Fix bug #6520 time stamps - e.g. last mod time is not preserved when "unix extensions...
[ira/wip.git] / source3 / smbd / fileio.c
1 /* 
2    Unix SMB/Netbios implementation.
3    Version 1.9.
4    read/write to a files_struct
5    Copyright (C) Andrew Tridgell 1992-1998
6    Copyright (C) Jeremy Allison 2000-2002. - write cache.
7    
8    This program is free software; you can redistribute it and/or modify
9    it under the terms of the GNU General Public License as published by
10    the Free Software Foundation; either version 3 of the License, or
11    (at your option) any later version.
12    
13    This program is distributed in the hope that it will be useful,
14    but WITHOUT ANY WARRANTY; without even the implied warranty of
15    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
16    GNU General Public License for more details.
17    
18    You should have received a copy of the GNU General Public License
19    along with this program.  If not, see <http://www.gnu.org/licenses/>.
20 */
21
22 #include "includes.h"
23 #include "smbd/globals.h"
24
25 static bool setup_write_cache(files_struct *, SMB_OFF_T);
26
27 /****************************************************************************
28  Read from write cache if we can.
29 ****************************************************************************/
30
31 static bool read_from_write_cache(files_struct *fsp,char *data,SMB_OFF_T pos,size_t n)
32 {
33         write_cache *wcp = fsp->wcp;
34
35         if(!wcp) {
36                 return False;
37         }
38
39         if( n > wcp->data_size || pos < wcp->offset || pos + n > wcp->offset + wcp->data_size) {
40                 return False;
41         }
42
43         memcpy(data, wcp->data + (pos - wcp->offset), n);
44
45         DO_PROFILE_INC(writecache_read_hits);
46
47         return True;
48 }
49
50 /****************************************************************************
51  Read from a file.
52 ****************************************************************************/
53
54 ssize_t read_file(files_struct *fsp,char *data,SMB_OFF_T pos,size_t n)
55 {
56         ssize_t ret=0,readret;
57
58         /* you can't read from print files */
59         if (fsp->print_file) {
60                 return -1;
61         }
62
63         /*
64          * Serve from write cache if we can.
65          */
66
67         if(read_from_write_cache(fsp, data, pos, n)) {
68                 fsp->fh->pos = pos + n;
69                 fsp->fh->position_information = fsp->fh->pos;
70                 return n;
71         }
72
73         flush_write_cache(fsp, READ_FLUSH);
74
75         fsp->fh->pos = pos;
76
77         if (n > 0) {
78 #ifdef DMF_FIX
79                 int numretries = 3;
80 tryagain:
81                 readret = SMB_VFS_PREAD(fsp,data,n,pos);
82
83                 if (readret == -1) {
84                         if ((errno == EAGAIN) && numretries) {
85                                 DEBUG(3,("read_file EAGAIN retry in 10 seconds\n"));
86                                 (void)sleep(10);
87                                 --numretries;
88                                 goto tryagain;
89                         }
90                         return -1;
91                 }
92 #else /* NO DMF fix. */
93                 readret = SMB_VFS_PREAD(fsp,data,n,pos);
94
95                 if (readret == -1) {
96                         return -1;
97                 }
98 #endif
99                 if (readret > 0) {
100                         ret += readret;
101                 }
102         }
103
104         DEBUG(10,("read_file (%s): pos = %.0f, size = %lu, returned %lu\n",
105                 fsp->fsp_name, (double)pos, (unsigned long)n, (long)ret ));
106
107         fsp->fh->pos += ret;
108         fsp->fh->position_information = fsp->fh->pos;
109
110         return(ret);
111 }
112
113 /****************************************************************************
114  *Really* write to a file.
115 ****************************************************************************/
116
117 static ssize_t real_write_file(struct smb_request *req,
118                                 files_struct *fsp,
119                                 const char *data,
120                                 SMB_OFF_T pos,
121                                 size_t n)
122 {
123         ssize_t ret;
124
125         if (pos == -1) {
126                 ret = vfs_write_data(req, fsp, data, n);
127         } else {
128                 fsp->fh->pos = pos;
129                 if (pos && lp_strict_allocate(SNUM(fsp->conn))) {
130                         if (vfs_fill_sparse(fsp, pos) == -1) {
131                                 return -1;
132                         }
133                 }
134                 ret = vfs_pwrite_data(req, fsp, data, n, pos);
135         }
136
137         DEBUG(10,("real_write_file (%s): pos = %.0f, size = %lu, returned %ld\n",
138                 fsp->fsp_name, (double)pos, (unsigned long)n, (long)ret ));
139
140         if (ret != -1) {
141                 fsp->fh->pos += ret;
142
143 /* Yes - this is correct - writes don't update this. JRA. */
144 /* Found by Samba4 tests. */
145 #if 0
146                 fsp->position_information = fsp->pos;
147 #endif
148         }
149
150         return ret;
151 }
152
153 /****************************************************************************
154  File size cache change.
155  Updates size on disk but doesn't flush the cache.
156 ****************************************************************************/
157
158 static int wcp_file_size_change(files_struct *fsp)
159 {
160         int ret;
161         write_cache *wcp = fsp->wcp;
162
163         wcp->file_size = wcp->offset + wcp->data_size;
164         ret = SMB_VFS_FTRUNCATE(fsp, wcp->file_size);
165         if (ret == -1) {
166                 DEBUG(0,("wcp_file_size_change (%s): ftruncate of size %.0f error %s\n",
167                         fsp->fsp_name, (double)wcp->file_size, strerror(errno) ));
168         }
169         return ret;
170 }
171
172 static void update_write_time_handler(struct event_context *ctx,
173                                       struct timed_event *te,
174                                       struct timeval now,
175                                       void *private_data)
176 {
177         files_struct *fsp = (files_struct *)private_data;
178
179         /* Remove the timed event handler. */
180         TALLOC_FREE(fsp->update_write_time_event);
181         DEBUG(5, ("Update write time on %s\n", fsp->fsp_name));
182
183         /* change the write time if not already changed by someone else */
184         update_write_time(fsp);
185 }
186
187 /*********************************************************
188  Schedule a write time update for WRITE_TIME_UPDATE_USEC_DELAY
189  in the future.
190 *********************************************************/
191
192 void trigger_write_time_update(struct files_struct *fsp)
193 {
194         int delay;
195
196         if (fsp->write_time_forced) {
197                 /* No point - "sticky" write times
198                  * in effect.
199                  */
200                 return;
201         }
202
203         if (fsp->update_write_time_triggered) {
204                 /*
205                  * We only update the write time
206                  * on the first write. After that
207                  * no other writes affect this.
208                  */
209                 return;
210         }
211         fsp->update_write_time_triggered = true;
212
213         delay = lp_parm_int(SNUM(fsp->conn),
214                             "smbd", "writetimeupdatedelay",
215                             WRITE_TIME_UPDATE_USEC_DELAY);
216
217         /* trigger the update 2 seconds later */
218         fsp->update_write_time_on_close = true;
219         fsp->update_write_time_event =
220                 event_add_timed(smbd_event_context(), NULL,
221                                 timeval_current_ofs(0, delay),
222                                 update_write_time_handler, fsp);
223 }
224
225 void trigger_write_time_update_immediate(struct files_struct *fsp)
226 {
227         if (fsp->write_time_forced) {
228                 /*
229                  * No point - "sticky" write times
230                  * in effect.
231                  */
232                 return;
233         }
234
235         TALLOC_FREE(fsp->update_write_time_event);
236         DEBUG(5, ("Update write time immediate on %s\n", fsp->fsp_name));
237
238         fsp->update_write_time_triggered = true;
239
240         fsp->update_write_time_on_close = false;
241         update_write_time(fsp);
242 }
243
244 /****************************************************************************
245  Write to a file.
246 ****************************************************************************/
247
248 ssize_t write_file(struct smb_request *req,
249                         files_struct *fsp,
250                         const char *data,
251                         SMB_OFF_T pos,
252                         size_t n)
253 {
254         write_cache *wcp = fsp->wcp;
255         ssize_t total_written = 0;
256         int write_path = -1;
257
258         if (fsp->print_file) {
259                 uint32 jobid;
260
261                 if (!rap_to_pjobid(fsp->rap_print_jobid, NULL, &jobid)) {
262                         DEBUG(3,("write_file: Unable to map RAP jobid %u to jobid.\n",
263                                                 (unsigned int)fsp->rap_print_jobid ));
264                         errno = EBADF;
265                         return -1;
266                 }
267
268                 return print_job_write(SNUM(fsp->conn), jobid, data, pos, n);
269         }
270
271         if (!fsp->can_write) {
272                 errno = EPERM;
273                 return -1;
274         }
275
276         if (!fsp->modified) {
277                 SMB_STRUCT_STAT st;
278                 fsp->modified = True;
279
280                 if (SMB_VFS_FSTAT(fsp, &st) == 0) {
281                         int dosmode;
282                         trigger_write_time_update(fsp);
283                         dosmode = dos_mode(fsp->conn,fsp->fsp_name,&st);
284                         if ((lp_store_dos_attributes(SNUM(fsp->conn)) ||
285                                         MAP_ARCHIVE(fsp->conn)) &&
286                                         !IS_DOS_ARCHIVE(dosmode)) {
287                                 file_set_dosmode(fsp->conn,fsp->fsp_name,
288                                                 dosmode | aARCH,&st,
289                                                 NULL,
290                                                 false);
291                         }
292
293                         /*
294                          * If this is the first write and we have an exclusive oplock then setup
295                          * the write cache.
296                          */
297
298                         if (EXCLUSIVE_OPLOCK_TYPE(fsp->oplock_type) && !wcp) {
299                                 setup_write_cache(fsp, st.st_ex_size);
300                                 wcp = fsp->wcp;
301                         }
302                 }
303         }
304
305 #ifdef WITH_PROFILE
306         DO_PROFILE_INC(writecache_total_writes);
307         if (!fsp->oplock_type) {
308                 DO_PROFILE_INC(writecache_non_oplock_writes);
309         }
310 #endif
311
312         /*
313          * If this file is level II oplocked then we need
314          * to grab the shared memory lock and inform all
315          * other files with a level II lock that they need
316          * to flush their read caches. We keep the lock over
317          * the shared memory area whilst doing this.
318          */
319
320         /* This should actually be improved to span the write. */
321         contend_level2_oplocks_begin(fsp, LEVEL2_CONTEND_WRITE);
322         contend_level2_oplocks_end(fsp, LEVEL2_CONTEND_WRITE);
323
324 #ifdef WITH_PROFILE
325         if (profile_p && profile_p->writecache_total_writes % 500 == 0) {
326                 DEBUG(3,("WRITECACHE: initwrites=%u abutted=%u total=%u \
327 nonop=%u allocated=%u active=%u direct=%u perfect=%u readhits=%u\n",
328                         profile_p->writecache_init_writes,
329                         profile_p->writecache_abutted_writes,
330                         profile_p->writecache_total_writes,
331                         profile_p->writecache_non_oplock_writes,
332                         profile_p->writecache_allocated_write_caches,
333                         profile_p->writecache_num_write_caches,
334                         profile_p->writecache_direct_writes,
335                         profile_p->writecache_num_perfect_writes,
336                         profile_p->writecache_read_hits ));
337
338                 DEBUG(3,("WRITECACHE: Flushes SEEK=%d, READ=%d, WRITE=%d, READRAW=%d, OPLOCK=%d, CLOSE=%d, SYNC=%d\n",
339                         profile_p->writecache_flushed_writes[SEEK_FLUSH],
340                         profile_p->writecache_flushed_writes[READ_FLUSH],
341                         profile_p->writecache_flushed_writes[WRITE_FLUSH],
342                         profile_p->writecache_flushed_writes[READRAW_FLUSH],
343                         profile_p->writecache_flushed_writes[OPLOCK_RELEASE_FLUSH],
344                         profile_p->writecache_flushed_writes[CLOSE_FLUSH],
345                         profile_p->writecache_flushed_writes[SYNC_FLUSH] ));
346         }
347 #endif
348
349         if (wcp && req->unread_bytes) {
350                 /* If we're using receivefile don't
351                  * deal with a write cache.
352                  */
353                 flush_write_cache(fsp, WRITE_FLUSH);
354                 delete_write_cache(fsp);
355                 wcp = NULL;
356         }
357
358         if(!wcp) {
359                 DO_PROFILE_INC(writecache_direct_writes);
360                 total_written = real_write_file(req, fsp, data, pos, n);
361                 return total_written;
362         }
363
364         DEBUG(9,("write_file (%s)(fd=%d pos=%.0f size=%u) wcp->offset=%.0f wcp->data_size=%u\n",
365                 fsp->fsp_name, fsp->fh->fd, (double)pos, (unsigned int)n, (double)wcp->offset, (unsigned int)wcp->data_size));
366
367         fsp->fh->pos = pos + n;
368
369         /*
370          * If we have active cache and it isn't contiguous then we flush.
371          * NOTE: There is a small problem with running out of disk ....
372          */
373
374         if (wcp->data_size) {
375                 bool cache_flush_needed = False;
376
377                 if ((pos >= wcp->offset) && (pos <= wcp->offset + wcp->data_size)) {
378       
379                         /* ASCII art.... JRA.
380
381       +--------------+-----
382       | Cached data  | Rest of allocated cache buffer....
383       +--------------+-----
384
385             +-------------------+
386             | Data to write     |
387             +-------------------+
388
389                         */
390
391                         /*
392                          * Start of write overlaps or abutts the existing data.
393                          */
394
395                         size_t data_used = MIN((wcp->alloc_size - (pos - wcp->offset)), n);
396
397                         memcpy(wcp->data + (pos - wcp->offset), data, data_used);
398
399                         /*
400                          * Update the current buffer size with the new data.
401                          */
402
403                         if(pos + data_used > wcp->offset + wcp->data_size) {
404                                 wcp->data_size = pos + data_used - wcp->offset;
405                         }
406
407                         /*
408                          * Update the file size if changed.
409                          */
410
411                         if (wcp->offset + wcp->data_size > wcp->file_size) {
412                                 if (wcp_file_size_change(fsp) == -1) {
413                                         return -1;
414                                 }
415                         }
416
417                         /*
418                          * If we used all the data then
419                          * return here.
420                          */
421
422                         if(n == data_used) {
423                                 return n;
424                         } else {
425                                 cache_flush_needed = True;
426                         }
427                         /*
428                          * Move the start of data forward by the amount used,
429                          * cut down the amount left by the same amount.
430                          */
431
432                         data += data_used;
433                         pos += data_used;
434                         n -= data_used;
435
436                         DO_PROFILE_INC(writecache_abutted_writes);
437                         total_written = data_used;
438
439                         write_path = 1;
440
441                 } else if ((pos < wcp->offset) && (pos + n > wcp->offset) && 
442                                         (pos + n <= wcp->offset + wcp->alloc_size)) {
443
444                         /* ASCII art.... JRA.
445
446                         +---------------+
447                         | Cache buffer  |
448                         +---------------+
449
450             +-------------------+
451             | Data to write     |
452             +-------------------+
453
454                         */
455
456                         /*
457                          * End of write overlaps the existing data.
458                          */
459
460                         size_t data_used = pos + n - wcp->offset;
461
462                         memcpy(wcp->data, data + n - data_used, data_used);
463
464                         /*
465                          * Update the current buffer size with the new data.
466                          */
467
468                         if(pos + n > wcp->offset + wcp->data_size) {
469                                 wcp->data_size = pos + n - wcp->offset;
470                         }
471
472                         /*
473                          * Update the file size if changed.
474                          */
475
476                         if (wcp->offset + wcp->data_size > wcp->file_size) {
477                                 if (wcp_file_size_change(fsp) == -1) {
478                                         return -1;
479                                 }
480                         }
481
482                         /*
483                          * We don't need to move the start of data, but we
484                          * cut down the amount left by the amount used.
485                          */
486
487                         n -= data_used;
488
489                         /*
490                          * We cannot have used all the data here.
491                          */
492
493                         cache_flush_needed = True;
494
495                         DO_PROFILE_INC(writecache_abutted_writes);
496                         total_written = data_used;
497
498                         write_path = 2;
499
500                 } else if ( (pos >= wcp->file_size) && 
501                                         (wcp->offset + wcp->data_size == wcp->file_size) &&
502                                         (pos > wcp->offset + wcp->data_size) && 
503                                         (pos < wcp->offset + wcp->alloc_size) ) {
504
505                         /* ASCII art.... JRA.
506
507                        End of file ---->|
508
509                         +---------------+---------------+
510                         | Cached data   | Cache buffer  |
511                         +---------------+---------------+
512
513                                               +-------------------+
514                                               | Data to write     |
515                                               +-------------------+
516
517                         */
518
519                         /*
520                          * Non-contiguous write part of which fits within
521                          * the cache buffer and is extending the file
522                          * and the cache contents reflect the current
523                          * data up to the current end of the file.
524                          */
525
526                         size_t data_used;
527
528                         if(pos + n <= wcp->offset + wcp->alloc_size) {
529                                 data_used = n;
530                         } else {
531                                 data_used = wcp->offset + wcp->alloc_size - pos;
532                         }
533
534                         /*
535                          * Fill in the non-continuous area with zeros.
536                          */
537
538                         memset(wcp->data + wcp->data_size, '\0',
539                                 pos - (wcp->offset + wcp->data_size) );
540
541                         memcpy(wcp->data + (pos - wcp->offset), data, data_used);
542
543                         /*
544                          * Update the current buffer size with the new data.
545                          */
546
547                         if(pos + data_used > wcp->offset + wcp->data_size) {
548                                 wcp->data_size = pos + data_used - wcp->offset;
549                         }
550
551                         /*
552                          * Update the file size if changed.
553                          */
554
555                         if (wcp->offset + wcp->data_size > wcp->file_size) {
556                                 if (wcp_file_size_change(fsp) == -1) {
557                                         return -1;
558                                 }
559                         }
560
561                         /*
562                          * If we used all the data then
563                          * return here.
564                          */
565
566                         if(n == data_used) {
567                                 return n;
568                         } else {
569                                 cache_flush_needed = True;
570                         }
571
572                         /*
573                          * Move the start of data forward by the amount used,
574                          * cut down the amount left by the same amount.
575                          */
576
577                         data += data_used;
578                         pos += data_used;
579                         n -= data_used;
580
581                         DO_PROFILE_INC(writecache_abutted_writes);
582                         total_written = data_used;
583
584                         write_path = 3;
585
586                 } else if ( (pos >= wcp->file_size) &&
587                             (n == 1) &&
588                             (wcp->file_size == wcp->offset + wcp->data_size) &&
589                             (pos < wcp->file_size + wcp->alloc_size)) {
590
591                         /*
592
593                 End of file ---->|
594
595                  +---------------+---------------+
596                  | Cached data   | Cache buffer  |
597                  +---------------+---------------+
598
599                                  |<------- allocated size ---------------->|
600
601                                                          +--------+
602                                                          | 1 Byte |
603                                                          +--------+
604
605                         MS-Office seems to do this a lot to determine if there's enough
606                         space on the filesystem to write a new file.
607
608                         Change to :
609
610                 End of file ---->|
611                                  +-----------------------+--------+
612                                  | Zeroed Cached data    | 1 Byte |
613                                  +-----------------------+--------+
614                         */
615
616                         flush_write_cache(fsp, WRITE_FLUSH);
617                         wcp->offset = wcp->file_size;
618                         wcp->data_size = pos - wcp->file_size + 1;
619                         memset(wcp->data, '\0', wcp->data_size);
620                         memcpy(wcp->data + wcp->data_size-1, data, 1);
621
622                         /*
623                          * Update the file size if changed.
624                          */
625
626                         if (wcp->offset + wcp->data_size > wcp->file_size) {
627                                 if (wcp_file_size_change(fsp) == -1) {
628                                         return -1;
629                                 }
630                         }
631
632                         return n;
633
634                 } else {
635
636                         /* ASCII art..... JRA.
637
638    Case 1).
639
640                         +---------------+---------------+
641                         | Cached data   | Cache buffer  |
642                         +---------------+---------------+
643
644                                                               +-------------------+
645                                                               | Data to write     |
646                                                               +-------------------+
647
648    Case 2).
649
650                            +---------------+---------------+
651                            | Cached data   | Cache buffer  |
652                            +---------------+---------------+
653
654    +-------------------+
655    | Data to write     |
656    +-------------------+
657
658     Case 3).
659
660                            +---------------+---------------+
661                            | Cached data   | Cache buffer  |
662                            +---------------+---------------+
663
664                   +-----------------------------------------------------+
665                   | Data to write                                       |
666                   +-----------------------------------------------------+
667
668                   */
669
670                         /*
671                          * Write is bigger than buffer, or there is no overlap on the
672                          * low or high ends.
673                          */
674
675                         DEBUG(9,("write_file: non cacheable write : fd = %d, pos = %.0f, len = %u, current cache pos = %.0f \
676 len = %u\n",fsp->fh->fd, (double)pos, (unsigned int)n, (double)wcp->offset, (unsigned int)wcp->data_size ));
677
678                         /*
679                          * If write would fit in the cache, and is larger than
680                          * the data already in the cache, flush the cache and
681                          * preferentially copy the data new data into it. Otherwise
682                          * just write the data directly.
683                          */
684
685                         if ( n <= wcp->alloc_size && n > wcp->data_size) {
686                                 cache_flush_needed = True;
687                         } else {
688                                 ssize_t ret = real_write_file(NULL,fsp, data, pos, n);
689
690                                 /*
691                                  * If the write overlaps the entire cache, then
692                                  * discard the current contents of the cache.
693                                  * Fix from Rasmus Borup Hansen rbh@math.ku.dk.
694                                  */
695
696                                 if ((pos <= wcp->offset) &&
697                                                 (pos + n >= wcp->offset + wcp->data_size) ) {
698                                         DEBUG(9,("write_file: discarding overwritten write \
699 cache: fd = %d, off=%.0f, size=%u\n", fsp->fh->fd, (double)wcp->offset, (unsigned int)wcp->data_size ));
700                                         wcp->data_size = 0;
701                                 }
702
703                                 DO_PROFILE_INC(writecache_direct_writes);
704                                 if (ret == -1) {
705                                         return ret;
706                                 }
707
708                                 if (pos + ret > wcp->file_size) {
709                                         wcp->file_size = pos + ret;
710                                 }
711
712                                 return ret;
713                         }
714
715                         write_path = 4;
716
717                 }
718
719                 if (cache_flush_needed) {
720                         DEBUG(3,("WRITE_FLUSH:%d: due to noncontinuous write: fd = %d, size = %.0f, pos = %.0f, \
721 n = %u, wcp->offset=%.0f, wcp->data_size=%u\n",
722                                 write_path, fsp->fh->fd, (double)wcp->file_size, (double)pos, (unsigned int)n,
723                                 (double)wcp->offset, (unsigned int)wcp->data_size ));
724
725                         flush_write_cache(fsp, WRITE_FLUSH);
726                 }
727         }
728
729         /*
730          * If the write request is bigger than the cache
731          * size, write it all out.
732          */
733
734         if (n > wcp->alloc_size ) {
735                 ssize_t ret = real_write_file(NULL,fsp, data, pos, n);
736                 if (ret == -1) {
737                         return -1;
738                 }
739
740                 if (pos + ret > wcp->file_size) {
741                         wcp->file_size = pos + n;
742                 }
743
744                 DO_PROFILE_INC(writecache_direct_writes);
745                 return total_written + n;
746         }
747
748         /*
749          * If there's any data left, cache it.
750          */
751
752         if (n) {
753 #ifdef WITH_PROFILE
754                 if (wcp->data_size) {
755                         DO_PROFILE_INC(writecache_abutted_writes);
756                 } else {
757                         DO_PROFILE_INC(writecache_init_writes);
758                 }
759 #endif
760                 memcpy(wcp->data+wcp->data_size, data, n);
761                 if (wcp->data_size == 0) {
762                         wcp->offset = pos;
763                         DO_PROFILE_INC(writecache_num_write_caches);
764                 }
765                 wcp->data_size += n;
766
767                 /*
768                  * Update the file size if changed.
769                  */
770
771                 if (wcp->offset + wcp->data_size > wcp->file_size) {
772                         if (wcp_file_size_change(fsp) == -1) {
773                                 return -1;
774                         }
775                 }
776                 DEBUG(9,("wcp->offset = %.0f wcp->data_size = %u cache return %u\n",
777                         (double)wcp->offset, (unsigned int)wcp->data_size, (unsigned int)n));
778
779                 total_written += n;
780                 return total_written; /* .... that's a write :) */
781         }
782   
783         return total_written;
784 }
785
786 /****************************************************************************
787  Delete the write cache structure.
788 ****************************************************************************/
789
790 void delete_write_cache(files_struct *fsp)
791 {
792         write_cache *wcp;
793
794         if(!fsp) {
795                 return;
796         }
797
798         if(!(wcp = fsp->wcp)) {
799                 return;
800         }
801
802         DO_PROFILE_DEC(writecache_allocated_write_caches);
803         allocated_write_caches--;
804
805         SMB_ASSERT(wcp->data_size == 0);
806
807         SAFE_FREE(wcp->data);
808         SAFE_FREE(fsp->wcp);
809
810         DEBUG(10,("delete_write_cache: File %s deleted write cache\n", fsp->fsp_name ));
811 }
812
813 /****************************************************************************
814  Setup the write cache structure.
815 ****************************************************************************/
816
817 static bool setup_write_cache(files_struct *fsp, SMB_OFF_T file_size)
818 {
819         ssize_t alloc_size = lp_write_cache_size(SNUM(fsp->conn));
820         write_cache *wcp;
821
822         if (allocated_write_caches >= MAX_WRITE_CACHES) {
823                 return False;
824         }
825
826         if(alloc_size == 0 || fsp->wcp) {
827                 return False;
828         }
829
830         if((wcp = SMB_MALLOC_P(write_cache)) == NULL) {
831                 DEBUG(0,("setup_write_cache: malloc fail.\n"));
832                 return False;
833         }
834
835         wcp->file_size = file_size;
836         wcp->offset = 0;
837         wcp->alloc_size = alloc_size;
838         wcp->data_size = 0;
839         if((wcp->data = (char *)SMB_MALLOC(wcp->alloc_size)) == NULL) {
840                 DEBUG(0,("setup_write_cache: malloc fail for buffer size %u.\n",
841                         (unsigned int)wcp->alloc_size ));
842                 SAFE_FREE(wcp);
843                 return False;
844         }
845
846         memset(wcp->data, '\0', wcp->alloc_size );
847
848         fsp->wcp = wcp;
849         DO_PROFILE_INC(writecache_allocated_write_caches);
850         allocated_write_caches++;
851
852         DEBUG(10,("setup_write_cache: File %s allocated write cache size %lu\n",
853                 fsp->fsp_name, (unsigned long)wcp->alloc_size ));
854
855         return True;
856 }
857
858 /****************************************************************************
859  Cope with a size change.
860 ****************************************************************************/
861
862 void set_filelen_write_cache(files_struct *fsp, SMB_OFF_T file_size)
863 {
864         if(fsp->wcp) {
865                 /* The cache *must* have been flushed before we do this. */
866                 if (fsp->wcp->data_size != 0) {
867                         char *msg;
868                         if (asprintf(&msg, "set_filelen_write_cache: size change "
869                                  "on file %s with write cache size = %lu\n",
870                                  fsp->fsp_name,
871                                  (unsigned long)fsp->wcp->data_size) != -1) {
872                                 smb_panic(msg);
873                         } else {
874                                 smb_panic("set_filelen_write_cache");
875                         }
876                 }
877                 fsp->wcp->file_size = file_size;
878         }
879 }
880
881 /*******************************************************************
882  Flush a write cache struct to disk.
883 ********************************************************************/
884
885 ssize_t flush_write_cache(files_struct *fsp, enum flush_reason_enum reason)
886 {
887         write_cache *wcp = fsp->wcp;
888         size_t data_size;
889         ssize_t ret;
890
891         if(!wcp || !wcp->data_size) {
892                 return 0;
893         }
894
895         data_size = wcp->data_size;
896         wcp->data_size = 0;
897
898         DO_PROFILE_DEC_INC(writecache_num_write_caches,writecache_flushed_writes[reason]);
899
900         DEBUG(9,("flushing write cache: fd = %d, off=%.0f, size=%u\n",
901                 fsp->fh->fd, (double)wcp->offset, (unsigned int)data_size));
902
903 #ifdef WITH_PROFILE
904         if(data_size == wcp->alloc_size) {
905                 DO_PROFILE_INC(writecache_num_perfect_writes);
906         }
907 #endif
908
909         ret = real_write_file(NULL, fsp, wcp->data, wcp->offset, data_size);
910
911         /*
912          * Ensure file size if kept up to date if write extends file.
913          */
914
915         if ((ret != -1) && (wcp->offset + ret > wcp->file_size)) {
916                 wcp->file_size = wcp->offset + ret;
917         }
918
919         return ret;
920 }
921
922 /*******************************************************************
923 sync a file
924 ********************************************************************/
925
926 NTSTATUS sync_file(connection_struct *conn, files_struct *fsp, bool write_through)
927 {
928         if (fsp->fh->fd == -1)
929                 return NT_STATUS_INVALID_HANDLE;
930
931         if (lp_strict_sync(SNUM(conn)) &&
932             (lp_syncalways(SNUM(conn)) || write_through)) {
933                 int ret = flush_write_cache(fsp, SYNC_FLUSH);
934                 if (ret == -1) {
935                         return map_nt_error_from_unix(errno);
936                 }
937                 ret = SMB_VFS_FSYNC(fsp);
938                 if (ret == -1) {
939                         return map_nt_error_from_unix(errno);
940                 }
941         }
942         return NT_STATUS_OK;
943 }
944
945 /************************************************************
946  Perform a stat whether a valid fd or not.
947 ************************************************************/
948
949 int fsp_stat(files_struct *fsp, SMB_STRUCT_STAT *pst)
950 {
951         if (fsp->fh->fd == -1) {
952                 return vfs_stat_smb_fname(fsp->conn, fsp->fsp_name, pst);
953         } else {
954                 return SMB_VFS_FSTAT(fsp, pst);
955         }
956 }