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) 1996-2004, PostgreSQL Global Development Group
   7  * Portions Copyright (c) 1994, Regents of the University of California
   8  *
   9  *
  10  * IDENTIFICATION
  11  *        $PostgreSQL: pgsql/src/backend/utils/init/miscinit.c,v 1.132 2004/08/29 05:06:50 momjian 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 <netinet/in.h>
  27 #include <arpa/inet.h>
  28 #ifdef HAVE_UTIME_H
  29 #include <utime.h>
  30 #endif
  31
  32 #include "catalog/catname.h"
  33 #include "catalog/pg_shadow.h"
  34 #include "libpq/libpq-be.h"
  35 #include "miscadmin.h"
  36 #include "storage/fd.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  */
 119 void
 120 SetReindexProcessing(Oid heapOid, Oid indexOid)
 121 {
 122         Assert(OidIsValid(heapOid) && OidIsValid(indexOid));
 123         /* Reindexing is not re-entrant. */
 124         if (OidIsValid(currentlyReindexedIndex))
 125                 elog(ERROR, "cannot reindex while reindexing");
 126         currentlyReindexedHeap = heapOid;
 127         currentlyReindexedIndex = indexOid;
 128 }
 129
 130 /*
 131  * ResetReindexProcessing
 132  *              Unset reindexing status.
 133  */
 134 void
 135 ResetReindexProcessing(void)
 136 {
 137         currentlyReindexedHeap = InvalidOid;
 138         currentlyReindexedIndex = InvalidOid;
 139 }
 140
 141 /* ----------------------------------------------------------------
 142  *                              database path / name support stuff
 143  * ----------------------------------------------------------------
 144  */
 145
 146 void
 147 SetDatabasePath(const char *path)
 148 {
 149         if (DatabasePath)
 150         {
 151                 free(DatabasePath);
 152                 DatabasePath = NULL;
 153         }
 154         /* use strdup since this is done before memory contexts are set up */
 155         if (path)
 156         {
 157                 DatabasePath = strdup(path);
 158                 AssertState(DatabasePath);
 159         }
 160 }
 161
 162 /*
 163  * Set data directory, but make sure it's an absolute path.  Use this,
 164  * never set DataDir directly.
 165  */
 166 void
 167 SetDataDir(const char *dir)
 168 {
 169         char       *new;
 170
 171         AssertArg(dir);
 172
 173         /* If presented path is relative, convert to absolute */
 174         if (!is_absolute_path(dir))
 175         {
 176                 char       *buf;
 177                 size_t          buflen;
 178
 179                 buflen = MAXPGPATH;
 180                 for (;;)
 181                 {
 182                         buf = malloc(buflen);
 183                         if (!buf)
 184                                 ereport(FATAL,
 185                                                 (errcode(ERRCODE_OUT_OF_MEMORY),
 186                                                  errmsg("out of memory")));
 187
 188                         if (getcwd(buf, buflen))
 189                                 break;
 190                         else if (errno == ERANGE)
 191                         {
 192                                 free(buf);
 193                                 buflen *= 2;
 194                                 continue;
 195                         }
 196                         else
 197                         {
 198                                 free(buf);
 199                                 elog(FATAL, "could not get current working directory: %m");
 200                         }
 201                 }
 202
 203                 new = malloc(strlen(buf) + 1 + strlen(dir) + 1);
 204                 if (!new)
 205                         ereport(FATAL,
 206                                         (errcode(ERRCODE_OUT_OF_MEMORY),
 207                                          errmsg("out of memory")));
 208                 sprintf(new, "%s/%s", buf, dir);
 209                 free(buf);
 210         }
 211         else
 212         {
 213                 new = strdup(dir);
 214                 if (!new)
 215                         ereport(FATAL,
 216                                         (errcode(ERRCODE_OUT_OF_MEMORY),
 217                                          errmsg("out of memory")));
 218         }
 219
 220         canonicalize_path(new);
 221
 222         if (DataDir)
 223                 free(DataDir);
 224         DataDir = new;
 225 }
 226
 227
 228 /* ----------------------------------------------------------------
 229  *      User ID things
 230  *
 231  * The authenticated user is determined at connection start and never
 232  * changes.  The session user can be changed only by SET SESSION
 233  * AUTHORIZATION.  The current user may change when "setuid" functions
 234  * are implemented.  Conceptually there is a stack, whose bottom
 235  * is the session user.  You are yourself responsible to save and
 236  * restore the current user id if you need to change it.
 237  * ----------------------------------------------------------------
 238  */
 239 static AclId AuthenticatedUserId = 0;
 240 static AclId SessionUserId = 0;
 241 static AclId CurrentUserId = 0;
 242
 243 static bool AuthenticatedUserIsSuperuser = false;
 244
 245 /*
 246  * This function is relevant for all privilege checks.
 247  */
 248 AclId
 249 GetUserId(void)
 250 {
 251         AssertState(AclIdIsValid(CurrentUserId));
 252         return CurrentUserId;
 253 }
 254
 255
 256 void
 257 SetUserId(AclId newid)
 258 {
 259         AssertArg(AclIdIsValid(newid));
 260         CurrentUserId = newid;
 261 }
 262
 263
 264 /*
 265  * This value is only relevant for informational purposes.
 266  */
 267 AclId
 268 GetSessionUserId(void)
 269 {
 270         AssertState(AclIdIsValid(SessionUserId));
 271         return SessionUserId;
 272 }
 273
 274
 275 void
 276 SetSessionUserId(AclId newid)
 277 {
 278         AssertArg(AclIdIsValid(newid));
 279         SessionUserId = newid;
 280         /* Current user defaults to session user. */
 281         if (!AclIdIsValid(CurrentUserId))
 282                 CurrentUserId = newid;
 283 }
 284
 285
 286 void
 287 InitializeSessionUserId(const char *username)
 288 {
 289         HeapTuple       userTup;
 290         Datum           datum;
 291         bool            isnull;
 292         AclId           usesysid;
 293
 294         /*
 295          * Don't do scans if we're bootstrapping, none of the system catalogs
 296          * exist yet, and they should be owned by postgres anyway.
 297          */
 298         AssertState(!IsBootstrapProcessingMode());
 299
 300         /* call only once */
 301         AssertState(!OidIsValid(AuthenticatedUserId));
 302
 303         userTup = SearchSysCache(SHADOWNAME,
 304                                                          PointerGetDatum(username),
 305                                                          0, 0, 0);
 306         if (!HeapTupleIsValid(userTup))
 307                 ereport(FATAL,
 308                                 (errcode(ERRCODE_UNDEFINED_OBJECT),
 309                                  errmsg("user \"%s\" does not exist", username)));
 310
 311         usesysid = ((Form_pg_shadow) GETSTRUCT(userTup))->usesysid;
 312
 313         AuthenticatedUserId = usesysid;
 314         AuthenticatedUserIsSuperuser = ((Form_pg_shadow) GETSTRUCT(userTup))->usesuper;
 315
 316         SetSessionUserId(usesysid); /* sets CurrentUserId too */
 317
 318         /* Record username and superuser status as GUC settings too */
 319         SetConfigOption("session_authorization", username,
 320                                         PGC_BACKEND, PGC_S_OVERRIDE);
 321         SetConfigOption("is_superuser",
 322                                         AuthenticatedUserIsSuperuser ? "on" : "off",
 323                                         PGC_INTERNAL, PGC_S_OVERRIDE);
 324
 325         /*
 326          * Set up user-specific configuration variables.  This is a good place
 327          * to do it so we don't have to read pg_shadow twice during session
 328          * startup.
 329          */
 330         datum = SysCacheGetAttr(SHADOWNAME, userTup,
 331                                                         Anum_pg_shadow_useconfig, &isnull);
 332         if (!isnull)
 333         {
 334                 ArrayType  *a = DatumGetArrayTypeP(datum);
 335
 336                 ProcessGUCArray(a, PGC_S_USER);
 337         }
 338
 339         ReleaseSysCache(userTup);
 340 }
 341
 342
 343 void
 344 InitializeSessionUserIdStandalone(void)
 345 {
 346         /* This function should only be called in a single-user backend. */
 347         AssertState(!IsUnderPostmaster);
 348
 349         /* call only once */
 350         AssertState(!OidIsValid(AuthenticatedUserId));
 351
 352         AuthenticatedUserId = BOOTSTRAP_USESYSID;
 353         AuthenticatedUserIsSuperuser = true;
 354
 355         SetSessionUserId(BOOTSTRAP_USESYSID);
 356 }
 357
 358
 359 /*
 360  * Change session auth ID while running
 361  *
 362  * Only a superuser may set auth ID to something other than himself.  Note
 363  * that in case of multiple SETs in a single session, the original userid's
 364  * superuserness is what matters.  But we set the GUC variable is_superuser
 365  * to indicate whether the *current* session userid is a superuser.
 366  */
 367 void
 368 SetSessionAuthorization(AclId userid, bool is_superuser)
 369 {
 370         /* Must have authenticated already, else can't make permission check */
 371         AssertState(AclIdIsValid(AuthenticatedUserId));
 372
 373         if (userid != AuthenticatedUserId &&
 374                 !AuthenticatedUserIsSuperuser)
 375                 ereport(ERROR,
 376                                 (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE),
 377                           errmsg("permission denied to set session authorization")));
 378
 379         SetSessionUserId(userid);
 380         SetUserId(userid);
 381
 382         SetConfigOption("is_superuser",
 383                                         is_superuser ? "on" : "off",
 384                                         PGC_INTERNAL, PGC_S_OVERRIDE);
 385 }
 386
 387
 388 /*
 389  * Get user name from user id
 390  */
 391 char *
 392 GetUserNameFromId(AclId userid)
 393 {
 394         HeapTuple       tuple;
 395         char       *result;
 396
 397         tuple = SearchSysCache(SHADOWSYSID,
 398                                                    ObjectIdGetDatum(userid),
 399                                                    0, 0, 0);
 400         if (!HeapTupleIsValid(tuple))
 401                 ereport(ERROR,
 402                                 (errcode(ERRCODE_UNDEFINED_OBJECT),
 403                                  errmsg("invalid user ID: %d", userid)));
 404
 405         result = pstrdup(NameStr(((Form_pg_shadow) GETSTRUCT(tuple))->usename));
 406
 407         ReleaseSysCache(tuple);
 408         return result;
 409 }
 410
 411
 412
 413 /*-------------------------------------------------------------------------
 414  *                              Interlock-file support
 415  *
 416  * These routines are used to create both a data-directory lockfile
 417  * ($DATADIR/postmaster.pid) and a Unix-socket-file lockfile ($SOCKFILE.lock).
 418  * Both kinds of files contain the same info:
 419  *
 420  *              Owning process' PID
 421  *              Data directory path
 422  *
 423  * By convention, the owning process' PID is negated if it is a standalone
 424  * backend rather than a postmaster.  This is just for informational purposes.
 425  * The path is also just for informational purposes (so that a socket lockfile
 426  * can be more easily traced to the associated postmaster).
 427  *
 428  * A data-directory lockfile can optionally contain a third line, containing
 429  * the key and ID for the shared memory block used by this postmaster.
 430  *
 431  * On successful lockfile creation, a proc_exit callback to remove the
 432  * lockfile is automatically created.
 433  *-------------------------------------------------------------------------
 434  */
 435
 436 /*
 437  * proc_exit callback to remove a lockfile.
 438  */
 439 static void
 440 UnlinkLockFile(int status, Datum filename)
 441 {
 442         char       *fname = (char *) DatumGetPointer(filename);
 443
 444         if (fname != NULL)
 445         {
 446                 if (unlink(fname) != 0)
 447                 {
 448                         /* Should we complain if the unlink fails? */
 449                 }
 450                 free(fname);
 451         }
 452 }
 453
 454 /*
 455  * Create a lockfile.
 456  *
 457  * filename is the name of the lockfile to create.
 458  * amPostmaster is used to determine how to encode the output PID.
 459  * isDDLock and refName are used to determine what error message to produce.
 460  */
 461 static void
 462 CreateLockFile(const char *filename, bool amPostmaster,
 463                            bool isDDLock, const char *refName)
 464 {
 465         int                     fd;
 466         char            buffer[MAXPGPATH + 100];
 467         int                     ntries;
 468         int                     len;
 469         int                     encoded_pid;
 470         pid_t           other_pid;
 471         pid_t           my_pid = getpid();
 472
 473         /*
 474          * We need a loop here because of race conditions.      But don't loop
 475          * forever (for example, a non-writable $PGDATA directory might cause
 476          * a failure that won't go away).  100 tries seems like plenty.
 477          */
 478         for (ntries = 0;; ntries++)
 479         {
 480                 /*
 481                  * Try to create the lock file --- O_EXCL makes this atomic.
 482                  */
 483                 fd = open(filename, O_RDWR | O_CREAT | O_EXCL, 0600);
 484                 if (fd >= 0)
 485                         break;                          /* Success; exit the retry loop */
 486
 487                 /*
 488                  * Couldn't create the pid file. Probably it already exists.
 489                  */
 490                 if ((errno != EEXIST && errno != EACCES) || ntries > 100)
 491                         ereport(FATAL,
 492                                         (errcode_for_file_access(),
 493                                          errmsg("could not create lock file \"%s\": %m",
 494                                                         filename)));
 495
 496                 /*
 497                  * Read the file to get the old owner's PID.  Note race condition
 498                  * here: file might have been deleted since we tried to create it.
 499                  */
 500                 fd = open(filename, O_RDONLY, 0600);
 501                 if (fd < 0)
 502                 {
 503                         if (errno == ENOENT)
 504                                 continue;               /* race condition; try again */
 505                         ereport(FATAL,
 506                                         (errcode_for_file_access(),
 507                                          errmsg("could not open lock file \"%s\": %m",
 508                                                         filename)));
 509                 }
 510                 if ((len = read(fd, buffer, sizeof(buffer) - 1)) < 0)
 511                         ereport(FATAL,
 512                                         (errcode_for_file_access(),
 513                                          errmsg("could not read lock file \"%s\": %m",
 514                                                         filename)));
 515                 close(fd);
 516
 517                 buffer[len] = '\0';
 518                 encoded_pid = atoi(buffer);
 519
 520                 /* if pid < 0, the pid is for postgres, not postmaster */
 521                 other_pid = (pid_t) (encoded_pid < 0 ? -encoded_pid : encoded_pid);
 522
 523                 if (other_pid <= 0)
 524                         elog(FATAL, "bogus data in lock file \"%s\"", filename);
 525
 526                 /*
 527                  * Check to see if the other process still exists
 528                  *
 529                  * Normally kill() will fail with ESRCH if the given PID doesn't
 530                  * exist.  BeOS returns EINVAL for some silly reason, however.
 531                  */
 532                 if (other_pid != my_pid)
 533                 {
 534                         if (kill(other_pid, 0) == 0 ||
 535                                 (errno != ESRCH
 536 #ifdef __BEOS__
 537                                  && errno != EINVAL
 538 #endif
 539                                  ))
 540                         {
 541                                 /* lockfile belongs to a live process */
 542                                 ereport(FATAL,
 543                                                 (errcode(ERRCODE_LOCK_FILE_EXISTS),
 544                                                  errmsg("lock file \"%s\" already exists",
 545                                                                 filename),
 546                                                  isDDLock ?
 547                                                  errhint("Is another %s (PID %d) running in data directory \"%s\"?",
 548                                                    (encoded_pid < 0 ? "postgres" : "postmaster"),
 549                                                                  (int) other_pid, refName) :
 550                                                  errhint("Is another %s (PID %d) using socket file \"%s\"?",
 551                                                    (encoded_pid < 0 ? "postgres" : "postmaster"),
 552                                                                  (int) other_pid, refName)));
 553                         }
 554                 }
 555
 556                 /*
 557                  * No, the creating process did not exist.      However, it could be
 558                  * that the postmaster crashed (or more likely was kill -9'd by a
 559                  * clueless admin) but has left orphan backends behind.  Check for
 560                  * this by looking to see if there is an associated shmem segment
 561                  * that is still in use.
 562                  */
 563                 if (isDDLock)
 564                 {
 565                         char       *ptr;
 566                         unsigned long id1,
 567                                                 id2;
 568
 569                         ptr = strchr(buffer, '\n');
 570                         if (ptr != NULL &&
 571                                 (ptr = strchr(ptr + 1, '\n')) != NULL)
 572                         {
 573                                 ptr++;
 574                                 if (sscanf(ptr, "%lu %lu", &id1, &id2) == 2)
 575                                 {
 576                                         if (PGSharedMemoryIsInUse(id1, id2))
 577                                                 ereport(FATAL,
 578                                                                 (errcode(ERRCODE_LOCK_FILE_EXISTS),
 579                                                            errmsg("pre-existing shared memory block "
 580                                                                           "(key %lu, ID %lu) is still in use",
 581                                                                           id1, id2),
 582                                                            errhint("If you're sure there are no old "
 583                                                                 "server processes still running, remove "
 584                                                                            "the shared memory block with "
 585                                                                            "the command \"ipcrm\", or just delete the file \"%s\".",
 586                                                                            filename)));
 587                                 }
 588                         }
 589                 }
 590
 591                 /*
 592                  * Looks like nobody's home.  Unlink the file and try again to
 593                  * create it.  Need a loop because of possible race condition
 594                  * against other would-be creators.
 595                  */
 596                 if (unlink(filename) < 0)
 597                         ereport(FATAL,
 598                                         (errcode_for_file_access(),
 599                                          errmsg("could not remove old lock file \"%s\": %m",
 600                                                         filename),
 601                                          errhint("The file seems accidentally left over, but "
 602                                            "it could not be removed. Please remove the file "
 603                                                          "by hand and try again.")));
 604         }
 605
 606         /*
 607          * Successfully created the file, now fill it.
 608          */
 609         snprintf(buffer, sizeof(buffer), "%d\n%s\n",
 610                          amPostmaster ? (int) my_pid : -((int) my_pid),
 611                          DataDir);
 612         errno = 0;
 613         if (write(fd, buffer, strlen(buffer)) != strlen(buffer))
 614         {
 615                 int                     save_errno = errno;
 616
 617                 close(fd);
 618                 unlink(filename);
 619                 /* if write didn't set errno, assume problem is no disk space */
 620                 errno = save_errno ? save_errno : ENOSPC;
 621                 ereport(FATAL,
 622                                 (errcode_for_file_access(),
 623                           errmsg("could not write lock file \"%s\": %m", filename)));
 624         }
 625         if (close(fd))
 626         {
 627                 int                     save_errno = errno;
 628
 629                 unlink(filename);
 630                 errno = save_errno;
 631                 ereport(FATAL,
 632                                 (errcode_for_file_access(),
 633                           errmsg("could not write lock file \"%s\": %m", filename)));
 634         }
 635
 636         /*
 637          * Arrange for automatic removal of lockfile at proc_exit.
 638          */
 639         on_proc_exit(UnlinkLockFile, PointerGetDatum(strdup(filename)));
 640 }
 641
 642 void
 643 CreateDataDirLockFile(const char *datadir, bool amPostmaster)
 644 {
 645         char            lockfile[MAXPGPATH];
 646
 647         snprintf(lockfile, sizeof(lockfile), "%s/postmaster.pid", datadir);
 648         CreateLockFile(lockfile, amPostmaster, true, datadir);
 649         /* Save name of lockfile for RecordSharedMemoryInLockFile */
 650         strcpy(directoryLockFile, lockfile);
 651 }
 652
 653 void
 654 CreateSocketLockFile(const char *socketfile, bool amPostmaster)
 655 {
 656         char            lockfile[MAXPGPATH];
 657
 658         snprintf(lockfile, sizeof(lockfile), "%s.lock", socketfile);
 659         CreateLockFile(lockfile, amPostmaster, false, socketfile);
 660         /* Save name of lockfile for TouchSocketLockFile */
 661         strcpy(socketLockFile, lockfile);
 662 }
 663
 664 /*
 665  * TouchSocketLockFile -- mark socket lock file as recently accessed
 666  *
 667  * This routine should be called every so often to ensure that the lock file
 668  * has a recent mod or access date.  That saves it
 669  * from being removed by overenthusiastic /tmp-directory-cleaner daemons.
 670  * (Another reason we should never have put the socket file in /tmp...)
 671  */
 672 void
 673 TouchSocketLockFile(void)
 674 {
 675         /* Do nothing if we did not create a socket... */
 676         if (socketLockFile[0] != '\0')
 677         {
 678                 /*
 679                  * utime() is POSIX standard, utimes() is a common alternative; if
 680                  * we have neither, fall back to actually reading the file (which
 681                  * only sets the access time not mod time, but that should be
 682                  * enough in most cases).  In all paths, we ignore errors.
 683                  */
 684 #ifdef HAVE_UTIME
 685                 utime(socketLockFile, NULL);
 686 #else                                                   /* !HAVE_UTIME */
 687 #ifdef HAVE_UTIMES
 688                 utimes(socketLockFile, NULL);
 689 #else                                                   /* !HAVE_UTIMES */
 690                 int                     fd;
 691                 char            buffer[1];
 692
 693                 fd = open(socketLockFile, O_RDONLY | PG_BINARY, 0);
 694                 if (fd >= 0)
 695                 {
 696                         read(fd, buffer, sizeof(buffer));
 697                         close(fd);
 698                 }
 699 #endif   /* HAVE_UTIMES */
 700 #endif   /* HAVE_UTIME */
 701         }
 702 }
 703
 704 /*
 705  * Append information about a shared memory segment to the data directory
 706  * lock file (if we have created one).
 707  *
 708  * This may be called multiple times in the life of a postmaster, if we
 709  * delete and recreate shmem due to backend crash.      Therefore, be prepared
 710  * to overwrite existing information.  (As of 7.1, a postmaster only creates
 711  * one shm seg at a time; but for the purposes here, if we did have more than
 712  * one then any one of them would do anyway.)
 713  */
 714 void
 715 RecordSharedMemoryInLockFile(unsigned long id1, unsigned long id2)
 716 {
 717         int                     fd;
 718         int                     len;
 719         char       *ptr;
 720         char            buffer[BLCKSZ];
 721
 722         /*
 723          * Do nothing if we did not create a lockfile (probably because we are
 724          * running standalone).
 725          */
 726         if (directoryLockFile[0] == '\0')
 727                 return;
 728
 729         fd = open(directoryLockFile, O_RDWR | PG_BINARY, 0);
 730         if (fd < 0)
 731         {
 732                 ereport(LOG,
 733                                 (errcode_for_file_access(),
 734                                  errmsg("could not open file \"%s\": %m",
 735                                                 directoryLockFile)));
 736                 return;
 737         }
 738         len = read(fd, buffer, sizeof(buffer) - 100);
 739         if (len < 0)
 740         {
 741                 ereport(LOG,
 742                                 (errcode_for_file_access(),
 743                                  errmsg("could not read from file \"%s\": %m",
 744                                                 directoryLockFile)));
 745                 close(fd);
 746                 return;
 747         }
 748         buffer[len] = '\0';
 749
 750         /*
 751          * Skip over first two lines (PID and path).
 752          */
 753         ptr = strchr(buffer, '\n');
 754         if (ptr == NULL ||
 755                 (ptr = strchr(ptr + 1, '\n')) == NULL)
 756         {
 757                 elog(LOG, "bogus data in \"%s\"", directoryLockFile);
 758                 close(fd);
 759                 return;
 760         }
 761         ptr++;
 762
 763         /*
 764          * Append key information.      Format to try to keep it the same length
 765          * always (trailing junk won't hurt, but might confuse humans).
 766          */
 767         sprintf(ptr, "%9lu %9lu\n", id1, id2);
 768
 769         /*
 770          * And rewrite the data.  Since we write in a single kernel call, this
 771          * update should appear atomic to onlookers.
 772          */
 773         len = strlen(buffer);
 774         errno = 0;
 775         if (lseek(fd, (off_t) 0, SEEK_SET) != 0 ||
 776                 (int) write(fd, buffer, len) != len)
 777         {
 778                 /* if write didn't set errno, assume problem is no disk space */
 779                 if (errno == 0)
 780                         errno = ENOSPC;
 781                 ereport(LOG,
 782                                 (errcode_for_file_access(),
 783                                  errmsg("could not write to file \"%s\": %m",
 784                                                 directoryLockFile)));
 785                 close(fd);
 786                 return;
 787         }
 788         if (close(fd))
 789         {
 790                 ereport(LOG,
 791                                 (errcode_for_file_access(),
 792                                  errmsg("could not write to file \"%s\": %m",
 793                                                 directoryLockFile)));
 794         }
 795 }
 796
 797
 798 /*-------------------------------------------------------------------------
 799  *                              Version checking support
 800  *-------------------------------------------------------------------------
 801  */
 802
 803 /*
 804  * Determine whether the PG_VERSION file in directory `path' indicates
 805  * a data version compatible with the version of this program.
 806  *
 807  * If compatible, return. Otherwise, ereport(FATAL).
 808  */
 809 void
 810 ValidatePgVersion(const char *path)
 811 {
 812         char            full_path[MAXPGPATH];
 813         FILE       *file;
 814         int                     ret;
 815         long            file_major,
 816                                 file_minor;
 817         long            my_major = 0,
 818                                 my_minor = 0;
 819         char       *endptr;
 820         const char *version_string = PG_VERSION;
 821
 822         my_major = strtol(version_string, &endptr, 10);
 823         if (*endptr == '.')
 824                 my_minor = strtol(endptr + 1, NULL, 10);
 825
 826         snprintf(full_path, sizeof(full_path), "%s/PG_VERSION", path);
 827
 828         file = AllocateFile(full_path, "r");
 829         if (!file)
 830         {
 831                 if (errno == ENOENT)
 832                         ereport(FATAL,
 833                                         (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 834                                          errmsg("\"%s\" is not a valid data directory",
 835                                                         path),
 836                                          errdetail("File \"%s\" is missing.", full_path)));
 837                 else
 838                         ereport(FATAL,
 839                                         (errcode_for_file_access(),
 840                                    errmsg("could not open file \"%s\": %m", full_path)));
 841         }
 842
 843         ret = fscanf(file, "%ld.%ld", &file_major, &file_minor);
 844         if (ret != 2)
 845                 ereport(FATAL,
 846                                 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 847                                  errmsg("\"%s\" is not a valid data directory",
 848                                                 path),
 849                                  errdetail("File \"%s\" does not contain valid data.",
 850                                                    full_path),
 851                                  errhint("You may need to initdb.")));
 852
 853         FreeFile(file);
 854
 855         if (my_major != file_major || my_minor != file_minor)
 856                 ereport(FATAL,
 857                                 (errcode(ERRCODE_INVALID_PARAMETER_VALUE),
 858                                  errmsg("database files are incompatible with server"),
 859                                  errdetail("The data directory was initialized by PostgreSQL version %ld.%ld, "
 860                                                  "which is not compatible with this version %s.",
 861                                                    file_major, file_minor, version_string)));
 862 }
 863
 864 /*-------------------------------------------------------------------------
 865  *                              Library preload support
 866  *-------------------------------------------------------------------------
 867  */
 868
 869 #if defined(__mc68000__) && defined(__ELF__)
 870 typedef int32 ((*func_ptr) ());
 871
 872 #else
 873 typedef char *((*func_ptr) ());
 874 #endif
 875
 876 /*
 877  * process any libraries that should be preloaded and
 878  * optionally pre-initialized
 879  */
 880 void
 881 process_preload_libraries(char *preload_libraries_string)
 882 {
 883         char       *rawstring;
 884         List       *elemlist;
 885         ListCell   *l;
 886
 887         if (preload_libraries_string == NULL)
 888                 return;
 889
 890         /* Need a modifiable copy of string */
 891         rawstring = pstrdup(preload_libraries_string);
 892
 893         /* Parse string into list of identifiers */
 894         if (!SplitIdentifierString(rawstring, ',', &elemlist))
 895         {
 896                 /* syntax error in list */
 897                 pfree(rawstring);
 898                 list_free(elemlist);
 899                 ereport(LOG,
 900                                 (errcode(ERRCODE_SYNTAX_ERROR),
 901                                  errmsg("invalid list syntax for parameter \"preload_libraries\"")));
 902                 return;
 903         }
 904
 905         foreach(l, elemlist)
 906         {
 907                 char       *tok = (char *) lfirst(l);
 908                 char       *sep = strstr(tok, ":");
 909                 char       *filename = NULL;
 910                 char       *funcname = NULL;
 911                 func_ptr        initfunc;
 912
 913                 if (sep)
 914                 {
 915                         /*
 916                          * a colon separator implies there is an initialization
 917                          * function that we need to run in addition to loading the
 918                          * library
 919                          */
 920                         size_t          filename_len = sep - tok;
 921                         size_t          funcname_len = strlen(tok) - filename_len - 1;
 922
 923                         filename = (char *) palloc(filename_len + 1);
 924                         memcpy(filename, tok, filename_len);
 925                         filename[filename_len] = '\0';
 926
 927                         funcname = (char *) palloc(funcname_len + 1);
 928                         strcpy(funcname, sep + 1);
 929                 }
 930                 else
 931                 {
 932                         /*
 933                          * no separator -- just load the library
 934                          */
 935                         filename = pstrdup(tok);
 936                         funcname = NULL;
 937                 }
 938
 939                 canonicalize_path(filename);
 940                 initfunc = (func_ptr) load_external_function(filename, funcname,
 941                                                                                                          true, NULL);
 942                 if (initfunc)
 943                         (*initfunc) ();
 944
 945                 if (funcname)
 946                         ereport(LOG,
 947                                         (errmsg("preloaded library \"%s\" with initialization function \"%s\"",
 948                                                         filename, funcname)));
 949                 else
 950                         ereport(LOG,
 951                                         (errmsg("preloaded library \"%s\"",
 952                                                         filename)));
 953
 954                 pfree(filename);
 955                 if (funcname)
 956                         pfree(funcname);
 957         }
 958
 959         pfree(rawstring);
 960         list_free(elemlist);
 961 }