lib/tdb/common/io.c

   1  /*
   2    Unix SMB/CIFS implementation.
   3
   4    trivial database library
   5
   6    Copyright (C) Andrew Tridgell              1999-2005
   7    Copyright (C) Paul `Rusty' Russell              2000
   8    Copyright (C) Jeremy Allison                    2000-2003
   9
  10      ** NOTE! The following LGPL license applies to the tdb
  11      ** library. This does NOT imply that all of Samba is released
  12      ** under the LGPL
  13
  14    This library is free software; you can redistribute it and/or
  15    modify it under the terms of the GNU Lesser General Public
  16    License as published by the Free Software Foundation; either
  17    version 3 of the License, or (at your option) any later version.
  18
  19    This library is distributed in the hope that it will be useful,
  20    but WITHOUT ANY WARRANTY; without even the implied warranty of
  21    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  22    Lesser General Public License for more details.
  23
  24    You should have received a copy of the GNU Lesser General Public
  25    License along with this library; if not, see <http://www.gnu.org/licenses/>.
  26 */
  27
  28
  29 #include "tdb_private.h"
  30
  31 /* check for an out of bounds access - if it is out of bounds then
  32    see if the database has been expanded by someone else and expand
  33    if necessary
  34 */
  35 static int tdb_oob(struct tdb_context *tdb, tdb_off_t off, tdb_len_t len,
  36                    int probe)
  37 {
  38         struct stat st;
  39         if (len + off < len) {
  40                 if (!probe) {
  41                         /* Ensure ecode is set for log fn. */
  42                         tdb->ecode = TDB_ERR_IO;
  43                         TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_oob off %u len %u wrap\n",
  44                                  off, len));
  45                 }
  46                 return -1;
  47         }
  48
  49         if (off + len <= tdb->map_size)
  50                 return 0;
  51         if (tdb->flags & TDB_INTERNAL) {
  52                 if (!probe) {
  53                         /* Ensure ecode is set for log fn. */
  54                         tdb->ecode = TDB_ERR_IO;
  55                         TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_oob len %u beyond internal malloc size %u\n",
  56                                  (int)(off + len), (int)tdb->map_size));
  57                 }
  58                 return -1;
  59         }
  60
  61         if (fstat(tdb->fd, &st) == -1) {
  62                 tdb->ecode = TDB_ERR_IO;
  63                 return -1;
  64         }
  65
  66         /* Beware >4G files! */
  67         if ((tdb_off_t)st.st_size != st.st_size) {
  68                 /* Ensure ecode is set for log fn. */
  69                 tdb->ecode = TDB_ERR_IO;
  70                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_oob len %llu too large!\n",
  71                          (long long)st.st_size));
  72                 return -1;
  73         }
  74
  75         /* Unmap, update size, remap.  We do this unconditionally, to handle
  76          * the unusual case where the db is truncated.
  77          *
  78          * This can happen to a child using tdb_reopen_all(true) on a
  79          * TDB_CLEAR_IF_FIRST tdb whose parent crashes: the next
  80          * opener will truncate the database. */
  81         if (tdb_munmap(tdb) == -1) {
  82                 tdb->ecode = TDB_ERR_IO;
  83                 return -1;
  84         }
  85         tdb->map_size = st.st_size;
  86         if (tdb_mmap(tdb) != 0) {
  87                 return -1;
  88         }
  89
  90         if (st.st_size < (size_t)off + len) {
  91                 if (!probe) {
  92                         /* Ensure ecode is set for log fn. */
  93                         tdb->ecode = TDB_ERR_IO;
  94                         TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_oob len %u beyond eof at %u\n",
  95                                  (int)(off + len), (int)st.st_size));
  96                 }
  97                 return -1;
  98         }
  99         return 0;
 100 }
 101
 102 /* write a lump of data at a specified offset */
 103 static int tdb_write(struct tdb_context *tdb, tdb_off_t off,
 104                      const void *buf, tdb_len_t len)
 105 {
 106         if (len == 0) {
 107                 return 0;
 108         }
 109
 110         if (tdb->read_only || tdb->traverse_read) {
 111                 tdb->ecode = TDB_ERR_RDONLY;
 112                 return -1;
 113         }
 114
 115         if (tdb->methods->tdb_oob(tdb, off, len, 0) != 0)
 116                 return -1;
 117
 118         if (tdb->map_ptr) {
 119                 memcpy(off + (char *)tdb->map_ptr, buf, len);
 120         } else {
 121 #ifdef HAVE_INCOHERENT_MMAP
 122                 tdb->ecode = TDB_ERR_IO;
 123                 return -1;
 124 #else
 125                 ssize_t written = pwrite(tdb->fd, buf, len, off);
 126                 if ((written != (ssize_t)len) && (written != -1)) {
 127                         /* try once more */
 128                         tdb->ecode = TDB_ERR_IO;
 129                         TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_write: wrote only "
 130                                  "%zi of %u bytes at %u, trying once more\n",
 131                                  written, len, off));
 132                         written = pwrite(tdb->fd, (const char *)buf+written,
 133                                          len-written,
 134                                          off+written);
 135                 }
 136                 if (written == -1) {
 137                         /* Ensure ecode is set for log fn. */
 138                         tdb->ecode = TDB_ERR_IO;
 139                         TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_write failed at %u "
 140                                  "len=%u (%s)\n", off, len, strerror(errno)));
 141                         return -1;
 142                 } else if (written != (ssize_t)len) {
 143                         tdb->ecode = TDB_ERR_IO;
 144                         TDB_LOG((tdb, TDB_DEBUG_FATAL, "tdb_write: failed to "
 145                                  "write %u bytes at %u in two attempts\n",
 146                                  len, off));
 147                         return -1;
 148                 }
 149 #endif
 150         }
 151         return 0;
 152 }
 153
 154 /* Endian conversion: we only ever deal with 4 byte quantities */
 155 void *tdb_convert(void *buf, uint32_t size)
 156 {
 157         uint32_t i, *p = (uint32_t *)buf;
 158         for (i = 0; i < size / 4; i++)
 159                 p[i] = TDB_BYTEREV(p[i]);
 160         return buf;
 161 }
 162
 163
 164 /* read a lump of data at a specified offset, maybe convert */
 165 static int tdb_read(struct tdb_context *tdb, tdb_off_t off, void *buf,
 166                     tdb_len_t len, int cv)
 167 {
 168         if (tdb->methods->tdb_oob(tdb, off, len, 0) != 0) {
 169                 return -1;
 170         }
 171
 172         if (tdb->map_ptr) {
 173                 memcpy(buf, off + (char *)tdb->map_ptr, len);
 174         } else {
 175 #ifdef HAVE_INCOHERENT_MMAP
 176                 tdb->ecode = TDB_ERR_IO;
 177                 return -1;
 178 #else
 179                 ssize_t ret = pread(tdb->fd, buf, len, off);
 180                 if (ret != (ssize_t)len) {
 181                         /* Ensure ecode is set for log fn. */
 182                         tdb->ecode = TDB_ERR_IO;
 183                         TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_read failed at %u "
 184                                  "len=%u ret=%zi (%s) map_size=%u\n",
 185                                  off, len, ret, strerror(errno),
 186                                  tdb->map_size));
 187                         return -1;
 188                 }
 189 #endif
 190         }
 191         if (cv) {
 192                 tdb_convert(buf, len);
 193         }
 194         return 0;
 195 }
 196
 197
 198
 199 /*
 200   do an unlocked scan of the hash table heads to find the next non-zero head. The value
 201   will then be confirmed with the lock held
 202 */
 203 static void tdb_next_hash_chain(struct tdb_context *tdb, uint32_t *chain)
 204 {
 205         uint32_t h = *chain;
 206         if (tdb->map_ptr) {
 207                 for (;h < tdb->hash_size;h++) {
 208                         if (0 != *(uint32_t *)(TDB_HASH_TOP(h) + (unsigned char *)tdb->map_ptr)) {
 209                                 break;
 210                         }
 211                 }
 212         } else {
 213                 uint32_t off=0;
 214                 for (;h < tdb->hash_size;h++) {
 215                         if (tdb_ofs_read(tdb, TDB_HASH_TOP(h), &off) != 0 || off != 0) {
 216                                 break;
 217                         }
 218                 }
 219         }
 220         (*chain) = h;
 221 }
 222
 223
 224 int tdb_munmap(struct tdb_context *tdb)
 225 {
 226         if (tdb->flags & TDB_INTERNAL)
 227                 return 0;
 228
 229 #ifdef HAVE_MMAP
 230         if (tdb->map_ptr) {
 231                 int ret;
 232
 233                 ret = munmap(tdb->map_ptr, tdb->map_size);
 234                 if (ret != 0)
 235                         return ret;
 236         }
 237 #endif
 238         tdb->map_ptr = NULL;
 239         return 0;
 240 }
 241
 242 /* If mmap isn't coherent, *everyone* must always mmap. */
 243 static bool should_mmap(const struct tdb_context *tdb)
 244 {
 245 #ifdef HAVE_INCOHERENT_MMAP
 246         return true;
 247 #else
 248         return !(tdb->flags & TDB_NOMMAP);
 249 #endif
 250 }
 251
 252 int tdb_mmap(struct tdb_context *tdb)
 253 {
 254         if (tdb->flags & TDB_INTERNAL)
 255                 return 0;
 256
 257 #ifdef HAVE_MMAP
 258         if (should_mmap(tdb)) {
 259                 tdb->map_ptr = mmap(NULL, tdb->map_size,
 260                                     PROT_READ|(tdb->read_only? 0:PROT_WRITE),
 261                                     MAP_SHARED|MAP_FILE, tdb->fd, 0);
 262
 263                 /*
 264                  * NB. When mmap fails it returns MAP_FAILED *NOT* NULL !!!!
 265                  */
 266
 267                 if (tdb->map_ptr == MAP_FAILED) {
 268                         tdb->map_ptr = NULL;
 269                         TDB_LOG((tdb, TDB_DEBUG_WARNING, "tdb_mmap failed for size %u (%s)\n",
 270                                  tdb->map_size, strerror(errno)));
 271 #ifdef HAVE_INCOHERENT_MMAP
 272                         tdb->ecode = TDB_ERR_IO;
 273                         return -1;
 274 #endif
 275                 }
 276         } else {
 277                 tdb->map_ptr = NULL;
 278         }
 279 #else
 280         tdb->map_ptr = NULL;
 281 #endif
 282         return 0;
 283 }
 284
 285 /* expand a file.  we prefer to use ftruncate, as that is what posix
 286   says to use for mmap expansion */
 287 static int tdb_expand_file(struct tdb_context *tdb, tdb_off_t size, tdb_off_t addition)
 288 {
 289         char buf[8192];
 290         tdb_off_t new_size;
 291
 292         if (tdb->read_only || tdb->traverse_read) {
 293                 tdb->ecode = TDB_ERR_RDONLY;
 294                 return -1;
 295         }
 296
 297         if (!tdb_add_off_t(size, addition, &new_size)) {
 298                 tdb->ecode = TDB_ERR_OOM;
 299                 TDB_LOG((tdb, TDB_DEBUG_FATAL, "expand_file write "
 300                         "overflow detected current size[%u] addition[%u]!\n",
 301                         (unsigned)size, (unsigned)addition));
 302                 errno = ENOSPC;
 303                 return -1;
 304         }
 305
 306         if (ftruncate(tdb->fd, new_size) == -1) {
 307                 char b = 0;
 308                 ssize_t written = pwrite(tdb->fd,  &b, 1, new_size - 1);
 309                 if (written == 0) {
 310                         /* try once more, potentially revealing errno */
 311                         written = pwrite(tdb->fd,  &b, 1, new_size - 1);
 312                 }
 313                 if (written == 0) {
 314                         /* again - give up, guessing errno */
 315                         errno = ENOSPC;
 316                 }
 317                 if (written != 1) {
 318                         tdb->ecode = TDB_ERR_OOM;
 319                         TDB_LOG((tdb, TDB_DEBUG_FATAL, "expand_file to %u failed (%s)\n",
 320                                  (unsigned)new_size, strerror(errno)));
 321                         return -1;
 322                 }
 323         }
 324
 325         /* now fill the file with something. This ensures that the
 326            file isn't sparse, which would be very bad if we ran out of
 327            disk. This must be done with write, not via mmap */
 328         memset(buf, TDB_PAD_BYTE, sizeof(buf));
 329         while (addition) {
 330                 size_t n = addition>sizeof(buf)?sizeof(buf):addition;
 331                 ssize_t written = pwrite(tdb->fd, buf, n, size);
 332                 if (written == 0) {
 333                         /* prevent infinite loops: try _once_ more */
 334                         written = pwrite(tdb->fd, buf, n, size);
 335                 }
 336                 if (written == 0) {
 337                         /* give up, trying to provide a useful errno */
 338                         tdb->ecode = TDB_ERR_OOM;
 339                         TDB_LOG((tdb, TDB_DEBUG_FATAL, "expand_file write "
 340                                 "returned 0 twice: giving up!\n"));
 341                         errno = ENOSPC;
 342                         return -1;
 343                 }
 344                 if (written == -1) {
 345                         tdb->ecode = TDB_ERR_OOM;
 346                         TDB_LOG((tdb, TDB_DEBUG_FATAL, "expand_file write of "
 347                                  "%u bytes failed (%s)\n", (int)n,
 348                                  strerror(errno)));
 349                         return -1;
 350                 }
 351                 if (written != n) {
 352                         TDB_LOG((tdb, TDB_DEBUG_WARNING, "expand_file: wrote "
 353                                  "only %zu of %zi bytes - retrying\n", written,
 354                                  n));
 355                 }
 356                 addition -= written;
 357                 size += written;
 358         }
 359         return 0;
 360 }
 361
 362
 363 /* You need 'size', this tells you how much you should expand by. */
 364 tdb_off_t tdb_expand_adjust(tdb_off_t map_size, tdb_off_t size, int page_size)
 365 {
 366         tdb_off_t new_size, top_size;
 367
 368         /* limit size in order to avoid using up huge amounts of memory for
 369          * in memory tdbs if an oddball huge record creeps in */
 370         if (size > 100 * 1024) {
 371                 top_size = map_size + size * 2;
 372         } else {
 373                 top_size = map_size + size * 100;
 374         }
 375
 376         /* always make room for at least top_size more records, and at
 377            least 25% more space. if the DB is smaller than 100MiB,
 378            otherwise grow it by 10% only. */
 379         if (map_size > 100 * 1024 * 1024) {
 380                 new_size = map_size * 1.10;
 381         } else {
 382                 new_size = map_size * 1.25;
 383         }
 384
 385         /* Round the database up to a multiple of the page size */
 386         new_size = MAX(top_size, new_size);
 387         return TDB_ALIGN(new_size, page_size) - map_size;
 388 }
 389
 390 /* expand the database at least size bytes by expanding the underlying
 391    file and doing the mmap again if necessary */
 392 int tdb_expand(struct tdb_context *tdb, tdb_off_t size)
 393 {
 394         struct tdb_record rec;
 395         tdb_off_t offset;
 396
 397         if (tdb_lock(tdb, -1, F_WRLCK) == -1) {
 398                 TDB_LOG((tdb, TDB_DEBUG_ERROR, "lock failed in tdb_expand\n"));
 399                 return -1;
 400         }
 401
 402         /* must know about any previous expansions by another process */
 403         tdb->methods->tdb_oob(tdb, tdb->map_size, 1, 1);
 404
 405         size = tdb_expand_adjust(tdb->map_size, size, tdb->page_size);
 406
 407         /* expand the file itself */
 408         if (!(tdb->flags & TDB_INTERNAL)) {
 409                 if (tdb->methods->tdb_expand_file(tdb, tdb->map_size, size) != 0)
 410                         goto fail;
 411         }
 412
 413         /* form a new freelist record */
 414         offset = tdb->map_size;
 415         memset(&rec,'\0',sizeof(rec));
 416         rec.rec_len = size - sizeof(rec);
 417
 418         if (tdb->flags & TDB_INTERNAL) {
 419                 char *new_map_ptr = (char *)realloc(tdb->map_ptr,
 420                                                     tdb->map_size + size);
 421                 if (!new_map_ptr) {
 422                         goto fail;
 423                 }
 424                 tdb->map_ptr = new_map_ptr;
 425                 tdb->map_size += size;
 426         } else {
 427                 /* Explicitly remap: if we're in a transaction, this won't
 428                  * happen automatically! */
 429                 tdb_munmap(tdb);
 430                 tdb->map_size += size;
 431                 if (tdb_mmap(tdb) != 0) {
 432                         goto fail;
 433                 }
 434         }
 435
 436         /* link it into the free list */
 437         if (tdb_free(tdb, offset, &rec) == -1)
 438                 goto fail;
 439
 440         tdb_unlock(tdb, -1, F_WRLCK);
 441         return 0;
 442  fail:
 443         tdb_unlock(tdb, -1, F_WRLCK);
 444         return -1;
 445 }
 446
 447 /* read/write a tdb_off_t */
 448 int tdb_ofs_read(struct tdb_context *tdb, tdb_off_t offset, tdb_off_t *d)
 449 {
 450         return tdb->methods->tdb_read(tdb, offset, (char*)d, sizeof(*d), DOCONV());
 451 }
 452
 453 int tdb_ofs_write(struct tdb_context *tdb, tdb_off_t offset, tdb_off_t *d)
 454 {
 455         tdb_off_t off = *d;
 456         return tdb->methods->tdb_write(tdb, offset, CONVERT(off), sizeof(*d));
 457 }
 458
 459
 460 /* read a lump of data, allocating the space for it */
 461 unsigned char *tdb_alloc_read(struct tdb_context *tdb, tdb_off_t offset, tdb_len_t len)
 462 {
 463         unsigned char *buf;
 464
 465         /* some systems don't like zero length malloc */
 466
 467         if (!(buf = (unsigned char *)malloc(len ? len : 1))) {
 468                 /* Ensure ecode is set for log fn. */
 469                 tdb->ecode = TDB_ERR_OOM;
 470                 TDB_LOG((tdb, TDB_DEBUG_ERROR,"tdb_alloc_read malloc failed len=%u (%s)\n",
 471                            len, strerror(errno)));
 472                 return NULL;
 473         }
 474         if (tdb->methods->tdb_read(tdb, offset, buf, len, 0) == -1) {
 475                 SAFE_FREE(buf);
 476                 return NULL;
 477         }
 478         return buf;
 479 }
 480
 481 /* Give a piece of tdb data to a parser */
 482
 483 int tdb_parse_data(struct tdb_context *tdb, TDB_DATA key,
 484                    tdb_off_t offset, tdb_len_t len,
 485                    int (*parser)(TDB_DATA key, TDB_DATA data,
 486                                  void *private_data),
 487                    void *private_data)
 488 {
 489         TDB_DATA data;
 490         int result;
 491
 492         data.dsize = len;
 493
 494         if ((tdb->transaction == NULL) && (tdb->map_ptr != NULL)) {
 495                 /*
 496                  * Optimize by avoiding the malloc/memcpy/free, point the
 497                  * parser directly at the mmap area.
 498                  */
 499                 if (tdb->methods->tdb_oob(tdb, offset, len, 0) != 0) {
 500                         return -1;
 501                 }
 502                 data.dptr = offset + (unsigned char *)tdb->map_ptr;
 503                 return parser(key, data, private_data);
 504         }
 505
 506         if (!(data.dptr = tdb_alloc_read(tdb, offset, len))) {
 507                 return -1;
 508         }
 509
 510         result = parser(key, data, private_data);
 511         free(data.dptr);
 512         return result;
 513 }
 514
 515 /* read/write a record */
 516 int tdb_rec_read(struct tdb_context *tdb, tdb_off_t offset, struct tdb_record *rec)
 517 {
 518         if (tdb->methods->tdb_read(tdb, offset, rec, sizeof(*rec),DOCONV()) == -1)
 519                 return -1;
 520         if (TDB_BAD_MAGIC(rec)) {
 521                 /* Ensure ecode is set for log fn. */
 522                 tdb->ecode = TDB_ERR_CORRUPT;
 523                 TDB_LOG((tdb, TDB_DEBUG_FATAL,"tdb_rec_read bad magic 0x%x at offset=%u\n", rec->magic, offset));
 524                 return -1;
 525         }
 526         return tdb->methods->tdb_oob(tdb, rec->next, sizeof(*rec), 0);
 527 }
 528
 529 int tdb_rec_write(struct tdb_context *tdb, tdb_off_t offset, struct tdb_record *rec)
 530 {
 531         struct tdb_record r = *rec;
 532         return tdb->methods->tdb_write(tdb, offset, CONVERT(r), sizeof(r));
 533 }
 534
 535 static const struct tdb_methods io_methods = {
 536         tdb_read,
 537         tdb_write,
 538         tdb_next_hash_chain,
 539         tdb_oob,
 540         tdb_expand_file,
 541 };
 542
 543 /*
 544   initialise the default methods table
 545 */
 546 void tdb_io_init(struct tdb_context *tdb)
 547 {
 548         tdb->methods = &io_methods;
 549 }