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 "printing.h"
  24 #include "smbd/globals.h"
  25
  26 static bool setup_write_cache(files_struct *, SMB_OFF_T);
  27
  28 /****************************************************************************
  29  Read from write cache if we can.
  30 ****************************************************************************/
  31
  32 static bool read_from_write_cache(files_struct *fsp,char *data,SMB_OFF_T pos,size_t n)
  33 {
  34         write_cache *wcp = fsp->wcp;
  35
  36         if(!wcp) {
  37                 return False;
  38         }
  39
  40         if( n > wcp->data_size || pos < wcp->offset || pos + n > wcp->offset + wcp->data_size) {
  41                 return False;
  42         }
  43
  44         memcpy(data, wcp->data + (pos - wcp->offset), n);
  45
  46         DO_PROFILE_INC(writecache_read_hits);
  47
  48         return True;
  49 }
  50
  51 /****************************************************************************
  52  Read from a file.
  53 ****************************************************************************/
  54
  55 ssize_t read_file(files_struct *fsp,char *data,SMB_OFF_T pos,size_t n)
  56 {
  57         ssize_t ret=0,readret;
  58
  59         /* you can't read from print files */
  60         if (fsp->print_file) {
  61                 errno = EBADF;
  62                 return -1;
  63         }
  64
  65         /*
  66          * Serve from write cache if we can.
  67          */
  68
  69         if(read_from_write_cache(fsp, data, pos, n)) {
  70                 fsp->fh->pos = pos + n;
  71                 fsp->fh->position_information = fsp->fh->pos;
  72                 return n;
  73         }
  74
  75         flush_write_cache(fsp, READ_FLUSH);
  76
  77         fsp->fh->pos = pos;
  78
  79         if (n > 0) {
  80 #ifdef DMF_FIX
  81                 int numretries = 3;
  82 tryagain:
  83                 readret = SMB_VFS_PREAD(fsp,data,n,pos);
  84
  85                 if (readret == -1) {
  86                         if ((errno == EAGAIN) && numretries) {
  87                                 DEBUG(3,("read_file EAGAIN retry in 10 seconds\n"));
  88                                 (void)sleep(10);
  89                                 --numretries;
  90                                 goto tryagain;
  91                         }
  92                         return -1;
  93                 }
  94 #else /* NO DMF fix. */
  95                 readret = SMB_VFS_PREAD(fsp,data,n,pos);
  96
  97                 if (readret == -1) {
  98                         return -1;
  99                 }
 100 #endif
 101                 if (readret > 0) {
 102                         ret += readret;
 103                 }
 104         }
 105
 106         DEBUG(10,("read_file (%s): pos = %.0f, size = %lu, returned %lu\n",
 107                   fsp_str_dbg(fsp), (double)pos, (unsigned long)n, (long)ret));
 108
 109         fsp->fh->pos += ret;
 110         fsp->fh->position_information = fsp->fh->pos;
 111
 112         return(ret);
 113 }
 114
 115 /****************************************************************************
 116  *Really* write to a file.
 117 ****************************************************************************/
 118
 119 static ssize_t real_write_file(struct smb_request *req,
 120                                 files_struct *fsp,
 121                                 const char *data,
 122                                 SMB_OFF_T pos,
 123                                 size_t n)
 124 {
 125         ssize_t ret;
 126
 127         if (pos == -1) {
 128                 ret = vfs_write_data(req, fsp, data, n);
 129         } else {
 130                 fsp->fh->pos = pos;
 131                 if (pos && lp_strict_allocate(SNUM(fsp->conn))) {
 132                         if (vfs_fill_sparse(fsp, pos) == -1) {
 133                                 return -1;
 134                         }
 135                 }
 136                 ret = vfs_pwrite_data(req, fsp, data, n, pos);
 137         }
 138
 139         DEBUG(10,("real_write_file (%s): pos = %.0f, size = %lu, returned %ld\n",
 140                   fsp_str_dbg(fsp), (double)pos, (unsigned long)n, (long)ret));
 141
 142         if (ret != -1) {
 143                 fsp->fh->pos += ret;
 144
 145 /* Yes - this is correct - writes don't update this. JRA. */
 146 /* Found by Samba4 tests. */
 147 #if 0
 148                 fsp->position_information = fsp->pos;
 149 #endif
 150         }
 151
 152         return ret;
 153 }
 154
 155 /****************************************************************************
 156  File size cache change.
 157  Updates size on disk but doesn't flush the cache.
 158 ****************************************************************************/
 159
 160 static int wcp_file_size_change(files_struct *fsp)
 161 {
 162         int ret;
 163         write_cache *wcp = fsp->wcp;
 164
 165         wcp->file_size = wcp->offset + wcp->data_size;
 166         ret = SMB_VFS_FTRUNCATE(fsp, wcp->file_size);
 167         if (ret == -1) {
 168                 DEBUG(0,("wcp_file_size_change (%s): ftruncate of size %.0f "
 169                          "error %s\n", fsp_str_dbg(fsp),
 170                          (double)wcp->file_size, strerror(errno)));
 171         }
 172         return ret;
 173 }
 174
 175 void update_write_time_handler(struct event_context *ctx,
 176                                       struct timed_event *te,
 177                                       struct timeval now,
 178                                       void *private_data)
 179 {
 180         files_struct *fsp = (files_struct *)private_data;
 181
 182         DEBUG(5, ("Update write time on %s\n", fsp_str_dbg(fsp)));
 183
 184         /* change the write time in the open file db. */
 185         (void)set_write_time(fsp->file_id, timespec_current());
 186
 187         /* And notify. */
 188         notify_fname(fsp->conn, NOTIFY_ACTION_MODIFIED,
 189                      FILE_NOTIFY_CHANGE_LAST_WRITE, fsp->fsp_name->base_name);
 190
 191         /* Remove the timed event handler. */
 192         TALLOC_FREE(fsp->update_write_time_event);
 193 }
 194
 195 /*********************************************************
 196  Schedule a write time update for WRITE_TIME_UPDATE_USEC_DELAY
 197  in the future.
 198 *********************************************************/
 199
 200 void trigger_write_time_update(struct files_struct *fsp)
 201 {
 202         int delay;
 203
 204         if (fsp->posix_open) {
 205                 /* Don't use delayed writes on POSIX files. */
 206                 return;
 207         }
 208
 209         if (fsp->write_time_forced) {
 210                 /* No point - "sticky" write times
 211                  * in effect.
 212                  */
 213                 return;
 214         }
 215
 216         /* We need to remember someone did a write
 217          * and update to current time on close. */
 218
 219         fsp->update_write_time_on_close = true;
 220
 221         if (fsp->update_write_time_triggered) {
 222                 /*
 223                  * We only update the write time after 2 seconds
 224                  * on the first normal write. After that
 225                  * no other writes affect this until close.
 226                  */
 227                 return;
 228         }
 229         fsp->update_write_time_triggered = true;
 230
 231         delay = lp_parm_int(SNUM(fsp->conn),
 232                             "smbd", "writetimeupdatedelay",
 233                             WRITE_TIME_UPDATE_USEC_DELAY);
 234
 235         DEBUG(5, ("Update write time %d usec later on %s\n",
 236                   delay, fsp_str_dbg(fsp)));
 237
 238         /* trigger the update 2 seconds later */
 239         fsp->update_write_time_event =
 240                 event_add_timed(smbd_event_context(), NULL,
 241                                 timeval_current_ofs(0, delay),
 242                                 update_write_time_handler, fsp);
 243 }
 244
 245 void trigger_write_time_update_immediate(struct files_struct *fsp)
 246 {
 247         struct smb_file_time ft;
 248
 249         if (fsp->posix_open) {
 250                 /* Don't use delayed writes on POSIX files. */
 251                 return;
 252         }
 253
 254         if (fsp->write_time_forced) {
 255                 /*
 256                  * No point - "sticky" write times
 257                  * in effect.
 258                  */
 259                 return;
 260         }
 261
 262         TALLOC_FREE(fsp->update_write_time_event);
 263         DEBUG(5, ("Update write time immediate on %s\n",
 264                   fsp_str_dbg(fsp)));
 265
 266         /* After an immediate update, reset the trigger. */
 267         fsp->update_write_time_triggered = true;
 268         fsp->update_write_time_on_close = false;
 269
 270         ZERO_STRUCT(ft);
 271         ft.mtime = timespec_current();
 272
 273         /* Update the time in the open file db. */
 274         (void)set_write_time(fsp->file_id, ft.mtime);
 275
 276         /* Now set on disk - takes care of notify. */
 277         (void)smb_set_file_time(fsp->conn, fsp, fsp->fsp_name, &ft, false);
 278 }
 279
 280 /****************************************************************************
 281  Write to a file.
 282 ****************************************************************************/
 283
 284 ssize_t write_file(struct smb_request *req,
 285                         files_struct *fsp,
 286                         const char *data,
 287                         SMB_OFF_T pos,
 288                         size_t n)
 289 {
 290         write_cache *wcp = fsp->wcp;
 291         ssize_t total_written = 0;
 292         int write_path = -1;
 293
 294         if (fsp->print_file) {
 295                 uint32_t t;
 296                 int ret;
 297
 298                 ret = print_spool_write(fsp, data, n, pos, &t);
 299                 if (ret) {
 300                         errno = ret;
 301                         return -1;
 302                 }
 303                 return t;
 304         }
 305
 306         if (!fsp->can_write) {
 307                 errno = EPERM;
 308                 return -1;
 309         }
 310
 311         if (!fsp->modified) {
 312                 fsp->modified = True;
 313
 314                 if (SMB_VFS_FSTAT(fsp, &fsp->fsp_name->st) == 0) {
 315                         int dosmode;
 316                         trigger_write_time_update(fsp);
 317                         dosmode = dos_mode(fsp->conn, fsp->fsp_name);
 318                         if ((lp_store_dos_attributes(SNUM(fsp->conn)) ||
 319                                         MAP_ARCHIVE(fsp->conn)) &&
 320                                         !IS_DOS_ARCHIVE(dosmode)) {
 321                                 file_set_dosmode(fsp->conn, fsp->fsp_name,
 322                                                  dosmode | aARCH, NULL, false);
 323                         }
 324
 325                         /*
 326                          * If this is the first write and we have an exclusive oplock then setup
 327                          * the write cache.
 328                          */
 329
 330                         if (EXCLUSIVE_OPLOCK_TYPE(fsp->oplock_type) && !wcp) {
 331                                 setup_write_cache(fsp,
 332                                                  fsp->fsp_name->st.st_ex_size);
 333                                 wcp = fsp->wcp;
 334                         }
 335                 }
 336         }
 337
 338 #ifdef WITH_PROFILE
 339         DO_PROFILE_INC(writecache_total_writes);
 340         if (!fsp->oplock_type) {
 341                 DO_PROFILE_INC(writecache_non_oplock_writes);
 342         }
 343 #endif
 344
 345         /*
 346          * If this file is level II oplocked then we need
 347          * to grab the shared memory lock and inform all
 348          * other files with a level II lock that they need
 349          * to flush their read caches. We keep the lock over
 350          * the shared memory area whilst doing this.
 351          */
 352
 353         /* This should actually be improved to span the write. */
 354         contend_level2_oplocks_begin(fsp, LEVEL2_CONTEND_WRITE);
 355         contend_level2_oplocks_end(fsp, LEVEL2_CONTEND_WRITE);
 356
 357 #ifdef WITH_PROFILE
 358         if (profile_p && profile_p->writecache_total_writes % 500 == 0) {
 359                 DEBUG(3,("WRITECACHE: initwrites=%u abutted=%u total=%u \
 360 nonop=%u allocated=%u active=%u direct=%u perfect=%u readhits=%u\n",
 361                         profile_p->writecache_init_writes,
 362                         profile_p->writecache_abutted_writes,
 363                         profile_p->writecache_total_writes,
 364                         profile_p->writecache_non_oplock_writes,
 365                         profile_p->writecache_allocated_write_caches,
 366                         profile_p->writecache_num_write_caches,
 367                         profile_p->writecache_direct_writes,
 368                         profile_p->writecache_num_perfect_writes,
 369                         profile_p->writecache_read_hits ));
 370
 371                 DEBUG(3,("WRITECACHE: Flushes SEEK=%d, READ=%d, WRITE=%d, READRAW=%d, OPLOCK=%d, CLOSE=%d, SYNC=%d\n",
 372                         profile_p->writecache_flushed_writes[SEEK_FLUSH],
 373                         profile_p->writecache_flushed_writes[READ_FLUSH],
 374                         profile_p->writecache_flushed_writes[WRITE_FLUSH],
 375                         profile_p->writecache_flushed_writes[READRAW_FLUSH],
 376                         profile_p->writecache_flushed_writes[OPLOCK_RELEASE_FLUSH],
 377                         profile_p->writecache_flushed_writes[CLOSE_FLUSH],
 378                         profile_p->writecache_flushed_writes[SYNC_FLUSH] ));
 379         }
 380 #endif
 381
 382         if (wcp && req->unread_bytes) {
 383                 /* If we're using receivefile don't
 384                  * deal with a write cache.
 385                  */
 386                 flush_write_cache(fsp, WRITE_FLUSH);
 387                 delete_write_cache(fsp);
 388                 wcp = NULL;
 389         }
 390
 391         if(!wcp) {
 392                 DO_PROFILE_INC(writecache_direct_writes);
 393                 total_written = real_write_file(req, fsp, data, pos, n);
 394                 return total_written;
 395         }
 396
 397         DEBUG(9,("write_file (%s)(fd=%d pos=%.0f size=%u) wcp->offset=%.0f "
 398                  "wcp->data_size=%u\n", fsp_str_dbg(fsp), fsp->fh->fd,
 399                  (double)pos, (unsigned int)n, (double)wcp->offset,
 400                  (unsigned int)wcp->data_size));
 401
 402         fsp->fh->pos = pos + n;
 403
 404         /*
 405          * If we have active cache and it isn't contiguous then we flush.
 406          * NOTE: There is a small problem with running out of disk ....
 407          */
 408
 409         if (wcp->data_size) {
 410                 bool cache_flush_needed = False;
 411
 412                 if ((pos >= wcp->offset) && (pos <= wcp->offset + wcp->data_size)) {
 413
 414                         /* ASCII art.... JRA.
 415
 416       +--------------+-----
 417       | Cached data  | Rest of allocated cache buffer....
 418       +--------------+-----
 419
 420             +-------------------+
 421             | Data to write     |
 422             +-------------------+
 423
 424                         */
 425
 426                         /*
 427                          * Start of write overlaps or abutts the existing data.
 428                          */
 429
 430                         size_t data_used = MIN((wcp->alloc_size - (pos - wcp->offset)), n);
 431
 432                         memcpy(wcp->data + (pos - wcp->offset), data, data_used);
 433
 434                         /*
 435                          * Update the current buffer size with the new data.
 436                          */
 437
 438                         if(pos + data_used > wcp->offset + wcp->data_size) {
 439                                 wcp->data_size = pos + data_used - wcp->offset;
 440                         }
 441
 442                         /*
 443                          * Update the file size if changed.
 444                          */
 445
 446                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 447                                 if (wcp_file_size_change(fsp) == -1) {
 448                                         return -1;
 449                                 }
 450                         }
 451
 452                         /*
 453                          * If we used all the data then
 454                          * return here.
 455                          */
 456
 457                         if(n == data_used) {
 458                                 return n;
 459                         } else {
 460                                 cache_flush_needed = True;
 461                         }
 462                         /*
 463                          * Move the start of data forward by the amount used,
 464                          * cut down the amount left by the same amount.
 465                          */
 466
 467                         data += data_used;
 468                         pos += data_used;
 469                         n -= data_used;
 470
 471                         DO_PROFILE_INC(writecache_abutted_writes);
 472                         total_written = data_used;
 473
 474                         write_path = 1;
 475
 476                 } else if ((pos < wcp->offset) && (pos + n > wcp->offset) &&
 477                                         (pos + n <= wcp->offset + wcp->alloc_size)) {
 478
 479                         /* ASCII art.... JRA.
 480
 481                         +---------------+
 482                         | Cache buffer  |
 483                         +---------------+
 484
 485             +-------------------+
 486             | Data to write     |
 487             +-------------------+
 488
 489                         */
 490
 491                         /*
 492                          * End of write overlaps the existing data.
 493                          */
 494
 495                         size_t data_used = pos + n - wcp->offset;
 496
 497                         memcpy(wcp->data, data + n - data_used, data_used);
 498
 499                         /*
 500                          * Update the current buffer size with the new data.
 501                          */
 502
 503                         if(pos + n > wcp->offset + wcp->data_size) {
 504                                 wcp->data_size = pos + n - wcp->offset;
 505                         }
 506
 507                         /*
 508                          * Update the file size if changed.
 509                          */
 510
 511                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 512                                 if (wcp_file_size_change(fsp) == -1) {
 513                                         return -1;
 514                                 }
 515                         }
 516
 517                         /*
 518                          * We don't need to move the start of data, but we
 519                          * cut down the amount left by the amount used.
 520                          */
 521
 522                         n -= data_used;
 523
 524                         /*
 525                          * We cannot have used all the data here.
 526                          */
 527
 528                         cache_flush_needed = True;
 529
 530                         DO_PROFILE_INC(writecache_abutted_writes);
 531                         total_written = data_used;
 532
 533                         write_path = 2;
 534
 535                 } else if ( (pos >= wcp->file_size) &&
 536                                         (wcp->offset + wcp->data_size == wcp->file_size) &&
 537                                         (pos > wcp->offset + wcp->data_size) &&
 538                                         (pos < wcp->offset + wcp->alloc_size) ) {
 539
 540                         /* ASCII art.... JRA.
 541
 542                        End of file ---->|
 543
 544                         +---------------+---------------+
 545                         | Cached data   | Cache buffer  |
 546                         +---------------+---------------+
 547
 548                                               +-------------------+
 549                                               | Data to write     |
 550                                               +-------------------+
 551
 552                         */
 553
 554                         /*
 555                          * Non-contiguous write part of which fits within
 556                          * the cache buffer and is extending the file
 557                          * and the cache contents reflect the current
 558                          * data up to the current end of the file.
 559                          */
 560
 561                         size_t data_used;
 562
 563                         if(pos + n <= wcp->offset + wcp->alloc_size) {
 564                                 data_used = n;
 565                         } else {
 566                                 data_used = wcp->offset + wcp->alloc_size - pos;
 567                         }
 568
 569                         /*
 570                          * Fill in the non-continuous area with zeros.
 571                          */
 572
 573                         memset(wcp->data + wcp->data_size, '\0',
 574                                 pos - (wcp->offset + wcp->data_size) );
 575
 576                         memcpy(wcp->data + (pos - wcp->offset), data, data_used);
 577
 578                         /*
 579                          * Update the current buffer size with the new data.
 580                          */
 581
 582                         if(pos + data_used > wcp->offset + wcp->data_size) {
 583                                 wcp->data_size = pos + data_used - wcp->offset;
 584                         }
 585
 586                         /*
 587                          * Update the file size if changed.
 588                          */
 589
 590                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 591                                 if (wcp_file_size_change(fsp) == -1) {
 592                                         return -1;
 593                                 }
 594                         }
 595
 596                         /*
 597                          * If we used all the data then
 598                          * return here.
 599                          */
 600
 601                         if(n == data_used) {
 602                                 return n;
 603                         } else {
 604                                 cache_flush_needed = True;
 605                         }
 606
 607                         /*
 608                          * Move the start of data forward by the amount used,
 609                          * cut down the amount left by the same amount.
 610                          */
 611
 612                         data += data_used;
 613                         pos += data_used;
 614                         n -= data_used;
 615
 616                         DO_PROFILE_INC(writecache_abutted_writes);
 617                         total_written = data_used;
 618
 619                         write_path = 3;
 620
 621                 } else if ( (pos >= wcp->file_size) &&
 622                             (n == 1) &&
 623                             (wcp->file_size == wcp->offset + wcp->data_size) &&
 624                             (pos < wcp->file_size + wcp->alloc_size)) {
 625
 626                         /*
 627
 628                 End of file ---->|
 629
 630                  +---------------+---------------+
 631                  | Cached data   | Cache buffer  |
 632                  +---------------+---------------+
 633
 634                                  |<------- allocated size ---------------->|
 635
 636                                                          +--------+
 637                                                          | 1 Byte |
 638                                                          +--------+
 639
 640                         MS-Office seems to do this a lot to determine if there's enough
 641                         space on the filesystem to write a new file.
 642
 643                         Change to :
 644
 645                 End of file ---->|
 646                                  +-----------------------+--------+
 647                                  | Zeroed Cached data    | 1 Byte |
 648                                  +-----------------------+--------+
 649                         */
 650
 651                         flush_write_cache(fsp, WRITE_FLUSH);
 652
 653                         if (data[0] == '\0') {
 654                                 /*
 655                                  * This is a 1-byte write of a 0
 656                                  * beyond the EOF, the typical
 657                                  * file-extending (and allocating, but
 658                                  * we're using the write cache here)
 659                                  * write done by Windows. We just have
 660                                  * to ftruncate the file and rely on
 661                                  * posix semantics to return zeros for
 662                                  * non-written file data that is
 663                                  * within the file length.
 664                                  *
 665                                  * We have to cheat the offset to make
 666                                  * wcp_file_size_change do the right
 667                                  * thing with the ftruncate call.
 668                                  */
 669                                 wcp->offset = pos + 1;
 670                                 wcp->data_size = 0;
 671                         } else {
 672                                 wcp->offset = wcp->file_size;
 673                                 wcp->data_size = pos - wcp->file_size + 1;
 674                                 memset(wcp->data, '\0', wcp->data_size);
 675                                 memcpy(wcp->data + wcp->data_size-1, data, 1);
 676                         }
 677
 678                         /*
 679                          * Update the file size if changed.
 680                          */
 681
 682                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 683                                 if (wcp_file_size_change(fsp) == -1) {
 684                                         return -1;
 685                                 }
 686                         }
 687
 688                         return n;
 689
 690                 } else {
 691
 692                         /* ASCII art..... JRA.
 693
 694    Case 1).
 695
 696                         +---------------+---------------+
 697                         | Cached data   | Cache buffer  |
 698                         +---------------+---------------+
 699
 700                                                               +-------------------+
 701                                                               | Data to write     |
 702                                                               +-------------------+
 703
 704    Case 2).
 705
 706                            +---------------+---------------+
 707                            | Cached data   | Cache buffer  |
 708                            +---------------+---------------+
 709
 710    +-------------------+
 711    | Data to write     |
 712    +-------------------+
 713
 714     Case 3).
 715
 716                            +---------------+---------------+
 717                            | Cached data   | Cache buffer  |
 718                            +---------------+---------------+
 719
 720                   +-----------------------------------------------------+
 721                   | Data to write                                       |
 722                   +-----------------------------------------------------+
 723
 724                   */
 725
 726                         /*
 727                          * Write is bigger than buffer, or there is no overlap on the
 728                          * low or high ends.
 729                          */
 730
 731                         DEBUG(9,("write_file: non cacheable write : fd = %d, pos = %.0f, len = %u, current cache pos = %.0f \
 732 len = %u\n",fsp->fh->fd, (double)pos, (unsigned int)n, (double)wcp->offset, (unsigned int)wcp->data_size ));
 733
 734                         /*
 735                          * If write would fit in the cache, and is larger than
 736                          * the data already in the cache, flush the cache and
 737                          * preferentially copy the data new data into it. Otherwise
 738                          * just write the data directly.
 739                          */
 740
 741                         if ( n <= wcp->alloc_size && n > wcp->data_size) {
 742                                 cache_flush_needed = True;
 743                         } else {
 744                                 ssize_t ret = real_write_file(NULL,fsp, data, pos, n);
 745
 746                                 /*
 747                                  * If the write overlaps the entire cache, then
 748                                  * discard the current contents of the cache.
 749                                  * Fix from Rasmus Borup Hansen rbh@math.ku.dk.
 750                                  */
 751
 752                                 if ((pos <= wcp->offset) &&
 753                                                 (pos + n >= wcp->offset + wcp->data_size) ) {
 754                                         DEBUG(9,("write_file: discarding overwritten write \
 755 cache: fd = %d, off=%.0f, size=%u\n", fsp->fh->fd, (double)wcp->offset, (unsigned int)wcp->data_size ));
 756                                         wcp->data_size = 0;
 757                                 }
 758
 759                                 DO_PROFILE_INC(writecache_direct_writes);
 760                                 if (ret == -1) {
 761                                         return ret;
 762                                 }
 763
 764                                 if (pos + ret > wcp->file_size) {
 765                                         wcp->file_size = pos + ret;
 766                                 }
 767
 768                                 return ret;
 769                         }
 770
 771                         write_path = 4;
 772
 773                 }
 774
 775                 if (cache_flush_needed) {
 776                         DEBUG(3,("WRITE_FLUSH:%d: due to noncontinuous write: fd = %d, size = %.0f, pos = %.0f, \
 777 n = %u, wcp->offset=%.0f, wcp->data_size=%u\n",
 778                                 write_path, fsp->fh->fd, (double)wcp->file_size, (double)pos, (unsigned int)n,
 779                                 (double)wcp->offset, (unsigned int)wcp->data_size ));
 780
 781                         flush_write_cache(fsp, WRITE_FLUSH);
 782                 }
 783         }
 784
 785         /*
 786          * If the write request is bigger than the cache
 787          * size, write it all out.
 788          */
 789
 790         if (n > wcp->alloc_size ) {
 791                 ssize_t ret = real_write_file(NULL,fsp, data, pos, n);
 792                 if (ret == -1) {
 793                         return -1;
 794                 }
 795
 796                 if (pos + ret > wcp->file_size) {
 797                         wcp->file_size = pos + n;
 798                 }
 799
 800                 DO_PROFILE_INC(writecache_direct_writes);
 801                 return total_written + n;
 802         }
 803
 804         /*
 805          * If there's any data left, cache it.
 806          */
 807
 808         if (n) {
 809 #ifdef WITH_PROFILE
 810                 if (wcp->data_size) {
 811                         DO_PROFILE_INC(writecache_abutted_writes);
 812                 } else {
 813                         DO_PROFILE_INC(writecache_init_writes);
 814                 }
 815 #endif
 816
 817                 if ((wcp->data_size == 0)
 818                     && (pos > wcp->file_size)
 819                     && (n == 1)
 820                     && (data[0] == '\0')) {
 821                         /*
 822                          * This is a 1-byte write of a 0 beyond the
 823                          * EOF, the typical file-extending (and
 824                          * allocating, but we're using the write cache
 825                          * here) write done by Windows. We just have
 826                          * to ftruncate the file and rely on posix
 827                          * semantics to return zeros for non-written
 828                          * file data that is within the file length.
 829                          *
 830                          * We have to cheat the offset to make
 831                          * wcp_file_size_change do the right thing
 832                          * with the ftruncate call.
 833                          */
 834                         wcp->offset = pos+1;
 835                         wcp->data_size = 0;
 836                         if (wcp_file_size_change(fsp) == -1) {
 837                                 return -1;
 838                         }
 839                         return 1;
 840                 }
 841
 842                 if ((wcp->data_size == 0)
 843                     && (pos > wcp->file_size)
 844                     && (pos + n <= wcp->file_size + wcp->alloc_size)) {
 845                         /*
 846                          * This is a write completely beyond the
 847                          * current EOF, but within reach of the write
 848                          * cache. We expect fill-up writes pretty
 849                          * soon, so it does not make sense to start
 850                          * the write cache at the current
 851                          * offset. These fill-up writes would trigger
 852                          * separate pwrites or even unnecessary cache
 853                          * flushes because they overlap if this is a
 854                          * one-byte allocating write.
 855                          */
 856                         wcp->offset = wcp->file_size;
 857                         wcp->data_size = pos - wcp->file_size;
 858                         memset(wcp->data, 0, wcp->data_size);
 859                 }
 860
 861                 memcpy(wcp->data+wcp->data_size, data, n);
 862                 if (wcp->data_size == 0) {
 863                         wcp->offset = pos;
 864                         DO_PROFILE_INC(writecache_num_write_caches);
 865                 }
 866                 wcp->data_size += n;
 867
 868                 /*
 869                  * Update the file size if changed.
 870                  */
 871
 872                 if (wcp->offset + wcp->data_size > wcp->file_size) {
 873                         if (wcp_file_size_change(fsp) == -1) {
 874                                 return -1;
 875                         }
 876                 }
 877                 DEBUG(9,("wcp->offset = %.0f wcp->data_size = %u cache return %u\n",
 878                         (double)wcp->offset, (unsigned int)wcp->data_size, (unsigned int)n));
 879
 880                 total_written += n;
 881                 return total_written; /* .... that's a write :) */
 882         }
 883
 884         return total_written;
 885 }
 886
 887 /****************************************************************************
 888  Delete the write cache structure.
 889 ****************************************************************************/
 890
 891 void delete_write_cache(files_struct *fsp)
 892 {
 893         write_cache *wcp;
 894
 895         if(!fsp) {
 896                 return;
 897         }
 898
 899         if(!(wcp = fsp->wcp)) {
 900                 return;
 901         }
 902
 903         DO_PROFILE_DEC(writecache_allocated_write_caches);
 904         allocated_write_caches--;
 905
 906         SMB_ASSERT(wcp->data_size == 0);
 907
 908         SAFE_FREE(wcp->data);
 909         SAFE_FREE(fsp->wcp);
 910
 911         DEBUG(10,("delete_write_cache: File %s deleted write cache\n",
 912                   fsp_str_dbg(fsp)));
 913 }
 914
 915 /****************************************************************************
 916  Setup the write cache structure.
 917 ****************************************************************************/
 918
 919 static bool setup_write_cache(files_struct *fsp, SMB_OFF_T file_size)
 920 {
 921         ssize_t alloc_size = lp_write_cache_size(SNUM(fsp->conn));
 922         write_cache *wcp;
 923
 924         if (allocated_write_caches >= MAX_WRITE_CACHES) {
 925                 return False;
 926         }
 927
 928         if(alloc_size == 0 || fsp->wcp) {
 929                 return False;
 930         }
 931
 932         if((wcp = SMB_MALLOC_P(write_cache)) == NULL) {
 933                 DEBUG(0,("setup_write_cache: malloc fail.\n"));
 934                 return False;
 935         }
 936
 937         wcp->file_size = file_size;
 938         wcp->offset = 0;
 939         wcp->alloc_size = alloc_size;
 940         wcp->data_size = 0;
 941         if((wcp->data = (char *)SMB_MALLOC(wcp->alloc_size)) == NULL) {
 942                 DEBUG(0,("setup_write_cache: malloc fail for buffer size %u.\n",
 943                         (unsigned int)wcp->alloc_size ));
 944                 SAFE_FREE(wcp);
 945                 return False;
 946         }
 947
 948         memset(wcp->data, '\0', wcp->alloc_size );
 949
 950         fsp->wcp = wcp;
 951         DO_PROFILE_INC(writecache_allocated_write_caches);
 952         allocated_write_caches++;
 953
 954         DEBUG(10,("setup_write_cache: File %s allocated write cache size %lu\n",
 955                   fsp_str_dbg(fsp), (unsigned long)wcp->alloc_size));
 956
 957         return True;
 958 }
 959
 960 /****************************************************************************
 961  Cope with a size change.
 962 ****************************************************************************/
 963
 964 void set_filelen_write_cache(files_struct *fsp, SMB_OFF_T file_size)
 965 {
 966         if(fsp->wcp) {
 967                 /* The cache *must* have been flushed before we do this. */
 968                 if (fsp->wcp->data_size != 0) {
 969                         char *msg;
 970                         if (asprintf(&msg, "set_filelen_write_cache: size change "
 971                                  "on file %s with write cache size = %lu\n",
 972                                  fsp->fsp_name->base_name,
 973                                  (unsigned long)fsp->wcp->data_size) != -1) {
 974                                 smb_panic(msg);
 975                         } else {
 976                                 smb_panic("set_filelen_write_cache");
 977                         }
 978                 }
 979                 fsp->wcp->file_size = file_size;
 980         }
 981 }
 982
 983 /*******************************************************************
 984  Flush a write cache struct to disk.
 985 ********************************************************************/
 986
 987 ssize_t flush_write_cache(files_struct *fsp, enum flush_reason_enum reason)
 988 {
 989         write_cache *wcp = fsp->wcp;
 990         size_t data_size;
 991         ssize_t ret;
 992
 993         if(!wcp || !wcp->data_size) {
 994                 return 0;
 995         }
 996
 997         data_size = wcp->data_size;
 998         wcp->data_size = 0;
 999
1000         DO_PROFILE_DEC_INC(writecache_num_write_caches,writecache_flushed_writes[reason]);
1001
1002         DEBUG(9,("flushing write cache: fd = %d, off=%.0f, size=%u\n",
1003                 fsp->fh->fd, (double)wcp->offset, (unsigned int)data_size));
1004
1005 #ifdef WITH_PROFILE
1006         if(data_size == wcp->alloc_size) {
1007                 DO_PROFILE_INC(writecache_num_perfect_writes);
1008         }
1009 #endif
1010
1011         ret = real_write_file(NULL, fsp, wcp->data, wcp->offset, data_size);
1012
1013         /*
1014          * Ensure file size if kept up to date if write extends file.
1015          */
1016
1017         if ((ret != -1) && (wcp->offset + ret > wcp->file_size)) {
1018                 wcp->file_size = wcp->offset + ret;
1019         }
1020
1021         return ret;
1022 }
1023
1024 /*******************************************************************
1025 sync a file
1026 ********************************************************************/
1027
1028 NTSTATUS sync_file(connection_struct *conn, files_struct *fsp, bool write_through)
1029 {
1030         if (fsp->fh->fd == -1)
1031                 return NT_STATUS_INVALID_HANDLE;
1032
1033         if (lp_strict_sync(SNUM(conn)) &&
1034             (lp_syncalways(SNUM(conn)) || write_through)) {
1035                 int ret = flush_write_cache(fsp, SYNC_FLUSH);
1036                 if (ret == -1) {
1037                         return map_nt_error_from_unix(errno);
1038                 }
1039                 ret = SMB_VFS_FSYNC(fsp);
1040                 if (ret == -1) {
1041                         return map_nt_error_from_unix(errno);
1042                 }
1043         }
1044         return NT_STATUS_OK;
1045 }
1046
1047 /************************************************************
1048  Perform a stat whether a valid fd or not.
1049 ************************************************************/
1050
1051 int fsp_stat(files_struct *fsp)
1052 {
1053         if (fsp->fh->fd == -1) {
1054                 if (fsp->posix_open) {
1055                         return SMB_VFS_LSTAT(fsp->conn, fsp->fsp_name);
1056                 } else {
1057                         return SMB_VFS_STAT(fsp->conn, fsp->fsp_name);
1058                 }
1059         } else {
1060                 return SMB_VFS_FSTAT(fsp, &fsp->fsp_name->st);
1061         }
1062 }