsp->fsp_name, (double)*pu_offset, (double)*pu_count, posix_lock_type_name(*plock_type) ));
285
286 /*
287 * If the requested lock won't fit in the POSIX range, we will
288 * never set it, so presume it is not locked.
289 */
290
291 if(!posix_lock_in_range(&offset, &count, *pu_offset, *pu_count)) {
292 return False;
293 }
294
295 if (!posix_fcntl_getlock(fsp,&offset,&count,&posix_lock_type)) {
296 return False;
297 }
298
299 if (posix_lock_type == F_UNLCK) {
300 return False;
301 }
302
303 if (lock_flav == POSIX_LOCK) {
304 /* Only POSIX lock queries need to know the details. */
305 *pu_offset = (SMB_BIG_UINT)offset;
306 *pu_count = (SMB_BIG_UINT)count;
307 *plock_type = (posix_lock_type == F_RDLCK) ? READ_LOCK : WRITE_LOCK;
308 }
309 return True;
310 }
311
312 /****************************************************************************
313 Next - the functions that deal with in memory database storing representations
314 of either Windows CIFS locks or POSIX CIFS locks.
315 ****************************************************************************/
316
317 /* The key used in the in-memory POSIX databases. */
318
319 struct lock_ref_count_key {
320 struct file_id id;
321 char r;
322 };
323
324 /*******************************************************************
325 Form a static locking key for a dev/inode pair for the lock ref count
326 ******************************************************************/
327
328 static TDB_DATA locking_ref_count_key_fsp(files_struct *fsp,
329 struct lock_ref_count_key *tmp)
330 {
331 ZERO_STRUCTP(tmp);
332 tmp->id = fsp->file_id;
333 tmp->r = 'r';
334 return make_tdb_data((uint8_t *)tmp, sizeof(*tmp));
335 }
336
337 /*******************************************************************
338 Convenience function to get an fd_array key from an fsp.
339 ******************************************************************/
340
341 static TDB_DATA fd_array_key_fsp(files_struct *fsp)
342 {
343 return make_tdb_data((uint8 *)&fsp->file_id, sizeof(fsp->file_id));
344 }
345
346 /*******************************************************************
347 Create the in-memory POSIX lock databases.
348 ********************************************************************/
349
350 bool posix_locking_init(bool read_only)
351 {
352 if (posix_pending_close_db != NULL) {
353 return true;
354 }
355
356 posix_pending_close_db = db_open_rbt(NULL);
357
358 if (posix_pending_close_db == NULL) {
359 DEBUG(0,("Failed to open POSIX pending close database.\n"));
360 return false;
361 }
362
363 return true;
364 }
365
366 /*******************************************************************
367 Delete the in-memory POSIX lock databases.
368 ********************************************************************/
369
370 bool posix_locking_end(void)
371 {
372 /*
373 * Shouldn't we close all fd's here?
374 */
375 TALLOC_FREE(posix_pending_close_db);
376 return true;
377 }
378
379 /****************************************************************************
380 Next - the functions that deal with storing fd's that have outstanding
381 POSIX locks when closed.
382 ****************************************************************************/
383
384 /****************************************************************************
385 The records in posix_pending_close_tdb are composed of an array of ints
386 keyed by dev/ino pair.
387 The first int is a reference count of the number of outstanding locks on
388 all open fd's on this dev/ino pair. Any subsequent ints are the fd's that
389 were open on this dev/ino pair that should have been closed, but can't as
390 the lock ref count is non zero.
391 ****************************************************************************/
392
393 /****************************************************************************
394 Keep a reference count of the number of Windows locks open on this dev/ino
395 pair. Creates entry if it doesn't exist.
396 ****************************************************************************/
397
398 static void increment_windows_lock_ref_count(files_struct *fsp)
399 {
400 struct lock_ref_count_key tmp;
401 struct db_record *rec;
402 int lock_ref_count = 0;
403 NTSTATUS status;
404
405 rec = posix_pending_close_db->fetch_locked(
406 posix_pending_close_db, talloc_tos(),
407 locking_ref_count_key_fsp(fsp, &tmp));
408
409 SMB_ASSERT(rec != NULL);
410
411 if (rec->value.dptr != NULL) {
412 SMB_ASSERT(rec->value.dsize == sizeof(lock_ref_count));
413 memcpy(&lock_ref_count, rec->value.dptr,
414 sizeof(lock_ref_count));
415 }
416
417 lock_ref_count++;
418
419 status = rec->store(rec, make_tdb_data((uint8 *)&lock_ref_count,
420 sizeof(lock_ref_count)), 0);
421
422 SMB_ASSERT(NT_STATUS_IS_OK(status));
423
424 TALLOC_FREE(rec);
425
426 DEBUG(10,("increment_windows_lock_ref_count for file now %s = %d\n",
427 fsp->fsp_name, lock_ref_count ));
428 }
429
430 /****************************************************************************
431 Bulk delete - subtract as many locks as we've just deleted.
432 ****************************************************************************/
433
434 void reduce_windows_lock_ref_count(files_struct *fsp, unsigned int dcount)
435 {
436 struct lock_ref_count_key tmp;
437 struct db_record *rec;
438 int lock_ref_count = 0;
439 NTSTATUS status;
440
441 rec = posix_pending_close_db->fetch_locked(
442 posix_pending_close_db, talloc_tos(),
443 locking_ref_count_key_fsp(fsp, &tmp));
444
445 SMB_ASSERT((rec != NULL)
446 && (rec->value.dptr != NULL)
447 && (rec->value.dsize == sizeof(lock_ref_count)));
448
449 memcpy(&lock_ref_count, rec->value.dptr, sizeof(lock_ref_count));
450
451 SMB_ASSERT(lock_ref_count > 0);
452
453 lock_ref_count -= dcount;
454
455 status = rec->store(rec, make_tdb_data((uint8 *)&lock_ref_count,
456 sizeof(lock_ref_count)), 0);
457
458 SMB_ASSERT(NT_STATUS_IS_OK(status));
459
460 TALLOC_FREE(rec);
461
462 DEBUG(10,("reduce_windows_lock_ref_count for file now %s = %d\n",
463 fsp->fsp_name, lock_ref_count ));
464 }
465
466 static void decrement_windows_lock_ref_count(files_struct *fsp)
467 {
468 reduce_windows_lock_ref_count(fsp, 1);
469 }
470
471 /****************************************************************************
472 Fetch the lock ref count.
473 ****************************************************************************/
474
475 static int get_windows_lock_ref_count(files_struct *fsp)
476 {
477 struct lock_ref_count_key tmp;
478 TDB_DATA dbuf;
479 int res;
480 int lock_ref_count = 0;
481
482 res = posix_pending_close_db->fetch(
483 posix_pending_close_db, talloc_tos(),
484 locking_ref_count_key_fsp(fsp, &tmp), &dbuf);
485
486 SMB_ASSERT(res == 0);
487
488 if (dbuf.dsize != 0) {
489 SMB_ASSERT(dbuf.dsize == sizeof(lock_ref_count));
490 memcpy(&lock_ref_count, dbuf.dptr, sizeof(lock_ref_count));
491 TALLOC_FREE(dbuf.dptr);
492 }
493
494 DEBUG(10,("get_windows_lock_count for file %s = %d\n",
495 fsp->fsp_name, lock_ref_count ));
496
497 return lock_ref_count;
498 }
499
500 /****************************************************************************
501 Delete a lock_ref_count entry.
502 ****************************************************************************/
503
504 static void delete_windows_lock_ref_count(files_struct *fsp)
505 {
506 struct lock_ref_count_key tmp;
507 struct db_record *rec;
508
509 rec = posix_pending_close_db->fetch_locked(
510 posix_pending_close_db, talloc_tos(),
511 locking_ref_count_key_fsp(fsp, &tmp));
512
513 SMB_ASSERT(rec != NULL);
514
515 /* Not a bug if it doesn't exist - no locks were ever granted. */
516
517 rec->delete_rec(rec);
518 TALLOC_FREE(rec);
519
520 DEBUG(10,("delete_windows_lock_ref_count for file %s\n",
521 fsp->fsp_name));
522 }
523
524 /****************************************************************************
525 Add an fd to the pending close tdb.
526 ****************************************************************************/
527
528 static void add_fd_to_close_entry(files_struct *fsp)
529 {
530 struct db_record *rec;
531 uint8_t *new_data;
532 NTSTATUS status;
533
534 rec = posix_pending_close_db->fetch_locked(
535 posix_pending_close_db, talloc_tos(),
536 fd_array_key_fsp(fsp));
537
538 SMB_ASSERT(rec != NULL);
539
540 new_data = TALLOC_ARRAY(
541 rec, uint8_t, rec->value.dsize + sizeof(fsp->fh->fd));
542
543 SMB_ASSERT(new_data != NULL);
544
545 memcpy(new_data, rec->value.dptr, rec->value.dsize);
546 memcpy(new_data + rec->value.dsize,
547 &fsp->fh->fd, sizeof(fsp->fh->fd));
548
549 status = rec->store(
550 rec, make_tdb_data(new_data,
551 rec->value.dsize + sizeof(fsp->fh->fd)), 0);
552
553 SMB_ASSERT(NT_STATUS_IS_OK(status));
554
555 TALLOC_FREE(rec);
556
557 DEBUG(10,("add_fd_to_close_entry: added fd %d file %s\n",
558 fsp->fh->fd, fsp->fsp_name ));
559 }
560
561 /****************************************************************************
562 Remove all fd entries for a specific dev/inode pair from the tdb.
563 ****************************************************************************/
564
565 static void delete_close_entries(files_struct *fsp)
566 {
567 struct db_record *rec;
568
569 rec = posix_pending_close_db->fetch_locked(
570 posix_pending_close_db, talloc_tos(),
571 fd_array_key_fsp(fsp));
572
573 SMB_ASSERT(rec != NULL);
574 rec->delete_rec(rec);
575 TALLOC_FREE(rec);
576 }
577
578 /****************************************************************************
579 Get the array of POSIX pending close records for an open fsp. Returns number
580 of entries.
581 ****************************************************************************/
582
583 static size_t get_posix_pending_close_entries(TALLOC_CTX *mem_ctx,
584 files_struct *fsp, int **entries)
585 {
586 TDB_DATA dbuf;
587 int res;
588
589 res = posix_pending_close_db->fetch(
590 posix_pending_close_db, mem_ctx, fd_array_key_fsp(fsp),
591 &dbuf);
592
593 SMB_ASSERT(res == 0);
594
595 if (dbuf.dsize == 0) {
596 *entries = NULL;
597 return 0;
598 }
599
600 *entries = (int *)dbuf.dptr;
601 return (size_t)(dbuf.dsize / sizeof(int));
602 }
603
604 /****************************************************************************
605 Deal with pending closes needed by POSIX locking support.
606 Note that posix_locking_close_file() is expected to have been called
607 to delete all locks on this fsp before this function is called.
608 ****************************************************************************/
609
610 NTSTATUS fd_close_posix(struct files_struct *fsp)
611 {
612 int saved_errno = 0;
613 int ret;
614 int *fd_array = NULL;
615 size_t count, i;
616
617 if (!lp_locking(fsp->conn->params) || !lp_posix_locking(fsp->conn->params)) {
618 /*
619 * No locking or POSIX to worry about or we want POSIX semantics
620 * which will lose all locks on all fd's open on this dev/inode,
621 * just close.
622 */
623 ret = SMB_VFS_CLOSE(fsp,fsp->fh->fd);
624 fsp->fh->fd = -1;
625 if (ret == -1) {
626 return map_nt_error_from_unix(errno);
627 }
628 return NT_STATUS_OK;
629 }
630
631 if (get_windows_lock_ref_count(fsp)) {
632
633 /*
634 * There are outstanding locks on this dev/inode pair on other fds.
635 * Add our fd to the pending close tdb and set fsp->fh->fd to -1.
636 */
637
638 add_fd_to_close_entry(fsp);
639 fsp->fh->fd = -1;
640 return NT_STATUS_OK;
641 }
642
643 /*
644 * No outstanding locks. Get the pending close fd's
645 * from the tdb and close them all.
646 */
647
648 count = get_posix_pending_close_entries(talloc_tos(), fsp, &fd_array);
649
650 if (count) {
651 DEBUG(10,("fd_close_posix: doing close on %u fd's.\n", (unsigned int)count ));
652
653 for(i = 0; i < count; i++) {
654 if (SMB_VFS_CLOSE(fsp,fd_array[i]) == -1) {
655 saved_errno = errno;
656 }
657 }
658
659 /*
660 * Delete all fd's stored in the tdb
661 * for this dev/inode pair.
662 */
663
664 delete_close_entries(fsp);
665 }
666
667 TALLOC_FREE(fd_array);
668
669 /* Don't need a lock ref count on this dev/ino anymore. */
670 delete_windows_lock_ref_count(fsp);
671
672 /*
673 * Finally close the fd associated with this fsp.
674 */
675
676 ret = SMB_VFS_CLOSE(fsp,fsp->fh->fd);
677
678 if (ret == 0 && saved_errno != 0) {
679 errno = saved_errno;
680 ret = -1;
681 }
682
683 fsp->fh->fd = -1;
684
685 if (ret == -1) {
686 return map_nt_error_from_unix(errno);
687 }
688
689 return NT_STATUS_OK;
690 }
691
692 /****************************************************************************
693 Next - the functions that deal with the mapping CIFS Windows locks onto
694 the underlying system POSIX locks.
695 ****************************************************************************/
696
697 /*
698 * Structure used when splitting a lock range
699 * into a POSIX lock range. Doubly linked list.
700 */
701
702 struct lock_list {
703 struct lock_list *next;
704 struct lock_list *prev;
705 SMB_OFF_T start;
706 SMB_OFF_T size;
707 };
708
709 /****************************************************************************
710 Create a list of lock ranges that don't overlap a given range. Used in calculating
711 POSIX locks and unlocks. This is a difficult function that requires ASCII art to
712 understand it :-).
713 ****************************************************************************/
714
715 static struct lock_list *posix_lock_list(TALLOC_CTX *ctx,
716 struct lock_list *lhead,
717 const struct lock_context *lock_ctx, /* Lock context lhead belongs to. */
718 files_struct *fsp,
719 const struct lock_struct *plocks,
720 int num_locks)
721 {
722 int i;
723
724 /*
725 * Check the current lock list on this dev/inode pair.
726 * Quit if the list is deleted.
727 */
728
729 DEBUG(10,("posix_lock_list: curr: start=%.0f,size=%.0f\n",
730 (double)lhead->start, (double)lhead->size ));
731
732 for (i=0; i<num_locks && lhead; i++) {
733 const struct lock_struct *lock = &plocks[i];
734 struct lock_list *l_curr;
735
736 /* Ignore all but read/write locks. */
737 if (lock->lock_type != READ_LOCK && lock->lock_type != WRITE_LOCK) {
738 continue;
739 }
740
741 /* Ignore locks not owned by this process. */
742 if (!procid_equal(&lock->context.pid, &lock_ctx->pid)) {
743 continue;
744 }
745
746 /*
747 * Walk the lock list, checking for overlaps. Note that
748 * the lock list can expand within this loop if the current
749 * range being examined needs to be split.
750 */
751
752 for (l_curr = lhead; l_curr;) {
753
754 DEBUG(10,("posix_lock_list: lock: fnum=%d: start=%.0f,size=%.0f:type=%s", lock->fnum,
755 (double)lock->start, (double)lock->size, posix_lock_type_name(lock->lock_type) ));
756
757 if ( (l_curr->start >= (lock->start + lock->size)) ||
758 (lock->start >= (l_curr->start + l_curr->size))) {
759
760 /* No overlap with existing lock - leave this range alone. */
761 /*********************************************
762 +---------+
763 | l_curr |
764 +---------+
765 +-------+
766 | lock |
767 +-------+
768 OR....
769 +---------+
770 | l_curr |
771 +---------+
772 **********************************************/
773
774 DEBUG(10,(" no overlap case.\n" ));
775
776 l_curr = l_curr->next;
777
778 } else if ( (l_curr->start >= lock->start) &&
779 (l_curr->start + l_curr->size <= lock->start + lock->size) ) {
780
781 /*
782 * This range is completely overlapped by this existing lock range
783 * and thus should have no effect. Delete it from the list.
784 */
785 /*********************************************
786 +---------+
787 | l_curr |
788 +---------+
789 +---------------------------+
790 | lock |
791 +---------------------------+
792 **********************************************/
793 /* Save the next pointer */
794 struct lock_list *ul_next = l_curr->next;
795
796 DEBUG(10,(" delete case.\n" ));
797
798 DLIST_REMOVE(lhead, l_curr);
799 if(lhead == NULL) {
800 break; /* No more list... */
801 }
802
803 l_curr = ul_next;
804
805 } else if ( (l_curr->start >= lock->start) &&
806 (l_curr->start < lock->start + lock->size) &&
807 (l_curr->start + l_curr->size > lock->start + lock->size) ) {
808
809 /*
810 * This range overlaps the existing lock range at the high end.
811 * Truncate by moving start to existing range end and reducing size.
812 */
813 /*********************************************
814 +---------------+
815 | l_curr |
816 +---------------+
817 +---------------+
818 | lock |
819 +---------------+
820 BECOMES....
821 +-------+
822 | l_curr|
823 +-------+
824 **********************************************/
825
826 l_curr->size = (l_curr->start + l_curr->size) - (lock->start + lock->size);
827 l_curr->start = lock->start + lock->size;
828
829 DEBUG(10,(" truncate high case: start=%.0f,size=%.0f\n",
830 (double)l_curr->start, (double)l_curr->size ));
831
832 l_curr = l_curr->next;
833
834 } else if ( (l_curr->start < lock->start) &&
835 (l_curr->start + l_curr->size > lock->start) &&
836 (l_curr->start + l_curr->size <= lock->start + lock->size) ) {
837
838 /*
839 * This range overlaps the existing lock range at the low end.
840 * Truncate by reducing size.
841 */
842 /*********************************************
843 +---------------+
844 | l_curr |
845 +---------------+
846 +---------------+
847 | lock |
848 +---------------+
849 BECOMES....
850 +-------+
851 | l_curr|
852 +-------+
853 **********************************************/
854
855 l_curr->size = lock->start - l_curr->start;
856
857 DEBUG(10,(" truncate low case: start=%.0f,size=%.0f\n",
858 (double)l_curr->start, (double)l_curr->size ));
859
860 l_curr = l_curr->next;
861
862 } else if ( (l_curr->start < lock->start) &&
863 (l_curr->start + l_curr->size > lock->start + lock->size) ) {
864 /*
865 * Worst case scenario. Range completely overlaps an existing
866 * lock range. Split the request into two, push the new (upper) request
867 * into the dlink list, and continue with the entry after l_new (as we
868 * know that l_new will not overlap with this lock).
869 */
870 /*********************************************
871 +---------------------------+
872 | l_curr |
873 +---------------------------+
874 +---------+
875 | lock |
876 +---------+
877 BECOMES.....
878 +-------+ +---------+
879 | l_curr| | l_new |
880 +-------+ +---------+
881 **********************************************/
882 struct lock_list *l_new = TALLOC_P(ctx, struct lock_list);
883
884 if(l_new == NULL) {
885 DEBUG(0,("posix_lock_list: talloc fail.\n"));
886 return NULL; /* The talloc_destroy takes care of cleanup. */
887 }
888
889 ZERO_STRUCTP(l_new);
890 l_new->start = lock->start + lock->size;
891 l_new->size = l_curr->start + l_curr->size - l_new->start;
892
893 /* Truncate the l_curr. */
894 l_curr->size = lock->start - l_curr->start;
895
896 DEBUG(10,(" split case: curr: start=%.0f,size=%.0f \
897 new: start=%.0f,size=%.0f\n", (double)l_curr->start, (double)l_curr->size,
898 (double)l_new->start, (double)l_new->size ));
899
900 /*
901 * Add into the dlink list after the l_curr point - NOT at lhead.
902 * Note we can't use DLINK_ADD here as this inserts at the head of the given list.
903 */
904
905 l_new->prev = l_curr;
906 l_new->next = l_curr->next;
907 l_curr->next = l_new;
908
909 /* And move after the link we added. */
910 l_curr = l_new->next;
911
912 } else {
913
914 /*
915 * This logic case should never happen. Ensure this is the
916 * case by forcing an abort.... Remove in production.
917 */
918 char *msg = NULL;
919
920 /* Don't check if alloc succeeds here - we're
921 * forcing a core dump anyway. */
922
923 asprintf(&msg, "logic flaw in cases: l_curr: start = %.0f, size = %.0f : \
924 lock: start = %.0f, size = %.0f", (double)l_curr->start, (double)l_curr->size, (double)lock->start, (double)lock->size );
925
926 smb_panic(msg);
927 }
928 } /* end for ( l_curr = lhead; l_curr;) */
929 } /* end for (i=0; i<num_locks && ul_head; i++) */
930
931 return lhead;
932 }
933
934 /****************************************************************************
935 POSIX function to acquire a lock. Returns True if the
936 lock could be granted, False if not.
937 ****************************************************************************/
938
939 bool set_posix_lock_windows_flavour(files_struct *fsp,
940 SMB_BIG_UINT u_offset,
941 SMB_BIG_UINT u_count,
942 enum brl_type lock_type,
943 const struct lock_context *lock_ctx,
944 const struct lock_struct *plocks,
945 int num_locks,
946 int *errno_ret)
947 {
948 SMB_OFF_T offset;
949 SMB_OFF_T count;
950 int posix_lock_type = map_posix_lock_type(fsp,lock_type);
951 bool ret = True;
952 size_t lock_count;
953 TALLOC_CTX *l_ctx = NULL;
954 struct lock_list *llist = NULL;
955 struct lock_list *ll = NULL;
956
957 DEBUG(5,("set_posix_lock_windows_flavour: File %s, offset = %.0f, count = %.0f, type = %s\n",
958 fsp->fsp_name, (double)u_offset, (double)u_count, posix_lock_type_name(lock_type) ));
959
960 /*
961 * If the requested lock won't fit in the POSIX range, we will
962 * pretend it was successful.
963 */
964
965 if(!posix_lock_in_range(&offset, &count, u_offset, u_count)) {
966 increment_windows_lock_ref_count(fsp);
967 return True;
968 }
969
970 /*
971 * Windows is very strange. It allows read locks to be overlayed
972 * (even over a write lock), but leaves the write lock in force until the first
973 * unlock. It also reference counts the locks. This means the following sequence :
974 *
975 * process1 process2
976 * ------------------------------------------------------------------------
977 * WRITE LOCK : start = 2, len = 10
978 * READ LOCK: start =0, len = 10 - FAIL
979 * READ LOCK : start = 0, len = 14
980 * READ LOCK: start =0, len = 10 - FAIL
981 * UNLOCK : start = 2, len = 10
982 * READ LOCK: start =0, len = 10 - OK
983 *
984 * Under POSIX, the same sequence in steps 1 and 2 would not be reference counted, but
985 * would leave a single read lock over the 0-14 region.
986 */
987
988 if ((l_ctx = talloc_init("set_posix_lock")) == NULL) {
989 DEBUG(0,("set_posix_lock_windows_flavour: unable to init talloc context.\n"));
990 return False;
991 }
992
993 if ((ll = TALLOC_P(l_ctx, struct lock_list)) == NULL) {
994 DEBUG(0,("set_posix_lock_windows_flavour: unable to talloc unlock list.\n"));
995 talloc_destroy(l_ctx);
996 return False;
997 }
998
999 /*
1000 * Create the initial list entry containing the
1001 * lock we want to add.
1002 */
1003
1004 ZERO_STRUCTP(ll);
1005 ll->start = offset;
1006 ll->size = count;
1007
1008 DLIST_ADD(llist, ll);
1009
1010 /*
1011 * The following call calculates if there are any
1012 * overlapping locks held by this process on
1013 * fd's open on the same file and splits this list
1014 * into a list of lock ranges that do not overlap with existing
1015 * POSIX locks.
1016 */
1017
1018 llist = posix_lock_list(l_ctx,
1019 llist,
1020 lock_ctx, /* Lock context llist belongs to. */
1021 fsp,
1022 plocks,
1023 num_locks);
1024
1025 /*
1026 * Add the POSIX locks on the list of ranges returned.
1027 * As the lock is supposed to be added atomically, we need to
1028 * back out all the locks if any one of these calls fail.
1029 */
1030
1031 for (lock_count = 0, ll = llist; ll; ll = ll->next, lock_count++) {
1032 offset = ll->start;
1033 count = ll->size;
1034
1035 DEBUG(5,("set_posix_lock_windows_flavour: Real lock: Type = %s: offset = %.0f, count = %.0f\n",
1036 posix_lock_type_name(posix_lock_type), (double)offset, (double)count ));
1037
1038 if (!posix_fcntl_lock(fsp,SMB_F_SETLK,offset,count,posix_lock_type)) {
1039 *errno_ret = errno;
1040 DEBUG(5,("set_posix_lock_windows_flavour: Lock fail !: Type = %s: offset = %.0f, count = %.0f. Errno = %s\n",
1041 posix_lock_type_name(posix_lock_type), (double)offset, (double)count, strerror(errno) ));
1042 ret = False;
1043 break;
1044 }
1045 }
1046
1047 if (!ret) {
1048
1049 /*
1050 * Back out all the POSIX locks we have on fail.
1051 */
1052
1053 for (ll = llist; lock_count; ll = ll->next, lock_count--) {
1054 offset = ll->start;
1055 count = ll->size;
1056
1057 DEBUG(5,("set_posix_lock_windows_flavour: Backing out locks: Type = %s: offset = %.0f, count = %.0f\n",
1058 posix_lock_type_name(posix_lock_type), (double)offset, (double)count ));
1059
1060 posix_fcntl_lock(fsp,SMB_F_SETLK,offset,count,F_UNLCK);
1061 }
1062 } else {
1063 /* Remember the number of Windows locks we have on this dev/ino pair. */
1064 increment_windows_lock_ref_count(fsp);
1065 }
1066
1067 talloc_destroy(l_ctx);
1068 return ret;
1069 }
1070
1071 /****************************************************************************
1072 POSIX function to release a lock. Returns True if the
1073 lock could be released, False if not.
1074 ****************************************************************************/
1075
1076 bool release_posix_lock_windows_flavour(files_struct *fsp,
1077 SMB_BIG_UINT u_offset,
1078 SMB_BIG_UINT u_count,
1079 enum brl_type deleted_lock_type,
1080 const struct lock_context *lock_ctx,
1081 const struct lock_struct *plocks,
1082 int num_locks)
1083 {
1084 SMB_OFF_T offset;
1085 SMB_OFF_T count;
1086 bool ret = True;
1087 TALLOC_CTX *ul_ctx = NULL;
1088 struct lock_list *ulist = NULL;
1089 struct lock_list *ul = NULL;
1090
1091 DEBUG(5,("release_posix_lock_windows_flavour: File %s, offset = %.0f, count = %.0f\n",
1092 fsp->fsp_name, (double)u_offset, (double)u_count ));
1093
1094 /* Remember the number of Windows locks we have on this dev/ino pair. */
1095 decrement_windows_lock_ref_count(fsp);
1096
1097 /*
1098 * If the requested lock won't fit in the POSIX range, we will
1099 * pretend it was successful.
1100 */
1101
1102 if(!posix_lock_in_range(&offset, &count, u_offset, u_count)) {
1103 return True;
1104 }
1105
1106 if ((ul_ctx = talloc_init("release_posix_lock")) == NULL) {
1107 DEBUG(0,("release_posix_lock_windows_flavour: unable to init talloc context.\n"));
1108 return False;
1109 }
1110
1111 if ((ul = TALLOC_P(ul_ctx, struct lock_list)) == NULL) {
1112 DEBUG(0,("release_posix_lock_windows_flavour: unable to talloc unlock list.\n"));
1113 talloc_destroy(ul_ctx);
1114 return False;
1115 }
1116
1117 /*
1118 * Create the initial list entry containing the
1119 * lock we want to remove.
1120 */
1121
1122 ZERO_STRUCTP(ul);
1123 ul->start = offset;
1124 ul->size = count;
1125
1126 DLIST_ADD(ulist, ul);
1127
1128 /*
1129 * The following call calculates if there are any
1130 * overlapping locks held by this process on
1131 * fd's open on the same file and creates a
1132 * list of unlock ranges that will allow
1133 * POSIX lock ranges to remain on the file whilst the
1134 * unlocks are performed.
1135 */
1136
1137 ulist = posix_lock_list(ul_ctx,
1138 ulist,
1139 lock_ctx, /* Lock context ulist belongs to. */
1140 fsp,
1141 plocks,
1142 num_locks);
1143
1144 /*
1145 * If there were any overlapped entries (list is > 1 or size or start have changed),
1146 * and the lock_type we just deleted from
1147 * the upper layer tdb was a write lock, then before doing the unlock we need to downgrade
1148 * the POSIX lock to a read lock. This allows any overlapping read locks
1149 * to be atomically maintained.
1150 */
1151
1152 if (deleted_lock_type == WRITE_LOCK &&
1153 (!ulist || ulist->next != NULL || ulist->start != offset || ulist->size != count)) {
1154
1155 DEBUG(5,("release_posix_lock_windows_flavour: downgrading lock to READ: offset = %.0f, count = %.0f\n",
1156 (double)offset, (double)count ));
1157
1158 if (!posix_fcntl_lock(fsp,SMB_F_SETLK,offset,count,F_RDLCK)) {
1159 DEBUG(0,("release_posix_lock_windows_flavour: downgrade of lock failed with error %s !\n", strerror(errno) ));
1160 talloc_destroy(ul_ctx);
1161 return False;
1162 }
1163 }
1164
1165 /*
1166 * Release the POSIX locks on the list of ranges returned.
1167 */
1168
1169 for(; ulist; ulist = ulist->next) {
1170 offset = ulist->start;
1171 count = ulist->size;
1172
1173 DEBUG(5,("release_posix_lock_windows_flavour: Real unlock: offset = %.0f, count = %.0f\n",
1174 (double)offset, (double)count ));
1175
1176 if (!posix_fcntl_lock(fsp,SMB_F_SETLK,offset,count,F_UNLCK)) {
1177 ret = False;
1178 }
1179 }
1180
1181 talloc_destroy(ul_ctx);
1182 return ret;
1183 }
1184
1185 /****************************************************************************
1186 Next - the functions that deal with mapping CIFS POSIX locks onto
1187 the underlying system POSIX locks.
1188 ****************************************************************************/
1189
1190 /****************************************************************************
1191 POSIX function to acquire a lock. Returns True if the
1192 lock could be granted, False if not.
1193 As POSIX locks don't stack or conflict (they just overwrite)
1194 we can map the requested lock directly onto a system one. We
1195 know it doesn't conflict with locks on other contexts as the
1196 upper layer would have refused it.
1197 ****************************************************************************/
1198
1199 bool set_posix_lock_posix_flavour(files_struct *fsp,
1200 SMB_BIG_UINT u_offset,
1201 SMB_BIG_UINT u_count,
1202 enum brl_type lock_type,
1203 int *errno_ret)
1204 {
1205 SMB_OFF_T offset;
1206 SMB_OFF_T count;
1207 int posix_lock_type = map_posix_lock_type(fsp,lock_type);
1208
1209 DEBUG(5,("set_posix_lock_posix_flavour: File %s, offset = %.0f, count = %.0f, type = %s\n",
1210 fsp->fsp_name, (double)u_offset, (double)u_count, posix_lock_type_name(lock_type) ));
1211
1212 /*
1213 * If the requested lock won't fit in the POSIX range, we will
1214 * pretend it was successful.
1215 */
1216
1217 if(!posix_lock_in_range(&offset, &count, u_offset, u_count)) {
1218 return True;
1219 }
1220
1221 if (!posix_fcntl_lock(fsp,SMB_F_SETLK,offset,count,posix_lock_type)) {
1222 *errno_ret = errno;
1223 DEBUG(5,("set_posix_lock_posix_flavour: Lock fail !: Type = %s: offset = %.0f, count = %.0f. Errno = %s\n",
1224 posix_lock_type_name(posix_lock_type), (double)offset, (double)count, strerror(errno) ));
1225 return False;
1226 }
1227 return True;
1228 }
1229
1230 /****************************************************************************
1231 POSIX function to release a lock. Returns True if the
1232 lock could be released, False if not.
1233 We are given a complete lock state from the upper layer which is what the lock
1234 state should be after the unlock has already been done, so what
1235 we do is punch out holes in the unlock range where locks owned by this process
1236 have a different lock context.
1237 ****************************************************************************/
1238
1239 bool release_posix_lock_posix_flavour(files_struct *fsp,
1240 SMB_BIG_UINT u_offset,
1241 SMB_BIG_UINT u_count,
1242 const struct lock_context *lock_ctx,
1243 const struct lock_struct *plocks,
1244 int num_locks)
1245 {
1246 bool ret = True;
1247 SMB_OFF_T offset;
1248 SMB_OFF_T count;
1249 TALLOC_CTX *ul_ctx = NULL;
1250 struct lock_list *ulist = NULL;
1251 struct lock_list *ul = NULL;
1252
1253 DEBUG(5,("release_posix_lock_posix_flavour: File %s, offset = %.0f, count = %.0f\n",
1254 fsp->fsp_name, (double)u_offset, (double)u_count ));
1255
1256 /*
1257 * If the requested lock won't fit in the POSIX range, we will
1258 * pretend it was successful.
1259 */
1260
1261 if(!posix_lock_in_range(&offset, &count, u_offset, u_count)) {
1262 return True;
1263 }
1264
1265 if ((ul_ctx = talloc_init("release_posix_lock")) == NULL) {
1266 DEBUG(0,("release_posix_lock_windows_flavour: unable to init talloc context.\n"));
1267 return False;
1268 }
1269
1270 if ((ul = TALLOC_P(ul_ctx, struct lock_list)) == NULL) {
1271 DEBUG(0,("release_posix_lock_windows_flavour: unable to talloc unlock list.\n"));
1272 talloc_destroy(ul_ctx);
1273 return False;
1274 }
1275
1276 /*
1277 * Create the initial list entry containing the
1278 * lock we want to remove.
1279 */
1280
1281 ZERO_STRUCTP(ul);
1282 ul->start = offset;
1283 ul->size = count;
1284
1285 DLIST_ADD(ulist, ul);
1286
1287 /*
1288 * Walk the given array creating a linked list
1289 * of unlock requests.
1290 */
1291
1292 ulist = posix_lock_list(ul_ctx,
1293 ulist,
1294 lock_ctx, /* Lock context ulist belongs to. */
1295 fsp,
1296 plocks,
1297 num_locks);
1298
1299 /*
1300 * Release the POSIX locks on the list of ranges returned.
1301 */
1302
1303 for(; ulist; ulist = ulist->next) {
1304 offset = ulist->start;
1305 count = ulist->size;
1306
1307 DEBUG(5,("release_posix_lock_posix_flavour: Real unlock: offset = %.0f, count = %.0f\n",
1308 (double)offset, (double)count ));
1309
1310 if (!posix_fcntl_lock(fsp,SMB_F_SETLK,offset,count,F_UNLCK)) {
1311 ret = False;
1312 }
1313 }
1314
1315 talloc_destroy(ul_ctx);
1316 return ret;
1317 }
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