granicus.if.org Git - postgresql/blob - src/backend/utils/init/miscinit.c

   1 /*-------------------------------------------------------------------------
   2  *
   3  * miscinit.c
   4  *        miscellaneous initialization support stuff
   5  *
   6  * Portions Copyright (c) 1996-2003, PostgreSQL Global Development Group
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  *
  10  * IDENTIFICATION
  11  *        $Header: /cvsroot/pgsql/src/backend/utils/init/miscinit.c,v 1.114 2003/09/24 18:54:01 tgl Exp $
  12  *
  13  *-------------------------------------------------------------------------
  14  */
  15 #include "postgres.h"
  16
  17 #include <sys/param.h>
  18 #include <signal.h>
  19 #include <sys/file.h>
  20 #include <sys/stat.h>
  21 #include <sys/time.h>
  22 #include <fcntl.h>
  23 #include <unistd.h>
  24 #include <grp.h>
  25 #include <pwd.h>
  26 #include <errno.h>
  27 #include <netinet/in.h>
  28 #include <arpa/inet.h>
  29 #ifdef HAVE_UTIME_H
  30 #include <utime.h>
  31 #endif
  32
  33 #include "catalog/catname.h"
  34 #include "catalog/pg_shadow.h"
  35 #include "libpq/libpq-be.h"
  36 #include "miscadmin.h"
  37 #include "storage/ipc.h"
  38 #include "storage/pg_shmem.h"
  39 #include "utils/builtins.h"
  40 #include "utils/guc.h"
  41 #include "utils/lsyscache.h"
  42 #include "utils/syscache.h"
  43
  44
  45 ProcessingMode Mode = InitProcessing;
  46
  47 /* Note: we rely on these to initialize as zeroes */
  48 static char directoryLockFile[MAXPGPATH];
  49 static char socketLockFile[MAXPGPATH];
  50
  51
  52 /* ----------------------------------------------------------------
  53  *              ignoring system indexes support stuff
  54  *
  55  * NOTE: "ignoring system indexes" means we do not use the system indexes
  56  * for lookups (either in hardwired catalog accesses or in planner-generated
  57  * plans).  We do, however, still update the indexes when a catalog
  58  * modification is made.
  59  * ----------------------------------------------------------------
  60  */
  61
  62 static bool isIgnoringSystemIndexes = false;
  63
  64 /*
  65  * IsIgnoringSystemIndexes
  66  *              True if ignoring system indexes.
  67  */
  68 bool
  69 IsIgnoringSystemIndexes(void)
  70 {
  71         return isIgnoringSystemIndexes;
  72 }
  73
  74 /*
  75  * IgnoreSystemIndexes
  76  *              Set true or false whether PostgreSQL ignores system indexes.
  77  */
  78 void
  79 IgnoreSystemIndexes(bool mode)
  80 {
  81         isIgnoringSystemIndexes = mode;
  82 }
  83
  84 /* ----------------------------------------------------------------
  85  *              system index reindexing support
  86  *
  87  * When we are busy reindexing a system index, this code provides support
  88  * for preventing catalog lookups from using that index.
  89  * ----------------------------------------------------------------
  90  */
  91
  92 static Oid      currentlyReindexedHeap = InvalidOid;
  93 static Oid      currentlyReindexedIndex = InvalidOid;
  94
  95 /*
  96  * ReindexIsProcessingHeap
  97  *              True if heap specified by OID is currently being reindexed.
  98  */
  99 bool
 100 ReindexIsProcessingHeap(Oid heapOid)
 101 {
 102         return heapOid == currentlyReindexedHeap;
 103 }
 104
 105 /*
 106  * ReindexIsProcessingIndex
 107  *              True if index specified by OID is currently being reindexed.
 108  */
 109 bool
 110 ReindexIsProcessingIndex(Oid indexOid)
 111 {
 112         return indexOid == currentlyReindexedIndex;
 113 }
 114
 115 /*
 116  * SetReindexProcessing
 117  *              Set flag that specified heap/index are being reindexed.
 118  *              Pass InvalidOid to indicate that reindexing is not active.
 119  */
 120 void
 121 SetReindexProcessing(Oid heapOid, Oid indexOid)
 122 {
 123         /* Args should be both, or neither, InvalidOid */
 124         Assert((heapOid == InvalidOid) == (indexOid == InvalidOid));
 125         /* Reindexing is not re-entrant. */
 126         Assert(indexOid == InvalidOid || currentlyReindexedIndex == InvalidOid);
 127         currentlyReindexedHeap = heapOid;
 128         currentlyReindexedIndex = indexOid;
 129 }
 130
 131 /* ----------------------------------------------------------------
 132  *                              database path / name support stuff
 133  * ----------------------------------------------------------------
 134  */
 135
 136 void
 137 SetDatabasePath(const char *path)
 138 {
 139         if (DatabasePath)
 140         {
 141                 free(DatabasePath);
 142                 DatabasePath = NULL;
 143         }
 144         /* use strdup since this is done before memory contexts are set up */
 145         if (path)
 146         {
 147                 DatabasePath = strdup(path);
 148                 AssertState(DatabasePath);
 149         }
 150 }
 151
 152 /*
 153  * Set data directory, but make sure it's an absolute path.  Use this,
 154  * never set DataDir directly.
 155  */
 156 void
 157 SetDataDir(const char *dir)
 158 {
 159         char       *new;
 160         int                     newlen;
 161
 162         AssertArg(dir);
 163
 164         /* If presented path is relative, convert to absolute */
 165         if (!is_absolute_path(dir))
 166         {
 167                 char       *buf;
 168                 size_t          buflen;
 169
 170                 buflen = MAXPGPATH;
 171                 for (;;)
 172                 {
 173                         buf = malloc(buflen);
 174                         if (!buf)
 175                                 ereport(FATAL,
 176                                                 (errcode(ERRCODE_OUT_OF_MEMORY),
 177                                                  errmsg("out of memory")));
 178
 179                         if (getcwd(buf, buflen))
 180                                 break;
 181                         else if (errno == ERANGE)
 182                         {
 183                                 free(buf);
 184                                 buflen *= 2;
 185                                 continue;
 186                         }
 187                         else
 188                         {
 189                                 free(buf);
 190                                 elog(FATAL, "could not get current working directory: %m");
 191                         }
 192                 }
 193
 194                 new = malloc(strlen(buf) + 1 + strlen(dir) + 1);
 195                 if (!new)
 196                         ereport(FATAL,
 197                                         (errcode(ERRCODE_OUT_OF_MEMORY),
 198                                          errmsg("out of memory")));
 199                 sprintf(new, "%s/%s", buf, dir);
 200                 free(buf);
 201         }
 202         else
 203         {
 204                 new = strdup(dir);
 205                 if (!new)
 206                         ereport(FATAL,
 207                                         (errcode(ERRCODE_OUT_OF_MEMORY),
 208                                          errmsg("out of memory")));
 209         }
 210
 211         /*
 212          * Strip any trailing slash.  Not strictly necessary, but avoids
 213          * generating funny-looking paths to individual files.
 214          */
 215         newlen = strlen(new);
 216         if (newlen > 1 && new[newlen - 1] == '/'
 217 #ifdef WIN32
 218                 || new[newlen - 1] == '\\'
 219 #endif
 220                 )
 221                 new[newlen - 1] = '\0';
 222
 223         if (DataDir)
 224                 free(DataDir);
 225         DataDir = new;
 226 }
 227
 228
 229 /* ----------------------------------------------------------------
 230  *      User ID things
 231  *
 232  * The authenticated user is determined at connection start and never
 233  * changes.  The session user can be changed only by SET SESSION
 234  * AUTHORIZATION.  The current user may change when "setuid" functions
 235  * are implemented.  Conceptually there is a stack, whose bottom
 236  * is the session user.  You are yourself responsible to save and
 237  * restore the current user id if you need to change it.
 238  * ----------------------------------------------------------------
 239  */
 240 static AclId AuthenticatedUserId = 0;
 241 static AclId SessionUserId = 0;
 242 static AclId CurrentUserId = 0;
 243
 244 static bool AuthenticatedUserIsSuperuser = false;
 245
 246 /*
 247  * This function is relevant for all privilege checks.
 248  */
 249 AclId
 250 GetUserId(void)
 251 {
 252         AssertState(AclIdIsValid(CurrentUserId));
 253         return CurrentUserId;
 254 }
 255
 256
 257 void
 258 SetUserId(AclId newid)
 259 {
 260         AssertArg(AclIdIsValid(newid));
 261         CurrentUserId = newid;
 262 }
 263
 264
 265 /*
 266  * This value is only relevant for informational purposes.
 267  */
 268 AclId
 269 GetSessionUserId(void)
 270 {
 271         AssertState(AclIdIsValid(SessionUserId));
 272         return SessionUserId;
 273 }
 274
 275
 276 void
 277 SetSessionUserId(AclId newid)
 278 {
 279         AssertArg(AclIdIsValid(newid));
 280         SessionUserId = newid;
 281         /* Current user defaults to session user. */
 282         if (!AclIdIsValid(CurrentUserId))
 283                 CurrentUserId = newid;
 284 }
 285
 286
 287 void
 288 InitializeSessionUserId(const char *username)
 289 {
 290         HeapTuple       userTup;
 291         Datum           datum;
 292         bool            isnull;
 293         AclId           usesysid;
 294
 295         /*
 296          * Don't do scans if we're bootstrapping, none of the system catalogs
 297          * exist yet, and they should be owned by postgres anyway.
 298          */
 299         AssertState(!IsBootstrapProcessingMode());
 300
 301         /* call only once */
 302         AssertState(!OidIsValid(AuthenticatedUserId));
 303
 304         userTup = SearchSysCache(SHADOWNAME,
 305                                                          PointerGetDatum(username),
 306                                                          0, 0, 0);
 307         if (!HeapTupleIsValid(userTup))
 308                 ereport(FATAL,
 309                                 (errcode(ERRCODE_UNDEFINED_OBJECT),
 310                                  errmsg("user \"%s\" does not exist", username)));
 311
 312         usesysid = ((Form_pg_shadow) GETSTRUCT(userTup))->usesysid;
 313
 314         AuthenticatedUserId = usesysid;
 315         AuthenticatedUserIsSuperuser = ((Form_pg_shadow) GETSTRUCT(userTup))->usesuper;
 316
 317         SetSessionUserId(usesysid); /* sets CurrentUserId too */
 318
 319         /* Record username and superuser status as GUC settings too */
 320         SetConfigOption("session_authorization", username,
 321                                         PGC_BACKEND, PGC_S_OVERRIDE);
 322         SetConfigOption("is_superuser",
 323                                         AuthenticatedUserIsSuperuser ? "on" : "off",
 324                                         PGC_INTERNAL, PGC_S_OVERRIDE);
 325
 326         /*
 327          * Set up user-specific configuration variables.  This is a good place
 328          * to do it so we don't have to read pg_shadow twice during session
 329          * startup.
 330          */
 331         datum = SysCacheGetAttr(SHADOWNAME, userTup,
 332                                                         Anum_pg_shadow_useconfig, &isnull);
 333         if (!isnull)
 334         {
 335                 ArrayType  *a = DatumGetArrayTypeP(datum);
 336
 337                 ProcessGUCArray(a, PGC_S_USER);
 338         }
 339
 340         ReleaseSysCache(userTup);
 341 }
 342
 343
 344 void
 345 InitializeSessionUserIdStandalone(void)
 346 {
 347         /* This function should only be called in a single-user backend. */
 348         AssertState(!IsUnderPostmaster);
 349
 350         /* call only once */
 351         AssertState(!OidIsValid(AuthenticatedUserId));
 352
 353         AuthenticatedUserId = BOOTSTRAP_USESYSID;
 354         AuthenticatedUserIsSuperuser = true;
 355
 356         SetSessionUserId(BOOTSTRAP_USESYSID);
 357 }
 358
 359
 360 /*
 361  * Change session auth ID while running
 362  *
 363  * Only a superuser may set auth ID to something other than himself.  Note
 364  * that in case of multiple SETs in a single session, the original userid's
 365  * superuserness is what matters.  But we set the GUC variable is_superuser
 366  * to indicate whether the *current* session userid is a superuser.
 367  */
 368 void
 369 SetSessionAuthorization(AclId userid, bool is_superuser)
 370 {
 371         /* Must have authenticated already, else can't make permission check */
 372         AssertState(AclIdIsValid(AuthenticatedUserId));
 373
 374         if (userid != AuthenticatedUserId &&
 375                 !AuthenticatedUserIsSuperuser)
 376                 ereport(ERROR,
 377                                 (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
 378                           errmsg("permission denied to set session authorization")));
 379
 380         SetSessionUserId(userid);
 381         SetUserId(userid);
 382
 383         SetConfigOption("is_superuser",
 384                                         is_superuser ? "on" : "off",
 385                                         PGC_INTERNAL, PGC_S_OVERRIDE);
 386 }
 387
 388
 389 /*
 390  * Get user name from user id
 391  */
 392 char *
 393 GetUserNameFromId(AclId userid)
 394 {
 395         HeapTuple       tuple;
 396         char       *result;
 397
 398         tuple = SearchSysCache(SHADOWSYSID,
 399                                                    ObjectIdGetDatum(userid),
 400                                                    0, 0, 0);
 401         if (!HeapTupleIsValid(tuple))
 402                 ereport(ERROR,
 403                                 (errcode(ERRCODE_UNDEFINED_OBJECT),
 404                                  errmsg("invalid user id: %d", userid)));
 405
 406         result = pstrdup(NameStr(((Form_pg_shadow) GETSTRUCT(tuple))->usename));
 407
 408         ReleaseSysCache(tuple);
 409         return result;
 410 }
 411
 412
 413
 414 /*-------------------------------------------------------------------------
 415  *                              Interlock-file support
 416  *
 417  * These routines are used to create both a data-directory lockfile
 418  * ($DATADIR/postmaster.pid) and a Unix-socket-file lockfile ($SOCKFILE.lock).
 419  * Both kinds of files contain the same info:
 420  *
 421  *              Owning process' PID
 422  *              Data directory path
 423  *
 424  * By convention, the owning process' PID is negated if it is a standalone
 425  * backend rather than a postmaster.  This is just for informational purposes.
 426  * The path is also just for informational purposes (so that a socket lockfile
 427  * can be more easily traced to the associated postmaster).
 428  *
 429  * A data-directory lockfile can optionally contain a third line, containing
 430  * the key and ID for the shared memory block used by this postmaster.
 431  *
 432  * On successful lockfile creation, a proc_exit callback to remove the
 433  * lockfile is automatically created.
 434  *-------------------------------------------------------------------------
 435  */
 436
 437 /*
 438  * proc_exit callback to remove a lockfile.
 439  */
 440 static void
 441 UnlinkLockFile(int status, Datum filename)
 442 {
 443         char       *fname = (char *) DatumGetPointer(filename);
 444
 445         if (fname != NULL)
 446         {
 447                 if (unlink(fname) != 0)
 448                 {
 449                         /* Should we complain if the unlink fails? */
 450                 }
 451                 free(fname);
 452         }
 453 }
 454
 455 /*
 456  * Create a lockfile.
 457  *
 458  * filename is the name of the lockfile to create.
 459  * amPostmaster is used to determine how to encode the output PID.
 460  * isDDLock and refName are used to determine what error message to produce.
 461  */
 462 static void
 463 CreateLockFile(const char *filename, bool amPostmaster,
 464                            bool isDDLock, const char *refName)
 465 {
 466         int                     fd;
 467         char            buffer[MAXPGPATH + 100];
 468         int                     ntries;
 469         int                     len;
 470         int                     encoded_pid;
 471         pid_t           other_pid;
 472         pid_t           my_pid = getpid();
 473
 474         /*
 475          * We need a loop here because of race conditions.      But don't loop
 476          * forever (for example, a non-writable $PGDATA directory might cause
 477          * a failure that won't go away).  100 tries seems like plenty.
 478          */
 479         for (ntries = 0;; ntries++)
 480         {
 481                 /*
 482                  * Try to create the lock file --- O_EXCL makes this atomic.
 483                  */
 484                 fd = open(filename, O_RDWR | O_CREAT | O_EXCL, 0600);
 485                 if (fd >= 0)
 486                         break;                          /* Success; exit the retry loop */
 487
 488                 /*
 489                  * Couldn't create the pid file. Probably it already exists.
 490                  */
 491                 if ((errno != EEXIST && errno != EACCES) || ntries > 100)
 492                         ereport(FATAL,
 493                                         (errcode_for_file_access(),
 494                                          errmsg("could not create lock file \"%s\": %m",
 495                                                         filename)));
 496
 497                 /*
 498                  * Read the file to get the old owner's PID.  Note race condition
 499                  * here: file might have been deleted since we tried to create it.
 500                  */
 501                 fd = open(filename, O_RDONLY, 0600);
 502                 if (fd < 0)
 503                 {
 504                         if (errno == ENOENT)
 505                                 continue;               /* race condition; try again */
 506                         ereport(FATAL,
 507                                         (errcode_for_file_access(),
 508                                          errmsg("could not open lock file \"%s\": %m",
 509                                                         filename)));
 510                 }
 511                 if ((len = read(fd, buffer, sizeof(buffer) - 1)) <= 0)
 512                         ereport(FATAL,
 513                                         (errcode_for_file_access(),
 514                                          errmsg("could not read lock file \"%s\": %m",
 515                                                         filename)));
 516                 close(fd);
 517
 518                 buffer[len] = '\0';
 519                 encoded_pid = atoi(buffer);
 520
 521                 /* if pid < 0, the pid is for postgres, not postmaster */
 522                 other_pid = (pid_t) (encoded_pid < 0 ? -encoded_pid : encoded_pid);
 523
 524                 if (other_pid <= 0)
 525                         elog(FATAL, "bogus data in lock file \"%s\"", filename);
 526
 527                 /*
 528                  * Check to see if the other process still exists
 529                  *
 530                  * Normally kill() will fail with ESRCH if the given PID doesn't
 531                  * exist.  BeOS returns EINVAL for some silly reason, however.
 532                  */
 533                 if (other_pid != my_pid)
 534                 {
 535                         if (kill(other_pid, 0) == 0 ||
 536                                 (errno != ESRCH
 537 #ifdef __BEOS__
 538                                  && errno != EINVAL
 539 #endif
 540                                  ))
 541                         {
 542                                 /* lockfile belongs to a live process */
 543                                 ereport(FATAL,
 544                                                 (errcode(ERRCODE_LOCK_FILE_EXISTS),
 545                                                  errmsg("lock file \"%s\" already exists",
 546                                                                 filename),
 547                                                  isDDLock ?
 548                                          errhint("Is another %s (pid %d) running in \"%s\"?",
 549                                                    (encoded_pid < 0 ? "postgres" : "postmaster"),
 550                                                          (int) other_pid, refName) :
 551                                                  errhint("Is another %s (pid %d) using \"%s\"?",
 552                                                    (encoded_pid < 0 ? "postgres" : "postmaster"),
 553                                                                  (int) other_pid, refName)));
 554                         }
 555                 }
 556
 557                 /*
 558                  * No, the creating process did not exist.      However, it could be
 559                  * that the postmaster crashed (or more likely was kill -9'd by a
 560                  * clueless admin) but has left orphan backends behind.  Check for
 561                  * this by looking to see if there is an associated shmem segment
 562                  * that is still in use.
 563                  */
 564                 if (isDDLock)
 565                 {
 566                         char       *ptr;
 567                         unsigned long id1,
 568                                                 id2;
 569
 570                         ptr = strchr(buffer, '\n');
 571                         if (ptr != NULL &&
 572                                 (ptr = strchr(ptr + 1, '\n')) != NULL)
 573                         {
 574                                 ptr++;
 575                                 if (sscanf(ptr, "%lu %lu", &id1, &id2) == 2)
 576                                 {
 577                                         if (PGSharedMemoryIsInUse(id1, id2))
 578                                                 ereport(FATAL,
 579                                                                 (errcode(ERRCODE_LOCK_FILE_EXISTS),
 580                                                            errmsg("pre-existing shared memory block "
 581                                                                           "(key %lu, id %lu) is still in use",
 582                                                                           id1, id2),
 583                                                            errhint("If you're sure there are no old "
 584                                                                            "backends still running, remove "
 585                                                                            "the shared memory block with "
 586                                                                            "ipcrm(1), or just delete \"%s\".",
 587                                                                            filename)));
 588                                 }
 589                         }
 590                 }
 591
 592                 /*
 593                  * Looks like nobody's home.  Unlink the file and try again to
 594                  * create it.  Need a loop because of possible race condition
 595                  * against other would-be creators.
 596                  */
 597                 if (unlink(filename) < 0)
 598                         ereport(FATAL,
 599                                         (errcode_for_file_access(),
 600                                          errmsg("could not remove old lock file \"%s\": %m",
 601                                                         filename),
 602                                          errhint("The file seems accidentally left over, but "
 603                                                   "I couldn't remove it. Please remove the file "
 604                                                          "by hand and try again.")));
 605         }
 606
 607         /*
 608          * Successfully created the file, now fill it.
 609          */
 610         snprintf(buffer, sizeof(buffer), "%d\n%s\n",
 611                          amPostmaster ? (int) my_pid : -((int) my_pid),
 612                          DataDir);
 613         errno = 0;
 614         if (write(fd, buffer, strlen(buffer)) != strlen(buffer))
 615         {
 616                 int                     save_errno = errno;
 617
 618                 close(fd);
 619                 unlink(filename);
 620                 /* if write didn't set errno, assume problem is no disk space */
 621                 errno = save_errno ? save_errno : ENOSPC;
 622                 ereport(FATAL,
 623                                 (errcode_for_file_access(),
 624                           errmsg("could not write lock file \"%s\": %m", filename)));
 625         }
 626         close(fd);
 627
 628         /*
 629          * Arrange for automatic removal of lockfile at proc_exit.
 630          */
 631         on_proc_exit(UnlinkLockFile, PointerGetDatum(strdup(filename)));
 632 }
 633
 634 void
 635 CreateDataDirLockFile(const char *datadir, bool amPostmaster)
 636 {
 637         char            lockfile[MAXPGPATH];
 638
 639         snprintf(lockfile, sizeof(lockfile), "%s/postmaster.pid", datadir);
 640         CreateLockFile(lockfile, amPostmaster, true, datadir);
 641         /* Save name of lockfile for RecordSharedMemoryInLockFile */
 642         strcpy(directoryLockFile, lockfile);
 643 }
 644
 645 void
 646 CreateSocketLockFile(const char *socketfile, bool amPostmaster)
 647 {
 648         char            lockfile[MAXPGPATH];
 649
 650         snprintf(lockfile, sizeof(lockfile), "%s.lock", socketfile);
 651         CreateLockFile(lockfile, amPostmaster, false, socketfile);
 652         /* Save name of lockfile for TouchSocketLockFile */
 653         strcpy(socketLockFile, lockfile);
 654 }
 655
 656 /*
 657  * TouchSocketLockFile -- mark socket lock file as recently accessed
 658  *
 659  * This routine should be called every so often to ensure that the lock file
 660  * has a recent mod or access date.  That saves it
 661  * from being removed by overenthusiastic /tmp-directory-cleaner daemons.
 662  * (Another reason we should never have put the socket file in /tmp...)
 663  */
 664 void
 665 TouchSocketLockFile(void)
 666 {
 667         /* Do nothing if we did not create a socket... */
 668         if (socketLockFile[0] != '\0')
 669         {
 670                 /*
 671                  * utime() is POSIX standard, utimes() is a common alternative; if
 672                  * we have neither, fall back to actually reading the file (which
 673                  * only sets the access time not mod time, but that should be
 674                  * enough in most cases).  In all paths, we ignore errors.
 675                  */
 676 #ifdef HAVE_UTIME
 677                 utime(socketLockFile, NULL);
 678 #else                                                   /* !HAVE_UTIME */
 679 #ifdef HAVE_UTIMES
 680                 utimes(socketLockFile, NULL);
 681 #else                                                   /* !HAVE_UTIMES */
 682                 int                     fd;
 683                 char            buffer[1];
 684
 685                 fd = open(socketLockFile, O_RDONLY | PG_BINARY, 0);
 686                 if (fd >= 0)
 687                 {
 688                         read(fd, buffer, sizeof(buffer));
 689                         close(fd);
 690                 }
 691 #endif   /* HAVE_UTIMES */
 692 #endif   /* HAVE_UTIME */
 693         }
 694 }
 695
 696 /*
 697  * Append information about a shared memory segment to the data directory
 698  * lock file (if we have created one).
 699  *
 700  * This may be called multiple times in the life of a postmaster, if we
 701  * delete and recreate shmem due to backend crash.      Therefore, be prepared
 702  * to overwrite existing information.  (As of 7.1, a postmaster only creates
 703  * one shm seg at a time; but for the purposes here, if we did have more than
 704  * one then any one of them would do anyway.)
 705  */
 706 void
 707 RecordSharedMemoryInLockFile(unsigned long id1, unsigned long id2)
 708 {
 709         int                     fd;
 710         int                     len;
 711         char       *ptr;
 712         char            buffer[BLCKSZ];
 713
 714         /*
 715          * Do nothing if we did not create a lockfile (probably because we are
 716          * running standalone).
 717          */
 718         if (directoryLockFile[0] == '\0')
 719                 return;
 720
 721         fd = open(directoryLockFile, O_RDWR | PG_BINARY, 0);
 722         if (fd < 0)
 723         {
 724                 ereport(LOG,
 725                                 (errcode_for_file_access(),
 726                                  errmsg("could not rewrite \"%s\": %m",
 727                                                 directoryLockFile)));
 728                 return;
 729         }
 730         len = read(fd, buffer, sizeof(buffer) - 100);
 731         if (len <= 0)
 732         {
 733                 ereport(LOG,
 734                                 (errcode_for_file_access(),
 735                                  errmsg("could not read \"%s\": %m",
 736                                                 directoryLockFile)));
 737                 close(fd);
 738                 return;
 739         }
 740         buffer[len] = '\0';
 741
 742         /*
 743          * Skip over first two lines (PID and path).
 744          */
 745         ptr = strchr(buffer, '\n');
 746         if (ptr == NULL ||
 747                 (ptr = strchr(ptr + 1, '\n')) == NULL)
 748         {
 749                 elog(LOG, "bogus data in \"%s\"", directoryLockFile);
 750                 close(fd);
 751                 return;
 752         }
 753         ptr++;
 754
 755         /*
 756          * Append key information.      Format to try to keep it the same length
 757          * always (trailing junk won't hurt, but might confuse humans).
 758          */
 759         sprintf(ptr, "%9lu %9lu\n", id1, id2);
 760
 761         /*
 762          * And rewrite the data.  Since we write in a single kernel call, this
 763          * update should appear atomic to onlookers.
 764          */
 765         len = strlen(buffer);
 766         errno = 0;
 767         if (lseek(fd, (off_t) 0, SEEK_SET) != 0 ||
 768                 (int) write(fd, buffer, len) != len)
 769         {
 770                 /* if write didn't set errno, assume problem is no disk space */
 771                 if (errno == 0)
 772                         errno = ENOSPC;
 773                 ereport(LOG,
 774                                 (errcode_for_file_access(),
 775                                  errmsg("could not write \"%s\": %m",
 776                                                 directoryLockFile)));
 777                 close(fd);
 778                 return;
 779         }
 780         close(fd);
 781 }
 782
 783
 784 /*-------------------------------------------------------------------------
 785  *                              Version checking support
 786  *-------------------------------------------------------------------------
 787  */
 788
 789 /*
 790  * Determine whether the PG_VERSION file in directory `path' indicates
 791  * a data version compatible with the version of this program.
 792  *
 793  * If compatible, return. Otherwise, ereport(FATAL).
 794  */
 795 void
 796 ValidatePgVersion(const char *path)
 797 {
 798         char            full_path[MAXPGPATH];
 799         FILE       *file;
 800         int                     ret;
 801         long            file_major,
 802                                 file_minor;
 803         long            my_major = 0,
 804                                 my_minor = 0;
 805         char       *endptr;
 806         const char *version_string = PG_VERSION;
 807
 808         my_major = strtol(version_string, &endptr, 10);
 809         if (*endptr == '.')
 810                 my_minor = strtol(endptr + 1, NULL, 10);
 811
 812         snprintf(full_path, sizeof(full_path), "%s/PG_VERSION", path);
 813
 814         file = AllocateFile(full_path, "r");
 815         if (!file)
 816         {
 817                 if (errno == ENOENT)
 818                         ereport(FATAL,
 819                                         (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 820                                          errmsg("\"%s\" is not a valid data directory",
 821                                                         path),
 822                                          errdetail("File \"%s\" is missing.", full_path)));
 823                 else
 824                         ereport(FATAL,
 825                                         (errcode_for_file_access(),
 826                                          errmsg("could not open \"%s\": %m", full_path)));
 827         }
 828
 829         ret = fscanf(file, "%ld.%ld", &file_major, &file_minor);
 830         if (ret != 2)
 831                 ereport(FATAL,
 832                                 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 833                                  errmsg("\"%s\" is not a valid data directory",
 834                                                 path),
 835                                  errdetail("File \"%s\" does not contain valid data.",
 836                                                    full_path),
 837                                  errhint("You may need to initdb.")));
 838
 839         FreeFile(file);
 840
 841         if (my_major != file_major || my_minor != file_minor)
 842                 ereport(FATAL,
 843                                 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 844                                  errmsg("database files are incompatible with server"),
 845                                  errdetail("The data directory was initialized by PostgreSQL version %ld.%ld, "
 846                                                  "which is not compatible with this version %s.",
 847                                                    file_major, file_minor, version_string)));
 848 }
 849
 850 /*-------------------------------------------------------------------------
 851  *                              Library preload support
 852  *-------------------------------------------------------------------------
 853  */
 854
 855 #if defined(__mc68000__) && defined(__ELF__)
 856 typedef int32 ((*func_ptr) ());
 857
 858 #else
 859 typedef char *((*func_ptr) ());
 860 #endif
 861
 862 /*
 863  * process any libraries that should be preloaded and
 864  * optionally pre-initialized
 865  */
 866 void
 867 process_preload_libraries(char *preload_libraries_string)
 868 {
 869         char       *rawstring;
 870         List       *elemlist;
 871         List       *l;
 872
 873         if (preload_libraries_string == NULL)
 874                 return;
 875
 876         /* Need a modifiable copy of string */
 877         rawstring = pstrdup(preload_libraries_string);
 878
 879         /* Parse string into list of identifiers */
 880         if (!SplitIdentifierString(rawstring, ',', &elemlist))
 881         {
 882                 /* syntax error in list */
 883                 pfree(rawstring);
 884                 freeList(elemlist);
 885                 ereport(LOG,
 886                                 (errcode(ERRCODE_SYNTAX_ERROR),
 887                                  errmsg("invalid list syntax for preload_libraries configuration option")));
 888                 return;
 889         }
 890
 891         foreach(l, elemlist)
 892         {
 893                 char       *tok = (char *) lfirst(l);
 894                 char       *sep = strstr(tok, ":");
 895                 char       *filename = NULL;
 896                 char       *funcname = NULL;
 897                 func_ptr        initfunc;
 898
 899                 if (sep)
 900                 {
 901                         /*
 902                          * a colon separator implies there is an initialization
 903                          * function that we need to run in addition to loading the
 904                          * library
 905                          */
 906                         size_t          filename_len = sep - tok;
 907                         size_t          funcname_len = strlen(tok) - filename_len - 1;
 908
 909                         filename = (char *) palloc(filename_len + 1);
 910                         memcpy(filename, tok, filename_len);
 911                         filename[filename_len] = '\0';
 912
 913                         funcname = (char *) palloc(funcname_len + 1);
 914                         strcpy(funcname, sep + 1);
 915                 }
 916                 else
 917                 {
 918                         /*
 919                          * no separator -- just load the library
 920                          */
 921                         filename = pstrdup(tok);
 922                         funcname = NULL;
 923                 }
 924
 925                 initfunc = (func_ptr) load_external_function(filename, funcname,
 926                                                                                                          true, NULL);
 927                 if (initfunc)
 928                         (*initfunc) ();
 929
 930                 if (funcname)
 931                         ereport(LOG,
 932                                         (errmsg("preloaded library \"%s\" with initialization function \"%s\"",
 933                                                         filename, funcname)));
 934                 else
 935                         ereport(LOG,
 936                                         (errmsg("preloaded library \"%s\"",
 937                                                         filename)));
 938
 939                 pfree(filename);
 940                 if (funcname)
 941                         pfree(funcname);
 942         }
 943
 944         pfree(rawstring);
 945         freeList(elemlist);
 946 }