external/bsd/openldap/dist/servers/slapd/alock.c

   1 /* alock.c - access lock library */
   2 /* $OpenLDAP: pkg/ldap/servers/slapd/alock.c,v 1.5.2.7 2008/02/11 23:26:43 kurt Exp $ */
   3 /* This work is part of OpenLDAP Software <http://www.openldap.org/>.
   4  *
   5  * Copyright 2005-2008 The OpenLDAP Foundation.
   6  * Portions Copyright 2004-2005 Symas Corporation.
   7  * All rights reserved.
   8  *
   9  * Redistribution and use in source and binary forms, with or without
  10  * modification, are permitted only as authorized by the OpenLDAP
  11  * Public License.
  12  *
  13  * A copy of this license is available in the file LICENSE in the
  14  * top-level directory of the distribution or, alternatively, at
  15  * <http://www.OpenLDAP.org/license.html>.
  16  */
  17 /* ACKNOWLEDGEMENTS:
  18  * This work was initially developed by Matthew Backes at Symas
  19  * Corporation for inclusion in OpenLDAP Software.
  20  */
  21
  22 #include "portable.h"
  23
  24 #if SLAPD_BDB || SLAPD_HDB
  25
  26 #include "alock.h"
  27
  28 #include <ac/stdlib.h>
  29 #include <ac/string.h>
  30 #include <ac/unistd.h>
  31 #include <ac/errno.h>
  32 #include <ac/assert.h>
  33 #include <sys/types.h>
  34 #include <sys/stat.h>
  35 #ifdef HAVE_SYS_FILE_H
  36 #include <sys/file.h>
  37 #endif
  38 #include <fcntl.h>
  39
  40 #ifdef _WIN32
  41 #include <stdio.h>
  42 #include <io.h>
  43 #include <sys/locking.h>
  44 #endif
  45
  46
  47 static int
  48 alock_grab_lock ( int fd, int slot )
  49 {
  50         int res;
  51
  52 #if defined( HAVE_LOCKF )
  53         res = lseek (fd, (off_t) (ALOCK_SLOT_SIZE * slot), SEEK_SET);
  54         if (res == -1) return -1;
  55         res = lockf (fd, F_LOCK, (off_t) ALOCK_SLOT_SIZE);
  56 #elif defined( HAVE_FCNTL )
  57         struct flock lock_info;
  58         (void) memset ((void *) &lock_info, 0, sizeof (struct flock));
  59
  60         lock_info.l_type = F_WRLCK;
  61         lock_info.l_whence = SEEK_SET;
  62         lock_info.l_start = (off_t) (ALOCK_SLOT_SIZE * slot);
  63         lock_info.l_len = (off_t) ALOCK_SLOT_SIZE;
  64
  65         res = fcntl (fd, F_SETLKW, &lock_info);
  66 #elif defined( _WIN32 )
  67         if( _lseek( fd, (ALOCK_SLOT_SIZE * slot), SEEK_SET ) < 0 )
  68                 return -1;
  69         /*
  70          * _lock will try for the lock once per second, returning EDEADLOCK
  71          * after ten tries. We just loop until we either get the lock
  72          * or some other error is returned.
  73          */
  74         while((res = _locking( fd, _LK_LOCK, ALOCK_SLOT_SIZE )) < 0 ) {
  75                 if( errno != EDEADLOCK )
  76                         break;
  77         }
  78 #else
  79 #   error alock needs lockf, fcntl, or _locking
  80 #endif
  81         if (res == -1) {
  82                 assert (errno != EDEADLK);
  83                 return -1;
  84         }
  85         return 0;
  86 }
  87
  88 static int
  89 alock_release_lock ( int fd, int slot )
  90 {
  91         int res;
  92
  93 #if defined( HAVE_LOCKF )
  94         res = lseek (fd, (off_t) (ALOCK_SLOT_SIZE * slot), SEEK_SET);
  95         if (res == -1) return -1;
  96         res = lockf (fd, F_ULOCK, (off_t) ALOCK_SLOT_SIZE);
  97         if (res == -1) return -1;
  98 #elif defined ( HAVE_FCNTL )
  99         struct flock lock_info;
 100         (void) memset ((void *) &lock_info, 0, sizeof (struct flock));
 101
 102         lock_info.l_type = F_UNLCK;
 103         lock_info.l_whence = SEEK_SET;
 104         lock_info.l_start = (off_t) (ALOCK_SLOT_SIZE * slot);
 105         lock_info.l_len = (off_t) ALOCK_SLOT_SIZE;
 106
 107         res = fcntl (fd, F_SETLKW, &lock_info);
 108         if (res == -1) return -1;
 109 #elif defined( _WIN32 )
 110         res = _lseek (fd, (ALOCK_SLOT_SIZE * slot), SEEK_SET);
 111         if (res == -1) return -1;
 112         res = _locking( fd, _LK_UNLCK, ALOCK_SLOT_SIZE );
 113         if (res == -1) return -1;
 114 #else
 115 #   error alock needs lockf, fcntl, or _locking
 116 #endif
 117
 118         return 0;
 119 }
 120
 121 static int
 122 alock_test_lock ( int fd, int slot )
 123 {
 124         int res;
 125
 126 #if defined( HAVE_LOCKF )
 127         res = lseek (fd, (off_t) (ALOCK_SLOT_SIZE * slot), SEEK_SET);
 128         if (res == -1) return -1;
 129
 130         res = lockf (fd, F_TEST, (off_t) ALOCK_SLOT_SIZE);
 131         if (res == -1) {
 132                 if (errno == EACCES || errno == EAGAIN) {
 133                         return ALOCK_LOCKED;
 134                 } else {
 135                         return -1;
 136                 }
 137         }
 138 #elif defined( HAVE_FCNTL )
 139         struct flock lock_info;
 140         (void) memset ((void *) &lock_info, 0, sizeof (struct flock));
 141
 142         lock_info.l_type = F_WRLCK;
 143         lock_info.l_whence = SEEK_SET;
 144         lock_info.l_start = (off_t) (ALOCK_SLOT_SIZE * slot);
 145         lock_info.l_len = (off_t) ALOCK_SLOT_SIZE;
 146
 147         res = fcntl (fd, F_GETLK, &lock_info);
 148         if (res == -1) return -1;
 149
 150         if (lock_info.l_type != F_UNLCK) return ALOCK_LOCKED;
 151 #elif defined( _WIN32 )
 152         res = _lseek (fd, (ALOCK_SLOT_SIZE * slot), SEEK_SET);
 153         if (res == -1) return -1;
 154         res = _locking( fd, _LK_NBLCK, ALOCK_SLOT_SIZE );
 155         _locking( fd, _LK_UNLCK, ALOCK_SLOT_SIZE );
 156         if (res == -1) {
 157            if( errno == EACCES ) {
 158                    return ALOCK_LOCKED;
 159            } else {
 160                    return -1;
 161            }
 162         }
 163 #else
 164 #   error alock needs lockf, fcntl, or _locking
 165 #endif
 166
 167         return 0;
 168 }
 169
 170 /* Read a 64bit LE value */
 171 static unsigned long int
 172 alock_read_iattr ( unsigned char * bufptr )
 173 {
 174         unsigned long int val = 0;
 175         int count;
 176
 177         assert (bufptr != NULL);
 178
 179         bufptr += sizeof (unsigned long int);
 180         for (count=0; count <= sizeof (unsigned long int); ++count) {
 181                 val <<= 8;
 182                 val += (unsigned long int) *bufptr--;
 183         }
 184
 185         return val;
 186 }
 187
 188 /* Write a 64bit LE value */
 189 static void
 190 alock_write_iattr ( unsigned char * bufptr,
 191                     unsigned long int val )
 192 {
 193         int count;
 194
 195         assert (bufptr != NULL);
 196
 197         for (count=0; count < 8; ++count) {
 198                 *bufptr++ = (unsigned char) (val & 0xff);
 199                 val >>= 8;
 200         }
 201 }
 202
 203 static int
 204 alock_read_slot ( alock_info_t * info,
 205                   alock_slot_t * slot_data )
 206 {
 207         unsigned char slotbuf [ALOCK_SLOT_SIZE];
 208         int res, size, size_total, err;
 209
 210         assert (info != NULL);
 211         assert (slot_data != NULL);
 212         assert (info->al_slot > 0);
 213
 214         res = lseek (info->al_fd,
 215                      (off_t) (ALOCK_SLOT_SIZE * info->al_slot),
 216                      SEEK_SET);
 217         if (res == -1) return -1;
 218
 219         size_total = 0;
 220         while (size_total < ALOCK_SLOT_SIZE) {
 221                 size = read (info->al_fd,
 222                              slotbuf + size_total,
 223                              ALOCK_SLOT_SIZE - size_total);
 224                 if (size == 0) return -1;
 225                 if (size < 0) {
 226                         err = errno;
 227                         if (err != EINTR && err != EAGAIN) return -1;
 228                 } else {
 229                         size_total += size;
 230                 }
 231         }
 232
 233         if (alock_read_iattr (slotbuf) != ALOCK_MAGIC) {
 234                 return -1;
 235         }
 236         slot_data->al_lock  = alock_read_iattr (slotbuf+8);
 237         slot_data->al_stamp = alock_read_iattr (slotbuf+16);
 238         slot_data->al_pid   = alock_read_iattr (slotbuf+24);
 239
 240         if (slot_data->al_appname) free (slot_data->al_appname);
 241         slot_data->al_appname = calloc (1, ALOCK_MAX_APPNAME);
 242         strncpy (slot_data->al_appname, (char *)slotbuf+32, ALOCK_MAX_APPNAME-1);
 243         (slot_data->al_appname) [ALOCK_MAX_APPNAME-1] = '\0';
 244
 245         return 0;
 246 }
 247
 248 static int
 249 alock_write_slot ( alock_info_t * info,
 250                    alock_slot_t * slot_data )
 251 {
 252         unsigned char slotbuf [ALOCK_SLOT_SIZE];
 253         int res, size, size_total, err;
 254
 255         assert (info != NULL);
 256         assert (slot_data != NULL);
 257         assert (info->al_slot > 0);
 258
 259         (void) memset ((void *) slotbuf, 0, ALOCK_SLOT_SIZE);
 260
 261         alock_write_iattr (slotbuf,    ALOCK_MAGIC);
 262         assert (alock_read_iattr (slotbuf) == ALOCK_MAGIC);
 263         alock_write_iattr (slotbuf+8,  slot_data->al_lock);
 264         alock_write_iattr (slotbuf+16, slot_data->al_stamp);
 265         alock_write_iattr (slotbuf+24, slot_data->al_pid);
 266
 267         if (slot_data->al_appname)
 268                 strncpy ((char *)slotbuf+32, slot_data->al_appname, ALOCK_MAX_APPNAME-1);
 269         slotbuf[ALOCK_SLOT_SIZE-1] = '\0';
 270
 271         res = lseek (info->al_fd,
 272                      (off_t) (ALOCK_SLOT_SIZE * info->al_slot),
 273                      SEEK_SET);
 274         if (res == -1) return -1;
 275
 276         size_total = 0;
 277         while (size_total < ALOCK_SLOT_SIZE) {
 278                 size = write (info->al_fd,
 279                               slotbuf + size_total,
 280                               ALOCK_SLOT_SIZE - size_total);
 281                 if (size == 0) return -1;
 282                 if (size < 0) {
 283                         err = errno;
 284                         if (err != EINTR && err != EAGAIN) return -1;
 285                 } else {
 286                         size_total += size;
 287                 }
 288         }
 289
 290         return 0;
 291 }
 292
 293 static int
 294 alock_query_slot ( alock_info_t * info )
 295 {
 296         int res, nosave;
 297         alock_slot_t slot_data;
 298
 299         assert (info != NULL);
 300         assert (info->al_slot > 0);
 301
 302         (void) memset ((void *) &slot_data, 0, sizeof (alock_slot_t));
 303         alock_read_slot (info, &slot_data);
 304
 305         if (slot_data.al_appname != NULL) free (slot_data.al_appname);
 306         slot_data.al_appname = NULL;
 307
 308         nosave = slot_data.al_lock & ALOCK_NOSAVE;
 309
 310         if ((slot_data.al_lock & ALOCK_SMASK) == ALOCK_UNLOCKED)
 311                 return slot_data.al_lock;
 312
 313         res = alock_test_lock (info->al_fd, info->al_slot);
 314         if (res < 0) return -1;
 315         if (res > 0) {
 316                 if ((slot_data.al_lock & ALOCK_SMASK) == ALOCK_UNIQUE) {
 317                         return slot_data.al_lock;
 318                 } else {
 319                         return ALOCK_LOCKED | nosave;
 320                 }
 321         }
 322
 323         return ALOCK_DIRTY | nosave;
 324 }
 325
 326 int
 327 alock_open ( alock_info_t * info,
 328              const char * appname,
 329              const char * envdir,
 330              int locktype )
 331 {
 332         struct stat statbuf;
 333         alock_info_t scan_info;
 334         alock_slot_t slot_data;
 335         char * filename;
 336         int res, max_slot;
 337         int dirty_count, live_count, nosave;
 338
 339         assert (info != NULL);
 340         assert (appname != NULL);
 341         assert (envdir != NULL);
 342         assert ((locktype & ALOCK_SMASK) >= 1 && (locktype & ALOCK_SMASK) <= 2);
 343
 344         slot_data.al_lock = locktype;
 345         slot_data.al_stamp = time(NULL);
 346         slot_data.al_pid = getpid();
 347         slot_data.al_appname = calloc (1, ALOCK_MAX_APPNAME);
 348         strncpy (slot_data.al_appname, appname, ALOCK_MAX_APPNAME-1);
 349         slot_data.al_appname [ALOCK_MAX_APPNAME-1] = '\0';
 350
 351         filename = calloc (1, strlen (envdir) + strlen ("/alock") + 1);
 352         strcpy (filename, envdir);
 353         strcat (filename, "/alock");
 354         info->al_fd = open (filename, O_CREAT|O_RDWR, 0666);
 355         free (filename);
 356         if (info->al_fd < 0) {
 357                 free (slot_data.al_appname);
 358                 return ALOCK_UNSTABLE;
 359         }
 360         info->al_slot = 0;
 361
 362         res = alock_grab_lock (info->al_fd, 0);
 363         if (res == -1) {
 364                 close (info->al_fd);
 365                 free (slot_data.al_appname);
 366                 return ALOCK_UNSTABLE;
 367         }
 368
 369         res = fstat (info->al_fd, &statbuf);
 370         if (res == -1) {
 371                 close (info->al_fd);
 372                 free (slot_data.al_appname);
 373                 return ALOCK_UNSTABLE;
 374         }
 375
 376         max_slot = (statbuf.st_size + ALOCK_SLOT_SIZE - 1) / ALOCK_SLOT_SIZE;
 377         dirty_count = 0;
 378         live_count = 0;
 379         nosave = 0;
 380         scan_info.al_fd = info->al_fd;
 381         for (scan_info.al_slot = 1;
 382              scan_info.al_slot < max_slot;
 383              ++ scan_info.al_slot) {
 384                 if (scan_info.al_slot != info->al_slot) {
 385                         res = alock_query_slot (&scan_info);
 386
 387                         if (res & ALOCK_NOSAVE) {
 388                                 nosave = ALOCK_NOSAVE;
 389                                 res ^= ALOCK_NOSAVE;
 390                         }
 391                         if (res == ALOCK_UNLOCKED
 392                             && info->al_slot == 0) {
 393                                 info->al_slot = scan_info.al_slot;
 394
 395                         } else if (res == ALOCK_LOCKED) {
 396                                 ++live_count;
 397
 398                         } else if (res == ALOCK_UNIQUE
 399                                 && locktype == ALOCK_UNIQUE) {
 400                                 close (info->al_fd);
 401                                 free (slot_data.al_appname);
 402                                 return ALOCK_BUSY;
 403
 404                         } else if (res == ALOCK_DIRTY) {
 405                                 ++dirty_count;
 406
 407                         } else if (res == -1) {
 408                                 close (info->al_fd);
 409                                 free (slot_data.al_appname);
 410                                 return ALOCK_UNSTABLE;
 411
 412                         }
 413                 }
 414         }
 415
 416         if (dirty_count && live_count) {
 417                 close (info->al_fd);
 418                 free (slot_data.al_appname);
 419                 return ALOCK_UNSTABLE;
 420         }
 421
 422         if (info->al_slot == 0) info->al_slot = max_slot + 1;
 423         res = alock_grab_lock (info->al_fd,
 424                                info->al_slot);
 425         if (res == -1) {
 426                 close (info->al_fd);
 427                 free (slot_data.al_appname);
 428                 return ALOCK_UNSTABLE;
 429         }
 430         res = alock_write_slot (info, &slot_data);
 431         free (slot_data.al_appname);
 432         if (res == -1) {
 433                 close (info->al_fd);
 434                 return ALOCK_UNSTABLE;
 435         }
 436
 437         res = alock_release_lock (info->al_fd, 0);
 438         if (res == -1) {
 439                 close (info->al_fd);
 440                 return ALOCK_UNSTABLE;
 441         }
 442
 443         if (dirty_count) return ALOCK_RECOVER | nosave;
 444         return ALOCK_CLEAN | nosave;
 445 }
 446
 447 int
 448 alock_scan ( alock_info_t * info )
 449 {
 450         struct stat statbuf;
 451         alock_info_t scan_info;
 452         int res, max_slot;
 453         int dirty_count, live_count, nosave;
 454
 455         assert (info != NULL);
 456
 457         scan_info.al_fd = info->al_fd;
 458
 459         res = alock_grab_lock (info->al_fd, 0);
 460         if (res == -1) {
 461                 close (info->al_fd);
 462                 return ALOCK_UNSTABLE;
 463         }
 464
 465         res = fstat (info->al_fd, &statbuf);
 466         if (res == -1) {
 467                 close (info->al_fd);
 468                 return ALOCK_UNSTABLE;
 469         }
 470
 471         max_slot = (statbuf.st_size + ALOCK_SLOT_SIZE - 1) / ALOCK_SLOT_SIZE;
 472         dirty_count = 0;
 473         live_count = 0;
 474         nosave = 0;
 475         for (scan_info.al_slot = 1;
 476              scan_info.al_slot < max_slot;
 477              ++ scan_info.al_slot) {
 478                 if (scan_info.al_slot != info->al_slot) {
 479                         res = alock_query_slot (&scan_info);
 480
 481                         if (res & ALOCK_NOSAVE) {
 482                                 nosave = ALOCK_NOSAVE;
 483                                 res ^= ALOCK_NOSAVE;
 484                         }
 485
 486                         if (res == ALOCK_LOCKED) {
 487                                 ++live_count;
 488
 489                         } else if (res == ALOCK_DIRTY) {
 490                                 ++dirty_count;
 491
 492                         } else if (res == -1) {
 493                                 close (info->al_fd);
 494                                 return ALOCK_UNSTABLE;
 495
 496                         }
 497                 }
 498         }
 499
 500         res = alock_release_lock (info->al_fd, 0);
 501         if (res == -1) {
 502                 close (info->al_fd);
 503                 return ALOCK_UNSTABLE;
 504         }
 505
 506         if (dirty_count) {
 507                 if (live_count) {
 508                         close (info->al_fd);
 509                         return ALOCK_UNSTABLE;
 510                 } else {
 511                         return ALOCK_RECOVER | nosave;
 512                 }
 513         }
 514
 515         return ALOCK_CLEAN | nosave;
 516 }
 517
 518 int
 519 alock_close ( alock_info_t * info, int nosave )
 520 {
 521         alock_slot_t slot_data;
 522         int res;
 523
 524         if ( !info->al_slot )
 525                 return ALOCK_CLEAN;
 526
 527         (void) memset ((void *) &slot_data, 0, sizeof(alock_slot_t));
 528
 529         res = alock_grab_lock (info->al_fd, 0);
 530         if (res == -1) {
 531                 close (info->al_fd);
 532                 return ALOCK_UNSTABLE;
 533         }
 534
 535         /* mark our slot as clean */
 536         res = alock_read_slot (info, &slot_data);
 537         if (res == -1) {
 538                 close (info->al_fd);
 539                 if (slot_data.al_appname != NULL)
 540                         free (slot_data.al_appname);
 541                 return ALOCK_UNSTABLE;
 542         }
 543         slot_data.al_lock = ALOCK_UNLOCKED;
 544         if ( nosave )
 545                 slot_data.al_lock |= ALOCK_NOSAVE;
 546         res = alock_write_slot (info, &slot_data);
 547         if (res == -1) {
 548                 close (info->al_fd);
 549                 if (slot_data.al_appname != NULL)
 550                         free (slot_data.al_appname);
 551                 return ALOCK_UNSTABLE;
 552         }
 553         if (slot_data.al_appname != NULL) {
 554                 free (slot_data.al_appname);
 555                 slot_data.al_appname = NULL;
 556         }
 557
 558         res = alock_release_lock (info->al_fd, info->al_slot);
 559         if (res == -1) {
 560                 close (info->al_fd);
 561                 return ALOCK_UNSTABLE;
 562         }
 563         res = alock_release_lock (info->al_fd, 0);
 564         if (res == -1) {
 565                 close (info->al_fd);
 566                 return ALOCK_UNSTABLE;
 567         }
 568
 569         res = close (info->al_fd);
 570         if (res == -1) return ALOCK_UNSTABLE;
 571
 572         return ALOCK_CLEAN;
 573 }
 574
 575 int
 576 alock_recover ( alock_info_t * info )
 577 {
 578         struct stat statbuf;
 579         alock_slot_t slot_data;
 580         alock_info_t scan_info;
 581         int res, max_slot;
 582
 583         assert (info != NULL);
 584
 585         scan_info.al_fd = info->al_fd;
 586
 587         (void) memset ((void *) &slot_data, 0, sizeof(alock_slot_t));
 588
 589         res = alock_grab_lock (info->al_fd, 0);
 590         if (res == -1) {
 591                 close (info->al_fd);
 592                 return ALOCK_UNSTABLE;
 593         }
 594
 595         res = fstat (info->al_fd, &statbuf);
 596         if (res == -1) {
 597                 close (info->al_fd);
 598                 return ALOCK_UNSTABLE;
 599         }
 600
 601         max_slot = (statbuf.st_size + ALOCK_SLOT_SIZE - 1) / ALOCK_SLOT_SIZE;
 602         for (scan_info.al_slot = 1;
 603              scan_info.al_slot < max_slot;
 604              ++ scan_info.al_slot) {
 605                 if (scan_info.al_slot != info->al_slot) {
 606                         res = alock_query_slot (&scan_info) & ~ALOCK_NOSAVE;
 607
 608                         if (res == ALOCK_LOCKED
 609                             || res == ALOCK_UNIQUE) {
 610                                 /* recovery attempt on an active db? */
 611                                 close (info->al_fd);
 612                                 return ALOCK_UNSTABLE;
 613
 614                         } else if (res == ALOCK_DIRTY) {
 615                                 /* mark it clean */
 616                                 res = alock_read_slot (&scan_info, &slot_data);
 617                                 if (res == -1) {
 618                                         close (info->al_fd);
 619                                         return ALOCK_UNSTABLE;
 620                                 }
 621                                 slot_data.al_lock = ALOCK_UNLOCKED;
 622                                 res = alock_write_slot (&scan_info, &slot_data);
 623                                 if (res == -1) {
 624                                         close (info->al_fd);
 625                                         if (slot_data.al_appname != NULL)
 626                                                 free (slot_data.al_appname);
 627                                         return ALOCK_UNSTABLE;
 628                                 }
 629                                 if (slot_data.al_appname != NULL) {
 630                                         free (slot_data.al_appname);
 631                                         slot_data.al_appname = NULL;
 632                                 }
 633
 634                         } else if (res == -1) {
 635                                 close (info->al_fd);
 636                                 return ALOCK_UNSTABLE;
 637
 638                         }
 639                 }
 640         }
 641
 642         res = alock_release_lock (info->al_fd, 0);
 643         if (res == -1) {
 644                 close (info->al_fd);
 645                 return ALOCK_UNSTABLE;
 646         }
 647
 648         return ALOCK_CLEAN;
 649 }
 650
 651 #endif /* SLAPD_BDB || SLAPD_HDB */