git.ozlabs.org Git - ccan/blob - ccan/tdb2/tdb1_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 "tdb1_private.h"
  30 #ifndef MAX
  31 #define MAX(a,b) ((a) > (b) ? (a) : (b))
  32 #endif
  33
  34 /* check for an out of bounds access - if it is out of bounds then
  35    see if the database has been expanded by someone else and expand
  36    if necessary
  37    note that "len" is the minimum length needed for the db
  38 */
  39 static int tdb1_oob(struct tdb_context *tdb, tdb1_off_t len, int probe)
  40 {
  41         struct stat st;
  42         if (len <= tdb->file->map_size)
  43                 return 0;
  44         if (tdb->flags & TDB_INTERNAL) {
  45                 if (!probe) {
  46                         tdb->last_error = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
  47                                                 "tdb1_oob len %d beyond internal malloc size %d",
  48                                                 (int)len, (int)tdb->file->map_size);
  49                 }
  50                 return -1;
  51         }
  52
  53         if (fstat(tdb->file->fd, &st) == -1) {
  54                 tdb->last_error = TDB_ERR_IO;
  55                 return -1;
  56         }
  57
  58         if (st.st_size < (size_t)len) {
  59                 if (!probe) {
  60                         tdb->last_error = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
  61                                                 "tdb1_oob len %d beyond eof at %d",
  62                                                 (int)len, (int)st.st_size);
  63                 }
  64                 return -1;
  65         }
  66
  67         /* Unmap, update size, remap */
  68         if (tdb1_munmap(tdb) == -1) {
  69                 tdb->last_error = TDB_ERR_IO;
  70                 return -1;
  71         }
  72         tdb->file->map_size = st.st_size;
  73         tdb1_mmap(tdb);
  74         return 0;
  75 }
  76
  77 /* write a lump of data at a specified offset */
  78 static int tdb1_write(struct tdb_context *tdb, tdb1_off_t off,
  79                      const void *buf, tdb1_len_t len)
  80 {
  81         if (len == 0) {
  82                 return 0;
  83         }
  84
  85         if ((tdb->flags & TDB_RDONLY) || tdb->tdb1.traverse_read) {
  86                 tdb->last_error = TDB_ERR_RDONLY;
  87                 return -1;
  88         }
  89
  90         if (tdb->tdb1.io->tdb1_oob(tdb, off + len, 0) != 0)
  91                 return -1;
  92
  93         if (tdb->file->map_ptr) {
  94                 memcpy(off + (char *)tdb->file->map_ptr, buf, len);
  95         } else {
  96                 ssize_t written = pwrite(tdb->file->fd, buf, len, off);
  97                 if ((written != (ssize_t)len) && (written != -1)) {
  98                         tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_WARNING,
  99                                    "tdb1_write: wrote only "
 100                                    "%d of %d bytes at %d, trying once more",
 101                                    (int)written, len, off);
 102                         written = pwrite(tdb->file->fd,
 103                                          (const char *)buf+written,
 104                                          len-written,
 105                                          off+written);
 106                 }
 107                 if (written == -1) {
 108                         /* Ensure ecode is set for log fn. */
 109                         tdb->last_error = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
 110                                                 "tdb1_write failed at %d "
 111                                                 "len=%d (%s)",
 112                                                 off, len, strerror(errno));
 113                         return -1;
 114                 } else if (written != (ssize_t)len) {
 115                         tdb->last_error = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
 116                                                 "tdb1_write: failed to "
 117                                                 "write %d bytes at %d in two attempts",
 118                                                 len, off);
 119                         return -1;
 120                 }
 121         }
 122         return 0;
 123 }
 124
 125 /* Endian conversion: we only ever deal with 4 byte quantities */
 126 void *tdb1_convert(void *buf, uint32_t size)
 127 {
 128         uint32_t i, *p = (uint32_t *)buf;
 129         for (i = 0; i < size / 4; i++)
 130                 p[i] = TDB1_BYTEREV(p[i]);
 131         return buf;
 132 }
 133
 134
 135 /* read a lump of data at a specified offset, maybe convert */
 136 static int tdb1_read(struct tdb_context *tdb, tdb1_off_t off, void *buf,
 137                     tdb1_len_t len, int cv)
 138 {
 139         if (tdb->tdb1.io->tdb1_oob(tdb, off + len, 0) != 0) {
 140                 return -1;
 141         }
 142
 143         if (tdb->file->map_ptr) {
 144                 memcpy(buf, off + (char *)tdb->file->map_ptr, len);
 145         } else {
 146                 ssize_t ret = pread(tdb->file->fd, buf, len, off);
 147                 if (ret != (ssize_t)len) {
 148                         /* Ensure ecode is set for log fn. */
 149                         tdb->last_error = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
 150                                                 "tdb1_read failed at %d "
 151                                                 "len=%d ret=%d (%s) map_size=%d",
 152                                                 (int)off, (int)len, (int)ret,
 153                                                 strerror(errno),
 154                                                 (int)tdb->file->map_size);
 155                         return -1;
 156                 }
 157         }
 158         if (cv) {
 159                 tdb1_convert(buf, len);
 160         }
 161         return 0;
 162 }
 163
 164
 165
 166 /*
 167   do an unlocked scan of the hash table heads to find the next non-zero head. The value
 168   will then be confirmed with the lock held
 169 */
 170 static void tdb1_next_hash_chain(struct tdb_context *tdb, uint32_t *chain)
 171 {
 172         uint32_t h = *chain;
 173         if (tdb->file->map_ptr) {
 174                 for (;h < tdb->tdb1.header.hash_size;h++) {
 175                         if (0 != *(uint32_t *)(TDB1_HASH_TOP(h) + (unsigned char *)tdb->file->map_ptr)) {
 176                                 break;
 177                         }
 178                 }
 179         } else {
 180                 uint32_t off=0;
 181                 for (;h < tdb->tdb1.header.hash_size;h++) {
 182                         if (tdb1_ofs_read(tdb, TDB1_HASH_TOP(h), &off) != 0 || off != 0) {
 183                                 break;
 184                         }
 185                 }
 186         }
 187         (*chain) = h;
 188 }
 189
 190
 191 int tdb1_munmap(struct tdb_context *tdb)
 192 {
 193         if (tdb->flags & TDB_INTERNAL)
 194                 return 0;
 195
 196 #if HAVE_MMAP
 197         if (tdb->file->map_ptr) {
 198                 int ret;
 199
 200                 ret = munmap(tdb->file->map_ptr, tdb->file->map_size);
 201                 if (ret != 0)
 202                         return ret;
 203         }
 204 #endif
 205         tdb->file->map_ptr = NULL;
 206         return 0;
 207 }
 208
 209 void tdb1_mmap(struct tdb_context *tdb)
 210 {
 211         if (tdb->flags & TDB_INTERNAL)
 212                 return;
 213
 214 #if HAVE_MMAP
 215         if (!(tdb->flags & TDB_NOMMAP)) {
 216                 int mmap_flags;
 217                 if ((tdb->open_flags & O_ACCMODE) == O_RDONLY)
 218                         mmap_flags = PROT_READ;
 219                 else
 220                         mmap_flags = PROT_READ | PROT_WRITE;
 221
 222                 tdb->file->map_ptr = mmap(NULL, tdb->file->map_size,
 223                                     mmap_flags,
 224                                     MAP_SHARED|MAP_FILE, tdb->file->fd, 0);
 225
 226                 /*
 227                  * NB. When mmap fails it returns MAP_FAILED *NOT* NULL !!!!
 228                  */
 229
 230                 if (tdb->file->map_ptr == MAP_FAILED) {
 231                         tdb->file->map_ptr = NULL;
 232                         tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_WARNING,
 233                                    "tdb1_mmap failed for size %d (%s)",
 234                                    tdb->file->map_size, strerror(errno));
 235                 }
 236         } else {
 237                 tdb->file->map_ptr = NULL;
 238         }
 239 #else
 240         tdb->file->map_ptr = NULL;
 241 #endif
 242 }
 243
 244 /* expand a file.  we prefer to use ftruncate, as that is what posix
 245   says to use for mmap expansion */
 246 static int tdb1_expand_file(struct tdb_context *tdb, tdb1_off_t size, tdb1_off_t addition)
 247 {
 248         char buf[8192];
 249
 250         if ((tdb->flags & TDB_RDONLY) || tdb->tdb1.traverse_read) {
 251                 tdb->last_error = TDB_ERR_RDONLY;
 252                 return -1;
 253         }
 254
 255         if (ftruncate(tdb->file->fd, size+addition) == -1) {
 256                 char b = 0;
 257                 ssize_t written = pwrite(tdb->file->fd, &b, 1,
 258                                          (size+addition) - 1);
 259                 if (written == 0) {
 260                         /* try once more, potentially revealing errno */
 261                         written = pwrite(tdb->file->fd, &b, 1,
 262                                          (size+addition) - 1);
 263                 }
 264                 if (written == 0) {
 265                         /* again - give up, guessing errno */
 266                         errno = ENOSPC;
 267                 }
 268                 if (written != 1) {
 269                         tdb->last_error = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
 270                                                 "expand_file to %d failed (%s)",
 271                                                 size+addition,
 272                                                 strerror(errno));
 273                         return -1;
 274                 }
 275         }
 276
 277         /* now fill the file with something. This ensures that the
 278            file isn't sparse, which would be very bad if we ran out of
 279            disk. This must be done with write, not via mmap */
 280         memset(buf, TDB1_PAD_BYTE, sizeof(buf));
 281         while (addition) {
 282                 size_t n = addition>sizeof(buf)?sizeof(buf):addition;
 283                 ssize_t written = pwrite(tdb->file->fd, buf, n, size);
 284                 if (written == 0) {
 285                         /* prevent infinite loops: try _once_ more */
 286                         written = pwrite(tdb->file->fd, buf, n, size);
 287                 }
 288                 if (written == 0) {
 289                         /* give up, trying to provide a useful errno */
 290                         tdb->last_error = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
 291                                                 "expand_file write "
 292                                                 "returned 0 twice: giving up!");
 293                         errno = ENOSPC;
 294                         return -1;
 295                 } else if (written == -1) {
 296                         tdb->last_error = tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_ERROR,
 297                                                 "expand_file write of "
 298                                                 "%d bytes failed (%s)", (int)n,
 299                                                 strerror(errno));
 300                         return -1;
 301                 } else if (written != n) {
 302                         tdb_logerr(tdb, TDB_ERR_IO, TDB_LOG_WARNING,
 303                                    "expand_file: wrote "
 304                                    "only %d of %d bytes - retrying",
 305                                    (int)written, (int)n);
 306                 }
 307                 addition -= written;
 308                 size += written;
 309         }
 310         return 0;
 311 }
 312
 313
 314 /* expand the database at least size bytes by expanding the underlying
 315    file and doing the mmap again if necessary */
 316 int tdb1_expand(struct tdb_context *tdb, tdb1_off_t size)
 317 {
 318         struct tdb1_record rec;
 319         tdb1_off_t offset, new_size, top_size, map_size;
 320
 321         if (tdb1_lock(tdb, -1, F_WRLCK) == -1) {
 322                 tdb_logerr(tdb, tdb->last_error, TDB_LOG_ERROR,
 323                            "lock failed in tdb1_expand");
 324                 return -1;
 325         }
 326
 327         /* must know about any previous expansions by another process */
 328         tdb->tdb1.io->tdb1_oob(tdb, tdb->file->map_size + 1, 1);
 329
 330         /* limit size in order to avoid using up huge amounts of memory for
 331          * in memory tdbs if an oddball huge record creeps in */
 332         if (size > 100 * 1024) {
 333                 top_size = tdb->file->map_size + size * 2;
 334         } else {
 335                 top_size = tdb->file->map_size + size * 100;
 336         }
 337
 338         /* always make room for at least top_size more records, and at
 339            least 25% more space. if the DB is smaller than 100MiB,
 340            otherwise grow it by 10% only. */
 341         if (tdb->file->map_size > 100 * 1024 * 1024) {
 342                 map_size = tdb->file->map_size * 1.10;
 343         } else {
 344                 map_size = tdb->file->map_size * 1.25;
 345         }
 346
 347         /* Round the database up to a multiple of the page size */
 348         new_size = MAX(top_size, map_size);
 349         size = TDB1_ALIGN(new_size, tdb->tdb1.page_size) - tdb->file->map_size;
 350
 351         if (!(tdb->flags & TDB_INTERNAL))
 352                 tdb1_munmap(tdb);
 353
 354         /*
 355          * We must ensure the file is unmapped before doing this
 356          * to ensure consistency with systems like OpenBSD where
 357          * writes and mmaps are not consistent.
 358          */
 359
 360         /* expand the file itself */
 361         if (!(tdb->flags & TDB_INTERNAL)) {
 362                 if (tdb->tdb1.io->tdb1_expand_file(tdb, tdb->file->map_size, size) != 0)
 363                         goto fail;
 364         }
 365
 366         tdb->file->map_size += size;
 367
 368         if (tdb->flags & TDB_INTERNAL) {
 369                 char *new_map_ptr = (char *)realloc(tdb->file->map_ptr,
 370                                                     tdb->file->map_size);
 371                 if (!new_map_ptr) {
 372                         tdb->file->map_size -= size;
 373                         goto fail;
 374                 }
 375                 tdb->file->map_ptr = new_map_ptr;
 376         } else {
 377                 /*
 378                  * We must ensure the file is remapped before adding the space
 379                  * to ensure consistency with systems like OpenBSD where
 380                  * writes and mmaps are not consistent.
 381                  */
 382
 383                 /* We're ok if the mmap fails as we'll fallback to read/write */
 384                 tdb1_mmap(tdb);
 385         }
 386
 387         /* form a new freelist record */
 388         memset(&rec,'\0',sizeof(rec));
 389         rec.rec_len = size - sizeof(rec);
 390
 391         /* link it into the free list */
 392         offset = tdb->file->map_size - size;
 393         if (tdb1_free(tdb, offset, &rec) == -1)
 394                 goto fail;
 395
 396         tdb1_unlock(tdb, -1, F_WRLCK);
 397         return 0;
 398  fail:
 399         tdb1_unlock(tdb, -1, F_WRLCK);
 400         return -1;
 401 }
 402
 403 /* read/write a tdb1_off_t */
 404 int tdb1_ofs_read(struct tdb_context *tdb, tdb1_off_t offset, tdb1_off_t *d)
 405 {
 406         return tdb->tdb1.io->tdb1_read(tdb, offset, (char*)d, sizeof(*d), TDB1_DOCONV());
 407 }
 408
 409 int tdb1_ofs_write(struct tdb_context *tdb, tdb1_off_t offset, tdb1_off_t *d)
 410 {
 411         tdb1_off_t off = *d;
 412         return tdb->tdb1.io->tdb1_write(tdb, offset, TDB1_CONV(off), sizeof(*d));
 413 }
 414
 415
 416 /* read a lump of data, allocating the space for it */
 417 unsigned char *tdb1_alloc_read(struct tdb_context *tdb, tdb1_off_t offset, tdb1_len_t len)
 418 {
 419         unsigned char *buf;
 420
 421         /* some systems don't like zero length malloc */
 422
 423         if (!(buf = (unsigned char *)malloc(len ? len : 1))) {
 424                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_OOM, TDB_LOG_ERROR,
 425                                              "tdb1_alloc_read malloc failed"
 426                                              " len=%d (%s)",
 427                                              len, strerror(errno));
 428                 return NULL;
 429         }
 430         if (tdb->tdb1.io->tdb1_read(tdb, offset, buf, len, 0) == -1) {
 431                 SAFE_FREE(buf);
 432                 return NULL;
 433         }
 434         return buf;
 435 }
 436
 437 /* Give a piece of tdb data to a parser */
 438 enum TDB_ERROR tdb1_parse_data(struct tdb_context *tdb, TDB_DATA key,
 439                                tdb1_off_t offset, tdb1_len_t len,
 440                                enum TDB_ERROR (*parser)(TDB_DATA key,
 441                                                         TDB_DATA data,
 442                                                         void *private_data),
 443                                void *private_data)
 444 {
 445         TDB_DATA data;
 446         enum TDB_ERROR result;
 447
 448         data.dsize = len;
 449
 450         if ((tdb->tdb1.transaction == NULL) && (tdb->file->map_ptr != NULL)) {
 451                 /*
 452                  * Optimize by avoiding the malloc/memcpy/free, point the
 453                  * parser directly at the mmap area.
 454                  */
 455                 if (tdb->tdb1.io->tdb1_oob(tdb, offset+len, 0) != 0) {
 456                         return tdb->last_error;
 457                 }
 458                 data.dptr = offset + (unsigned char *)tdb->file->map_ptr;
 459                 return parser(key, data, private_data);
 460         }
 461
 462         if (!(data.dptr = tdb1_alloc_read(tdb, offset, len))) {
 463                 return tdb->last_error;
 464         }
 465
 466         result = parser(key, data, private_data);
 467         free(data.dptr);
 468         return result;
 469 }
 470
 471 /* read/write a record */
 472 int tdb1_rec_read(struct tdb_context *tdb, tdb1_off_t offset, struct tdb1_record *rec)
 473 {
 474         if (tdb->tdb1.io->tdb1_read(tdb, offset, rec, sizeof(*rec),TDB1_DOCONV()) == -1)
 475                 return -1;
 476         if (TDB1_BAD_MAGIC(rec)) {
 477                 tdb->last_error = tdb_logerr(tdb, TDB_ERR_CORRUPT, TDB_LOG_ERROR,
 478                                         "tdb1_rec_read bad magic 0x%x at offset=%d",
 479                                         rec->magic, offset);
 480                 return -1;
 481         }
 482         return tdb->tdb1.io->tdb1_oob(tdb, rec->next+sizeof(*rec), 0);
 483 }
 484
 485 int tdb1_rec_write(struct tdb_context *tdb, tdb1_off_t offset, struct tdb1_record *rec)
 486 {
 487         struct tdb1_record r = *rec;
 488         return tdb->tdb1.io->tdb1_write(tdb, offset, TDB1_CONV(r), sizeof(r));
 489 }
 490
 491 static const struct tdb1_methods io1_methods = {
 492         tdb1_read,
 493         tdb1_write,
 494         tdb1_next_hash_chain,
 495         tdb1_oob,
 496         tdb1_expand_file,
 497 };
 498
 499 /*
 500   initialise the default methods table
 501 */
 502 void tdb1_io_init(struct tdb_context *tdb)
 503 {
 504         tdb->tdb1.io = &io1_methods;
 505 }
 506
 507 enum TDB_ERROR tdb1_probe_length(struct tdb_context *tdb)
 508 {
 509         tdb->last_error = TDB_SUCCESS;
 510         tdb->tdb1.io->tdb1_oob(tdb, tdb->file->map_size + 1, true);
 511         return tdb->last_error;
 512 }