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         if ((n == 1) && (data[0] == '\0') && (pos > wcp->file_size)) {
 405                 int ret;
 406
 407                 /*
 408                  * This is a 1-byte write of a 0 beyond the EOF and
 409                  * thus implicitly also beyond the current active
 410                  * write cache, the typical file-extending (and
 411                  * allocating, but we're using the write cache here)
 412                  * write done by Windows. We just have to ftruncate
 413                  * the file and rely on posix semantics to return
 414                  * zeros for non-written file data that is within the
 415                  * file length.
 416                  *
 417                  * We can not use wcp_file_size_change here because we
 418                  * might have an existing write cache, and
 419                  * wcp_file_size_change assumes a change to just the
 420                  * end of the current write cache.
 421                  */
 422
 423                 wcp->file_size = pos + 1;
 424                 ret = SMB_VFS_FTRUNCATE(fsp, wcp->file_size);
 425                 if (ret == -1) {
 426                         DEBUG(0,("wcp_file_size_change (%s): ftruncate of size %.0f"
 427                                  "error %s\n", fsp_str_dbg(fsp),
 428                                  (double)wcp->file_size, strerror(errno)));
 429                         return -1;
 430                 }
 431                 return 1;
 432         }
 433
 434
 435         /*
 436          * If we have active cache and it isn't contiguous then we flush.
 437          * NOTE: There is a small problem with running out of disk ....
 438          */
 439
 440         if (wcp->data_size) {
 441                 bool cache_flush_needed = False;
 442
 443                 if ((pos >= wcp->offset) && (pos <= wcp->offset + wcp->data_size)) {
 444
 445                         /* ASCII art.... JRA.
 446
 447       +--------------+-----
 448       | Cached data  | Rest of allocated cache buffer....
 449       +--------------+-----
 450
 451             +-------------------+
 452             | Data to write     |
 453             +-------------------+
 454
 455                         */
 456
 457                         /*
 458                          * Start of write overlaps or abutts the existing data.
 459                          */
 460
 461                         size_t data_used = MIN((wcp->alloc_size - (pos - wcp->offset)), n);
 462
 463                         memcpy(wcp->data + (pos - wcp->offset), data, data_used);
 464
 465                         /*
 466                          * Update the current buffer size with the new data.
 467                          */
 468
 469                         if(pos + data_used > wcp->offset + wcp->data_size) {
 470                                 wcp->data_size = pos + data_used - wcp->offset;
 471                         }
 472
 473                         /*
 474                          * Update the file size if changed.
 475                          */
 476
 477                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 478                                 if (wcp_file_size_change(fsp) == -1) {
 479                                         return -1;
 480                                 }
 481                         }
 482
 483                         /*
 484                          * If we used all the data then
 485                          * return here.
 486                          */
 487
 488                         if(n == data_used) {
 489                                 return n;
 490                         } else {
 491                                 cache_flush_needed = True;
 492                         }
 493                         /*
 494                          * Move the start of data forward by the amount used,
 495                          * cut down the amount left by the same amount.
 496                          */
 497
 498                         data += data_used;
 499                         pos += data_used;
 500                         n -= data_used;
 501
 502                         DO_PROFILE_INC(writecache_abutted_writes);
 503                         total_written = data_used;
 504
 505                         write_path = 1;
 506
 507                 } else if ((pos < wcp->offset) && (pos + n > wcp->offset) &&
 508                                         (pos + n <= wcp->offset + wcp->alloc_size)) {
 509
 510                         /* ASCII art.... JRA.
 511
 512                         +---------------+
 513                         | Cache buffer  |
 514                         +---------------+
 515
 516             +-------------------+
 517             | Data to write     |
 518             +-------------------+
 519
 520                         */
 521
 522                         /*
 523                          * End of write overlaps the existing data.
 524                          */
 525
 526                         size_t data_used = pos + n - wcp->offset;
 527
 528                         memcpy(wcp->data, data + n - data_used, data_used);
 529
 530                         /*
 531                          * Update the current buffer size with the new data.
 532                          */
 533
 534                         if(pos + n > wcp->offset + wcp->data_size) {
 535                                 wcp->data_size = pos + n - wcp->offset;
 536                         }
 537
 538                         /*
 539                          * Update the file size if changed.
 540                          */
 541
 542                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 543                                 if (wcp_file_size_change(fsp) == -1) {
 544                                         return -1;
 545                                 }
 546                         }
 547
 548                         /*
 549                          * We don't need to move the start of data, but we
 550                          * cut down the amount left by the amount used.
 551                          */
 552
 553                         n -= data_used;
 554
 555                         /*
 556                          * We cannot have used all the data here.
 557                          */
 558
 559                         cache_flush_needed = True;
 560
 561                         DO_PROFILE_INC(writecache_abutted_writes);
 562                         total_written = data_used;
 563
 564                         write_path = 2;
 565
 566                 } else if ( (pos >= wcp->file_size) &&
 567                                         (wcp->offset + wcp->data_size == wcp->file_size) &&
 568                                         (pos > wcp->offset + wcp->data_size) &&
 569                                         (pos < wcp->offset + wcp->alloc_size) ) {
 570
 571                         /* ASCII art.... JRA.
 572
 573                        End of file ---->|
 574
 575                         +---------------+---------------+
 576                         | Cached data   | Cache buffer  |
 577                         +---------------+---------------+
 578
 579                                               +-------------------+
 580                                               | Data to write     |
 581                                               +-------------------+
 582
 583                         */
 584
 585                         /*
 586                          * Non-contiguous write part of which fits within
 587                          * the cache buffer and is extending the file
 588                          * and the cache contents reflect the current
 589                          * data up to the current end of the file.
 590                          */
 591
 592                         size_t data_used;
 593
 594                         if(pos + n <= wcp->offset + wcp->alloc_size) {
 595                                 data_used = n;
 596                         } else {
 597                                 data_used = wcp->offset + wcp->alloc_size - pos;
 598                         }
 599
 600                         /*
 601                          * Fill in the non-continuous area with zeros.
 602                          */
 603
 604                         memset(wcp->data + wcp->data_size, '\0',
 605                                 pos - (wcp->offset + wcp->data_size) );
 606
 607                         memcpy(wcp->data + (pos - wcp->offset), data, data_used);
 608
 609                         /*
 610                          * Update the current buffer size with the new data.
 611                          */
 612
 613                         if(pos + data_used > wcp->offset + wcp->data_size) {
 614                                 wcp->data_size = pos + data_used - wcp->offset;
 615                         }
 616
 617                         /*
 618                          * Update the file size if changed.
 619                          */
 620
 621                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 622                                 if (wcp_file_size_change(fsp) == -1) {
 623                                         return -1;
 624                                 }
 625                         }
 626
 627                         /*
 628                          * If we used all the data then
 629                          * return here.
 630                          */
 631
 632                         if(n == data_used) {
 633                                 return n;
 634                         } else {
 635                                 cache_flush_needed = True;
 636                         }
 637
 638                         /*
 639                          * Move the start of data forward by the amount used,
 640                          * cut down the amount left by the same amount.
 641                          */
 642
 643                         data += data_used;
 644                         pos += data_used;
 645                         n -= data_used;
 646
 647                         DO_PROFILE_INC(writecache_abutted_writes);
 648                         total_written = data_used;
 649
 650                         write_path = 3;
 651
 652                 } else if ( (pos >= wcp->file_size) &&
 653                             (n == 1) &&
 654                             (wcp->file_size == wcp->offset + wcp->data_size) &&
 655                             (pos < wcp->file_size + wcp->alloc_size)) {
 656
 657                         /*
 658
 659                 End of file ---->|
 660
 661                  +---------------+---------------+
 662                  | Cached data   | Cache buffer  |
 663                  +---------------+---------------+
 664
 665                                  |<------- allocated size ---------------->|
 666
 667                                                          +--------+
 668                                                          | 1 Byte |
 669                                                          +--------+
 670
 671                         MS-Office seems to do this a lot to determine if there's enough
 672                         space on the filesystem to write a new file.
 673
 674                         Change to :
 675
 676                 End of file ---->|
 677                                  +-----------------------+--------+
 678                                  | Zeroed Cached data    | 1 Byte |
 679                                  +-----------------------+--------+
 680                         */
 681
 682                         flush_write_cache(fsp, WRITE_FLUSH);
 683                         wcp->offset = wcp->file_size;
 684                         wcp->data_size = pos - wcp->file_size + 1;
 685                         memset(wcp->data, '\0', wcp->data_size);
 686                         memcpy(wcp->data + wcp->data_size-1, data, 1);
 687
 688                         /*
 689                          * Update the file size if changed.
 690                          */
 691
 692                         if (wcp->offset + wcp->data_size > wcp->file_size) {
 693                                 if (wcp_file_size_change(fsp) == -1) {
 694                                         return -1;
 695                                 }
 696                         }
 697
 698                         return n;
 699
 700                 } else {
 701
 702                         /* ASCII art..... JRA.
 703
 704    Case 1).
 705
 706                         +---------------+---------------+
 707                         | Cached data   | Cache buffer  |
 708                         +---------------+---------------+
 709
 710                                                               +-------------------+
 711                                                               | Data to write     |
 712                                                               +-------------------+
 713
 714    Case 2).
 715
 716                            +---------------+---------------+
 717                            | Cached data   | Cache buffer  |
 718                            +---------------+---------------+
 719
 720    +-------------------+
 721    | Data to write     |
 722    +-------------------+
 723
 724     Case 3).
 725
 726                            +---------------+---------------+
 727                            | Cached data   | Cache buffer  |
 728                            +---------------+---------------+
 729
 730                   +-----------------------------------------------------+
 731                   | Data to write                                       |
 732                   +-----------------------------------------------------+
 733
 734                   */
 735
 736                         /*
 737                          * Write is bigger than buffer, or there is no overlap on the
 738                          * low or high ends.
 739                          */
 740
 741                         DEBUG(9,("write_file: non cacheable write : fd = %d, pos = %.0f, len = %u, current cache pos = %.0f \
 742 len = %u\n",fsp->fh->fd, (double)pos, (unsigned int)n, (double)wcp->offset, (unsigned int)wcp->data_size ));
 743
 744                         /*
 745                          * If write would fit in the cache, and is larger than
 746                          * the data already in the cache, flush the cache and
 747                          * preferentially copy the data new data into it. Otherwise
 748                          * just write the data directly.
 749                          */
 750
 751                         if ( n <= wcp->alloc_size && n > wcp->data_size) {
 752                                 cache_flush_needed = True;
 753                         } else {
 754                                 ssize_t ret = real_write_file(NULL,fsp, data, pos, n);
 755
 756                                 /*
 757                                  * If the write overlaps the entire cache, then
 758                                  * discard the current contents of the cache.
 759                                  * Fix from Rasmus Borup Hansen rbh@math.ku.dk.
 760                                  */
 761
 762                                 if ((pos <= wcp->offset) &&
 763                                                 (pos + n >= wcp->offset + wcp->data_size) ) {
 764                                         DEBUG(9,("write_file: discarding overwritten write \
 765 cache: fd = %d, off=%.0f, size=%u\n", fsp->fh->fd, (double)wcp->offset, (unsigned int)wcp->data_size ));
 766                                         wcp->data_size = 0;
 767                                 }
 768
 769                                 DO_PROFILE_INC(writecache_direct_writes);
 770                                 if (ret == -1) {
 771                                         return ret;
 772                                 }
 773
 774                                 if (pos + ret > wcp->file_size) {
 775                                         wcp->file_size = pos + ret;
 776                                 }
 777
 778                                 return ret;
 779                         }
 780
 781                         write_path = 4;
 782
 783                 }
 784
 785                 if (cache_flush_needed) {
 786                         DEBUG(3,("WRITE_FLUSH:%d: due to noncontinuous write: fd = %d, size = %.0f, pos = %.0f, \
 787 n = %u, wcp->offset=%.0f, wcp->data_size=%u\n",
 788                                 write_path, fsp->fh->fd, (double)wcp->file_size, (double)pos, (unsigned int)n,
 789                                 (double)wcp->offset, (unsigned int)wcp->data_size ));
 790
 791                         flush_write_cache(fsp, WRITE_FLUSH);
 792                 }
 793         }
 794
 795         /*
 796          * If the write request is bigger than the cache
 797          * size, write it all out.
 798          */
 799
 800         if (n > wcp->alloc_size ) {
 801                 ssize_t ret = real_write_file(NULL,fsp, data, pos, n);
 802                 if (ret == -1) {
 803                         return -1;
 804                 }
 805
 806                 if (pos + ret > wcp->file_size) {
 807                         wcp->file_size = pos + n;
 808                 }
 809
 810                 DO_PROFILE_INC(writecache_direct_writes);
 811                 return total_written + n;
 812         }
 813
 814         /*
 815          * If there's any data left, cache it.
 816          */
 817
 818         if (n) {
 819 #ifdef WITH_PROFILE
 820                 if (wcp->data_size) {
 821                         DO_PROFILE_INC(writecache_abutted_writes);
 822                 } else {
 823                         DO_PROFILE_INC(writecache_init_writes);
 824                 }
 825 #endif
 826
 827                 if ((wcp->data_size == 0)
 828                     && (pos > wcp->file_size)
 829                     && (pos + n <= wcp->file_size + wcp->alloc_size)) {
 830                         /*
 831                          * This is a write completely beyond the
 832                          * current EOF, but within reach of the write
 833                          * cache. We expect fill-up writes pretty
 834                          * soon, so it does not make sense to start
 835                          * the write cache at the current
 836                          * offset. These fill-up writes would trigger
 837                          * separate pwrites or even unnecessary cache
 838                          * flushes because they overlap if this is a
 839                          * one-byte allocating write.
 840                          */
 841                         wcp->offset = wcp->file_size;
 842                         wcp->data_size = pos - wcp->file_size;
 843                         memset(wcp->data, 0, wcp->data_size);
 844                 }
 845
 846                 memcpy(wcp->data+wcp->data_size, data, n);
 847                 if (wcp->data_size == 0) {
 848                         wcp->offset = pos;
 849                         DO_PROFILE_INC(writecache_num_write_caches);
 850                 }
 851                 wcp->data_size += n;
 852
 853                 /*
 854                  * Update the file size if changed.
 855                  */
 856
 857                 if (wcp->offset + wcp->data_size > wcp->file_size) {
 858                         if (wcp_file_size_change(fsp) == -1) {
 859                                 return -1;
 860                         }
 861                 }
 862                 DEBUG(9,("wcp->offset = %.0f wcp->data_size = %u cache return %u\n",
 863                         (double)wcp->offset, (unsigned int)wcp->data_size, (unsigned int)n));
 864
 865                 total_written += n;
 866                 return total_written; /* .... that's a write :) */
 867         }
 868
 869         return total_written;
 870 }
 871
 872 /****************************************************************************
 873  Delete the write cache structure.
 874 ****************************************************************************/
 875
 876 void delete_write_cache(files_struct *fsp)
 877 {
 878         write_cache *wcp;
 879
 880         if(!fsp) {
 881                 return;
 882         }
 883
 884         if(!(wcp = fsp->wcp)) {
 885                 return;
 886         }
 887
 888         DO_PROFILE_DEC(writecache_allocated_write_caches);
 889         allocated_write_caches--;
 890
 891         SMB_ASSERT(wcp->data_size == 0);
 892
 893         SAFE_FREE(wcp->data);
 894         SAFE_FREE(fsp->wcp);
 895
 896         DEBUG(10,("delete_write_cache: File %s deleted write cache\n",
 897                   fsp_str_dbg(fsp)));
 898 }
 899
 900 /****************************************************************************
 901  Setup the write cache structure.
 902 ****************************************************************************/
 903
 904 static bool setup_write_cache(files_struct *fsp, SMB_OFF_T file_size)
 905 {
 906         ssize_t alloc_size = lp_write_cache_size(SNUM(fsp->conn));
 907         write_cache *wcp;
 908
 909         if (allocated_write_caches >= MAX_WRITE_CACHES) {
 910                 return False;
 911         }
 912
 913         if(alloc_size == 0 || fsp->wcp) {
 914                 return False;
 915         }
 916
 917         if((wcp = SMB_MALLOC_P(write_cache)) == NULL) {
 918                 DEBUG(0,("setup_write_cache: malloc fail.\n"));
 919                 return False;
 920         }
 921
 922         wcp->file_size = file_size;
 923         wcp->offset = 0;
 924         wcp->alloc_size = alloc_size;
 925         wcp->data_size = 0;
 926         if((wcp->data = (char *)SMB_MALLOC(wcp->alloc_size)) == NULL) {
 927                 DEBUG(0,("setup_write_cache: malloc fail for buffer size %u.\n",
 928                         (unsigned int)wcp->alloc_size ));
 929                 SAFE_FREE(wcp);
 930                 return False;
 931         }
 932
 933         memset(wcp->data, '\0', wcp->alloc_size );
 934
 935         fsp->wcp = wcp;
 936         DO_PROFILE_INC(writecache_allocated_write_caches);
 937         allocated_write_caches++;
 938
 939         DEBUG(10,("setup_write_cache: File %s allocated write cache size %lu\n",
 940                   fsp_str_dbg(fsp), (unsigned long)wcp->alloc_size));
 941
 942         return True;
 943 }
 944
 945 /****************************************************************************
 946  Cope with a size change.
 947 ****************************************************************************/
 948
 949 void set_filelen_write_cache(files_struct *fsp, SMB_OFF_T file_size)
 950 {
 951         if(fsp->wcp) {
 952                 /* The cache *must* have been flushed before we do this. */
 953                 if (fsp->wcp->data_size != 0) {
 954                         char *msg;
 955                         if (asprintf(&msg, "set_filelen_write_cache: size change "
 956                                  "on file %s with write cache size = %lu\n",
 957                                  fsp->fsp_name->base_name,
 958                                  (unsigned long)fsp->wcp->data_size) != -1) {
 959                                 smb_panic(msg);
 960                         } else {
 961                                 smb_panic("set_filelen_write_cache");
 962                         }
 963                 }
 964                 fsp->wcp->file_size = file_size;
 965         }
 966 }
 967
 968 /*******************************************************************
 969  Flush a write cache struct to disk.
 970 ********************************************************************/
 971
 972 ssize_t flush_write_cache(files_struct *fsp, enum flush_reason_enum reason)
 973 {
 974         write_cache *wcp = fsp->wcp;
 975         size_t data_size;
 976         ssize_t ret;
 977
 978         if(!wcp || !wcp->data_size) {
 979                 return 0;
 980         }
 981
 982         data_size = wcp->data_size;
 983         wcp->data_size = 0;
 984
 985         DO_PROFILE_DEC_INC(writecache_num_write_caches,writecache_flushed_writes[reason]);
 986
 987         DEBUG(9,("flushing write cache: fd = %d, off=%.0f, size=%u\n",
 988                 fsp->fh->fd, (double)wcp->offset, (unsigned int)data_size));
 989
 990 #ifdef WITH_PROFILE
 991         if(data_size == wcp->alloc_size) {
 992                 DO_PROFILE_INC(writecache_num_perfect_writes);
 993         }
 994 #endif
 995
 996         ret = real_write_file(NULL, fsp, wcp->data, wcp->offset, data_size);
 997
 998         /*
 999          * Ensure file size if kept up to date if write extends file.
1000          */
1001
1002         if ((ret != -1) && (wcp->offset + ret > wcp->file_size)) {
1003                 wcp->file_size = wcp->offset + ret;
1004         }
1005
1006         return ret;
1007 }
1008
1009 /*******************************************************************
1010 sync a file
1011 ********************************************************************/
1012
1013 NTSTATUS sync_file(connection_struct *conn, files_struct *fsp, bool write_through)
1014 {
1015         if (fsp->fh->fd == -1)
1016                 return NT_STATUS_INVALID_HANDLE;
1017
1018         if (lp_strict_sync(SNUM(conn)) &&
1019             (lp_syncalways(SNUM(conn)) || write_through)) {
1020                 int ret = flush_write_cache(fsp, SYNC_FLUSH);
1021                 if (ret == -1) {
1022                         return map_nt_error_from_unix(errno);
1023                 }
1024                 ret = SMB_VFS_FSYNC(fsp);
1025                 if (ret == -1) {
1026                         return map_nt_error_from_unix(errno);
1027                 }
1028         }
1029         return NT_STATUS_OK;
1030 }
1031
1032 /************************************************************
1033  Perform a stat whether a valid fd or not.
1034 ************************************************************/
1035
1036 int fsp_stat(files_struct *fsp)
1037 {
1038         if (fsp->fh->fd == -1) {
1039                 if (fsp->posix_open) {
1040                         return SMB_VFS_LSTAT(fsp->conn, fsp->fsp_name);
1041                 } else {
1042                         return SMB_VFS_STAT(fsp->conn, fsp->fsp_name);
1043                 }
1044         } else {
1045                 return SMB_VFS_FSTAT(fsp, &fsp->fsp_name->st);
1046         }
1047 }