/*------------------------------------------------------------------------- * * postinit.c * postgres initialization utilities * * Portions Copyright (c) 1996-2025, PostgreSQL Global Development Group * Portions Copyright (c) 1994, Regents of the University of California * * * IDENTIFICATION * src/backend/utils/init/postinit.c * * *------------------------------------------------------------------------- */ #include "postgres.h" #include #include #include #include "access/genam.h" #include "access/heapam.h" #include "access/htup_details.h" #include "access/session.h" #include "access/tableam.h" #include "access/xact.h" #include "access/xlog.h" #include "access/xloginsert.h" #include "catalog/namespace.h" #include "catalog/pg_authid.h" #include "catalog/pg_collation.h" #include "catalog/pg_database.h" #include "catalog/pg_db_role_setting.h" #include "catalog/pg_tablespace.h" #include "libpq/auth.h" #include "libpq/libpq-be.h" #include "mb/pg_wchar.h" #include "miscadmin.h" #include "pgstat.h" #include "postmaster/autovacuum.h" #include "postmaster/postmaster.h" #include "replication/slot.h" #include "replication/slotsync.h" #include "replication/walsender.h" #include "storage/aio_subsys.h" #include "storage/bufmgr.h" #include "storage/fd.h" #include "storage/ipc.h" #include "storage/lmgr.h" #include "storage/proc.h" #include "storage/procarray.h" #include "storage/procnumber.h" #include "storage/procsignal.h" #include "storage/sinvaladt.h" #include "storage/smgr.h" #include "storage/sync.h" #include "tcop/backend_startup.h" #include "tcop/tcopprot.h" #include "utils/acl.h" #include "utils/builtins.h" #include "utils/fmgroids.h" #include "utils/guc_hooks.h" #include "utils/injection_point.h" #include "utils/memutils.h" #include "utils/pg_locale.h" #include "utils/portal.h" #include "utils/ps_status.h" #include "utils/snapmgr.h" #include "utils/syscache.h" #include "utils/timeout.h" static HeapTuple GetDatabaseTuple(const char *dbname); static HeapTuple GetDatabaseTupleByOid(Oid dboid); static void PerformAuthentication(Port *port); static void CheckMyDatabase(const char *name, bool am_superuser, bool override_allow_connections); static void ShutdownPostgres(int code, Datum arg); static void StatementTimeoutHandler(void); static void LockTimeoutHandler(void); static void IdleInTransactionSessionTimeoutHandler(void); static void TransactionTimeoutHandler(void); static void IdleSessionTimeoutHandler(void); static void IdleStatsUpdateTimeoutHandler(void); static void ClientCheckTimeoutHandler(void); static bool ThereIsAtLeastOneRole(void); static void process_startup_options(Port *port, bool am_superuser); static void process_settings(Oid databaseid, Oid roleid); /*** InitPostgres support ***/ /* * GetDatabaseTuple -- fetch the pg_database row for a database * * This is used during backend startup when we don't yet have any access to * system catalogs in general. In the worst case, we can seqscan pg_database * using nothing but the hard-wired descriptor that relcache.c creates for * pg_database. In more typical cases, relcache.c was able to load * descriptors for both pg_database and its indexes from the shared relcache * cache file, and so we can do an indexscan. criticalSharedRelcachesBuilt * tells whether we got the cached descriptors. */ static HeapTuple GetDatabaseTuple(const char *dbname) { HeapTuple tuple; Relation relation; SysScanDesc scan; ScanKeyData key[1]; /* * form a scan key */ ScanKeyInit(&key[0], Anum_pg_database_datname, BTEqualStrategyNumber, F_NAMEEQ, CStringGetDatum(dbname)); /* * Open pg_database and fetch a tuple. Force heap scan if we haven't yet * built the critical shared relcache entries (i.e., we're starting up * without a shared relcache cache file). */ relation = table_open(DatabaseRelationId, AccessShareLock); scan = systable_beginscan(relation, DatabaseNameIndexId, criticalSharedRelcachesBuilt, NULL, 1, key); tuple = systable_getnext(scan); /* Must copy tuple before releasing buffer */ if (HeapTupleIsValid(tuple)) tuple = heap_copytuple(tuple); /* all done */ systable_endscan(scan); table_close(relation, AccessShareLock); return tuple; } /* * GetDatabaseTupleByOid -- as above, but search by database OID */ static HeapTuple GetDatabaseTupleByOid(Oid dboid) { HeapTuple tuple; Relation relation; SysScanDesc scan; ScanKeyData key[1]; /* * form a scan key */ ScanKeyInit(&key[0], Anum_pg_database_oid, BTEqualStrategyNumber, F_OIDEQ, ObjectIdGetDatum(dboid)); /* * Open pg_database and fetch a tuple. Force heap scan if we haven't yet * built the critical shared relcache entries (i.e., we're starting up * without a shared relcache cache file). */ relation = table_open(DatabaseRelationId, AccessShareLock); scan = systable_beginscan(relation, DatabaseOidIndexId, criticalSharedRelcachesBuilt, NULL, 1, key); tuple = systable_getnext(scan); /* Must copy tuple before releasing buffer */ if (HeapTupleIsValid(tuple)) tuple = heap_copytuple(tuple); /* all done */ systable_endscan(scan); table_close(relation, AccessShareLock); return tuple; } /* * PerformAuthentication -- authenticate a remote client * * returns: nothing. Will not return at all if there's any failure. */ static void PerformAuthentication(Port *port) { /* This should be set already, but let's make sure */ ClientAuthInProgress = true; /* limit visibility of log messages */ /* * In EXEC_BACKEND case, we didn't inherit the contents of pg_hba.conf * etcetera from the postmaster, and have to load them ourselves. * * FIXME: [fork/exec] Ugh. Is there a way around this overhead? */ #ifdef EXEC_BACKEND /* * load_hba() and load_ident() want to work within the PostmasterContext, * so create that if it doesn't exist (which it won't). We'll delete it * again later, in PostgresMain. */ if (PostmasterContext == NULL) PostmasterContext = AllocSetContextCreate(TopMemoryContext, "Postmaster", ALLOCSET_DEFAULT_SIZES); if (!load_hba()) { /* * It makes no sense to continue if we fail to load the HBA file, * since there is no way to connect to the database in this case. */ ereport(FATAL, /* translator: %s is a configuration file */ (errmsg("could not load %s", HbaFileName))); } if (!load_ident()) { /* * It is ok to continue if we fail to load the IDENT file, although it * means that you cannot log in using any of the authentication * methods that need a user name mapping. load_ident() already logged * the details of error to the log. */ } #endif /* Capture authentication start time for logging */ conn_timing.auth_start = GetCurrentTimestamp(); /* * Set up a timeout in case a buggy or malicious client fails to respond * during authentication. Since we're inside a transaction and might do * database access, we have to use the statement_timeout infrastructure. */ enable_timeout_after(STATEMENT_TIMEOUT, AuthenticationTimeout * 1000); /* * Now perform authentication exchange. */ set_ps_display("authentication"); ClientAuthentication(port); /* might not return, if failure */ /* * Done with authentication. Disable the timeout, and log if needed. */ disable_timeout(STATEMENT_TIMEOUT, false); /* Capture authentication end time for logging */ conn_timing.auth_end = GetCurrentTimestamp(); if (log_connections & LOG_CONNECTION_AUTHORIZATION) { StringInfoData logmsg; initStringInfo(&logmsg); if (am_walsender) appendStringInfo(&logmsg, _("replication connection authorized: user=%s"), port->user_name); else appendStringInfo(&logmsg, _("connection authorized: user=%s"), port->user_name); if (!am_walsender) appendStringInfo(&logmsg, _(" database=%s"), port->database_name); if (port->application_name != NULL) appendStringInfo(&logmsg, _(" application_name=%s"), port->application_name); #ifdef USE_SSL if (port->ssl_in_use) appendStringInfo(&logmsg, _(" SSL enabled (protocol=%s, cipher=%s, bits=%d)"), be_tls_get_version(port), be_tls_get_cipher(port), be_tls_get_cipher_bits(port)); #endif #ifdef ENABLE_GSS if (port->gss) { const char *princ = be_gssapi_get_princ(port); if (princ) appendStringInfo(&logmsg, _(" GSS (authenticated=%s, encrypted=%s, delegated_credentials=%s, principal=%s)"), be_gssapi_get_auth(port) ? _("yes") : _("no"), be_gssapi_get_enc(port) ? _("yes") : _("no"), be_gssapi_get_delegation(port) ? _("yes") : _("no"), princ); else appendStringInfo(&logmsg, _(" GSS (authenticated=%s, encrypted=%s, delegated_credentials=%s)"), be_gssapi_get_auth(port) ? _("yes") : _("no"), be_gssapi_get_enc(port) ? _("yes") : _("no"), be_gssapi_get_delegation(port) ? _("yes") : _("no")); } #endif ereport(LOG, errmsg_internal("%s", logmsg.data)); pfree(logmsg.data); } set_ps_display("startup"); ClientAuthInProgress = false; /* client_min_messages is active now */ } /* * CheckMyDatabase -- fetch information from the pg_database entry for our DB */ static void CheckMyDatabase(const char *name, bool am_superuser, bool override_allow_connections) { HeapTuple tup; Form_pg_database dbform; Datum datum; bool isnull; char *collate; char *ctype; /* Fetch our pg_database row normally, via syscache */ tup = SearchSysCache1(DATABASEOID, ObjectIdGetDatum(MyDatabaseId)); 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;". */ if (IsUnderPostmaster) { /* * Check that the database is currently allowing connections. * (Background processes can override this test and the next one by * setting override_allow_connections.) */ if (!dbform->datallowconn && !override_allow_connections) 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 && !override_allow_connections && object_aclcheck(DatabaseRelationId, 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. We enforce the limit * only for regular backends, since other process types have their own * PGPROC pools. * * 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 && AmRegularBackendProcess() && !am_superuser && CountDBConnections(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_DYNAMIC_DEFAULT); /* If we have no other source of client_encoding, use server encoding */ SetConfigOption("client_encoding", GetDatabaseEncodingName(), PGC_BACKEND, PGC_S_DYNAMIC_DEFAULT); /* assign locale variables */ datum = SysCacheGetAttrNotNull(DATABASEOID, tup, Anum_pg_database_datcollate); collate = TextDatumGetCString(datum); datum = SysCacheGetAttrNotNull(DATABASEOID, tup, Anum_pg_database_datctype); ctype = TextDatumGetCString(datum); if (pg_perm_setlocale(LC_COLLATE, collate) == NULL) ereport(FATAL, (errmsg("database locale is incompatible with operating system"), errdetail("The database was initialized with LC_COLLATE \"%s\", " " which is not recognized by setlocale().", collate), errhint("Recreate the database with another locale or install the missing locale."))); if (pg_perm_setlocale(LC_CTYPE, ctype) == NULL) ereport(FATAL, (errmsg("database locale is incompatible with operating system"), errdetail("The database was initialized with LC_CTYPE \"%s\", " " which is not recognized by setlocale().", ctype), errhint("Recreate the database with another locale or install the missing locale."))); if (strcmp(ctype, "C") == 0 || strcmp(ctype, "POSIX") == 0) database_ctype_is_c = true; init_database_collation(); /* * Check collation version. See similar code in * pg_newlocale_from_collation(). Note that here we warn instead of error * in any case, so that we don't prevent connecting. */ datum = SysCacheGetAttr(DATABASEOID, tup, Anum_pg_database_datcollversion, &isnull); if (!isnull) { char *actual_versionstr; char *collversionstr; char *locale; collversionstr = TextDatumGetCString(datum); if (dbform->datlocprovider == COLLPROVIDER_LIBC) locale = collate; else { datum = SysCacheGetAttrNotNull(DATABASEOID, tup, Anum_pg_database_datlocale); locale = TextDatumGetCString(datum); } actual_versionstr = get_collation_actual_version(dbform->datlocprovider, locale); if (!actual_versionstr) /* should not happen */ elog(WARNING, "database \"%s\" has no actual collation version, but a version was recorded", name); else if (strcmp(actual_versionstr, collversionstr) != 0) ereport(WARNING, (errmsg("database \"%s\" has a collation version mismatch", name), errdetail("The database was created using collation version %s, " "but the operating system provides version %s.", collversionstr, actual_versionstr), errhint("Rebuild all objects in this database that use the default collation and run " "ALTER DATABASE %s REFRESH COLLATION VERSION, " "or build PostgreSQL with the right library version.", quote_identifier(name)))); } ReleaseSysCache(tup); } /* * pg_split_opts -- split a string of options and append it to an argv array * * The caller is responsible for ensuring the argv array is large enough. The * maximum possible number of arguments added by this routine is * (strlen(optstr) + 1) / 2. * * Because some option values can contain spaces we allow escaping using * backslashes, with \\ representing a literal backslash. */ void pg_split_opts(char **argv, int *argcp, const char *optstr) { StringInfoData s; initStringInfo(&s); while (*optstr) { bool last_was_escape = false; resetStringInfo(&s); /* skip over leading space */ while (isspace((unsigned char) *optstr)) optstr++; if (*optstr == '\0') break; /* * Parse a single option, stopping at the first space, unless it's * escaped. */ while (*optstr) { if (isspace((unsigned char) *optstr) && !last_was_escape) break; if (!last_was_escape && *optstr == '\\') last_was_escape = true; else { last_was_escape = false; appendStringInfoChar(&s, *optstr); } optstr++; } /* now store the option in the next argv[] position */ argv[(*argcp)++] = pstrdup(s.data); } pfree(s.data); } /* * Initialize MaxBackends value from config options. * * This must be called after modules have had the chance to alter GUCs in * shared_preload_libraries and before shared memory size is determined. * * Note that in EXEC_BACKEND environment, the value is passed down from * postmaster to subprocesses via BackendParameters in SubPostmasterMain; only * postmaster itself and processes not under postmaster control should call * this. */ void InitializeMaxBackends(void) { Assert(MaxBackends == 0); /* Note that this does not include "auxiliary" processes */ MaxBackends = MaxConnections + autovacuum_worker_slots + max_worker_processes + max_wal_senders + NUM_SPECIAL_WORKER_PROCS; if (MaxBackends > MAX_BACKENDS) ereport(ERROR, (errcode(ERRCODE_INVALID_PARAMETER_VALUE), errmsg("too many server processes configured"), errdetail("\"max_connections\" (%d) plus \"autovacuum_worker_slots\" (%d) plus \"max_worker_processes\" (%d) plus \"max_wal_senders\" (%d) must be less than %d.", MaxConnections, autovacuum_worker_slots, max_worker_processes, max_wal_senders, MAX_BACKENDS - (NUM_SPECIAL_WORKER_PROCS - 1)))); } /* * Initialize the number of fast-path lock slots in PGPROC. * * This must be called after modules have had the chance to alter GUCs in * shared_preload_libraries and before shared memory size is determined. */ void InitializeFastPathLocks(void) { /* Should be initialized only once. */ Assert(FastPathLockGroupsPerBackend == 0); /* * Based on the max_locks_per_transaction GUC, as that's a good indicator * of the expected number of locks, figure out the value for * FastPathLockGroupsPerBackend. This must be a power-of-two. We cap the * value at FP_LOCK_GROUPS_PER_BACKEND_MAX and insist the value is at * least 1. * * The default max_locks_per_transaction = 64 means 4 groups by default. */ FastPathLockGroupsPerBackend = Max(Min(pg_nextpower2_32(max_locks_per_xact) / FP_LOCK_SLOTS_PER_GROUP, FP_LOCK_GROUPS_PER_BACKEND_MAX), 1); /* Validate we did get a power-of-two */ Assert(FastPathLockGroupsPerBackend == pg_nextpower2_32(FastPathLockGroupsPerBackend)); } /* * Early initialization of a backend (either standalone or under postmaster). * This happens even before InitPostgres. * * This is separate from InitPostgres because it is also called by auxiliary * processes, such as the background writer process, which may not call * InitPostgres at all. */ void BaseInit(void) { Assert(MyProc != NULL); /* * Initialize our input/output/debugging file descriptors. */ DebugFileOpen(); /* * Initialize file access. Done early so other subsystems can access * files. */ InitFileAccess(); /* * Initialize statistics reporting. This needs to happen early to ensure * that pgstat's shutdown callback runs after the shutdown callbacks of * all subsystems that can produce stats (like e.g. transaction commits * can). */ pgstat_initialize(); /* * Initialize AIO before infrastructure that might need to actually * execute AIO. */ pgaio_init_backend(); /* Do local initialization of storage and buffer managers */ InitSync(); smgrinit(); InitBufferManagerAccess(); /* * Initialize temporary file access after pgstat, so that the temporary * file shutdown hook can report temporary file statistics. */ InitTemporaryFileAccess(); /* * Initialize local buffers for WAL record construction, in case we ever * try to insert XLOG. */ InitXLogInsert(); /* Initialize lock manager's local structs */ InitLockManagerAccess(); /* * Initialize replication slots after pgstat. The exit hook might need to * drop ephemeral slots, which in turn triggers stats reporting. */ ReplicationSlotInitialize(); } /* -------------------------------- * InitPostgres * Initialize POSTGRES. * * Parameters: * in_dbname, dboid: specify database to connect to, as described below * username, useroid: specify role to connect as, as described below * flags: * - INIT_PG_LOAD_SESSION_LIBS to honor [session|local]_preload_libraries. * - INIT_PG_OVERRIDE_ALLOW_CONNS to connect despite !datallowconn. * - INIT_PG_OVERRIDE_ROLE_LOGIN to connect despite !rolcanlogin. * out_dbname: optional output parameter, see below; pass NULL if not used * * The database can be specified by name, using the in_dbname parameter, or by * OID, using the dboid parameter. Specify NULL or InvalidOid respectively * for the unused parameter. If dboid is provided, the actual database * name can be returned to the caller in out_dbname. If out_dbname isn't * NULL, it must point to a buffer of size NAMEDATALEN. * * Similarly, the role can be passed by name, using the username parameter, * or by OID using the useroid parameter. * * In bootstrap mode the database and username parameters are NULL/InvalidOid. * The autovacuum launcher process doesn't specify these parameters either, * because it only goes far enough to be able to read pg_database; it doesn't * connect to any particular database. An autovacuum worker specifies a * database but not a username; conversely, a physical walsender specifies * username but not database. * * By convention, INIT_PG_LOAD_SESSION_LIBS should be passed in "flags" in * "interactive" sessions (including standalone backends), but not in * background processes such as autovacuum. Note in particular that it * shouldn't be true in parallel worker processes; those have another * mechanism for replicating their leader's set of loaded libraries. * * We expect that InitProcess() was already called, so we already have a * PGPROC struct ... but it's not completely filled in yet. * * Note: * Be very careful with the order of calls in the InitPostgres function. * -------------------------------- */ void InitPostgres(const char *in_dbname, Oid dboid, const char *username, Oid useroid, bits32 flags, char *out_dbname) { bool bootstrap = IsBootstrapProcessingMode(); bool am_superuser; char *fullpath; char dbname[NAMEDATALEN]; int nfree = 0; elog(DEBUG3, "InitPostgres"); /* * Add my PGPROC struct to the ProcArray. * * Once I have done this, I am visible to other backends! */ InitProcessPhase2(); /* Initialize status reporting */ pgstat_beinit(); /* * And initialize an entry in the PgBackendStatus array. That way, if * LWLocks or third-party authentication should happen to hang, it is * possible to retrieve some information about what is going on. */ if (!bootstrap) { pgstat_bestart_initial(); INJECTION_POINT("init-pre-auth", NULL); } /* * Initialize my entry in the shared-invalidation manager's array of * per-backend data. */ SharedInvalBackendInit(false); ProcSignalInit(MyCancelKey, MyCancelKeyLength); /* * Also set up timeout handlers needed for backend operation. We need * these in every case except bootstrap. */ if (!bootstrap) { RegisterTimeout(DEADLOCK_TIMEOUT, CheckDeadLockAlert); RegisterTimeout(STATEMENT_TIMEOUT, StatementTimeoutHandler); RegisterTimeout(LOCK_TIMEOUT, LockTimeoutHandler); RegisterTimeout(IDLE_IN_TRANSACTION_SESSION_TIMEOUT, IdleInTransactionSessionTimeoutHandler); RegisterTimeout(TRANSACTION_TIMEOUT, TransactionTimeoutHandler); RegisterTimeout(IDLE_SESSION_TIMEOUT, IdleSessionTimeoutHandler); RegisterTimeout(CLIENT_CONNECTION_CHECK_TIMEOUT, ClientCheckTimeoutHandler); RegisterTimeout(IDLE_STATS_UPDATE_TIMEOUT, IdleStatsUpdateTimeoutHandler); } /* * If this is either a bootstrap process or a standalone backend, start up * the XLOG machinery, and register to have it closed down at exit. In * other cases, the startup process is responsible for starting up the * XLOG machinery, and the checkpointer for closing it down. */ if (!IsUnderPostmaster) { /* * We don't yet have an aux-process resource owner, but StartupXLOG * and ShutdownXLOG will need one. Hence, create said resource owner * (and register a callback to clean it up after ShutdownXLOG runs). */ CreateAuxProcessResourceOwner(); StartupXLOG(); /* Release (and warn about) any buffer pins leaked in StartupXLOG */ ReleaseAuxProcessResources(true); /* Reset CurrentResourceOwner to nothing for the moment */ CurrentResourceOwner = NULL; /* * Use before_shmem_exit() so that ShutdownXLOG() can rely on DSM * segments etc to work (which in turn is required for pgstats). */ before_shmem_exit(pgstat_before_server_shutdown, 0); before_shmem_exit(ShutdownXLOG, 0); } /* * 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(); InitPlanCache(); /* Initialize portal manager */ EnablePortalManager(); /* * Load relcache entries for the shared system catalogs. This must create * at least entries for pg_database and catalogs used for authentication. */ RelationCacheInitializePhase2(); /* * Set up process-exit callback to do pre-shutdown cleanup. This is the * one of the first before_shmem_exit callbacks we register; thus, this * will be one the last things we do before low-level modules like the * buffer manager begin to close down. We need to have this 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. */ before_shmem_exit(ShutdownPostgres, 0); /* The autovacuum launcher is done here */ if (AmAutoVacuumLauncherProcess()) { /* fill in the remainder of this entry in the PgBackendStatus array */ pgstat_bestart_final(); return; } /* * Start a new transaction here before first access to db. */ if (!bootstrap) { /* statement_timestamp must be set for timeouts to work correctly */ SetCurrentStatementStartTimestamp(); StartTransactionCommand(); /* * transaction_isolation will have been set to the default by the * above. If the default is "serializable", and we are in hot * standby, we will fail if we don't change it to something lower. * Fortunately, "read committed" is plenty good enough. */ XactIsoLevel = XACT_READ_COMMITTED; } /* * Perform client authentication if necessary, then figure out our * postgres user ID, and see if we are a superuser. * * In standalone mode, autovacuum worker processes and slot sync worker * process, we use a fixed ID, otherwise we figure it out from the * authenticated user name. */ if (bootstrap || AmAutoVacuumWorkerProcess() || AmLogicalSlotSyncWorkerProcess()) { 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\" SUPERUSER;.", username != NULL ? username : "postgres"))); } else if (AmBackgroundWorkerProcess()) { if (username == NULL && !OidIsValid(useroid)) { InitializeSessionUserIdStandalone(); am_superuser = true; } else { InitializeSessionUserId(username, useroid, (flags & INIT_PG_OVERRIDE_ROLE_LOGIN) != 0); am_superuser = superuser(); } } else { /* normal multiuser case */ Assert(MyProcPort != NULL); PerformAuthentication(MyProcPort); InitializeSessionUserId(username, useroid, false); /* ensure that auth_method is actually valid, aka authn_id is not NULL */ if (MyClientConnectionInfo.authn_id) InitializeSystemUser(MyClientConnectionInfo.authn_id, hba_authname(MyClientConnectionInfo.auth_method)); am_superuser = superuser(); } /* Report any SSL/GSS details for the session. */ if (MyProcPort != NULL) { Assert(!bootstrap); pgstat_bestart_security(); } /* * Binary upgrades only allowed super-user connections */ if (IsBinaryUpgrade && !am_superuser) { ereport(FATAL, (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), errmsg("must be superuser to connect in binary upgrade mode"))); } /* * The last few regular connection slots are reserved for superusers and * roles with privileges of pg_use_reserved_connections. We do not apply * these limits to background processes, since they all have their own * pools of PGPROC slots. * * Note: At this point, the new backend has already claimed a proc struct, * so we must check whether the number of free slots is strictly less than * the reserved connection limits. */ if (AmRegularBackendProcess() && !am_superuser && (SuperuserReservedConnections + ReservedConnections) > 0 && !HaveNFreeProcs(SuperuserReservedConnections + ReservedConnections, &nfree)) { if (nfree < SuperuserReservedConnections) ereport(FATAL, (errcode(ERRCODE_TOO_MANY_CONNECTIONS), errmsg("remaining connection slots are reserved for roles with the %s attribute", "SUPERUSER"))); if (!has_privs_of_role(GetUserId(), ROLE_PG_USE_RESERVED_CONNECTIONS)) ereport(FATAL, (errcode(ERRCODE_TOO_MANY_CONNECTIONS), errmsg("remaining connection slots are reserved for roles with privileges of the \"%s\" role", "pg_use_reserved_connections"))); } /* Check replication permissions needed for walsender processes. */ if (am_walsender) { Assert(!bootstrap); if (!has_rolreplication(GetUserId())) ereport(FATAL, (errcode(ERRCODE_INSUFFICIENT_PRIVILEGE), errmsg("permission denied to start WAL sender"), errdetail("Only roles with the %s attribute may start a WAL sender process.", "REPLICATION"))); } /* * If this is a plain walsender only supporting physical replication, we * don't want to connect to any particular database. Just finish the * backend startup by processing any options from the startup packet, and * we're done. */ if (am_walsender && !am_db_walsender) { /* process any options passed in the startup packet */ if (MyProcPort != NULL) process_startup_options(MyProcPort, am_superuser); /* Apply PostAuthDelay as soon as we've read all options */ if (PostAuthDelay > 0) pg_usleep(PostAuthDelay * 1000000L); /* initialize client encoding */ InitializeClientEncoding(); /* fill in the remainder of this entry in the PgBackendStatus array */ pgstat_bestart_final(); /* close the transaction we started above */ CommitTransactionCommand(); return; } /* * Set up the global variables holding database id and default tablespace. * 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's entry in pg_database. */ if (bootstrap) { dboid = Template1DbOid; MyDatabaseTableSpace = DEFAULTTABLESPACE_OID; } else if (in_dbname != NULL) { HeapTuple tuple; Form_pg_database dbform; tuple = GetDatabaseTuple(in_dbname); if (!HeapTupleIsValid(tuple)) ereport(FATAL, (errcode(ERRCODE_UNDEFINED_DATABASE), errmsg("database \"%s\" does not exist", in_dbname))); dbform = (Form_pg_database) GETSTRUCT(tuple); dboid = dbform->oid; } else if (!OidIsValid(dboid)) { /* * If this is a background worker not bound to any particular * database, we're done now. Everything that follows only makes sense * if we are bound to a specific database. We do need to close the * transaction we started before returning. */ if (!bootstrap) { pgstat_bestart_final(); CommitTransactionCommand(); } return; } /* * Now, 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 committed its update of * pg_database). * * Note that the lock is not held long, only until the end of this startup * transaction. This is OK since we will advertise our use of the * database in the ProcArray before dropping the lock (in fact, that's the * next thing to do). Anyone trying a DROP DATABASE after this point will * see us in the array once they have the lock. Ordering is important for * this because we don't want to advertise ourselves as being in this * database until we have the lock; otherwise we create what amounts to a * deadlock with CountOtherDBBackends(). * * 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, dboid, 0, RowExclusiveLock); /* * Recheck 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) { HeapTuple tuple; Form_pg_database datform; tuple = GetDatabaseTupleByOid(dboid); if (HeapTupleIsValid(tuple)) datform = (Form_pg_database) GETSTRUCT(tuple); if (!HeapTupleIsValid(tuple) || (in_dbname && namestrcmp(&datform->datname, in_dbname))) { if (in_dbname) ereport(FATAL, (errcode(ERRCODE_UNDEFINED_DATABASE), errmsg("database \"%s\" does not exist", in_dbname), errdetail("It seems to have just been dropped or renamed."))); else ereport(FATAL, (errcode(ERRCODE_UNDEFINED_DATABASE), errmsg("database %u does not exist", dboid))); } strlcpy(dbname, NameStr(datform->datname), sizeof(dbname)); if (database_is_invalid_form(datform)) { ereport(FATAL, errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), errmsg("cannot connect to invalid database \"%s\"", dbname), errhint("Use DROP DATABASE to drop invalid databases.")); } MyDatabaseTableSpace = datform->dattablespace; MyDatabaseHasLoginEventTriggers = datform->dathasloginevt; /* pass the database name back to the caller */ if (out_dbname) strcpy(out_dbname, dbname); } /* * Now that we rechecked, we are certain to be connected to a database and * thus can set MyDatabaseId. * * It is important that MyDatabaseId only be set once we are sure that the * target database can no longer be concurrently dropped or renamed. For * example, without this guarantee, pgstat_update_dbstats() could create * entries for databases that were just dropped in the pgstat shutdown * callback, which could confuse other code paths like the autovacuum * scheduler. */ MyDatabaseId = dboid; /* * Now we can mark our PGPROC entry with the database ID. * * We assume this is an atomic store so no lock is needed; though actually * things would work fine even if it weren't atomic. Anyone searching the * ProcArray for this database's ID should hold the database lock, so they * would not be executing concurrently with this store. A process looking * for another database's ID could in theory see a chance match if it read * a partially-updated databaseId value; but as long as all such searches * wait and retry, as in CountOtherDBBackends(), they will certainly see * the correct value on their next try. */ MyProc->databaseId = MyDatabaseId; /* * We established a catalog snapshot while reading pg_authid and/or * pg_database; but until we have set up MyDatabaseId, we won't react to * incoming sinval messages for unshared catalogs, so we won't realize it * if the snapshot has been invalidated. Assume it's no good anymore. */ InvalidateCatalogSnapshot(); /* * Now we should be able to access the database directory safely. Verify * it's there and looks reasonable. */ fullpath = GetDatabasePath(MyDatabaseId, MyDatabaseTableSpace); 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); } SetDatabasePath(fullpath); pfree(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. */ RelationCacheInitializePhase3(); /* set up ACL framework (so CheckMyDatabase can check permissions) */ initialize_acl(); /* * Re-read the 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, (flags & INIT_PG_OVERRIDE_ALLOW_CONNS) != 0); /* * Now process any command-line switches and any additional GUC variable * settings passed in the startup packet. We couldn't do this before * because we didn't know if client is a superuser. */ if (MyProcPort != NULL) process_startup_options(MyProcPort, am_superuser); /* Process pg_db_role_setting options */ process_settings(MyDatabaseId, GetSessionUserId()); /* Apply PostAuthDelay as soon as we've read all options */ if (PostAuthDelay > 0) pg_usleep(PostAuthDelay * 1000000L); /* * 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 this backend's session state. */ InitializeSession(); /* * If this is an interactive session, load any libraries that should be * preloaded at backend start. Since those are determined by GUCs, this * can't happen until GUC settings are complete, but we want it to happen * during the initial transaction in case anything that requires database * access needs to be done. */ if ((flags & INIT_PG_LOAD_SESSION_LIBS) != 0) process_session_preload_libraries(); /* fill in the remainder of this entry in the PgBackendStatus array */ if (!bootstrap) pgstat_bestart_final(); /* close the transaction we started above */ if (!bootstrap) CommitTransactionCommand(); } /* * Process any command-line switches and any additional GUC variable * settings passed in the startup packet. */ static void process_startup_options(Port *port, bool am_superuser) { GucContext gucctx; ListCell *gucopts; gucctx = am_superuser ? PGC_SU_BACKEND : PGC_BACKEND; /* * First process any command-line switches that were included in the * startup packet, if we are in a regular backend. */ if (port->cmdline_options != NULL) { /* * The maximum possible number of commandline arguments that could * come from port->cmdline_options is (strlen + 1) / 2; see * pg_split_opts(). */ char **av; int maxac; int ac; maxac = 2 + (strlen(port->cmdline_options) + 1) / 2; av = (char **) palloc(maxac * sizeof(char *)); ac = 0; av[ac++] = "postgres"; pg_split_opts(av, &ac, port->cmdline_options); av[ac] = NULL; Assert(ac < maxac); (void) process_postgres_switches(ac, av, gucctx, NULL); } /* * Process any additional GUC variable settings passed in startup packet. * These are handled exactly like command-line variables. */ gucopts = list_head(port->guc_options); while (gucopts) { char *name; char *value; name = lfirst(gucopts); gucopts = lnext(port->guc_options, gucopts); value = lfirst(gucopts); gucopts = lnext(port->guc_options, gucopts); SetConfigOption(name, value, gucctx, PGC_S_CLIENT); } } /* * Load GUC settings from pg_db_role_setting. * * We try specific settings for the database/role combination, as well as * general for this database and for this user. */ static void process_settings(Oid databaseid, Oid roleid) { Relation relsetting; Snapshot snapshot; if (!IsUnderPostmaster) return; relsetting = table_open(DbRoleSettingRelationId, AccessShareLock); /* read all the settings under the same snapshot for efficiency */ snapshot = RegisterSnapshot(GetCatalogSnapshot(DbRoleSettingRelationId)); /* Later settings are ignored if set earlier. */ ApplySetting(snapshot, databaseid, roleid, relsetting, PGC_S_DATABASE_USER); ApplySetting(snapshot, InvalidOid, roleid, relsetting, PGC_S_USER); ApplySetting(snapshot, databaseid, InvalidOid, relsetting, PGC_S_DATABASE); ApplySetting(snapshot, InvalidOid, InvalidOid, relsetting, PGC_S_GLOBAL); UnregisterSnapshot(snapshot); table_close(relsetting, AccessShareLock); } /* * 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); } /* * STATEMENT_TIMEOUT handler: trigger a query-cancel interrupt. */ static void StatementTimeoutHandler(void) { int sig = SIGINT; /* * During authentication the timeout is used to deal with * authentication_timeout - we want to quit in response to such timeouts. */ if (ClientAuthInProgress) sig = SIGTERM; #ifdef HAVE_SETSID /* try to signal whole process group */ kill(-MyProcPid, sig); #endif kill(MyProcPid, sig); } /* * LOCK_TIMEOUT handler: trigger a query-cancel interrupt. */ static void LockTimeoutHandler(void) { #ifdef HAVE_SETSID /* try to signal whole process group */ kill(-MyProcPid, SIGINT); #endif kill(MyProcPid, SIGINT); } static void TransactionTimeoutHandler(void) { TransactionTimeoutPending = true; InterruptPending = true; SetLatch(MyLatch); } static void IdleInTransactionSessionTimeoutHandler(void) { IdleInTransactionSessionTimeoutPending = true; InterruptPending = true; SetLatch(MyLatch); } static void IdleSessionTimeoutHandler(void) { IdleSessionTimeoutPending = true; InterruptPending = true; SetLatch(MyLatch); } static void IdleStatsUpdateTimeoutHandler(void) { IdleStatsUpdateTimeoutPending = true; InterruptPending = true; SetLatch(MyLatch); } static void ClientCheckTimeoutHandler(void) { CheckClientConnectionPending = true; InterruptPending = true; SetLatch(MyLatch); } /* * Returns true if at least one role is defined in this database cluster. */ static bool ThereIsAtLeastOneRole(void) { Relation pg_authid_rel; TableScanDesc scan; bool result; pg_authid_rel = table_open(AuthIdRelationId, AccessShareLock); scan = table_beginscan_catalog(pg_authid_rel, 0, NULL); result = (heap_getnext(scan, ForwardScanDirection) != NULL); table_endscan(scan); table_close(pg_authid_rel, AccessShareLock); return result; }