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[samba.git] / source3 / locking / posix.c
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                                 uint64_t u_offset, uint64_t 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 & ~((uint64_t)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)((uint64_t)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 & ~((uint64_t)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 bool smb_vfs_call_lock(struct vfs_handle_struct *handle,
181                        struct files_struct *fsp, int op, SMB_OFF_T offset,
182                        SMB_OFF_T count, int type)
183 {
184         VFS_FIND(lock);
185         return handle->fns->lock(handle, fsp, op, offset, count, type);
186 }
187
188 /****************************************************************************
189  Actual function that does POSIX locks. Copes with 64 -> 32 bit cruft and
190  broken NFS implementations.
191 ****************************************************************************/
192
193 static bool posix_fcntl_lock(files_struct *fsp, int op, SMB_OFF_T offset, SMB_OFF_T count, int type)
194 {
195         bool ret;
196
197         DEBUG(8,("posix_fcntl_lock %d %d %.0f %.0f %d\n",fsp->fh->fd,op,(double)offset,(double)count,type));
198
199         ret = SMB_VFS_LOCK(fsp, op, offset, count, type);
200
201         if (!ret && ((errno == EFBIG) || (errno == ENOLCK) || (errno ==  EINVAL))) {
202
203                 DEBUG(0,("posix_fcntl_lock: WARNING: lock request at offset %.0f, length %.0f returned\n",
204                                         (double)offset,(double)count));
205                 DEBUGADD(0,("an %s error. This can happen when using 64 bit lock offsets\n", strerror(errno)));
206                 DEBUGADD(0,("on 32 bit NFS mounted file systems.\n"));
207
208                 /*
209                  * If the offset is > 0x7FFFFFFF then this will cause problems on
210                  * 32 bit NFS mounted filesystems. Just ignore it.
211                  */
212
213                 if (offset & ~((SMB_OFF_T)0x7fffffff)) {
214                         DEBUG(0,("Offset greater than 31 bits. Returning success.\n"));
215                         return True;
216                 }
217
218                 if (count & ~((SMB_OFF_T)0x7fffffff)) {
219                         /* 32 bit NFS file system, retry with smaller offset */
220                         DEBUG(0,("Count greater than 31 bits - retrying with 31 bit truncated length.\n"));
221                         errno = 0;
222                         count &= 0x7fffffff;
223                         ret = SMB_VFS_LOCK(fsp, op, offset, count, type);
224                 }
225         }
226
227         DEBUG(8,("posix_fcntl_lock: Lock call %s\n", ret ? "successful" : "failed"));
228         return ret;
229 }
230
231 bool smb_vfs_call_getlock(struct vfs_handle_struct *handle,
232                           struct files_struct *fsp, SMB_OFF_T *poffset,
233                           SMB_OFF_T *pcount, int *ptype, pid_t *ppid)
234 {
235         VFS_FIND(getlock);
236         return handle->fns->getlock(handle, fsp, poffset, pcount, ptype, ppid);
237 }
238
239 /****************************************************************************
240  Actual function that gets POSIX locks. Copes with 64 -> 32 bit cruft and
241  broken NFS implementations.
242 ****************************************************************************/
243
244 static bool posix_fcntl_getlock(files_struct *fsp, SMB_OFF_T *poffset, SMB_OFF_T *pcount, int *ptype)
245 {
246         pid_t pid;
247         bool ret;
248
249         DEBUG(8,("posix_fcntl_getlock %d %.0f %.0f %d\n",
250                 fsp->fh->fd,(double)*poffset,(double)*pcount,*ptype));
251
252         ret = SMB_VFS_GETLOCK(fsp, poffset, pcount, ptype, &pid);
253
254         if (!ret && ((errno == EFBIG) || (errno == ENOLCK) || (errno ==  EINVAL))) {
255
256                 DEBUG(0,("posix_fcntl_getlock: WARNING: lock request at offset %.0f, length %.0f returned\n",
257                                         (double)*poffset,(double)*pcount));
258                 DEBUGADD(0,("an %s error. This can happen when using 64 bit lock offsets\n", strerror(errno)));
259                 DEBUGADD(0,("on 32 bit NFS mounted file systems.\n"));
260
261                 /*
262                  * If the offset is > 0x7FFFFFFF then this will cause problems on
263                  * 32 bit NFS mounted filesystems. Just ignore it.
264                  */
265
266                 if (*poffset & ~((SMB_OFF_T)0x7fffffff)) {
267                         DEBUG(0,("Offset greater than 31 bits. Returning success.\n"));
268                         return True;
269                 }
270
271                 if (*pcount & ~((SMB_OFF_T)0x7fffffff)) {
272                         /* 32 bit NFS file system, retry with smaller offset */
273                         DEBUG(0,("Count greater than 31 bits - retrying with 31 bit truncated length.\n"));
274                         errno = 0;
275                         *pcount &= 0x7fffffff;
276                         ret = SMB_VFS_GETLOCK(fsp,poffset,pcount,ptype,&pid);
277                 }
278         }
279
280         DEBUG(8,("posix_fcntl_getlock: Lock query call %s\n", ret ? "successful" : "failed"));
281         return ret;
282 }
283
284 /****************************************************************************
285  POSIX function to see if a file region is locked. Returns True if the
286  region is locked, False otherwise.
287 ****************************************************************************/
288
289 bool is_posix_locked(files_struct *fsp,
290                         uint64_t *pu_offset,
291                         uint64_t *pu_count,
292                         enum brl_type *plock_type,
293                         enum brl_flavour lock_flav)
294 {
295         SMB_OFF_T offset;
296         SMB_OFF_T count;
297         int posix_lock_type = map_posix_lock_type(fsp,*plock_type);
298
299         DEBUG(10,("is_posix_locked: File %s, offset = %.0f, count = %.0f, "
300                   "type = %s\n", fsp_str_dbg(fsp), (double)*pu_offset,
301                   (double)*pu_count,  posix_lock_type_name(*plock_type)));
302
303         /*
304          * If the requested lock won't fit in the POSIX range, we will
305          * never set it, so presume it is not locked.
306          */
307
308         if(!posix_lock_in_range(&offset, &count, *pu_offset, *pu_count)) {
309                 return False;
310         }
311
312         if (!posix_fcntl_getlock(fsp,&offset,&count,&posix_lock_type)) {
313                 return False;
314         }
315
316         if (posix_lock_type == F_UNLCK) {
317                 return False;
318         }
319
320         if (lock_flav == POSIX_LOCK) {
321                 /* Only POSIX lock queries need to know the details. */
322                 *pu_offset = (uint64_t)offset;
323                 *pu_count = (uint64_t)count;
324                 *plock_type = (posix_lock_type == F_RDLCK) ? READ_LOCK : WRITE_LOCK;
325         }
326         return True;
327 }
328
329 /****************************************************************************
330  Next - the functions that deal with in memory database storing representations
331  of either Windows CIFS locks or POSIX CIFS locks.
332 ****************************************************************************/
333
334 /* The key used in the in-memory POSIX databases. */
335
336 struct lock_ref_count_key {
337         struct file_id id;
338         char r;
339 }; 
340
341 /*******************************************************************
342  Form a static locking key for a dev/inode pair for the lock ref count
343 ******************************************************************/
344
345 static TDB_DATA locking_ref_count_key_fsp(files_struct *fsp,
346                                           struct lock_ref_count_key *tmp)
347 {
348         ZERO_STRUCTP(tmp);
349         tmp->id = fsp->file_id;
350         tmp->r = 'r';
351         return make_tdb_data((uint8_t *)tmp, sizeof(*tmp));
352 }
353
354 /*******************************************************************
355  Convenience function to get an fd_array key from an fsp.
356 ******************************************************************/
357
358 static TDB_DATA fd_array_key_fsp(files_struct *fsp)
359 {
360         return make_tdb_data((uint8 *)&fsp->file_id, sizeof(fsp->file_id));
361 }
362
363 /*******************************************************************
364  Create the in-memory POSIX lock databases.
365 ********************************************************************/
366
367 bool posix_locking_init(bool read_only)
368 {
369         if (posix_pending_close_db != NULL) {
370                 return true;
371         }
372
373         posix_pending_close_db = db_open_rbt(NULL);
374
375         if (posix_pending_close_db == NULL) {
376                 DEBUG(0,("Failed to open POSIX pending close database.\n"));
377                 return false;
378         }
379
380         return true;
381 }
382
383 /*******************************************************************
384  Delete the in-memory POSIX lock databases.
385 ********************************************************************/
386
387 bool posix_locking_end(void)
388 {
389         /*
390          * Shouldn't we close all fd's here?
391          */
392         TALLOC_FREE(posix_pending_close_db);
393         return true;
394 }
395
396 /****************************************************************************
397  Next - the functions that deal with storing fd's that have outstanding
398  POSIX locks when closed.
399 ****************************************************************************/
400
401 /****************************************************************************
402  The records in posix_pending_close_tdb are composed of an array of ints
403  keyed by dev/ino pair.
404  The first int is a reference count of the number of outstanding locks on
405  all open fd's on this dev/ino pair. Any subsequent ints are the fd's that
406  were open on this dev/ino pair that should have been closed, but can't as
407  the lock ref count is non zero.
408 ****************************************************************************/
409
410 /****************************************************************************
411  Keep a reference count of the number of Windows locks open on this dev/ino
412  pair. Creates entry if it doesn't exist.
413 ****************************************************************************/
414
415 static void increment_windows_lock_ref_count(files_struct *fsp)
416 {
417         struct lock_ref_count_key tmp;
418         struct db_record *rec;
419         int lock_ref_count = 0;
420         NTSTATUS status;
421
422         rec = posix_pending_close_db->fetch_locked(
423                 posix_pending_close_db, talloc_tos(),
424                 locking_ref_count_key_fsp(fsp, &tmp));
425
426         SMB_ASSERT(rec != NULL);
427
428         if (rec->value.dptr != NULL) {
429                 SMB_ASSERT(rec->value.dsize == sizeof(lock_ref_count));
430                 memcpy(&lock_ref_count, rec->value.dptr,
431                        sizeof(lock_ref_count));
432         }
433
434         lock_ref_count++;
435
436         status = rec->store(rec, make_tdb_data((uint8 *)&lock_ref_count,
437                                                sizeof(lock_ref_count)), 0);
438
439         SMB_ASSERT(NT_STATUS_IS_OK(status));
440
441         TALLOC_FREE(rec);
442
443         DEBUG(10,("increment_windows_lock_ref_count for file now %s = %d\n",
444                   fsp_str_dbg(fsp), lock_ref_count));
445 }
446
447 /****************************************************************************
448  Bulk delete - subtract as many locks as we've just deleted.
449 ****************************************************************************/
450
451 void reduce_windows_lock_ref_count(files_struct *fsp, unsigned int dcount)
452 {
453         struct lock_ref_count_key tmp;
454         struct db_record *rec;
455         int lock_ref_count = 0;
456         NTSTATUS status;
457
458         rec = posix_pending_close_db->fetch_locked(
459                 posix_pending_close_db, talloc_tos(),
460                 locking_ref_count_key_fsp(fsp, &tmp));
461
462         SMB_ASSERT((rec != NULL)
463                    && (rec->value.dptr != NULL)
464                    && (rec->value.dsize == sizeof(lock_ref_count)));
465
466         memcpy(&lock_ref_count, rec->value.dptr, sizeof(lock_ref_count));
467
468         SMB_ASSERT(lock_ref_count > 0);
469
470         lock_ref_count -= dcount;
471
472         status = rec->store(rec, make_tdb_data((uint8 *)&lock_ref_count,
473                                                sizeof(lock_ref_count)), 0);
474
475         SMB_ASSERT(NT_STATUS_IS_OK(status));
476
477         TALLOC_FREE(rec);
478
479         DEBUG(10,("reduce_windows_lock_ref_count for file now %s = %d\n",
480                   fsp_str_dbg(fsp), lock_ref_count));
481 }
482
483 static void decrement_windows_lock_ref_count(files_struct *fsp)
484 {
485         reduce_windows_lock_ref_count(fsp, 1);
486 }
487
488 /****************************************************************************
489  Fetch the lock ref count.
490 ****************************************************************************/
491
492 static int get_windows_lock_ref_count(files_struct *fsp)
493 {
494         struct lock_ref_count_key tmp;
495         TDB_DATA dbuf;
496         int res;
497         int lock_ref_count = 0;
498
499         res = posix_pending_close_db->fetch(
500                 posix_pending_close_db, talloc_tos(),
501                 locking_ref_count_key_fsp(fsp, &tmp), &dbuf);
502
503         SMB_ASSERT(res == 0);
504
505         if (dbuf.dsize != 0) {
506                 SMB_ASSERT(dbuf.dsize == sizeof(lock_ref_count));
507                 memcpy(&lock_ref_count, dbuf.dptr, sizeof(lock_ref_count));
508                 TALLOC_FREE(dbuf.dptr);
509         }
510
511         DEBUG(10,("get_windows_lock_count for file %s = %d\n",
512                   fsp_str_dbg(fsp), lock_ref_count));
513
514         return lock_ref_count;
515 }
516
517 /****************************************************************************
518  Delete a lock_ref_count entry.
519 ****************************************************************************/
520
521 static void delete_windows_lock_ref_count(files_struct *fsp)
522 {
523         struct lock_ref_count_key tmp;
524         struct db_record *rec;
525
526         rec = posix_pending_close_db->fetch_locked(
527                 posix_pending_close_db, talloc_tos(),
528                 locking_ref_count_key_fsp(fsp, &tmp));
529
530         SMB_ASSERT(rec != NULL);
531
532         /* Not a bug if it doesn't exist - no locks were ever granted. */
533
534         rec->delete_rec(rec);
535         TALLOC_FREE(rec);
536
537         DEBUG(10,("delete_windows_lock_ref_count for file %s\n",
538                   fsp_str_dbg(fsp)));
539 }
540
541 /****************************************************************************
542  Add an fd to the pending close tdb.
543 ****************************************************************************/
544
545 static void add_fd_to_close_entry(files_struct *fsp)
546 {
547         struct db_record *rec;
548         uint8_t *new_data;
549         NTSTATUS status;
550
551         rec = posix_pending_close_db->fetch_locked(
552                 posix_pending_close_db, talloc_tos(),
553                 fd_array_key_fsp(fsp));
554
555         SMB_ASSERT(rec != NULL);
556
557         new_data = TALLOC_ARRAY(
558                 rec, uint8_t, rec->value.dsize + sizeof(fsp->fh->fd));
559
560         SMB_ASSERT(new_data != NULL);
561
562         memcpy(new_data, rec->value.dptr, rec->value.dsize);
563         memcpy(new_data + rec->value.dsize,
564                &fsp->fh->fd, sizeof(fsp->fh->fd));
565
566         status = rec->store(
567                 rec, make_tdb_data(new_data,
568                                    rec->value.dsize + sizeof(fsp->fh->fd)), 0);
569
570         SMB_ASSERT(NT_STATUS_IS_OK(status));
571
572         TALLOC_FREE(rec);
573
574         DEBUG(10,("add_fd_to_close_entry: added fd %d file %s\n",
575                   fsp->fh->fd, fsp_str_dbg(fsp)));
576 }
577
578 /****************************************************************************
579  Remove all fd entries for a specific dev/inode pair from the tdb.
580 ****************************************************************************/
581
582 static void delete_close_entries(files_struct *fsp)
583 {
584         struct db_record *rec;
585
586         rec = posix_pending_close_db->fetch_locked(
587                 posix_pending_close_db, talloc_tos(),
588                 fd_array_key_fsp(fsp));
589
590         SMB_ASSERT(rec != NULL);
591         rec->delete_rec(rec);
592         TALLOC_FREE(rec);
593 }
594
595 /****************************************************************************
596  Get the array of POSIX pending close records for an open fsp. Returns number
597  of entries.
598 ****************************************************************************/
599
600 static size_t get_posix_pending_close_entries(TALLOC_CTX *mem_ctx,
601                                               files_struct *fsp, int **entries)
602 {
603         TDB_DATA dbuf;
604         int res;
605
606         res = posix_pending_close_db->fetch(
607                 posix_pending_close_db, mem_ctx, fd_array_key_fsp(fsp),
608                 &dbuf);
609
610         SMB_ASSERT(res == 0);
611
612         if (dbuf.dsize == 0) {
613                 *entries = NULL;
614                 return 0;
615         }
616
617         *entries = (int *)dbuf.dptr;
618         return (size_t)(dbuf.dsize / sizeof(int));
619 }
620
621 /****************************************************************************
622  Deal with pending closes needed by POSIX locking support.
623  Note that posix_locking_close_file() is expected to have been called
624  to delete all locks on this fsp before this function is called.
625 ****************************************************************************/
626
627 int fd_close_posix(struct files_struct *fsp)
628 {
629         int saved_errno = 0;
630         int ret;
631         int *fd_array = NULL;
632         size_t count, i;
633
634         if (!lp_locking(fsp->conn->params) ||
635             !lp_posix_locking(fsp->conn->params))
636         {
637                 /*
638                  * No locking or POSIX to worry about or we want POSIX semantics
639                  * which will lose all locks on all fd's open on this dev/inode,
640                  * just close.
641                  */
642                 return close(fsp->fh->fd);
643         }
644
645         if (get_windows_lock_ref_count(fsp)) {
646
647                 /*
648                  * There are outstanding locks on this dev/inode pair on
649                  * other fds. Add our fd to the pending close tdb and set
650                  * fsp->fh->fd to -1.
651                  */
652
653                 add_fd_to_close_entry(fsp);
654                 return 0;
655         }
656
657         /*
658          * No outstanding locks. Get the pending close fd's
659          * from the tdb and close them all.
660          */
661
662         count = get_posix_pending_close_entries(talloc_tos(), fsp, &fd_array);
663
664         if (count) {
665                 DEBUG(10,("fd_close_posix: doing close on %u fd's.\n",
666                           (unsigned int)count));
667
668                 for(i = 0; i < count; i++) {
669                         if (close(fd_array[i]) == -1) {
670                                 saved_errno = errno;
671                         }
672                 }
673
674                 /*
675                  * Delete all fd's stored in the tdb
676                  * for this dev/inode pair.
677                  */
678
679                 delete_close_entries(fsp);
680         }
681
682         TALLOC_FREE(fd_array);
683
684         /* Don't need a lock ref count on this dev/ino anymore. */
685         delete_windows_lock_ref_count(fsp);
686
687         /*
688          * Finally close the fd associated with this fsp.
689          */
690
691         ret = close(fsp->fh->fd);
692
693         if (ret == 0 && saved_errno != 0) {
694                 errno = saved_errno;
695                 ret = -1;
696         }
697
698         return ret;
699 }
700
701 /****************************************************************************
702  Next - the functions that deal with the mapping CIFS Windows locks onto
703  the underlying system POSIX locks.
704 ****************************************************************************/
705
706 /*
707  * Structure used when splitting a lock range
708  * into a POSIX lock range. Doubly linked list.
709  */
710
711 struct lock_list {
712         struct lock_list *next;
713         struct lock_list *prev;
714         SMB_OFF_T start;
715         SMB_OFF_T size;
716 };
717
718 /****************************************************************************
719  Create a list of lock ranges that don't overlap a given range. Used in calculating
720  POSIX locks and unlocks. This is a difficult function that requires ASCII art to
721  understand it :-).
722 ****************************************************************************/
723
724 static struct lock_list *posix_lock_list(TALLOC_CTX *ctx,
725                                                 struct lock_list *lhead,
726                                                 const struct lock_context *lock_ctx, /* Lock context lhead belongs to. */
727                                                 files_struct *fsp,
728                                                 const struct lock_struct *plocks,
729                                                 int num_locks)
730 {
731         int i;
732
733         /*
734          * Check the current lock list on this dev/inode pair.
735          * Quit if the list is deleted.
736          */
737
738         DEBUG(10,("posix_lock_list: curr: start=%.0f,size=%.0f\n",
739                 (double)lhead->start, (double)lhead->size ));
740
741         for (i=0; i<num_locks && lhead; i++) {
742                 const struct lock_struct *lock = &plocks[i];
743                 struct lock_list *l_curr;
744
745                 /* Ignore all but read/write locks. */
746                 if (lock->lock_type != READ_LOCK && lock->lock_type != WRITE_LOCK) {
747                         continue;
748                 }
749
750                 /* Ignore locks not owned by this process. */
751                 if (!procid_equal(&lock->context.pid, &lock_ctx->pid)) {
752                         continue;
753                 }
754
755                 /*
756                  * Walk the lock list, checking for overlaps. Note that
757                  * the lock list can expand within this loop if the current
758                  * range being examined needs to be split.
759                  */
760
761                 for (l_curr = lhead; l_curr;) {
762
763                         DEBUG(10,("posix_lock_list: lock: fnum=%d: start=%.0f,size=%.0f:type=%s", lock->fnum,
764                                 (double)lock->start, (double)lock->size, posix_lock_type_name(lock->lock_type) ));
765
766                         if ( (l_curr->start >= (lock->start + lock->size)) ||
767                                  (lock->start >= (l_curr->start + l_curr->size))) {
768
769                                 /* No overlap with existing lock - leave this range alone. */
770 /*********************************************
771                                              +---------+
772                                              | l_curr  |
773                                              +---------+
774                                 +-------+
775                                 | lock  |
776                                 +-------+
777 OR....
778              +---------+
779              |  l_curr |
780              +---------+
781 **********************************************/
782
783                                 DEBUG(10,(" no overlap case.\n" ));
784
785                                 l_curr = l_curr->next;
786
787                         } else if ( (l_curr->start >= lock->start) &&
788                                                 (l_curr->start + l_curr->size <= lock->start + lock->size) ) {
789
790                                 /*
791                                  * This range is completely overlapped by this existing lock range
792                                  * and thus should have no effect. Delete it from the list.
793                                  */
794 /*********************************************
795                 +---------+
796                 |  l_curr |
797                 +---------+
798         +---------------------------+
799         |       lock                |
800         +---------------------------+
801 **********************************************/
802                                 /* Save the next pointer */
803                                 struct lock_list *ul_next = l_curr->next;
804
805                                 DEBUG(10,(" delete case.\n" ));
806
807                                 DLIST_REMOVE(lhead, l_curr);
808                                 if(lhead == NULL) {
809                                         break; /* No more list... */
810                                 }
811
812                                 l_curr = ul_next;
813                                 
814                         } else if ( (l_curr->start >= lock->start) &&
815                                                 (l_curr->start < lock->start + lock->size) &&
816                                                 (l_curr->start + l_curr->size > lock->start + lock->size) ) {
817
818                                 /*
819                                  * This range overlaps the existing lock range at the high end.
820                                  * Truncate by moving start to existing range end and reducing size.
821                                  */
822 /*********************************************
823                 +---------------+
824                 |  l_curr       |
825                 +---------------+
826         +---------------+
827         |    lock       |
828         +---------------+
829 BECOMES....
830                         +-------+
831                         | l_curr|
832                         +-------+
833 **********************************************/
834
835                                 l_curr->size = (l_curr->start + l_curr->size) - (lock->start + lock->size);
836                                 l_curr->start = lock->start + lock->size;
837
838                                 DEBUG(10,(" truncate high case: start=%.0f,size=%.0f\n",
839                                                                 (double)l_curr->start, (double)l_curr->size ));
840
841                                 l_curr = l_curr->next;
842
843                         } else if ( (l_curr->start < lock->start) &&
844                                                 (l_curr->start + l_curr->size > lock->start) &&
845                                                 (l_curr->start + l_curr->size <= lock->start + lock->size) ) {
846
847                                 /*
848                                  * This range overlaps the existing lock range at the low end.
849                                  * Truncate by reducing size.
850                                  */
851 /*********************************************
852    +---------------+
853    |  l_curr       |
854    +---------------+
855            +---------------+
856            |    lock       |
857            +---------------+
858 BECOMES....
859    +-------+
860    | l_curr|
861    +-------+
862 **********************************************/
863
864                                 l_curr->size = lock->start - l_curr->start;
865
866                                 DEBUG(10,(" truncate low case: start=%.0f,size=%.0f\n",
867                                                                 (double)l_curr->start, (double)l_curr->size ));
868
869                                 l_curr = l_curr->next;
870                 
871                         } else if ( (l_curr->start < lock->start) &&
872                                                 (l_curr->start + l_curr->size > lock->start + lock->size) ) {
873                                 /*
874                                  * Worst case scenario. Range completely overlaps an existing
875                                  * lock range. Split the request into two, push the new (upper) request
876                                  * into the dlink list, and continue with the entry after l_new (as we
877                                  * know that l_new will not overlap with this lock).
878                                  */
879 /*********************************************
880         +---------------------------+
881         |        l_curr             |
882         +---------------------------+
883                 +---------+
884                 | lock    |
885                 +---------+
886 BECOMES.....
887         +-------+         +---------+
888         | l_curr|         | l_new   |
889         +-------+         +---------+
890 **********************************************/
891                                 struct lock_list *l_new = TALLOC_P(ctx, struct lock_list);
892
893                                 if(l_new == NULL) {
894                                         DEBUG(0,("posix_lock_list: talloc fail.\n"));
895                                         return NULL; /* The talloc_destroy takes care of cleanup. */
896                                 }
897
898                                 ZERO_STRUCTP(l_new);
899                                 l_new->start = lock->start + lock->size;
900                                 l_new->size = l_curr->start + l_curr->size - l_new->start;
901
902                                 /* Truncate the l_curr. */
903                                 l_curr->size = lock->start - l_curr->start;
904
905                                 DEBUG(10,(" split case: curr: start=%.0f,size=%.0f \
906 new: start=%.0f,size=%.0f\n", (double)l_curr->start, (double)l_curr->size,
907                                                                 (double)l_new->start, (double)l_new->size ));
908
909                                 /*
910                                  * Add into the dlink list after the l_curr point - NOT at lhead. 
911                                  * Note we can't use DLINK_ADD here as this inserts at the head of the given list.
912                                  */
913
914                                 l_new->prev = l_curr;
915                                 l_new->next = l_curr->next;
916                                 l_curr->next = l_new;
917
918                                 /* And move after the link we added. */
919                                 l_curr = l_new->next;
920
921                         } else {
922
923                                 /*
924                                  * This logic case should never happen. Ensure this is the
925                                  * case by forcing an abort.... Remove in production.
926                                  */
927                                 char *msg = NULL;
928
929                                 if (asprintf(&msg, "logic flaw in cases: l_curr: start = %.0f, size = %.0f : \
930 lock: start = %.0f, size = %.0f", (double)l_curr->start, (double)l_curr->size, (double)lock->start, (double)lock->size ) != -1) {
931                                         smb_panic(msg);
932                                 } else {
933                                         smb_panic("posix_lock_list");
934                                 }
935                         }
936                 } /* end for ( l_curr = lhead; l_curr;) */
937         } /* end for (i=0; i<num_locks && ul_head; i++) */
938
939         return lhead;
940 }
941
942 /****************************************************************************
943  POSIX function to acquire a lock. Returns True if the
944  lock could be granted, False if not.
945 ****************************************************************************/
946
947 bool set_posix_lock_windows_flavour(files_struct *fsp,
948                         uint64_t u_offset,
949                         uint64_t u_count,
950                         enum brl_type lock_type,
951                         const struct lock_context *lock_ctx,
952                         const struct lock_struct *plocks,
953                         int num_locks,
954                         int *errno_ret)
955 {
956         SMB_OFF_T offset;
957         SMB_OFF_T count;
958         int posix_lock_type = map_posix_lock_type(fsp,lock_type);
959         bool ret = True;
960         size_t lock_count;
961         TALLOC_CTX *l_ctx = NULL;
962         struct lock_list *llist = NULL;
963         struct lock_list *ll = NULL;
964
965         DEBUG(5,("set_posix_lock_windows_flavour: File %s, offset = %.0f, "
966                  "count = %.0f, type = %s\n", fsp_str_dbg(fsp),
967                  (double)u_offset, (double)u_count,
968                  posix_lock_type_name(lock_type)));
969
970         /*
971          * If the requested lock won't fit in the POSIX range, we will
972          * pretend it was successful.
973          */
974
975         if(!posix_lock_in_range(&offset, &count, u_offset, u_count)) {
976                 increment_windows_lock_ref_count(fsp);
977                 return True;
978         }
979
980         /*
981          * Windows is very strange. It allows read locks to be overlayed
982          * (even over a write lock), but leaves the write lock in force until the first
983          * unlock. It also reference counts the locks. This means the following sequence :
984          *
985          * process1                                      process2
986          * ------------------------------------------------------------------------
987          * WRITE LOCK : start = 2, len = 10
988          *                                            READ LOCK: start =0, len = 10 - FAIL
989          * READ LOCK : start = 0, len = 14 
990          *                                            READ LOCK: start =0, len = 10 - FAIL
991          * UNLOCK : start = 2, len = 10
992          *                                            READ LOCK: start =0, len = 10 - OK
993          *
994          * Under POSIX, the same sequence in steps 1 and 2 would not be reference counted, but
995          * would leave a single read lock over the 0-14 region.
996          */
997         
998         if ((l_ctx = talloc_init("set_posix_lock")) == NULL) {
999                 DEBUG(0,("set_posix_lock_windows_flavour: unable to init talloc context.\n"));
1000                 return False;
1001         }
1002
1003         if ((ll = TALLOC_P(l_ctx, struct lock_list)) == NULL) {
1004                 DEBUG(0,("set_posix_lock_windows_flavour: unable to talloc unlock list.\n"));
1005                 talloc_destroy(l_ctx);
1006                 return False;
1007         }
1008
1009         /*
1010          * Create the initial list entry containing the
1011          * lock we want to add.
1012          */
1013
1014         ZERO_STRUCTP(ll);
1015         ll->start = offset;
1016         ll->size = count;
1017
1018         DLIST_ADD(llist, ll);
1019
1020         /*
1021          * The following call calculates if there are any
1022          * overlapping locks held by this process on
1023          * fd's open on the same file and splits this list
1024          * into a list of lock ranges that do not overlap with existing
1025          * POSIX locks.
1026          */
1027
1028         llist = posix_lock_list(l_ctx,
1029                                 llist,
1030                                 lock_ctx, /* Lock context llist belongs to. */
1031                                 fsp,
1032                                 plocks,
1033                                 num_locks);
1034
1035         /*
1036          * Add the POSIX locks on the list of ranges returned.
1037          * As the lock is supposed to be added atomically, we need to
1038          * back out all the locks if any one of these calls fail.
1039          */
1040
1041         for (lock_count = 0, ll = llist; ll; ll = ll->next, lock_count++) {
1042                 offset = ll->start;
1043                 count = ll->size;
1044
1045                 DEBUG(5,("set_posix_lock_windows_flavour: Real lock: Type = %s: offset = %.0f, count = %.0f\n",
1046                         posix_lock_type_name(posix_lock_type), (double)offset, (double)count ));
1047
1048                 if (!posix_fcntl_lock(fsp,SMB_F_SETLK,offset,count,posix_lock_type)) {
1049                         *errno_ret = errno;
1050                         DEBUG(5,("set_posix_lock_windows_flavour: Lock fail !: Type = %s: offset = %.0f, count = %.0f. Errno = %s\n",
1051                                 posix_lock_type_name(posix_lock_type), (double)offset, (double)count, strerror(errno) ));
1052                         ret = False;
1053                         break;
1054                 }
1055         }
1056
1057         if (!ret) {
1058
1059                 /*
1060                  * Back out all the POSIX locks we have on fail.
1061                  */
1062
1063                 for (ll = llist; lock_count; ll = ll->next, lock_count--) {
1064                         offset = ll->start;
1065                         count = ll->size;
1066
1067                         DEBUG(5,("set_posix_lock_windows_flavour: Backing out locks: Type = %s: offset = %.0f, count = %.0f\n",
1068                                 posix_lock_type_name(posix_lock_type), (double)offset, (double)count ));
1069
1070                         posix_fcntl_lock(fsp,SMB_F_SETLK,offset,count,F_UNLCK);
1071                 }
1072         } else {
1073                 /* Remember the number of Windows locks we have on this dev/ino pair. */
1074                 increment_windows_lock_ref_count(fsp);
1075         }
1076
1077         talloc_destroy(l_ctx);
1078         return ret;
1079 }
1080
1081 /****************************************************************************
1082  POSIX function to release a lock. Returns True if the
1083  lock could be released, False if not.
1084 ****************************************************************************/
1085
1086 bool release_posix_lock_windows_flavour(files_struct *fsp,
1087                                 uint64_t u_offset,
1088                                 uint64_t u_count,
1089                                 enum brl_type deleted_lock_type,
1090                                 const struct lock_context *lock_ctx,
1091                                 const struct lock_struct *plocks,
1092                                 int num_locks)
1093 {
1094         SMB_OFF_T offset;
1095         SMB_OFF_T count;
1096         bool ret = True;
1097         TALLOC_CTX *ul_ctx = NULL;
1098         struct lock_list *ulist = NULL;
1099         struct lock_list *ul = NULL;
1100
1101         DEBUG(5,("release_posix_lock_windows_flavour: File %s, offset = %.0f, "
1102                  "count = %.0f\n", fsp_str_dbg(fsp),
1103                  (double)u_offset, (double)u_count));
1104
1105         /* Remember the number of Windows locks we have on this dev/ino pair. */
1106         decrement_windows_lock_ref_count(fsp);
1107
1108         /*
1109          * If the requested lock won't fit in the POSIX range, we will
1110          * pretend it was successful.
1111          */
1112
1113         if(!posix_lock_in_range(&offset, &count, u_offset, u_count)) {
1114                 return True;
1115         }
1116
1117         if ((ul_ctx = talloc_init("release_posix_lock")) == NULL) {
1118                 DEBUG(0,("release_posix_lock_windows_flavour: unable to init talloc context.\n"));
1119                 return False;
1120         }
1121
1122         if ((ul = TALLOC_P(ul_ctx, struct lock_list)) == NULL) {
1123                 DEBUG(0,("release_posix_lock_windows_flavour: unable to talloc unlock list.\n"));
1124                 talloc_destroy(ul_ctx);
1125                 return False;
1126         }
1127
1128         /*
1129          * Create the initial list entry containing the
1130          * lock we want to remove.
1131          */
1132
1133         ZERO_STRUCTP(ul);
1134         ul->start = offset;
1135         ul->size = count;
1136
1137         DLIST_ADD(ulist, ul);
1138
1139         /*
1140          * The following call calculates if there are any
1141          * overlapping locks held by this process on
1142          * fd's open on the same file and creates a
1143          * list of unlock ranges that will allow
1144          * POSIX lock ranges to remain on the file whilst the
1145          * unlocks are performed.
1146          */
1147
1148         ulist = posix_lock_list(ul_ctx,
1149                                 ulist,
1150                                 lock_ctx, /* Lock context ulist belongs to. */
1151                                 fsp,
1152                                 plocks,
1153                                 num_locks);
1154
1155         /*
1156          * If there were any overlapped entries (list is > 1 or size or start have changed),
1157          * and the lock_type we just deleted from
1158          * the upper layer tdb was a write lock, then before doing the unlock we need to downgrade
1159          * the POSIX lock to a read lock. This allows any overlapping read locks
1160          * to be atomically maintained.
1161          */
1162
1163         if (deleted_lock_type == WRITE_LOCK &&
1164                         (!ulist || ulist->next != NULL || ulist->start != offset || ulist->size != count)) {
1165
1166                 DEBUG(5,("release_posix_lock_windows_flavour: downgrading lock to READ: offset = %.0f, count = %.0f\n",
1167                         (double)offset, (double)count ));
1168
1169                 if (!posix_fcntl_lock(fsp,SMB_F_SETLK,offset,count,F_RDLCK)) {
1170                         DEBUG(0,("release_posix_lock_windows_flavour: downgrade of lock failed with error %s !\n", strerror(errno) ));
1171                         talloc_destroy(ul_ctx);
1172                         return False;
1173                 }
1174         }
1175
1176         /*
1177          * Release the POSIX locks on the list of ranges returned.
1178          */
1179
1180         for(; ulist; ulist = ulist->next) {
1181                 offset = ulist->start;
1182                 count = ulist->size;
1183
1184                 DEBUG(5,("release_posix_lock_windows_flavour: Real unlock: offset = %.0f, count = %.0f\n",
1185                         (double)offset, (double)count ));
1186
1187                 if (!posix_fcntl_lock(fsp,SMB_F_SETLK,offset,count,F_UNLCK)) {
1188                         ret = False;
1189                 }
1190         }
1191
1192         talloc_destroy(ul_ctx);
1193         return ret;
1194 }
1195
1196 /****************************************************************************
1197  Next - the functions that deal with mapping CIFS POSIX locks onto
1198  the underlying system POSIX locks.
1199 ****************************************************************************/
1200
1201 /****************************************************************************
1202  POSIX function to acquire a lock. Returns True if the
1203  lock could be granted, False if not.
1204  As POSIX locks don't stack or conflict (they just overwrite)
1205  we can map the requested lock directly onto a system one. We
1206  know it doesn't conflict with locks on other contexts as the
1207  upper layer would have refused it.
1208 ****************************************************************************/
1209
1210 bool set_posix_lock_posix_flavour(files_struct *fsp,
1211                         uint64_t u_offset,
1212                         uint64_t u_count,
1213                         enum brl_type lock_type,
1214                         int *errno_ret)
1215 {
1216         SMB_OFF_T offset;
1217         SMB_OFF_T count;
1218         int posix_lock_type = map_posix_lock_type(fsp,lock_type);
1219
1220         DEBUG(5,("set_posix_lock_posix_flavour: File %s, offset = %.0f, count "
1221                  "= %.0f, type = %s\n", fsp_str_dbg(fsp),
1222                  (double)u_offset, (double)u_count,
1223                  posix_lock_type_name(lock_type)));
1224
1225         /*
1226          * If the requested lock won't fit in the POSIX range, we will
1227          * pretend it was successful.
1228          */
1229
1230         if(!posix_lock_in_range(&offset, &count, u_offset, u_count)) {
1231                 return True;
1232         }
1233
1234         if (!posix_fcntl_lock(fsp,SMB_F_SETLK,offset,count,posix_lock_type)) {
1235                 *errno_ret = errno;
1236                 DEBUG(5,("set_posix_lock_posix_flavour: Lock fail !: Type = %s: offset = %.0f, count = %.0f. Errno = %s\n",
1237                         posix_lock_type_name(posix_lock_type), (double)offset, (double)count, strerror(errno) ));
1238                 return False;
1239         }
1240         return True;
1241 }
1242
1243 /****************************************************************************
1244  POSIX function to release a lock. Returns True if the
1245  lock could be released, False if not.
1246  We are given a complete lock state from the upper layer which is what the lock
1247  state should be after the unlock has already been done, so what
1248  we do is punch out holes in the unlock range where locks owned by this process
1249  have a different lock context.
1250 ****************************************************************************/
1251
1252 bool release_posix_lock_posix_flavour(files_struct *fsp,
1253                                 uint64_t u_offset,
1254                                 uint64_t u_count,
1255                                 const struct lock_context *lock_ctx,
1256                                 const struct lock_struct *plocks,
1257                                 int num_locks)
1258 {
1259         bool ret = True;
1260         SMB_OFF_T offset;
1261         SMB_OFF_T count;
1262         TALLOC_CTX *ul_ctx = NULL;
1263         struct lock_list *ulist = NULL;
1264         struct lock_list *ul = NULL;
1265
1266         DEBUG(5,("release_posix_lock_posix_flavour: File %s, offset = %.0f, "
1267                  "count = %.0f\n", fsp_str_dbg(fsp),
1268                  (double)u_offset, (double)u_count));
1269
1270         /*
1271          * If the requested lock won't fit in the POSIX range, we will
1272          * pretend it was successful.
1273          */
1274
1275         if(!posix_lock_in_range(&offset, &count, u_offset, u_count)) {
1276                 return True;
1277         }
1278
1279         if ((ul_ctx = talloc_init("release_posix_lock")) == NULL) {
1280                 DEBUG(0,("release_posix_lock_windows_flavour: unable to init talloc context.\n"));
1281                 return False;
1282         }
1283
1284         if ((ul = TALLOC_P(ul_ctx, struct lock_list)) == NULL) {
1285                 DEBUG(0,("release_posix_lock_windows_flavour: unable to talloc unlock list.\n"));
1286                 talloc_destroy(ul_ctx);
1287                 return False;
1288         }
1289
1290         /*
1291          * Create the initial list entry containing the
1292          * lock we want to remove.
1293          */
1294
1295         ZERO_STRUCTP(ul);
1296         ul->start = offset;
1297         ul->size = count;
1298
1299         DLIST_ADD(ulist, ul);
1300
1301         /*
1302          * Walk the given array creating a linked list
1303          * of unlock requests.
1304          */
1305
1306         ulist = posix_lock_list(ul_ctx,
1307                                 ulist,
1308                                 lock_ctx, /* Lock context ulist belongs to. */
1309                                 fsp,
1310                                 plocks,
1311                                 num_locks);
1312
1313         /*
1314          * Release the POSIX locks on the list of ranges returned.
1315          */
1316
1317         for(; ulist; ulist = ulist->next) {
1318                 offset = ulist->start;
1319                 count = ulist->size;
1320
1321                 DEBUG(5,("release_posix_lock_posix_flavour: Real unlock: offset = %.0f, count = %.0f\n",
1322                         (double)offset, (double)count ));
1323
1324                 if (!posix_fcntl_lock(fsp,SMB_F_SETLK,offset,count,F_UNLCK)) {
1325                         ret = False;
1326                 }
1327         }
1328
1329         talloc_destroy(ul_ctx);
1330         return ret;
1331 }