1 /*------------------------------------------------------------------------- 2 * 3 * postmaster.c 4 * This program acts as a clearing house for requests to the 5 * POSTGRES system. Frontend programs send a startup message 6 * to the Postmaster and the postmaster uses the info in the 7 * message to setup a backend process. 8 * 9 * The postmaster also manages system-wide operations such as 10 * startup and shutdown. The postmaster itself doesn't do those 11 * operations, mind you --- it just forks off a subprocess to do them 12 * at the right times. It also takes care of resetting the system 13 * if a backend crashes. 14 * 15 * The postmaster process creates the shared memory and semaphore 16 * pools during startup, but as a rule does not touch them itself. 17 * In particular, it is not a member of the PGPROC array of backends 18 * and so it cannot participate in lock-manager operations. Keeping 19 * the postmaster away from shared memory operations makes it simpler 20 * and more reliable. The postmaster is almost always able to recover 21 * from crashes of individual backends by resetting shared memory; 22 * if it did much with shared memory then it would be prone to crashing 23 * along with the backends. 24 * 25 * When a request message is received, we now fork() immediately. 26 * The child process performs authentication of the request, and 27 * then becomes a backend if successful. This allows the auth code 28 * to be written in a simple single-threaded style (as opposed to the 29 * crufty "poor man's multitasking" code that used to be needed). 30 * More importantly, it ensures that blockages in non-multithreaded 31 * libraries like SSL or PAM cannot cause denial of service to other 32 * clients. 33 * 34 * 35 * Portions Copyright (c) 1996-2019, PostgreSQL Global Development Group 36 * Portions Copyright (c) 1994, Regents of the University of California 37 * 38 * 39 * IDENTIFICATION 40 * src/backend/postmaster/postmaster.c 41 * 42 * NOTES 43 * 44 * Initialization: 45 * The Postmaster sets up shared memory data structures 46 * for the backends. 47 * 48 * Synchronization: 49 * The Postmaster shares memory with the backends but should avoid 50 * touching shared memory, so as not to become stuck if a crashing 51 * backend screws up locks or shared memory. Likewise, the Postmaster 52 * should never block on messages from frontend clients. 53 * 54 * Garbage Collection: 55 * The Postmaster cleans up after backends if they have an emergency 56 * exit and/or core dump. 57 * 58 * Error Reporting: 59 * Use write_stderr() only for reporting "interactive" errors 60 * (essentially, bogus arguments on the command line). Once the 61 * postmaster is launched, use ereport(). 62 * 63 *------------------------------------------------------------------------- 64 */ 65 66 #include "postgres.h" 67 68 #include <unistd.h> 69 #include <signal.h> 70 #include <time.h> 71 #include <sys/wait.h> 72 #include <ctype.h> 73 #include <sys/stat.h> 74 #include <sys/socket.h> 75 #include <fcntl.h> 76 #include <sys/param.h> 77 #include <netdb.h> 78 #include <limits.h> 79 80 #ifdef HAVE_SYS_SELECT_H 81 #include <sys/select.h> 82 #endif 83 84 #ifdef USE_BONJOUR 85 #include <dns_sd.h> 86 #endif 87 88 #ifdef USE_SYSTEMD 89 #include <systemd/sd-daemon.h> 90 #endif 91 92 #ifdef HAVE_PTHREAD_IS_THREADED_NP 93 #include <pthread.h> 94 #endif 95 96 #include "access/transam.h" 97 #include "access/xlog.h" 98 #include "bootstrap/bootstrap.h" 99 #include "catalog/pg_control.h" 100 #include "common/file_perm.h" 101 #include "common/ip.h" 102 #include "common/string.h" 103 #include "lib/ilist.h" 104 #include "libpq/auth.h" 105 #include "libpq/libpq.h" 106 #include "libpq/pqformat.h" 107 #include "libpq/pqsignal.h" 108 #include "miscadmin.h" 109 #include "pg_getopt.h" 110 #include "pgstat.h" 111 #include "port/pg_bswap.h" 112 #include "postmaster/autovacuum.h" 113 #include "postmaster/bgworker_internals.h" 114 #include "postmaster/fork_process.h" 115 #include "postmaster/pgarch.h" 116 #include "postmaster/postmaster.h" 117 #include "postmaster/syslogger.h" 118 #include "replication/logicallauncher.h" 119 #include "replication/walsender.h" 120 #include "storage/fd.h" 121 #include "storage/ipc.h" 122 #include "storage/pg_shmem.h" 123 #include "storage/pmsignal.h" 124 #include "storage/proc.h" 125 #include "tcop/tcopprot.h" 126 #include "utils/builtins.h" 127 #include "utils/datetime.h" 128 #include "utils/memutils.h" 129 #include "utils/pidfile.h" 130 #include "utils/ps_status.h" 131 #include "utils/timeout.h" 132 #include "utils/timestamp.h" 133 #include "utils/varlena.h" 134 135 #ifdef EXEC_BACKEND 136 #include "storage/spin.h" 137 #endif 138 139 140 /* 141 * Possible types of a backend. Beyond being the possible bkend_type values in 142 * struct bkend, these are OR-able request flag bits for SignalSomeChildren() 143 * and CountChildren(). 144 */ 145 #define BACKEND_TYPE_NORMAL 0x0001 /* normal backend */ 146 #define BACKEND_TYPE_AUTOVAC 0x0002 /* autovacuum worker process */ 147 #define BACKEND_TYPE_WALSND 0x0004 /* walsender process */ 148 #define BACKEND_TYPE_BGWORKER 0x0008 /* bgworker process */ 149 #define BACKEND_TYPE_ALL 0x000F /* OR of all the above */ 150 151 /* 152 * List of active backends (or child processes anyway; we don't actually 153 * know whether a given child has become a backend or is still in the 154 * authorization phase). This is used mainly to keep track of how many 155 * children we have and send them appropriate signals when necessary. 156 * 157 * "Special" children such as the startup, bgwriter and autovacuum launcher 158 * tasks are not in this list. Autovacuum worker and walsender are in it. 159 * Also, "dead_end" children are in it: these are children launched just for 160 * the purpose of sending a friendly rejection message to a would-be client. 161 * We must track them because they are attached to shared memory, but we know 162 * they will never become live backends. dead_end children are not assigned a 163 * PMChildSlot. 164 * 165 * Background workers are in this list, too. 166 */ 167 typedef struct bkend 168 { 169 pid_t pid; /* process id of backend */ 170 int32 cancel_key; /* cancel key for cancels for this backend */ 171 int child_slot; /* PMChildSlot for this backend, if any */ 172 173 /* 174 * Flavor of backend or auxiliary process. Note that BACKEND_TYPE_WALSND 175 * backends initially announce themselves as BACKEND_TYPE_NORMAL, so if 176 * bkend_type is normal, you should check for a recent transition. 177 */ 178 int bkend_type; 179 bool dead_end; /* is it going to send an error and quit? */ 180 bool bgworker_notify; /* gets bgworker start/stop notifications */ 181 dlist_node elem; /* list link in BackendList */ 182 } Backend; 183 184 static dlist_head BackendList = DLIST_STATIC_INIT(BackendList); 185 186 #ifdef EXEC_BACKEND 187 static Backend *ShmemBackendArray; 188 #endif 189 190 BackgroundWorker *MyBgworkerEntry = NULL; 191 192 193 194 /* The socket number we are listening for connections on */ 195 int PostPortNumber; 196 197 /* The directory names for Unix socket(s) */ 198 char *Unix_socket_directories; 199 200 /* The TCP listen address(es) */ 201 char *ListenAddresses; 202 203 /* 204 * ReservedBackends is the number of backends reserved for superuser use. 205 * This number is taken out of the pool size given by MaxConnections so 206 * number of backend slots available to non-superusers is 207 * (MaxConnections - ReservedBackends). Note what this really means is 208 * "if there are <= ReservedBackends connections available, only superusers 209 * can make new connections" --- pre-existing superuser connections don't 210 * count against the limit. 211 */ 212 int ReservedBackends; 213 214 /* The socket(s) we're listening to. */ 215 #define MAXLISTEN 64 216 static pgsocket ListenSocket[MAXLISTEN]; 217 218 /* 219 * Set by the -o option 220 */ 221 static char ExtraOptions[MAXPGPATH]; 222 223 /* 224 * These globals control the behavior of the postmaster in case some 225 * backend dumps core. Normally, it kills all peers of the dead backend 226 * and reinitializes shared memory. By specifying -s or -n, we can have 227 * the postmaster stop (rather than kill) peers and not reinitialize 228 * shared data structures. (Reinit is currently dead code, though.) 229 */ 230 static bool Reinit = true; 231 static int SendStop = false; 232 233 /* still more option variables */ 234 bool EnableSSL = false; 235 236 int PreAuthDelay = 0; 237 int AuthenticationTimeout = 60; 238 239 bool log_hostname; /* for ps display and logging */ 240 bool Log_connections = false; 241 bool Db_user_namespace = false; 242 243 bool enable_bonjour = false; 244 char *bonjour_name; 245 bool restart_after_crash = true; 246 247 /* PIDs of special child processes; 0 when not running */ 248 static pid_t StartupPID = 0, 249 BgWriterPID = 0, 250 CheckpointerPID = 0, 251 WalWriterPID = 0, 252 WalReceiverPID = 0, 253 AutoVacPID = 0, 254 PgArchPID = 0, 255 PgStatPID = 0, 256 SysLoggerPID = 0; 257 258 /* Startup process's status */ 259 typedef enum 260 { 261 STARTUP_NOT_RUNNING, 262 STARTUP_RUNNING, 263 STARTUP_SIGNALED, /* we sent it a SIGQUIT or SIGKILL */ 264 STARTUP_CRASHED 265 } StartupStatusEnum; 266 267 static StartupStatusEnum StartupStatus = STARTUP_NOT_RUNNING; 268 269 /* Startup/shutdown state */ 270 #define NoShutdown 0 271 #define SmartShutdown 1 272 #define FastShutdown 2 273 #define ImmediateShutdown 3 274 275 static int Shutdown = NoShutdown; 276 277 static bool FatalError = false; /* T if recovering from backend crash */ 278 279 /* 280 * We use a simple state machine to control startup, shutdown, and 281 * crash recovery (which is rather like shutdown followed by startup). 282 * 283 * After doing all the postmaster initialization work, we enter PM_STARTUP 284 * state and the startup process is launched. The startup process begins by 285 * reading the control file and other preliminary initialization steps. 286 * In a normal startup, or after crash recovery, the startup process exits 287 * with exit code 0 and we switch to PM_RUN state. However, archive recovery 288 * is handled specially since it takes much longer and we would like to support 289 * hot standby during archive recovery. 290 * 291 * When the startup process is ready to start archive recovery, it signals the 292 * postmaster, and we switch to PM_RECOVERY state. The background writer and 293 * checkpointer are launched, while the startup process continues applying WAL. 294 * If Hot Standby is enabled, then, after reaching a consistent point in WAL 295 * redo, startup process signals us again, and we switch to PM_HOT_STANDBY 296 * state and begin accepting connections to perform read-only queries. When 297 * archive recovery is finished, the startup process exits with exit code 0 298 * and we switch to PM_RUN state. 299 * 300 * Normal child backends can only be launched when we are in PM_RUN or 301 * PM_HOT_STANDBY state. (connsAllowed can also restrict launching.) 302 * In other states we handle connection requests by launching "dead_end" 303 * child processes, which will simply send the client an error message and 304 * quit. (We track these in the BackendList so that we can know when they 305 * are all gone; this is important because they're still connected to shared 306 * memory, and would interfere with an attempt to destroy the shmem segment, 307 * possibly leading to SHMALL failure when we try to make a new one.) 308 * In PM_WAIT_DEAD_END state we are waiting for all the dead_end children 309 * to drain out of the system, and therefore stop accepting connection 310 * requests at all until the last existing child has quit (which hopefully 311 * will not be very long). 312 * 313 * Notice that this state variable does not distinguish *why* we entered 314 * states later than PM_RUN --- Shutdown and FatalError must be consulted 315 * to find that out. FatalError is never true in PM_RECOVERY, PM_HOT_STANDBY, 316 * or PM_RUN states, nor in PM_SHUTDOWN states (because we don't enter those 317 * states when trying to recover from a crash). It can be true in PM_STARTUP 318 * state, because we don't clear it until we've successfully started WAL redo. 319 */ 320 typedef enum 321 { 322 PM_INIT, /* postmaster starting */ 323 PM_STARTUP, /* waiting for startup subprocess */ 324 PM_RECOVERY, /* in archive recovery mode */ 325 PM_HOT_STANDBY, /* in hot standby mode */ 326 PM_RUN, /* normal "database is alive" state */ 327 PM_STOP_BACKENDS, /* need to stop remaining backends */ 328 PM_WAIT_BACKENDS, /* waiting for live backends to exit */ 329 PM_SHUTDOWN, /* waiting for checkpointer to do shutdown 330 * ckpt */ 331 PM_SHUTDOWN_2, /* waiting for archiver and walsenders to 332 * finish */ 333 PM_WAIT_DEAD_END, /* waiting for dead_end children to exit */ 334 PM_NO_CHILDREN /* all important children have exited */ 335 } PMState; 336 337 static PMState pmState = PM_INIT; 338 339 /* 340 * While performing a "smart shutdown", we restrict new connections but stay 341 * in PM_RUN or PM_HOT_STANDBY state until all the client backends are gone. 342 * connsAllowed is a sub-state indicator showing the active restriction. 343 * It is of no interest unless pmState is PM_RUN or PM_HOT_STANDBY. 344 */ 345 typedef enum 346 { 347 ALLOW_ALL_CONNS, /* normal not-shutting-down state */ 348 ALLOW_SUPERUSER_CONNS, /* only superusers can connect */ 349 ALLOW_NO_CONNS /* no new connections allowed, period */ 350 } ConnsAllowedState; 351 352 static ConnsAllowedState connsAllowed = ALLOW_ALL_CONNS; 353 354 /* Start time of SIGKILL timeout during immediate shutdown or child crash */ 355 /* Zero means timeout is not running */ 356 static time_t AbortStartTime = 0; 357 358 /* Length of said timeout */ 359 #define SIGKILL_CHILDREN_AFTER_SECS 5 360 361 static bool ReachedNormalRunning = false; /* T if we've reached PM_RUN */ 362 363 bool ClientAuthInProgress = false; /* T during new-client 364 * authentication */ 365 366 bool redirection_done = false; /* stderr redirected for syslogger? */ 367 368 /* received START_AUTOVAC_LAUNCHER signal */ 369 static volatile sig_atomic_t start_autovac_launcher = false; 370 371 /* the launcher needs to be signalled to communicate some condition */ 372 static volatile bool avlauncher_needs_signal = false; 373 374 /* received START_WALRECEIVER signal */ 375 static volatile sig_atomic_t WalReceiverRequested = false; 376 377 /* set when there's a worker that needs to be started up */ 378 static volatile bool StartWorkerNeeded = true; 379 static volatile bool HaveCrashedWorker = false; 380 381 #ifdef USE_SSL 382 /* Set when and if SSL has been initialized properly */ 383 static bool LoadedSSL = false; 384 #endif 385 386 #ifdef USE_BONJOUR 387 static DNSServiceRef bonjour_sdref = NULL; 388 #endif 389 390 /* 391 * postmaster.c - function prototypes 392 */ 393 static void CloseServerPorts(int status, Datum arg); 394 static void unlink_external_pid_file(int status, Datum arg); 395 static void getInstallationPaths(const char *argv0); 396 static void checkControlFile(void); 397 static Port *ConnCreate(int serverFd); 398 static void ConnFree(Port *port); 399 static void reset_shared(int port); 400 static void SIGHUP_handler(SIGNAL_ARGS); 401 static void pmdie(SIGNAL_ARGS); 402 static void reaper(SIGNAL_ARGS); 403 static void sigusr1_handler(SIGNAL_ARGS); 404 static void process_startup_packet_die(SIGNAL_ARGS); 405 static void process_startup_packet_quickdie(SIGNAL_ARGS); 406 static void dummy_handler(SIGNAL_ARGS); 407 static void StartupPacketTimeoutHandler(void); 408 static void CleanupBackend(int pid, int exitstatus); 409 static bool CleanupBackgroundWorker(int pid, int exitstatus); 410 static void HandleChildCrash(int pid, int exitstatus, const char *procname); 411 static void LogChildExit(int lev, const char *procname, 412 int pid, int exitstatus); 413 static void PostmasterStateMachine(void); 414 static void BackendInitialize(Port *port); 415 static void BackendRun(Port *port) pg_attribute_noreturn(); 416 static void ExitPostmaster(int status) pg_attribute_noreturn(); 417 static int ServerLoop(void); 418 static int BackendStartup(Port *port); 419 static int ProcessStartupPacket(Port *port, bool ssl_done, bool gss_done); 420 static void SendNegotiateProtocolVersion(List *unrecognized_protocol_options); 421 static void processCancelRequest(Port *port, void *pkt); 422 static int initMasks(fd_set *rmask); 423 static void report_fork_failure_to_client(Port *port, int errnum); 424 static CAC_state canAcceptConnections(int backend_type); 425 static bool RandomCancelKey(int32 *cancel_key); 426 static void signal_child(pid_t pid, int signal); 427 static bool SignalSomeChildren(int signal, int targets); 428 static void TerminateChildren(int signal); 429 430 #define SignalChildren(sig) SignalSomeChildren(sig, BACKEND_TYPE_ALL) 431 432 static int CountChildren(int target); 433 static bool assign_backendlist_entry(RegisteredBgWorker *rw); 434 static void maybe_start_bgworkers(void); 435 static bool CreateOptsFile(int argc, char *argv[], char *fullprogname); 436 static pid_t StartChildProcess(AuxProcType type); 437 static void StartAutovacuumWorker(void); 438 static void MaybeStartWalReceiver(void); 439 static void InitPostmasterDeathWatchHandle(void); 440 441 /* 442 * Archiver is allowed to start up at the current postmaster state? 443 * 444 * If WAL archiving is enabled always, we are allowed to start archiver 445 * even during recovery. 446 */ 447 #define PgArchStartupAllowed() \ 448 ((XLogArchivingActive() && pmState == PM_RUN) || \ 449 (XLogArchivingAlways() && \ 450 (pmState == PM_RECOVERY || pmState == PM_HOT_STANDBY))) 451 452 #ifdef EXEC_BACKEND 453 454 #ifdef WIN32 455 #define WNOHANG 0 /* ignored, so any integer value will do */ 456 457 static pid_t waitpid(pid_t pid, int *exitstatus, int options); 458 static void WINAPI pgwin32_deadchild_callback(PVOID lpParameter, BOOLEAN TimerOrWaitFired); 459 460 static HANDLE win32ChildQueue; 461 462 typedef struct 463 { 464 HANDLE waitHandle; 465 HANDLE procHandle; 466 DWORD procId; 467 } win32_deadchild_waitinfo; 468 #endif /* WIN32 */ 469 470 static pid_t backend_forkexec(Port *port); 471 static pid_t internal_forkexec(int argc, char *argv[], Port *port); 472 473 /* Type for a socket that can be inherited to a client process */ 474 #ifdef WIN32 475 typedef struct 476 { 477 SOCKET origsocket; /* Original socket value, or PGINVALID_SOCKET 478 * if not a socket */ 479 WSAPROTOCOL_INFO wsainfo; 480 } InheritableSocket; 481 #else 482 typedef int InheritableSocket; 483 #endif 484 485 /* 486 * Structure contains all variables passed to exec:ed backends 487 */ 488 typedef struct 489 { 490 Port port; 491 InheritableSocket portsocket; 492 char DataDir[MAXPGPATH]; 493 pgsocket ListenSocket[MAXLISTEN]; 494 int32 MyCancelKey; 495 int MyPMChildSlot; 496 #ifndef WIN32 497 unsigned long UsedShmemSegID; 498 #else 499 void *ShmemProtectiveRegion; 500 HANDLE UsedShmemSegID; 501 #endif 502 void *UsedShmemSegAddr; 503 slock_t *ShmemLock; 504 VariableCache ShmemVariableCache; 505 Backend *ShmemBackendArray; 506 #ifndef HAVE_SPINLOCKS 507 PGSemaphore *SpinlockSemaArray; 508 #endif 509 int NamedLWLockTrancheRequests; 510 NamedLWLockTranche *NamedLWLockTrancheArray; 511 LWLockPadded *MainLWLockArray; 512 slock_t *ProcStructLock; 513 PROC_HDR *ProcGlobal; 514 PGPROC *AuxiliaryProcs; 515 PGPROC *PreparedXactProcs; 516 PMSignalData *PMSignalState; 517 InheritableSocket pgStatSock; 518 pid_t PostmasterPid; 519 TimestampTz PgStartTime; 520 TimestampTz PgReloadTime; 521 pg_time_t first_syslogger_file_time; 522 bool redirection_done; 523 bool IsBinaryUpgrade; 524 int max_safe_fds; 525 int MaxBackends; 526 #ifdef WIN32 527 HANDLE PostmasterHandle; 528 HANDLE initial_signal_pipe; 529 HANDLE syslogPipe[2]; 530 #else 531 int postmaster_alive_fds[2]; 532 int syslogPipe[2]; 533 #endif 534 char my_exec_path[MAXPGPATH]; 535 char pkglib_path[MAXPGPATH]; 536 char ExtraOptions[MAXPGPATH]; 537 } BackendParameters; 538 539 static void read_backend_variables(char *id, Port *port); 540 static void restore_backend_variables(BackendParameters *param, Port *port); 541 542 #ifndef WIN32 543 static bool save_backend_variables(BackendParameters *param, Port *port); 544 #else 545 static bool save_backend_variables(BackendParameters *param, Port *port, 546 HANDLE childProcess, pid_t childPid); 547 #endif 548 549 static void ShmemBackendArrayAdd(Backend *bn); 550 static void ShmemBackendArrayRemove(Backend *bn); 551 #endif /* EXEC_BACKEND */ 552 553 #define StartupDataBase() StartChildProcess(StartupProcess) 554 #define StartBackgroundWriter() StartChildProcess(BgWriterProcess) 555 #define StartCheckpointer() StartChildProcess(CheckpointerProcess) 556 #define StartWalWriter() StartChildProcess(WalWriterProcess) 557 #define StartWalReceiver() StartChildProcess(WalReceiverProcess) 558 559 /* Macros to check exit status of a child process */ 560 #define EXIT_STATUS_0(st) ((st) == 0) 561 #define EXIT_STATUS_1(st) (WIFEXITED(st) && WEXITSTATUS(st) == 1) 562 #define EXIT_STATUS_3(st) (WIFEXITED(st) && WEXITSTATUS(st) == 3) 563 564 #ifndef WIN32 565 /* 566 * File descriptors for pipe used to monitor if postmaster is alive. 567 * First is POSTMASTER_FD_WATCH, second is POSTMASTER_FD_OWN. 568 */ 569 int postmaster_alive_fds[2] = {-1, -1}; 570 #else 571 /* Process handle of postmaster used for the same purpose on Windows */ 572 HANDLE PostmasterHandle; 573 #endif 574 575 /* 576 * Postmaster main entry point 577 */ 578 void 579 PostmasterMain(int argc, char *argv[]) 580 { 581 int opt; 582 int status; 583 char *userDoption = NULL; 584 bool listen_addr_saved = false; 585 int i; 586 char *output_config_variable = NULL; 587 588 InitProcessGlobals(); 589 590 PostmasterPid = MyProcPid; 591 592 IsPostmasterEnvironment = true; 593 594 /* 595 * We should not be creating any files or directories before we check the 596 * data directory (see checkDataDir()), but just in case set the umask to 597 * the most restrictive (owner-only) permissions. 598 * 599 * checkDataDir() will reset the umask based on the data directory 600 * permissions. 601 */ 602 umask(PG_MODE_MASK_OWNER); 603 604 /* 605 * By default, palloc() requests in the postmaster will be allocated in 606 * the PostmasterContext, which is space that can be recycled by backends. 607 * Allocated data that needs to be available to backends should be 608 * allocated in TopMemoryContext. 609 */ 610 PostmasterContext = AllocSetContextCreate(TopMemoryContext, 611 "Postmaster", 612 ALLOCSET_DEFAULT_SIZES); 613 MemoryContextSwitchTo(PostmasterContext); 614 615 /* Initialize paths to installation files */ 616 getInstallationPaths(argv[0]); 617 618 /* 619 * Set up signal handlers for the postmaster process. 620 * 621 * In the postmaster, we use pqsignal_pm() rather than pqsignal() (which 622 * is used by all child processes and client processes). That has a 623 * couple of special behaviors: 624 * 625 * 1. Except on Windows, we tell sigaction() to block all signals for the 626 * duration of the signal handler. This is faster than our old approach 627 * of blocking/unblocking explicitly in the signal handler, and it should 628 * also prevent excessive stack consumption if signals arrive quickly. 629 * 630 * 2. We do not set the SA_RESTART flag. This is because signals will be 631 * blocked at all times except when ServerLoop is waiting for something to 632 * happen, and during that window, we want signals to exit the select(2) 633 * wait so that ServerLoop can respond if anything interesting happened. 634 * On some platforms, signals marked SA_RESTART would not cause the 635 * select() wait to end. 636 * 637 * Child processes will generally want SA_RESTART, so pqsignal() sets that 638 * flag. We expect children to set up their own handlers before 639 * unblocking signals. 640 * 641 * CAUTION: when changing this list, check for side-effects on the signal 642 * handling setup of child processes. See tcop/postgres.c, 643 * bootstrap/bootstrap.c, postmaster/bgwriter.c, postmaster/walwriter.c, 644 * postmaster/autovacuum.c, postmaster/pgarch.c, postmaster/pgstat.c, 645 * postmaster/syslogger.c, postmaster/bgworker.c and 646 * postmaster/checkpointer.c. 647 */ 648 pqinitmask(); 649 PG_SETMASK(&BlockSig); 650 651 pqsignal_pm(SIGHUP, SIGHUP_handler); /* reread config file and have 652 * children do same */ 653 pqsignal_pm(SIGINT, pmdie); /* send SIGTERM and shut down */ 654 pqsignal_pm(SIGQUIT, pmdie); /* send SIGQUIT and die */ 655 pqsignal_pm(SIGTERM, pmdie); /* wait for children and shut down */ 656 pqsignal_pm(SIGALRM, SIG_IGN); /* ignored */ 657 pqsignal_pm(SIGPIPE, SIG_IGN); /* ignored */ 658 pqsignal_pm(SIGUSR1, sigusr1_handler); /* message from child process */ 659 pqsignal_pm(SIGUSR2, dummy_handler); /* unused, reserve for children */ 660 pqsignal_pm(SIGCHLD, reaper); /* handle child termination */ 661 662 /* 663 * No other place in Postgres should touch SIGTTIN/SIGTTOU handling. We 664 * ignore those signals in a postmaster environment, so that there is no 665 * risk of a child process freezing up due to writing to stderr. But for 666 * a standalone backend, their default handling is reasonable. Hence, all 667 * child processes should just allow the inherited settings to stand. 668 */ 669 #ifdef SIGTTIN 670 pqsignal_pm(SIGTTIN, SIG_IGN); /* ignored */ 671 #endif 672 #ifdef SIGTTOU 673 pqsignal_pm(SIGTTOU, SIG_IGN); /* ignored */ 674 #endif 675 676 /* ignore SIGXFSZ, so that ulimit violations work like disk full */ 677 #ifdef SIGXFSZ 678 pqsignal_pm(SIGXFSZ, SIG_IGN); /* ignored */ 679 #endif 680 681 /* 682 * Options setup 683 */ 684 InitializeGUCOptions(); 685 686 opterr = 1; 687 688 /* 689 * Parse command-line options. CAUTION: keep this in sync with 690 * tcop/postgres.c (the option sets should not conflict) and with the 691 * common help() function in main/main.c. 692 */ 693 while ((opt = getopt(argc, argv, "B:bc:C:D:d:EeFf:h:ijk:lN:nOo:Pp:r:S:sTt:W:-:")) != -1) 694 { 695 switch (opt) 696 { 697 case 'B': 698 SetConfigOption("shared_buffers", optarg, PGC_POSTMASTER, PGC_S_ARGV); 699 break; 700 701 case 'b': 702 /* Undocumented flag used for binary upgrades */ 703 IsBinaryUpgrade = true; 704 break; 705 706 case 'C': 707 output_config_variable = strdup(optarg); 708 break; 709 710 case 'D': 711 userDoption = strdup(optarg); 712 break; 713 714 case 'd': 715 set_debug_options(atoi(optarg), PGC_POSTMASTER, PGC_S_ARGV); 716 break; 717 718 case 'E': 719 SetConfigOption("log_statement", "all", PGC_POSTMASTER, PGC_S_ARGV); 720 break; 721 722 case 'e': 723 SetConfigOption("datestyle", "euro", PGC_POSTMASTER, PGC_S_ARGV); 724 break; 725 726 case 'F': 727 SetConfigOption("fsync", "false", PGC_POSTMASTER, PGC_S_ARGV); 728 break; 729 730 case 'f': 731 if (!set_plan_disabling_options(optarg, PGC_POSTMASTER, PGC_S_ARGV)) 732 { 733 write_stderr("%s: invalid argument for option -f: \"%s\"\n", 734 progname, optarg); 735 ExitPostmaster(1); 736 } 737 break; 738 739 case 'h': 740 SetConfigOption("listen_addresses", optarg, PGC_POSTMASTER, PGC_S_ARGV); 741 break; 742 743 case 'i': 744 SetConfigOption("listen_addresses", "*", PGC_POSTMASTER, PGC_S_ARGV); 745 break; 746 747 case 'j': 748 /* only used by interactive backend */ 749 break; 750 751 case 'k': 752 SetConfigOption("unix_socket_directories", optarg, PGC_POSTMASTER, PGC_S_ARGV); 753 break; 754 755 case 'l': 756 SetConfigOption("ssl", "true", PGC_POSTMASTER, PGC_S_ARGV); 757 break; 758 759 case 'N': 760 SetConfigOption("max_connections", optarg, PGC_POSTMASTER, PGC_S_ARGV); 761 break; 762 763 case 'n': 764 /* Don't reinit shared mem after abnormal exit */ 765 Reinit = false; 766 break; 767 768 case 'O': 769 SetConfigOption("allow_system_table_mods", "true", PGC_POSTMASTER, PGC_S_ARGV); 770 break; 771 772 case 'o': 773 /* Other options to pass to the backend on the command line */ 774 snprintf(ExtraOptions + strlen(ExtraOptions), 775 sizeof(ExtraOptions) - strlen(ExtraOptions), 776 " %s", optarg); 777 break; 778 779 case 'P': 780 SetConfigOption("ignore_system_indexes", "true", PGC_POSTMASTER, PGC_S_ARGV); 781 break; 782 783 case 'p': 784 SetConfigOption("port", optarg, PGC_POSTMASTER, PGC_S_ARGV); 785 break; 786 787 case 'r': 788 /* only used by single-user backend */ 789 break; 790 791 case 'S': 792 SetConfigOption("work_mem", optarg, PGC_POSTMASTER, PGC_S_ARGV); 793 break; 794 795 case 's': 796 SetConfigOption("log_statement_stats", "true", PGC_POSTMASTER, PGC_S_ARGV); 797 break; 798 799 case 'T': 800 801 /* 802 * In the event that some backend dumps core, send SIGSTOP, 803 * rather than SIGQUIT, to all its peers. This lets the wily 804 * post_hacker collect core dumps from everyone. 805 */ 806 SendStop = true; 807 break; 808 809 case 't': 810 { 811 const char *tmp = get_stats_option_name(optarg); 812 813 if (tmp) 814 { 815 SetConfigOption(tmp, "true", PGC_POSTMASTER, PGC_S_ARGV); 816 } 817 else 818 { 819 write_stderr("%s: invalid argument for option -t: \"%s\"\n", 820 progname, optarg); 821 ExitPostmaster(1); 822 } 823 break; 824 } 825 826 case 'W': 827 SetConfigOption("post_auth_delay", optarg, PGC_POSTMASTER, PGC_S_ARGV); 828 break; 829 830 case 'c': 831 case '-': 832 { 833 char *name, 834 *value; 835 836 ParseLongOption(optarg, &name, &value); 837 if (!value) 838 { 839 if (opt == '-') 840 ereport(ERROR, 841 (errcode(ERRCODE_SYNTAX_ERROR), 842 errmsg("--%s requires a value", 843 optarg))); 844 else 845 ereport(ERROR, 846 (errcode(ERRCODE_SYNTAX_ERROR), 847 errmsg("-c %s requires a value", 848 optarg))); 849 } 850 851 SetConfigOption(name, value, PGC_POSTMASTER, PGC_S_ARGV); 852 free(name); 853 if (value) 854 free(value); 855 break; 856 } 857 858 default: 859 write_stderr("Try \"%s --help\" for more information.\n", 860 progname); 861 ExitPostmaster(1); 862 } 863 } 864 865 /* 866 * Postmaster accepts no non-option switch arguments. 867 */ 868 if (optind < argc) 869 { 870 write_stderr("%s: invalid argument: \"%s\"\n", 871 progname, argv[optind]); 872 write_stderr("Try \"%s --help\" for more information.\n", 873 progname); 874 ExitPostmaster(1); 875 } 876 877 /* 878 * Locate the proper configuration files and data directory, and read 879 * postgresql.conf for the first time. 880 */ 881 if (!SelectConfigFiles(userDoption, progname)) 882 ExitPostmaster(2); 883 884 if (output_config_variable != NULL) 885 { 886 /* 887 * "-C guc" was specified, so print GUC's value and exit. No extra 888 * permission check is needed because the user is reading inside the 889 * data dir. 890 */ 891 const char *config_val = GetConfigOption(output_config_variable, 892 false, false); 893 894 puts(config_val ? config_val : ""); 895 ExitPostmaster(0); 896 } 897 898 /* Verify that DataDir looks reasonable */ 899 checkDataDir(); 900 901 /* Check that pg_control exists */ 902 checkControlFile(); 903 904 /* And switch working directory into it */ 905 ChangeToDataDir(); 906 907 /* 908 * Check for invalid combinations of GUC settings. 909 */ 910 if (ReservedBackends >= MaxConnections) 911 { 912 write_stderr("%s: superuser_reserved_connections (%d) must be less than max_connections (%d)\n", 913 progname, 914 ReservedBackends, MaxConnections); 915 ExitPostmaster(1); 916 } 917 if (XLogArchiveMode > ARCHIVE_MODE_OFF && wal_level == WAL_LEVEL_MINIMAL) 918 ereport(ERROR, 919 (errmsg("WAL archival cannot be enabled when wal_level is \"minimal\""))); 920 if (max_wal_senders > 0 && wal_level == WAL_LEVEL_MINIMAL) 921 ereport(ERROR, 922 (errmsg("WAL streaming (max_wal_senders > 0) requires wal_level \"replica\" or \"logical\""))); 923 924 /* 925 * Other one-time internal sanity checks can go here, if they are fast. 926 * (Put any slow processing further down, after postmaster.pid creation.) 927 */ 928 if (!CheckDateTokenTables()) 929 { 930 write_stderr("%s: invalid datetoken tables, please fix\n", progname); 931 ExitPostmaster(1); 932 } 933 934 /* 935 * Now that we are done processing the postmaster arguments, reset 936 * getopt(3) library so that it will work correctly in subprocesses. 937 */ 938 optind = 1; 939 #ifdef HAVE_INT_OPTRESET 940 optreset = 1; /* some systems need this too */ 941 #endif 942 943 /* For debugging: display postmaster environment */ 944 { 945 extern char **environ; 946 char **p; 947 948 ereport(DEBUG3, 949 (errmsg_internal("%s: PostmasterMain: initial environment dump:", 950 progname))); 951 ereport(DEBUG3, 952 (errmsg_internal("-----------------------------------------"))); 953 for (p = environ; *p; ++p) 954 ereport(DEBUG3, 955 (errmsg_internal("\t%s", *p))); 956 ereport(DEBUG3, 957 (errmsg_internal("-----------------------------------------"))); 958 } 959 960 /* 961 * Create lockfile for data directory. 962 * 963 * We want to do this before we try to grab the input sockets, because the 964 * data directory interlock is more reliable than the socket-file 965 * interlock (thanks to whoever decided to put socket files in /tmp :-(). 966 * For the same reason, it's best to grab the TCP socket(s) before the 967 * Unix socket(s). 968 * 969 * Also note that this internally sets up the on_proc_exit function that 970 * is responsible for removing both data directory and socket lockfiles; 971 * so it must happen before opening sockets so that at exit, the socket 972 * lockfiles go away after CloseServerPorts runs. 973 */ 974 CreateDataDirLockFile(true); 975 976 /* 977 * Read the control file (for error checking and config info). 978 * 979 * Since we verify the control file's CRC, this has a useful side effect 980 * on machines where we need a run-time test for CRC support instructions. 981 * The postmaster will do the test once at startup, and then its child 982 * processes will inherit the correct function pointer and not need to 983 * repeat the test. 984 */ 985 LocalProcessControlFile(false); 986 987 /* 988 * Initialize SSL library, if specified. 989 */ 990 #ifdef USE_SSL 991 if (EnableSSL) 992 { 993 (void) secure_initialize(true); 994 LoadedSSL = true; 995 } 996 #endif 997 998 /* 999 * Register the apply launcher. Since it registers a background worker, 1000 * it needs to be called before InitializeMaxBackends(), and it's probably 1001 * a good idea to call it before any modules had chance to take the 1002 * background worker slots. 1003 */ 1004 ApplyLauncherRegister(); 1005 1006 /* 1007 * process any libraries that should be preloaded at postmaster start 1008 */ 1009 process_shared_preload_libraries(); 1010 1011 /* 1012 * Now that loadable modules have had their chance to register background 1013 * workers, calculate MaxBackends. 1014 */ 1015 InitializeMaxBackends(); 1016 1017 /* Report server startup in log */ 1018 ereport(LOG, 1019 (errmsg("starting %s", PG_VERSION_STR))); 1020 1021 /* 1022 * Establish input sockets. 1023 * 1024 * First, mark them all closed, and set up an on_proc_exit function that's 1025 * charged with closing the sockets again at postmaster shutdown. 1026 */ 1027 for (i = 0; i < MAXLISTEN; i++) 1028 ListenSocket[i] = PGINVALID_SOCKET; 1029 1030 on_proc_exit(CloseServerPorts, 0); 1031 1032 if (ListenAddresses) 1033 { 1034 char *rawstring; 1035 List *elemlist; 1036 ListCell *l; 1037 int success = 0; 1038 1039 /* Need a modifiable copy of ListenAddresses */ 1040 rawstring = pstrdup(ListenAddresses); 1041 1042 /* Parse string into list of hostnames */ 1043 if (!SplitIdentifierString(rawstring, ',', &elemlist)) 1044 { 1045 /* syntax error in list */ 1046 ereport(FATAL, 1047 (errcode(ERRCODE_INVALID_PARAMETER_VALUE), 1048 errmsg("invalid list syntax in parameter \"%s\"", 1049 "listen_addresses"))); 1050 } 1051 1052 foreach(l, elemlist) 1053 { 1054 char *curhost = (char *) lfirst(l); 1055 1056 if (strcmp(curhost, "*") == 0) 1057 status = StreamServerPort(AF_UNSPEC, NULL, 1058 (unsigned short) PostPortNumber, 1059 NULL, 1060 ListenSocket, MAXLISTEN); 1061 else 1062 status = StreamServerPort(AF_UNSPEC, curhost, 1063 (unsigned short) PostPortNumber, 1064 NULL, 1065 ListenSocket, MAXLISTEN); 1066 1067 if (status == STATUS_OK) 1068 { 1069 success++; 1070 /* record the first successful host addr in lockfile */ 1071 if (!listen_addr_saved) 1072 { 1073 AddToDataDirLockFile(LOCK_FILE_LINE_LISTEN_ADDR, curhost); 1074 listen_addr_saved = true; 1075 } 1076 } 1077 else 1078 ereport(WARNING, 1079 (errmsg("could not create listen socket for \"%s\"", 1080 curhost))); 1081 } 1082 1083 if (!success && elemlist != NIL) 1084 ereport(FATAL, 1085 (errmsg("could not create any TCP/IP sockets"))); 1086 1087 list_free(elemlist); 1088 pfree(rawstring); 1089 } 1090 1091 #ifdef USE_BONJOUR 1092 /* Register for Bonjour only if we opened TCP socket(s) */ 1093 if (enable_bonjour && ListenSocket[0] != PGINVALID_SOCKET) 1094 { 1095 DNSServiceErrorType err; 1096 1097 /* 1098 * We pass 0 for interface_index, which will result in registering on 1099 * all "applicable" interfaces. It's not entirely clear from the 1100 * DNS-SD docs whether this would be appropriate if we have bound to 1101 * just a subset of the available network interfaces. 1102 */ 1103 err = DNSServiceRegister(&bonjour_sdref, 1104 0, 1105 0, 1106 bonjour_name, 1107 "_postgresql._tcp.", 1108 NULL, 1109 NULL, 1110 pg_hton16(PostPortNumber), 1111 0, 1112 NULL, 1113 NULL, 1114 NULL); 1115 if (err != kDNSServiceErr_NoError) 1116 elog(LOG, "DNSServiceRegister() failed: error code %ld", 1117 (long) err); 1118 1119 /* 1120 * We don't bother to read the mDNS daemon's reply, and we expect that 1121 * it will automatically terminate our registration when the socket is 1122 * closed at postmaster termination. So there's nothing more to be 1123 * done here. However, the bonjour_sdref is kept around so that 1124 * forked children can close their copies of the socket. 1125 */ 1126 } 1127 #endif 1128 1129 #ifdef HAVE_UNIX_SOCKETS 1130 if (Unix_socket_directories) 1131 { 1132 char *rawstring; 1133 List *elemlist; 1134 ListCell *l; 1135 int success = 0; 1136 1137 /* Need a modifiable copy of Unix_socket_directories */ 1138 rawstring = pstrdup(Unix_socket_directories); 1139 1140 /* Parse string into list of directories */ 1141 if (!SplitDirectoriesString(rawstring, ',', &elemlist)) 1142 { 1143 /* syntax error in list */ 1144 ereport(FATAL, 1145 (errcode(ERRCODE_INVALID_PARAMETER_VALUE), 1146 errmsg("invalid list syntax in parameter \"%s\"", 1147 "unix_socket_directories"))); 1148 } 1149 1150 foreach(l, elemlist) 1151 { 1152 char *socketdir = (char *) lfirst(l); 1153 1154 status = StreamServerPort(AF_UNIX, NULL, 1155 (unsigned short) PostPortNumber, 1156 socketdir, 1157 ListenSocket, MAXLISTEN); 1158 1159 if (status == STATUS_OK) 1160 { 1161 success++; 1162 /* record the first successful Unix socket in lockfile */ 1163 if (success == 1) 1164 AddToDataDirLockFile(LOCK_FILE_LINE_SOCKET_DIR, socketdir); 1165 } 1166 else 1167 ereport(WARNING, 1168 (errmsg("could not create Unix-domain socket in directory \"%s\"", 1169 socketdir))); 1170 } 1171 1172 if (!success && elemlist != NIL) 1173 ereport(FATAL, 1174 (errmsg("could not create any Unix-domain sockets"))); 1175 1176 list_free_deep(elemlist); 1177 pfree(rawstring); 1178 } 1179 #endif 1180 1181 /* 1182 * check that we have some socket to listen on 1183 */ 1184 if (ListenSocket[0] == PGINVALID_SOCKET) 1185 ereport(FATAL, 1186 (errmsg("no socket created for listening"))); 1187 1188 /* 1189 * If no valid TCP ports, write an empty line for listen address, 1190 * indicating the Unix socket must be used. Note that this line is not 1191 * added to the lock file until there is a socket backing it. 1192 */ 1193 if (!listen_addr_saved) 1194 AddToDataDirLockFile(LOCK_FILE_LINE_LISTEN_ADDR, ""); 1195 1196 /* 1197 * Set up shared memory and semaphores. 1198 */ 1199 reset_shared(PostPortNumber); 1200 1201 /* 1202 * Estimate number of openable files. This must happen after setting up 1203 * semaphores, because on some platforms semaphores count as open files. 1204 */ 1205 set_max_safe_fds(); 1206 1207 /* 1208 * Set reference point for stack-depth checking. 1209 */ 1210 set_stack_base(); 1211 1212 /* 1213 * Initialize pipe (or process handle on Windows) that allows children to 1214 * wake up from sleep on postmaster death. 1215 */ 1216 InitPostmasterDeathWatchHandle(); 1217 1218 #ifdef WIN32 1219 1220 /* 1221 * Initialize I/O completion port used to deliver list of dead children. 1222 */ 1223 win32ChildQueue = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 1); 1224 if (win32ChildQueue == NULL) 1225 ereport(FATAL, 1226 (errmsg("could not create I/O completion port for child queue"))); 1227 #endif 1228 1229 /* 1230 * Record postmaster options. We delay this till now to avoid recording 1231 * bogus options (eg, NBuffers too high for available memory). 1232 */ 1233 if (!CreateOptsFile(argc, argv, my_exec_path)) 1234 ExitPostmaster(1); 1235 1236 #ifdef EXEC_BACKEND 1237 /* Write out nondefault GUC settings for child processes to use */ 1238 write_nondefault_variables(PGC_POSTMASTER); 1239 #endif 1240 1241 /* 1242 * Write the external PID file if requested 1243 */ 1244 if (external_pid_file) 1245 { 1246 FILE *fpidfile = fopen(external_pid_file, "w"); 1247 1248 if (fpidfile) 1249 { 1250 fprintf(fpidfile, "%d\n", MyProcPid); 1251 fclose(fpidfile); 1252 1253 /* Make PID file world readable */ 1254 if (chmod(external_pid_file, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH) != 0) 1255 write_stderr("%s: could not change permissions of external PID file \"%s\": %s\n", 1256 progname, external_pid_file, strerror(errno)); 1257 } 1258 else 1259 write_stderr("%s: could not write external PID file \"%s\": %s\n", 1260 progname, external_pid_file, strerror(errno)); 1261 1262 on_proc_exit(unlink_external_pid_file, 0); 1263 } 1264 1265 /* 1266 * Remove old temporary files. At this point there can be no other 1267 * Postgres processes running in this directory, so this should be safe. 1268 */ 1269 RemovePgTempFiles(); 1270 1271 /* 1272 * Forcibly remove the files signaling a standby promotion request. 1273 * Otherwise, the existence of those files triggers a promotion too early, 1274 * whether a user wants that or not. 1275 * 1276 * This removal of files is usually unnecessary because they can exist 1277 * only during a few moments during a standby promotion. However there is 1278 * a race condition: if pg_ctl promote is executed and creates the files 1279 * during a promotion, the files can stay around even after the server is 1280 * brought up to new master. Then, if new standby starts by using the 1281 * backup taken from that master, the files can exist at the server 1282 * startup and should be removed in order to avoid an unexpected 1283 * promotion. 1284 * 1285 * Note that promotion signal files need to be removed before the startup 1286 * process is invoked. Because, after that, they can be used by 1287 * postmaster's SIGUSR1 signal handler. 1288 */ 1289 RemovePromoteSignalFiles(); 1290 1291 /* Do the same for logrotate signal file */ 1292 RemoveLogrotateSignalFiles(); 1293 1294 /* Remove any outdated file holding the current log filenames. */ 1295 if (unlink(LOG_METAINFO_DATAFILE) < 0 && errno != ENOENT) 1296 ereport(LOG, 1297 (errcode_for_file_access(), 1298 errmsg("could not remove file \"%s\": %m", 1299 LOG_METAINFO_DATAFILE))); 1300 1301 /* 1302 * If enabled, start up syslogger collection subprocess 1303 */ 1304 SysLoggerPID = SysLogger_Start(); 1305 1306 /* 1307 * Reset whereToSendOutput from DestDebug (its starting state) to 1308 * DestNone. This stops ereport from sending log messages to stderr unless 1309 * Log_destination permits. We don't do this until the postmaster is 1310 * fully launched, since startup failures may as well be reported to 1311 * stderr. 1312 * 1313 * If we are in fact disabling logging to stderr, first emit a log message 1314 * saying so, to provide a breadcrumb trail for users who may not remember 1315 * that their logging is configured to go somewhere else. 1316 */ 1317 if (!(Log_destination & LOG_DESTINATION_STDERR)) 1318 ereport(LOG, 1319 (errmsg("ending log output to stderr"), 1320 errhint("Future log output will go to log destination \"%s\".", 1321 Log_destination_string))); 1322 1323 whereToSendOutput = DestNone; 1324 1325 /* 1326 * Initialize stats collection subsystem (this does NOT start the 1327 * collector process!) 1328 */ 1329 pgstat_init(); 1330 1331 /* 1332 * Initialize the autovacuum subsystem (again, no process start yet) 1333 */ 1334 autovac_init(); 1335 1336 /* 1337 * Load configuration files for client authentication. 1338 */ 1339 if (!load_hba()) 1340 { 1341 /* 1342 * It makes no sense to continue if we fail to load the HBA file, 1343 * since there is no way to connect to the database in this case. 1344 */ 1345 ereport(FATAL, 1346 (errmsg("could not load pg_hba.conf"))); 1347 } 1348 if (!load_ident()) 1349 { 1350 /* 1351 * We can start up without the IDENT file, although it means that you 1352 * cannot log in using any of the authentication methods that need a 1353 * user name mapping. load_ident() already logged the details of error 1354 * to the log. 1355 */ 1356 } 1357 1358 #ifdef HAVE_PTHREAD_IS_THREADED_NP 1359 1360 /* 1361 * On macOS, libintl replaces setlocale() with a version that calls 1362 * CFLocaleCopyCurrent() when its second argument is "" and every relevant 1363 * environment variable is unset or empty. CFLocaleCopyCurrent() makes 1364 * the process multithreaded. The postmaster calls sigprocmask() and 1365 * calls fork() without an immediate exec(), both of which have undefined 1366 * behavior in a multithreaded program. A multithreaded postmaster is the 1367 * normal case on Windows, which offers neither fork() nor sigprocmask(). 1368 */ 1369 if (pthread_is_threaded_np() != 0) 1370 ereport(FATAL, 1371 (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), 1372 errmsg("postmaster became multithreaded during startup"), 1373 errhint("Set the LC_ALL environment variable to a valid locale."))); 1374 #endif 1375 1376 /* 1377 * Remember postmaster startup time 1378 */ 1379 PgStartTime = GetCurrentTimestamp(); 1380 1381 /* 1382 * Report postmaster status in the postmaster.pid file, to allow pg_ctl to 1383 * see what's happening. 1384 */ 1385 AddToDataDirLockFile(LOCK_FILE_LINE_PM_STATUS, PM_STATUS_STARTING); 1386 1387 /* 1388 * We're ready to rock and roll... 1389 */ 1390 StartupPID = StartupDataBase(); 1391 Assert(StartupPID != 0); 1392 StartupStatus = STARTUP_RUNNING; 1393 pmState = PM_STARTUP; 1394 1395 /* Some workers may be scheduled to start now */ 1396 maybe_start_bgworkers(); 1397 1398 status = ServerLoop(); 1399 1400 /* 1401 * ServerLoop probably shouldn't ever return, but if it does, close down. 1402 */ 1403 ExitPostmaster(status != STATUS_OK); 1404 1405 abort(); /* not reached */ 1406 } 1407 1408 1409 /* 1410 * on_proc_exit callback to close server's listen sockets 1411 */ 1412 static void 1413 CloseServerPorts(int status, Datum arg) 1414 { 1415 int i; 1416 1417 /* 1418 * First, explicitly close all the socket FDs. We used to just let this 1419 * happen implicitly at postmaster exit, but it's better to close them 1420 * before we remove the postmaster.pid lockfile; otherwise there's a race 1421 * condition if a new postmaster wants to re-use the TCP port number. 1422 */ 1423 for (i = 0; i < MAXLISTEN; i++) 1424 { 1425 if (ListenSocket[i] != PGINVALID_SOCKET) 1426 { 1427 StreamClose(ListenSocket[i]); 1428 ListenSocket[i] = PGINVALID_SOCKET; 1429 } 1430 } 1431 1432 /* 1433 * Next, remove any filesystem entries for Unix sockets. To avoid race 1434 * conditions against incoming postmasters, this must happen after closing 1435 * the sockets and before removing lock files. 1436 */ 1437 RemoveSocketFiles(); 1438 1439 /* 1440 * We don't do anything about socket lock files here; those will be 1441 * removed in a later on_proc_exit callback. 1442 */ 1443 } 1444 1445 /* 1446 * on_proc_exit callback to delete external_pid_file 1447 */ 1448 static void 1449 unlink_external_pid_file(int status, Datum arg) 1450 { 1451 if (external_pid_file) 1452 unlink(external_pid_file); 1453 } 1454 1455 1456 /* 1457 * Compute and check the directory paths to files that are part of the 1458 * installation (as deduced from the postgres executable's own location) 1459 */ 1460 static void 1461 getInstallationPaths(const char *argv0) 1462 { 1463 DIR *pdir; 1464 1465 /* Locate the postgres executable itself */ 1466 if (find_my_exec(argv0, my_exec_path) < 0) 1467 elog(FATAL, "%s: could not locate my own executable path", argv0); 1468 1469 #ifdef EXEC_BACKEND 1470 /* Locate executable backend before we change working directory */ 1471 if (find_other_exec(argv0, "postgres", PG_BACKEND_VERSIONSTR, 1472 postgres_exec_path) < 0) 1473 ereport(FATAL, 1474 (errmsg("%s: could not locate matching postgres executable", 1475 argv0))); 1476 #endif 1477 1478 /* 1479 * Locate the pkglib directory --- this has to be set early in case we try 1480 * to load any modules from it in response to postgresql.conf entries. 1481 */ 1482 get_pkglib_path(my_exec_path, pkglib_path); 1483 1484 /* 1485 * Verify that there's a readable directory there; otherwise the Postgres 1486 * installation is incomplete or corrupt. (A typical cause of this 1487 * failure is that the postgres executable has been moved or hardlinked to 1488 * some directory that's not a sibling of the installation lib/ 1489 * directory.) 1490 */ 1491 pdir = AllocateDir(pkglib_path); 1492 if (pdir == NULL) 1493 ereport(ERROR, 1494 (errcode_for_file_access(), 1495 errmsg("could not open directory \"%s\": %m", 1496 pkglib_path), 1497 errhint("This may indicate an incomplete PostgreSQL installation, or that the file \"%s\" has been moved away from its proper location.", 1498 my_exec_path))); 1499 FreeDir(pdir); 1500 1501 /* 1502 * XXX is it worth similarly checking the share/ directory? If the lib/ 1503 * directory is there, then share/ probably is too. 1504 */ 1505 } 1506 1507 /* 1508 * Check that pg_control exists in the correct location in the data directory. 1509 * 1510 * No attempt is made to validate the contents of pg_control here. This is 1511 * just a sanity check to see if we are looking at a real data directory. 1512 */ 1513 static void 1514 checkControlFile(void) 1515 { 1516 char path[MAXPGPATH]; 1517 FILE *fp; 1518 1519 snprintf(path, sizeof(path), "%s/global/pg_control", DataDir); 1520 1521 fp = AllocateFile(path, PG_BINARY_R); 1522 if (fp == NULL) 1523 { 1524 write_stderr("%s: could not find the database system\n" 1525 "Expected to find it in the directory \"%s\",\n" 1526 "but could not open file \"%s\": %s\n", 1527 progname, DataDir, path, strerror(errno)); 1528 ExitPostmaster(2); 1529 } 1530 FreeFile(fp); 1531 } 1532 1533 /* 1534 * Determine how long should we let ServerLoop sleep. 1535 * 1536 * In normal conditions we wait at most one minute, to ensure that the other 1537 * background tasks handled by ServerLoop get done even when no requests are 1538 * arriving. However, if there are background workers waiting to be started, 1539 * we don't actually sleep so that they are quickly serviced. Other exception 1540 * cases are as shown in the code. 1541 */ 1542 static void 1543 DetermineSleepTime(struct timeval *timeout) 1544 { 1545 TimestampTz next_wakeup = 0; 1546 1547 /* 1548 * Normal case: either there are no background workers at all, or we're in 1549 * a shutdown sequence (during which we ignore bgworkers altogether). 1550 */ 1551 if (Shutdown > NoShutdown || 1552 (!StartWorkerNeeded && !HaveCrashedWorker)) 1553 { 1554 if (AbortStartTime != 0) 1555 { 1556 /* time left to abort; clamp to 0 in case it already expired */ 1557 timeout->tv_sec = SIGKILL_CHILDREN_AFTER_SECS - 1558 (time(NULL) - AbortStartTime); 1559 timeout->tv_sec = Max(timeout->tv_sec, 0); 1560 timeout->tv_usec = 0; 1561 } 1562 else 1563 { 1564 timeout->tv_sec = 60; 1565 timeout->tv_usec = 0; 1566 } 1567 return; 1568 } 1569 1570 if (StartWorkerNeeded) 1571 { 1572 timeout->tv_sec = 0; 1573 timeout->tv_usec = 0; 1574 return; 1575 } 1576 1577 if (HaveCrashedWorker) 1578 { 1579 slist_mutable_iter siter; 1580 1581 /* 1582 * When there are crashed bgworkers, we sleep just long enough that 1583 * they are restarted when they request to be. Scan the list to 1584 * determine the minimum of all wakeup times according to most recent 1585 * crash time and requested restart interval. 1586 */ 1587 slist_foreach_modify(siter, &BackgroundWorkerList) 1588 { 1589 RegisteredBgWorker *rw; 1590 TimestampTz this_wakeup; 1591 1592 rw = slist_container(RegisteredBgWorker, rw_lnode, siter.cur); 1593 1594 if (rw->rw_crashed_at == 0) 1595 continue; 1596 1597 if (rw->rw_worker.bgw_restart_time == BGW_NEVER_RESTART 1598 || rw->rw_terminate) 1599 { 1600 ForgetBackgroundWorker(&siter); 1601 continue; 1602 } 1603 1604 this_wakeup = TimestampTzPlusMilliseconds(rw->rw_crashed_at, 1605 1000L * rw->rw_worker.bgw_restart_time); 1606 if (next_wakeup == 0 || this_wakeup < next_wakeup) 1607 next_wakeup = this_wakeup; 1608 } 1609 } 1610 1611 if (next_wakeup != 0) 1612 { 1613 long secs; 1614 int microsecs; 1615 1616 TimestampDifference(GetCurrentTimestamp(), next_wakeup, 1617 &secs, µsecs); 1618 timeout->tv_sec = secs; 1619 timeout->tv_usec = microsecs; 1620 1621 /* Ensure we don't exceed one minute */ 1622 if (timeout->tv_sec > 60) 1623 { 1624 timeout->tv_sec = 60; 1625 timeout->tv_usec = 0; 1626 } 1627 } 1628 else 1629 { 1630 timeout->tv_sec = 60; 1631 timeout->tv_usec = 0; 1632 } 1633 } 1634 1635 /* 1636 * Main idle loop of postmaster 1637 * 1638 * NB: Needs to be called with signals blocked 1639 */ 1640 static int 1641 ServerLoop(void) 1642 { 1643 fd_set readmask; 1644 int nSockets; 1645 time_t last_lockfile_recheck_time, 1646 last_touch_time; 1647 1648 last_lockfile_recheck_time = last_touch_time = time(NULL); 1649 1650 nSockets = initMasks(&readmask); 1651 1652 for (;;) 1653 { 1654 fd_set rmask; 1655 int selres; 1656 time_t now; 1657 1658 /* 1659 * Wait for a connection request to arrive. 1660 * 1661 * We block all signals except while sleeping. That makes it safe for 1662 * signal handlers, which again block all signals while executing, to 1663 * do nontrivial work. 1664 * 1665 * If we are in PM_WAIT_DEAD_END state, then we don't want to accept 1666 * any new connections, so we don't call select(), and just sleep. 1667 */ 1668 memcpy((char *) &rmask, (char *) &readmask, sizeof(fd_set)); 1669 1670 if (pmState == PM_WAIT_DEAD_END) 1671 { 1672 PG_SETMASK(&UnBlockSig); 1673 1674 pg_usleep(100000L); /* 100 msec seems reasonable */ 1675 selres = 0; 1676 1677 PG_SETMASK(&BlockSig); 1678 } 1679 else 1680 { 1681 /* must set timeout each time; some OSes change it! */ 1682 struct timeval timeout; 1683 1684 /* Needs to run with blocked signals! */ 1685 DetermineSleepTime(&timeout); 1686 1687 PG_SETMASK(&UnBlockSig); 1688 1689 selres = select(nSockets, &rmask, NULL, NULL, &timeout); 1690 1691 PG_SETMASK(&BlockSig); 1692 } 1693 1694 /* Now check the select() result */ 1695 if (selres < 0) 1696 { 1697 if (errno != EINTR && errno != EWOULDBLOCK) 1698 { 1699 ereport(LOG, 1700 (errcode_for_socket_access(), 1701 errmsg("select() failed in postmaster: %m"))); 1702 return STATUS_ERROR; 1703 } 1704 } 1705 1706 /* 1707 * New connection pending on any of our sockets? If so, fork a child 1708 * process to deal with it. 1709 */ 1710 if (selres > 0) 1711 { 1712 int i; 1713 1714 for (i = 0; i < MAXLISTEN; i++) 1715 { 1716 if (ListenSocket[i] == PGINVALID_SOCKET) 1717 break; 1718 if (FD_ISSET(ListenSocket[i], &rmask)) 1719 { 1720 Port *port; 1721 1722 port = ConnCreate(ListenSocket[i]); 1723 if (port) 1724 { 1725 BackendStartup(port); 1726 1727 /* 1728 * We no longer need the open socket or port structure 1729 * in this process 1730 */ 1731 StreamClose(port->sock); 1732 ConnFree(port); 1733 } 1734 } 1735 } 1736 } 1737 1738 /* If we have lost the log collector, try to start a new one */ 1739 if (SysLoggerPID == 0 && Logging_collector) 1740 SysLoggerPID = SysLogger_Start(); 1741 1742 /* 1743 * If no background writer process is running, and we are not in a 1744 * state that prevents it, start one. It doesn't matter if this 1745 * fails, we'll just try again later. Likewise for the checkpointer. 1746 */ 1747 if (pmState == PM_RUN || pmState == PM_RECOVERY || 1748 pmState == PM_HOT_STANDBY) 1749 { 1750 if (CheckpointerPID == 0) 1751 CheckpointerPID = StartCheckpointer(); 1752 if (BgWriterPID == 0) 1753 BgWriterPID = StartBackgroundWriter(); 1754 } 1755 1756 /* 1757 * Likewise, if we have lost the walwriter process, try to start a new 1758 * one. But this is needed only in normal operation (else we cannot 1759 * be writing any new WAL). 1760 */ 1761 if (WalWriterPID == 0 && pmState == PM_RUN) 1762 WalWriterPID = StartWalWriter(); 1763 1764 /* 1765 * If we have lost the autovacuum launcher, try to start a new one. We 1766 * don't want autovacuum to run in binary upgrade mode because 1767 * autovacuum might update relfrozenxid for empty tables before the 1768 * physical files are put in place. 1769 */ 1770 if (!IsBinaryUpgrade && AutoVacPID == 0 && 1771 (AutoVacuumingActive() || start_autovac_launcher) && 1772 pmState == PM_RUN) 1773 { 1774 AutoVacPID = StartAutoVacLauncher(); 1775 if (AutoVacPID != 0) 1776 start_autovac_launcher = false; /* signal processed */ 1777 } 1778 1779 /* If we have lost the stats collector, try to start a new one */ 1780 if (PgStatPID == 0 && 1781 (pmState == PM_RUN || pmState == PM_HOT_STANDBY)) 1782 PgStatPID = pgstat_start(); 1783 1784 /* If we have lost the archiver, try to start a new one. */ 1785 if (PgArchPID == 0 && PgArchStartupAllowed()) 1786 PgArchPID = pgarch_start(); 1787 1788 /* If we need to signal the autovacuum launcher, do so now */ 1789 if (avlauncher_needs_signal) 1790 { 1791 avlauncher_needs_signal = false; 1792 if (AutoVacPID != 0) 1793 kill(AutoVacPID, SIGUSR2); 1794 } 1795 1796 /* If we need to start a WAL receiver, try to do that now */ 1797 if (WalReceiverRequested) 1798 MaybeStartWalReceiver(); 1799 1800 /* Get other worker processes running, if needed */ 1801 if (StartWorkerNeeded || HaveCrashedWorker) 1802 maybe_start_bgworkers(); 1803 1804 #ifdef HAVE_PTHREAD_IS_THREADED_NP 1805 1806 /* 1807 * With assertions enabled, check regularly for appearance of 1808 * additional threads. All builds check at start and exit. 1809 */ 1810 Assert(pthread_is_threaded_np() == 0); 1811 #endif 1812 1813 /* 1814 * Lastly, check to see if it's time to do some things that we don't 1815 * want to do every single time through the loop, because they're a 1816 * bit expensive. Note that there's up to a minute of slop in when 1817 * these tasks will be performed, since DetermineSleepTime() will let 1818 * us sleep at most that long; except for SIGKILL timeout which has 1819 * special-case logic there. 1820 */ 1821 now = time(NULL); 1822 1823 /* 1824 * If we already sent SIGQUIT to children and they are slow to shut 1825 * down, it's time to send them SIGKILL. This doesn't happen 1826 * normally, but under certain conditions backends can get stuck while 1827 * shutting down. This is a last measure to get them unwedged. 1828 * 1829 * Note we also do this during recovery from a process crash. 1830 */ 1831 if ((Shutdown >= ImmediateShutdown || (FatalError && !SendStop)) && 1832 AbortStartTime != 0 && 1833 (now - AbortStartTime) >= SIGKILL_CHILDREN_AFTER_SECS) 1834 { 1835 /* We were gentle with them before. Not anymore */ 1836 TerminateChildren(SIGKILL); 1837 /* reset flag so we don't SIGKILL again */ 1838 AbortStartTime = 0; 1839 } 1840 1841 /* 1842 * Once a minute, verify that postmaster.pid hasn't been removed or 1843 * overwritten. If it has, we force a shutdown. This avoids having 1844 * postmasters and child processes hanging around after their database 1845 * is gone, and maybe causing problems if a new database cluster is 1846 * created in the same place. It also provides some protection 1847 * against a DBA foolishly removing postmaster.pid and manually 1848 * starting a new postmaster. Data corruption is likely to ensue from 1849 * that anyway, but we can minimize the damage by aborting ASAP. 1850 */ 1851 if (now - last_lockfile_recheck_time >= 1 * SECS_PER_MINUTE) 1852 { 1853 if (!RecheckDataDirLockFile()) 1854 { 1855 ereport(LOG, 1856 (errmsg("performing immediate shutdown because data directory lock file is invalid"))); 1857 kill(MyProcPid, SIGQUIT); 1858 } 1859 last_lockfile_recheck_time = now; 1860 } 1861 1862 /* 1863 * Touch Unix socket and lock files every 58 minutes, to ensure that 1864 * they are not removed by overzealous /tmp-cleaning tasks. We assume 1865 * no one runs cleaners with cutoff times of less than an hour ... 1866 */ 1867 if (now - last_touch_time >= 58 * SECS_PER_MINUTE) 1868 { 1869 TouchSocketFiles(); 1870 TouchSocketLockFiles(); 1871 last_touch_time = now; 1872 } 1873 } 1874 } 1875 1876 /* 1877 * Initialise the masks for select() for the ports we are listening on. 1878 * Return the number of sockets to listen on. 1879 */ 1880 static int 1881 initMasks(fd_set *rmask) 1882 { 1883 int maxsock = -1; 1884 int i; 1885 1886 FD_ZERO(rmask); 1887 1888 for (i = 0; i < MAXLISTEN; i++) 1889 { 1890 int fd = ListenSocket[i]; 1891 1892 if (fd == PGINVALID_SOCKET) 1893 break; 1894 FD_SET(fd, rmask); 1895 1896 if (fd > maxsock) 1897 maxsock = fd; 1898 } 1899 1900 return maxsock + 1; 1901 } 1902 1903 1904 /* 1905 * Read a client's startup packet and do something according to it. 1906 * 1907 * Returns STATUS_OK or STATUS_ERROR, or might call ereport(FATAL) and 1908 * not return at all. 1909 * 1910 * (Note that ereport(FATAL) stuff is sent to the client, so only use it 1911 * if that's what you want. Return STATUS_ERROR if you don't want to 1912 * send anything to the client, which would typically be appropriate 1913 * if we detect a communications failure.) 1914 * 1915 * Set ssl_done and/or gss_done when negotiation of an encrypted layer 1916 * (currently, TLS or GSSAPI) is completed. A successful negotiation of either 1917 * encryption layer sets both flags, but a rejected negotiation sets only the 1918 * flag for that layer, since the client may wish to try the other one. We 1919 * should make no assumption here about the order in which the client may make 1920 * requests. 1921 */ 1922 static int 1923 ProcessStartupPacket(Port *port, bool ssl_done, bool gss_done) 1924 { 1925 int32 len; 1926 void *buf; 1927 ProtocolVersion proto; 1928 MemoryContext oldcontext; 1929 1930 pq_startmsgread(); 1931 1932 /* 1933 * Grab the first byte of the length word separately, so that we can tell 1934 * whether we have no data at all or an incomplete packet. (This might 1935 * sound inefficient, but it's not really, because of buffering in 1936 * pqcomm.c.) 1937 */ 1938 if (pq_getbytes((char *) &len, 1) == EOF) 1939 { 1940 /* 1941 * If we get no data at all, don't clutter the log with a complaint; 1942 * such cases often occur for legitimate reasons. An example is that 1943 * we might be here after responding to NEGOTIATE_SSL_CODE, and if the 1944 * client didn't like our response, it'll probably just drop the 1945 * connection. Service-monitoring software also often just opens and 1946 * closes a connection without sending anything. (So do port 1947 * scanners, which may be less benign, but it's not really our job to 1948 * notice those.) 1949 */ 1950 return STATUS_ERROR; 1951 } 1952 1953 if (pq_getbytes(((char *) &len) + 1, 3) == EOF) 1954 { 1955 /* Got a partial length word, so bleat about that */ 1956 if (!ssl_done && !gss_done) 1957 ereport(COMMERROR, 1958 (errcode(ERRCODE_PROTOCOL_VIOLATION), 1959 errmsg("incomplete startup packet"))); 1960 return STATUS_ERROR; 1961 } 1962 1963 len = pg_ntoh32(len); 1964 len -= 4; 1965 1966 if (len < (int32) sizeof(ProtocolVersion) || 1967 len > MAX_STARTUP_PACKET_LENGTH) 1968 { 1969 ereport(COMMERROR, 1970 (errcode(ERRCODE_PROTOCOL_VIOLATION), 1971 errmsg("invalid length of startup packet"))); 1972 return STATUS_ERROR; 1973 } 1974 1975 /* 1976 * Allocate at least the size of an old-style startup packet, plus one 1977 * extra byte, and make sure all are zeroes. This ensures we will have 1978 * null termination of all strings, in both fixed- and variable-length 1979 * packet layouts. 1980 */ 1981 if (len <= (int32) sizeof(StartupPacket)) 1982 buf = palloc0(sizeof(StartupPacket) + 1); 1983 else 1984 buf = palloc0(len + 1); 1985 1986 if (pq_getbytes(buf, len) == EOF) 1987 { 1988 ereport(COMMERROR, 1989 (errcode(ERRCODE_PROTOCOL_VIOLATION), 1990 errmsg("incomplete startup packet"))); 1991 return STATUS_ERROR; 1992 } 1993 pq_endmsgread(); 1994 1995 /* 1996 * The first field is either a protocol version number or a special 1997 * request code. 1998 */ 1999 port->proto = proto = pg_ntoh32(*((ProtocolVersion *) buf)); 2000 2001 if (proto == CANCEL_REQUEST_CODE) 2002 { 2003 processCancelRequest(port, buf); 2004 /* Not really an error, but we don't want to proceed further */ 2005 return STATUS_ERROR; 2006 } 2007 2008 if (proto == NEGOTIATE_SSL_CODE && !ssl_done) 2009 { 2010 char SSLok; 2011 2012 #ifdef USE_SSL 2013 /* No SSL when disabled or on Unix sockets */ 2014 if (!LoadedSSL || IS_AF_UNIX(port->laddr.addr.ss_family)) 2015 SSLok = 'N'; 2016 else 2017 SSLok = 'S'; /* Support for SSL */ 2018 #else 2019 SSLok = 'N'; /* No support for SSL */ 2020 #endif 2021 2022 retry1: 2023 if (send(port->sock, &SSLok, 1, 0) != 1) 2024 { 2025 if (errno == EINTR) 2026 goto retry1; /* if interrupted, just retry */ 2027 ereport(COMMERROR, 2028 (errcode_for_socket_access(), 2029 errmsg("failed to send SSL negotiation response: %m"))); 2030 return STATUS_ERROR; /* close the connection */ 2031 } 2032 2033 #ifdef USE_SSL 2034 if (SSLok == 'S' && secure_open_server(port) == -1) 2035 return STATUS_ERROR; 2036 #endif 2037 2038 /* 2039 * At this point we should have no data already buffered. If we do, 2040 * it was received before we performed the SSL handshake, so it wasn't 2041 * encrypted and indeed may have been injected by a man-in-the-middle. 2042 * We report this case to the client. 2043 */ 2044 if (pq_buffer_has_data()) 2045 ereport(FATAL, 2046 (errcode(ERRCODE_PROTOCOL_VIOLATION), 2047 errmsg("received unencrypted data after SSL request"), 2048 errdetail("This could be either a client-software bug or evidence of an attempted man-in-the-middle attack."))); 2049 2050 /* 2051 * regular startup packet, cancel, etc packet should follow, but not 2052 * another SSL negotiation request, and a GSS request should only 2053 * follow if SSL was rejected (client may negotiate in either order) 2054 */ 2055 return ProcessStartupPacket(port, true, SSLok == 'S'); 2056 } 2057 else if (proto == NEGOTIATE_GSS_CODE && !gss_done) 2058 { 2059 char GSSok = 'N'; 2060 2061 #ifdef ENABLE_GSS 2062 /* No GSSAPI encryption when on Unix socket */ 2063 if (!IS_AF_UNIX(port->laddr.addr.ss_family)) 2064 GSSok = 'G'; 2065 #endif 2066 2067 while (send(port->sock, &GSSok, 1, 0) != 1) 2068 { 2069 if (errno == EINTR) 2070 continue; 2071 ereport(COMMERROR, 2072 (errcode_for_socket_access(), 2073 errmsg("failed to send GSSAPI negotiation response: %m"))); 2074 return STATUS_ERROR; /* close the connection */ 2075 } 2076 2077 #ifdef ENABLE_GSS 2078 if (GSSok == 'G' && secure_open_gssapi(port) == -1) 2079 return STATUS_ERROR; 2080 #endif 2081 2082 /* 2083 * At this point we should have no data already buffered. If we do, 2084 * it was received before we performed the GSS handshake, so it wasn't 2085 * encrypted and indeed may have been injected by a man-in-the-middle. 2086 * We report this case to the client. 2087 */ 2088 if (pq_buffer_has_data()) 2089 ereport(FATAL, 2090 (errcode(ERRCODE_PROTOCOL_VIOLATION), 2091 errmsg("received unencrypted data after GSSAPI encryption request"), 2092 errdetail("This could be either a client-software bug or evidence of an attempted man-in-the-middle attack."))); 2093 2094 /* 2095 * regular startup packet, cancel, etc packet should follow, but not 2096 * another GSS negotiation request, and an SSL request should only 2097 * follow if GSS was rejected (client may negotiate in either order) 2098 */ 2099 return ProcessStartupPacket(port, GSSok == 'G', true); 2100 } 2101 2102 /* Could add additional special packet types here */ 2103 2104 /* 2105 * Set FrontendProtocol now so that ereport() knows what format to send if 2106 * we fail during startup. 2107 */ 2108 FrontendProtocol = proto; 2109 2110 /* Check that the major protocol version is in range. */ 2111 if (PG_PROTOCOL_MAJOR(proto) < PG_PROTOCOL_MAJOR(PG_PROTOCOL_EARLIEST) || 2112 PG_PROTOCOL_MAJOR(proto) > PG_PROTOCOL_MAJOR(PG_PROTOCOL_LATEST)) 2113 ereport(FATAL, 2114 (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), 2115 errmsg("unsupported frontend protocol %u.%u: server supports %u.0 to %u.%u", 2116 PG_PROTOCOL_MAJOR(proto), PG_PROTOCOL_MINOR(proto), 2117 PG_PROTOCOL_MAJOR(PG_PROTOCOL_EARLIEST), 2118 PG_PROTOCOL_MAJOR(PG_PROTOCOL_LATEST), 2119 PG_PROTOCOL_MINOR(PG_PROTOCOL_LATEST)))); 2120 2121 /* 2122 * Now fetch parameters out of startup packet and save them into the Port 2123 * structure. All data structures attached to the Port struct must be 2124 * allocated in TopMemoryContext so that they will remain available in a 2125 * running backend (even after PostmasterContext is destroyed). We need 2126 * not worry about leaking this storage on failure, since we aren't in the 2127 * postmaster process anymore. 2128 */ 2129 oldcontext = MemoryContextSwitchTo(TopMemoryContext); 2130 2131 if (PG_PROTOCOL_MAJOR(proto) >= 3) 2132 { 2133 int32 offset = sizeof(ProtocolVersion); 2134 List *unrecognized_protocol_options = NIL; 2135 2136 /* 2137 * Scan packet body for name/option pairs. We can assume any string 2138 * beginning within the packet body is null-terminated, thanks to 2139 * zeroing extra byte above. 2140 */ 2141 port->guc_options = NIL; 2142 2143 while (offset < len) 2144 { 2145 char *nameptr = ((char *) buf) + offset; 2146 int32 valoffset; 2147 char *valptr; 2148 2149 if (*nameptr == '\0') 2150 break; /* found packet terminator */ 2151 valoffset = offset + strlen(nameptr) + 1; 2152 if (valoffset >= len) 2153 break; /* missing value, will complain below */ 2154 valptr = ((char *) buf) + valoffset; 2155 2156 if (strcmp(nameptr, "database") == 0) 2157 port->database_name = pstrdup(valptr); 2158 else if (strcmp(nameptr, "user") == 0) 2159 port->user_name = pstrdup(valptr); 2160 else if (strcmp(nameptr, "options") == 0) 2161 port->cmdline_options = pstrdup(valptr); 2162 else if (strcmp(nameptr, "replication") == 0) 2163 { 2164 /* 2165 * Due to backward compatibility concerns the replication 2166 * parameter is a hybrid beast which allows the value to be 2167 * either boolean or the string 'database'. The latter 2168 * connects to a specific database which is e.g. required for 2169 * logical decoding while. 2170 */ 2171 if (strcmp(valptr, "database") == 0) 2172 { 2173 am_walsender = true; 2174 am_db_walsender = true; 2175 } 2176 else if (!parse_bool(valptr, &am_walsender)) 2177 ereport(FATAL, 2178 (errcode(ERRCODE_INVALID_PARAMETER_VALUE), 2179 errmsg("invalid value for parameter \"%s\": \"%s\"", 2180 "replication", 2181 valptr), 2182 errhint("Valid values are: \"false\", 0, \"true\", 1, \"database\"."))); 2183 } 2184 else if (strncmp(nameptr, "_pq_.", 5) == 0) 2185 { 2186 /* 2187 * Any option beginning with _pq_. is reserved for use as a 2188 * protocol-level option, but at present no such options are 2189 * defined. 2190 */ 2191 unrecognized_protocol_options = 2192 lappend(unrecognized_protocol_options, pstrdup(nameptr)); 2193 } 2194 else 2195 { 2196 /* Assume it's a generic GUC option */ 2197 port->guc_options = lappend(port->guc_options, 2198 pstrdup(nameptr)); 2199 port->guc_options = lappend(port->guc_options, 2200 pstrdup(valptr)); 2201 2202 /* 2203 * Copy application_name to port if we come across it. This 2204 * is done so we can log the application_name in the 2205 * connection authorization message. Note that the GUC would 2206 * be used but we haven't gone through GUC setup yet. 2207 */ 2208 if (strcmp(nameptr, "application_name") == 0) 2209 { 2210 char *tmp_app_name = pstrdup(valptr); 2211 2212 pg_clean_ascii(tmp_app_name); 2213 2214 port->application_name = tmp_app_name; 2215 } 2216 } 2217 offset = valoffset + strlen(valptr) + 1; 2218 } 2219 2220 /* 2221 * If we didn't find a packet terminator exactly at the end of the 2222 * given packet length, complain. 2223 */ 2224 if (offset != len - 1) 2225 ereport(FATAL, 2226 (errcode(ERRCODE_PROTOCOL_VIOLATION), 2227 errmsg("invalid startup packet layout: expected terminator as last byte"))); 2228 2229 /* 2230 * If the client requested a newer protocol version or if the client 2231 * requested any protocol options we didn't recognize, let them know 2232 * the newest minor protocol version we do support and the names of 2233 * any unrecognized options. 2234 */ 2235 if (PG_PROTOCOL_MINOR(proto) > PG_PROTOCOL_MINOR(PG_PROTOCOL_LATEST) || 2236 unrecognized_protocol_options != NIL) 2237 SendNegotiateProtocolVersion(unrecognized_protocol_options); 2238 } 2239 else 2240 { 2241 /* 2242 * Get the parameters from the old-style, fixed-width-fields startup 2243 * packet as C strings. The packet destination was cleared first so a 2244 * short packet has zeros silently added. We have to be prepared to 2245 * truncate the pstrdup result for oversize fields, though. 2246 */ 2247 StartupPacket *packet = (StartupPacket *) buf; 2248 2249 port->database_name = pstrdup(packet->database); 2250 if (strlen(port->database_name) > sizeof(packet->database)) 2251 port->database_name[sizeof(packet->database)] = '\0'; 2252 port->user_name = pstrdup(packet->user); 2253 if (strlen(port->user_name) > sizeof(packet->user)) 2254 port->user_name[sizeof(packet->user)] = '\0'; 2255 port->cmdline_options = pstrdup(packet->options); 2256 if (strlen(port->cmdline_options) > sizeof(packet->options)) 2257 port->cmdline_options[sizeof(packet->options)] = '\0'; 2258 port->guc_options = NIL; 2259 } 2260 2261 /* Check a user name was given. */ 2262 if (port->user_name == NULL || port->user_name[0] == '\0') 2263 ereport(FATAL, 2264 (errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION), 2265 errmsg("no PostgreSQL user name specified in startup packet"))); 2266 2267 /* The database defaults to the user name. */ 2268 if (port->database_name == NULL || port->database_name[0] == '\0') 2269 port->database_name = pstrdup(port->user_name); 2270 2271 if (Db_user_namespace) 2272 { 2273 /* 2274 * If user@, it is a global user, remove '@'. We only want to do this 2275 * if there is an '@' at the end and no earlier in the user string or 2276 * they may fake as a local user of another database attaching to this 2277 * database. 2278 */ 2279 if (strchr(port->user_name, '@') == 2280 port->user_name + strlen(port->user_name) - 1) 2281 *strchr(port->user_name, '@') = '\0'; 2282 else 2283 { 2284 /* Append '@' and dbname */ 2285 port->user_name = psprintf("%s@%s", port->user_name, port->database_name); 2286 } 2287 } 2288 2289 /* 2290 * Truncate given database and user names to length of a Postgres name. 2291 * This avoids lookup failures when overlength names are given. 2292 */ 2293 if (strlen(port->database_name) >= NAMEDATALEN) 2294 port->database_name[NAMEDATALEN - 1] = '\0'; 2295 if (strlen(port->user_name) >= NAMEDATALEN) 2296 port->user_name[NAMEDATALEN - 1] = '\0'; 2297 2298 /* 2299 * Normal walsender backends, e.g. for streaming replication, are not 2300 * connected to a particular database. But walsenders used for logical 2301 * replication need to connect to a specific database. We allow streaming 2302 * replication commands to be issued even if connected to a database as it 2303 * can make sense to first make a basebackup and then stream changes 2304 * starting from that. 2305 */ 2306 if (am_walsender && !am_db_walsender) 2307 port->database_name[0] = '\0'; 2308 2309 /* 2310 * Done putting stuff in TopMemoryContext. 2311 */ 2312 MemoryContextSwitchTo(oldcontext); 2313 2314 /* 2315 * If we're going to reject the connection due to database state, say so 2316 * now instead of wasting cycles on an authentication exchange. (This also 2317 * allows a pg_ping utility to be written.) 2318 */ 2319 switch (port->canAcceptConnections) 2320 { 2321 case CAC_STARTUP: 2322 ereport(FATAL, 2323 (errcode(ERRCODE_CANNOT_CONNECT_NOW), 2324 errmsg("the database system is starting up"))); 2325 break; 2326 case CAC_SHUTDOWN: 2327 ereport(FATAL, 2328 (errcode(ERRCODE_CANNOT_CONNECT_NOW), 2329 errmsg("the database system is shutting down"))); 2330 break; 2331 case CAC_RECOVERY: 2332 ereport(FATAL, 2333 (errcode(ERRCODE_CANNOT_CONNECT_NOW), 2334 errmsg("the database system is in recovery mode"))); 2335 break; 2336 case CAC_TOOMANY: 2337 ereport(FATAL, 2338 (errcode(ERRCODE_TOO_MANY_CONNECTIONS), 2339 errmsg("sorry, too many clients already"))); 2340 break; 2341 case CAC_SUPERUSER: 2342 /* OK for now, will check in InitPostgres */ 2343 break; 2344 case CAC_OK: 2345 break; 2346 } 2347 2348 return STATUS_OK; 2349 } 2350 2351 /* 2352 * Send a NegotiateProtocolVersion to the client. This lets the client know 2353 * that they have requested a newer minor protocol version than we are able 2354 * to speak. We'll speak the highest version we know about; the client can, 2355 * of course, abandon the connection if that's a problem. 2356 * 2357 * We also include in the response a list of protocol options we didn't 2358 * understand. This allows clients to include optional parameters that might 2359 * be present either in newer protocol versions or third-party protocol 2360 * extensions without fear of having to reconnect if those options are not 2361 * understood, while at the same time making certain that the client is aware 2362 * of which options were actually accepted. 2363 */ 2364 static void 2365 SendNegotiateProtocolVersion(List *unrecognized_protocol_options) 2366 { 2367 StringInfoData buf; 2368 ListCell *lc; 2369 2370 pq_beginmessage(&buf, 'v'); /* NegotiateProtocolVersion */ 2371 pq_sendint32(&buf, PG_PROTOCOL_LATEST); 2372 pq_sendint32(&buf, list_length(unrecognized_protocol_options)); 2373 foreach(lc, unrecognized_protocol_options) 2374 pq_sendstring(&buf, lfirst(lc)); 2375 pq_endmessage(&buf); 2376 2377 /* no need to flush, some other message will follow */ 2378 } 2379 2380 /* 2381 * The client has sent a cancel request packet, not a normal 2382 * start-a-new-connection packet. Perform the necessary processing. 2383 * Nothing is sent back to the client. 2384 */ 2385 static void 2386 processCancelRequest(Port *port, void *pkt) 2387 { 2388 CancelRequestPacket *canc = (CancelRequestPacket *) pkt; 2389 int backendPID; 2390 int32 cancelAuthCode; 2391 Backend *bp; 2392 2393 #ifndef EXEC_BACKEND 2394 dlist_iter iter; 2395 #else 2396 int i; 2397 #endif 2398 2399 backendPID = (int) pg_ntoh32(canc->backendPID); 2400 cancelAuthCode = (int32) pg_ntoh32(canc->cancelAuthCode); 2401 2402 /* 2403 * See if we have a matching backend. In the EXEC_BACKEND case, we can no 2404 * longer access the postmaster's own backend list, and must rely on the 2405 * duplicate array in shared memory. 2406 */ 2407 #ifndef EXEC_BACKEND 2408 dlist_foreach(iter, &BackendList) 2409 { 2410 bp = dlist_container(Backend, elem, iter.cur); 2411 #else 2412 for (i = MaxLivePostmasterChildren() - 1; i >= 0; i--) 2413 { 2414 bp = (Backend *) &ShmemBackendArray[i]; 2415 #endif 2416 if (bp->pid == backendPID) 2417 { 2418 if (bp->cancel_key == cancelAuthCode) 2419 { 2420 /* Found a match; signal that backend to cancel current op */ 2421 ereport(DEBUG2, 2422 (errmsg_internal("processing cancel request: sending SIGINT to process %d", 2423 backendPID))); 2424 signal_child(bp->pid, SIGINT); 2425 } 2426 else 2427 /* Right PID, wrong key: no way, Jose */ 2428 ereport(LOG, 2429 (errmsg("wrong key in cancel request for process %d", 2430 backendPID))); 2431 return; 2432 } 2433 #ifndef EXEC_BACKEND /* make GNU Emacs 26.1 see brace balance */ 2434 } 2435 #else 2436 } 2437 #endif 2438 2439 /* No matching backend */ 2440 ereport(LOG, 2441 (errmsg("PID %d in cancel request did not match any process", 2442 backendPID))); 2443 } 2444 2445 /* 2446 * canAcceptConnections --- check to see if database state allows connections 2447 * of the specified type. backend_type can be BACKEND_TYPE_NORMAL, 2448 * BACKEND_TYPE_AUTOVAC, or BACKEND_TYPE_BGWORKER. (Note that we don't yet 2449 * know whether a NORMAL connection might turn into a walsender.) 2450 */ 2451 static CAC_state 2452 canAcceptConnections(int backend_type) 2453 { 2454 CAC_state result = CAC_OK; 2455 2456 /* 2457 * Can't start backends when in startup/shutdown/inconsistent recovery 2458 * state. We treat autovac workers the same as user backends for this 2459 * purpose. However, bgworkers are excluded from this test; we expect 2460 * bgworker_should_start_now() decided whether the DB state allows them. 2461 */ 2462 if (pmState != PM_RUN && pmState != PM_HOT_STANDBY && 2463 backend_type != BACKEND_TYPE_BGWORKER) 2464 { 2465 if (Shutdown > NoShutdown) 2466 return CAC_SHUTDOWN; /* shutdown is pending */ 2467 else if (!FatalError && 2468 (pmState == PM_STARTUP || 2469 pmState == PM_RECOVERY)) 2470 return CAC_STARTUP; /* normal startup */ 2471 else 2472 return CAC_RECOVERY; /* else must be crash recovery */ 2473 } 2474 2475 /* 2476 * "Smart shutdown" restrictions are applied only to normal connections, 2477 * not to autovac workers or bgworkers. When only superusers can connect, 2478 * we return CAC_SUPERUSER to indicate that superuserness must be checked 2479 * later. Note that neither CAC_OK nor CAC_SUPERUSER can safely be 2480 * returned until we have checked for too many children. 2481 */ 2482 if (connsAllowed != ALLOW_ALL_CONNS && 2483 backend_type == BACKEND_TYPE_NORMAL) 2484 { 2485 if (connsAllowed == ALLOW_SUPERUSER_CONNS) 2486 result = CAC_SUPERUSER; /* allow superusers only */ 2487 else 2488 return CAC_SHUTDOWN; /* shutdown is pending */ 2489 } 2490 2491 /* 2492 * Don't start too many children. 2493 * 2494 * We allow more connections here than we can have backends because some 2495 * might still be authenticating; they might fail auth, or some existing 2496 * backend might exit before the auth cycle is completed. The exact 2497 * MaxBackends limit is enforced when a new backend tries to join the 2498 * shared-inval backend array. 2499 * 2500 * The limit here must match the sizes of the per-child-process arrays; 2501 * see comments for MaxLivePostmasterChildren(). 2502 */ 2503 if (CountChildren(BACKEND_TYPE_ALL) >= MaxLivePostmasterChildren()) 2504 result = CAC_TOOMANY; 2505 2506 return result; 2507 } 2508 2509 2510 /* 2511 * ConnCreate -- create a local connection data structure 2512 * 2513 * Returns NULL on failure, other than out-of-memory which is fatal. 2514 */ 2515 static Port * 2516 ConnCreate(int serverFd) 2517 { 2518 Port *port; 2519 2520 if (!(port = (Port *) calloc(1, sizeof(Port)))) 2521 { 2522 ereport(LOG, 2523 (errcode(ERRCODE_OUT_OF_MEMORY), 2524 errmsg("out of memory"))); 2525 ExitPostmaster(1); 2526 } 2527 2528 if (StreamConnection(serverFd, port) != STATUS_OK) 2529 { 2530 if (port->sock != PGINVALID_SOCKET) 2531 StreamClose(port->sock); 2532 ConnFree(port); 2533 return NULL; 2534 } 2535 2536 return port; 2537 } 2538 2539 2540 /* 2541 * ConnFree -- free a local connection data structure 2542 * 2543 * Caller has already closed the socket if any, so there's not much 2544 * to do here. 2545 */ 2546 static void 2547 ConnFree(Port *conn) 2548 { 2549 free(conn); 2550 } 2551 2552 2553 /* 2554 * ClosePostmasterPorts -- close all the postmaster's open sockets 2555 * 2556 * This is called during child process startup to release file descriptors 2557 * that are not needed by that child process. The postmaster still has 2558 * them open, of course. 2559 * 2560 * Note: we pass am_syslogger as a boolean because we don't want to set 2561 * the global variable yet when this is called. 2562 */ 2563 void 2564 ClosePostmasterPorts(bool am_syslogger) 2565 { 2566 int i; 2567 2568 #ifndef WIN32 2569 2570 /* 2571 * Close the write end of postmaster death watch pipe. It's important to 2572 * do this as early as possible, so that if postmaster dies, others won't 2573 * think that it's still running because we're holding the pipe open. 2574 */ 2575 if (close(postmaster_alive_fds[POSTMASTER_FD_OWN])) 2576 ereport(FATAL, 2577 (errcode_for_file_access(), 2578 errmsg_internal("could not close postmaster death monitoring pipe in child process: %m"))); 2579 postmaster_alive_fds[POSTMASTER_FD_OWN] = -1; 2580 #endif 2581 2582 /* Close the listen sockets */ 2583 for (i = 0; i < MAXLISTEN; i++) 2584 { 2585 if (ListenSocket[i] != PGINVALID_SOCKET) 2586 { 2587 StreamClose(ListenSocket[i]); 2588 ListenSocket[i] = PGINVALID_SOCKET; 2589 } 2590 } 2591 2592 /* If using syslogger, close the read side of the pipe */ 2593 if (!am_syslogger) 2594 { 2595 #ifndef WIN32 2596 if (syslogPipe[0] >= 0) 2597 close(syslogPipe[0]); 2598 syslogPipe[0] = -1; 2599 #else 2600 if (syslogPipe[0]) 2601 CloseHandle(syslogPipe[0]); 2602 syslogPipe[0] = 0; 2603 #endif 2604 } 2605 2606 #ifdef USE_BONJOUR 2607 /* If using Bonjour, close the connection to the mDNS daemon */ 2608 if (bonjour_sdref) 2609 close(DNSServiceRefSockFD(bonjour_sdref)); 2610 #endif 2611 } 2612 2613 2614 /* 2615 * InitProcessGlobals -- set MyProcPid, MyStartTime[stamp], random seeds 2616 * 2617 * Called early in the postmaster and every backend. 2618 */ 2619 void 2620 InitProcessGlobals(void) 2621 { 2622 unsigned int rseed; 2623 2624 MyProcPid = getpid(); 2625 MyStartTimestamp = GetCurrentTimestamp(); 2626 MyStartTime = timestamptz_to_time_t(MyStartTimestamp); 2627 2628 /* 2629 * Set a different seed for random() in every process. We want something 2630 * unpredictable, so if possible, use high-quality random bits for the 2631 * seed. Otherwise, fall back to a seed based on timestamp and PID. 2632 */ 2633 if (!pg_strong_random(&rseed, sizeof(rseed))) 2634 { 2635 /* 2636 * Since PIDs and timestamps tend to change more frequently in their 2637 * least significant bits, shift the timestamp left to allow a larger 2638 * total number of seeds in a given time period. Since that would 2639 * leave only 20 bits of the timestamp that cycle every ~1 second, 2640 * also mix in some higher bits. 2641 */ 2642 rseed = ((uint64) MyProcPid) ^ 2643 ((uint64) MyStartTimestamp << 12) ^ 2644 ((uint64) MyStartTimestamp >> 20); 2645 } 2646 srandom(rseed); 2647 } 2648 2649 2650 /* 2651 * reset_shared -- reset shared memory and semaphores 2652 */ 2653 static void 2654 reset_shared(int port) 2655 { 2656 /* 2657 * Create or re-create shared memory and semaphores. 2658 * 2659 * Note: in each "cycle of life" we will normally assign the same IPC keys 2660 * (if using SysV shmem and/or semas), since the port number is used to 2661 * determine IPC keys. This helps ensure that we will clean up dead IPC 2662 * objects if the postmaster crashes and is restarted. 2663 */ 2664 CreateSharedMemoryAndSemaphores(port); 2665 } 2666 2667 2668 /* 2669 * SIGHUP -- reread config files, and tell children to do same 2670 */ 2671 static void 2672 SIGHUP_handler(SIGNAL_ARGS) 2673 { 2674 int save_errno = errno; 2675 2676 /* 2677 * We rely on the signal mechanism to have blocked all signals ... except 2678 * on Windows, which lacks sigaction(), so we have to do it manually. 2679 */ 2680 #ifdef WIN32 2681 PG_SETMASK(&BlockSig); 2682 #endif 2683 2684 if (Shutdown <= SmartShutdown) 2685 { 2686 ereport(LOG, 2687 (errmsg("received SIGHUP, reloading configuration files"))); 2688 ProcessConfigFile(PGC_SIGHUP); 2689 SignalChildren(SIGHUP); 2690 if (StartupPID != 0) 2691 signal_child(StartupPID, SIGHUP); 2692 if (BgWriterPID != 0) 2693 signal_child(BgWriterPID, SIGHUP); 2694 if (CheckpointerPID != 0) 2695 signal_child(CheckpointerPID, SIGHUP); 2696 if (WalWriterPID != 0) 2697 signal_child(WalWriterPID, SIGHUP); 2698 if (WalReceiverPID != 0) 2699 signal_child(WalReceiverPID, SIGHUP); 2700 if (AutoVacPID != 0) 2701 signal_child(AutoVacPID, SIGHUP); 2702 if (PgArchPID != 0) 2703 signal_child(PgArchPID, SIGHUP); 2704 if (SysLoggerPID != 0) 2705 signal_child(SysLoggerPID, SIGHUP); 2706 if (PgStatPID != 0) 2707 signal_child(PgStatPID, SIGHUP); 2708 2709 /* Reload authentication config files too */ 2710 if (!load_hba()) 2711 ereport(LOG, 2712 /* translator: %s is a configuration file */ 2713 (errmsg("%s was not reloaded", "pg_hba.conf"))); 2714 2715 if (!load_ident()) 2716 ereport(LOG, 2717 (errmsg("%s was not reloaded", "pg_ident.conf"))); 2718 2719 #ifdef USE_SSL 2720 /* Reload SSL configuration as well */ 2721 if (EnableSSL) 2722 { 2723 if (secure_initialize(false) == 0) 2724 LoadedSSL = true; 2725 else 2726 ereport(LOG, 2727 (errmsg("SSL configuration was not reloaded"))); 2728 } 2729 else 2730 { 2731 secure_destroy(); 2732 LoadedSSL = false; 2733 } 2734 #endif 2735 2736 #ifdef EXEC_BACKEND 2737 /* Update the starting-point file for future children */ 2738 write_nondefault_variables(PGC_SIGHUP); 2739 #endif 2740 } 2741 2742 #ifdef WIN32 2743 PG_SETMASK(&UnBlockSig); 2744 #endif 2745 2746 errno = save_errno; 2747 } 2748 2749 2750 /* 2751 * pmdie -- signal handler for processing various postmaster signals. 2752 */ 2753 static void 2754 pmdie(SIGNAL_ARGS) 2755 { 2756 int save_errno = errno; 2757 2758 /* 2759 * We rely on the signal mechanism to have blocked all signals ... except 2760 * on Windows, which lacks sigaction(), so we have to do it manually. 2761 */ 2762 #ifdef WIN32 2763 PG_SETMASK(&BlockSig); 2764 #endif 2765 2766 ereport(DEBUG2, 2767 (errmsg_internal("postmaster received signal %d", 2768 postgres_signal_arg))); 2769 2770 switch (postgres_signal_arg) 2771 { 2772 case SIGTERM: 2773 2774 /* 2775 * Smart Shutdown: 2776 * 2777 * Wait for children to end their work, then shut down. 2778 */ 2779 if (Shutdown >= SmartShutdown) 2780 break; 2781 Shutdown = SmartShutdown; 2782 ereport(LOG, 2783 (errmsg("received smart shutdown request"))); 2784 2785 /* Report status */ 2786 AddToDataDirLockFile(LOCK_FILE_LINE_PM_STATUS, PM_STATUS_STOPPING); 2787 #ifdef USE_SYSTEMD 2788 sd_notify(0, "STOPPING=1"); 2789 #endif 2790 2791 /* 2792 * If we reached normal running, we have to wait for any online 2793 * backup mode to end; otherwise go straight to waiting for client 2794 * backends to exit. (The difference is that in the former state, 2795 * we'll still let in new superuser clients, so that somebody can 2796 * end the online backup mode.) If already in PM_STOP_BACKENDS or 2797 * a later state, do not change it. 2798 */ 2799 if (pmState == PM_RUN) 2800 connsAllowed = ALLOW_SUPERUSER_CONNS; 2801 else if (pmState == PM_HOT_STANDBY) 2802 connsAllowed = ALLOW_NO_CONNS; 2803 else if (pmState == PM_STARTUP || pmState == PM_RECOVERY) 2804 { 2805 /* There should be no clients, so proceed to stop children */ 2806 pmState = PM_STOP_BACKENDS; 2807 } 2808 2809 /* 2810 * Now wait for online backup mode to end and backends to exit. If 2811 * that is already the case, PostmasterStateMachine will take the 2812 * next step. 2813 */ 2814 PostmasterStateMachine(); 2815 break; 2816 2817 case SIGINT: 2818 2819 /* 2820 * Fast Shutdown: 2821 * 2822 * Abort all children with SIGTERM (rollback active transactions 2823 * and exit) and shut down when they are gone. 2824 */ 2825 if (Shutdown >= FastShutdown) 2826 break; 2827 Shutdown = FastShutdown; 2828 ereport(LOG, 2829 (errmsg("received fast shutdown request"))); 2830 2831 /* Report status */ 2832 AddToDataDirLockFile(LOCK_FILE_LINE_PM_STATUS, PM_STATUS_STOPPING); 2833 #ifdef USE_SYSTEMD 2834 sd_notify(0, "STOPPING=1"); 2835 #endif 2836 2837 if (pmState == PM_STARTUP || pmState == PM_RECOVERY) 2838 { 2839 /* Just shut down background processes silently */ 2840 pmState = PM_STOP_BACKENDS; 2841 } 2842 else if (pmState == PM_RUN || 2843 pmState == PM_HOT_STANDBY) 2844 { 2845 /* Report that we're about to zap live client sessions */ 2846 ereport(LOG, 2847 (errmsg("aborting any active transactions"))); 2848 pmState = PM_STOP_BACKENDS; 2849 } 2850 2851 /* 2852 * PostmasterStateMachine will issue any necessary signals, or 2853 * take the next step if no child processes need to be killed. 2854 */ 2855 PostmasterStateMachine(); 2856 break; 2857 2858 case SIGQUIT: 2859 2860 /* 2861 * Immediate Shutdown: 2862 * 2863 * abort all children with SIGQUIT, wait for them to exit, 2864 * terminate remaining ones with SIGKILL, then exit without 2865 * attempt to properly shut down the data base system. 2866 */ 2867 if (Shutdown >= ImmediateShutdown) 2868 break; 2869 Shutdown = ImmediateShutdown; 2870 ereport(LOG, 2871 (errmsg("received immediate shutdown request"))); 2872 2873 /* Report status */ 2874 AddToDataDirLockFile(LOCK_FILE_LINE_PM_STATUS, PM_STATUS_STOPPING); 2875 #ifdef USE_SYSTEMD 2876 sd_notify(0, "STOPPING=1"); 2877 #endif 2878 2879 TerminateChildren(SIGQUIT); 2880 pmState = PM_WAIT_BACKENDS; 2881 2882 /* set stopwatch for them to die */ 2883 AbortStartTime = time(NULL); 2884 2885 /* 2886 * Now wait for backends to exit. If there are none, 2887 * PostmasterStateMachine will take the next step. 2888 */ 2889 PostmasterStateMachine(); 2890 break; 2891 } 2892 2893 #ifdef WIN32 2894 PG_SETMASK(&UnBlockSig); 2895 #endif 2896 2897 errno = save_errno; 2898 } 2899 2900 /* 2901 * Reaper -- signal handler to cleanup after a child process dies. 2902 */ 2903 static void 2904 reaper(SIGNAL_ARGS) 2905 { 2906 int save_errno = errno; 2907 int pid; /* process id of dead child process */ 2908 int exitstatus; /* its exit status */ 2909 2910 /* 2911 * We rely on the signal mechanism to have blocked all signals ... except 2912 * on Windows, which lacks sigaction(), so we have to do it manually. 2913 */ 2914 #ifdef WIN32 2915 PG_SETMASK(&BlockSig); 2916 #endif 2917 2918 ereport(DEBUG4, 2919 (errmsg_internal("reaping dead processes"))); 2920 2921 while ((pid = waitpid(-1, &exitstatus, WNOHANG)) > 0) 2922 { 2923 /* 2924 * Check if this child was a startup process. 2925 */ 2926 if (pid == StartupPID) 2927 { 2928 StartupPID = 0; 2929 2930 /* 2931 * Startup process exited in response to a shutdown request (or it 2932 * completed normally regardless of the shutdown request). 2933 */ 2934 if (Shutdown > NoShutdown && 2935 (EXIT_STATUS_0(exitstatus) || EXIT_STATUS_1(exitstatus))) 2936 { 2937 StartupStatus = STARTUP_NOT_RUNNING; 2938 pmState = PM_WAIT_BACKENDS; 2939 /* PostmasterStateMachine logic does the rest */ 2940 continue; 2941 } 2942 2943 if (EXIT_STATUS_3(exitstatus)) 2944 { 2945 ereport(LOG, 2946 (errmsg("shutdown at recovery target"))); 2947 StartupStatus = STARTUP_NOT_RUNNING; 2948 Shutdown = Max(Shutdown, SmartShutdown); 2949 TerminateChildren(SIGTERM); 2950 pmState = PM_WAIT_BACKENDS; 2951 /* PostmasterStateMachine logic does the rest */ 2952 continue; 2953 } 2954 2955 /* 2956 * Unexpected exit of startup process (including FATAL exit) 2957 * during PM_STARTUP is treated as catastrophic. There are no 2958 * other processes running yet, so we can just exit. 2959 */ 2960 if (pmState == PM_STARTUP && !EXIT_STATUS_0(exitstatus)) 2961 { 2962 LogChildExit(LOG, _("startup process"), 2963 pid, exitstatus); 2964 ereport(LOG, 2965 (errmsg("aborting startup due to startup process failure"))); 2966 ExitPostmaster(1); 2967 } 2968 2969 /* 2970 * After PM_STARTUP, any unexpected exit (including FATAL exit) of 2971 * the startup process is catastrophic, so kill other children, 2972 * and set StartupStatus so we don't try to reinitialize after 2973 * they're gone. Exception: if StartupStatus is STARTUP_SIGNALED, 2974 * then we previously sent the startup process a SIGQUIT; so 2975 * that's probably the reason it died, and we do want to try to 2976 * restart in that case. 2977 */ 2978 if (!EXIT_STATUS_0(exitstatus)) 2979 { 2980 if (StartupStatus == STARTUP_SIGNALED) 2981 StartupStatus = STARTUP_NOT_RUNNING; 2982 else 2983 StartupStatus = STARTUP_CRASHED; 2984 HandleChildCrash(pid, exitstatus, 2985 _("startup process")); 2986 continue; 2987 } 2988 2989 /* 2990 * Startup succeeded, commence normal operations 2991 */ 2992 StartupStatus = STARTUP_NOT_RUNNING; 2993 FatalError = false; 2994 Assert(AbortStartTime == 0); 2995 ReachedNormalRunning = true; 2996 pmState = PM_RUN; 2997 connsAllowed = ALLOW_ALL_CONNS; 2998 2999 /* 3000 * Crank up the background tasks, if we didn't do that already 3001 * when we entered consistent recovery state. It doesn't matter 3002 * if this fails, we'll just try again later. 3003 */ 3004 if (CheckpointerPID == 0) 3005 CheckpointerPID = StartCheckpointer(); 3006 if (BgWriterPID == 0) 3007 BgWriterPID = StartBackgroundWriter(); 3008 if (WalWriterPID == 0) 3009 WalWriterPID = StartWalWriter(); 3010 3011 /* 3012 * Likewise, start other special children as needed. In a restart 3013 * situation, some of them may be alive already. 3014 */ 3015 if (!IsBinaryUpgrade && AutoVacuumingActive() && AutoVacPID == 0) 3016 AutoVacPID = StartAutoVacLauncher(); 3017 if (PgArchStartupAllowed() && PgArchPID == 0) 3018 PgArchPID = pgarch_start(); 3019 if (PgStatPID == 0) 3020 PgStatPID = pgstat_start(); 3021 3022 /* workers may be scheduled to start now */ 3023 maybe_start_bgworkers(); 3024 3025 /* at this point we are really open for business */ 3026 ereport(LOG, 3027 (errmsg("database system is ready to accept connections"))); 3028 3029 /* Report status */ 3030 AddToDataDirLockFile(LOCK_FILE_LINE_PM_STATUS, PM_STATUS_READY); 3031 #ifdef USE_SYSTEMD 3032 sd_notify(0, "READY=1"); 3033 #endif 3034 3035 continue; 3036 } 3037 3038 /* 3039 * Was it the bgwriter? Normal exit can be ignored; we'll start a new 3040 * one at the next iteration of the postmaster's main loop, if 3041 * necessary. Any other exit condition is treated as a crash. 3042 */ 3043 if (pid == BgWriterPID) 3044 { 3045 BgWriterPID = 0; 3046 if (!EXIT_STATUS_0(exitstatus)) 3047 HandleChildCrash(pid, exitstatus, 3048 _("background writer process")); 3049 continue; 3050 } 3051 3052 /* 3053 * Was it the checkpointer? 3054 */ 3055 if (pid == CheckpointerPID) 3056 { 3057 CheckpointerPID = 0; 3058 if (EXIT_STATUS_0(exitstatus) && pmState == PM_SHUTDOWN) 3059 { 3060 /* 3061 * OK, we saw normal exit of the checkpointer after it's been 3062 * told to shut down. We expect that it wrote a shutdown 3063 * checkpoint. (If for some reason it didn't, recovery will 3064 * occur on next postmaster start.) 3065 * 3066 * At this point we should have no normal backend children 3067 * left (else we'd not be in PM_SHUTDOWN state) but we might 3068 * have dead_end children to wait for. 3069 * 3070 * If we have an archiver subprocess, tell it to do a last 3071 * archive cycle and quit. Likewise, if we have walsender 3072 * processes, tell them to send any remaining WAL and quit. 3073 */ 3074 Assert(Shutdown > NoShutdown); 3075 3076 /* Waken archiver for the last time */ 3077 if (PgArchPID != 0) 3078 signal_child(PgArchPID, SIGUSR2); 3079 3080 /* 3081 * Waken walsenders for the last time. No regular backends 3082 * should be around anymore. 3083 */ 3084 SignalChildren(SIGUSR2); 3085 3086 pmState = PM_SHUTDOWN_2; 3087 3088 /* 3089 * We can also shut down the stats collector now; there's 3090 * nothing left for it to do. 3091 */ 3092 if (PgStatPID != 0) 3093 signal_child(PgStatPID, SIGQUIT); 3094 } 3095 else 3096 { 3097 /* 3098 * Any unexpected exit of the checkpointer (including FATAL 3099 * exit) is treated as a crash. 3100 */ 3101 HandleChildCrash(pid, exitstatus, 3102 _("checkpointer process")); 3103 } 3104 3105 continue; 3106 } 3107 3108 /* 3109 * Was it the wal writer? Normal exit can be ignored; we'll start a 3110 * new one at the next iteration of the postmaster's main loop, if 3111 * necessary. Any other exit condition is treated as a crash. 3112 */ 3113 if (pid == WalWriterPID) 3114 { 3115 WalWriterPID = 0; 3116 if (!EXIT_STATUS_0(exitstatus)) 3117 HandleChildCrash(pid, exitstatus, 3118 _("WAL writer process")); 3119 continue; 3120 } 3121 3122 /* 3123 * Was it the wal receiver? If exit status is zero (normal) or one 3124 * (FATAL exit), we assume everything is all right just like normal 3125 * backends. (If we need a new wal receiver, we'll start one at the 3126 * next iteration of the postmaster's main loop.) 3127 */ 3128 if (pid == WalReceiverPID) 3129 { 3130 WalReceiverPID = 0; 3131 if (!EXIT_STATUS_0(exitstatus) && !EXIT_STATUS_1(exitstatus)) 3132 HandleChildCrash(pid, exitstatus, 3133 _("WAL receiver process")); 3134 continue; 3135 } 3136 3137 /* 3138 * Was it the autovacuum launcher? Normal exit can be ignored; we'll 3139 * start a new one at the next iteration of the postmaster's main 3140 * loop, if necessary. Any other exit condition is treated as a 3141 * crash. 3142 */ 3143 if (pid == AutoVacPID) 3144 { 3145 AutoVacPID = 0; 3146 if (!EXIT_STATUS_0(exitstatus)) 3147 HandleChildCrash(pid, exitstatus, 3148 _("autovacuum launcher process")); 3149 continue; 3150 } 3151 3152 /* 3153 * Was it the archiver? If so, just try to start a new one; no need 3154 * to force reset of the rest of the system. (If fail, we'll try 3155 * again in future cycles of the main loop.). Unless we were waiting 3156 * for it to shut down; don't restart it in that case, and 3157 * PostmasterStateMachine() will advance to the next shutdown step. 3158 */ 3159 if (pid == PgArchPID) 3160 { 3161 PgArchPID = 0; 3162 if (!EXIT_STATUS_0(exitstatus)) 3163 LogChildExit(LOG, _("archiver process"), 3164 pid, exitstatus); 3165 if (PgArchStartupAllowed()) 3166 PgArchPID = pgarch_start(); 3167 continue; 3168 } 3169 3170 /* 3171 * Was it the statistics collector? If so, just try to start a new 3172 * one; no need to force reset of the rest of the system. (If fail, 3173 * we'll try again in future cycles of the main loop.) 3174 */ 3175 if (pid == PgStatPID) 3176 { 3177 PgStatPID = 0; 3178 if (!EXIT_STATUS_0(exitstatus)) 3179 LogChildExit(LOG, _("statistics collector process"), 3180 pid, exitstatus); 3181 if (pmState == PM_RUN || pmState == PM_HOT_STANDBY) 3182 PgStatPID = pgstat_start(); 3183 continue; 3184 } 3185 3186 /* Was it the system logger? If so, try to start a new one */ 3187 if (pid == SysLoggerPID) 3188 { 3189 SysLoggerPID = 0; 3190 /* for safety's sake, launch new logger *first* */ 3191 SysLoggerPID = SysLogger_Start(); 3192 if (!EXIT_STATUS_0(exitstatus)) 3193 LogChildExit(LOG, _("system logger process"), 3194 pid, exitstatus); 3195 continue; 3196 } 3197 3198 /* Was it one of our background workers? */ 3199 if (CleanupBackgroundWorker(pid, exitstatus)) 3200 { 3201 /* have it be restarted */ 3202 HaveCrashedWorker = true; 3203 continue; 3204 } 3205 3206 /* 3207 * Else do standard backend child cleanup. 3208 */ 3209 CleanupBackend(pid, exitstatus); 3210 } /* loop over pending child-death reports */ 3211 3212 /* 3213 * After cleaning out the SIGCHLD queue, see if we have any state changes 3214 * or actions to make. 3215 */ 3216 PostmasterStateMachine(); 3217 3218 /* Done with signal handler */ 3219 #ifdef WIN32 3220 PG_SETMASK(&UnBlockSig); 3221 #endif 3222 3223 errno = save_errno; 3224 } 3225 3226 /* 3227 * Scan the bgworkers list and see if the given PID (which has just stopped 3228 * or crashed) is in it. Handle its shutdown if so, and return true. If not a 3229 * bgworker, return false. 3230 * 3231 * This is heavily based on CleanupBackend. One important difference is that 3232 * we don't know yet that the dying process is a bgworker, so we must be silent 3233 * until we're sure it is. 3234 */ 3235 static bool 3236 CleanupBackgroundWorker(int pid, 3237 int exitstatus) /* child's exit status */ 3238 { 3239 char namebuf[MAXPGPATH]; 3240 slist_mutable_iter iter; 3241 3242 slist_foreach_modify(iter, &BackgroundWorkerList) 3243 { 3244 RegisteredBgWorker *rw; 3245 3246 rw = slist_container(RegisteredBgWorker, rw_lnode, iter.cur); 3247 3248 if (rw->rw_pid != pid) 3249 continue; 3250 3251 #ifdef WIN32 3252 /* see CleanupBackend */ 3253 if (exitstatus == ERROR_WAIT_NO_CHILDREN) 3254 exitstatus = 0; 3255 #endif 3256 3257 snprintf(namebuf, MAXPGPATH, _("background worker \"%s\""), 3258 rw->rw_worker.bgw_type); 3259 3260 3261 if (!EXIT_STATUS_0(exitstatus)) 3262 { 3263 /* Record timestamp, so we know when to restart the worker. */ 3264 rw->rw_crashed_at = GetCurrentTimestamp(); 3265 } 3266 else 3267 { 3268 /* Zero exit status means terminate */ 3269 rw->rw_crashed_at = 0; 3270 rw->rw_terminate = true; 3271 } 3272 3273 /* 3274 * Additionally, for shared-memory-connected workers, just like a 3275 * backend, any exit status other than 0 or 1 is considered a crash 3276 * and causes a system-wide restart. 3277 */ 3278 if ((rw->rw_worker.bgw_flags & BGWORKER_SHMEM_ACCESS) != 0) 3279 { 3280 if (!EXIT_STATUS_0(exitstatus) && !EXIT_STATUS_1(exitstatus)) 3281 { 3282 HandleChildCrash(pid, exitstatus, namebuf); 3283 return true; 3284 } 3285 } 3286 3287 /* 3288 * We must release the postmaster child slot whether this worker is 3289 * connected to shared memory or not, but we only treat it as a crash 3290 * if it is in fact connected. 3291 */ 3292 if (!ReleasePostmasterChildSlot(rw->rw_child_slot) && 3293 (rw->rw_worker.bgw_flags & BGWORKER_SHMEM_ACCESS) != 0) 3294 { 3295 HandleChildCrash(pid, exitstatus, namebuf); 3296 return true; 3297 } 3298 3299 /* Get it out of the BackendList and clear out remaining data */ 3300 dlist_delete(&rw->rw_backend->elem); 3301 #ifdef EXEC_BACKEND 3302 ShmemBackendArrayRemove(rw->rw_backend); 3303 #endif 3304 3305 /* 3306 * It's possible that this background worker started some OTHER 3307 * background worker and asked to be notified when that worker started 3308 * or stopped. If so, cancel any notifications destined for the 3309 * now-dead backend. 3310 */ 3311 if (rw->rw_backend->bgworker_notify) 3312 BackgroundWorkerStopNotifications(rw->rw_pid); 3313 free(rw->rw_backend); 3314 rw->rw_backend = NULL; 3315 rw->rw_pid = 0; 3316 rw->rw_child_slot = 0; 3317 ReportBackgroundWorkerExit(&iter); /* report child death */ 3318 3319 LogChildExit(EXIT_STATUS_0(exitstatus) ? DEBUG1 : LOG, 3320 namebuf, pid, exitstatus); 3321 3322 return true; 3323 } 3324 3325 return false; 3326 } 3327 3328 /* 3329 * CleanupBackend -- cleanup after terminated backend. 3330 * 3331 * Remove all local state associated with backend. 3332 * 3333 * If you change this, see also CleanupBackgroundWorker. 3334 */ 3335 static void 3336 CleanupBackend(int pid, 3337 int exitstatus) /* child's exit status. */ 3338 { 3339 dlist_mutable_iter iter; 3340 3341 LogChildExit(DEBUG2, _("server process"), pid, exitstatus); 3342 3343 /* 3344 * If a backend dies in an ugly way then we must signal all other backends 3345 * to quickdie. If exit status is zero (normal) or one (FATAL exit), we 3346 * assume everything is all right and proceed to remove the backend from 3347 * the active backend list. 3348 */ 3349 3350 #ifdef WIN32 3351 3352 /* 3353 * On win32, also treat ERROR_WAIT_NO_CHILDREN (128) as nonfatal case, 3354 * since that sometimes happens under load when the process fails to start 3355 * properly (long before it starts using shared memory). Microsoft reports 3356 * it is related to mutex failure: 3357 * http://archives.postgresql.org/pgsql-hackers/2010-09/msg00790.php 3358 */ 3359 if (exitstatus == ERROR_WAIT_NO_CHILDREN) 3360 { 3361 LogChildExit(LOG, _("server process"), pid, exitstatus); 3362 exitstatus = 0; 3363 } 3364 #endif 3365 3366 if (!EXIT_STATUS_0(exitstatus) && !EXIT_STATUS_1(exitstatus)) 3367 { 3368 HandleChildCrash(pid, exitstatus, _("server process")); 3369 return; 3370 } 3371 3372 dlist_foreach_modify(iter, &BackendList) 3373 { 3374 Backend *bp = dlist_container(Backend, elem, iter.cur); 3375 3376 if (bp->pid == pid) 3377 { 3378 if (!bp->dead_end) 3379 { 3380 if (!ReleasePostmasterChildSlot(bp->child_slot)) 3381 { 3382 /* 3383 * Uh-oh, the child failed to clean itself up. Treat as a 3384 * crash after all. 3385 */ 3386 HandleChildCrash(pid, exitstatus, _("server process")); 3387 return; 3388 } 3389 #ifdef EXEC_BACKEND 3390 ShmemBackendArrayRemove(bp); 3391 #endif 3392 } 3393 if (bp->bgworker_notify) 3394 { 3395 /* 3396 * This backend may have been slated to receive SIGUSR1 when 3397 * some background worker started or stopped. Cancel those 3398 * notifications, as we don't want to signal PIDs that are not 3399 * PostgreSQL backends. This gets skipped in the (probably 3400 * very common) case where the backend has never requested any 3401 * such notifications. 3402 */ 3403 BackgroundWorkerStopNotifications(bp->pid); 3404 } 3405 dlist_delete(iter.cur); 3406 free(bp); 3407 break; 3408 } 3409 } 3410 } 3411 3412 /* 3413 * HandleChildCrash -- cleanup after failed backend, bgwriter, checkpointer, 3414 * walwriter, autovacuum, or background worker. 3415 * 3416 * The objectives here are to clean up our local state about the child 3417 * process, and to signal all other remaining children to quickdie. 3418 */ 3419 static void 3420 HandleChildCrash(int pid, int exitstatus, const char *procname) 3421 { 3422 dlist_mutable_iter iter; 3423 slist_iter siter; 3424 Backend *bp; 3425 bool take_action; 3426 3427 /* 3428 * We only log messages and send signals if this is the first process 3429 * crash and we're not doing an immediate shutdown; otherwise, we're only 3430 * here to update postmaster's idea of live processes. If we have already 3431 * signalled children, nonzero exit status is to be expected, so don't 3432 * clutter log. 3433 */ 3434 take_action = !FatalError && Shutdown != ImmediateShutdown; 3435 3436 if (take_action) 3437 { 3438 LogChildExit(LOG, procname, pid, exitstatus); 3439 ereport(LOG, 3440 (errmsg("terminating any other active server processes"))); 3441 } 3442 3443 /* Process background workers. */ 3444 slist_foreach(siter, &BackgroundWorkerList) 3445 { 3446 RegisteredBgWorker *rw; 3447 3448 rw = slist_container(RegisteredBgWorker, rw_lnode, siter.cur); 3449 if (rw->rw_pid == 0) 3450 continue; /* not running */ 3451 if (rw->rw_pid == pid) 3452 { 3453 /* 3454 * Found entry for freshly-dead worker, so remove it. 3455 */ 3456 (void) ReleasePostmasterChildSlot(rw->rw_child_slot); 3457 dlist_delete(&rw->rw_backend->elem); 3458 #ifdef EXEC_BACKEND 3459 ShmemBackendArrayRemove(rw->rw_backend); 3460 #endif 3461 free(rw->rw_backend); 3462 rw->rw_backend = NULL; 3463 rw->rw_pid = 0; 3464 rw->rw_child_slot = 0; 3465 /* don't reset crashed_at */ 3466 /* don't report child stop, either */ 3467 /* Keep looping so we can signal remaining workers */ 3468 } 3469 else 3470 { 3471 /* 3472 * This worker is still alive. Unless we did so already, tell it 3473 * to commit hara-kiri. 3474 * 3475 * SIGQUIT is the special signal that says exit without proc_exit 3476 * and let the user know what's going on. But if SendStop is set 3477 * (-s on command line), then we send SIGSTOP instead, so that we 3478 * can get core dumps from all backends by hand. 3479 */ 3480 if (take_action) 3481 { 3482 ereport(DEBUG2, 3483 (errmsg_internal("sending %s to process %d", 3484 (SendStop ? "SIGSTOP" : "SIGQUIT"), 3485 (int) rw->rw_pid))); 3486 signal_child(rw->rw_pid, (SendStop ? SIGSTOP : SIGQUIT)); 3487 } 3488 } 3489 } 3490 3491 /* Process regular backends */ 3492 dlist_foreach_modify(iter, &BackendList) 3493 { 3494 bp = dlist_container(Backend, elem, iter.cur); 3495 3496 if (bp->pid == pid) 3497 { 3498 /* 3499 * Found entry for freshly-dead backend, so remove it. 3500 */ 3501 if (!bp->dead_end) 3502 { 3503 (void) ReleasePostmasterChildSlot(bp->child_slot); 3504 #ifdef EXEC_BACKEND 3505 ShmemBackendArrayRemove(bp); 3506 #endif 3507 } 3508 dlist_delete(iter.cur); 3509 free(bp); 3510 /* Keep looping so we can signal remaining backends */ 3511 } 3512 else 3513 { 3514 /* 3515 * This backend is still alive. Unless we did so already, tell it 3516 * to commit hara-kiri. 3517 * 3518 * SIGQUIT is the special signal that says exit without proc_exit 3519 * and let the user know what's going on. But if SendStop is set 3520 * (-s on command line), then we send SIGSTOP instead, so that we 3521 * can get core dumps from all backends by hand. 3522 * 3523 * We could exclude dead_end children here, but at least in the 3524 * SIGSTOP case it seems better to include them. 3525 * 3526 * Background workers were already processed above; ignore them 3527 * here. 3528 */ 3529 if (bp->bkend_type == BACKEND_TYPE_BGWORKER) 3530 continue; 3531 3532 if (take_action) 3533 { 3534 ereport(DEBUG2, 3535 (errmsg_internal("sending %s to process %d", 3536 (SendStop ? "SIGSTOP" : "SIGQUIT"), 3537 (int) bp->pid))); 3538 signal_child(bp->pid, (SendStop ? SIGSTOP : SIGQUIT)); 3539 } 3540 } 3541 } 3542 3543 /* Take care of the startup process too */ 3544 if (pid == StartupPID) 3545 { 3546 StartupPID = 0; 3547 StartupStatus = STARTUP_CRASHED; 3548 } 3549 else if (StartupPID != 0 && take_action) 3550 { 3551 ereport(DEBUG2, 3552 (errmsg_internal("sending %s to process %d", 3553 (SendStop ? "SIGSTOP" : "SIGQUIT"), 3554 (int) StartupPID))); 3555 signal_child(StartupPID, (SendStop ? SIGSTOP : SIGQUIT)); 3556 StartupStatus = STARTUP_SIGNALED; 3557 } 3558 3559 /* Take care of the bgwriter too */ 3560 if (pid == BgWriterPID) 3561 BgWriterPID = 0; 3562 else if (BgWriterPID != 0 && take_action) 3563 { 3564 ereport(DEBUG2, 3565 (errmsg_internal("sending %s to process %d", 3566 (SendStop ? "SIGSTOP" : "SIGQUIT"), 3567 (int) BgWriterPID))); 3568 signal_child(BgWriterPID, (SendStop ? SIGSTOP : SIGQUIT)); 3569 } 3570 3571 /* Take care of the checkpointer too */ 3572 if (pid == CheckpointerPID) 3573 CheckpointerPID = 0; 3574 else if (CheckpointerPID != 0 && take_action) 3575 { 3576 ereport(DEBUG2, 3577 (errmsg_internal("sending %s to process %d", 3578 (SendStop ? "SIGSTOP" : "SIGQUIT"), 3579 (int) CheckpointerPID))); 3580 signal_child(CheckpointerPID, (SendStop ? SIGSTOP : SIGQUIT)); 3581 } 3582 3583 /* Take care of the walwriter too */ 3584 if (pid == WalWriterPID) 3585 WalWriterPID = 0; 3586 else if (WalWriterPID != 0 && take_action) 3587 { 3588 ereport(DEBUG2, 3589 (errmsg_internal("sending %s to process %d", 3590 (SendStop ? "SIGSTOP" : "SIGQUIT"), 3591 (int) WalWriterPID))); 3592 signal_child(WalWriterPID, (SendStop ? SIGSTOP : SIGQUIT)); 3593 } 3594 3595 /* Take care of the walreceiver too */ 3596 if (pid == WalReceiverPID) 3597 WalReceiverPID = 0; 3598 else if (WalReceiverPID != 0 && take_action) 3599 { 3600 ereport(DEBUG2, 3601 (errmsg_internal("sending %s to process %d", 3602 (SendStop ? "SIGSTOP" : "SIGQUIT"), 3603 (int) WalReceiverPID))); 3604 signal_child(WalReceiverPID, (SendStop ? SIGSTOP : SIGQUIT)); 3605 } 3606 3607 /* Take care of the autovacuum launcher too */ 3608 if (pid == AutoVacPID) 3609 AutoVacPID = 0; 3610 else if (AutoVacPID != 0 && take_action) 3611 { 3612 ereport(DEBUG2, 3613 (errmsg_internal("sending %s to process %d", 3614 (SendStop ? "SIGSTOP" : "SIGQUIT"), 3615 (int) AutoVacPID))); 3616 signal_child(AutoVacPID, (SendStop ? SIGSTOP : SIGQUIT)); 3617 } 3618 3619 /* 3620 * Force a power-cycle of the pgarch process too. (This isn't absolutely 3621 * necessary, but it seems like a good idea for robustness, and it 3622 * simplifies the state-machine logic in the case where a shutdown request 3623 * arrives during crash processing.) 3624 */ 3625 if (PgArchPID != 0 && take_action) 3626 { 3627 ereport(DEBUG2, 3628 (errmsg_internal("sending %s to process %d", 3629 "SIGQUIT", 3630 (int) PgArchPID))); 3631 signal_child(PgArchPID, SIGQUIT); 3632 } 3633 3634 /* 3635 * Force a power-cycle of the pgstat process too. (This isn't absolutely 3636 * necessary, but it seems like a good idea for robustness, and it 3637 * simplifies the state-machine logic in the case where a shutdown request 3638 * arrives during crash processing.) 3639 */ 3640 if (PgStatPID != 0 && take_action) 3641 { 3642 ereport(DEBUG2, 3643 (errmsg_internal("sending %s to process %d", 3644 "SIGQUIT", 3645 (int) PgStatPID))); 3646 signal_child(PgStatPID, SIGQUIT); 3647 allow_immediate_pgstat_restart(); 3648 } 3649 3650 /* We do NOT restart the syslogger */ 3651 3652 if (Shutdown != ImmediateShutdown) 3653 FatalError = true; 3654 3655 /* We now transit into a state of waiting for children to die */ 3656 if (pmState == PM_RECOVERY || 3657 pmState == PM_HOT_STANDBY || 3658 pmState == PM_RUN || 3659 pmState == PM_STOP_BACKENDS || 3660 pmState == PM_SHUTDOWN) 3661 pmState = PM_WAIT_BACKENDS; 3662 3663 /* 3664 * .. and if this doesn't happen quickly enough, now the clock is ticking 3665 * for us to kill them without mercy. 3666 */ 3667 if (AbortStartTime == 0) 3668 AbortStartTime = time(NULL); 3669 } 3670 3671 /* 3672 * Log the death of a child process. 3673 */ 3674 static void 3675 LogChildExit(int lev, const char *procname, int pid, int exitstatus) 3676 { 3677 /* 3678 * size of activity_buffer is arbitrary, but set equal to default 3679 * track_activity_query_size 3680 */ 3681 char activity_buffer[1024]; 3682 const char *activity = NULL; 3683 3684 if (!EXIT_STATUS_0(exitstatus)) 3685 activity = pgstat_get_crashed_backend_activity(pid, 3686 activity_buffer, 3687 sizeof(activity_buffer)); 3688 3689 if (WIFEXITED(exitstatus)) 3690 ereport(lev, 3691 3692 /*------ 3693 translator: %s is a noun phrase describing a child process, such as 3694 "server process" */ 3695 (errmsg("%s (PID %d) exited with exit code %d", 3696 procname, pid, WEXITSTATUS(exitstatus)), 3697 activity ? errdetail("Failed process was running: %s", activity) : 0)); 3698 else if (WIFSIGNALED(exitstatus)) 3699 { 3700 #if defined(WIN32) 3701 ereport(lev, 3702 3703 /*------ 3704 translator: %s is a noun phrase describing a child process, such as 3705 "server process" */ 3706 (errmsg("%s (PID %d) was terminated by exception 0x%X", 3707 procname, pid, WTERMSIG(exitstatus)), 3708 errhint("See C include file \"ntstatus.h\" for a description of the hexadecimal value."), 3709 activity ? errdetail("Failed process was running: %s", activity) : 0)); 3710 #else 3711 ereport(lev, 3712 3713 /*------ 3714 translator: %s is a noun phrase describing a child process, such as 3715 "server process" */ 3716 (errmsg("%s (PID %d) was terminated by signal %d: %s", 3717 procname, pid, WTERMSIG(exitstatus), 3718 pg_strsignal(WTERMSIG(exitstatus))), 3719 activity ? errdetail("Failed process was running: %s", activity) : 0)); 3720 #endif 3721 } 3722 else 3723 ereport(lev, 3724 3725 /*------ 3726 translator: %s is a noun phrase describing a child process, such as 3727 "server process" */ 3728 (errmsg("%s (PID %d) exited with unrecognized status %d", 3729 procname, pid, exitstatus), 3730 activity ? errdetail("Failed process was running: %s", activity) : 0)); 3731 } 3732 3733 /* 3734 * Advance the postmaster's state machine and take actions as appropriate 3735 * 3736 * This is common code for pmdie(), reaper() and sigusr1_handler(), which 3737 * receive the signals that might mean we need to change state. 3738 */ 3739 static void 3740 PostmasterStateMachine(void) 3741 { 3742 /* If we're doing a smart shutdown, try to advance that state. */ 3743 if (pmState == PM_RUN || pmState == PM_HOT_STANDBY) 3744 { 3745 if (connsAllowed == ALLOW_SUPERUSER_CONNS) 3746 { 3747 /* 3748 * ALLOW_SUPERUSER_CONNS state ends as soon as online backup mode 3749 * is not active. 3750 */ 3751 if (!BackupInProgress()) 3752 connsAllowed = ALLOW_NO_CONNS; 3753 } 3754 3755 if (connsAllowed == ALLOW_NO_CONNS) 3756 { 3757 /* 3758 * ALLOW_NO_CONNS state ends when we have no normal client 3759 * backends running. Then we're ready to stop other children. 3760 */ 3761 if (CountChildren(BACKEND_TYPE_NORMAL) == 0) 3762 pmState = PM_STOP_BACKENDS; 3763 } 3764 } 3765 3766 /* 3767 * If we're ready to do so, signal child processes to shut down. (This 3768 * isn't a persistent state, but treating it as a distinct pmState allows 3769 * us to share this code across multiple shutdown code paths.) 3770 */ 3771 if (pmState == PM_STOP_BACKENDS) 3772 { 3773 /* 3774 * Forget any pending requests for background workers, since we're no 3775 * longer willing to launch any new workers. (If additional requests 3776 * arrive, BackgroundWorkerStateChange will reject them.) 3777 */ 3778 ForgetUnstartedBackgroundWorkers(); 3779 3780 /* Signal all backend children except walsenders */ 3781 SignalSomeChildren(SIGTERM, 3782 BACKEND_TYPE_ALL - BACKEND_TYPE_WALSND); 3783 /* and the autovac launcher too */ 3784 if (AutoVacPID != 0) 3785 signal_child(AutoVacPID, SIGTERM); 3786 /* and the bgwriter too */ 3787 if (BgWriterPID != 0) 3788 signal_child(BgWriterPID, SIGTERM); 3789 /* and the walwriter too */ 3790 if (WalWriterPID != 0) 3791 signal_child(WalWriterPID, SIGTERM); 3792 /* If we're in recovery, also stop startup and walreceiver procs */ 3793 if (StartupPID != 0) 3794 signal_child(StartupPID, SIGTERM); 3795 if (WalReceiverPID != 0) 3796 signal_child(WalReceiverPID, SIGTERM); 3797 /* checkpointer, archiver, stats, and syslogger may continue for now */ 3798 3799 /* Now transition to PM_WAIT_BACKENDS state to wait for them to die */ 3800 pmState = PM_WAIT_BACKENDS; 3801 } 3802 3803 /* 3804 * If we are in a state-machine state that implies waiting for backends to 3805 * exit, see if they're all gone, and change state if so. 3806 */ 3807 if (pmState == PM_WAIT_BACKENDS) 3808 { 3809 /* 3810 * PM_WAIT_BACKENDS state ends when we have no regular backends 3811 * (including autovac workers), no bgworkers (including unconnected 3812 * ones), and no walwriter, autovac launcher or bgwriter. If we are 3813 * doing crash recovery or an immediate shutdown then we expect the 3814 * checkpointer to exit as well, otherwise not. The archiver, stats, 3815 * and syslogger processes are disregarded since they are not 3816 * connected to shared memory; we also disregard dead_end children 3817 * here. Walsenders are also disregarded, they will be terminated 3818 * later after writing the checkpoint record, like the archiver 3819 * process. 3820 */ 3821 if (CountChildren(BACKEND_TYPE_ALL - BACKEND_TYPE_WALSND) == 0 && 3822 StartupPID == 0 && 3823 WalReceiverPID == 0 && 3824 BgWriterPID == 0 && 3825 (CheckpointerPID == 0 || 3826 (!FatalError && Shutdown < ImmediateShutdown)) && 3827 WalWriterPID == 0 && 3828 AutoVacPID == 0) 3829 { 3830 if (Shutdown >= ImmediateShutdown || FatalError) 3831 { 3832 /* 3833 * Start waiting for dead_end children to die. This state 3834 * change causes ServerLoop to stop creating new ones. 3835 */ 3836 pmState = PM_WAIT_DEAD_END; 3837 3838 /* 3839 * We already SIGQUIT'd the archiver and stats processes, if 3840 * any, when we started immediate shutdown or entered 3841 * FatalError state. 3842 */ 3843 } 3844 else 3845 { 3846 /* 3847 * If we get here, we are proceeding with normal shutdown. All 3848 * the regular children are gone, and it's time to tell the 3849 * checkpointer to do a shutdown checkpoint. 3850 */ 3851 Assert(Shutdown > NoShutdown); 3852 /* Start the checkpointer if not running */ 3853 if (CheckpointerPID == 0) 3854 CheckpointerPID = StartCheckpointer(); 3855 /* And tell it to shut down */ 3856 if (CheckpointerPID != 0) 3857 { 3858 signal_child(CheckpointerPID, SIGUSR2); 3859 pmState = PM_SHUTDOWN; 3860 } 3861 else 3862 { 3863 /* 3864 * If we failed to fork a checkpointer, just shut down. 3865 * Any required cleanup will happen at next restart. We 3866 * set FatalError so that an "abnormal shutdown" message 3867 * gets logged when we exit. 3868 */ 3869 FatalError = true; 3870 pmState = PM_WAIT_DEAD_END; 3871 3872 /* Kill the walsenders, archiver and stats collector too */ 3873 SignalChildren(SIGQUIT); 3874 if (PgArchPID != 0) 3875 signal_child(PgArchPID, SIGQUIT); 3876 if (PgStatPID != 0) 3877 signal_child(PgStatPID, SIGQUIT); 3878 } 3879 } 3880 } 3881 } 3882 3883 if (pmState == PM_SHUTDOWN_2) 3884 { 3885 /* 3886 * PM_SHUTDOWN_2 state ends when there's no other children than 3887 * dead_end children left. There shouldn't be any regular backends 3888 * left by now anyway; what we're really waiting for is walsenders and 3889 * archiver. 3890 */ 3891 if (PgArchPID == 0 && CountChildren(BACKEND_TYPE_ALL) == 0) 3892 { 3893 pmState = PM_WAIT_DEAD_END; 3894 } 3895 } 3896 3897 if (pmState == PM_WAIT_DEAD_END) 3898 { 3899 /* 3900 * PM_WAIT_DEAD_END state ends when the BackendList is entirely empty 3901 * (ie, no dead_end children remain), and the archiver and stats 3902 * collector are gone too. 3903 * 3904 * The reason we wait for those two is to protect them against a new 3905 * postmaster starting conflicting subprocesses; this isn't an 3906 * ironclad protection, but it at least helps in the 3907 * shutdown-and-immediately-restart scenario. Note that they have 3908 * already been sent appropriate shutdown signals, either during a 3909 * normal state transition leading up to PM_WAIT_DEAD_END, or during 3910 * FatalError processing. 3911 */ 3912 if (dlist_is_empty(&BackendList) && 3913 PgArchPID == 0 && PgStatPID == 0) 3914 { 3915 /* These other guys should be dead already */ 3916 Assert(StartupPID == 0); 3917 Assert(WalReceiverPID == 0); 3918 Assert(BgWriterPID == 0); 3919 Assert(CheckpointerPID == 0); 3920 Assert(WalWriterPID == 0); 3921 Assert(AutoVacPID == 0); 3922 /* syslogger is not considered here */ 3923 pmState = PM_NO_CHILDREN; 3924 } 3925 } 3926 3927 /* 3928 * If we've been told to shut down, we exit as soon as there are no 3929 * remaining children. If there was a crash, cleanup will occur at the 3930 * next startup. (Before PostgreSQL 8.3, we tried to recover from the 3931 * crash before exiting, but that seems unwise if we are quitting because 3932 * we got SIGTERM from init --- there may well not be time for recovery 3933 * before init decides to SIGKILL us.) 3934 * 3935 * Note that the syslogger continues to run. It will exit when it sees 3936 * EOF on its input pipe, which happens when there are no more upstream 3937 * processes. 3938 */ 3939 if (Shutdown > NoShutdown && pmState == PM_NO_CHILDREN) 3940 { 3941 if (FatalError) 3942 { 3943 ereport(LOG, (errmsg("abnormal database system shutdown"))); 3944 ExitPostmaster(1); 3945 } 3946 else 3947 { 3948 /* 3949 * Terminate exclusive backup mode to avoid recovery after a clean 3950 * fast shutdown. Since an exclusive backup can only be taken 3951 * during normal running (and not, for example, while running 3952 * under Hot Standby) it only makes sense to do this if we reached 3953 * normal running. If we're still in recovery, the backup file is 3954 * one we're recovering *from*, and we must keep it around so that 3955 * recovery restarts from the right place. 3956 */ 3957 if (ReachedNormalRunning) 3958 CancelBackup(); 3959 3960 /* Normal exit from the postmaster is here */ 3961 ExitPostmaster(0); 3962 } 3963 } 3964 3965 /* 3966 * If the startup process failed, or the user does not want an automatic 3967 * restart after backend crashes, wait for all non-syslogger children to 3968 * exit, and then exit postmaster. We don't try to reinitialize when the 3969 * startup process fails, because more than likely it will just fail again 3970 * and we will keep trying forever. 3971 */ 3972 if (pmState == PM_NO_CHILDREN && 3973 (StartupStatus == STARTUP_CRASHED || !restart_after_crash)) 3974 ExitPostmaster(1); 3975 3976 /* 3977 * If we need to recover from a crash, wait for all non-syslogger children 3978 * to exit, then reset shmem and StartupDataBase. 3979 */ 3980 if (FatalError && pmState == PM_NO_CHILDREN) 3981 { 3982 ereport(LOG, 3983 (errmsg("all server processes terminated; reinitializing"))); 3984 3985 /* allow background workers to immediately restart */ 3986 ResetBackgroundWorkerCrashTimes(); 3987 3988 shmem_exit(1); 3989 3990 /* re-read control file into local memory */ 3991 LocalProcessControlFile(true); 3992 3993 reset_shared(PostPortNumber); 3994 3995 StartupPID = StartupDataBase(); 3996 Assert(StartupPID != 0); 3997 StartupStatus = STARTUP_RUNNING; 3998 pmState = PM_STARTUP; 3999 /* crash recovery started, reset SIGKILL flag */ 4000 AbortStartTime = 0; 4001 } 4002 } 4003 4004 4005 /* 4006 * Send a signal to a postmaster child process 4007 * 4008 * On systems that have setsid(), each child process sets itself up as a 4009 * process group leader. For signals that are generally interpreted in the 4010 * appropriate fashion, we signal the entire process group not just the 4011 * direct child process. This allows us to, for example, SIGQUIT a blocked 4012 * archive_recovery script, or SIGINT a script being run by a backend via 4013 * system(). 4014 * 4015 * There is a race condition for recently-forked children: they might not 4016 * have executed setsid() yet. So we signal the child directly as well as 4017 * the group. We assume such a child will handle the signal before trying 4018 * to spawn any grandchild processes. We also assume that signaling the 4019 * child twice will not cause any problems. 4020 */ 4021 static void 4022 signal_child(pid_t pid, int signal) 4023 { 4024 if (kill(pid, signal) < 0) 4025 elog(DEBUG3, "kill(%ld,%d) failed: %m", (long) pid, signal); 4026 #ifdef HAVE_SETSID 4027 switch (signal) 4028 { 4029 case SIGINT: 4030 case SIGTERM: 4031 case SIGQUIT: 4032 case SIGSTOP: 4033 case SIGKILL: 4034 if (kill(-pid, signal) < 0) 4035 elog(DEBUG3, "kill(%ld,%d) failed: %m", (long) (-pid), signal); 4036 break; 4037 default: 4038 break; 4039 } 4040 #endif 4041 } 4042 4043 /* 4044 * Send a signal to the targeted children (but NOT special children; 4045 * dead_end children are never signaled, either). 4046 */ 4047 static bool 4048 SignalSomeChildren(int signal, int target) 4049 { 4050 dlist_iter iter; 4051 bool signaled = false; 4052 4053 dlist_foreach(iter, &BackendList) 4054 { 4055 Backend *bp = dlist_container(Backend, elem, iter.cur); 4056 4057 if (bp->dead_end) 4058 continue; 4059 4060 /* 4061 * Since target == BACKEND_TYPE_ALL is the most common case, we test 4062 * it first and avoid touching shared memory for every child. 4063 */ 4064 if (target != BACKEND_TYPE_ALL) 4065 { 4066 /* 4067 * Assign bkend_type for any recently announced WAL Sender 4068 * processes. 4069 */ 4070 if (bp->bkend_type == BACKEND_TYPE_NORMAL && 4071 IsPostmasterChildWalSender(bp->child_slot)) 4072 bp->bkend_type = BACKEND_TYPE_WALSND; 4073 4074 if (!(target & bp->bkend_type)) 4075 continue; 4076 } 4077 4078 ereport(DEBUG4, 4079 (errmsg_internal("sending signal %d to process %d", 4080 signal, (int) bp->pid))); 4081 signal_child(bp->pid, signal); 4082 signaled = true; 4083 } 4084 return signaled; 4085 } 4086 4087 /* 4088 * Send a termination signal to children. This considers all of our children 4089 * processes, except syslogger and dead_end backends. 4090 */ 4091 static void 4092 TerminateChildren(int signal) 4093 { 4094 SignalChildren(signal); 4095 if (StartupPID != 0) 4096 { 4097 signal_child(StartupPID, signal); 4098 if (signal == SIGQUIT || signal == SIGKILL) 4099 StartupStatus = STARTUP_SIGNALED; 4100 } 4101 if (BgWriterPID != 0) 4102 signal_child(BgWriterPID, signal); 4103 if (CheckpointerPID != 0) 4104 signal_child(CheckpointerPID, signal); 4105 if (WalWriterPID != 0) 4106 signal_child(WalWriterPID, signal); 4107 if (WalReceiverPID != 0) 4108 signal_child(WalReceiverPID, signal); 4109 if (AutoVacPID != 0) 4110 signal_child(AutoVacPID, signal); 4111 if (PgArchPID != 0) 4112 signal_child(PgArchPID, signal); 4113 if (PgStatPID != 0) 4114 signal_child(PgStatPID, signal); 4115 } 4116 4117 /* 4118 * BackendStartup -- start backend process 4119 * 4120 * returns: STATUS_ERROR if the fork failed, STATUS_OK otherwise. 4121 * 4122 * Note: if you change this code, also consider StartAutovacuumWorker. 4123 */ 4124 static int 4125 BackendStartup(Port *port) 4126 { 4127 Backend *bn; /* for backend cleanup */ 4128 pid_t pid; 4129 4130 /* 4131 * Create backend data structure. Better before the fork() so we can 4132 * handle failure cleanly. 4133 */ 4134 bn = (Backend *) malloc(sizeof(Backend)); 4135 if (!bn) 4136 { 4137 ereport(LOG, 4138 (errcode(ERRCODE_OUT_OF_MEMORY), 4139 errmsg("out of memory"))); 4140 return STATUS_ERROR; 4141 } 4142 4143 /* 4144 * Compute the cancel key that will be assigned to this backend. The 4145 * backend will have its own copy in the forked-off process' value of 4146 * MyCancelKey, so that it can transmit the key to the frontend. 4147 */ 4148 if (!RandomCancelKey(&MyCancelKey)) 4149 { 4150 free(bn); 4151 ereport(LOG, 4152 (errcode(ERRCODE_INTERNAL_ERROR), 4153 errmsg("could not generate random cancel key"))); 4154 return STATUS_ERROR; 4155 } 4156 4157 bn->cancel_key = MyCancelKey; 4158 4159 /* Pass down canAcceptConnections state */ 4160 port->canAcceptConnections = canAcceptConnections(BACKEND_TYPE_NORMAL); 4161 bn->dead_end = (port->canAcceptConnections != CAC_OK && 4162 port->canAcceptConnections != CAC_SUPERUSER); 4163 4164 /* 4165 * Unless it's a dead_end child, assign it a child slot number 4166 */ 4167 if (!bn->dead_end) 4168 bn->child_slot = MyPMChildSlot = AssignPostmasterChildSlot(); 4169 else 4170 bn->child_slot = 0; 4171 4172 /* Hasn't asked to be notified about any bgworkers yet */ 4173 bn->bgworker_notify = false; 4174 4175 #ifdef EXEC_BACKEND 4176 pid = backend_forkexec(port); 4177 #else /* !EXEC_BACKEND */ 4178 pid = fork_process(); 4179 if (pid == 0) /* child */ 4180 { 4181 free(bn); 4182 4183 /* Detangle from postmaster */ 4184 InitPostmasterChild(); 4185 4186 /* Close the postmaster's sockets */ 4187 ClosePostmasterPorts(false); 4188 4189 /* Perform additional initialization and collect startup packet */ 4190 BackendInitialize(port); 4191 4192 /* And run the backend */ 4193 BackendRun(port); 4194 } 4195 #endif /* EXEC_BACKEND */ 4196 4197 if (pid < 0) 4198 { 4199 /* in parent, fork failed */ 4200 int save_errno = errno; 4201 4202 if (!bn->dead_end) 4203 (void) ReleasePostmasterChildSlot(bn->child_slot); 4204 free(bn); 4205 errno = save_errno; 4206 ereport(LOG, 4207 (errmsg("could not fork new process for connection: %m"))); 4208 report_fork_failure_to_client(port, save_errno); 4209 return STATUS_ERROR; 4210 } 4211 4212 /* in parent, successful fork */ 4213 ereport(DEBUG2, 4214 (errmsg_internal("forked new backend, pid=%d socket=%d", 4215 (int) pid, (int) port->sock))); 4216 4217 /* 4218 * Everything's been successful, it's safe to add this backend to our list 4219 * of backends. 4220 */ 4221 bn->pid = pid; 4222 bn->bkend_type = BACKEND_TYPE_NORMAL; /* Can change later to WALSND */ 4223 dlist_push_head(&BackendList, &bn->elem); 4224 4225 #ifdef EXEC_BACKEND 4226 if (!bn->dead_end) 4227 ShmemBackendArrayAdd(bn); 4228 #endif 4229 4230 return STATUS_OK; 4231 } 4232 4233 /* 4234 * Try to report backend fork() failure to client before we close the 4235 * connection. Since we do not care to risk blocking the postmaster on 4236 * this connection, we set the connection to non-blocking and try only once. 4237 * 4238 * This is grungy special-purpose code; we cannot use backend libpq since 4239 * it's not up and running. 4240 */ 4241 static void 4242 report_fork_failure_to_client(Port *port, int errnum) 4243 { 4244 char buffer[1000]; 4245 int rc; 4246 4247 /* Format the error message packet (always V2 protocol) */ 4248 snprintf(buffer, sizeof(buffer), "E%s%s\n", 4249 _("could not fork new process for connection: "), 4250 strerror(errnum)); 4251 4252 /* Set port to non-blocking. Don't do send() if this fails */ 4253 if (!pg_set_noblock(port->sock)) 4254 return; 4255 4256 /* We'll retry after EINTR, but ignore all other failures */ 4257 do 4258 { 4259 rc = send(port->sock, buffer, strlen(buffer) + 1, 0); 4260 } while (rc < 0 && errno == EINTR); 4261 } 4262 4263 4264 /* 4265 * BackendInitialize -- initialize an interactive (postmaster-child) 4266 * backend process, and collect the client's startup packet. 4267 * 4268 * returns: nothing. Will not return at all if there's any failure. 4269 * 4270 * Note: this code does not depend on having any access to shared memory. 4271 * In the EXEC_BACKEND case, we are physically attached to shared memory 4272 * but have not yet set up most of our local pointers to shmem structures. 4273 */ 4274 static void 4275 BackendInitialize(Port *port) 4276 { 4277 int status; 4278 int ret; 4279 char remote_host[NI_MAXHOST]; 4280 char remote_port[NI_MAXSERV]; 4281 char remote_ps_data[NI_MAXHOST]; 4282 4283 /* Save port etc. for ps status */ 4284 MyProcPort = port; 4285 4286 /* 4287 * PreAuthDelay is a debugging aid for investigating problems in the 4288 * authentication cycle: it can be set in postgresql.conf to allow time to 4289 * attach to the newly-forked backend with a debugger. (See also 4290 * PostAuthDelay, which we allow clients to pass through PGOPTIONS, but it 4291 * is not honored until after authentication.) 4292 */ 4293 if (PreAuthDelay > 0) 4294 pg_usleep(PreAuthDelay * 1000000L); 4295 4296 /* This flag will remain set until InitPostgres finishes authentication */ 4297 ClientAuthInProgress = true; /* limit visibility of log messages */ 4298 4299 /* set these to empty in case they are needed before we set them up */ 4300 port->remote_host = ""; 4301 port->remote_port = ""; 4302 4303 /* 4304 * Initialize libpq and enable reporting of ereport errors to the client. 4305 * Must do this now because authentication uses libpq to send messages. 4306 */ 4307 pq_init(); /* initialize libpq to talk to client */ 4308 whereToSendOutput = DestRemote; /* now safe to ereport to client */ 4309 4310 /* 4311 * We arrange to do proc_exit(1) if we receive SIGTERM or timeout while 4312 * trying to collect the startup packet; while SIGQUIT results in 4313 * _exit(2). Otherwise the postmaster cannot shutdown the database FAST 4314 * or IMMED cleanly if a buggy client fails to send the packet promptly. 4315 * 4316 * XXX this is pretty dangerous; signal handlers should not call anything 4317 * as complex as proc_exit() directly. We minimize the hazard by not 4318 * keeping these handlers active for longer than we must. However, it 4319 * seems necessary to be able to escape out of DNS lookups as well as the 4320 * startup packet reception proper, so we can't narrow the scope further 4321 * than is done here. 4322 * 4323 * XXX it follows that the remainder of this function must tolerate losing 4324 * control at any instant. Likewise, any pg_on_exit_callback registered 4325 * before or during this function must be prepared to execute at any 4326 * instant between here and the end of this function. Furthermore, 4327 * affected callbacks execute partially or not at all when a second 4328 * exit-inducing signal arrives after proc_exit_prepare() decrements 4329 * on_proc_exit_index. (Thanks to that mechanic, callbacks need not 4330 * anticipate more than one call.) This is fragile; it ought to instead 4331 * follow the norm of handling interrupts at selected, safe opportunities. 4332 */ 4333 pqsignal(SIGTERM, process_startup_packet_die); 4334 pqsignal(SIGQUIT, process_startup_packet_quickdie); 4335 InitializeTimeouts(); /* establishes SIGALRM handler */ 4336 PG_SETMASK(&StartupBlockSig); 4337 4338 /* 4339 * Get the remote host name and port for logging and status display. 4340 */ 4341 remote_host[0] = '\0'; 4342 remote_port[0] = '\0'; 4343 if ((ret = pg_getnameinfo_all(&port->raddr.addr, port->raddr.salen, 4344 remote_host, sizeof(remote_host), 4345 remote_port, sizeof(remote_port), 4346 (log_hostname ? 0 : NI_NUMERICHOST) | NI_NUMERICSERV)) != 0) 4347 ereport(WARNING, 4348 (errmsg_internal("pg_getnameinfo_all() failed: %s", 4349 gai_strerror(ret)))); 4350 if (remote_port[0] == '\0') 4351 snprintf(remote_ps_data, sizeof(remote_ps_data), "%s", remote_host); 4352 else 4353 snprintf(remote_ps_data, sizeof(remote_ps_data), "%s(%s)", remote_host, remote_port); 4354 4355 /* 4356 * Save remote_host and remote_port in port structure (after this, they 4357 * will appear in log_line_prefix data for log messages). 4358 */ 4359 port->remote_host = strdup(remote_host); 4360 port->remote_port = strdup(remote_port); 4361 4362 /* And now we can issue the Log_connections message, if wanted */ 4363 if (Log_connections) 4364 { 4365 if (remote_port[0]) 4366 ereport(LOG, 4367 (errmsg("connection received: host=%s port=%s", 4368 remote_host, 4369 remote_port))); 4370 else 4371 ereport(LOG, 4372 (errmsg("connection received: host=%s", 4373 remote_host))); 4374 } 4375 4376 /* 4377 * If we did a reverse lookup to name, we might as well save the results 4378 * rather than possibly repeating the lookup during authentication. 4379 * 4380 * Note that we don't want to specify NI_NAMEREQD above, because then we'd 4381 * get nothing useful for a client without an rDNS entry. Therefore, we 4382 * must check whether we got a numeric IPv4 or IPv6 address, and not save 4383 * it into remote_hostname if so. (This test is conservative and might 4384 * sometimes classify a hostname as numeric, but an error in that 4385 * direction is safe; it only results in a possible extra lookup.) 4386 */ 4387 if (log_hostname && 4388 ret == 0 && 4389 strspn(remote_host, "0123456789.") < strlen(remote_host) && 4390 strspn(remote_host, "0123456789ABCDEFabcdef:") < strlen(remote_host)) 4391 port->remote_hostname = strdup(remote_host); 4392 4393 /* 4394 * Ready to begin client interaction. We will give up and proc_exit(1) 4395 * after a time delay, so that a broken client can't hog a connection 4396 * indefinitely. PreAuthDelay and any DNS interactions above don't count 4397 * against the time limit. 4398 * 4399 * Note: AuthenticationTimeout is applied here while waiting for the 4400 * startup packet, and then again in InitPostgres for the duration of any 4401 * authentication operations. So a hostile client could tie up the 4402 * process for nearly twice AuthenticationTimeout before we kick him off. 4403 * 4404 * Note: because PostgresMain will call InitializeTimeouts again, the 4405 * registration of STARTUP_PACKET_TIMEOUT will be lost. This is okay 4406 * since we never use it again after this function. 4407 */ 4408 RegisterTimeout(STARTUP_PACKET_TIMEOUT, StartupPacketTimeoutHandler); 4409 enable_timeout_after(STARTUP_PACKET_TIMEOUT, AuthenticationTimeout * 1000); 4410 4411 /* 4412 * Receive the startup packet (which might turn out to be a cancel request 4413 * packet). 4414 */ 4415 status = ProcessStartupPacket(port, false, false); 4416 4417 /* 4418 * Disable the timeout, and prevent SIGTERM/SIGQUIT again. 4419 */ 4420 disable_timeout(STARTUP_PACKET_TIMEOUT, false); 4421 PG_SETMASK(&BlockSig); 4422 4423 /* 4424 * Stop here if it was bad or a cancel packet. ProcessStartupPacket 4425 * already did any appropriate error reporting. 4426 */ 4427 if (status != STATUS_OK) 4428 proc_exit(0); 4429 4430 /* 4431 * Now that we have the user and database name, we can set the process 4432 * title for ps. It's good to do this as early as possible in startup. 4433 * 4434 * For a walsender, the ps display is set in the following form: 4435 * 4436 * postgres: walsender <user> <host> <activity> 4437 * 4438 * To achieve that, we pass "walsender" as username and username as dbname 4439 * to init_ps_display(). XXX: should add a new variant of 4440 * init_ps_display() to avoid abusing the parameters like this. 4441 */ 4442 if (am_walsender) 4443 init_ps_display(pgstat_get_backend_desc(B_WAL_SENDER), port->user_name, remote_ps_data, 4444 update_process_title ? "authentication" : ""); 4445 else 4446 init_ps_display(port->user_name, port->database_name, remote_ps_data, 4447 update_process_title ? "authentication" : ""); 4448 } 4449 4450 4451 /* 4452 * BackendRun -- set up the backend's argument list and invoke PostgresMain() 4453 * 4454 * returns: 4455 * Shouldn't return at all. 4456 * If PostgresMain() fails, return status. 4457 */ 4458 static void 4459 BackendRun(Port *port) 4460 { 4461 char **av; 4462 int maxac; 4463 int ac; 4464 int i; 4465 4466 /* 4467 * Now, build the argv vector that will be given to PostgresMain. 4468 * 4469 * The maximum possible number of commandline arguments that could come 4470 * from ExtraOptions is (strlen(ExtraOptions) + 1) / 2; see 4471 * pg_split_opts(). 4472 */ 4473 maxac = 2; /* for fixed args supplied below */ 4474 maxac += (strlen(ExtraOptions) + 1) / 2; 4475 4476 av = (char **) MemoryContextAlloc(TopMemoryContext, 4477 maxac * sizeof(char *)); 4478 ac = 0; 4479 4480 av[ac++] = "postgres"; 4481 4482 /* 4483 * Pass any backend switches specified with -o on the postmaster's own 4484 * command line. We assume these are secure. 4485 */ 4486 pg_split_opts(av, &ac, ExtraOptions); 4487 4488 av[ac] = NULL; 4489 4490 Assert(ac < maxac); 4491 4492 /* 4493 * Debug: print arguments being passed to backend 4494 */ 4495 ereport(DEBUG3, 4496 (errmsg_internal("%s child[%d]: starting with (", 4497 progname, (int) getpid()))); 4498 for (i = 0; i < ac; ++i) 4499 ereport(DEBUG3, 4500 (errmsg_internal("\t%s", av[i]))); 4501 ereport(DEBUG3, 4502 (errmsg_internal(")"))); 4503 4504 /* 4505 * Make sure we aren't in PostmasterContext anymore. (We can't delete it 4506 * just yet, though, because InitPostgres will need the HBA data.) 4507 */ 4508 MemoryContextSwitchTo(TopMemoryContext); 4509 4510 PostgresMain(ac, av, port->database_name, port->user_name); 4511 } 4512 4513 4514 #ifdef EXEC_BACKEND 4515 4516 /* 4517 * postmaster_forkexec -- fork and exec a postmaster subprocess 4518 * 4519 * The caller must have set up the argv array already, except for argv[2] 4520 * which will be filled with the name of the temp variable file. 4521 * 4522 * Returns the child process PID, or -1 on fork failure (a suitable error 4523 * message has been logged on failure). 4524 * 4525 * All uses of this routine will dispatch to SubPostmasterMain in the 4526 * child process. 4527 */ 4528 pid_t 4529 postmaster_forkexec(int argc, char *argv[]) 4530 { 4531 Port port; 4532 4533 /* This entry point passes dummy values for the Port variables */ 4534 memset(&port, 0, sizeof(port)); 4535 return internal_forkexec(argc, argv, &port); 4536 } 4537 4538 /* 4539 * backend_forkexec -- fork/exec off a backend process 4540 * 4541 * Some operating systems (WIN32) don't have fork() so we have to simulate 4542 * it by storing parameters that need to be passed to the child and 4543 * then create a new child process. 4544 * 4545 * returns the pid of the fork/exec'd process, or -1 on failure 4546 */ 4547 static pid_t 4548 backend_forkexec(Port *port) 4549 { 4550 char *av[4]; 4551 int ac = 0; 4552 4553 av[ac++] = "postgres"; 4554 av[ac++] = "--forkbackend"; 4555 av[ac++] = NULL; /* filled in by internal_forkexec */ 4556 4557 av[ac] = NULL; 4558 Assert(ac < lengthof(av)); 4559 4560 return internal_forkexec(ac, av, port); 4561 } 4562 4563 #ifndef WIN32 4564 4565 /* 4566 * internal_forkexec non-win32 implementation 4567 * 4568 * - writes out backend variables to the parameter file 4569 * - fork():s, and then exec():s the child process 4570 */ 4571 static pid_t 4572 internal_forkexec(int argc, char *argv[], Port *port) 4573 { 4574 static unsigned long tmpBackendFileNum = 0; 4575 pid_t pid; 4576 char tmpfilename[MAXPGPATH]; 4577 BackendParameters param; 4578 FILE *fp; 4579 4580 if (!save_backend_variables(¶m, port)) 4581 return -1; /* log made by save_backend_variables */ 4582 4583 /* Calculate name for temp file */ 4584 snprintf(tmpfilename, MAXPGPATH, "%s/%s.backend_var.%d.%lu", 4585 PG_TEMP_FILES_DIR, PG_TEMP_FILE_PREFIX, 4586 MyProcPid, ++tmpBackendFileNum); 4587 4588 /* Open file */ 4589 fp = AllocateFile(tmpfilename, PG_BINARY_W); 4590 if (!fp) 4591 { 4592 /* 4593 * As in OpenTemporaryFileInTablespace, try to make the temp-file 4594 * directory, ignoring errors. 4595 */ 4596 (void) MakePGDirectory(PG_TEMP_FILES_DIR); 4597 4598 fp = AllocateFile(tmpfilename, PG_BINARY_W); 4599 if (!fp) 4600 { 4601 ereport(LOG, 4602 (errcode_for_file_access(), 4603 errmsg("could not create file \"%s\": %m", 4604 tmpfilename))); 4605 return -1; 4606 } 4607 } 4608 4609 if (fwrite(¶m, sizeof(param), 1, fp) != 1) 4610 { 4611 ereport(LOG, 4612 (errcode_for_file_access(), 4613 errmsg("could not write to file \"%s\": %m", tmpfilename))); 4614 FreeFile(fp); 4615 return -1; 4616 } 4617 4618 /* Release file */ 4619 if (FreeFile(fp)) 4620 { 4621 ereport(LOG, 4622 (errcode_for_file_access(), 4623 errmsg("could not write to file \"%s\": %m", tmpfilename))); 4624 return -1; 4625 } 4626 4627 /* Make sure caller set up argv properly */ 4628 Assert(argc >= 3); 4629 Assert(argv[argc] == NULL); 4630 Assert(strncmp(argv[1], "--fork", 6) == 0); 4631 Assert(argv[2] == NULL); 4632 4633 /* Insert temp file name after --fork argument */ 4634 argv[2] = tmpfilename; 4635 4636 /* Fire off execv in child */ 4637 if ((pid = fork_process()) == 0) 4638 { 4639 if (execv(postgres_exec_path, argv) < 0) 4640 { 4641 ereport(LOG, 4642 (errmsg("could not execute server process \"%s\": %m", 4643 postgres_exec_path))); 4644 /* We're already in the child process here, can't return */ 4645 exit(1); 4646 } 4647 } 4648 4649 return pid; /* Parent returns pid, or -1 on fork failure */ 4650 } 4651 #else /* WIN32 */ 4652 4653 /* 4654 * internal_forkexec win32 implementation 4655 * 4656 * - starts backend using CreateProcess(), in suspended state 4657 * - writes out backend variables to the parameter file 4658 * - during this, duplicates handles and sockets required for 4659 * inheritance into the new process 4660 * - resumes execution of the new process once the backend parameter 4661 * file is complete. 4662 */ 4663 static pid_t 4664 internal_forkexec(int argc, char *argv[], Port *port) 4665 { 4666 int retry_count = 0; 4667 STARTUPINFO si; 4668 PROCESS_INFORMATION pi; 4669 int i; 4670 int j; 4671 char cmdLine[MAXPGPATH * 2]; 4672 HANDLE paramHandle; 4673 BackendParameters *param; 4674 SECURITY_ATTRIBUTES sa; 4675 char paramHandleStr[32]; 4676 win32_deadchild_waitinfo *childinfo; 4677 4678 /* Make sure caller set up argv properly */ 4679 Assert(argc >= 3); 4680 Assert(argv[argc] == NULL); 4681 Assert(strncmp(argv[1], "--fork", 6) == 0); 4682 Assert(argv[2] == NULL); 4683 4684 /* Resume here if we need to retry */ 4685 retry: 4686 4687 /* Set up shared memory for parameter passing */ 4688 ZeroMemory(&sa, sizeof(sa)); 4689 sa.nLength = sizeof(sa); 4690 sa.bInheritHandle = TRUE; 4691 paramHandle = CreateFileMapping(INVALID_HANDLE_VALUE, 4692 &sa, 4693 PAGE_READWRITE, 4694 0, 4695 sizeof(BackendParameters), 4696 NULL); 4697 if (paramHandle == INVALID_HANDLE_VALUE) 4698 { 4699 elog(LOG, "could not create backend parameter file mapping: error code %lu", 4700 GetLastError()); 4701 return -1; 4702 } 4703 4704 param = MapViewOfFile(paramHandle, FILE_MAP_WRITE, 0, 0, sizeof(BackendParameters)); 4705 if (!param) 4706 { 4707 elog(LOG, "could not map backend parameter memory: error code %lu", 4708 GetLastError()); 4709 CloseHandle(paramHandle); 4710 return -1; 4711 } 4712 4713 /* Insert temp file name after --fork argument */ 4714 #ifdef _WIN64 4715 sprintf(paramHandleStr, "%llu", (LONG_PTR) paramHandle); 4716 #else 4717 sprintf(paramHandleStr, "%lu", (DWORD) paramHandle); 4718 #endif 4719 argv[2] = paramHandleStr; 4720 4721 /* Format the cmd line */ 4722 cmdLine[sizeof(cmdLine) - 1] = '\0'; 4723 cmdLine[sizeof(cmdLine) - 2] = '\0'; 4724 snprintf(cmdLine, sizeof(cmdLine) - 1, "\"%s\"", postgres_exec_path); 4725 i = 0; 4726 while (argv[++i] != NULL) 4727 { 4728 j = strlen(cmdLine); 4729 snprintf(cmdLine + j, sizeof(cmdLine) - 1 - j, " \"%s\"", argv[i]); 4730 } 4731 if (cmdLine[sizeof(cmdLine) - 2] != '\0') 4732 { 4733 elog(LOG, "subprocess command line too long"); 4734 return -1; 4735 } 4736 4737 memset(&pi, 0, sizeof(pi)); 4738 memset(&si, 0, sizeof(si)); 4739 si.cb = sizeof(si); 4740 4741 /* 4742 * Create the subprocess in a suspended state. This will be resumed later, 4743 * once we have written out the parameter file. 4744 */ 4745 if (!CreateProcess(NULL, cmdLine, NULL, NULL, TRUE, CREATE_SUSPENDED, 4746 NULL, NULL, &si, &pi)) 4747 { 4748 elog(LOG, "CreateProcess call failed: %m (error code %lu)", 4749 GetLastError()); 4750 return -1; 4751 } 4752 4753 if (!save_backend_variables(param, port, pi.hProcess, pi.dwProcessId)) 4754 { 4755 /* 4756 * log made by save_backend_variables, but we have to clean up the 4757 * mess with the half-started process 4758 */ 4759 if (!TerminateProcess(pi.hProcess, 255)) 4760 ereport(LOG, 4761 (errmsg_internal("could not terminate unstarted process: error code %lu", 4762 GetLastError()))); 4763 CloseHandle(pi.hProcess); 4764 CloseHandle(pi.hThread); 4765 return -1; /* log made by save_backend_variables */ 4766 } 4767 4768 /* Drop the parameter shared memory that is now inherited to the backend */ 4769 if (!UnmapViewOfFile(param)) 4770 elog(LOG, "could not unmap view of backend parameter file: error code %lu", 4771 GetLastError()); 4772 if (!CloseHandle(paramHandle)) 4773 elog(LOG, "could not close handle to backend parameter file: error code %lu", 4774 GetLastError()); 4775 4776 /* 4777 * Reserve the memory region used by our main shared memory segment before 4778 * we resume the child process. Normally this should succeed, but if ASLR 4779 * is active then it might sometimes fail due to the stack or heap having 4780 * gotten mapped into that range. In that case, just terminate the 4781 * process and retry. 4782 */ 4783 if (!pgwin32_ReserveSharedMemoryRegion(pi.hProcess)) 4784 { 4785 /* pgwin32_ReserveSharedMemoryRegion already made a log entry */ 4786 if (!TerminateProcess(pi.hProcess, 255)) 4787 ereport(LOG, 4788 (errmsg_internal("could not terminate process that failed to reserve memory: error code %lu", 4789 GetLastError()))); 4790 CloseHandle(pi.hProcess); 4791 CloseHandle(pi.hThread); 4792 if (++retry_count < 100) 4793 goto retry; 4794 ereport(LOG, 4795 (errmsg("giving up after too many tries to reserve shared memory"), 4796 errhint("This might be caused by ASLR or antivirus software."))); 4797 return -1; 4798 } 4799 4800 /* 4801 * Now that the backend variables are written out, we start the child 4802 * thread so it can start initializing while we set up the rest of the 4803 * parent state. 4804 */ 4805 if (ResumeThread(pi.hThread) == -1) 4806 { 4807 if (!TerminateProcess(pi.hProcess, 255)) 4808 { 4809 ereport(LOG, 4810 (errmsg_internal("could not terminate unstartable process: error code %lu", 4811 GetLastError()))); 4812 CloseHandle(pi.hProcess); 4813 CloseHandle(pi.hThread); 4814 return -1; 4815 } 4816 CloseHandle(pi.hProcess); 4817 CloseHandle(pi.hThread); 4818 ereport(LOG, 4819 (errmsg_internal("could not resume thread of unstarted process: error code %lu", 4820 GetLastError()))); 4821 return -1; 4822 } 4823 4824 /* 4825 * Queue a waiter to signal when this child dies. The wait will be handled 4826 * automatically by an operating system thread pool. 4827 * 4828 * Note: use malloc instead of palloc, since it needs to be thread-safe. 4829 * Struct will be free():d from the callback function that runs on a 4830 * different thread. 4831 */ 4832 childinfo = malloc(sizeof(win32_deadchild_waitinfo)); 4833 if (!childinfo) 4834 ereport(FATAL, 4835 (errcode(ERRCODE_OUT_OF_MEMORY), 4836 errmsg("out of memory"))); 4837 4838 childinfo->procHandle = pi.hProcess; 4839 childinfo->procId = pi.dwProcessId; 4840 4841 if (!RegisterWaitForSingleObject(&childinfo->waitHandle, 4842 pi.hProcess, 4843 pgwin32_deadchild_callback, 4844 childinfo, 4845 INFINITE, 4846 WT_EXECUTEONLYONCE | WT_EXECUTEINWAITTHREAD)) 4847 ereport(FATAL, 4848 (errmsg_internal("could not register process for wait: error code %lu", 4849 GetLastError()))); 4850 4851 /* Don't close pi.hProcess here - the wait thread needs access to it */ 4852 4853 CloseHandle(pi.hThread); 4854 4855 return pi.dwProcessId; 4856 } 4857 #endif /* WIN32 */ 4858 4859 4860 /* 4861 * SubPostmasterMain -- Get the fork/exec'd process into a state equivalent 4862 * to what it would be if we'd simply forked on Unix, and then 4863 * dispatch to the appropriate place. 4864 * 4865 * The first two command line arguments are expected to be "--forkFOO" 4866 * (where FOO indicates which postmaster child we are to become), and 4867 * the name of a variables file that we can read to load data that would 4868 * have been inherited by fork() on Unix. Remaining arguments go to the 4869 * subprocess FooMain() routine. 4870 */ 4871 void 4872 SubPostmasterMain(int argc, char *argv[]) 4873 { 4874 Port port; 4875 4876 /* In EXEC_BACKEND case we will not have inherited these settings */ 4877 IsPostmasterEnvironment = true; 4878 whereToSendOutput = DestNone; 4879 4880 /* Setup as postmaster child */ 4881 InitPostmasterChild(); 4882 4883 /* Setup essential subsystems (to ensure elog() behaves sanely) */ 4884 InitializeGUCOptions(); 4885 4886 /* Check we got appropriate args */ 4887 if (argc < 3) 4888 elog(FATAL, "invalid subpostmaster invocation"); 4889 4890 /* Read in the variables file */ 4891 memset(&port, 0, sizeof(Port)); 4892 read_backend_variables(argv[2], &port); 4893 4894 /* Close the postmaster's sockets (as soon as we know them) */ 4895 ClosePostmasterPorts(strcmp(argv[1], "--forklog") == 0); 4896 4897 /* 4898 * Set reference point for stack-depth checking 4899 */ 4900 set_stack_base(); 4901 4902 /* 4903 * If appropriate, physically re-attach to shared memory segment. We want 4904 * to do this before going any further to ensure that we can attach at the 4905 * same address the postmaster used. On the other hand, if we choose not 4906 * to re-attach, we may have other cleanup to do. 4907 * 4908 * If testing EXEC_BACKEND on Linux, you should run this as root before 4909 * starting the postmaster: 4910 * 4911 * echo 0 >/proc/sys/kernel/randomize_va_space 4912 * 4913 * This prevents using randomized stack and code addresses that cause the 4914 * child process's memory map to be different from the parent's, making it 4915 * sometimes impossible to attach to shared memory at the desired address. 4916 * Return the setting to its old value (usually '1' or '2') when finished. 4917 */ 4918 if (strcmp(argv[1], "--forkbackend") == 0 || 4919 strcmp(argv[1], "--forkavlauncher") == 0 || 4920 strcmp(argv[1], "--forkavworker") == 0 || 4921 strcmp(argv[1], "--forkboot") == 0 || 4922 strncmp(argv[1], "--forkbgworker=", 15) == 0) 4923 PGSharedMemoryReAttach(); 4924 else 4925 PGSharedMemoryNoReAttach(); 4926 4927 /* autovacuum needs this set before calling InitProcess */ 4928 if (strcmp(argv[1], "--forkavlauncher") == 0) 4929 AutovacuumLauncherIAm(); 4930 if (strcmp(argv[1], "--forkavworker") == 0) 4931 AutovacuumWorkerIAm(); 4932 4933 /* 4934 * Start our win32 signal implementation. This has to be done after we 4935 * read the backend variables, because we need to pick up the signal pipe 4936 * from the parent process. 4937 */ 4938 #ifdef WIN32 4939 pgwin32_signal_initialize(); 4940 #endif 4941 4942 /* In EXEC_BACKEND case we will not have inherited these settings */ 4943 pqinitmask(); 4944 PG_SETMASK(&BlockSig); 4945 4946 /* Read in remaining GUC variables */ 4947 read_nondefault_variables(); 4948 4949 /* 4950 * Check that the data directory looks valid, which will also check the 4951 * privileges on the data directory and update our umask and file/group 4952 * variables for creating files later. Note: this should really be done 4953 * before we create any files or directories. 4954 */ 4955 checkDataDir(); 4956 4957 /* 4958 * (re-)read control file, as it contains config. The postmaster will 4959 * already have read this, but this process doesn't know about that. 4960 */ 4961 LocalProcessControlFile(false); 4962 4963 /* 4964 * Reload any libraries that were preloaded by the postmaster. Since we 4965 * exec'd this process, those libraries didn't come along with us; but we 4966 * should load them into all child processes to be consistent with the 4967 * non-EXEC_BACKEND behavior. 4968 */ 4969 process_shared_preload_libraries(); 4970 4971 /* Run backend or appropriate child */ 4972 if (strcmp(argv[1], "--forkbackend") == 0) 4973 { 4974 Assert(argc == 3); /* shouldn't be any more args */ 4975 4976 /* 4977 * Need to reinitialize the SSL library in the backend, since the 4978 * context structures contain function pointers and cannot be passed 4979 * through the parameter file. 4980 * 4981 * If for some reason reload fails (maybe the user installed broken 4982 * key files), soldier on without SSL; that's better than all 4983 * connections becoming impossible. 4984 * 4985 * XXX should we do this in all child processes? For the moment it's 4986 * enough to do it in backend children. 4987 */ 4988 #ifdef USE_SSL 4989 if (EnableSSL) 4990 { 4991 if (secure_initialize(false) == 0) 4992 LoadedSSL = true; 4993 else 4994 ereport(LOG, 4995 (errmsg("SSL configuration could not be loaded in child process"))); 4996 } 4997 #endif 4998 4999 /* 5000 * Perform additional initialization and collect startup packet. 5001 * 5002 * We want to do this before InitProcess() for a couple of reasons: 1. 5003 * so that we aren't eating up a PGPROC slot while waiting on the 5004 * client. 2. so that if InitProcess() fails due to being out of 5005 * PGPROC slots, we have already initialized libpq and are able to 5006 * report the error to the client. 5007 */ 5008 BackendInitialize(&port); 5009 5010 /* Restore basic shared memory pointers */ 5011 InitShmemAccess(UsedShmemSegAddr); 5012 5013 /* Need a PGPROC to run CreateSharedMemoryAndSemaphores */ 5014 InitProcess(); 5015 5016 /* Attach process to shared data structures */ 5017 CreateSharedMemoryAndSemaphores(0); 5018 5019 /* And run the backend */ 5020 BackendRun(&port); /* does not return */ 5021 } 5022 if (strcmp(argv[1], "--forkboot") == 0) 5023 { 5024 /* Restore basic shared memory pointers */ 5025 InitShmemAccess(UsedShmemSegAddr); 5026 5027 /* Need a PGPROC to run CreateSharedMemoryAndSemaphores */ 5028 InitAuxiliaryProcess(); 5029 5030 /* Attach process to shared data structures */ 5031 CreateSharedMemoryAndSemaphores(0); 5032 5033 AuxiliaryProcessMain(argc - 2, argv + 2); /* does not return */ 5034 } 5035 if (strcmp(argv[1], "--forkavlauncher") == 0) 5036 { 5037 /* Restore basic shared memory pointers */ 5038 InitShmemAccess(UsedShmemSegAddr); 5039 5040 /* Need a PGPROC to run CreateSharedMemoryAndSemaphores */ 5041 InitProcess(); 5042 5043 /* Attach process to shared data structures */ 5044 CreateSharedMemoryAndSemaphores(0); 5045 5046 AutoVacLauncherMain(argc - 2, argv + 2); /* does not return */ 5047 } 5048 if (strcmp(argv[1], "--forkavworker") == 0) 5049 { 5050 /* Restore basic shared memory pointers */ 5051 InitShmemAccess(UsedShmemSegAddr); 5052 5053 /* Need a PGPROC to run CreateSharedMemoryAndSemaphores */ 5054 InitProcess(); 5055 5056 /* Attach process to shared data structures */ 5057 CreateSharedMemoryAndSemaphores(0); 5058 5059 AutoVacWorkerMain(argc - 2, argv + 2); /* does not return */ 5060 } 5061 if (strncmp(argv[1], "--forkbgworker=", 15) == 0) 5062 { 5063 int shmem_slot; 5064 5065 /* do this as early as possible; in particular, before InitProcess() */ 5066 IsBackgroundWorker = true; 5067 5068 /* Restore basic shared memory pointers */ 5069 InitShmemAccess(UsedShmemSegAddr); 5070 5071 /* Need a PGPROC to run CreateSharedMemoryAndSemaphores */ 5072 InitProcess(); 5073 5074 /* Attach process to shared data structures */ 5075 CreateSharedMemoryAndSemaphores(0); 5076 5077 /* Fetch MyBgworkerEntry from shared memory */ 5078 shmem_slot = atoi(argv[1] + 15); 5079 MyBgworkerEntry = BackgroundWorkerEntry(shmem_slot); 5080 5081 StartBackgroundWorker(); 5082 } 5083 if (strcmp(argv[1], "--forkarch") == 0) 5084 { 5085 /* Do not want to attach to shared memory */ 5086 5087 PgArchiverMain(argc, argv); /* does not return */ 5088 } 5089 if (strcmp(argv[1], "--forkcol") == 0) 5090 { 5091 /* Do not want to attach to shared memory */ 5092 5093 PgstatCollectorMain(argc, argv); /* does not return */ 5094 } 5095 if (strcmp(argv[1], "--forklog") == 0) 5096 { 5097 /* Do not want to attach to shared memory */ 5098 5099 SysLoggerMain(argc, argv); /* does not return */ 5100 } 5101 5102 abort(); /* shouldn't get here */ 5103 } 5104 #endif /* EXEC_BACKEND */ 5105 5106 5107 /* 5108 * ExitPostmaster -- cleanup 5109 * 5110 * Do NOT call exit() directly --- always go through here! 5111 */ 5112 static void 5113 ExitPostmaster(int status) 5114 { 5115 #ifdef HAVE_PTHREAD_IS_THREADED_NP 5116 5117 /* 5118 * There is no known cause for a postmaster to become multithreaded after 5119 * startup. Recheck to account for the possibility of unknown causes. 5120 * This message uses LOG level, because an unclean shutdown at this point 5121 * would usually not look much different from a clean shutdown. 5122 */ 5123 if (pthread_is_threaded_np() != 0) 5124 ereport(LOG, 5125 (errcode(ERRCODE_INTERNAL_ERROR), 5126 errmsg_internal("postmaster became multithreaded"), 5127 errdetail("Please report this to <pgsql-bugs@lists.postgresql.org>."))); 5128 #endif 5129 5130 /* should cleanup shared memory and kill all backends */ 5131 5132 /* 5133 * Not sure of the semantics here. When the Postmaster dies, should the 5134 * backends all be killed? probably not. 5135 * 5136 * MUST -- vadim 05-10-1999 5137 */ 5138 5139 proc_exit(status); 5140 } 5141 5142 /* 5143 * sigusr1_handler - handle signal conditions from child processes 5144 */ 5145 static void 5146 sigusr1_handler(SIGNAL_ARGS) 5147 { 5148 int save_errno = errno; 5149 5150 /* 5151 * We rely on the signal mechanism to have blocked all signals ... except 5152 * on Windows, which lacks sigaction(), so we have to do it manually. 5153 */ 5154 #ifdef WIN32 5155 PG_SETMASK(&BlockSig); 5156 #endif 5157 5158 /* 5159 * RECOVERY_STARTED and BEGIN_HOT_STANDBY signals are ignored in 5160 * unexpected states. If the startup process quickly starts up, completes 5161 * recovery, exits, we might process the death of the startup process 5162 * first. We don't want to go back to recovery in that case. 5163 */ 5164 if (CheckPostmasterSignal(PMSIGNAL_RECOVERY_STARTED) && 5165 pmState == PM_STARTUP && Shutdown == NoShutdown) 5166 { 5167 /* WAL redo has started. We're out of reinitialization. */ 5168 FatalError = false; 5169 Assert(AbortStartTime == 0); 5170 5171 /* 5172 * Crank up the background tasks. It doesn't matter if this fails, 5173 * we'll just try again later. 5174 */ 5175 Assert(CheckpointerPID == 0); 5176 CheckpointerPID = StartCheckpointer(); 5177 Assert(BgWriterPID == 0); 5178 BgWriterPID = StartBackgroundWriter(); 5179 5180 /* 5181 * Start the archiver if we're responsible for (re-)archiving received 5182 * files. 5183 */ 5184 Assert(PgArchPID == 0); 5185 if (XLogArchivingAlways()) 5186 PgArchPID = pgarch_start(); 5187 5188 /* 5189 * If we aren't planning to enter hot standby mode later, treat 5190 * RECOVERY_STARTED as meaning we're out of startup, and report status 5191 * accordingly. 5192 */ 5193 if (!EnableHotStandby) 5194 { 5195 AddToDataDirLockFile(LOCK_FILE_LINE_PM_STATUS, PM_STATUS_STANDBY); 5196 #ifdef USE_SYSTEMD 5197 sd_notify(0, "READY=1"); 5198 #endif 5199 } 5200 5201 pmState = PM_RECOVERY; 5202 } 5203 5204 if (CheckPostmasterSignal(PMSIGNAL_BEGIN_HOT_STANDBY) && 5205 pmState == PM_RECOVERY && Shutdown == NoShutdown) 5206 { 5207 /* 5208 * Likewise, start other special children as needed. 5209 */ 5210 Assert(PgStatPID == 0); 5211 PgStatPID = pgstat_start(); 5212 5213 ereport(LOG, 5214 (errmsg("database system is ready to accept read only connections"))); 5215 5216 /* Report status */ 5217 AddToDataDirLockFile(LOCK_FILE_LINE_PM_STATUS, PM_STATUS_READY); 5218 #ifdef USE_SYSTEMD 5219 sd_notify(0, "READY=1"); 5220 #endif 5221 5222 pmState = PM_HOT_STANDBY; 5223 connsAllowed = ALLOW_ALL_CONNS; 5224 5225 /* Some workers may be scheduled to start now */ 5226 StartWorkerNeeded = true; 5227 } 5228 5229 /* Process background worker state changes. */ 5230 if (CheckPostmasterSignal(PMSIGNAL_BACKGROUND_WORKER_CHANGE)) 5231 { 5232 /* Accept new worker requests only if not stopping. */ 5233 BackgroundWorkerStateChange(pmState < PM_STOP_BACKENDS); 5234 StartWorkerNeeded = true; 5235 } 5236 5237 if (StartWorkerNeeded || HaveCrashedWorker) 5238 maybe_start_bgworkers(); 5239 5240 if (CheckPostmasterSignal(PMSIGNAL_WAKEN_ARCHIVER) && 5241 PgArchPID != 0) 5242 { 5243 /* 5244 * Send SIGUSR1 to archiver process, to wake it up and begin archiving 5245 * next WAL file. 5246 */ 5247 signal_child(PgArchPID, SIGUSR1); 5248 } 5249 5250 /* Tell syslogger to rotate logfile if requested */ 5251 if (SysLoggerPID != 0) 5252 { 5253 if (CheckLogrotateSignal()) 5254 { 5255 signal_child(SysLoggerPID, SIGUSR1); 5256 RemoveLogrotateSignalFiles(); 5257 } 5258 else if (CheckPostmasterSignal(PMSIGNAL_ROTATE_LOGFILE)) 5259 { 5260 signal_child(SysLoggerPID, SIGUSR1); 5261 } 5262 } 5263 5264 if (CheckPostmasterSignal(PMSIGNAL_START_AUTOVAC_LAUNCHER) && 5265 Shutdown <= SmartShutdown && pmState < PM_STOP_BACKENDS) 5266 { 5267 /* 5268 * Start one iteration of the autovacuum daemon, even if autovacuuming 5269 * is nominally not enabled. This is so we can have an active defense 5270 * against transaction ID wraparound. We set a flag for the main loop 5271 * to do it rather than trying to do it here --- this is because the 5272 * autovac process itself may send the signal, and we want to handle 5273 * that by launching another iteration as soon as the current one 5274 * completes. 5275 */ 5276 start_autovac_launcher = true; 5277 } 5278 5279 if (CheckPostmasterSignal(PMSIGNAL_START_AUTOVAC_WORKER) && 5280 Shutdown <= SmartShutdown && pmState < PM_STOP_BACKENDS) 5281 { 5282 /* The autovacuum launcher wants us to start a worker process. */ 5283 StartAutovacuumWorker(); 5284 } 5285 5286 if (CheckPostmasterSignal(PMSIGNAL_START_WALRECEIVER)) 5287 { 5288 /* Startup Process wants us to start the walreceiver process. */ 5289 /* Start immediately if possible, else remember request for later. */ 5290 WalReceiverRequested = true; 5291 MaybeStartWalReceiver(); 5292 } 5293 5294 /* 5295 * Try to advance postmaster's state machine, if a child requests it. 5296 * 5297 * Be careful about the order of this action relative to sigusr1_handler's 5298 * other actions. Generally, this should be after other actions, in case 5299 * they have effects PostmasterStateMachine would need to know about. 5300 * However, we should do it before the CheckPromoteSignal step, which 5301 * cannot have any (immediate) effect on the state machine, but does 5302 * depend on what state we're in now. 5303 */ 5304 if (CheckPostmasterSignal(PMSIGNAL_ADVANCE_STATE_MACHINE)) 5305 { 5306 PostmasterStateMachine(); 5307 } 5308 5309 if (StartupPID != 0 && 5310 (pmState == PM_STARTUP || pmState == PM_RECOVERY || 5311 pmState == PM_HOT_STANDBY) && 5312 CheckPromoteSignal()) 5313 { 5314 /* Tell startup process to finish recovery */ 5315 signal_child(StartupPID, SIGUSR2); 5316 } 5317 5318 #ifdef WIN32 5319 PG_SETMASK(&UnBlockSig); 5320 #endif 5321 5322 errno = save_errno; 5323 } 5324 5325 /* 5326 * SIGTERM while processing startup packet. 5327 * Clean up and exit(1). 5328 * 5329 * Running proc_exit() from a signal handler is pretty unsafe, since we 5330 * can't know what code we've interrupted. But the alternative of using 5331 * _exit(2) is also unpalatable, since it'd mean that a "fast shutdown" 5332 * would cause a database crash cycle (forcing WAL replay at restart) 5333 * if any sessions are in authentication. So we live with it for now. 5334 * 5335 * One might be tempted to try to send a message indicating why we are 5336 * disconnecting. However, that would make this even more unsafe. Also, 5337 * it seems undesirable to provide clues about the database's state to 5338 * a client that has not yet completed authentication. 5339 */ 5340 static void 5341 process_startup_packet_die(SIGNAL_ARGS) 5342 { 5343 proc_exit(1); 5344 } 5345 5346 /* 5347 * SIGQUIT while processing startup packet. 5348 * 5349 * Some backend has bought the farm, 5350 * so we need to stop what we're doing and exit. 5351 */ 5352 static void 5353 process_startup_packet_quickdie(SIGNAL_ARGS) 5354 { 5355 /* 5356 * We DO NOT want to run proc_exit() or atexit() callbacks; they wouldn't 5357 * be safe to run from a signal handler. Just nail the windows shut and 5358 * get out of town. 5359 * 5360 * Note we do _exit(2) not _exit(1). This is to force the postmaster into 5361 * a system reset cycle if someone sends a manual SIGQUIT to a random 5362 * backend. (While it might be safe to do _exit(1), since this session 5363 * shouldn't have touched shared memory yet, there seems little point in 5364 * taking any risks.) 5365 */ 5366 _exit(2); 5367 } 5368 5369 /* 5370 * Dummy signal handler 5371 * 5372 * We use this for signals that we don't actually use in the postmaster, 5373 * but we do use in backends. If we were to SIG_IGN such signals in the 5374 * postmaster, then a newly started backend might drop a signal that arrives 5375 * before it's able to reconfigure its signal processing. (See notes in 5376 * tcop/postgres.c.) 5377 */ 5378 static void 5379 dummy_handler(SIGNAL_ARGS) 5380 { 5381 } 5382 5383 /* 5384 * Timeout while processing startup packet. 5385 * As for process_startup_packet_die(), we clean up and exit(1). 5386 * 5387 * This is theoretically just as hazardous as in process_startup_packet_die(), 5388 * although in practice we're almost certainly waiting for client input, 5389 * which greatly reduces the risk. 5390 */ 5391 static void 5392 StartupPacketTimeoutHandler(void) 5393 { 5394 proc_exit(1); 5395 } 5396 5397 5398 /* 5399 * Generate a random cancel key. 5400 */ 5401 static bool 5402 RandomCancelKey(int32 *cancel_key) 5403 { 5404 return pg_strong_random(cancel_key, sizeof(int32)); 5405 } 5406 5407 /* 5408 * Count up number of child processes of specified types (dead_end children 5409 * are always excluded). 5410 */ 5411 static int 5412 CountChildren(int target) 5413 { 5414 dlist_iter iter; 5415 int cnt = 0; 5416 5417 dlist_foreach(iter, &BackendList) 5418 { 5419 Backend *bp = dlist_container(Backend, elem, iter.cur); 5420 5421 if (bp->dead_end) 5422 continue; 5423 5424 /* 5425 * Since target == BACKEND_TYPE_ALL is the most common case, we test 5426 * it first and avoid touching shared memory for every child. 5427 */ 5428 if (target != BACKEND_TYPE_ALL) 5429 { 5430 /* 5431 * Assign bkend_type for any recently announced WAL Sender 5432 * processes. 5433 */ 5434 if (bp->bkend_type == BACKEND_TYPE_NORMAL && 5435 IsPostmasterChildWalSender(bp->child_slot)) 5436 bp->bkend_type = BACKEND_TYPE_WALSND; 5437 5438 if (!(target & bp->bkend_type)) 5439 continue; 5440 } 5441 5442 cnt++; 5443 } 5444 return cnt; 5445 } 5446 5447 5448 /* 5449 * StartChildProcess -- start an auxiliary process for the postmaster 5450 * 5451 * "type" determines what kind of child will be started. All child types 5452 * initially go to AuxiliaryProcessMain, which will handle common setup. 5453 * 5454 * Return value of StartChildProcess is subprocess' PID, or 0 if failed 5455 * to start subprocess. 5456 */ 5457 static pid_t 5458 StartChildProcess(AuxProcType type) 5459 { 5460 pid_t pid; 5461 char *av[10]; 5462 int ac = 0; 5463 char typebuf[32]; 5464 5465 /* 5466 * Set up command-line arguments for subprocess 5467 */ 5468 av[ac++] = "postgres"; 5469 5470 #ifdef EXEC_BACKEND 5471 av[ac++] = "--forkboot"; 5472 av[ac++] = NULL; /* filled in by postmaster_forkexec */ 5473 #endif 5474 5475 snprintf(typebuf, sizeof(typebuf), "-x%d", type); 5476 av[ac++] = typebuf; 5477 5478 av[ac] = NULL; 5479 Assert(ac < lengthof(av)); 5480 5481 #ifdef EXEC_BACKEND 5482 pid = postmaster_forkexec(ac, av); 5483 #else /* !EXEC_BACKEND */ 5484 pid = fork_process(); 5485 5486 if (pid == 0) /* child */ 5487 { 5488 InitPostmasterChild(); 5489 5490 /* Close the postmaster's sockets */ 5491 ClosePostmasterPorts(false); 5492 5493 /* Release postmaster's working memory context */ 5494 MemoryContextSwitchTo(TopMemoryContext); 5495 MemoryContextDelete(PostmasterContext); 5496 PostmasterContext = NULL; 5497 5498 AuxiliaryProcessMain(ac, av); 5499 ExitPostmaster(0); 5500 } 5501 #endif /* EXEC_BACKEND */ 5502 5503 if (pid < 0) 5504 { 5505 /* in parent, fork failed */ 5506 int save_errno = errno; 5507 5508 errno = save_errno; 5509 switch (type) 5510 { 5511 case StartupProcess: 5512 ereport(LOG, 5513 (errmsg("could not fork startup process: %m"))); 5514 break; 5515 case BgWriterProcess: 5516 ereport(LOG, 5517 (errmsg("could not fork background writer process: %m"))); 5518 break; 5519 case CheckpointerProcess: 5520 ereport(LOG, 5521 (errmsg("could not fork checkpointer process: %m"))); 5522 break; 5523 case WalWriterProcess: 5524 ereport(LOG, 5525 (errmsg("could not fork WAL writer process: %m"))); 5526 break; 5527 case WalReceiverProcess: 5528 ereport(LOG, 5529 (errmsg("could not fork WAL receiver process: %m"))); 5530 break; 5531 default: 5532 ereport(LOG, 5533 (errmsg("could not fork process: %m"))); 5534 break; 5535 } 5536 5537 /* 5538 * fork failure is fatal during startup, but there's no need to choke 5539 * immediately if starting other child types fails. 5540 */ 5541 if (type == StartupProcess) 5542 ExitPostmaster(1); 5543 return 0; 5544 } 5545 5546 /* 5547 * in parent, successful fork 5548 */ 5549 return pid; 5550 } 5551 5552 /* 5553 * StartAutovacuumWorker 5554 * Start an autovac worker process. 5555 * 5556 * This function is here because it enters the resulting PID into the 5557 * postmaster's private backends list. 5558 * 5559 * NB -- this code very roughly matches BackendStartup. 5560 */ 5561 static void 5562 StartAutovacuumWorker(void) 5563 { 5564 Backend *bn; 5565 5566 /* 5567 * If not in condition to run a process, don't try, but handle it like a 5568 * fork failure. This does not normally happen, since the signal is only 5569 * supposed to be sent by autovacuum launcher when it's OK to do it, but 5570 * we have to check to avoid race-condition problems during DB state 5571 * changes. 5572 */ 5573 if (canAcceptConnections(BACKEND_TYPE_AUTOVAC) == CAC_OK) 5574 { 5575 /* 5576 * Compute the cancel key that will be assigned to this session. We 5577 * probably don't need cancel keys for autovac workers, but we'd 5578 * better have something random in the field to prevent unfriendly 5579 * people from sending cancels to them. 5580 */ 5581 if (!RandomCancelKey(&MyCancelKey)) 5582 { 5583 ereport(LOG, 5584 (errcode(ERRCODE_INTERNAL_ERROR), 5585 errmsg("could not generate random cancel key"))); 5586 return; 5587 } 5588 5589 bn = (Backend *) malloc(sizeof(Backend)); 5590 if (bn) 5591 { 5592 bn->cancel_key = MyCancelKey; 5593 5594 /* Autovac workers are not dead_end and need a child slot */ 5595 bn->dead_end = false; 5596 bn->child_slot = MyPMChildSlot = AssignPostmasterChildSlot(); 5597 bn->bgworker_notify = false; 5598 5599 bn->pid = StartAutoVacWorker(); 5600 if (bn->pid > 0) 5601 { 5602 bn->bkend_type = BACKEND_TYPE_AUTOVAC; 5603 dlist_push_head(&BackendList, &bn->elem); 5604 #ifdef EXEC_BACKEND 5605 ShmemBackendArrayAdd(bn); 5606 #endif 5607 /* all OK */ 5608 return; 5609 } 5610 5611 /* 5612 * fork failed, fall through to report -- actual error message was 5613 * logged by StartAutoVacWorker 5614 */ 5615 (void) ReleasePostmasterChildSlot(bn->child_slot); 5616 free(bn); 5617 } 5618 else 5619 ereport(LOG, 5620 (errcode(ERRCODE_OUT_OF_MEMORY), 5621 errmsg("out of memory"))); 5622 } 5623 5624 /* 5625 * Report the failure to the launcher, if it's running. (If it's not, we 5626 * might not even be connected to shared memory, so don't try to call 5627 * AutoVacWorkerFailed.) Note that we also need to signal it so that it 5628 * responds to the condition, but we don't do that here, instead waiting 5629 * for ServerLoop to do it. This way we avoid a ping-pong signalling in 5630 * quick succession between the autovac launcher and postmaster in case 5631 * things get ugly. 5632 */ 5633 if (AutoVacPID != 0) 5634 { 5635 AutoVacWorkerFailed(); 5636 avlauncher_needs_signal = true; 5637 } 5638 } 5639 5640 /* 5641 * MaybeStartWalReceiver 5642 * Start the WAL receiver process, if not running and our state allows. 5643 * 5644 * Note: if WalReceiverPID is already nonzero, it might seem that we should 5645 * clear WalReceiverRequested. However, there's a race condition if the 5646 * walreceiver terminates and the startup process immediately requests a new 5647 * one: it's quite possible to get the signal for the request before reaping 5648 * the dead walreceiver process. Better to risk launching an extra 5649 * walreceiver than to miss launching one we need. (The walreceiver code 5650 * has logic to recognize that it should go away if not needed.) 5651 */ 5652 static void 5653 MaybeStartWalReceiver(void) 5654 { 5655 if (WalReceiverPID == 0 && 5656 (pmState == PM_STARTUP || pmState == PM_RECOVERY || 5657 pmState == PM_HOT_STANDBY) && 5658 Shutdown <= SmartShutdown) 5659 { 5660 WalReceiverPID = StartWalReceiver(); 5661 if (WalReceiverPID != 0) 5662 WalReceiverRequested = false; 5663 /* else leave the flag set, so we'll try again later */ 5664 } 5665 } 5666 5667 5668 /* 5669 * Create the opts file 5670 */ 5671 static bool 5672 CreateOptsFile(int argc, char *argv[], char *fullprogname) 5673 { 5674 FILE *fp; 5675 int i; 5676 5677 #define OPTS_FILE "postmaster.opts" 5678 5679 if ((fp = fopen(OPTS_FILE, "w")) == NULL) 5680 { 5681 elog(LOG, "could not create file \"%s\": %m", OPTS_FILE); 5682 return false; 5683 } 5684 5685 fprintf(fp, "%s", fullprogname); 5686 for (i = 1; i < argc; i++) 5687 fprintf(fp, " \"%s\"", argv[i]); 5688 fputs("\n", fp); 5689 5690 if (fclose(fp)) 5691 { 5692 elog(LOG, "could not write file \"%s\": %m", OPTS_FILE); 5693 return false; 5694 } 5695 5696 return true; 5697 } 5698 5699 5700 /* 5701 * MaxLivePostmasterChildren 5702 * 5703 * This reports the number of entries needed in per-child-process arrays 5704 * (the PMChildFlags array, and if EXEC_BACKEND the ShmemBackendArray). 5705 * These arrays include regular backends, autovac workers, walsenders 5706 * and background workers, but not special children nor dead_end children. 5707 * This allows the arrays to have a fixed maximum size, to wit the same 5708 * too-many-children limit enforced by canAcceptConnections(). The exact value 5709 * isn't too critical as long as it's more than MaxBackends. 5710 */ 5711 int 5712 MaxLivePostmasterChildren(void) 5713 { 5714 return 2 * (MaxConnections + autovacuum_max_workers + 1 + 5715 max_wal_senders + max_worker_processes); 5716 } 5717 5718 /* 5719 * Connect background worker to a database. 5720 */ 5721 void 5722 BackgroundWorkerInitializeConnection(const char *dbname, const char *username, uint32 flags) 5723 { 5724 BackgroundWorker *worker = MyBgworkerEntry; 5725 5726 /* XXX is this the right errcode? */ 5727 if (!(worker->bgw_flags & BGWORKER_BACKEND_DATABASE_CONNECTION)) 5728 ereport(FATAL, 5729 (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED), 5730 errmsg("database connection requirement not indicated during registration"))); 5731 5732 InitPostgres(dbname, InvalidOid, username, InvalidOid, NULL, (flags & BGWORKER_BYPASS_ALLOWCONN) != 0); 5733 5734 /* it had better not gotten out of "init" mode yet */ 5735 if (!IsInitProcessingMode()) 5736 ereport(ERROR, 5737 (errmsg("invalid processing mode in background worker"))); 5738 SetProcessingMode(NormalProcessing); 5739 } 5740 5741 /* 5742 * Connect background worker to a database using OIDs. 5743 */ 5744 void 5745 BackgroundWorkerInitializeConnectionByOid(Oid dboid, Oid useroid, uint32 flags) 5746 { 5747 BackgroundWorker *worker = MyBgworkerEntry; 5748 5749 /* XXX is this the right errcode? */ 5750 if (!(worker->bgw_flags & BGWORKER_BACKEND_DATABASE_CONNECTION)) 5751 ereport(FATAL, 5752 (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED), 5753 errmsg("database connection requirement not indicated during registration"))); 5754 5755 InitPostgres(NULL, dboid, NULL, useroid, NULL, (flags & BGWORKER_BYPASS_ALLOWCONN) != 0); 5756 5757 /* it had better not gotten out of "init" mode yet */ 5758 if (!IsInitProcessingMode()) 5759 ereport(ERROR, 5760 (errmsg("invalid processing mode in background worker"))); 5761 SetProcessingMode(NormalProcessing); 5762 } 5763 5764 /* 5765 * Block/unblock signals in a background worker 5766 */ 5767 void 5768 BackgroundWorkerBlockSignals(void) 5769 { 5770 PG_SETMASK(&BlockSig); 5771 } 5772 5773 void 5774 BackgroundWorkerUnblockSignals(void) 5775 { 5776 PG_SETMASK(&UnBlockSig); 5777 } 5778 5779 #ifdef EXEC_BACKEND 5780 static pid_t 5781 bgworker_forkexec(int shmem_slot) 5782 { 5783 char *av[10]; 5784 int ac = 0; 5785 char forkav[MAXPGPATH]; 5786 5787 snprintf(forkav, MAXPGPATH, "--forkbgworker=%d", shmem_slot); 5788 5789 av[ac++] = "postgres"; 5790 av[ac++] = forkav; 5791 av[ac++] = NULL; /* filled in by postmaster_forkexec */ 5792 av[ac] = NULL; 5793 5794 Assert(ac < lengthof(av)); 5795 5796 return postmaster_forkexec(ac, av); 5797 } 5798 #endif 5799 5800 /* 5801 * Start a new bgworker. 5802 * Starting time conditions must have been checked already. 5803 * 5804 * Returns true on success, false on failure. 5805 * In either case, update the RegisteredBgWorker's state appropriately. 5806 * 5807 * This code is heavily based on autovacuum.c, q.v. 5808 */ 5809 static bool 5810 do_start_bgworker(RegisteredBgWorker *rw) 5811 { 5812 pid_t worker_pid; 5813 5814 Assert(rw->rw_pid == 0); 5815 5816 /* 5817 * Allocate and assign the Backend element. Note we must do this before 5818 * forking, so that we can handle failures (out of memory or child-process 5819 * slots) cleanly. 5820 * 5821 * Treat failure as though the worker had crashed. That way, the 5822 * postmaster will wait a bit before attempting to start it again; if we 5823 * tried again right away, most likely we'd find ourselves hitting the 5824 * same resource-exhaustion condition. 5825 */ 5826 if (!assign_backendlist_entry(rw)) 5827 { 5828 rw->rw_crashed_at = GetCurrentTimestamp(); 5829 return false; 5830 } 5831 5832 ereport(DEBUG1, 5833 (errmsg("starting background worker process \"%s\"", 5834 rw->rw_worker.bgw_name))); 5835 5836 #ifdef EXEC_BACKEND 5837 switch ((worker_pid = bgworker_forkexec(rw->rw_shmem_slot))) 5838 #else 5839 switch ((worker_pid = fork_process())) 5840 #endif 5841 { 5842 case -1: 5843 /* in postmaster, fork failed ... */ 5844 ereport(LOG, 5845 (errmsg("could not fork worker process: %m"))); 5846 /* undo what assign_backendlist_entry did */ 5847 ReleasePostmasterChildSlot(rw->rw_child_slot); 5848 rw->rw_child_slot = 0; 5849 free(rw->rw_backend); 5850 rw->rw_backend = NULL; 5851 /* mark entry as crashed, so we'll try again later */ 5852 rw->rw_crashed_at = GetCurrentTimestamp(); 5853 break; 5854 5855 #ifndef EXEC_BACKEND 5856 case 0: 5857 /* in postmaster child ... */ 5858 InitPostmasterChild(); 5859 5860 /* Close the postmaster's sockets */ 5861 ClosePostmasterPorts(false); 5862 5863 /* 5864 * Before blowing away PostmasterContext, save this bgworker's 5865 * data where it can find it. 5866 */ 5867 MyBgworkerEntry = (BackgroundWorker *) 5868 MemoryContextAlloc(TopMemoryContext, sizeof(BackgroundWorker)); 5869 memcpy(MyBgworkerEntry, &rw->rw_worker, sizeof(BackgroundWorker)); 5870 5871 /* Release postmaster's working memory context */ 5872 MemoryContextSwitchTo(TopMemoryContext); 5873 MemoryContextDelete(PostmasterContext); 5874 PostmasterContext = NULL; 5875 5876 StartBackgroundWorker(); 5877 5878 exit(1); /* should not get here */ 5879 break; 5880 #endif 5881 default: 5882 /* in postmaster, fork successful ... */ 5883 rw->rw_pid = worker_pid; 5884 rw->rw_backend->pid = rw->rw_pid; 5885 ReportBackgroundWorkerPID(rw); 5886 /* add new worker to lists of backends */ 5887 dlist_push_head(&BackendList, &rw->rw_backend->elem); 5888 #ifdef EXEC_BACKEND 5889 ShmemBackendArrayAdd(rw->rw_backend); 5890 #endif 5891 return true; 5892 } 5893 5894 return false; 5895 } 5896 5897 /* 5898 * Does the current postmaster state require starting a worker with the 5899 * specified start_time? 5900 */ 5901 static bool 5902 bgworker_should_start_now(BgWorkerStartTime start_time) 5903 { 5904 switch (pmState) 5905 { 5906 case PM_NO_CHILDREN: 5907 case PM_WAIT_DEAD_END: 5908 case PM_SHUTDOWN_2: 5909 case PM_SHUTDOWN: 5910 case PM_WAIT_BACKENDS: 5911 case PM_STOP_BACKENDS: 5912 break; 5913 5914 case PM_RUN: 5915 if (start_time == BgWorkerStart_RecoveryFinished) 5916 return true; 5917 /* fall through */ 5918 5919 case PM_HOT_STANDBY: 5920 if (start_time == BgWorkerStart_ConsistentState) 5921 return true; 5922 /* fall through */ 5923 5924 case PM_RECOVERY: 5925 case PM_STARTUP: 5926 case PM_INIT: 5927 if (start_time == BgWorkerStart_PostmasterStart) 5928 return true; 5929 /* fall through */ 5930 5931 } 5932 5933 return false; 5934 } 5935 5936 /* 5937 * Allocate the Backend struct for a connected background worker, but don't 5938 * add it to the list of backends just yet. 5939 * 5940 * On failure, return false without changing any worker state. 5941 * 5942 * Some info from the Backend is copied into the passed rw. 5943 */ 5944 static bool 5945 assign_backendlist_entry(RegisteredBgWorker *rw) 5946 { 5947 Backend *bn; 5948 5949 /* 5950 * Check that database state allows another connection. Currently the 5951 * only possible failure is CAC_TOOMANY, so we just log an error message 5952 * based on that rather than checking the error code precisely. 5953 */ 5954 if (canAcceptConnections(BACKEND_TYPE_BGWORKER) != CAC_OK) 5955 { 5956 ereport(LOG, 5957 (errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED), 5958 errmsg("no slot available for new worker process"))); 5959 return false; 5960 } 5961 5962 /* 5963 * Compute the cancel key that will be assigned to this session. We 5964 * probably don't need cancel keys for background workers, but we'd better 5965 * have something random in the field to prevent unfriendly people from 5966 * sending cancels to them. 5967 */ 5968 if (!RandomCancelKey(&MyCancelKey)) 5969 { 5970 ereport(LOG, 5971 (errcode(ERRCODE_INTERNAL_ERROR), 5972 errmsg("could not generate random cancel key"))); 5973 return false; 5974 } 5975 5976 bn = malloc(sizeof(Backend)); 5977 if (bn == NULL) 5978 { 5979 ereport(LOG, 5980 (errcode(ERRCODE_OUT_OF_MEMORY), 5981 errmsg("out of memory"))); 5982 return false; 5983 } 5984 5985 bn->cancel_key = MyCancelKey; 5986 bn->child_slot = MyPMChildSlot = AssignPostmasterChildSlot(); 5987 bn->bkend_type = BACKEND_TYPE_BGWORKER; 5988 bn->dead_end = false; 5989 bn->bgworker_notify = false; 5990 5991 rw->rw_backend = bn; 5992 rw->rw_child_slot = bn->child_slot; 5993 5994 return true; 5995 } 5996 5997 /* 5998 * If the time is right, start background worker(s). 5999 * 6000 * As a side effect, the bgworker control variables are set or reset 6001 * depending on whether more workers may need to be started. 6002 * 6003 * We limit the number of workers started per call, to avoid consuming the 6004 * postmaster's attention for too long when many such requests are pending. 6005 * As long as StartWorkerNeeded is true, ServerLoop will not block and will 6006 * call this function again after dealing with any other issues. 6007 */ 6008 static void 6009 maybe_start_bgworkers(void) 6010 { 6011 #define MAX_BGWORKERS_TO_LAUNCH 100 6012 int num_launched = 0; 6013 TimestampTz now = 0; 6014 slist_mutable_iter iter; 6015 6016 /* 6017 * During crash recovery, we have no need to be called until the state 6018 * transition out of recovery. 6019 */ 6020 if (FatalError) 6021 { 6022 StartWorkerNeeded = false; 6023 HaveCrashedWorker = false; 6024 return; 6025 } 6026 6027 /* Don't need to be called again unless we find a reason for it below */ 6028 StartWorkerNeeded = false; 6029 HaveCrashedWorker = false; 6030 6031 slist_foreach_modify(iter, &BackgroundWorkerList) 6032 { 6033 RegisteredBgWorker *rw; 6034 6035 rw = slist_container(RegisteredBgWorker, rw_lnode, iter.cur); 6036 6037 /* ignore if already running */ 6038 if (rw->rw_pid != 0) 6039 continue; 6040 6041 /* if marked for death, clean up and remove from list */ 6042 if (rw->rw_terminate) 6043 { 6044 ForgetBackgroundWorker(&iter); 6045 continue; 6046 } 6047 6048 /* 6049 * If this worker has crashed previously, maybe it needs to be 6050 * restarted (unless on registration it specified it doesn't want to 6051 * be restarted at all). Check how long ago did a crash last happen. 6052 * If the last crash is too recent, don't start it right away; let it 6053 * be restarted once enough time has passed. 6054 */ 6055 if (rw->rw_crashed_at != 0) 6056 { 6057 if (rw->rw_worker.bgw_restart_time == BGW_NEVER_RESTART) 6058 { 6059 int notify_pid; 6060 6061 notify_pid = rw->rw_worker.bgw_notify_pid; 6062 6063 ForgetBackgroundWorker(&iter); 6064 6065 /* Report worker is gone now. */ 6066 if (notify_pid != 0) 6067 kill(notify_pid, SIGUSR1); 6068 6069 continue; 6070 } 6071 6072 /* read system time only when needed */ 6073 if (now == 0) 6074 now = GetCurrentTimestamp(); 6075 6076 if (!TimestampDifferenceExceeds(rw->rw_crashed_at, now, 6077 rw->rw_worker.bgw_restart_time * 1000)) 6078 { 6079 /* Set flag to remember that we have workers to start later */ 6080 HaveCrashedWorker = true; 6081 continue; 6082 } 6083 } 6084 6085 if (bgworker_should_start_now(rw->rw_worker.bgw_start_time)) 6086 { 6087 /* reset crash time before trying to start worker */ 6088 rw->rw_crashed_at = 0; 6089 6090 /* 6091 * Try to start the worker. 6092 * 6093 * On failure, give up processing workers for now, but set 6094 * StartWorkerNeeded so we'll come back here on the next iteration 6095 * of ServerLoop to try again. (We don't want to wait, because 6096 * there might be additional ready-to-run workers.) We could set 6097 * HaveCrashedWorker as well, since this worker is now marked 6098 * crashed, but there's no need because the next run of this 6099 * function will do that. 6100 */ 6101 if (!do_start_bgworker(rw)) 6102 { 6103 StartWorkerNeeded = true; 6104 return; 6105 } 6106 6107 /* 6108 * If we've launched as many workers as allowed, quit, but have 6109 * ServerLoop call us again to look for additional ready-to-run 6110 * workers. There might not be any, but we'll find out the next 6111 * time we run. 6112 */ 6113 if (++num_launched >= MAX_BGWORKERS_TO_LAUNCH) 6114 { 6115 StartWorkerNeeded = true; 6116 return; 6117 } 6118 } 6119 } 6120 } 6121 6122 /* 6123 * When a backend asks to be notified about worker state changes, we 6124 * set a flag in its backend entry. The background worker machinery needs 6125 * to know when such backends exit. 6126 */ 6127 bool 6128 PostmasterMarkPIDForWorkerNotify(int pid) 6129 { 6130 dlist_iter iter; 6131 Backend *bp; 6132 6133 dlist_foreach(iter, &BackendList) 6134 { 6135 bp = dlist_container(Backend, elem, iter.cur); 6136 if (bp->pid == pid) 6137 { 6138 bp->bgworker_notify = true; 6139 return true; 6140 } 6141 } 6142 return false; 6143 } 6144 6145 #ifdef EXEC_BACKEND 6146 6147 /* 6148 * The following need to be available to the save/restore_backend_variables 6149 * functions. They are marked NON_EXEC_STATIC in their home modules. 6150 */ 6151 extern slock_t *ShmemLock; 6152 extern slock_t *ProcStructLock; 6153 extern PGPROC *AuxiliaryProcs; 6154 extern PMSignalData *PMSignalState; 6155 extern pgsocket pgStatSock; 6156 extern pg_time_t first_syslogger_file_time; 6157 6158 #ifndef WIN32 6159 #define write_inheritable_socket(dest, src, childpid) ((*(dest) = (src)), true) 6160 #define read_inheritable_socket(dest, src) (*(dest) = *(src)) 6161 #else 6162 static bool write_duplicated_handle(HANDLE *dest, HANDLE src, HANDLE child); 6163 static bool write_inheritable_socket(InheritableSocket *dest, SOCKET src, 6164 pid_t childPid); 6165 static void read_inheritable_socket(SOCKET *dest, InheritableSocket *src); 6166 #endif 6167 6168 6169 /* Save critical backend variables into the BackendParameters struct */ 6170 #ifndef WIN32 6171 static bool 6172 save_backend_variables(BackendParameters *param, Port *port) 6173 #else 6174 static bool 6175 save_backend_variables(BackendParameters *param, Port *port, 6176 HANDLE childProcess, pid_t childPid) 6177 #endif 6178 { 6179 memcpy(¶m->port, port, sizeof(Port)); 6180 if (!write_inheritable_socket(¶m->portsocket, port->sock, childPid)) 6181 return false; 6182 6183 strlcpy(param->DataDir, DataDir, MAXPGPATH); 6184 6185 memcpy(¶m->ListenSocket, &ListenSocket, sizeof(ListenSocket)); 6186 6187 param->MyCancelKey = MyCancelKey; 6188 param->MyPMChildSlot = MyPMChildSlot; 6189 6190 #ifdef WIN32 6191 param->ShmemProtectiveRegion = ShmemProtectiveRegion; 6192 #endif 6193 param->UsedShmemSegID = UsedShmemSegID; 6194 param->UsedShmemSegAddr = UsedShmemSegAddr; 6195 6196 param->ShmemLock = ShmemLock; 6197 param->ShmemVariableCache = ShmemVariableCache; 6198 param->ShmemBackendArray = ShmemBackendArray; 6199 6200 #ifndef HAVE_SPINLOCKS 6201 param->SpinlockSemaArray = SpinlockSemaArray; 6202 #endif 6203 param->NamedLWLockTrancheRequests = NamedLWLockTrancheRequests; 6204 param->NamedLWLockTrancheArray = NamedLWLockTrancheArray; 6205 param->MainLWLockArray = MainLWLockArray; 6206 param->ProcStructLock = ProcStructLock; 6207 param->ProcGlobal = ProcGlobal; 6208 param->AuxiliaryProcs = AuxiliaryProcs; 6209 param->PreparedXactProcs = PreparedXactProcs; 6210 param->PMSignalState = PMSignalState; 6211 if (!write_inheritable_socket(¶m->pgStatSock, pgStatSock, childPid)) 6212 return false; 6213 6214 param->PostmasterPid = PostmasterPid; 6215 param->PgStartTime = PgStartTime; 6216 param->PgReloadTime = PgReloadTime; 6217 param->first_syslogger_file_time = first_syslogger_file_time; 6218 6219 param->redirection_done = redirection_done; 6220 param->IsBinaryUpgrade = IsBinaryUpgrade; 6221 param->max_safe_fds = max_safe_fds; 6222 6223 param->MaxBackends = MaxBackends; 6224 6225 #ifdef WIN32 6226 param->PostmasterHandle = PostmasterHandle; 6227 if (!write_duplicated_handle(¶m->initial_signal_pipe, 6228 pgwin32_create_signal_listener(childPid), 6229 childProcess)) 6230 return false; 6231 #else 6232 memcpy(¶m->postmaster_alive_fds, &postmaster_alive_fds, 6233 sizeof(postmaster_alive_fds)); 6234 #endif 6235 6236 memcpy(¶m->syslogPipe, &syslogPipe, sizeof(syslogPipe)); 6237 6238 strlcpy(param->my_exec_path, my_exec_path, MAXPGPATH); 6239 6240 strlcpy(param->pkglib_path, pkglib_path, MAXPGPATH); 6241 6242 strlcpy(param->ExtraOptions, ExtraOptions, MAXPGPATH); 6243 6244 return true; 6245 } 6246 6247 6248 #ifdef WIN32 6249 /* 6250 * Duplicate a handle for usage in a child process, and write the child 6251 * process instance of the handle to the parameter file. 6252 */ 6253 static bool 6254 write_duplicated_handle(HANDLE *dest, HANDLE src, HANDLE childProcess) 6255 { 6256 HANDLE hChild = INVALID_HANDLE_VALUE; 6257 6258 if (!DuplicateHandle(GetCurrentProcess(), 6259 src, 6260 childProcess, 6261 &hChild, 6262 0, 6263 TRUE, 6264 DUPLICATE_CLOSE_SOURCE | DUPLICATE_SAME_ACCESS)) 6265 { 6266 ereport(LOG, 6267 (errmsg_internal("could not duplicate handle to be written to backend parameter file: error code %lu", 6268 GetLastError()))); 6269 return false; 6270 } 6271 6272 *dest = hChild; 6273 return true; 6274 } 6275 6276 /* 6277 * Duplicate a socket for usage in a child process, and write the resulting 6278 * structure to the parameter file. 6279 * This is required because a number of LSPs (Layered Service Providers) very 6280 * common on Windows (antivirus, firewalls, download managers etc) break 6281 * straight socket inheritance. 6282 */ 6283 static bool 6284 write_inheritable_socket(InheritableSocket *dest, SOCKET src, pid_t childpid) 6285 { 6286 dest->origsocket = src; 6287 if (src != 0 && src != PGINVALID_SOCKET) 6288 { 6289 /* Actual socket */ 6290 if (WSADuplicateSocket(src, childpid, &dest->wsainfo) != 0) 6291 { 6292 ereport(LOG, 6293 (errmsg("could not duplicate socket %d for use in backend: error code %d", 6294 (int) src, WSAGetLastError()))); 6295 return false; 6296 } 6297 } 6298 return true; 6299 } 6300 6301 /* 6302 * Read a duplicate socket structure back, and get the socket descriptor. 6303 */ 6304 static void 6305 read_inheritable_socket(SOCKET *dest, InheritableSocket *src) 6306 { 6307 SOCKET s; 6308 6309 if (src->origsocket == PGINVALID_SOCKET || src->origsocket == 0) 6310 { 6311 /* Not a real socket! */ 6312 *dest = src->origsocket; 6313 } 6314 else 6315 { 6316 /* Actual socket, so create from structure */ 6317 s = WSASocket(FROM_PROTOCOL_INFO, 6318 FROM_PROTOCOL_INFO, 6319 FROM_PROTOCOL_INFO, 6320 &src->wsainfo, 6321 0, 6322 0); 6323 if (s == INVALID_SOCKET) 6324 { 6325 write_stderr("could not create inherited socket: error code %d\n", 6326 WSAGetLastError()); 6327 exit(1); 6328 } 6329 *dest = s; 6330 6331 /* 6332 * To make sure we don't get two references to the same socket, close 6333 * the original one. (This would happen when inheritance actually 6334 * works.. 6335 */ 6336 closesocket(src->origsocket); 6337 } 6338 } 6339 #endif 6340 6341 static void 6342 read_backend_variables(char *id, Port *port) 6343 { 6344 BackendParameters param; 6345 6346 #ifndef WIN32 6347 /* Non-win32 implementation reads from file */ 6348 FILE *fp; 6349 6350 /* Open file */ 6351 fp = AllocateFile(id, PG_BINARY_R); 6352 if (!fp) 6353 { 6354 write_stderr("could not open backend variables file \"%s\": %s\n", 6355 id, strerror(errno)); 6356 exit(1); 6357 } 6358 6359 if (fread(¶m, sizeof(param), 1, fp) != 1) 6360 { 6361 write_stderr("could not read from backend variables file \"%s\": %s\n", 6362 id, strerror(errno)); 6363 exit(1); 6364 } 6365 6366 /* Release file */ 6367 FreeFile(fp); 6368 if (unlink(id) != 0) 6369 { 6370 write_stderr("could not remove file \"%s\": %s\n", 6371 id, strerror(errno)); 6372 exit(1); 6373 } 6374 #else 6375 /* Win32 version uses mapped file */ 6376 HANDLE paramHandle; 6377 BackendParameters *paramp; 6378 6379 #ifdef _WIN64 6380 paramHandle = (HANDLE) _atoi64(id); 6381 #else 6382 paramHandle = (HANDLE) atol(id); 6383 #endif 6384 paramp = MapViewOfFile(paramHandle, FILE_MAP_READ, 0, 0, 0); 6385 if (!paramp) 6386 { 6387 write_stderr("could not map view of backend variables: error code %lu\n", 6388 GetLastError()); 6389 exit(1); 6390 } 6391 6392 memcpy(¶m, paramp, sizeof(BackendParameters)); 6393 6394 if (!UnmapViewOfFile(paramp)) 6395 { 6396 write_stderr("could not unmap view of backend variables: error code %lu\n", 6397 GetLastError()); 6398 exit(1); 6399 } 6400 6401 if (!CloseHandle(paramHandle)) 6402 { 6403 write_stderr("could not close handle to backend parameter variables: error code %lu\n", 6404 GetLastError()); 6405 exit(1); 6406 } 6407 #endif 6408 6409 restore_backend_variables(¶m, port); 6410 } 6411 6412 /* Restore critical backend variables from the BackendParameters struct */ 6413 static void 6414 restore_backend_variables(BackendParameters *param, Port *port) 6415 { 6416 memcpy(port, ¶m->port, sizeof(Port)); 6417 read_inheritable_socket(&port->sock, ¶m->portsocket); 6418 6419 SetDataDir(param->DataDir); 6420 6421 memcpy(&ListenSocket, ¶m->ListenSocket, sizeof(ListenSocket)); 6422 6423 MyCancelKey = param->MyCancelKey; 6424 MyPMChildSlot = param->MyPMChildSlot; 6425 6426 #ifdef WIN32 6427 ShmemProtectiveRegion = param->ShmemProtectiveRegion; 6428 #endif 6429 UsedShmemSegID = param->UsedShmemSegID; 6430 UsedShmemSegAddr = param->UsedShmemSegAddr; 6431 6432 ShmemLock = param->ShmemLock; 6433 ShmemVariableCache = param->ShmemVariableCache; 6434 ShmemBackendArray = param->ShmemBackendArray; 6435 6436 #ifndef HAVE_SPINLOCKS 6437 SpinlockSemaArray = param->SpinlockSemaArray; 6438 #endif 6439 NamedLWLockTrancheRequests = param->NamedLWLockTrancheRequests; 6440 NamedLWLockTrancheArray = param->NamedLWLockTrancheArray; 6441 MainLWLockArray = param->MainLWLockArray; 6442 ProcStructLock = param->ProcStructLock; 6443 ProcGlobal = param->ProcGlobal; 6444 AuxiliaryProcs = param->AuxiliaryProcs; 6445 PreparedXactProcs = param->PreparedXactProcs; 6446 PMSignalState = param->PMSignalState; 6447 read_inheritable_socket(&pgStatSock, ¶m->pgStatSock); 6448 6449 PostmasterPid = param->PostmasterPid; 6450 PgStartTime = param->PgStartTime; 6451 PgReloadTime = param->PgReloadTime; 6452 first_syslogger_file_time = param->first_syslogger_file_time; 6453 6454 redirection_done = param->redirection_done; 6455 IsBinaryUpgrade = param->IsBinaryUpgrade; 6456 max_safe_fds = param->max_safe_fds; 6457 6458 MaxBackends = param->MaxBackends; 6459 6460 #ifdef WIN32 6461 PostmasterHandle = param->PostmasterHandle; 6462 pgwin32_initial_signal_pipe = param->initial_signal_pipe; 6463 #else 6464 memcpy(&postmaster_alive_fds, ¶m->postmaster_alive_fds, 6465 sizeof(postmaster_alive_fds)); 6466 #endif 6467 6468 memcpy(&syslogPipe, ¶m->syslogPipe, sizeof(syslogPipe)); 6469 6470 strlcpy(my_exec_path, param->my_exec_path, MAXPGPATH); 6471 6472 strlcpy(pkglib_path, param->pkglib_path, MAXPGPATH); 6473 6474 strlcpy(ExtraOptions, param->ExtraOptions, MAXPGPATH); 6475 } 6476 6477 6478 Size 6479 ShmemBackendArraySize(void) 6480 { 6481 return mul_size(MaxLivePostmasterChildren(), sizeof(Backend)); 6482 } 6483 6484 void 6485 ShmemBackendArrayAllocation(void) 6486 { 6487 Size size = ShmemBackendArraySize(); 6488 6489 ShmemBackendArray = (Backend *) ShmemAlloc(size); 6490 /* Mark all slots as empty */ 6491 memset(ShmemBackendArray, 0, size); 6492 } 6493 6494 static void 6495 ShmemBackendArrayAdd(Backend *bn) 6496 { 6497 /* The array slot corresponding to my PMChildSlot should be free */ 6498 int i = bn->child_slot - 1; 6499 6500 Assert(ShmemBackendArray[i].pid == 0); 6501 ShmemBackendArray[i] = *bn; 6502 } 6503 6504 static void 6505 ShmemBackendArrayRemove(Backend *bn) 6506 { 6507 int i = bn->child_slot - 1; 6508 6509 Assert(ShmemBackendArray[i].pid == bn->pid); 6510 /* Mark the slot as empty */ 6511 ShmemBackendArray[i].pid = 0; 6512 } 6513 #endif /* EXEC_BACKEND */ 6514 6515 6516 #ifdef WIN32 6517 6518 /* 6519 * Subset implementation of waitpid() for Windows. We assume pid is -1 6520 * (that is, check all child processes) and options is WNOHANG (don't wait). 6521 */ 6522 static pid_t 6523 waitpid(pid_t pid, int *exitstatus, int options) 6524 { 6525 DWORD dwd; 6526 ULONG_PTR key; 6527 OVERLAPPED *ovl; 6528 6529 /* 6530 * Check if there are any dead children. If there are, return the pid of 6531 * the first one that died. 6532 */ 6533 if (GetQueuedCompletionStatus(win32ChildQueue, &dwd, &key, &ovl, 0)) 6534 { 6535 *exitstatus = (int) key; 6536 return dwd; 6537 } 6538 6539 return -1; 6540 } 6541 6542 /* 6543 * Note! Code below executes on a thread pool! All operations must 6544 * be thread safe! Note that elog() and friends must *not* be used. 6545 */ 6546 static void WINAPI 6547 pgwin32_deadchild_callback(PVOID lpParameter, BOOLEAN TimerOrWaitFired) 6548 { 6549 win32_deadchild_waitinfo *childinfo = (win32_deadchild_waitinfo *) lpParameter; 6550 DWORD exitcode; 6551 6552 if (TimerOrWaitFired) 6553 return; /* timeout. Should never happen, since we use 6554 * INFINITE as timeout value. */ 6555 6556 /* 6557 * Remove handle from wait - required even though it's set to wait only 6558 * once 6559 */ 6560 UnregisterWaitEx(childinfo->waitHandle, NULL); 6561 6562 if (!GetExitCodeProcess(childinfo->procHandle, &exitcode)) 6563 { 6564 /* 6565 * Should never happen. Inform user and set a fixed exitcode. 6566 */ 6567 write_stderr("could not read exit code for process\n"); 6568 exitcode = 255; 6569 } 6570 6571 if (!PostQueuedCompletionStatus(win32ChildQueue, childinfo->procId, (ULONG_PTR) exitcode, NULL)) 6572 write_stderr("could not post child completion status\n"); 6573 6574 /* 6575 * Handle is per-process, so we close it here instead of in the 6576 * originating thread 6577 */ 6578 CloseHandle(childinfo->procHandle); 6579 6580 /* 6581 * Free struct that was allocated before the call to 6582 * RegisterWaitForSingleObject() 6583 */ 6584 free(childinfo); 6585 6586 /* Queue SIGCHLD signal */ 6587 pg_queue_signal(SIGCHLD); 6588 } 6589 #endif /* WIN32 */ 6590 6591 /* 6592 * Initialize one and only handle for monitoring postmaster death. 6593 * 6594 * Called once in the postmaster, so that child processes can subsequently 6595 * monitor if their parent is dead. 6596 */ 6597 static void 6598 InitPostmasterDeathWatchHandle(void) 6599 { 6600 #ifndef WIN32 6601 6602 /* 6603 * Create a pipe. Postmaster holds the write end of the pipe open 6604 * (POSTMASTER_FD_OWN), and children hold the read end. Children can pass 6605 * the read file descriptor to select() to wake up in case postmaster 6606 * dies, or check for postmaster death with a (read() == 0). Children must 6607 * close the write end as soon as possible after forking, because EOF 6608 * won't be signaled in the read end until all processes have closed the 6609 * write fd. That is taken care of in ClosePostmasterPorts(). 6610 */ 6611 Assert(MyProcPid == PostmasterPid); 6612 if (pipe(postmaster_alive_fds) < 0) 6613 ereport(FATAL, 6614 (errcode_for_file_access(), 6615 errmsg_internal("could not create pipe to monitor postmaster death: %m"))); 6616 6617 /* 6618 * Set O_NONBLOCK to allow testing for the fd's presence with a read() 6619 * call. 6620 */ 6621 if (fcntl(postmaster_alive_fds[POSTMASTER_FD_WATCH], F_SETFL, O_NONBLOCK) == -1) 6622 ereport(FATAL, 6623 (errcode_for_socket_access(), 6624 errmsg_internal("could not set postmaster death monitoring pipe to nonblocking mode: %m"))); 6625 #else 6626 6627 /* 6628 * On Windows, we use a process handle for the same purpose. 6629 */ 6630 if (DuplicateHandle(GetCurrentProcess(), 6631 GetCurrentProcess(), 6632 GetCurrentProcess(), 6633 &PostmasterHandle, 6634 0, 6635 TRUE, 6636 DUPLICATE_SAME_ACCESS) == 0) 6637 ereport(FATAL, 6638 (errmsg_internal("could not duplicate postmaster handle: error code %lu", 6639 GetLastError()))); 6640 #endif /* WIN32 */ 6641 } 6642