/*------------------------------------------------------------------------- * * postinit.c * postgres initialization utilities * * Portions Copyright (c) 1996-2006, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION * $PostgreSQL: pgsql/src/backend/utils/init/postinit.c,v 1.171 2006/10/04 00:30:02 momjian Exp $ * * *------------------------------------------------------------------------- */ #include "postgres.h" #include #include #include "access/heapam.h" #include "access/xact.h" #include "catalog/catalog.h" #include "catalog/namespace.h" #include "catalog/pg_authid.h" #include "catalog/pg_database.h" #include "catalog/pg_tablespace.h" #include "libpq/hba.h" #include "mb/pg_wchar.h" #include "miscadmin.h" #include "postmaster/autovacuum.h" #include "postmaster/postmaster.h" #include "storage/backendid.h" #include "storage/fd.h" #include "storage/ipc.h" #include "storage/proc.h" #include "storage/procarray.h" #include "storage/sinval.h" #include "storage/smgr.h" #include "utils/acl.h" #include "utils/flatfiles.h" #include "utils/guc.h" #include "utils/portal.h" #include "utils/relcache.h" #include "utils/syscache.h" #include "pgstat.h" static bool FindMyDatabase(const char *name, Oid *db_id, Oid *db_tablespace); static void CheckMyDatabase(const char *name, bool am_superuser); static void InitCommunication(void); static void ShutdownPostgres(int code, Datum arg); static bool ThereIsAtLeastOneRole(void); /*** InitPostgres support ***/ /* * FindMyDatabase -- get the critical info needed to locate my database * * Find the named database in pg_database, return its database OID and the * OID of its default tablespace. Return TRUE if found, FALSE if not. * * Since we are not yet up and running as a backend, we cannot look directly * at pg_database (we can't obtain locks nor participate in transactions). * So to get the info we need before starting up, we must look at the "flat * file" copy of pg_database that is helpfully maintained by flatfiles.c. * This is subject to various race conditions, so after we have the * transaction infrastructure started, we have to recheck the information; * see InitPostgres. */ static bool FindMyDatabase(const char *name, Oid *db_id, Oid *db_tablespace) { bool result = false; char *filename; FILE *db_file; char thisname[NAMEDATALEN]; TransactionId dummyxid; filename = database_getflatfilename(); db_file = AllocateFile(filename, "r"); if (db_file == NULL) ereport(FATAL, (errcode_for_file_access(), errmsg("could not open file \"%s\": %m", filename))); while (read_pg_database_line(db_file, thisname, db_id, db_tablespace, &dummyxid, &dummyxid)) { if (strcmp(thisname, name) == 0) { result = true; break; } } FreeFile(db_file); pfree(filename); return result; } /* * CheckMyDatabase -- fetch information from the pg_database entry for our DB */ static void CheckMyDatabase(const char *name, bool am_superuser) { HeapTuple tup; Form_pg_database dbform; /* Fetch our real pg_database row */ tup = SearchSysCache(DATABASEOID, ObjectIdGetDatum(MyDatabaseId), 0, 0, 0); if (!HeapTupleIsValid(tup)) elog(ERROR, "cache lookup failed for database %u", MyDatabaseId); dbform = (Form_pg_database) GETSTRUCT(tup); /* This recheck is strictly paranoia */ if (strcmp(name, NameStr(dbform->datname)) != 0) ereport(FATAL, (errcode(ERRCODE_UNDEFINED_DATABASE), errmsg("database \"%s\" has disappeared from pg_database", name), errdetail("Database OID %u now seems to belong to \"%s\".", MyDatabaseId, NameStr(dbform->datname)))); /* * Check permissions to connect to the database. * * These checks are not enforced when in standalone mode, so that there is * a way to recover from disabling all access to all databases, for * example "UPDATE pg_database SET datallowconn = false;". * * We do not enforce them for the autovacuum process either. */ if (IsUnderPostmaster && !IsAutoVacuumProcess()) { /* * Check that the database is currently allowing connections. */ if (!dbform->datallowconn) ereport(FATAL, (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("database \"%s\" is not currently accepting connections", name))); /* * Check privilege to connect to the database. (The am_superuser test * is redundant, but since we have the flag, might as well check it * and save a few cycles.) */ if (!am_superuser && pg_database_aclcheck(MyDatabaseId, GetUserId(), ACL_CONNECT) != ACLCHECK_OK) ereport(FATAL, (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), errmsg("permission denied for database \"%s\"", name), errdetail("User does not have CONNECT privilege."))); /* * Check connection limit for this database. * * There is a race condition here --- we create our PGPROC before * checking for other PGPROCs. If two backends did this at about the * same time, they might both think they were over the limit, while * ideally one should succeed and one fail. Getting that to work * exactly seems more trouble than it is worth, however; instead we * just document that the connection limit is approximate. */ if (dbform->datconnlimit >= 0 && !am_superuser && CountDBBackends(MyDatabaseId) > dbform->datconnlimit) ereport(FATAL, (errcode(ERRCODE_TOO_MANY_CONNECTIONS), errmsg("too many connections for database \"%s\"", name))); } /* * OK, we're golden. Next to-do item is to save the encoding info out of * the pg_database tuple. */ SetDatabaseEncoding(dbform->encoding); /* Record it as a GUC internal option, too */ SetConfigOption("server_encoding", GetDatabaseEncodingName(), PGC_INTERNAL, PGC_S_OVERRIDE); /* If we have no other source of client_encoding, use server encoding */ SetConfigOption("client_encoding", GetDatabaseEncodingName(), PGC_BACKEND, PGC_S_DEFAULT); /* * Lastly, set up any database-specific configuration variables. */ if (IsUnderPostmaster) { Datum datum; bool isnull; datum = SysCacheGetAttr(DATABASEOID, tup, Anum_pg_database_datconfig, &isnull); if (!isnull) { ArrayType *a = DatumGetArrayTypeP(datum); ProcessGUCArray(a, PGC_S_DATABASE); } } ReleaseSysCache(tup); } /* -------------------------------- * InitCommunication * * This routine initializes stuff needed for ipc, locking, etc. * it should be called something more informative. * -------------------------------- */ static void InitCommunication(void) { /* * initialize shared memory and semaphores appropriately. */ if (!IsUnderPostmaster) /* postmaster already did this */ { /* * We're running a postgres bootstrap process or a standalone backend. * Create private "shmem" and semaphores. */ CreateSharedMemoryAndSemaphores(true, 0); } } /* * Early initialization of a backend (either standalone or under postmaster). * This happens even before InitPostgres. * * If you're wondering why this is separate from InitPostgres at all: * the critical distinction is that this stuff has to happen before we can * run XLOG-related initialization, which is done before InitPostgres --- in * fact, for cases such as checkpoint creation processes, InitPostgres may * never be done at all. */ void BaseInit(void) { /* * Attach to shared memory and semaphores, and initialize our * input/output/debugging file descriptors. */ InitCommunication(); DebugFileOpen(); /* Do local initialization of file, storage and buffer managers */ InitFileAccess(); smgrinit(); InitBufferPoolAccess(); } /* -------------------------------- * InitPostgres * Initialize POSTGRES. * * In bootstrap mode neither of the parameters are used. In autovacuum * mode, the username parameter is not used. * * The return value indicates whether the userID is a superuser. (That * can only be tested inside a transaction, so we want to do it during * the startup transaction rather than doing a separate one in postgres.c.) * * As of PostgreSQL 8.2, we expect InitProcess() was already called, so we * already have a PGPROC struct ... but it's not filled in yet. * * Note: * Be very careful with the order of calls in the InitPostgres function. * -------------------------------- */ bool InitPostgres(const char *dbname, const char *username) { bool bootstrap = IsBootstrapProcessingMode(); bool autovacuum = IsAutoVacuumProcess(); bool am_superuser; char *fullpath; /* * Set up the global variables holding database id and path. But note we * won't actually try to touch the database just yet. * * We take a shortcut in the bootstrap case, otherwise we have to look up * the db name in pg_database. */ if (bootstrap) { MyDatabaseId = TemplateDbOid; MyDatabaseTableSpace = DEFAULTTABLESPACE_OID; } else { /* * Find oid and tablespace of the database we're about to open. Since * we're not yet up and running we have to use the hackish * FindMyDatabase, which looks in the flat-file copy of pg_database. */ if (!FindMyDatabase(dbname, &MyDatabaseId, &MyDatabaseTableSpace)) ereport(FATAL, (errcode(ERRCODE_UNDEFINED_DATABASE), errmsg("database \"%s\" does not exist", dbname))); } fullpath = GetDatabasePath(MyDatabaseId, MyDatabaseTableSpace); SetDatabasePath(fullpath); /* * Finish filling in the PGPROC struct, and add it to the ProcArray. (We * need to know MyDatabaseId before we can do this, since it's entered * into the PGPROC struct.) * * Once I have done this, I am visible to other backends! */ InitProcessPhase2(); /* * Initialize my entry in the shared-invalidation manager's array of * per-backend data. * * Sets up MyBackendId, a unique backend identifier. */ MyBackendId = InvalidBackendId; InitBackendSharedInvalidationState(); if (MyBackendId > MaxBackends || MyBackendId <= 0) elog(FATAL, "bad backend id: %d", MyBackendId); /* * bufmgr needs another initialization call too */ InitBufferPoolBackend(); /* * Initialize local process's access to XLOG. In bootstrap case we may * skip this since StartupXLOG() was run instead. */ if (!bootstrap) InitXLOGAccess(); /* * Initialize the relation cache and the system catalog caches. Note that * no catalog access happens here; we only set up the hashtable structure. * We must do this before starting a transaction because transaction abort * would try to touch these hashtables. */ RelationCacheInitialize(); InitCatalogCache(); /* Initialize portal manager */ EnablePortalManager(); /* * Set up process-exit callback to do pre-shutdown cleanup. This has to * be after we've initialized all the low-level modules like the buffer * manager, because during shutdown this has to run before the low-level * modules start to close down. On the other hand, we want it in place * before we begin our first transaction --- if we fail during the * initialization transaction, as is entirely possible, we need the * AbortTransaction call to clean up. */ on_shmem_exit(ShutdownPostgres, 0); /* * Start a new transaction here before first access to db */ if (!bootstrap) StartTransactionCommand(); /* * Now that we have a transaction, we can take locks. Take a writer's * lock on the database we are trying to connect to. If there is a * concurrently running DROP DATABASE on that database, this will block us * until it finishes (and has updated the flat file copy of pg_database). * * Note that the lock is not held long, only until the end of this startup * transaction. This is OK since we are already advertising our use of * the database in the PGPROC array; anyone trying a DROP DATABASE after * this point will see us there. * * Note: use of RowExclusiveLock here is reasonable because we envision * our session as being a concurrent writer of the database. If we had a * way of declaring a session as being guaranteed-read-only, we could use * AccessShareLock for such sessions and thereby not conflict against * CREATE DATABASE. */ if (!bootstrap) LockSharedObject(DatabaseRelationId, MyDatabaseId, 0, RowExclusiveLock); /* * Recheck the flat file copy of pg_database to make sure the target * database hasn't gone away. If there was a concurrent DROP DATABASE, * this ensures we will die cleanly without creating a mess. */ if (!bootstrap) { Oid dbid2; Oid tsid2; if (!FindMyDatabase(dbname, &dbid2, &tsid2) || dbid2 != MyDatabaseId || tsid2 != MyDatabaseTableSpace) ereport(FATAL, (errcode(ERRCODE_UNDEFINED_DATABASE), errmsg("database \"%s\" does not exist", dbname), errdetail("It seems to have just been dropped or renamed."))); } /* * Now we should be able to access the database directory safely. Verify * it's there and looks reasonable. */ if (!bootstrap) { if (access(fullpath, F_OK) == -1) { if (errno == ENOENT) ereport(FATAL, (errcode(ERRCODE_UNDEFINED_DATABASE), errmsg("database \"%s\" does not exist", dbname), errdetail("The database subdirectory \"%s\" is missing.", fullpath))); else ereport(FATAL, (errcode_for_file_access(), errmsg("could not access directory \"%s\": %m", fullpath))); } ValidatePgVersion(fullpath); } /* * It's now possible to do real access to the system catalogs. * * Load relcache entries for the system catalogs. This must create at * least the minimum set of "nailed-in" cache entries. */ RelationCacheInitializePhase2(); /* * Figure out our postgres user id, and see if we are a superuser. * * In standalone mode and in the autovacuum process, we use a fixed id, * otherwise we figure it out from the authenticated user name. */ if (bootstrap || autovacuum) { InitializeSessionUserIdStandalone(); am_superuser = true; } else if (!IsUnderPostmaster) { InitializeSessionUserIdStandalone(); am_superuser = true; if (!ThereIsAtLeastOneRole()) ereport(WARNING, (errcode(ERRCODE_UNDEFINED_OBJECT), errmsg("no roles are defined in this database system"), errhint("You should immediately run CREATE USER \"%s\" CREATEUSER;.", username))); } else { /* normal multiuser case */ InitializeSessionUserId(username); am_superuser = superuser(); } /* set up ACL framework (so CheckMyDatabase can check permissions) */ initialize_acl(); /* * Read the real pg_database row for our database, check permissions and * set up database-specific GUC settings. We can't do this until all the * database-access infrastructure is up. (Also, it wants to know if the * user is a superuser, so the above stuff has to happen first.) */ if (!bootstrap) CheckMyDatabase(dbname, am_superuser); /* * Check a normal user hasn't connected to a superuser reserved slot. */ if (!am_superuser && ReservedBackends > 0 && !HaveNFreeProcs(ReservedBackends)) ereport(FATAL, (errcode(ERRCODE_TOO_MANY_CONNECTIONS), errmsg("connection limit exceeded for non-superusers"))); /* * Initialize various default states that can't be set up until we've * selected the active user and gotten the right GUC settings. */ /* set default namespace search path */ InitializeSearchPath(); /* initialize client encoding */ InitializeClientEncoding(); /* initialize statistics collection for this backend */ if (!bootstrap) pgstat_bestart(); /* close the transaction we started above */ if (!bootstrap) CommitTransactionCommand(); return am_superuser; } /* * Backend-shutdown callback. Do cleanup that we want to be sure happens * before all the supporting modules begin to nail their doors shut via * their own callbacks. * * User-level cleanup, such as temp-relation removal and UNLISTEN, happens * via separate callbacks that execute before this one. We don't combine the * callbacks because we still want this one to happen if the user-level * cleanup fails. */ static void ShutdownPostgres(int code, Datum arg) { /* Make sure we've killed any active transaction */ AbortOutOfAnyTransaction(); /* * User locks are not released by transaction end, so be sure to release * them explicitly. */ LockReleaseAll(USER_LOCKMETHOD, true); } /* * Returns true if at least one role is defined in this database cluster. */ static bool ThereIsAtLeastOneRole(void) { Relation pg_authid_rel; HeapScanDesc scan; bool result; pg_authid_rel = heap_open(AuthIdRelationId, AccessShareLock); scan = heap_beginscan(pg_authid_rel, SnapshotNow, 0, NULL); result = (heap_getnext(scan, ForwardScanDirection) != NULL); heap_endscan(scan); heap_close(pg_authid_rel, AccessShareLock); return result; }