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Diffstat (limited to '')
| -rw-r--r-- | src/backend/postmaster/postmaster.c | 6609 |
1 files changed, 6609 insertions, 0 deletions
diff --git a/src/backend/postmaster/postmaster.c b/src/backend/postmaster/postmaster.c new file mode 100644 index 0000000..918363c --- /dev/null +++ b/src/backend/postmaster/postmaster.c @@ -0,0 +1,6609 @@ +/*------------------------------------------------------------------------- + * + * postmaster.c + * This program acts as a clearing house for requests to the + * POSTGRES system. Frontend programs send a startup message + * to the Postmaster and the postmaster uses the info in the + * message to setup a backend process. + * + * The postmaster also manages system-wide operations such as + * startup and shutdown. The postmaster itself doesn't do those + * operations, mind you --- it just forks off a subprocess to do them + * at the right times. It also takes care of resetting the system + * if a backend crashes. + * + * The postmaster process creates the shared memory and semaphore + * pools during startup, but as a rule does not touch them itself. + * In particular, it is not a member of the PGPROC array of backends + * and so it cannot participate in lock-manager operations. Keeping + * the postmaster away from shared memory operations makes it simpler + * and more reliable. The postmaster is almost always able to recover + * from crashes of individual backends by resetting shared memory; + * if it did much with shared memory then it would be prone to crashing + * along with the backends. + * + * When a request message is received, we now fork() immediately. + * The child process performs authentication of the request, and + * then becomes a backend if successful. This allows the auth code + * to be written in a simple single-threaded style (as opposed to the + * crufty "poor man's multitasking" code that used to be needed). + * More importantly, it ensures that blockages in non-multithreaded + * libraries like SSL or PAM cannot cause denial of service to other + * clients. + * + * + * Portions Copyright (c) 1996-2022, PostgreSQL Global Development Group + * Portions Copyright (c) 1994, Regents of the University of California + * + * + * IDENTIFICATION + * src/backend/postmaster/postmaster.c + * + * NOTES + * + * Initialization: + * The Postmaster sets up shared memory data structures + * for the backends. + * + * Synchronization: + * The Postmaster shares memory with the backends but should avoid + * touching shared memory, so as not to become stuck if a crashing + * backend screws up locks or shared memory. Likewise, the Postmaster + * should never block on messages from frontend clients. + * + * Garbage Collection: + * The Postmaster cleans up after backends if they have an emergency + * exit and/or core dump. + * + * Error Reporting: + * Use write_stderr() only for reporting "interactive" errors + * (essentially, bogus arguments on the command line). Once the + * postmaster is launched, use ereport(). + * + *------------------------------------------------------------------------- + */ + +#include "postgres.h" + +#include <unistd.h> +#include <signal.h> +#include <time.h> +#include <sys/wait.h> +#include <ctype.h> +#include <sys/stat.h> +#include <sys/socket.h> +#include <fcntl.h> +#include <sys/param.h> +#include <netdb.h> +#include <limits.h> + +#ifdef HAVE_SYS_SELECT_H +#include <sys/select.h> +#endif + +#ifdef USE_BONJOUR +#include <dns_sd.h> +#endif + +#ifdef USE_SYSTEMD +#include <systemd/sd-daemon.h> +#endif + +#ifdef HAVE_PTHREAD_IS_THREADED_NP +#include <pthread.h> +#endif + +#include "access/transam.h" +#include "access/xlog.h" +#include "access/xlogrecovery.h" +#include "catalog/pg_control.h" +#include "common/file_perm.h" +#include "common/ip.h" +#include "common/pg_prng.h" +#include "common/string.h" +#include "lib/ilist.h" +#include "libpq/auth.h" +#include "libpq/libpq.h" +#include "libpq/pqformat.h" +#include "libpq/pqsignal.h" +#include "pg_getopt.h" +#include "pgstat.h" +#include "port/pg_bswap.h" +#include "postmaster/autovacuum.h" +#include "postmaster/auxprocess.h" +#include "postmaster/bgworker_internals.h" +#include "postmaster/fork_process.h" +#include "postmaster/interrupt.h" +#include "postmaster/pgarch.h" +#include "postmaster/postmaster.h" +#include "postmaster/syslogger.h" +#include "replication/logicallauncher.h" +#include "replication/walsender.h" +#include "storage/fd.h" +#include "storage/ipc.h" +#include "storage/pg_shmem.h" +#include "storage/pmsignal.h" +#include "storage/proc.h" +#include "tcop/tcopprot.h" +#include "utils/builtins.h" +#include "utils/datetime.h" +#include "utils/memutils.h" +#include "utils/pidfile.h" +#include "utils/ps_status.h" +#include "utils/queryjumble.h" +#include "utils/timeout.h" +#include "utils/timestamp.h" +#include "utils/varlena.h" + +#ifdef EXEC_BACKEND +#include "storage/spin.h" +#endif + + +/* + * Possible types of a backend. Beyond being the possible bkend_type values in + * struct bkend, these are OR-able request flag bits for SignalSomeChildren() + * and CountChildren(). + */ +#define BACKEND_TYPE_NORMAL 0x0001 /* normal backend */ +#define BACKEND_TYPE_AUTOVAC 0x0002 /* autovacuum worker process */ +#define BACKEND_TYPE_WALSND 0x0004 /* walsender process */ +#define BACKEND_TYPE_BGWORKER 0x0008 /* bgworker process */ +#define BACKEND_TYPE_ALL 0x000F /* OR of all the above */ + +/* + * List of active backends (or child processes anyway; we don't actually + * know whether a given child has become a backend or is still in the + * authorization phase). This is used mainly to keep track of how many + * children we have and send them appropriate signals when necessary. + * + * As shown in the above set of backend types, this list includes not only + * "normal" client sessions, but also autovacuum workers, walsenders, and + * background workers. (Note that at the time of launch, walsenders are + * labeled BACKEND_TYPE_NORMAL; we relabel them to BACKEND_TYPE_WALSND + * upon noticing they've changed their PMChildFlags entry. Hence that check + * must be done before any operation that needs to distinguish walsenders + * from normal backends.) + * + * Also, "dead_end" children are in it: these are children launched just for + * the purpose of sending a friendly rejection message to a would-be client. + * We must track them because they are attached to shared memory, but we know + * they will never become live backends. dead_end children are not assigned a + * PMChildSlot. dead_end children have bkend_type NORMAL. + * + * "Special" children such as the startup, bgwriter and autovacuum launcher + * tasks are not in this list. They are tracked via StartupPID and other + * pid_t variables below. (Thus, there can't be more than one of any given + * "special" child process type. We use BackendList entries for any child + * process there can be more than one of.) + */ +typedef struct bkend +{ + pid_t pid; /* process id of backend */ + int32 cancel_key; /* cancel key for cancels for this backend */ + int child_slot; /* PMChildSlot for this backend, if any */ + int bkend_type; /* child process flavor, see above */ + bool dead_end; /* is it going to send an error and quit? */ + bool bgworker_notify; /* gets bgworker start/stop notifications */ + dlist_node elem; /* list link in BackendList */ +} Backend; + +static dlist_head BackendList = DLIST_STATIC_INIT(BackendList); + +#ifdef EXEC_BACKEND +static Backend *ShmemBackendArray; +#endif + +BackgroundWorker *MyBgworkerEntry = NULL; + + + +/* The socket number we are listening for connections on */ +int PostPortNumber; + +/* The directory names for Unix socket(s) */ +char *Unix_socket_directories; + +/* The TCP listen address(es) */ +char *ListenAddresses; + +/* + * ReservedBackends is the number of backends reserved for superuser use. + * This number is taken out of the pool size given by MaxConnections so + * number of backend slots available to non-superusers is + * (MaxConnections - ReservedBackends). Note what this really means is + * "if there are <= ReservedBackends connections available, only superusers + * can make new connections" --- pre-existing superuser connections don't + * count against the limit. + */ +int ReservedBackends; + +/* The socket(s) we're listening to. */ +#define MAXLISTEN 64 +static pgsocket ListenSocket[MAXLISTEN]; + +/* + * These globals control the behavior of the postmaster in case some + * backend dumps core. Normally, it kills all peers of the dead backend + * and reinitializes shared memory. By specifying -s or -n, we can have + * the postmaster stop (rather than kill) peers and not reinitialize + * shared data structures. (Reinit is currently dead code, though.) + */ +static bool Reinit = true; +static int SendStop = false; + +/* still more option variables */ +bool EnableSSL = false; + +int PreAuthDelay = 0; +int AuthenticationTimeout = 60; + +bool log_hostname; /* for ps display and logging */ +bool Log_connections = false; +bool Db_user_namespace = false; + +bool enable_bonjour = false; +char *bonjour_name; +bool restart_after_crash = true; +bool remove_temp_files_after_crash = true; + +/* PIDs of special child processes; 0 when not running */ +static pid_t StartupPID = 0, + BgWriterPID = 0, + CheckpointerPID = 0, + WalWriterPID = 0, + WalReceiverPID = 0, + AutoVacPID = 0, + PgArchPID = 0, + SysLoggerPID = 0; + +/* Startup process's status */ +typedef enum +{ + STARTUP_NOT_RUNNING, + STARTUP_RUNNING, + STARTUP_SIGNALED, /* we sent it a SIGQUIT or SIGKILL */ + STARTUP_CRASHED +} StartupStatusEnum; + +static StartupStatusEnum StartupStatus = STARTUP_NOT_RUNNING; + +/* Startup/shutdown state */ +#define NoShutdown 0 +#define SmartShutdown 1 +#define FastShutdown 2 +#define ImmediateShutdown 3 + +static int Shutdown = NoShutdown; + +static bool FatalError = false; /* T if recovering from backend crash */ + +/* + * We use a simple state machine to control startup, shutdown, and + * crash recovery (which is rather like shutdown followed by startup). + * + * After doing all the postmaster initialization work, we enter PM_STARTUP + * state and the startup process is launched. The startup process begins by + * reading the control file and other preliminary initialization steps. + * In a normal startup, or after crash recovery, the startup process exits + * with exit code 0 and we switch to PM_RUN state. However, archive recovery + * is handled specially since it takes much longer and we would like to support + * hot standby during archive recovery. + * + * When the startup process is ready to start archive recovery, it signals the + * postmaster, and we switch to PM_RECOVERY state. The background writer and + * checkpointer are launched, while the startup process continues applying WAL. + * If Hot Standby is enabled, then, after reaching a consistent point in WAL + * redo, startup process signals us again, and we switch to PM_HOT_STANDBY + * state and begin accepting connections to perform read-only queries. When + * archive recovery is finished, the startup process exits with exit code 0 + * and we switch to PM_RUN state. + * + * Normal child backends can only be launched when we are in PM_RUN or + * PM_HOT_STANDBY state. (connsAllowed can also restrict launching.) + * In other states we handle connection requests by launching "dead_end" + * child processes, which will simply send the client an error message and + * quit. (We track these in the BackendList so that we can know when they + * are all gone; this is important because they're still connected to shared + * memory, and would interfere with an attempt to destroy the shmem segment, + * possibly leading to SHMALL failure when we try to make a new one.) + * In PM_WAIT_DEAD_END state we are waiting for all the dead_end children + * to drain out of the system, and therefore stop accepting connection + * requests at all until the last existing child has quit (which hopefully + * will not be very long). + * + * Notice that this state variable does not distinguish *why* we entered + * states later than PM_RUN --- Shutdown and FatalError must be consulted + * to find that out. FatalError is never true in PM_RECOVERY, PM_HOT_STANDBY, + * or PM_RUN states, nor in PM_SHUTDOWN states (because we don't enter those + * states when trying to recover from a crash). It can be true in PM_STARTUP + * state, because we don't clear it until we've successfully started WAL redo. + */ +typedef enum +{ + PM_INIT, /* postmaster starting */ + PM_STARTUP, /* waiting for startup subprocess */ + PM_RECOVERY, /* in archive recovery mode */ + PM_HOT_STANDBY, /* in hot standby mode */ + PM_RUN, /* normal "database is alive" state */ + PM_STOP_BACKENDS, /* need to stop remaining backends */ + PM_WAIT_BACKENDS, /* waiting for live backends to exit */ + PM_SHUTDOWN, /* waiting for checkpointer to do shutdown + * ckpt */ + PM_SHUTDOWN_2, /* waiting for archiver and walsenders to + * finish */ + PM_WAIT_DEAD_END, /* waiting for dead_end children to exit */ + PM_NO_CHILDREN /* all important children have exited */ +} PMState; + +static PMState pmState = PM_INIT; + +/* + * While performing a "smart shutdown", we restrict new connections but stay + * in PM_RUN or PM_HOT_STANDBY state until all the client backends are gone. + * connsAllowed is a sub-state indicator showing the active restriction. + * It is of no interest unless pmState is PM_RUN or PM_HOT_STANDBY. + */ +static bool connsAllowed = true; + +/* Start time of SIGKILL timeout during immediate shutdown or child crash */ +/* Zero means timeout is not running */ +static time_t AbortStartTime = 0; + +/* Length of said timeout */ +#define SIGKILL_CHILDREN_AFTER_SECS 5 + +static bool ReachedNormalRunning = false; /* T if we've reached PM_RUN */ + +bool ClientAuthInProgress = false; /* T during new-client + * authentication */ + +bool redirection_done = false; /* stderr redirected for syslogger? */ + +/* received START_AUTOVAC_LAUNCHER signal */ +static volatile sig_atomic_t start_autovac_launcher = false; + +/* the launcher needs to be signaled to communicate some condition */ +static volatile bool avlauncher_needs_signal = false; + +/* received START_WALRECEIVER signal */ +static volatile sig_atomic_t WalReceiverRequested = false; + +/* set when there's a worker that needs to be started up */ +static volatile bool StartWorkerNeeded = true; +static volatile bool HaveCrashedWorker = false; + +#ifdef USE_SSL +/* Set when and if SSL has been initialized properly */ +static bool LoadedSSL = false; +#endif + +#ifdef USE_BONJOUR +static DNSServiceRef bonjour_sdref = NULL; +#endif + +/* + * postmaster.c - function prototypes + */ +static void CloseServerPorts(int status, Datum arg); +static void unlink_external_pid_file(int status, Datum arg); +static void getInstallationPaths(const char *argv0); +static void checkControlFile(void); +static Port *ConnCreate(int serverFd); +static void ConnFree(Port *port); +static void reset_shared(void); +static void SIGHUP_handler(SIGNAL_ARGS); +static void pmdie(SIGNAL_ARGS); +static void reaper(SIGNAL_ARGS); +static void sigusr1_handler(SIGNAL_ARGS); +static void process_startup_packet_die(SIGNAL_ARGS); +static void dummy_handler(SIGNAL_ARGS); +static void StartupPacketTimeoutHandler(void); +static void CleanupBackend(int pid, int exitstatus); +static bool CleanupBackgroundWorker(int pid, int exitstatus); +static void HandleChildCrash(int pid, int exitstatus, const char *procname); +static void LogChildExit(int lev, const char *procname, + int pid, int exitstatus); +static void PostmasterStateMachine(void); +static void BackendInitialize(Port *port); +static void BackendRun(Port *port) pg_attribute_noreturn(); +static void ExitPostmaster(int status) pg_attribute_noreturn(); +static int ServerLoop(void); +static int BackendStartup(Port *port); +static int ProcessStartupPacket(Port *port, bool ssl_done, bool gss_done); +static void SendNegotiateProtocolVersion(List *unrecognized_protocol_options); +static void processCancelRequest(Port *port, void *pkt); +static int initMasks(fd_set *rmask); +static void report_fork_failure_to_client(Port *port, int errnum); +static CAC_state canAcceptConnections(int backend_type); +static bool RandomCancelKey(int32 *cancel_key); +static void signal_child(pid_t pid, int signal); +static bool SignalSomeChildren(int signal, int targets); +static void TerminateChildren(int signal); + +#define SignalChildren(sig) SignalSomeChildren(sig, BACKEND_TYPE_ALL) + +static int CountChildren(int target); +static bool assign_backendlist_entry(RegisteredBgWorker *rw); +static void maybe_start_bgworkers(void); +static bool CreateOptsFile(int argc, char *argv[], char *fullprogname); +static pid_t StartChildProcess(AuxProcType type); +static void StartAutovacuumWorker(void); +static void MaybeStartWalReceiver(void); +static void InitPostmasterDeathWatchHandle(void); + +/* + * Archiver is allowed to start up at the current postmaster state? + * + * If WAL archiving is enabled always, we are allowed to start archiver + * even during recovery. + */ +#define PgArchStartupAllowed() \ + (((XLogArchivingActive() && pmState == PM_RUN) || \ + (XLogArchivingAlways() && \ + (pmState == PM_RECOVERY || pmState == PM_HOT_STANDBY))) && \ + PgArchCanRestart()) + +#ifdef EXEC_BACKEND + +#ifdef WIN32 +#define WNOHANG 0 /* ignored, so any integer value will do */ + +static pid_t waitpid(pid_t pid, int *exitstatus, int options); +static void WINAPI pgwin32_deadchild_callback(PVOID lpParameter, BOOLEAN TimerOrWaitFired); + +static HANDLE win32ChildQueue; + +typedef struct +{ + HANDLE waitHandle; + HANDLE procHandle; + DWORD procId; +} win32_deadchild_waitinfo; +#endif /* WIN32 */ + +static pid_t backend_forkexec(Port *port); +static pid_t internal_forkexec(int argc, char *argv[], Port *port); + +/* Type for a socket that can be inherited to a client process */ +#ifdef WIN32 +typedef struct +{ + SOCKET origsocket; /* Original socket value, or PGINVALID_SOCKET + * if not a socket */ + WSAPROTOCOL_INFO wsainfo; +} InheritableSocket; +#else +typedef int InheritableSocket; +#endif + +/* + * Structure contains all variables passed to exec:ed backends + */ +typedef struct +{ + Port port; + InheritableSocket portsocket; + char DataDir[MAXPGPATH]; + pgsocket ListenSocket[MAXLISTEN]; + int32 MyCancelKey; + int MyPMChildSlot; +#ifndef WIN32 + unsigned long UsedShmemSegID; +#else + void *ShmemProtectiveRegion; + HANDLE UsedShmemSegID; +#endif + void *UsedShmemSegAddr; + slock_t *ShmemLock; + VariableCache ShmemVariableCache; + Backend *ShmemBackendArray; +#ifndef HAVE_SPINLOCKS + PGSemaphore *SpinlockSemaArray; +#endif + int NamedLWLockTrancheRequests; + NamedLWLockTranche *NamedLWLockTrancheArray; + LWLockPadded *MainLWLockArray; + slock_t *ProcStructLock; + PROC_HDR *ProcGlobal; + PGPROC *AuxiliaryProcs; + PGPROC *PreparedXactProcs; + PMSignalData *PMSignalState; + pid_t PostmasterPid; + TimestampTz PgStartTime; + TimestampTz PgReloadTime; + pg_time_t first_syslogger_file_time; + bool redirection_done; + bool IsBinaryUpgrade; + bool query_id_enabled; + int max_safe_fds; + int MaxBackends; +#ifdef WIN32 + HANDLE PostmasterHandle; + HANDLE initial_signal_pipe; + HANDLE syslogPipe[2]; +#else + int postmaster_alive_fds[2]; + int syslogPipe[2]; +#endif + char my_exec_path[MAXPGPATH]; + char pkglib_path[MAXPGPATH]; +} BackendParameters; + +static void read_backend_variables(char *id, Port *port); +static void restore_backend_variables(BackendParameters *param, Port *port); + +#ifndef WIN32 +static bool save_backend_variables(BackendParameters *param, Port *port); +#else +static bool save_backend_variables(BackendParameters *param, Port *port, + HANDLE childProcess, pid_t childPid); +#endif + +static void ShmemBackendArrayAdd(Backend *bn); +static void ShmemBackendArrayRemove(Backend *bn); +#endif /* EXEC_BACKEND */ + +#define StartupDataBase() StartChildProcess(StartupProcess) +#define StartArchiver() StartChildProcess(ArchiverProcess) +#define StartBackgroundWriter() StartChildProcess(BgWriterProcess) +#define StartCheckpointer() StartChildProcess(CheckpointerProcess) +#define StartWalWriter() StartChildProcess(WalWriterProcess) +#define StartWalReceiver() StartChildProcess(WalReceiverProcess) + +/* Macros to check exit status of a child process */ +#define EXIT_STATUS_0(st) ((st) == 0) +#define EXIT_STATUS_1(st) (WIFEXITED(st) && WEXITSTATUS(st) == 1) +#define EXIT_STATUS_3(st) (WIFEXITED(st) && WEXITSTATUS(st) == 3) + +#ifndef WIN32 +/* + * File descriptors for pipe used to monitor if postmaster is alive. + * First is POSTMASTER_FD_WATCH, second is POSTMASTER_FD_OWN. + */ +int postmaster_alive_fds[2] = {-1, -1}; +#else +/* Process handle of postmaster used for the same purpose on Windows */ +HANDLE PostmasterHandle; +#endif + +/* + * Postmaster main entry point + */ +void +PostmasterMain(int argc, char *argv[]) +{ + int opt; + int status; + char *userDoption = NULL; + bool listen_addr_saved = false; + int i; + char *output_config_variable = NULL; + + InitProcessGlobals(); + + PostmasterPid = MyProcPid; + + IsPostmasterEnvironment = true; + + /* + * Start our win32 signal implementation + */ +#ifdef WIN32 + pgwin32_signal_initialize(); +#endif + + /* + * We should not be creating any files or directories before we check the + * data directory (see checkDataDir()), but just in case set the umask to + * the most restrictive (owner-only) permissions. + * + * checkDataDir() will reset the umask based on the data directory + * permissions. + */ + umask(PG_MODE_MASK_OWNER); + + /* + * By default, palloc() requests in the postmaster will be allocated in + * the PostmasterContext, which is space that can be recycled by backends. + * Allocated data that needs to be available to backends should be + * allocated in TopMemoryContext. + */ + PostmasterContext = AllocSetContextCreate(TopMemoryContext, + "Postmaster", + ALLOCSET_DEFAULT_SIZES); + MemoryContextSwitchTo(PostmasterContext); + + /* Initialize paths to installation files */ + getInstallationPaths(argv[0]); + + /* + * Set up signal handlers for the postmaster process. + * + * In the postmaster, we use pqsignal_pm() rather than pqsignal() (which + * is used by all child processes and client processes). That has a + * couple of special behaviors: + * + * 1. Except on Windows, we tell sigaction() to block all signals for the + * duration of the signal handler. This is faster than our old approach + * of blocking/unblocking explicitly in the signal handler, and it should + * also prevent excessive stack consumption if signals arrive quickly. + * + * 2. We do not set the SA_RESTART flag. This is because signals will be + * blocked at all times except when ServerLoop is waiting for something to + * happen, and during that window, we want signals to exit the select(2) + * wait so that ServerLoop can respond if anything interesting happened. + * On some platforms, signals marked SA_RESTART would not cause the + * select() wait to end. + * + * Child processes will generally want SA_RESTART, so pqsignal() sets that + * flag. We expect children to set up their own handlers before + * unblocking signals. + * + * CAUTION: when changing this list, check for side-effects on the signal + * handling setup of child processes. See tcop/postgres.c, + * bootstrap/bootstrap.c, postmaster/bgwriter.c, postmaster/walwriter.c, + * postmaster/autovacuum.c, postmaster/pgarch.c, postmaster/syslogger.c, + * postmaster/bgworker.c and postmaster/checkpointer.c. + */ + pqinitmask(); + PG_SETMASK(&BlockSig); + + pqsignal_pm(SIGHUP, SIGHUP_handler); /* reread config file and have + * children do same */ + pqsignal_pm(SIGINT, pmdie); /* send SIGTERM and shut down */ + pqsignal_pm(SIGQUIT, pmdie); /* send SIGQUIT and die */ + pqsignal_pm(SIGTERM, pmdie); /* wait for children and shut down */ + pqsignal_pm(SIGALRM, SIG_IGN); /* ignored */ + pqsignal_pm(SIGPIPE, SIG_IGN); /* ignored */ + pqsignal_pm(SIGUSR1, sigusr1_handler); /* message from child process */ + pqsignal_pm(SIGUSR2, dummy_handler); /* unused, reserve for children */ + pqsignal_pm(SIGCHLD, reaper); /* handle child termination */ + +#ifdef SIGURG + + /* + * Ignore SIGURG for now. Child processes may change this (see + * InitializeLatchSupport), but they will not receive any such signals + * until they wait on a latch. + */ + pqsignal_pm(SIGURG, SIG_IGN); /* ignored */ +#endif + + /* + * No other place in Postgres should touch SIGTTIN/SIGTTOU handling. We + * ignore those signals in a postmaster environment, so that there is no + * risk of a child process freezing up due to writing to stderr. But for + * a standalone backend, their default handling is reasonable. Hence, all + * child processes should just allow the inherited settings to stand. + */ +#ifdef SIGTTIN + pqsignal_pm(SIGTTIN, SIG_IGN); /* ignored */ +#endif +#ifdef SIGTTOU + pqsignal_pm(SIGTTOU, SIG_IGN); /* ignored */ +#endif + + /* ignore SIGXFSZ, so that ulimit violations work like disk full */ +#ifdef SIGXFSZ + pqsignal_pm(SIGXFSZ, SIG_IGN); /* ignored */ +#endif + + /* + * Options setup + */ + InitializeGUCOptions(); + + opterr = 1; + + /* + * Parse command-line options. CAUTION: keep this in sync with + * tcop/postgres.c (the option sets should not conflict) and with the + * common help() function in main/main.c. + */ + while ((opt = getopt(argc, argv, "B:bc:C:D:d:EeFf:h:ijk:lN:nOPp:r:S:sTt:W:-:")) != -1) + { + switch (opt) + { + case 'B': + SetConfigOption("shared_buffers", optarg, PGC_POSTMASTER, PGC_S_ARGV); + break; + + case 'b': + /* Undocumented flag used for binary upgrades */ + IsBinaryUpgrade = true; + break; + + case 'C': + output_config_variable = strdup(optarg); + break; + + case 'D': + userDoption = strdup(optarg); + break; + + case 'd': + set_debug_options(atoi(optarg), PGC_POSTMASTER, PGC_S_ARGV); + break; + + case 'E': + SetConfigOption("log_statement", "all", PGC_POSTMASTER, PGC_S_ARGV); + break; + + case 'e': + SetConfigOption("datestyle", "euro", PGC_POSTMASTER, PGC_S_ARGV); + break; + + case 'F': + SetConfigOption("fsync", "false", PGC_POSTMASTER, PGC_S_ARGV); + break; + + case 'f': + if (!set_plan_disabling_options(optarg, PGC_POSTMASTER, PGC_S_ARGV)) + { + write_stderr("%s: invalid argument for option -f: \"%s\"\n", + progname, optarg); + ExitPostmaster(1); + } + break; + + case 'h': + SetConfigOption("listen_addresses", optarg, PGC_POSTMASTER, PGC_S_ARGV); + break; + + case 'i': + SetConfigOption("listen_addresses", "*", PGC_POSTMASTER, PGC_S_ARGV); + break; + + case 'j': + /* only used by interactive backend */ + break; + + case 'k': + SetConfigOption("unix_socket_directories", optarg, PGC_POSTMASTER, PGC_S_ARGV); + break; + + case 'l': + SetConfigOption("ssl", "true", PGC_POSTMASTER, PGC_S_ARGV); + break; + + case 'N': + SetConfigOption("max_connections", optarg, PGC_POSTMASTER, PGC_S_ARGV); + break; + + case 'n': + /* Don't reinit shared mem after abnormal exit */ + Reinit = false; + break; + + case 'O': + SetConfigOption("allow_system_table_mods", "true", PGC_POSTMASTER, PGC_S_ARGV); + break; + + case 'P': + SetConfigOption("ignore_system_indexes", "true", PGC_POSTMASTER, PGC_S_ARGV); + break; + + case 'p': + SetConfigOption("port", optarg, PGC_POSTMASTER, PGC_S_ARGV); + break; + + case 'r': + /* only used by single-user backend */ + break; + + case 'S': + SetConfigOption("work_mem", optarg, PGC_POSTMASTER, PGC_S_ARGV); + break; + + case 's': + SetConfigOption("log_statement_stats", "true", PGC_POSTMASTER, PGC_S_ARGV); + break; + + case 'T': + + /* + * In the event that some backend dumps core, send SIGSTOP, + * rather than SIGQUIT, to all its peers. This lets the wily + * post_hacker collect core dumps from everyone. + */ + SendStop = true; + break; + + case 't': + { + const char *tmp = get_stats_option_name(optarg); + + if (tmp) + { + SetConfigOption(tmp, "true", PGC_POSTMASTER, PGC_S_ARGV); + } + else + { + write_stderr("%s: invalid argument for option -t: \"%s\"\n", + progname, optarg); + ExitPostmaster(1); + } + break; + } + + case 'W': + SetConfigOption("post_auth_delay", optarg, PGC_POSTMASTER, PGC_S_ARGV); + break; + + case 'c': + case '-': + { + char *name, + *value; + + ParseLongOption(optarg, &name, &value); + if (!value) + { + if (opt == '-') + ereport(ERROR, + (errcode(ERRCODE_SYNTAX_ERROR), + errmsg("--%s requires a value", + optarg))); + else + ereport(ERROR, + (errcode(ERRCODE_SYNTAX_ERROR), + errmsg("-c %s requires a value", + optarg))); + } + + SetConfigOption(name, value, PGC_POSTMASTER, PGC_S_ARGV); + free(name); + if (value) + free(value); + break; + } + + default: + write_stderr("Try \"%s --help\" for more information.\n", + progname); + ExitPostmaster(1); + } + } + + /* + * Postmaster accepts no non-option switch arguments. + */ + if (optind < argc) + { + write_stderr("%s: invalid argument: \"%s\"\n", + progname, argv[optind]); + write_stderr("Try \"%s --help\" for more information.\n", + progname); + ExitPostmaster(1); + } + + /* + * Locate the proper configuration files and data directory, and read + * postgresql.conf for the first time. + */ + if (!SelectConfigFiles(userDoption, progname)) + ExitPostmaster(2); + + if (output_config_variable != NULL) + { + /* + * If this is a runtime-computed GUC, it hasn't yet been initialized, + * and the present value is not useful. However, this is a convenient + * place to print the value for most GUCs because it is safe to run + * postmaster startup to this point even if the server is already + * running. For the handful of runtime-computed GUCs that we cannot + * provide meaningful values for yet, we wait until later in + * postmaster startup to print the value. We won't be able to use -C + * on running servers for those GUCs, but using this option now would + * lead to incorrect results for them. + */ + int flags = GetConfigOptionFlags(output_config_variable, true); + + if ((flags & GUC_RUNTIME_COMPUTED) == 0) + { + /* + * "-C guc" was specified, so print GUC's value and exit. No + * extra permission check is needed because the user is reading + * inside the data dir. + */ + const char *config_val = GetConfigOption(output_config_variable, + false, false); + + puts(config_val ? config_val : ""); + ExitPostmaster(0); + } + + /* + * A runtime-computed GUC will be printed later on. As we initialize + * a server startup sequence, silence any log messages that may show + * up in the output generated. FATAL and more severe messages are + * useful to show, even if one would only expect at least PANIC. LOG + * entries are hidden. + */ + SetConfigOption("log_min_messages", "FATAL", PGC_SUSET, + PGC_S_OVERRIDE); + } + + /* Verify that DataDir looks reasonable */ + checkDataDir(); + + /* Check that pg_control exists */ + checkControlFile(); + + /* And switch working directory into it */ + ChangeToDataDir(); + + /* + * Check for invalid combinations of GUC settings. + */ + if (ReservedBackends >= MaxConnections) + { + write_stderr("%s: superuser_reserved_connections (%d) must be less than max_connections (%d)\n", + progname, + ReservedBackends, MaxConnections); + ExitPostmaster(1); + } + if (XLogArchiveMode > ARCHIVE_MODE_OFF && wal_level == WAL_LEVEL_MINIMAL) + ereport(ERROR, + (errmsg("WAL archival cannot be enabled when wal_level is \"minimal\""))); + if (max_wal_senders > 0 && wal_level == WAL_LEVEL_MINIMAL) + ereport(ERROR, + (errmsg("WAL streaming (max_wal_senders > 0) requires wal_level \"replica\" or \"logical\""))); + + /* + * Other one-time internal sanity checks can go here, if they are fast. + * (Put any slow processing further down, after postmaster.pid creation.) + */ + if (!CheckDateTokenTables()) + { + write_stderr("%s: invalid datetoken tables, please fix\n", progname); + ExitPostmaster(1); + } + + /* + * Now that we are done processing the postmaster arguments, reset + * getopt(3) library so that it will work correctly in subprocesses. + */ + optind = 1; +#ifdef HAVE_INT_OPTRESET + optreset = 1; /* some systems need this too */ +#endif + + /* For debugging: display postmaster environment */ + { + extern char **environ; + char **p; + + ereport(DEBUG3, + (errmsg_internal("%s: PostmasterMain: initial environment dump:", + progname))); + ereport(DEBUG3, + (errmsg_internal("-----------------------------------------"))); + for (p = environ; *p; ++p) + ereport(DEBUG3, + (errmsg_internal("\t%s", *p))); + ereport(DEBUG3, + (errmsg_internal("-----------------------------------------"))); + } + + /* + * Create lockfile for data directory. + * + * We want to do this before we try to grab the input sockets, because the + * data directory interlock is more reliable than the socket-file + * interlock (thanks to whoever decided to put socket files in /tmp :-(). + * For the same reason, it's best to grab the TCP socket(s) before the + * Unix socket(s). + * + * Also note that this internally sets up the on_proc_exit function that + * is responsible for removing both data directory and socket lockfiles; + * so it must happen before opening sockets so that at exit, the socket + * lockfiles go away after CloseServerPorts runs. + */ + CreateDataDirLockFile(true); + + /* + * Read the control file (for error checking and config info). + * + * Since we verify the control file's CRC, this has a useful side effect + * on machines where we need a run-time test for CRC support instructions. + * The postmaster will do the test once at startup, and then its child + * processes will inherit the correct function pointer and not need to + * repeat the test. + */ + LocalProcessControlFile(false); + + /* + * Register the apply launcher. It's probably a good idea to call this + * before any modules had a chance to take the background worker slots. + */ + ApplyLauncherRegister(); + + /* + * process any libraries that should be preloaded at postmaster start + */ + process_shared_preload_libraries(); + + /* + * Initialize SSL library, if specified. + */ +#ifdef USE_SSL + if (EnableSSL) + { + (void) secure_initialize(true); + LoadedSSL = true; + } +#endif + + /* + * Now that loadable modules have had their chance to alter any GUCs, + * calculate MaxBackends. + */ + InitializeMaxBackends(); + + /* + * Give preloaded libraries a chance to request additional shared memory. + */ + process_shmem_requests(); + + /* + * Now that loadable modules have had their chance to request additional + * shared memory, determine the value of any runtime-computed GUCs that + * depend on the amount of shared memory required. + */ + InitializeShmemGUCs(); + + /* + * Now that modules have been loaded, we can process any custom resource + * managers specified in the wal_consistency_checking GUC. + */ + InitializeWalConsistencyChecking(); + + /* + * If -C was specified with a runtime-computed GUC, we held off printing + * the value earlier, as the GUC was not yet initialized. We handle -C + * for most GUCs before we lock the data directory so that the option may + * be used on a running server. However, a handful of GUCs are runtime- + * computed and do not have meaningful values until after locking the data + * directory, and we cannot safely calculate their values earlier on a + * running server. At this point, such GUCs should be properly + * initialized, and we haven't yet set up shared memory, so this is a good + * time to handle the -C option for these special GUCs. + */ + if (output_config_variable != NULL) + { + const char *config_val = GetConfigOption(output_config_variable, + false, false); + + puts(config_val ? config_val : ""); + ExitPostmaster(0); + } + + /* + * Set up shared memory and semaphores. + */ + reset_shared(); + + /* + * Estimate number of openable files. This must happen after setting up + * semaphores, because on some platforms semaphores count as open files. + */ + set_max_safe_fds(); + + /* + * Set reference point for stack-depth checking. + */ + (void) set_stack_base(); + + /* + * Initialize pipe (or process handle on Windows) that allows children to + * wake up from sleep on postmaster death. + */ + InitPostmasterDeathWatchHandle(); + +#ifdef WIN32 + + /* + * Initialize I/O completion port used to deliver list of dead children. + */ + win32ChildQueue = CreateIoCompletionPort(INVALID_HANDLE_VALUE, NULL, 0, 1); + if (win32ChildQueue == NULL) + ereport(FATAL, + (errmsg("could not create I/O completion port for child queue"))); +#endif + +#ifdef EXEC_BACKEND + /* Write out nondefault GUC settings for child processes to use */ + write_nondefault_variables(PGC_POSTMASTER); + + /* + * Clean out the temp directory used to transmit parameters to child + * processes (see internal_forkexec, below). We must do this before + * launching any child processes, else we have a race condition: we could + * remove a parameter file before the child can read it. It should be + * safe to do so now, because we verified earlier that there are no + * conflicting Postgres processes in this data directory. + */ + RemovePgTempFilesInDir(PG_TEMP_FILES_DIR, true, false); +#endif + + /* + * Forcibly remove the files signaling a standby promotion request. + * Otherwise, the existence of those files triggers a promotion too early, + * whether a user wants that or not. + * + * This removal of files is usually unnecessary because they can exist + * only during a few moments during a standby promotion. However there is + * a race condition: if pg_ctl promote is executed and creates the files + * during a promotion, the files can stay around even after the server is + * brought up to be the primary. Then, if a new standby starts by using + * the backup taken from the new primary, the files can exist at server + * startup and must be removed in order to avoid an unexpected promotion. + * + * Note that promotion signal files need to be removed before the startup + * process is invoked. Because, after that, they can be used by + * postmaster's SIGUSR1 signal handler. + */ + RemovePromoteSignalFiles(); + + /* Do the same for logrotate signal file */ + RemoveLogrotateSignalFiles(); + + /* Remove any outdated file holding the current log filenames. */ + if (unlink(LOG_METAINFO_DATAFILE) < 0 && errno != ENOENT) + ereport(LOG, + (errcode_for_file_access(), + errmsg("could not remove file \"%s\": %m", + LOG_METAINFO_DATAFILE))); + + /* + * Initialize input sockets. + * + * Mark them all closed, and set up an on_proc_exit function that's + * charged with closing the sockets again at postmaster shutdown. + */ + for (i = 0; i < MAXLISTEN; i++) + ListenSocket[i] = PGINVALID_SOCKET; + + on_proc_exit(CloseServerPorts, 0); + + /* + * If enabled, start up syslogger collection subprocess + */ + SysLoggerPID = SysLogger_Start(); + + /* + * Reset whereToSendOutput from DestDebug (its starting state) to + * DestNone. This stops ereport from sending log messages to stderr unless + * Log_destination permits. We don't do this until the postmaster is + * fully launched, since startup failures may as well be reported to + * stderr. + * + * If we are in fact disabling logging to stderr, first emit a log message + * saying so, to provide a breadcrumb trail for users who may not remember + * that their logging is configured to go somewhere else. + */ + if (!(Log_destination & LOG_DESTINATION_STDERR)) + ereport(LOG, + (errmsg("ending log output to stderr"), + errhint("Future log output will go to log destination \"%s\".", + Log_destination_string))); + + whereToSendOutput = DestNone; + + /* + * Report server startup in log. While we could emit this much earlier, + * it seems best to do so after starting the log collector, if we intend + * to use one. + */ + ereport(LOG, + (errmsg("starting %s", PG_VERSION_STR))); + + /* + * Establish input sockets. + */ + if (ListenAddresses) + { + char *rawstring; + List *elemlist; + ListCell *l; + int success = 0; + + /* Need a modifiable copy of ListenAddresses */ + rawstring = pstrdup(ListenAddresses); + + /* Parse string into list of hostnames */ + if (!SplitGUCList(rawstring, ',', &elemlist)) + { + /* syntax error in list */ + ereport(FATAL, + (errcode(ERRCODE_INVALID_PARAMETER_VALUE), + errmsg("invalid list syntax in parameter \"%s\"", + "listen_addresses"))); + } + + foreach(l, elemlist) + { + char *curhost = (char *) lfirst(l); + + if (strcmp(curhost, "*") == 0) + status = StreamServerPort(AF_UNSPEC, NULL, + (unsigned short) PostPortNumber, + NULL, + ListenSocket, MAXLISTEN); + else + status = StreamServerPort(AF_UNSPEC, curhost, + (unsigned short) PostPortNumber, + NULL, + ListenSocket, MAXLISTEN); + + if (status == STATUS_OK) + { + success++; + /* record the first successful host addr in lockfile */ + if (!listen_addr_saved) + { + AddToDataDirLockFile(LOCK_FILE_LINE_LISTEN_ADDR, curhost); + listen_addr_saved = true; + } + } + else + ereport(WARNING, + (errmsg("could not create listen socket for \"%s\"", + curhost))); + } + + if (!success && elemlist != NIL) + ereport(FATAL, + (errmsg("could not create any TCP/IP sockets"))); + + list_free(elemlist); + pfree(rawstring); + } + +#ifdef USE_BONJOUR + /* Register for Bonjour only if we opened TCP socket(s) */ + if (enable_bonjour && ListenSocket[0] != PGINVALID_SOCKET) + { + DNSServiceErrorType err; + + /* + * We pass 0 for interface_index, which will result in registering on + * all "applicable" interfaces. It's not entirely clear from the + * DNS-SD docs whether this would be appropriate if we have bound to + * just a subset of the available network interfaces. + */ + err = DNSServiceRegister(&bonjour_sdref, + 0, + 0, + bonjour_name, + "_postgresql._tcp.", + NULL, + NULL, + pg_hton16(PostPortNumber), + 0, + NULL, + NULL, + NULL); + if (err != kDNSServiceErr_NoError) + ereport(LOG, + (errmsg("DNSServiceRegister() failed: error code %ld", + (long) err))); + + /* + * We don't bother to read the mDNS daemon's reply, and we expect that + * it will automatically terminate our registration when the socket is + * closed at postmaster termination. So there's nothing more to be + * done here. However, the bonjour_sdref is kept around so that + * forked children can close their copies of the socket. + */ + } +#endif + +#ifdef HAVE_UNIX_SOCKETS + if (Unix_socket_directories) + { + char *rawstring; + List *elemlist; + ListCell *l; + int success = 0; + + /* Need a modifiable copy of Unix_socket_directories */ + rawstring = pstrdup(Unix_socket_directories); + + /* Parse string into list of directories */ + if (!SplitDirectoriesString(rawstring, ',', &elemlist)) + { + /* syntax error in list */ + ereport(FATAL, + (errcode(ERRCODE_INVALID_PARAMETER_VALUE), + errmsg("invalid list syntax in parameter \"%s\"", + "unix_socket_directories"))); + } + + foreach(l, elemlist) + { + char *socketdir = (char *) lfirst(l); + + status = StreamServerPort(AF_UNIX, NULL, + (unsigned short) PostPortNumber, + socketdir, + ListenSocket, MAXLISTEN); + + if (status == STATUS_OK) + { + success++; + /* record the first successful Unix socket in lockfile */ + if (success == 1) + AddToDataDirLockFile(LOCK_FILE_LINE_SOCKET_DIR, socketdir); + } + else + ereport(WARNING, + (errmsg("could not create Unix-domain socket in directory \"%s\"", + socketdir))); + } + + if (!success && elemlist != NIL) + ereport(FATAL, + (errmsg("could not create any Unix-domain sockets"))); + + list_free_deep(elemlist); + pfree(rawstring); + } +#endif + + /* + * check that we have some socket to listen on + */ + if (ListenSocket[0] == PGINVALID_SOCKET) + ereport(FATAL, + (errmsg("no socket created for listening"))); + + /* + * If no valid TCP ports, write an empty line for listen address, + * indicating the Unix socket must be used. Note that this line is not + * added to the lock file until there is a socket backing it. + */ + if (!listen_addr_saved) + AddToDataDirLockFile(LOCK_FILE_LINE_LISTEN_ADDR, ""); + + /* + * Record postmaster options. We delay this till now to avoid recording + * bogus options (eg, unusable port number). + */ + if (!CreateOptsFile(argc, argv, my_exec_path)) + ExitPostmaster(1); + + /* + * Write the external PID file if requested + */ + if (external_pid_file) + { + FILE *fpidfile = fopen(external_pid_file, "w"); + + if (fpidfile) + { + fprintf(fpidfile, "%d\n", MyProcPid); + fclose(fpidfile); + + /* Make PID file world readable */ + if (chmod(external_pid_file, S_IRUSR | S_IWUSR | S_IRGRP | S_IROTH) != 0) + write_stderr("%s: could not change permissions of external PID file \"%s\": %s\n", + progname, external_pid_file, strerror(errno)); + } + else + write_stderr("%s: could not write external PID file \"%s\": %s\n", + progname, external_pid_file, strerror(errno)); + + on_proc_exit(unlink_external_pid_file, 0); + } + + /* + * Remove old temporary files. At this point there can be no other + * Postgres processes running in this directory, so this should be safe. + */ + RemovePgTempFiles(); + + /* + * Initialize the autovacuum subsystem (again, no process start yet) + */ + autovac_init(); + + /* + * Load configuration files for client authentication. + */ + if (!load_hba()) + { + /* + * It makes no sense to continue if we fail to load the HBA file, + * since there is no way to connect to the database in this case. + */ + ereport(FATAL, + (errmsg("could not load pg_hba.conf"))); + } + if (!load_ident()) + { + /* + * We can start up without the IDENT file, although it means that you + * cannot log in using any of the authentication methods that need a + * user name mapping. load_ident() already logged the details of error + * to the log. + */ + } + +#ifdef HAVE_PTHREAD_IS_THREADED_NP + + /* + * On macOS, libintl replaces setlocale() with a version that calls + * CFLocaleCopyCurrent() when its second argument is "" and every relevant + * environment variable is unset or empty. CFLocaleCopyCurrent() makes + * the process multithreaded. The postmaster calls sigprocmask() and + * calls fork() without an immediate exec(), both of which have undefined + * behavior in a multithreaded program. A multithreaded postmaster is the + * normal case on Windows, which offers neither fork() nor sigprocmask(). + */ + if (pthread_is_threaded_np() != 0) + ereport(FATAL, + (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE), + errmsg("postmaster became multithreaded during startup"), + errhint("Set the LC_ALL environment variable to a valid locale."))); +#endif + + /* + * Remember postmaster startup time + */ + PgStartTime = GetCurrentTimestamp(); + + /* + * Report postmaster status in the postmaster.pid file, to allow pg_ctl to + * see what's happening. + */ + AddToDataDirLockFile(LOCK_FILE_LINE_PM_STATUS, PM_STATUS_STARTING); + + /* Start bgwriter and checkpointer so they can help with recovery */ + if (CheckpointerPID == 0) + CheckpointerPID = StartCheckpointer(); + if (BgWriterPID == 0) + BgWriterPID = StartBackgroundWriter(); + + /* + * We're ready to rock and roll... + */ + StartupPID = StartupDataBase(); + Assert(StartupPID != 0); + StartupStatus = STARTUP_RUNNING; + pmState = PM_STARTUP; + + /* Some workers may be scheduled to start now */ + maybe_start_bgworkers(); + + status = ServerLoop(); + + /* + * ServerLoop probably shouldn't ever return, but if it does, close down. + */ + ExitPostmaster(status != STATUS_OK); + + abort(); /* not reached */ +} + + +/* + * on_proc_exit callback to close server's listen sockets + */ +static void +CloseServerPorts(int status, Datum arg) +{ + int i; + + /* + * First, explicitly close all the socket FDs. We used to just let this + * happen implicitly at postmaster exit, but it's better to close them + * before we remove the postmaster.pid lockfile; otherwise there's a race + * condition if a new postmaster wants to re-use the TCP port number. + */ + for (i = 0; i < MAXLISTEN; i++) + { + if (ListenSocket[i] != PGINVALID_SOCKET) + { + StreamClose(ListenSocket[i]); + ListenSocket[i] = PGINVALID_SOCKET; + } + } + + /* + * Next, remove any filesystem entries for Unix sockets. To avoid race + * conditions against incoming postmasters, this must happen after closing + * the sockets and before removing lock files. + */ + RemoveSocketFiles(); + + /* + * We don't do anything about socket lock files here; those will be + * removed in a later on_proc_exit callback. + */ +} + +/* + * on_proc_exit callback to delete external_pid_file + */ +static void +unlink_external_pid_file(int status, Datum arg) +{ + if (external_pid_file) + unlink(external_pid_file); +} + + +/* + * Compute and check the directory paths to files that are part of the + * installation (as deduced from the postgres executable's own location) + */ +static void +getInstallationPaths(const char *argv0) +{ + DIR *pdir; + + /* Locate the postgres executable itself */ + if (find_my_exec(argv0, my_exec_path) < 0) + ereport(FATAL, + (errmsg("%s: could not locate my own executable path", argv0))); + +#ifdef EXEC_BACKEND + /* Locate executable backend before we change working directory */ + if (find_other_exec(argv0, "postgres", PG_BACKEND_VERSIONSTR, + postgres_exec_path) < 0) + ereport(FATAL, + (errmsg("%s: could not locate matching postgres executable", + argv0))); +#endif + + /* + * Locate the pkglib directory --- this has to be set early in case we try + * to load any modules from it in response to postgresql.conf entries. + */ + get_pkglib_path(my_exec_path, pkglib_path); + + /* + * Verify that there's a readable directory there; otherwise the Postgres + * installation is incomplete or corrupt. (A typical cause of this + * failure is that the postgres executable has been moved or hardlinked to + * some directory that's not a sibling of the installation lib/ + * directory.) + */ + pdir = AllocateDir(pkglib_path); + if (pdir == NULL) + ereport(ERROR, + (errcode_for_file_access(), + errmsg("could not open directory \"%s\": %m", + pkglib_path), + errhint("This may indicate an incomplete PostgreSQL installation, or that the file \"%s\" has been moved away from its proper location.", + my_exec_path))); + FreeDir(pdir); + + /* + * XXX is it worth similarly checking the share/ directory? If the lib/ + * directory is there, then share/ probably is too. + */ +} + +/* + * Check that pg_control exists in the correct location in the data directory. + * + * No attempt is made to validate the contents of pg_control here. This is + * just a sanity check to see if we are looking at a real data directory. + */ +static void +checkControlFile(void) +{ + char path[MAXPGPATH]; + FILE *fp; + + snprintf(path, sizeof(path), "%s/global/pg_control", DataDir); + + fp = AllocateFile(path, PG_BINARY_R); + if (fp == NULL) + { + write_stderr("%s: could not find the database system\n" + "Expected to find it in the directory \"%s\",\n" + "but could not open file \"%s\": %s\n", + progname, DataDir, path, strerror(errno)); + ExitPostmaster(2); + } + FreeFile(fp); +} + +/* + * Determine how long should we let ServerLoop sleep. + * + * In normal conditions we wait at most one minute, to ensure that the other + * background tasks handled by ServerLoop get done even when no requests are + * arriving. However, if there are background workers waiting to be started, + * we don't actually sleep so that they are quickly serviced. Other exception + * cases are as shown in the code. + */ +static void +DetermineSleepTime(struct timeval *timeout) +{ + TimestampTz next_wakeup = 0; + + /* + * Normal case: either there are no background workers at all, or we're in + * a shutdown sequence (during which we ignore bgworkers altogether). + */ + if (Shutdown > NoShutdown || + (!StartWorkerNeeded && !HaveCrashedWorker)) + { + if (AbortStartTime != 0) + { + /* time left to abort; clamp to 0 in case it already expired */ + timeout->tv_sec = SIGKILL_CHILDREN_AFTER_SECS - + (time(NULL) - AbortStartTime); + timeout->tv_sec = Max(timeout->tv_sec, 0); + timeout->tv_usec = 0; + } + else + { + timeout->tv_sec = 60; + timeout->tv_usec = 0; + } + return; + } + + if (StartWorkerNeeded) + { + timeout->tv_sec = 0; + timeout->tv_usec = 0; + return; + } + + if (HaveCrashedWorker) + { + slist_mutable_iter siter; + + /* + * When there are crashed bgworkers, we sleep just long enough that + * they are restarted when they request to be. Scan the list to + * determine the minimum of all wakeup times according to most recent + * crash time and requested restart interval. + */ + slist_foreach_modify(siter, &BackgroundWorkerList) + { + RegisteredBgWorker *rw; + TimestampTz this_wakeup; + + rw = slist_container(RegisteredBgWorker, rw_lnode, siter.cur); + + if (rw->rw_crashed_at == 0) + continue; + + if (rw->rw_worker.bgw_restart_time == BGW_NEVER_RESTART + || rw->rw_terminate) + { + ForgetBackgroundWorker(&siter); + continue; + } + + this_wakeup = TimestampTzPlusMilliseconds(rw->rw_crashed_at, + 1000L * rw->rw_worker.bgw_restart_time); + if (next_wakeup == 0 || this_wakeup < next_wakeup) + next_wakeup = this_wakeup; + } + } + + if (next_wakeup != 0) + { + long secs; + int microsecs; + + TimestampDifference(GetCurrentTimestamp(), next_wakeup, + &secs, µsecs); + timeout->tv_sec = secs; + timeout->tv_usec = microsecs; + + /* Ensure we don't exceed one minute */ + if (timeout->tv_sec > 60) + { + timeout->tv_sec = 60; + timeout->tv_usec = 0; + } + } + else + { + timeout->tv_sec = 60; + timeout->tv_usec = 0; + } +} + +/* + * Main idle loop of postmaster + * + * NB: Needs to be called with signals blocked + */ +static int +ServerLoop(void) +{ + fd_set readmask; + int nSockets; + time_t last_lockfile_recheck_time, + last_touch_time; + + last_lockfile_recheck_time = last_touch_time = time(NULL); + + nSockets = initMasks(&readmask); + + for (;;) + { + fd_set rmask; + int selres; + time_t now; + + /* + * Wait for a connection request to arrive. + * + * We block all signals except while sleeping. That makes it safe for + * signal handlers, which again block all signals while executing, to + * do nontrivial work. + * + * If we are in PM_WAIT_DEAD_END state, then we don't want to accept + * any new connections, so we don't call select(), and just sleep. + */ + memcpy((char *) &rmask, (char *) &readmask, sizeof(fd_set)); + + if (pmState == PM_WAIT_DEAD_END) + { + PG_SETMASK(&UnBlockSig); + + pg_usleep(100000L); /* 100 msec seems reasonable */ + selres = 0; + + PG_SETMASK(&BlockSig); + } + else + { + /* must set timeout each time; some OSes change it! */ + struct timeval timeout; + + /* Needs to run with blocked signals! */ + DetermineSleepTime(&timeout); + + PG_SETMASK(&UnBlockSig); + + selres = select(nSockets, &rmask, NULL, NULL, &timeout); + + PG_SETMASK(&BlockSig); + } + + /* Now check the select() result */ + if (selres < 0) + { + if (errno != EINTR && errno != EWOULDBLOCK) + { + ereport(LOG, + (errcode_for_socket_access(), + errmsg("select() failed in postmaster: %m"))); + return STATUS_ERROR; + } + } + + /* + * New connection pending on any of our sockets? If so, fork a child + * process to deal with it. + */ + if (selres > 0) + { + int i; + + for (i = 0; i < MAXLISTEN; i++) + { + if (ListenSocket[i] == PGINVALID_SOCKET) + break; + if (FD_ISSET(ListenSocket[i], &rmask)) + { + Port *port; + + port = ConnCreate(ListenSocket[i]); + if (port) + { + BackendStartup(port); + + /* + * We no longer need the open socket or port structure + * in this process + */ + StreamClose(port->sock); + ConnFree(port); + } + } + } + } + + /* If we have lost the log collector, try to start a new one */ + if (SysLoggerPID == 0 && Logging_collector) + SysLoggerPID = SysLogger_Start(); + + /* + * If no background writer process is running, and we are not in a + * state that prevents it, start one. It doesn't matter if this + * fails, we'll just try again later. Likewise for the checkpointer. + */ + if (pmState == PM_RUN || pmState == PM_RECOVERY || + pmState == PM_HOT_STANDBY || pmState == PM_STARTUP) + { + if (CheckpointerPID == 0) + CheckpointerPID = StartCheckpointer(); + if (BgWriterPID == 0) + BgWriterPID = StartBackgroundWriter(); + } + + /* + * Likewise, if we have lost the walwriter process, try to start a new + * one. But this is needed only in normal operation (else we cannot + * be writing any new WAL). + */ + if (WalWriterPID == 0 && pmState == PM_RUN) + WalWriterPID = StartWalWriter(); + + /* + * If we have lost the autovacuum launcher, try to start a new one. We + * don't want autovacuum to run in binary upgrade mode because + * autovacuum might update relfrozenxid for empty tables before the + * physical files are put in place. + */ + if (!IsBinaryUpgrade && AutoVacPID == 0 && + (AutoVacuumingActive() || start_autovac_launcher) && + pmState == PM_RUN) + { + AutoVacPID = StartAutoVacLauncher(); + if (AutoVacPID != 0) + start_autovac_launcher = false; /* signal processed */ + } + + /* If we have lost the archiver, try to start a new one. */ + if (PgArchPID == 0 && PgArchStartupAllowed()) + PgArchPID = StartArchiver(); + + /* If we need to signal the autovacuum launcher, do so now */ + if (avlauncher_needs_signal) + { + avlauncher_needs_signal = false; + if (AutoVacPID != 0) + kill(AutoVacPID, SIGUSR2); + } + + /* If we need to start a WAL receiver, try to do that now */ + if (WalReceiverRequested) + MaybeStartWalReceiver(); + + /* Get other worker processes running, if needed */ + if (StartWorkerNeeded || HaveCrashedWorker) + maybe_start_bgworkers(); + +#ifdef HAVE_PTHREAD_IS_THREADED_NP + + /* + * With assertions enabled, check regularly for appearance of + * additional threads. All builds check at start and exit. + */ + Assert(pthread_is_threaded_np() == 0); +#endif + + /* + * Lastly, check to see if it's time to do some things that we don't + * want to do every single time through the loop, because they're a + * bit expensive. Note that there's up to a minute of slop in when + * these tasks will be performed, since DetermineSleepTime() will let + * us sleep at most that long; except for SIGKILL timeout which has + * special-case logic there. + */ + now = time(NULL); + + /* + * If we already sent SIGQUIT to children and they are slow to shut + * down, it's time to send them SIGKILL. This doesn't happen + * normally, but under certain conditions backends can get stuck while + * shutting down. This is a last measure to get them unwedged. + * + * Note we also do this during recovery from a process crash. + */ + if ((Shutdown >= ImmediateShutdown || (FatalError && !SendStop)) && + AbortStartTime != 0 && + (now - AbortStartTime) >= SIGKILL_CHILDREN_AFTER_SECS) + { + /* We were gentle with them before. Not anymore */ + ereport(LOG, + (errmsg("issuing SIGKILL to recalcitrant children"))); + TerminateChildren(SIGKILL); + /* reset flag so we don't SIGKILL again */ + AbortStartTime = 0; + } + + /* + * Once a minute, verify that postmaster.pid hasn't been removed or + * overwritten. If it has, we force a shutdown. This avoids having + * postmasters and child processes hanging around after their database + * is gone, and maybe causing problems if a new database cluster is + * created in the same place. It also provides some protection + * against a DBA foolishly removing postmaster.pid and manually + * starting a new postmaster. Data corruption is likely to ensue from + * that anyway, but we can minimize the damage by aborting ASAP. + */ + if (now - last_lockfile_recheck_time >= 1 * SECS_PER_MINUTE) + { + if (!RecheckDataDirLockFile()) + { + ereport(LOG, + (errmsg("performing immediate shutdown because data directory lock file is invalid"))); + kill(MyProcPid, SIGQUIT); + } + last_lockfile_recheck_time = now; + } + + /* + * Touch Unix socket and lock files every 58 minutes, to ensure that + * they are not removed by overzealous /tmp-cleaning tasks. We assume + * no one runs cleaners with cutoff times of less than an hour ... + */ + if (now - last_touch_time >= 58 * SECS_PER_MINUTE) + { + TouchSocketFiles(); + TouchSocketLockFiles(); + last_touch_time = now; + } + } +} + +/* + * Initialise the masks for select() for the ports we are listening on. + * Return the number of sockets to listen on. + */ +static int +initMasks(fd_set *rmask) +{ + int maxsock = -1; + int i; + + FD_ZERO(rmask); + + for (i = 0; i < MAXLISTEN; i++) + { + int fd = ListenSocket[i]; + + if (fd == PGINVALID_SOCKET) + break; + FD_SET(fd, rmask); + + if (fd > maxsock) + maxsock = fd; + } + + return maxsock + 1; +} + + +/* + * Read a client's startup packet and do something according to it. + * + * Returns STATUS_OK or STATUS_ERROR, or might call ereport(FATAL) and + * not return at all. + * + * (Note that ereport(FATAL) stuff is sent to the client, so only use it + * if that's what you want. Return STATUS_ERROR if you don't want to + * send anything to the client, which would typically be appropriate + * if we detect a communications failure.) + * + * Set ssl_done and/or gss_done when negotiation of an encrypted layer + * (currently, TLS or GSSAPI) is completed. A successful negotiation of either + * encryption layer sets both flags, but a rejected negotiation sets only the + * flag for that layer, since the client may wish to try the other one. We + * should make no assumption here about the order in which the client may make + * requests. + */ +static int +ProcessStartupPacket(Port *port, bool ssl_done, bool gss_done) +{ + int32 len; + char *buf; + ProtocolVersion proto; + MemoryContext oldcontext; + + pq_startmsgread(); + + /* + * Grab the first byte of the length word separately, so that we can tell + * whether we have no data at all or an incomplete packet. (This might + * sound inefficient, but it's not really, because of buffering in + * pqcomm.c.) + */ + if (pq_getbytes((char *) &len, 1) == EOF) + { + /* + * If we get no data at all, don't clutter the log with a complaint; + * such cases often occur for legitimate reasons. An example is that + * we might be here after responding to NEGOTIATE_SSL_CODE, and if the + * client didn't like our response, it'll probably just drop the + * connection. Service-monitoring software also often just opens and + * closes a connection without sending anything. (So do port + * scanners, which may be less benign, but it's not really our job to + * notice those.) + */ + return STATUS_ERROR; + } + + if (pq_getbytes(((char *) &len) + 1, 3) == EOF) + { + /* Got a partial length word, so bleat about that */ + if (!ssl_done && !gss_done) + ereport(COMMERROR, + (errcode(ERRCODE_PROTOCOL_VIOLATION), + errmsg("incomplete startup packet"))); + return STATUS_ERROR; + } + + len = pg_ntoh32(len); + len -= 4; + + if (len < (int32) sizeof(ProtocolVersion) || + len > MAX_STARTUP_PACKET_LENGTH) + { + ereport(COMMERROR, + (errcode(ERRCODE_PROTOCOL_VIOLATION), + errmsg("invalid length of startup packet"))); + return STATUS_ERROR; + } + + /* + * Allocate space to hold the startup packet, plus one extra byte that's + * initialized to be zero. This ensures we will have null termination of + * all strings inside the packet. + */ + buf = palloc(len + 1); + buf[len] = '\0'; + + if (pq_getbytes(buf, len) == EOF) + { + ereport(COMMERROR, + (errcode(ERRCODE_PROTOCOL_VIOLATION), + errmsg("incomplete startup packet"))); + return STATUS_ERROR; + } + pq_endmsgread(); + + /* + * The first field is either a protocol version number or a special + * request code. + */ + port->proto = proto = pg_ntoh32(*((ProtocolVersion *) buf)); + + if (proto == CANCEL_REQUEST_CODE) + { + if (len != sizeof(CancelRequestPacket)) + { + ereport(COMMERROR, + (errcode(ERRCODE_PROTOCOL_VIOLATION), + errmsg("invalid length of startup packet"))); + return STATUS_ERROR; + } + processCancelRequest(port, buf); + /* Not really an error, but we don't want to proceed further */ + return STATUS_ERROR; + } + + if (proto == NEGOTIATE_SSL_CODE && !ssl_done) + { + char SSLok; + +#ifdef USE_SSL + /* No SSL when disabled or on Unix sockets */ + if (!LoadedSSL || port->laddr.addr.ss_family == AF_UNIX) + SSLok = 'N'; + else + SSLok = 'S'; /* Support for SSL */ +#else + SSLok = 'N'; /* No support for SSL */ +#endif + +retry1: + if (send(port->sock, &SSLok, 1, 0) != 1) + { + if (errno == EINTR) + goto retry1; /* if interrupted, just retry */ + ereport(COMMERROR, + (errcode_for_socket_access(), + errmsg("failed to send SSL negotiation response: %m"))); + return STATUS_ERROR; /* close the connection */ + } + +#ifdef USE_SSL + if (SSLok == 'S' && secure_open_server(port) == -1) + return STATUS_ERROR; +#endif + + /* + * At this point we should have no data already buffered. If we do, + * it was received before we performed the SSL handshake, so it wasn't + * encrypted and indeed may have been injected by a man-in-the-middle. + * We report this case to the client. + */ + if (pq_buffer_has_data()) + ereport(FATAL, + (errcode(ERRCODE_PROTOCOL_VIOLATION), + errmsg("received unencrypted data after SSL request"), + errdetail("This could be either a client-software bug or evidence of an attempted man-in-the-middle attack."))); + + /* + * regular startup packet, cancel, etc packet should follow, but not + * another SSL negotiation request, and a GSS request should only + * follow if SSL was rejected (client may negotiate in either order) + */ + return ProcessStartupPacket(port, true, SSLok == 'S'); + } + else if (proto == NEGOTIATE_GSS_CODE && !gss_done) + { + char GSSok = 'N'; + +#ifdef ENABLE_GSS + /* No GSSAPI encryption when on Unix socket */ + if (port->laddr.addr.ss_family != AF_UNIX) + GSSok = 'G'; +#endif + + while (send(port->sock, &GSSok, 1, 0) != 1) + { + if (errno == EINTR) + continue; + ereport(COMMERROR, + (errcode_for_socket_access(), + errmsg("failed to send GSSAPI negotiation response: %m"))); + return STATUS_ERROR; /* close the connection */ + } + +#ifdef ENABLE_GSS + if (GSSok == 'G' && secure_open_gssapi(port) == -1) + return STATUS_ERROR; +#endif + + /* + * At this point we should have no data already buffered. If we do, + * it was received before we performed the GSS handshake, so it wasn't + * encrypted and indeed may have been injected by a man-in-the-middle. + * We report this case to the client. + */ + if (pq_buffer_has_data()) + ereport(FATAL, + (errcode(ERRCODE_PROTOCOL_VIOLATION), + errmsg("received unencrypted data after GSSAPI encryption request"), + errdetail("This could be either a client-software bug or evidence of an attempted man-in-the-middle attack."))); + + /* + * regular startup packet, cancel, etc packet should follow, but not + * another GSS negotiation request, and an SSL request should only + * follow if GSS was rejected (client may negotiate in either order) + */ + return ProcessStartupPacket(port, GSSok == 'G', true); + } + + /* Could add additional special packet types here */ + + /* + * Set FrontendProtocol now so that ereport() knows what format to send if + * we fail during startup. + */ + FrontendProtocol = proto; + + /* Check that the major protocol version is in range. */ + if (PG_PROTOCOL_MAJOR(proto) < PG_PROTOCOL_MAJOR(PG_PROTOCOL_EARLIEST) || + PG_PROTOCOL_MAJOR(proto) > PG_PROTOCOL_MAJOR(PG_PROTOCOL_LATEST)) + ereport(FATAL, + (errcode(ERRCODE_FEATURE_NOT_SUPPORTED), + errmsg("unsupported frontend protocol %u.%u: server supports %u.0 to %u.%u", + PG_PROTOCOL_MAJOR(proto), PG_PROTOCOL_MINOR(proto), + PG_PROTOCOL_MAJOR(PG_PROTOCOL_EARLIEST), + PG_PROTOCOL_MAJOR(PG_PROTOCOL_LATEST), + PG_PROTOCOL_MINOR(PG_PROTOCOL_LATEST)))); + + /* + * Now fetch parameters out of startup packet and save them into the Port + * structure. All data structures attached to the Port struct must be + * allocated in TopMemoryContext so that they will remain available in a + * running backend (even after PostmasterContext is destroyed). We need + * not worry about leaking this storage on failure, since we aren't in the + * postmaster process anymore. + */ + oldcontext = MemoryContextSwitchTo(TopMemoryContext); + + /* Handle protocol version 3 startup packet */ + { + int32 offset = sizeof(ProtocolVersion); + List *unrecognized_protocol_options = NIL; + + /* + * Scan packet body for name/option pairs. We can assume any string + * beginning within the packet body is null-terminated, thanks to + * zeroing extra byte above. + */ + port->guc_options = NIL; + + while (offset < len) + { + char *nameptr = buf + offset; + int32 valoffset; + char *valptr; + + if (*nameptr == '\0') + break; /* found packet terminator */ + valoffset = offset + strlen(nameptr) + 1; + if (valoffset >= len) + break; /* missing value, will complain below */ + valptr = buf + valoffset; + + if (strcmp(nameptr, "database") == 0) + port->database_name = pstrdup(valptr); + else if (strcmp(nameptr, "user") == 0) + port->user_name = pstrdup(valptr); + else if (strcmp(nameptr, "options") == 0) + port->cmdline_options = pstrdup(valptr); + else if (strcmp(nameptr, "replication") == 0) + { + /* + * Due to backward compatibility concerns the replication + * parameter is a hybrid beast which allows the value to be + * either boolean or the string 'database'. The latter + * connects to a specific database which is e.g. required for + * logical decoding while. + */ + if (strcmp(valptr, "database") == 0) + { + am_walsender = true; + am_db_walsender = true; + } + else if (!parse_bool(valptr, &am_walsender)) + ereport(FATAL, + (errcode(ERRCODE_INVALID_PARAMETER_VALUE), + errmsg("invalid value for parameter \"%s\": \"%s\"", + "replication", + valptr), + errhint("Valid values are: \"false\", 0, \"true\", 1, \"database\"."))); + } + else if (strncmp(nameptr, "_pq_.", 5) == 0) + { + /* + * Any option beginning with _pq_. is reserved for use as a + * protocol-level option, but at present no such options are + * defined. + */ + unrecognized_protocol_options = + lappend(unrecognized_protocol_options, pstrdup(nameptr)); + } + else + { + /* Assume it's a generic GUC option */ + port->guc_options = lappend(port->guc_options, + pstrdup(nameptr)); + port->guc_options = lappend(port->guc_options, + pstrdup(valptr)); + + /* + * Copy application_name to port if we come across it. This + * is done so we can log the application_name in the + * connection authorization message. Note that the GUC would + * be used but we haven't gone through GUC setup yet. + */ + if (strcmp(nameptr, "application_name") == 0) + { + char *tmp_app_name = pstrdup(valptr); + + pg_clean_ascii(tmp_app_name); + + port->application_name = tmp_app_name; + } + } + offset = valoffset + strlen(valptr) + 1; + } + + /* + * If we didn't find a packet terminator exactly at the end of the + * given packet length, complain. + */ + if (offset != len - 1) + ereport(FATAL, + (errcode(ERRCODE_PROTOCOL_VIOLATION), + errmsg("invalid startup packet layout: expected terminator as last byte"))); + + /* + * If the client requested a newer protocol version or if the client + * requested any protocol options we didn't recognize, let them know + * the newest minor protocol version we do support and the names of + * any unrecognized options. + */ + if (PG_PROTOCOL_MINOR(proto) > PG_PROTOCOL_MINOR(PG_PROTOCOL_LATEST) || + unrecognized_protocol_options != NIL) + SendNegotiateProtocolVersion(unrecognized_protocol_options); + } + + /* Check a user name was given. */ + if (port->user_name == NULL || port->user_name[0] == '\0') + ereport(FATAL, + (errcode(ERRCODE_INVALID_AUTHORIZATION_SPECIFICATION), + errmsg("no PostgreSQL user name specified in startup packet"))); + + /* The database defaults to the user name. */ + if (port->database_name == NULL || port->database_name[0] == '\0') + port->database_name = pstrdup(port->user_name); + + if (Db_user_namespace) + { + /* + * If user@, it is a global user, remove '@'. We only want to do this + * if there is an '@' at the end and no earlier in the user string or + * they may fake as a local user of another database attaching to this + * database. + */ + if (strchr(port->user_name, '@') == + port->user_name + strlen(port->user_name) - 1) + *strchr(port->user_name, '@') = '\0'; + else + { + /* Append '@' and dbname */ + port->user_name = psprintf("%s@%s", port->user_name, port->database_name); + } + } + + /* + * Truncate given database and user names to length of a Postgres name. + * This avoids lookup failures when overlength names are given. + */ + if (strlen(port->database_name) >= NAMEDATALEN) + port->database_name[NAMEDATALEN - 1] = '\0'; + if (strlen(port->user_name) >= NAMEDATALEN) + port->user_name[NAMEDATALEN - 1] = '\0'; + + if (am_walsender) + MyBackendType = B_WAL_SENDER; + else + MyBackendType = B_BACKEND; + + /* + * Normal walsender backends, e.g. for streaming replication, are not + * connected to a particular database. But walsenders used for logical + * replication need to connect to a specific database. We allow streaming + * replication commands to be issued even if connected to a database as it + * can make sense to first make a basebackup and then stream changes + * starting from that. + */ + if (am_walsender && !am_db_walsender) + port->database_name[0] = '\0'; + + /* + * Done putting stuff in TopMemoryContext. + */ + MemoryContextSwitchTo(oldcontext); + + /* + * If we're going to reject the connection due to database state, say so + * now instead of wasting cycles on an authentication exchange. (This also + * allows a pg_ping utility to be written.) + */ + switch (port->canAcceptConnections) + { + case CAC_STARTUP: + ereport(FATAL, + (errcode(ERRCODE_CANNOT_CONNECT_NOW), + errmsg("the database system is starting up"))); + break; + case CAC_NOTCONSISTENT: + if (EnableHotStandby) + ereport(FATAL, + (errcode(ERRCODE_CANNOT_CONNECT_NOW), + errmsg("the database system is not yet accepting connections"), + errdetail("Consistent recovery state has not been yet reached."))); + else + ereport(FATAL, + (errcode(ERRCODE_CANNOT_CONNECT_NOW), + errmsg("the database system is not accepting connections"), + errdetail("Hot standby mode is disabled."))); + break; + case CAC_SHUTDOWN: + ereport(FATAL, + (errcode(ERRCODE_CANNOT_CONNECT_NOW), + errmsg("the database system is shutting down"))); + break; + case CAC_RECOVERY: + ereport(FATAL, + (errcode(ERRCODE_CANNOT_CONNECT_NOW), + errmsg("the database system is in recovery mode"))); + break; + case CAC_TOOMANY: + ereport(FATAL, + (errcode(ERRCODE_TOO_MANY_CONNECTIONS), + errmsg("sorry, too many clients already"))); + break; + case CAC_OK: + break; + } + + return STATUS_OK; +} + +/* + * Send a NegotiateProtocolVersion to the client. This lets the client know + * that they have requested a newer minor protocol version than we are able + * to speak. We'll speak the highest version we know about; the client can, + * of course, abandon the connection if that's a problem. + * + * We also include in the response a list of protocol options we didn't + * understand. This allows clients to include optional parameters that might + * be present either in newer protocol versions or third-party protocol + * extensions without fear of having to reconnect if those options are not + * understood, while at the same time making certain that the client is aware + * of which options were actually accepted. + */ +static void +SendNegotiateProtocolVersion(List *unrecognized_protocol_options) +{ + StringInfoData buf; + ListCell *lc; + + pq_beginmessage(&buf, 'v'); /* NegotiateProtocolVersion */ + pq_sendint32(&buf, PG_PROTOCOL_LATEST); + pq_sendint32(&buf, list_length(unrecognized_protocol_options)); + foreach(lc, unrecognized_protocol_options) + pq_sendstring(&buf, lfirst(lc)); + pq_endmessage(&buf); + + /* no need to flush, some other message will follow */ +} + +/* + * The client has sent a cancel request packet, not a normal + * start-a-new-connection packet. Perform the necessary processing. + * Nothing is sent back to the client. + */ +static void +processCancelRequest(Port *port, void *pkt) +{ + CancelRequestPacket *canc = (CancelRequestPacket *) pkt; + int backendPID; + int32 cancelAuthCode; + Backend *bp; + +#ifndef EXEC_BACKEND + dlist_iter iter; +#else + int i; +#endif + + backendPID = (int) pg_ntoh32(canc->backendPID); + cancelAuthCode = (int32) pg_ntoh32(canc->cancelAuthCode); + + /* + * See if we have a matching backend. In the EXEC_BACKEND case, we can no + * longer access the postmaster's own backend list, and must rely on the + * duplicate array in shared memory. + */ +#ifndef EXEC_BACKEND + dlist_foreach(iter, &BackendList) + { + bp = dlist_container(Backend, elem, iter.cur); +#else + for (i = MaxLivePostmasterChildren() - 1; i >= 0; i--) + { + bp = (Backend *) &ShmemBackendArray[i]; +#endif + if (bp->pid == backendPID) + { + if (bp->cancel_key == cancelAuthCode) + { + /* Found a match; signal that backend to cancel current op */ + ereport(DEBUG2, + (errmsg_internal("processing cancel request: sending SIGINT to process %d", + backendPID))); + signal_child(bp->pid, SIGINT); + } + else + /* Right PID, wrong key: no way, Jose */ + ereport(LOG, + (errmsg("wrong key in cancel request for process %d", + backendPID))); + return; + } +#ifndef EXEC_BACKEND /* make GNU Emacs 26.1 see brace balance */ + } +#else + } +#endif + + /* No matching backend */ + ereport(LOG, + (errmsg("PID %d in cancel request did not match any process", + backendPID))); +} + +/* + * canAcceptConnections --- check to see if database state allows connections + * of the specified type. backend_type can be BACKEND_TYPE_NORMAL, + * BACKEND_TYPE_AUTOVAC, or BACKEND_TYPE_BGWORKER. (Note that we don't yet + * know whether a NORMAL connection might turn into a walsender.) + */ +static CAC_state +canAcceptConnections(int backend_type) +{ + CAC_state result = CAC_OK; + + /* + * Can't start backends when in startup/shutdown/inconsistent recovery + * state. We treat autovac workers the same as user backends for this + * purpose. However, bgworkers are excluded from this test; we expect + * bgworker_should_start_now() decided whether the DB state allows them. + */ + if (pmState != PM_RUN && pmState != PM_HOT_STANDBY && + backend_type != BACKEND_TYPE_BGWORKER) + { + if (Shutdown > NoShutdown) + return CAC_SHUTDOWN; /* shutdown is pending */ + else if (!FatalError && pmState == PM_STARTUP) + return CAC_STARTUP; /* normal startup */ + else if (!FatalError && pmState == PM_RECOVERY) + return CAC_NOTCONSISTENT; /* not yet at consistent recovery + * state */ + else + return CAC_RECOVERY; /* else must be crash recovery */ + } + + /* + * "Smart shutdown" restrictions are applied only to normal connections, + * not to autovac workers or bgworkers. + */ + if (!connsAllowed && backend_type == BACKEND_TYPE_NORMAL) + return CAC_SHUTDOWN; /* shutdown is pending */ + + /* + * Don't start too many children. + * + * We allow more connections here than we can have backends because some + * might still be authenticating; they might fail auth, or some existing + * backend might exit before the auth cycle is completed. The exact + * MaxBackends limit is enforced when a new backend tries to join the + * shared-inval backend array. + * + * The limit here must match the sizes of the per-child-process arrays; + * see comments for MaxLivePostmasterChildren(). + */ + if (CountChildren(BACKEND_TYPE_ALL) >= MaxLivePostmasterChildren()) + result = CAC_TOOMANY; + + return result; +} + + +/* + * ConnCreate -- create a local connection data structure + * + * Returns NULL on failure, other than out-of-memory which is fatal. + */ +static Port * +ConnCreate(int serverFd) +{ + Port *port; + + if (!(port = (Port *) calloc(1, sizeof(Port)))) + { + ereport(LOG, + (errcode(ERRCODE_OUT_OF_MEMORY), + errmsg("out of memory"))); + ExitPostmaster(1); + } + + if (StreamConnection(serverFd, port) != STATUS_OK) + { + if (port->sock != PGINVALID_SOCKET) + StreamClose(port->sock); + ConnFree(port); + return NULL; + } + + return port; +} + + +/* + * ConnFree -- free a local connection data structure + * + * Caller has already closed the socket if any, so there's not much + * to do here. + */ +static void +ConnFree(Port *conn) +{ + free(conn); +} + + +/* + * ClosePostmasterPorts -- close all the postmaster's open sockets + * + * This is called during child process startup to release file descriptors + * that are not needed by that child process. The postmaster still has + * them open, of course. + * + * Note: we pass am_syslogger as a boolean because we don't want to set + * the global variable yet when this is called. + */ +void +ClosePostmasterPorts(bool am_syslogger) +{ + int i; + +#ifndef WIN32 + + /* + * Close the write end of postmaster death watch pipe. It's important to + * do this as early as possible, so that if postmaster dies, others won't + * think that it's still running because we're holding the pipe open. + */ + if (close(postmaster_alive_fds[POSTMASTER_FD_OWN]) != 0) + ereport(FATAL, + (errcode_for_file_access(), + errmsg_internal("could not close postmaster death monitoring pipe in child process: %m"))); + postmaster_alive_fds[POSTMASTER_FD_OWN] = -1; + /* Notify fd.c that we released one pipe FD. */ + ReleaseExternalFD(); +#endif + + /* + * Close the postmaster's listen sockets. These aren't tracked by fd.c, + * so we don't call ReleaseExternalFD() here. + */ + for (i = 0; i < MAXLISTEN; i++) + { + if (ListenSocket[i] != PGINVALID_SOCKET) + { + StreamClose(ListenSocket[i]); + ListenSocket[i] = PGINVALID_SOCKET; + } + } + + /* + * If using syslogger, close the read side of the pipe. We don't bother + * tracking this in fd.c, either. + */ + if (!am_syslogger) + { +#ifndef WIN32 + if (syslogPipe[0] >= 0) + close(syslogPipe[0]); + syslogPipe[0] = -1; +#else + if (syslogPipe[0]) + CloseHandle(syslogPipe[0]); + syslogPipe[0] = 0; +#endif + } + +#ifdef USE_BONJOUR + /* If using Bonjour, close the connection to the mDNS daemon */ + if (bonjour_sdref) + close(DNSServiceRefSockFD(bonjour_sdref)); +#endif +} + + +/* + * InitProcessGlobals -- set MyProcPid, MyStartTime[stamp], random seeds + * + * Called early in the postmaster and every backend. + */ +void +InitProcessGlobals(void) +{ + MyProcPid = getpid(); + MyStartTimestamp = GetCurrentTimestamp(); + MyStartTime = timestamptz_to_time_t(MyStartTimestamp); + + /* + * Set a different global seed in every process. We want something + * unpredictable, so if possible, use high-quality random bits for the + * seed. Otherwise, fall back to a seed based on timestamp and PID. + */ + if (unlikely(!pg_prng_strong_seed(&pg_global_prng_state))) + { + uint64 rseed; + + /* + * Since PIDs and timestamps tend to change more frequently in their + * least significant bits, shift the timestamp left to allow a larger + * total number of seeds in a given time period. Since that would + * leave only 20 bits of the timestamp that cycle every ~1 second, + * also mix in some higher bits. + */ + rseed = ((uint64) MyProcPid) ^ + ((uint64) MyStartTimestamp << 12) ^ + ((uint64) MyStartTimestamp >> 20); + + pg_prng_seed(&pg_global_prng_state, rseed); + } + + /* + * Also make sure that we've set a good seed for random(3). Use of that + * is deprecated in core Postgres, but extensions might use it. + */ +#ifndef WIN32 + srandom(pg_prng_uint32(&pg_global_prng_state)); +#endif +} + + +/* + * reset_shared -- reset shared memory and semaphores + */ +static void +reset_shared(void) +{ + /* + * Create or re-create shared memory and semaphores. + * + * Note: in each "cycle of life" we will normally assign the same IPC keys + * (if using SysV shmem and/or semas). This helps ensure that we will + * clean up dead IPC objects if the postmaster crashes and is restarted. + */ + CreateSharedMemoryAndSemaphores(); +} + + +/* + * SIGHUP -- reread config files, and tell children to do same + */ +static void +SIGHUP_handler(SIGNAL_ARGS) +{ + int save_errno = errno; + + /* + * We rely on the signal mechanism to have blocked all signals ... except + * on Windows, which lacks sigaction(), so we have to do it manually. + */ +#ifdef WIN32 + PG_SETMASK(&BlockSig); +#endif + + if (Shutdown <= SmartShutdown) + { + ereport(LOG, + (errmsg("received SIGHUP, reloading configuration files"))); + ProcessConfigFile(PGC_SIGHUP); + SignalChildren(SIGHUP); + if (StartupPID != 0) + signal_child(StartupPID, SIGHUP); + if (BgWriterPID != 0) + signal_child(BgWriterPID, SIGHUP); + if (CheckpointerPID != 0) + signal_child(CheckpointerPID, SIGHUP); + if (WalWriterPID != 0) + signal_child(WalWriterPID, SIGHUP); + if (WalReceiverPID != 0) + signal_child(WalReceiverPID, SIGHUP); + if (AutoVacPID != 0) + signal_child(AutoVacPID, SIGHUP); + if (PgArchPID != 0) + signal_child(PgArchPID, SIGHUP); + if (SysLoggerPID != 0) + signal_child(SysLoggerPID, SIGHUP); + + /* Reload authentication config files too */ + if (!load_hba()) + ereport(LOG, + /* translator: %s is a configuration file */ + (errmsg("%s was not reloaded", "pg_hba.conf"))); + + if (!load_ident()) + ereport(LOG, + (errmsg("%s was not reloaded", "pg_ident.conf"))); + +#ifdef USE_SSL + /* Reload SSL configuration as well */ + if (EnableSSL) + { + if (secure_initialize(false) == 0) + LoadedSSL = true; + else + ereport(LOG, + (errmsg("SSL configuration was not reloaded"))); + } + else + { + secure_destroy(); + LoadedSSL = false; + } +#endif + +#ifdef EXEC_BACKEND + /* Update the starting-point file for future children */ + write_nondefault_variables(PGC_SIGHUP); +#endif + } + +#ifdef WIN32 + PG_SETMASK(&UnBlockSig); +#endif + + errno = save_errno; +} + + +/* + * pmdie -- signal handler for processing various postmaster signals. + */ +static void +pmdie(SIGNAL_ARGS) +{ + int save_errno = errno; + + /* + * We rely on the signal mechanism to have blocked all signals ... except + * on Windows, which lacks sigaction(), so we have to do it manually. + */ +#ifdef WIN32 + PG_SETMASK(&BlockSig); +#endif + + ereport(DEBUG2, + (errmsg_internal("postmaster received signal %d", + postgres_signal_arg))); + + switch (postgres_signal_arg) + { + case SIGTERM: + + /* + * Smart Shutdown: + * + * Wait for children to end their work, then shut down. + */ + if (Shutdown >= SmartShutdown) + break; + Shutdown = SmartShutdown; + ereport(LOG, + (errmsg("received smart shutdown request"))); + + /* Report status */ + AddToDataDirLockFile(LOCK_FILE_LINE_PM_STATUS, PM_STATUS_STOPPING); +#ifdef USE_SYSTEMD + sd_notify(0, "STOPPING=1"); +#endif + + /* + * If we reached normal running, we go straight to waiting for + * client backends to exit. If already in PM_STOP_BACKENDS or a + * later state, do not change it. + */ + if (pmState == PM_RUN || pmState == PM_HOT_STANDBY) + connsAllowed = false; + else if (pmState == PM_STARTUP || pmState == PM_RECOVERY) + { + /* There should be no clients, so proceed to stop children */ + pmState = PM_STOP_BACKENDS; + } + + /* + * Now wait for online backup mode to end and backends to exit. If + * that is already the case, PostmasterStateMachine will take the + * next step. + */ + PostmasterStateMachine(); + break; + + case SIGINT: + + /* + * Fast Shutdown: + * + * Abort all children with SIGTERM (rollback active transactions + * and exit) and shut down when they are gone. + */ + if (Shutdown >= FastShutdown) + break; + Shutdown = FastShutdown; + ereport(LOG, + (errmsg("received fast shutdown request"))); + + /* Report status */ + AddToDataDirLockFile(LOCK_FILE_LINE_PM_STATUS, PM_STATUS_STOPPING); +#ifdef USE_SYSTEMD + sd_notify(0, "STOPPING=1"); +#endif + + if (pmState == PM_STARTUP || pmState == PM_RECOVERY) + { + /* Just shut down background processes silently */ + pmState = PM_STOP_BACKENDS; + } + else if (pmState == PM_RUN || + pmState == PM_HOT_STANDBY) + { + /* Report that we're about to zap live client sessions */ + ereport(LOG, + (errmsg("aborting any active transactions"))); + pmState = PM_STOP_BACKENDS; + } + + /* + * PostmasterStateMachine will issue any necessary signals, or + * take the next step if no child processes need to be killed. + */ + PostmasterStateMachine(); + break; + + case SIGQUIT: + + /* + * Immediate Shutdown: + * + * abort all children with SIGQUIT, wait for them to exit, + * terminate remaining ones with SIGKILL, then exit without + * attempt to properly shut down the data base system. + */ + if (Shutdown >= ImmediateShutdown) + break; + Shutdown = ImmediateShutdown; + ereport(LOG, + (errmsg("received immediate shutdown request"))); + + /* Report status */ + AddToDataDirLockFile(LOCK_FILE_LINE_PM_STATUS, PM_STATUS_STOPPING); +#ifdef USE_SYSTEMD + sd_notify(0, "STOPPING=1"); +#endif + + /* tell children to shut down ASAP */ + SetQuitSignalReason(PMQUIT_FOR_STOP); + TerminateChildren(SIGQUIT); + pmState = PM_WAIT_BACKENDS; + + /* set stopwatch for them to die */ + AbortStartTime = time(NULL); + + /* + * Now wait for backends to exit. If there are none, + * PostmasterStateMachine will take the next step. + */ + PostmasterStateMachine(); + break; + } + +#ifdef WIN32 + PG_SETMASK(&UnBlockSig); +#endif + + errno = save_errno; +} + +/* + * Reaper -- signal handler to cleanup after a child process dies. + */ +static void +reaper(SIGNAL_ARGS) +{ + int save_errno = errno; + int pid; /* process id of dead child process */ + int exitstatus; /* its exit status */ + + /* + * We rely on the signal mechanism to have blocked all signals ... except + * on Windows, which lacks sigaction(), so we have to do it manually. + */ +#ifdef WIN32 + PG_SETMASK(&BlockSig); +#endif + + ereport(DEBUG4, + (errmsg_internal("reaping dead processes"))); + + while ((pid = waitpid(-1, &exitstatus, WNOHANG)) > 0) + { + /* + * Check if this child was a startup process. + */ + if (pid == StartupPID) + { + StartupPID = 0; + + /* + * Startup process exited in response to a shutdown request (or it + * completed normally regardless of the shutdown request). + */ + if (Shutdown > NoShutdown && + (EXIT_STATUS_0(exitstatus) || EXIT_STATUS_1(exitstatus))) + { + StartupStatus = STARTUP_NOT_RUNNING; + pmState = PM_WAIT_BACKENDS; + /* PostmasterStateMachine logic does the rest */ + continue; + } + + if (EXIT_STATUS_3(exitstatus)) + { + ereport(LOG, + (errmsg("shutdown at recovery target"))); + StartupStatus = STARTUP_NOT_RUNNING; + Shutdown = Max(Shutdown, SmartShutdown); + TerminateChildren(SIGTERM); + pmState = PM_WAIT_BACKENDS; + /* PostmasterStateMachine logic does the rest */ + continue; + } + + /* + * Unexpected exit of startup process (including FATAL exit) + * during PM_STARTUP is treated as catastrophic. There are no + * other processes running yet, so we can just exit. + */ + if (pmState == PM_STARTUP && + StartupStatus != STARTUP_SIGNALED && + !EXIT_STATUS_0(exitstatus)) + { + LogChildExit(LOG, _("startup process"), + pid, exitstatus); + ereport(LOG, + (errmsg("aborting startup due to startup process failure"))); + ExitPostmaster(1); + } + + /* + * After PM_STARTUP, any unexpected exit (including FATAL exit) of + * the startup process is catastrophic, so kill other children, + * and set StartupStatus so we don't try to reinitialize after + * they're gone. Exception: if StartupStatus is STARTUP_SIGNALED, + * then we previously sent the startup process a SIGQUIT; so + * that's probably the reason it died, and we do want to try to + * restart in that case. + * + * This stanza also handles the case where we sent a SIGQUIT + * during PM_STARTUP due to some dead_end child crashing: in that + * situation, if the startup process dies on the SIGQUIT, we need + * to transition to PM_WAIT_BACKENDS state which will allow + * PostmasterStateMachine to restart the startup process. (On the + * other hand, the startup process might complete normally, if we + * were too late with the SIGQUIT. In that case we'll fall + * through and commence normal operations.) + */ + if (!EXIT_STATUS_0(exitstatus)) + { + if (StartupStatus == STARTUP_SIGNALED) + { + StartupStatus = STARTUP_NOT_RUNNING; + if (pmState == PM_STARTUP) + pmState = PM_WAIT_BACKENDS; + } + else + StartupStatus = STARTUP_CRASHED; + HandleChildCrash(pid, exitstatus, + _("startup process")); + continue; + } + + /* + * Startup succeeded, commence normal operations + */ + StartupStatus = STARTUP_NOT_RUNNING; + FatalError = false; + AbortStartTime = 0; + ReachedNormalRunning = true; + pmState = PM_RUN; + connsAllowed = true; + + /* + * Crank up the background tasks, if we didn't do that already + * when we entered consistent recovery state. It doesn't matter + * if this fails, we'll just try again later. + */ + if (CheckpointerPID == 0) + CheckpointerPID = StartCheckpointer(); + if (BgWriterPID == 0) + BgWriterPID = StartBackgroundWriter(); + if (WalWriterPID == 0) + WalWriterPID = StartWalWriter(); + + /* + * Likewise, start other special children as needed. In a restart + * situation, some of them may be alive already. + */ + if (!IsBinaryUpgrade && AutoVacuumingActive() && AutoVacPID == 0) + AutoVacPID = StartAutoVacLauncher(); + if (PgArchStartupAllowed() && PgArchPID == 0) + PgArchPID = StartArchiver(); + + /* workers may be scheduled to start now */ + maybe_start_bgworkers(); + + /* at this point we are really open for business */ + ereport(LOG, + (errmsg("database system is ready to accept connections"))); + + /* Report status */ + AddToDataDirLockFile(LOCK_FILE_LINE_PM_STATUS, PM_STATUS_READY); +#ifdef USE_SYSTEMD + sd_notify(0, "READY=1"); +#endif + + continue; + } + + /* + * Was it the bgwriter? Normal exit can be ignored; we'll start a new + * one at the next iteration of the postmaster's main loop, if + * necessary. Any other exit condition is treated as a crash. + */ + if (pid == BgWriterPID) + { + BgWriterPID = 0; + if (!EXIT_STATUS_0(exitstatus)) + HandleChildCrash(pid, exitstatus, + _("background writer process")); + continue; + } + + /* + * Was it the checkpointer? + */ + if (pid == CheckpointerPID) + { + CheckpointerPID = 0; + if (EXIT_STATUS_0(exitstatus) && pmState == PM_SHUTDOWN) + { + /* + * OK, we saw normal exit of the checkpointer after it's been + * told to shut down. We expect that it wrote a shutdown + * checkpoint. (If for some reason it didn't, recovery will + * occur on next postmaster start.) + * + * At this point we should have no normal backend children + * left (else we'd not be in PM_SHUTDOWN state) but we might + * have dead_end children to wait for. + * + * If we have an archiver subprocess, tell it to do a last + * archive cycle and quit. Likewise, if we have walsender + * processes, tell them to send any remaining WAL and quit. + */ + Assert(Shutdown > NoShutdown); + + /* Waken archiver for the last time */ + if (PgArchPID != 0) + signal_child(PgArchPID, SIGUSR2); + + /* + * Waken walsenders for the last time. No regular backends + * should be around anymore. + */ + SignalChildren(SIGUSR2); + + pmState = PM_SHUTDOWN_2; + } + else + { + /* + * Any unexpected exit of the checkpointer (including FATAL + * exit) is treated as a crash. + */ + HandleChildCrash(pid, exitstatus, + _("checkpointer process")); + } + + continue; + } + + /* + * Was it the wal writer? Normal exit can be ignored; we'll start a + * new one at the next iteration of the postmaster's main loop, if + * necessary. Any other exit condition is treated as a crash. + */ + if (pid == WalWriterPID) + { + WalWriterPID = 0; + if (!EXIT_STATUS_0(exitstatus)) + HandleChildCrash(pid, exitstatus, + _("WAL writer process")); + continue; + } + + /* + * Was it the wal receiver? If exit status is zero (normal) or one + * (FATAL exit), we assume everything is all right just like normal + * backends. (If we need a new wal receiver, we'll start one at the + * next iteration of the postmaster's main loop.) + */ + if (pid == WalReceiverPID) + { + WalReceiverPID = 0; + if (!EXIT_STATUS_0(exitstatus) && !EXIT_STATUS_1(exitstatus)) + HandleChildCrash(pid, exitstatus, + _("WAL receiver process")); + continue; + } + + /* + * Was it the autovacuum launcher? Normal exit can be ignored; we'll + * start a new one at the next iteration of the postmaster's main + * loop, if necessary. Any other exit condition is treated as a + * crash. + */ + if (pid == AutoVacPID) + { + AutoVacPID = 0; + if (!EXIT_STATUS_0(exitstatus)) + HandleChildCrash(pid, exitstatus, + _("autovacuum launcher process")); + continue; + } + + /* + * Was it the archiver? If exit status is zero (normal) or one (FATAL + * exit), we assume everything is all right just like normal backends + * and just try to restart a new one so that we immediately retry + * archiving remaining files. (If fail, we'll try again in future + * cycles of the postmaster's main loop.) Unless we were waiting for + * it to shut down; don't restart it in that case, and + * PostmasterStateMachine() will advance to the next shutdown step. + */ + if (pid == PgArchPID) + { + PgArchPID = 0; + if (!EXIT_STATUS_0(exitstatus) && !EXIT_STATUS_1(exitstatus)) + HandleChildCrash(pid, exitstatus, + _("archiver process")); + if (PgArchStartupAllowed()) + PgArchPID = StartArchiver(); + continue; + } + + /* Was it the system logger? If so, try to start a new one */ + if (pid == SysLoggerPID) + { + SysLoggerPID = 0; + /* for safety's sake, launch new logger *first* */ + SysLoggerPID = SysLogger_Start(); + if (!EXIT_STATUS_0(exitstatus)) + LogChildExit(LOG, _("system logger process"), + pid, exitstatus); + continue; + } + + /* Was it one of our background workers? */ + if (CleanupBackgroundWorker(pid, exitstatus)) + { + /* have it be restarted */ + HaveCrashedWorker = true; + continue; + } + + /* + * Else do standard backend child cleanup. + */ + CleanupBackend(pid, exitstatus); + } /* loop over pending child-death reports */ + + /* + * After cleaning out the SIGCHLD queue, see if we have any state changes + * or actions to make. + */ + PostmasterStateMachine(); + + /* Done with signal handler */ +#ifdef WIN32 + PG_SETMASK(&UnBlockSig); +#endif + + errno = save_errno; +} + +/* + * Scan the bgworkers list and see if the given PID (which has just stopped + * or crashed) is in it. Handle its shutdown if so, and return true. If not a + * bgworker, return false. + * + * This is heavily based on CleanupBackend. One important difference is that + * we don't know yet that the dying process is a bgworker, so we must be silent + * until we're sure it is. + */ +static bool +CleanupBackgroundWorker(int pid, + int exitstatus) /* child's exit status */ +{ + char namebuf[MAXPGPATH]; + slist_mutable_iter iter; + + slist_foreach_modify(iter, &BackgroundWorkerList) + { + RegisteredBgWorker *rw; + + rw = slist_container(RegisteredBgWorker, rw_lnode, iter.cur); + + if (rw->rw_pid != pid) + continue; + +#ifdef WIN32 + /* see CleanupBackend */ + if (exitstatus == ERROR_WAIT_NO_CHILDREN) + exitstatus = 0; +#endif + + snprintf(namebuf, MAXPGPATH, _("background worker \"%s\""), + rw->rw_worker.bgw_type); + + + if (!EXIT_STATUS_0(exitstatus)) + { + /* Record timestamp, so we know when to restart the worker. */ + rw->rw_crashed_at = GetCurrentTimestamp(); + } + else + { + /* Zero exit status means terminate */ + rw->rw_crashed_at = 0; + rw->rw_terminate = true; + } + + /* + * Additionally, just like a backend, any exit status other than 0 or + * 1 is considered a crash and causes a system-wide restart. + */ + if (!EXIT_STATUS_0(exitstatus) && !EXIT_STATUS_1(exitstatus)) + { + HandleChildCrash(pid, exitstatus, namebuf); + return true; + } + + /* + * We must release the postmaster child slot. If the worker failed to + * do so, it did not clean up after itself, requiring a crash-restart + * cycle. + */ + if (!ReleasePostmasterChildSlot(rw->rw_child_slot)) + { + HandleChildCrash(pid, exitstatus, namebuf); + return true; + } + + /* Get it out of the BackendList and clear out remaining data */ + dlist_delete(&rw->rw_backend->elem); +#ifdef EXEC_BACKEND + ShmemBackendArrayRemove(rw->rw_backend); +#endif + + /* + * It's possible that this background worker started some OTHER + * background worker and asked to be notified when that worker started + * or stopped. If so, cancel any notifications destined for the + * now-dead backend. + */ + if (rw->rw_backend->bgworker_notify) + BackgroundWorkerStopNotifications(rw->rw_pid); + free(rw->rw_backend); + rw->rw_backend = NULL; + rw->rw_pid = 0; + rw->rw_child_slot = 0; + ReportBackgroundWorkerExit(&iter); /* report child death */ + + LogChildExit(EXIT_STATUS_0(exitstatus) ? DEBUG1 : LOG, + namebuf, pid, exitstatus); + + return true; + } + + return false; +} + +/* + * CleanupBackend -- cleanup after terminated backend. + * + * Remove all local state associated with backend. + * + * If you change this, see also CleanupBackgroundWorker. + */ +static void +CleanupBackend(int pid, + int exitstatus) /* child's exit status. */ +{ + dlist_mutable_iter iter; + + LogChildExit(DEBUG2, _("server process"), pid, exitstatus); + + /* + * If a backend dies in an ugly way then we must signal all other backends + * to quickdie. If exit status is zero (normal) or one (FATAL exit), we + * assume everything is all right and proceed to remove the backend from + * the active backend list. + */ + +#ifdef WIN32 + + /* + * On win32, also treat ERROR_WAIT_NO_CHILDREN (128) as nonfatal case, + * since that sometimes happens under load when the process fails to start + * properly (long before it starts using shared memory). Microsoft reports + * it is related to mutex failure: + * http://archives.postgresql.org/pgsql-hackers/2010-09/msg00790.php + */ + if (exitstatus == ERROR_WAIT_NO_CHILDREN) + { + LogChildExit(LOG, _("server process"), pid, exitstatus); + exitstatus = 0; + } +#endif + + if (!EXIT_STATUS_0(exitstatus) && !EXIT_STATUS_1(exitstatus)) + { + HandleChildCrash(pid, exitstatus, _("server process")); + return; + } + + dlist_foreach_modify(iter, &BackendList) + { + Backend *bp = dlist_container(Backend, elem, iter.cur); + + if (bp->pid == pid) + { + if (!bp->dead_end) + { + if (!ReleasePostmasterChildSlot(bp->child_slot)) + { + /* + * Uh-oh, the child failed to clean itself up. Treat as a + * crash after all. + */ + HandleChildCrash(pid, exitstatus, _("server process")); + return; + } +#ifdef EXEC_BACKEND + ShmemBackendArrayRemove(bp); +#endif + } + if (bp->bgworker_notify) + { + /* + * This backend may have been slated to receive SIGUSR1 when + * some background worker started or stopped. Cancel those + * notifications, as we don't want to signal PIDs that are not + * PostgreSQL backends. This gets skipped in the (probably + * very common) case where the backend has never requested any + * such notifications. + */ + BackgroundWorkerStopNotifications(bp->pid); + } + dlist_delete(iter.cur); + free(bp); + break; + } + } +} + +/* + * HandleChildCrash -- cleanup after failed backend, bgwriter, checkpointer, + * walwriter, autovacuum, archiver or background worker. + * + * The objectives here are to clean up our local state about the child + * process, and to signal all other remaining children to quickdie. + */ +static void +HandleChildCrash(int pid, int exitstatus, const char *procname) +{ + dlist_mutable_iter iter; + slist_iter siter; + Backend *bp; + bool take_action; + + /* + * We only log messages and send signals if this is the first process + * crash and we're not doing an immediate shutdown; otherwise, we're only + * here to update postmaster's idea of live processes. If we have already + * signaled children, nonzero exit status is to be expected, so don't + * clutter log. + */ + take_action = !FatalError && Shutdown != ImmediateShutdown; + + if (take_action) + { + LogChildExit(LOG, procname, pid, exitstatus); + ereport(LOG, + (errmsg("terminating any other active server processes"))); + SetQuitSignalReason(PMQUIT_FOR_CRASH); + } + + /* Process background workers. */ + slist_foreach(siter, &BackgroundWorkerList) + { + RegisteredBgWorker *rw; + + rw = slist_container(RegisteredBgWorker, rw_lnode, siter.cur); + if (rw->rw_pid == 0) + continue; /* not running */ + if (rw->rw_pid == pid) + { + /* + * Found entry for freshly-dead worker, so remove it. + */ + (void) ReleasePostmasterChildSlot(rw->rw_child_slot); + dlist_delete(&rw->rw_backend->elem); +#ifdef EXEC_BACKEND + ShmemBackendArrayRemove(rw->rw_backend); +#endif + free(rw->rw_backend); + rw->rw_backend = NULL; + rw->rw_pid = 0; + rw->rw_child_slot = 0; + /* don't reset crashed_at */ + /* don't report child stop, either */ + /* Keep looping so we can signal remaining workers */ + } + else + { + /* + * This worker is still alive. Unless we did so already, tell it + * to commit hara-kiri. + * + * SIGQUIT is the special signal that says exit without proc_exit + * and let the user know what's going on. But if SendStop is set + * (-T on command line), then we send SIGSTOP instead, so that we + * can get core dumps from all backends by hand. + */ + if (take_action) + { + ereport(DEBUG2, + (errmsg_internal("sending %s to process %d", + (SendStop ? "SIGSTOP" : "SIGQUIT"), + (int) rw->rw_pid))); + signal_child(rw->rw_pid, (SendStop ? SIGSTOP : SIGQUIT)); + } + } + } + + /* Process regular backends */ + dlist_foreach_modify(iter, &BackendList) + { + bp = dlist_container(Backend, elem, iter.cur); + + if (bp->pid == pid) + { + /* + * Found entry for freshly-dead backend, so remove it. + */ + if (!bp->dead_end) + { + (void) ReleasePostmasterChildSlot(bp->child_slot); +#ifdef EXEC_BACKEND + ShmemBackendArrayRemove(bp); +#endif + } + dlist_delete(iter.cur); + free(bp); + /* Keep looping so we can signal remaining backends */ + } + else + { + /* + * This backend is still alive. Unless we did so already, tell it + * to commit hara-kiri. + * + * SIGQUIT is the special signal that says exit without proc_exit + * and let the user know what's going on. But if SendStop is set + * (-T on command line), then we send SIGSTOP instead, so that we + * can get core dumps from all backends by hand. + * + * We could exclude dead_end children here, but at least in the + * SIGSTOP case it seems better to include them. + * + * Background workers were already processed above; ignore them + * here. + */ + if (bp->bkend_type == BACKEND_TYPE_BGWORKER) + continue; + + if (take_action) + { + ereport(DEBUG2, + (errmsg_internal("sending %s to process %d", + (SendStop ? "SIGSTOP" : "SIGQUIT"), + (int) bp->pid))); + signal_child(bp->pid, (SendStop ? SIGSTOP : SIGQUIT)); + } + } + } + + /* Take care of the startup process too */ + if (pid == StartupPID) + { + StartupPID = 0; + /* Caller adjusts StartupStatus, so don't touch it here */ + } + else if (StartupPID != 0 && take_action) + { + ereport(DEBUG2, + (errmsg_internal("sending %s to process %d", + (SendStop ? "SIGSTOP" : "SIGQUIT"), + (int) StartupPID))); + signal_child(StartupPID, (SendStop ? SIGSTOP : SIGQUIT)); + StartupStatus = STARTUP_SIGNALED; + } + + /* Take care of the bgwriter too */ + if (pid == BgWriterPID) + BgWriterPID = 0; + else if (BgWriterPID != 0 && take_action) + { + ereport(DEBUG2, + (errmsg_internal("sending %s to process %d", + (SendStop ? "SIGSTOP" : "SIGQUIT"), + (int) BgWriterPID))); + signal_child(BgWriterPID, (SendStop ? SIGSTOP : SIGQUIT)); + } + + /* Take care of the checkpointer too */ + if (pid == CheckpointerPID) + CheckpointerPID = 0; + else if (CheckpointerPID != 0 && take_action) + { + ereport(DEBUG2, + (errmsg_internal("sending %s to process %d", + (SendStop ? "SIGSTOP" : "SIGQUIT"), + (int) CheckpointerPID))); + signal_child(CheckpointerPID, (SendStop ? SIGSTOP : SIGQUIT)); + } + + /* Take care of the walwriter too */ + if (pid == WalWriterPID) + WalWriterPID = 0; + else if (WalWriterPID != 0 && take_action) + { + ereport(DEBUG2, + (errmsg_internal("sending %s to process %d", + (SendStop ? "SIGSTOP" : "SIGQUIT"), + (int) WalWriterPID))); + signal_child(WalWriterPID, (SendStop ? SIGSTOP : SIGQUIT)); + } + + /* Take care of the walreceiver too */ + if (pid == WalReceiverPID) + WalReceiverPID = 0; + else if (WalReceiverPID != 0 && take_action) + { + ereport(DEBUG2, + (errmsg_internal("sending %s to process %d", + (SendStop ? "SIGSTOP" : "SIGQUIT"), + (int) WalReceiverPID))); + signal_child(WalReceiverPID, (SendStop ? SIGSTOP : SIGQUIT)); + } + + /* Take care of the autovacuum launcher too */ + if (pid == AutoVacPID) + AutoVacPID = 0; + else if (AutoVacPID != 0 && take_action) + { + ereport(DEBUG2, + (errmsg_internal("sending %s to process %d", + (SendStop ? "SIGSTOP" : "SIGQUIT"), + (int) AutoVacPID))); + signal_child(AutoVacPID, (SendStop ? SIGSTOP : SIGQUIT)); + } + + /* Take care of the archiver too */ + if (pid == PgArchPID) + PgArchPID = 0; + else if (PgArchPID != 0 && take_action) + { + ereport(DEBUG2, + (errmsg_internal("sending %s to process %d", + (SendStop ? "SIGSTOP" : "SIGQUIT"), + (int) PgArchPID))); + signal_child(PgArchPID, (SendStop ? SIGSTOP : SIGQUIT)); + } + + /* We do NOT restart the syslogger */ + + if (Shutdown != ImmediateShutdown) + FatalError = true; + + /* We now transit into a state of waiting for children to die */ + if (pmState == PM_RECOVERY || + pmState == PM_HOT_STANDBY || + pmState == PM_RUN || + pmState == PM_STOP_BACKENDS || + pmState == PM_SHUTDOWN) + pmState = PM_WAIT_BACKENDS; + + /* + * .. and if this doesn't happen quickly enough, now the clock is ticking + * for us to kill them without mercy. + */ + if (AbortStartTime == 0) + AbortStartTime = time(NULL); +} + +/* + * Log the death of a child process. + */ +static void +LogChildExit(int lev, const char *procname, int pid, int exitstatus) +{ + /* + * size of activity_buffer is arbitrary, but set equal to default + * track_activity_query_size + */ + char activity_buffer[1024]; + const char *activity = NULL; + + if (!EXIT_STATUS_0(exitstatus)) + activity = pgstat_get_crashed_backend_activity(pid, + activity_buffer, + sizeof(activity_buffer)); + + if (WIFEXITED(exitstatus)) + ereport(lev, + + /*------ + translator: %s is a noun phrase describing a child process, such as + "server process" */ + (errmsg("%s (PID %d) exited with exit code %d", + procname, pid, WEXITSTATUS(exitstatus)), + activity ? errdetail("Failed process was running: %s", activity) : 0)); + else if (WIFSIGNALED(exitstatus)) + { +#if defined(WIN32) + ereport(lev, + + /*------ + translator: %s is a noun phrase describing a child process, such as + "server process" */ + (errmsg("%s (PID %d) was terminated by exception 0x%X", + procname, pid, WTERMSIG(exitstatus)), + errhint("See C include file \"ntstatus.h\" for a description of the hexadecimal value."), + activity ? errdetail("Failed process was running: %s", activity) : 0)); +#else + ereport(lev, + + /*------ + translator: %s is a noun phrase describing a child process, such as + "server process" */ + (errmsg("%s (PID %d) was terminated by signal %d: %s", + procname, pid, WTERMSIG(exitstatus), + pg_strsignal(WTERMSIG(exitstatus))), + activity ? errdetail("Failed process was running: %s", activity) : 0)); +#endif + } + else + ereport(lev, + + /*------ + translator: %s is a noun phrase describing a child process, such as + "server process" */ + (errmsg("%s (PID %d) exited with unrecognized status %d", + procname, pid, exitstatus), + activity ? errdetail("Failed process was running: %s", activity) : 0)); +} + +/* + * Advance the postmaster's state machine and take actions as appropriate + * + * This is common code for pmdie(), reaper() and sigusr1_handler(), which + * receive the signals that might mean we need to change state. + */ +static void +PostmasterStateMachine(void) +{ + /* If we're doing a smart shutdown, try to advance that state. */ + if (pmState == PM_RUN || pmState == PM_HOT_STANDBY) + { + if (!connsAllowed) + { + /* + * This state ends when we have no normal client backends running. + * Then we're ready to stop other children. + */ + if (CountChildren(BACKEND_TYPE_NORMAL) == 0) + pmState = PM_STOP_BACKENDS; + } + } + + /* + * If we're ready to do so, signal child processes to shut down. (This + * isn't a persistent state, but treating it as a distinct pmState allows + * us to share this code across multiple shutdown code paths.) + */ + if (pmState == PM_STOP_BACKENDS) + { + /* + * Forget any pending requests for background workers, since we're no + * longer willing to launch any new workers. (If additional requests + * arrive, BackgroundWorkerStateChange will reject them.) + */ + ForgetUnstartedBackgroundWorkers(); + + /* Signal all backend children except walsenders */ + SignalSomeChildren(SIGTERM, + BACKEND_TYPE_ALL - BACKEND_TYPE_WALSND); + /* and the autovac launcher too */ + if (AutoVacPID != 0) + signal_child(AutoVacPID, SIGTERM); + /* and the bgwriter too */ + if (BgWriterPID != 0) + signal_child(BgWriterPID, SIGTERM); + /* and the walwriter too */ + if (WalWriterPID != 0) + signal_child(WalWriterPID, SIGTERM); + /* If we're in recovery, also stop startup and walreceiver procs */ + if (StartupPID != 0) + signal_child(StartupPID, SIGTERM); + if (WalReceiverPID != 0) + signal_child(WalReceiverPID, SIGTERM); + /* checkpointer, archiver, stats, and syslogger may continue for now */ + + /* Now transition to PM_WAIT_BACKENDS state to wait for them to die */ + pmState = PM_WAIT_BACKENDS; + } + + /* + * If we are in a state-machine state that implies waiting for backends to + * exit, see if they're all gone, and change state if so. + */ + if (pmState == PM_WAIT_BACKENDS) + { + /* + * PM_WAIT_BACKENDS state ends when we have no regular backends + * (including autovac workers), no bgworkers (including unconnected + * ones), and no walwriter, autovac launcher or bgwriter. If we are + * doing crash recovery or an immediate shutdown then we expect the + * checkpointer to exit as well, otherwise not. The stats and + * syslogger processes are disregarded since they are not connected to + * shared memory; we also disregard dead_end children here. Walsenders + * and archiver are also disregarded, they will be terminated later + * after writing the checkpoint record. + */ + if (CountChildren(BACKEND_TYPE_ALL - BACKEND_TYPE_WALSND) == 0 && + StartupPID == 0 && + WalReceiverPID == 0 && + BgWriterPID == 0 && + (CheckpointerPID == 0 || + (!FatalError && Shutdown < ImmediateShutdown)) && + WalWriterPID == 0 && + AutoVacPID == 0) + { + if (Shutdown >= ImmediateShutdown || FatalError) + { + /* + * Start waiting for dead_end children to die. This state + * change causes ServerLoop to stop creating new ones. + */ + pmState = PM_WAIT_DEAD_END; + + /* + * We already SIGQUIT'd the archiver and stats processes, if + * any, when we started immediate shutdown or entered + * FatalError state. + */ + } + else + { + /* + * If we get here, we are proceeding with normal shutdown. All + * the regular children are gone, and it's time to tell the + * checkpointer to do a shutdown checkpoint. + */ + Assert(Shutdown > NoShutdown); + /* Start the checkpointer if not running */ + if (CheckpointerPID == 0) + CheckpointerPID = StartCheckpointer(); + /* And tell it to shut down */ + if (CheckpointerPID != 0) + { + signal_child(CheckpointerPID, SIGUSR2); + pmState = PM_SHUTDOWN; + } + else + { + /* + * If we failed to fork a checkpointer, just shut down. + * Any required cleanup will happen at next restart. We + * set FatalError so that an "abnormal shutdown" message + * gets logged when we exit. + */ + FatalError = true; + pmState = PM_WAIT_DEAD_END; + + /* Kill the walsenders and archiver too */ + SignalChildren(SIGQUIT); + if (PgArchPID != 0) + signal_child(PgArchPID, SIGQUIT); + } + } + } + } + + if (pmState == PM_SHUTDOWN_2) + { + /* + * PM_SHUTDOWN_2 state ends when there's no other children than + * dead_end children left. There shouldn't be any regular backends + * left by now anyway; what we're really waiting for is walsenders and + * archiver. + */ + if (PgArchPID == 0 && CountChildren(BACKEND_TYPE_ALL) == 0) + { + pmState = PM_WAIT_DEAD_END; + } + } + + if (pmState == PM_WAIT_DEAD_END) + { + /* + * PM_WAIT_DEAD_END state ends when the BackendList is entirely empty + * (ie, no dead_end children remain), and the archiver is gone too. + * + * The reason we wait for those two is to protect them against a new + * postmaster starting conflicting subprocesses; this isn't an + * ironclad protection, but it at least helps in the + * shutdown-and-immediately-restart scenario. Note that they have + * already been sent appropriate shutdown signals, either during a + * normal state transition leading up to PM_WAIT_DEAD_END, or during + * FatalError processing. + */ + if (dlist_is_empty(&BackendList) && PgArchPID == 0) + { + /* These other guys should be dead already */ + Assert(StartupPID == 0); + Assert(WalReceiverPID == 0); + Assert(BgWriterPID == 0); + Assert(CheckpointerPID == 0); + Assert(WalWriterPID == 0); + Assert(AutoVacPID == 0); + /* syslogger is not considered here */ + pmState = PM_NO_CHILDREN; + } + } + + /* + * If we've been told to shut down, we exit as soon as there are no + * remaining children. If there was a crash, cleanup will occur at the + * next startup. (Before PostgreSQL 8.3, we tried to recover from the + * crash before exiting, but that seems unwise if we are quitting because + * we got SIGTERM from init --- there may well not be time for recovery + * before init decides to SIGKILL us.) + * + * Note that the syslogger continues to run. It will exit when it sees + * EOF on its input pipe, which happens when there are no more upstream + * processes. + */ + if (Shutdown > NoShutdown && pmState == PM_NO_CHILDREN) + { + if (FatalError) + { + ereport(LOG, (errmsg("abnormal database system shutdown"))); + ExitPostmaster(1); + } + else + { + /* + * Normal exit from the postmaster is here. We don't need to log + * anything here, since the UnlinkLockFiles proc_exit callback + * will do so, and that should be the last user-visible action. + */ + ExitPostmaster(0); + } + } + + /* + * If the startup process failed, or the user does not want an automatic + * restart after backend crashes, wait for all non-syslogger children to + * exit, and then exit postmaster. We don't try to reinitialize when the + * startup process fails, because more than likely it will just fail again + * and we will keep trying forever. + */ + if (pmState == PM_NO_CHILDREN) + { + if (StartupStatus == STARTUP_CRASHED) + { + ereport(LOG, + (errmsg("shutting down due to startup process failure"))); + ExitPostmaster(1); + } + if (!restart_after_crash) + { + ereport(LOG, + (errmsg("shutting down because restart_after_crash is off"))); + ExitPostmaster(1); + } + } + + /* + * If we need to recover from a crash, wait for all non-syslogger children + * to exit, then reset shmem and StartupDataBase. + */ + if (FatalError && pmState == PM_NO_CHILDREN) + { + ereport(LOG, + (errmsg("all server processes terminated; reinitializing"))); + + /* remove leftover temporary files after a crash */ + if (remove_temp_files_after_crash) + RemovePgTempFiles(); + + /* allow background workers to immediately restart */ + ResetBackgroundWorkerCrashTimes(); + + shmem_exit(1); + + /* re-read control file into local memory */ + LocalProcessControlFile(true); + + reset_shared(); + + StartupPID = StartupDataBase(); + Assert(StartupPID != 0); + StartupStatus = STARTUP_RUNNING; + pmState = PM_STARTUP; + /* crash recovery started, reset SIGKILL flag */ + AbortStartTime = 0; + } +} + + +/* + * Send a signal to a postmaster child process + * + * On systems that have setsid(), each child process sets itself up as a + * process group leader. For signals that are generally interpreted in the + * appropriate fashion, we signal the entire process group not just the + * direct child process. This allows us to, for example, SIGQUIT a blocked + * archive_recovery script, or SIGINT a script being run by a backend via + * system(). + * + * There is a race condition for recently-forked children: they might not + * have executed setsid() yet. So we signal the child directly as well as + * the group. We assume such a child will handle the signal before trying + * to spawn any grandchild processes. We also assume that signaling the + * child twice will not cause any problems. + */ +static void +signal_child(pid_t pid, int signal) +{ + if (kill(pid, signal) < 0) + elog(DEBUG3, "kill(%ld,%d) failed: %m", (long) pid, signal); +#ifdef HAVE_SETSID + switch (signal) + { + case SIGINT: + case SIGTERM: + case SIGQUIT: + case SIGSTOP: + case SIGKILL: + if (kill(-pid, signal) < 0) + elog(DEBUG3, "kill(%ld,%d) failed: %m", (long) (-pid), signal); + break; + default: + break; + } +#endif +} + +/* + * Send a signal to the targeted children (but NOT special children; + * dead_end children are never signaled, either). + */ +static bool +SignalSomeChildren(int signal, int target) +{ + dlist_iter iter; + bool signaled = false; + + dlist_foreach(iter, &BackendList) + { + Backend *bp = dlist_container(Backend, elem, iter.cur); + + if (bp->dead_end) + continue; + + /* + * Since target == BACKEND_TYPE_ALL is the most common case, we test + * it first and avoid touching shared memory for every child. + */ + if (target != BACKEND_TYPE_ALL) + { + /* + * Assign bkend_type for any recently announced WAL Sender + * processes. + */ + if (bp->bkend_type == BACKEND_TYPE_NORMAL && + IsPostmasterChildWalSender(bp->child_slot)) + bp->bkend_type = BACKEND_TYPE_WALSND; + + if (!(target & bp->bkend_type)) + continue; + } + + ereport(DEBUG4, + (errmsg_internal("sending signal %d to process %d", + signal, (int) bp->pid))); + signal_child(bp->pid, signal); + signaled = true; + } + return signaled; +} + +/* + * Send a termination signal to children. This considers all of our children + * processes, except syslogger and dead_end backends. + */ +static void +TerminateChildren(int signal) +{ + SignalChildren(signal); + if (StartupPID != 0) + { + signal_child(StartupPID, signal); + if (signal == SIGQUIT || signal == SIGKILL) + StartupStatus = STARTUP_SIGNALED; + } + if (BgWriterPID != 0) + signal_child(BgWriterPID, signal); + if (CheckpointerPID != 0) + signal_child(CheckpointerPID, signal); + if (WalWriterPID != 0) + signal_child(WalWriterPID, signal); + if (WalReceiverPID != 0) + signal_child(WalReceiverPID, signal); + if (AutoVacPID != 0) + signal_child(AutoVacPID, signal); + if (PgArchPID != 0) + signal_child(PgArchPID, signal); +} + +/* + * BackendStartup -- start backend process + * + * returns: STATUS_ERROR if the fork failed, STATUS_OK otherwise. + * + * Note: if you change this code, also consider StartAutovacuumWorker. + */ +static int +BackendStartup(Port *port) +{ + Backend *bn; /* for backend cleanup */ + pid_t pid; + + /* + * Create backend data structure. Better before the fork() so we can + * handle failure cleanly. + */ + bn = (Backend *) malloc(sizeof(Backend)); + if (!bn) + { + ereport(LOG, + (errcode(ERRCODE_OUT_OF_MEMORY), + errmsg("out of memory"))); + return STATUS_ERROR; + } + + /* + * Compute the cancel key that will be assigned to this backend. The + * backend will have its own copy in the forked-off process' value of + * MyCancelKey, so that it can transmit the key to the frontend. + */ + if (!RandomCancelKey(&MyCancelKey)) + { + free(bn); + ereport(LOG, + (errcode(ERRCODE_INTERNAL_ERROR), + errmsg("could not generate random cancel key"))); + return STATUS_ERROR; + } + + bn->cancel_key = MyCancelKey; + + /* Pass down canAcceptConnections state */ + port->canAcceptConnections = canAcceptConnections(BACKEND_TYPE_NORMAL); + bn->dead_end = (port->canAcceptConnections != CAC_OK); + + /* + * Unless it's a dead_end child, assign it a child slot number + */ + if (!bn->dead_end) + bn->child_slot = MyPMChildSlot = AssignPostmasterChildSlot(); + else + bn->child_slot = 0; + + /* Hasn't asked to be notified about any bgworkers yet */ + bn->bgworker_notify = false; + +#ifdef EXEC_BACKEND + pid = backend_forkexec(port); +#else /* !EXEC_BACKEND */ + pid = fork_process(); + if (pid == 0) /* child */ + { + free(bn); + + /* Detangle from postmaster */ + InitPostmasterChild(); + + /* Close the postmaster's sockets */ + ClosePostmasterPorts(false); + + /* Perform additional initialization and collect startup packet */ + BackendInitialize(port); + + /* + * Create a per-backend PGPROC struct in shared memory. We must do + * this before we can use LWLocks. In the !EXEC_BACKEND case (here) + * this could be delayed a bit further, but EXEC_BACKEND needs to do + * stuff with LWLocks before PostgresMain(), so we do it here as well + * for symmetry. + */ + InitProcess(); + + /* And run the backend */ + BackendRun(port); + } +#endif /* EXEC_BACKEND */ + + if (pid < 0) + { + /* in parent, fork failed */ + int save_errno = errno; + + if (!bn->dead_end) + (void) ReleasePostmasterChildSlot(bn->child_slot); + free(bn); + errno = save_errno; + ereport(LOG, + (errmsg("could not fork new process for connection: %m"))); + report_fork_failure_to_client(port, save_errno); + return STATUS_ERROR; + } + + /* in parent, successful fork */ + ereport(DEBUG2, + (errmsg_internal("forked new backend, pid=%d socket=%d", + (int) pid, (int) port->sock))); + + /* + * Everything's been successful, it's safe to add this backend to our list + * of backends. + */ + bn->pid = pid; + bn->bkend_type = BACKEND_TYPE_NORMAL; /* Can change later to WALSND */ + dlist_push_head(&BackendList, &bn->elem); + +#ifdef EXEC_BACKEND + if (!bn->dead_end) + ShmemBackendArrayAdd(bn); +#endif + + return STATUS_OK; +} + +/* + * Try to report backend fork() failure to client before we close the + * connection. Since we do not care to risk blocking the postmaster on + * this connection, we set the connection to non-blocking and try only once. + * + * This is grungy special-purpose code; we cannot use backend libpq since + * it's not up and running. + */ +static void +report_fork_failure_to_client(Port *port, int errnum) +{ + char buffer[1000]; + int rc; + + /* Format the error message packet (always V2 protocol) */ + snprintf(buffer, sizeof(buffer), "E%s%s\n", + _("could not fork new process for connection: "), + strerror(errnum)); + + /* Set port to non-blocking. Don't do send() if this fails */ + if (!pg_set_noblock(port->sock)) + return; + + /* We'll retry after EINTR, but ignore all other failures */ + do + { + rc = send(port->sock, buffer, strlen(buffer) + 1, 0); + } while (rc < 0 && errno == EINTR); +} + + +/* + * BackendInitialize -- initialize an interactive (postmaster-child) + * backend process, and collect the client's startup packet. + * + * returns: nothing. Will not return at all if there's any failure. + * + * Note: this code does not depend on having any access to shared memory. + * Indeed, our approach to SIGTERM/timeout handling *requires* that + * shared memory not have been touched yet; see comments within. + * In the EXEC_BACKEND case, we are physically attached to shared memory + * but have not yet set up most of our local pointers to shmem structures. + */ +static void +BackendInitialize(Port *port) +{ + int status; + int ret; + char remote_host[NI_MAXHOST]; + char remote_port[NI_MAXSERV]; + StringInfoData ps_data; + + /* Save port etc. for ps status */ + MyProcPort = port; + + /* Tell fd.c about the long-lived FD associated with the port */ + ReserveExternalFD(); + + /* + * PreAuthDelay is a debugging aid for investigating problems in the + * authentication cycle: it can be set in postgresql.conf to allow time to + * attach to the newly-forked backend with a debugger. (See also + * PostAuthDelay, which we allow clients to pass through PGOPTIONS, but it + * is not honored until after authentication.) + */ + if (PreAuthDelay > 0) + pg_usleep(PreAuthDelay * 1000000L); + + /* This flag will remain set until InitPostgres finishes authentication */ + ClientAuthInProgress = true; /* limit visibility of log messages */ + + /* set these to empty in case they are needed before we set them up */ + port->remote_host = ""; + port->remote_port = ""; + + /* + * Initialize libpq and enable reporting of ereport errors to the client. + * Must do this now because authentication uses libpq to send messages. + */ + pq_init(); /* initialize libpq to talk to client */ + whereToSendOutput = DestRemote; /* now safe to ereport to client */ + + /* + * We arrange to do _exit(1) if we receive SIGTERM or timeout while trying + * to collect the startup packet; while SIGQUIT results in _exit(2). + * Otherwise the postmaster cannot shutdown the database FAST or IMMED + * cleanly if a buggy client fails to send the packet promptly. + * + * Exiting with _exit(1) is only possible because we have not yet touched + * shared memory; therefore no outside-the-process state needs to get + * cleaned up. + */ + pqsignal(SIGTERM, process_startup_packet_die); + /* SIGQUIT handler was already set up by InitPostmasterChild */ + InitializeTimeouts(); /* establishes SIGALRM handler */ + PG_SETMASK(&StartupBlockSig); + + /* + * Get the remote host name and port for logging and status display. + */ + remote_host[0] = '\0'; + remote_port[0] = '\0'; + if ((ret = pg_getnameinfo_all(&port->raddr.addr, port->raddr.salen, + remote_host, sizeof(remote_host), + remote_port, sizeof(remote_port), + (log_hostname ? 0 : NI_NUMERICHOST) | NI_NUMERICSERV)) != 0) + ereport(WARNING, + (errmsg_internal("pg_getnameinfo_all() failed: %s", + gai_strerror(ret)))); + + /* + * Save remote_host and remote_port in port structure (after this, they + * will appear in log_line_prefix data for log messages). + */ + port->remote_host = strdup(remote_host); + port->remote_port = strdup(remote_port); + + /* And now we can issue the Log_connections message, if wanted */ + if (Log_connections) + { + if (remote_port[0]) + ereport(LOG, + (errmsg("connection received: host=%s port=%s", + remote_host, + remote_port))); + else + ereport(LOG, + (errmsg("connection received: host=%s", + remote_host))); + } + + /* + * If we did a reverse lookup to name, we might as well save the results + * rather than possibly repeating the lookup during authentication. + * + * Note that we don't want to specify NI_NAMEREQD above, because then we'd + * get nothing useful for a client without an rDNS entry. Therefore, we + * must check whether we got a numeric IPv4 or IPv6 address, and not save + * it into remote_hostname if so. (This test is conservative and might + * sometimes classify a hostname as numeric, but an error in that + * direction is safe; it only results in a possible extra lookup.) + */ + if (log_hostname && + ret == 0 && + strspn(remote_host, "0123456789.") < strlen(remote_host) && + strspn(remote_host, "0123456789ABCDEFabcdef:") < strlen(remote_host)) + port->remote_hostname = strdup(remote_host); + + /* + * Ready to begin client interaction. We will give up and _exit(1) after + * a time delay, so that a broken client can't hog a connection + * indefinitely. PreAuthDelay and any DNS interactions above don't count + * against the time limit. + * + * Note: AuthenticationTimeout is applied here while waiting for the + * startup packet, and then again in InitPostgres for the duration of any + * authentication operations. So a hostile client could tie up the + * process for nearly twice AuthenticationTimeout before we kick him off. + * + * Note: because PostgresMain will call InitializeTimeouts again, the + * registration of STARTUP_PACKET_TIMEOUT will be lost. This is okay + * since we never use it again after this function. + */ + RegisterTimeout(STARTUP_PACKET_TIMEOUT, StartupPacketTimeoutHandler); + enable_timeout_after(STARTUP_PACKET_TIMEOUT, AuthenticationTimeout * 1000); + + /* + * Receive the startup packet (which might turn out to be a cancel request + * packet). + */ + status = ProcessStartupPacket(port, false, false); + + /* + * Disable the timeout, and prevent SIGTERM again. + */ + disable_timeout(STARTUP_PACKET_TIMEOUT, false); + PG_SETMASK(&BlockSig); + + /* + * As a safety check that nothing in startup has yet performed + * shared-memory modifications that would need to be undone if we had + * exited through SIGTERM or timeout above, check that no on_shmem_exit + * handlers have been registered yet. (This isn't terribly bulletproof, + * since someone might misuse an on_proc_exit handler for shmem cleanup, + * but it's a cheap and helpful check. We cannot disallow on_proc_exit + * handlers unfortunately, since pq_init() already registered one.) + */ + check_on_shmem_exit_lists_are_empty(); + + /* + * Stop here if it was bad or a cancel packet. ProcessStartupPacket + * already did any appropriate error reporting. + */ + if (status != STATUS_OK) + proc_exit(0); + + /* + * Now that we have the user and database name, we can set the process + * title for ps. It's good to do this as early as possible in startup. + */ + initStringInfo(&ps_data); + if (am_walsender) + appendStringInfo(&ps_data, "%s ", GetBackendTypeDesc(B_WAL_SENDER)); + appendStringInfo(&ps_data, "%s ", port->user_name); + if (!am_walsender) + appendStringInfo(&ps_data, "%s ", port->database_name); + appendStringInfo(&ps_data, "%s", port->remote_host); + if (port->remote_port[0] != '\0') + appendStringInfo(&ps_data, "(%s)", port->remote_port); + + init_ps_display(ps_data.data); + pfree(ps_data.data); + + set_ps_display("initializing"); +} + + +/* + * BackendRun -- set up the backend's argument list and invoke PostgresMain() + * + * returns: + * Doesn't return at all. + */ +static void +BackendRun(Port *port) +{ + /* + * Make sure we aren't in PostmasterContext anymore. (We can't delete it + * just yet, though, because InitPostgres will need the HBA data.) + */ + MemoryContextSwitchTo(TopMemoryContext); + + PostgresMain(port->database_name, port->user_name); +} + + +#ifdef EXEC_BACKEND + +/* + * postmaster_forkexec -- fork and exec a postmaster subprocess + * + * The caller must have set up the argv array already, except for argv[2] + * which will be filled with the name of the temp variable file. + * + * Returns the child process PID, or -1 on fork failure (a suitable error + * message has been logged on failure). + * + * All uses of this routine will dispatch to SubPostmasterMain in the + * child process. + */ +pid_t +postmaster_forkexec(int argc, char *argv[]) +{ + Port port; + + /* This entry point passes dummy values for the Port variables */ + memset(&port, 0, sizeof(port)); + return internal_forkexec(argc, argv, &port); +} + +/* + * backend_forkexec -- fork/exec off a backend process + * + * Some operating systems (WIN32) don't have fork() so we have to simulate + * it by storing parameters that need to be passed to the child and + * then create a new child process. + * + * returns the pid of the fork/exec'd process, or -1 on failure + */ +static pid_t +backend_forkexec(Port *port) +{ + char *av[4]; + int ac = 0; + + av[ac++] = "postgres"; + av[ac++] = "--forkbackend"; + av[ac++] = NULL; /* filled in by internal_forkexec */ + + av[ac] = NULL; + Assert(ac < lengthof(av)); + + return internal_forkexec(ac, av, port); +} + +#ifndef WIN32 + +/* + * internal_forkexec non-win32 implementation + * + * - writes out backend variables to the parameter file + * - fork():s, and then exec():s the child process + */ +static pid_t +internal_forkexec(int argc, char *argv[], Port *port) +{ + static unsigned long tmpBackendFileNum = 0; + pid_t pid; + char tmpfilename[MAXPGPATH]; + BackendParameters param; + FILE *fp; + + if (!save_backend_variables(¶m, port)) + return -1; /* log made by save_backend_variables */ + + /* Calculate name for temp file */ + snprintf(tmpfilename, MAXPGPATH, "%s/%s.backend_var.%d.%lu", + PG_TEMP_FILES_DIR, PG_TEMP_FILE_PREFIX, + MyProcPid, ++tmpBackendFileNum); + + /* Open file */ + fp = AllocateFile(tmpfilename, PG_BINARY_W); + if (!fp) + { + /* + * As in OpenTemporaryFileInTablespace, try to make the temp-file + * directory, ignoring errors. + */ + (void) MakePGDirectory(PG_TEMP_FILES_DIR); + + fp = AllocateFile(tmpfilename, PG_BINARY_W); + if (!fp) + { + ereport(LOG, + (errcode_for_file_access(), + errmsg("could not create file \"%s\": %m", + tmpfilename))); + return -1; + } + } + + if (fwrite(¶m, sizeof(param), 1, fp) != 1) + { + ereport(LOG, + (errcode_for_file_access(), + errmsg("could not write to file \"%s\": %m", tmpfilename))); + FreeFile(fp); + return -1; + } + + /* Release file */ + if (FreeFile(fp)) + { + ereport(LOG, + (errcode_for_file_access(), + errmsg("could not write to file \"%s\": %m", tmpfilename))); + return -1; + } + + /* Make sure caller set up argv properly */ + Assert(argc >= 3); + Assert(argv[argc] == NULL); + Assert(strncmp(argv[1], "--fork", 6) == 0); + Assert(argv[2] == NULL); + + /* Insert temp file name after --fork argument */ + argv[2] = tmpfilename; + + /* Fire off execv in child */ + if ((pid = fork_process()) == 0) + { + if (execv(postgres_exec_path, argv) < 0) + { + ereport(LOG, + (errmsg("could not execute server process \"%s\": %m", + postgres_exec_path))); + /* We're already in the child process here, can't return */ + exit(1); + } + } + + return pid; /* Parent returns pid, or -1 on fork failure */ +} +#else /* WIN32 */ + +/* + * internal_forkexec win32 implementation + * + * - starts backend using CreateProcess(), in suspended state + * - writes out backend variables to the parameter file + * - during this, duplicates handles and sockets required for + * inheritance into the new process + * - resumes execution of the new process once the backend parameter + * file is complete. + */ +static pid_t +internal_forkexec(int argc, char *argv[], Port *port) +{ + int retry_count = 0; + STARTUPINFO si; + PROCESS_INFORMATION pi; + int i; + int j; + char cmdLine[MAXPGPATH * 2]; + HANDLE paramHandle; + BackendParameters *param; + SECURITY_ATTRIBUTES sa; + char paramHandleStr[32]; + win32_deadchild_waitinfo *childinfo; + + /* Make sure caller set up argv properly */ + Assert(argc >= 3); + Assert(argv[argc] == NULL); + Assert(strncmp(argv[1], "--fork", 6) == 0); + Assert(argv[2] == NULL); + + /* Resume here if we need to retry */ +retry: + + /* Set up shared memory for parameter passing */ + ZeroMemory(&sa, sizeof(sa)); + sa.nLength = sizeof(sa); + sa.bInheritHandle = TRUE; + paramHandle = CreateFileMapping(INVALID_HANDLE_VALUE, + &sa, + PAGE_READWRITE, + 0, + sizeof(BackendParameters), + NULL); + if (paramHandle == INVALID_HANDLE_VALUE) + { + ereport(LOG, + (errmsg("could not create backend parameter file mapping: error code %lu", + GetLastError()))); + return -1; + } + + param = MapViewOfFile(paramHandle, FILE_MAP_WRITE, 0, 0, sizeof(BackendParameters)); + if (!param) + { + ereport(LOG, + (errmsg("could not map backend parameter memory: error code %lu", + GetLastError()))); + CloseHandle(paramHandle); + return -1; + } + + /* Insert temp file name after --fork argument */ +#ifdef _WIN64 + sprintf(paramHandleStr, "%llu", (LONG_PTR) paramHandle); +#else + sprintf(paramHandleStr, "%lu", (DWORD) paramHandle); +#endif + argv[2] = paramHandleStr; + + /* Format the cmd line */ + cmdLine[sizeof(cmdLine) - 1] = '\0'; + cmdLine[sizeof(cmdLine) - 2] = '\0'; + snprintf(cmdLine, sizeof(cmdLine) - 1, "\"%s\"", postgres_exec_path); + i = 0; + while (argv[++i] != NULL) + { + j = strlen(cmdLine); + snprintf(cmdLine + j, sizeof(cmdLine) - 1 - j, " \"%s\"", argv[i]); + } + if (cmdLine[sizeof(cmdLine) - 2] != '\0') + { + ereport(LOG, + (errmsg("subprocess command line too long"))); + UnmapViewOfFile(param); + CloseHandle(paramHandle); + return -1; + } + + memset(&pi, 0, sizeof(pi)); + memset(&si, 0, sizeof(si)); + si.cb = sizeof(si); + + /* + * Create the subprocess in a suspended state. This will be resumed later, + * once we have written out the parameter file. + */ + if (!CreateProcess(NULL, cmdLine, NULL, NULL, TRUE, CREATE_SUSPENDED, + NULL, NULL, &si, &pi)) + { + ereport(LOG, + (errmsg("CreateProcess() call failed: %m (error code %lu)", + GetLastError()))); + UnmapViewOfFile(param); + CloseHandle(paramHandle); + return -1; + } + + if (!save_backend_variables(param, port, pi.hProcess, pi.dwProcessId)) + { + /* + * log made by save_backend_variables, but we have to clean up the + * mess with the half-started process + */ + if (!TerminateProcess(pi.hProcess, 255)) + ereport(LOG, + (errmsg_internal("could not terminate unstarted process: error code %lu", + GetLastError()))); + CloseHandle(pi.hProcess); + CloseHandle(pi.hThread); + UnmapViewOfFile(param); + CloseHandle(paramHandle); + return -1; /* log made by save_backend_variables */ + } + + /* Drop the parameter shared memory that is now inherited to the backend */ + if (!UnmapViewOfFile(param)) + ereport(LOG, + (errmsg("could not unmap view of backend parameter file: error code %lu", + GetLastError()))); + if (!CloseHandle(paramHandle)) + ereport(LOG, + (errmsg("could not close handle to backend parameter file: error code %lu", + GetLastError()))); + + /* + * Reserve the memory region used by our main shared memory segment before + * we resume the child process. Normally this should succeed, but if ASLR + * is active then it might sometimes fail due to the stack or heap having + * gotten mapped into that range. In that case, just terminate the + * process and retry. + */ + if (!pgwin32_ReserveSharedMemoryRegion(pi.hProcess)) + { + /* pgwin32_ReserveSharedMemoryRegion already made a log entry */ + if (!TerminateProcess(pi.hProcess, 255)) + ereport(LOG, + (errmsg_internal("could not terminate process that failed to reserve memory: error code %lu", + GetLastError()))); + CloseHandle(pi.hProcess); + CloseHandle(pi.hThread); + if (++retry_count < 100) + goto retry; + ereport(LOG, + (errmsg("giving up after too many tries to reserve shared memory"), + errhint("This might be caused by ASLR or antivirus software."))); + return -1; + } + + /* + * Now that the backend variables are written out, we start the child + * thread so it can start initializing while we set up the rest of the + * parent state. + */ + if (ResumeThread(pi.hThread) == -1) + { + if (!TerminateProcess(pi.hProcess, 255)) + { + ereport(LOG, + (errmsg_internal("could not terminate unstartable process: error code %lu", + GetLastError()))); + CloseHandle(pi.hProcess); + CloseHandle(pi.hThread); + return -1; + } + CloseHandle(pi.hProcess); + CloseHandle(pi.hThread); + ereport(LOG, + (errmsg_internal("could not resume thread of unstarted process: error code %lu", + GetLastError()))); + return -1; + } + + /* + * Queue a waiter to signal when this child dies. The wait will be handled + * automatically by an operating system thread pool. The memory will be + * freed by a later call to waitpid(). + */ + childinfo = palloc(sizeof(win32_deadchild_waitinfo)); + childinfo->procHandle = pi.hProcess; + childinfo->procId = pi.dwProcessId; + + if (!RegisterWaitForSingleObject(&childinfo->waitHandle, + pi.hProcess, + pgwin32_deadchild_callback, + childinfo, + INFINITE, + WT_EXECUTEONLYONCE | WT_EXECUTEINWAITTHREAD)) + ereport(FATAL, + (errmsg_internal("could not register process for wait: error code %lu", + GetLastError()))); + + /* Don't close pi.hProcess here - waitpid() needs access to it */ + + CloseHandle(pi.hThread); + + return pi.dwProcessId; +} +#endif /* WIN32 */ + + +/* + * SubPostmasterMain -- Get the fork/exec'd process into a state equivalent + * to what it would be if we'd simply forked on Unix, and then + * dispatch to the appropriate place. + * + * The first two command line arguments are expected to be "--forkFOO" + * (where FOO indicates which postmaster child we are to become), and + * the name of a variables file that we can read to load data that would + * have been inherited by fork() on Unix. Remaining arguments go to the + * subprocess FooMain() routine. + */ +void +SubPostmasterMain(int argc, char *argv[]) +{ + Port port; + + /* In EXEC_BACKEND case we will not have inherited these settings */ + IsPostmasterEnvironment = true; + whereToSendOutput = DestNone; + + /* Setup essential subsystems (to ensure elog() behaves sanely) */ + InitializeGUCOptions(); + + /* Check we got appropriate args */ + if (argc < 3) + elog(FATAL, "invalid subpostmaster invocation"); + + /* Read in the variables file */ + memset(&port, 0, sizeof(Port)); + read_backend_variables(argv[2], &port); + + /* Close the postmaster's sockets (as soon as we know them) */ + ClosePostmasterPorts(strcmp(argv[1], "--forklog") == 0); + + /* Setup as postmaster child */ + InitPostmasterChild(); + + /* + * If appropriate, physically re-attach to shared memory segment. We want + * to do this before going any further to ensure that we can attach at the + * same address the postmaster used. On the other hand, if we choose not + * to re-attach, we may have other cleanup to do. + * + * If testing EXEC_BACKEND on Linux, you should run this as root before + * starting the postmaster: + * + * sysctl -w kernel.randomize_va_space=0 + * + * This prevents using randomized stack and code addresses that cause the + * child process's memory map to be different from the parent's, making it + * sometimes impossible to attach to shared memory at the desired address. + * Return the setting to its old value (usually '1' or '2') when finished. + */ + if (strcmp(argv[1], "--forkbackend") == 0 || + strcmp(argv[1], "--forkavlauncher") == 0 || + strcmp(argv[1], "--forkavworker") == 0 || + strcmp(argv[1], "--forkaux") == 0 || + strncmp(argv[1], "--forkbgworker=", 15) == 0) + PGSharedMemoryReAttach(); + else + PGSharedMemoryNoReAttach(); + + /* autovacuum needs this set before calling InitProcess */ + if (strcmp(argv[1], "--forkavlauncher") == 0) + AutovacuumLauncherIAm(); + if (strcmp(argv[1], "--forkavworker") == 0) + AutovacuumWorkerIAm(); + + /* Read in remaining GUC variables */ + read_nondefault_variables(); + + /* + * Check that the data directory looks valid, which will also check the + * privileges on the data directory and update our umask and file/group + * variables for creating files later. Note: this should really be done + * before we create any files or directories. + */ + checkDataDir(); + + /* + * (re-)read control file, as it contains config. The postmaster will + * already have read this, but this process doesn't know about that. + */ + LocalProcessControlFile(false); + + /* + * Reload any libraries that were preloaded by the postmaster. Since we + * exec'd this process, those libraries didn't come along with us; but we + * should load them into all child processes to be consistent with the + * non-EXEC_BACKEND behavior. + */ + process_shared_preload_libraries(); + + /* Run backend or appropriate child */ + if (strcmp(argv[1], "--forkbackend") == 0) + { + Assert(argc == 3); /* shouldn't be any more args */ + + /* + * Need to reinitialize the SSL library in the backend, since the + * context structures contain function pointers and cannot be passed + * through the parameter file. + * + * If for some reason reload fails (maybe the user installed broken + * key files), soldier on without SSL; that's better than all + * connections becoming impossible. + * + * XXX should we do this in all child processes? For the moment it's + * enough to do it in backend children. + */ +#ifdef USE_SSL + if (EnableSSL) + { + if (secure_initialize(false) == 0) + LoadedSSL = true; + else + ereport(LOG, + (errmsg("SSL configuration could not be loaded in child process"))); + } +#endif + + /* + * Perform additional initialization and collect startup packet. + * + * We want to do this before InitProcess() for a couple of reasons: 1. + * so that we aren't eating up a PGPROC slot while waiting on the + * client. 2. so that if InitProcess() fails due to being out of + * PGPROC slots, we have already initialized libpq and are able to + * report the error to the client. + */ + BackendInitialize(&port); + + /* Restore basic shared memory pointers */ + InitShmemAccess(UsedShmemSegAddr); + + /* Need a PGPROC to run CreateSharedMemoryAndSemaphores */ + InitProcess(); + + /* Attach process to shared data structures */ + CreateSharedMemoryAndSemaphores(); + + /* And run the backend */ + BackendRun(&port); /* does not return */ + } + if (strcmp(argv[1], "--forkaux") == 0) + { + AuxProcType auxtype; + + Assert(argc == 4); + + /* Restore basic shared memory pointers */ + InitShmemAccess(UsedShmemSegAddr); + + /* Need a PGPROC to run CreateSharedMemoryAndSemaphores */ + InitAuxiliaryProcess(); + + /* Attach process to shared data structures */ + CreateSharedMemoryAndSemaphores(); + + auxtype = atoi(argv[3]); + AuxiliaryProcessMain(auxtype); /* does not return */ + } + if (strcmp(argv[1], "--forkavlauncher") == 0) + { + /* Restore basic shared memory pointers */ + InitShmemAccess(UsedShmemSegAddr); + + /* Need a PGPROC to run CreateSharedMemoryAndSemaphores */ + InitProcess(); + + /* Attach process to shared data structures */ + CreateSharedMemoryAndSemaphores(); + + AutoVacLauncherMain(argc - 2, argv + 2); /* does not return */ + } + if (strcmp(argv[1], "--forkavworker") == 0) + { + /* Restore basic shared memory pointers */ + InitShmemAccess(UsedShmemSegAddr); + + /* Need a PGPROC to run CreateSharedMemoryAndSemaphores */ + InitProcess(); + + /* Attach process to shared data structures */ + CreateSharedMemoryAndSemaphores(); + + AutoVacWorkerMain(argc - 2, argv + 2); /* does not return */ + } + if (strncmp(argv[1], "--forkbgworker=", 15) == 0) + { + int shmem_slot; + + /* do this as early as possible; in particular, before InitProcess() */ + IsBackgroundWorker = true; + + /* Restore basic shared memory pointers */ + InitShmemAccess(UsedShmemSegAddr); + + /* Need a PGPROC to run CreateSharedMemoryAndSemaphores */ + InitProcess(); + + /* Attach process to shared data structures */ + CreateSharedMemoryAndSemaphores(); + + /* Fetch MyBgworkerEntry from shared memory */ + shmem_slot = atoi(argv[1] + 15); + MyBgworkerEntry = BackgroundWorkerEntry(shmem_slot); + + StartBackgroundWorker(); + } + if (strcmp(argv[1], "--forklog") == 0) + { + /* Do not want to attach to shared memory */ + + SysLoggerMain(argc, argv); /* does not return */ + } + + abort(); /* shouldn't get here */ +} +#endif /* EXEC_BACKEND */ + + +/* + * ExitPostmaster -- cleanup + * + * Do NOT call exit() directly --- always go through here! + */ +static void +ExitPostmaster(int status) +{ +#ifdef HAVE_PTHREAD_IS_THREADED_NP + + /* + * There is no known cause for a postmaster to become multithreaded after + * startup. Recheck to account for the possibility of unknown causes. + * This message uses LOG level, because an unclean shutdown at this point + * would usually not look much different from a clean shutdown. + */ + if (pthread_is_threaded_np() != 0) + ereport(LOG, + (errcode(ERRCODE_INTERNAL_ERROR), + errmsg_internal("postmaster became multithreaded"), + errdetail("Please report this to <%s>.", PACKAGE_BUGREPORT))); +#endif + + /* should cleanup shared memory and kill all backends */ + + /* + * Not sure of the semantics here. When the Postmaster dies, should the + * backends all be killed? probably not. + * + * MUST -- vadim 05-10-1999 + */ + + proc_exit(status); +} + +/* + * sigusr1_handler - handle signal conditions from child processes + */ +static void +sigusr1_handler(SIGNAL_ARGS) +{ + int save_errno = errno; + + /* + * We rely on the signal mechanism to have blocked all signals ... except + * on Windows, which lacks sigaction(), so we have to do it manually. + */ +#ifdef WIN32 + PG_SETMASK(&BlockSig); +#endif + + /* + * RECOVERY_STARTED and BEGIN_HOT_STANDBY signals are ignored in + * unexpected states. If the startup process quickly starts up, completes + * recovery, exits, we might process the death of the startup process + * first. We don't want to go back to recovery in that case. + */ + if (CheckPostmasterSignal(PMSIGNAL_RECOVERY_STARTED) && + pmState == PM_STARTUP && Shutdown == NoShutdown) + { + /* WAL redo has started. We're out of reinitialization. */ + FatalError = false; + AbortStartTime = 0; + + /* + * Start the archiver if we're responsible for (re-)archiving received + * files. + */ + Assert(PgArchPID == 0); + if (XLogArchivingAlways()) + PgArchPID = StartArchiver(); + + /* + * If we aren't planning to enter hot standby mode later, treat + * RECOVERY_STARTED as meaning we're out of startup, and report status + * accordingly. + */ + if (!EnableHotStandby) + { + AddToDataDirLockFile(LOCK_FILE_LINE_PM_STATUS, PM_STATUS_STANDBY); +#ifdef USE_SYSTEMD + sd_notify(0, "READY=1"); +#endif + } + + pmState = PM_RECOVERY; + } + + if (CheckPostmasterSignal(PMSIGNAL_BEGIN_HOT_STANDBY) && + pmState == PM_RECOVERY && Shutdown == NoShutdown) + { + ereport(LOG, + (errmsg("database system is ready to accept read-only connections"))); + + /* Report status */ + AddToDataDirLockFile(LOCK_FILE_LINE_PM_STATUS, PM_STATUS_READY); +#ifdef USE_SYSTEMD + sd_notify(0, "READY=1"); +#endif + + pmState = PM_HOT_STANDBY; + connsAllowed = true; + + /* Some workers may be scheduled to start now */ + StartWorkerNeeded = true; + } + + /* Process background worker state changes. */ + if (CheckPostmasterSignal(PMSIGNAL_BACKGROUND_WORKER_CHANGE)) + { + /* Accept new worker requests only if not stopping. */ + BackgroundWorkerStateChange(pmState < PM_STOP_BACKENDS); + StartWorkerNeeded = true; + } + + if (StartWorkerNeeded || HaveCrashedWorker) + maybe_start_bgworkers(); + + /* Tell syslogger to rotate logfile if requested */ + if (SysLoggerPID != 0) + { + if (CheckLogrotateSignal()) + { + signal_child(SysLoggerPID, SIGUSR1); + RemoveLogrotateSignalFiles(); + } + else if (CheckPostmasterSignal(PMSIGNAL_ROTATE_LOGFILE)) + { + signal_child(SysLoggerPID, SIGUSR1); + } + } + + if (CheckPostmasterSignal(PMSIGNAL_START_AUTOVAC_LAUNCHER) && + Shutdown <= SmartShutdown && pmState < PM_STOP_BACKENDS) + { + /* + * Start one iteration of the autovacuum daemon, even if autovacuuming + * is nominally not enabled. This is so we can have an active defense + * against transaction ID wraparound. We set a flag for the main loop + * to do it rather than trying to do it here --- this is because the + * autovac process itself may send the signal, and we want to handle + * that by launching another iteration as soon as the current one + * completes. + */ + start_autovac_launcher = true; + } + + if (CheckPostmasterSignal(PMSIGNAL_START_AUTOVAC_WORKER) && + Shutdown <= SmartShutdown && pmState < PM_STOP_BACKENDS) + { + /* The autovacuum launcher wants us to start a worker process. */ + StartAutovacuumWorker(); + } + + if (CheckPostmasterSignal(PMSIGNAL_START_WALRECEIVER)) + { + /* Startup Process wants us to start the walreceiver process. */ + /* Start immediately if possible, else remember request for later. */ + WalReceiverRequested = true; + MaybeStartWalReceiver(); + } + + /* + * Try to advance postmaster's state machine, if a child requests it. + * + * Be careful about the order of this action relative to sigusr1_handler's + * other actions. Generally, this should be after other actions, in case + * they have effects PostmasterStateMachine would need to know about. + * However, we should do it before the CheckPromoteSignal step, which + * cannot have any (immediate) effect on the state machine, but does + * depend on what state we're in now. + */ + if (CheckPostmasterSignal(PMSIGNAL_ADVANCE_STATE_MACHINE)) + { + PostmasterStateMachine(); + } + + if (StartupPID != 0 && + (pmState == PM_STARTUP || pmState == PM_RECOVERY || + pmState == PM_HOT_STANDBY) && + CheckPromoteSignal()) + { + /* + * Tell startup process to finish recovery. + * + * Leave the promote signal file in place and let the Startup process + * do the unlink. + */ + signal_child(StartupPID, SIGUSR2); + } + +#ifdef WIN32 + PG_SETMASK(&UnBlockSig); +#endif + + errno = save_errno; +} + +/* + * SIGTERM while processing startup packet. + * + * Running proc_exit() from a signal handler would be quite unsafe. + * However, since we have not yet touched shared memory, we can just + * pull the plug and exit without running any atexit handlers. + * + * One might be tempted to try to send a message, or log one, indicating + * why we are disconnecting. However, that would be quite unsafe in itself. + * Also, it seems undesirable to provide clues about the database's state + * to a client that has not yet completed authentication, or even sent us + * a startup packet. + */ +static void +process_startup_packet_die(SIGNAL_ARGS) +{ + _exit(1); +} + +/* + * Dummy signal handler + * + * We use this for signals that we don't actually use in the postmaster, + * but we do use in backends. If we were to SIG_IGN such signals in the + * postmaster, then a newly started backend might drop a signal that arrives + * before it's able to reconfigure its signal processing. (See notes in + * tcop/postgres.c.) + */ +static void +dummy_handler(SIGNAL_ARGS) +{ +} + +/* + * Timeout while processing startup packet. + * As for process_startup_packet_die(), we exit via _exit(1). + */ +static void +StartupPacketTimeoutHandler(void) +{ + _exit(1); +} + + +/* + * Generate a random cancel key. + */ +static bool +RandomCancelKey(int32 *cancel_key) +{ + return pg_strong_random(cancel_key, sizeof(int32)); +} + +/* + * Count up number of child processes of specified types (dead_end children + * are always excluded). + */ +static int +CountChildren(int target) +{ + dlist_iter iter; + int cnt = 0; + + dlist_foreach(iter, &BackendList) + { + Backend *bp = dlist_container(Backend, elem, iter.cur); + + if (bp->dead_end) + continue; + + /* + * Since target == BACKEND_TYPE_ALL is the most common case, we test + * it first and avoid touching shared memory for every child. + */ + if (target != BACKEND_TYPE_ALL) + { + /* + * Assign bkend_type for any recently announced WAL Sender + * processes. + */ + if (bp->bkend_type == BACKEND_TYPE_NORMAL && + IsPostmasterChildWalSender(bp->child_slot)) + bp->bkend_type = BACKEND_TYPE_WALSND; + + if (!(target & bp->bkend_type)) + continue; + } + + cnt++; + } + return cnt; +} + + +/* + * StartChildProcess -- start an auxiliary process for the postmaster + * + * "type" determines what kind of child will be started. All child types + * initially go to AuxiliaryProcessMain, which will handle common setup. + * + * Return value of StartChildProcess is subprocess' PID, or 0 if failed + * to start subprocess. + */ +static pid_t +StartChildProcess(AuxProcType type) +{ + pid_t pid; + +#ifdef EXEC_BACKEND + { + char *av[10]; + int ac = 0; + char typebuf[32]; + + /* + * Set up command-line arguments for subprocess + */ + av[ac++] = "postgres"; + av[ac++] = "--forkaux"; + av[ac++] = NULL; /* filled in by postmaster_forkexec */ + + snprintf(typebuf, sizeof(typebuf), "%d", type); + av[ac++] = typebuf; + + av[ac] = NULL; + Assert(ac < lengthof(av)); + + pid = postmaster_forkexec(ac, av); + } +#else /* !EXEC_BACKEND */ + pid = fork_process(); + + if (pid == 0) /* child */ + { + InitPostmasterChild(); + + /* Close the postmaster's sockets */ + ClosePostmasterPorts(false); + + /* Release postmaster's working memory context */ + MemoryContextSwitchTo(TopMemoryContext); + MemoryContextDelete(PostmasterContext); + PostmasterContext = NULL; + + AuxiliaryProcessMain(type); /* does not return */ + } +#endif /* EXEC_BACKEND */ + + if (pid < 0) + { + /* in parent, fork failed */ + int save_errno = errno; + + errno = save_errno; + switch (type) + { + case StartupProcess: + ereport(LOG, + (errmsg("could not fork startup process: %m"))); + break; + case ArchiverProcess: + ereport(LOG, + (errmsg("could not fork archiver process: %m"))); + break; + case BgWriterProcess: + ereport(LOG, + (errmsg("could not fork background writer process: %m"))); + break; + case CheckpointerProcess: + ereport(LOG, + (errmsg("could not fork checkpointer process: %m"))); + break; + case WalWriterProcess: + ereport(LOG, + (errmsg("could not fork WAL writer process: %m"))); + break; + case WalReceiverProcess: + ereport(LOG, + (errmsg("could not fork WAL receiver process: %m"))); + break; + default: + ereport(LOG, + (errmsg("could not fork process: %m"))); + break; + } + + /* + * fork failure is fatal during startup, but there's no need to choke + * immediately if starting other child types fails. + */ + if (type == StartupProcess) + ExitPostmaster(1); + return 0; + } + + /* + * in parent, successful fork + */ + return pid; +} + +/* + * StartAutovacuumWorker + * Start an autovac worker process. + * + * This function is here because it enters the resulting PID into the + * postmaster's private backends list. + * + * NB -- this code very roughly matches BackendStartup. + */ +static void +StartAutovacuumWorker(void) +{ + Backend *bn; + + /* + * If not in condition to run a process, don't try, but handle it like a + * fork failure. This does not normally happen, since the signal is only + * supposed to be sent by autovacuum launcher when it's OK to do it, but + * we have to check to avoid race-condition problems during DB state + * changes. + */ + if (canAcceptConnections(BACKEND_TYPE_AUTOVAC) == CAC_OK) + { + /* + * Compute the cancel key that will be assigned to this session. We + * probably don't need cancel keys for autovac workers, but we'd + * better have something random in the field to prevent unfriendly + * people from sending cancels to them. + */ + if (!RandomCancelKey(&MyCancelKey)) + { + ereport(LOG, + (errcode(ERRCODE_INTERNAL_ERROR), + errmsg("could not generate random cancel key"))); + return; + } + + bn = (Backend *) malloc(sizeof(Backend)); + if (bn) + { + bn->cancel_key = MyCancelKey; + + /* Autovac workers are not dead_end and need a child slot */ + bn->dead_end = false; + bn->child_slot = MyPMChildSlot = AssignPostmasterChildSlot(); + bn->bgworker_notify = false; + + bn->pid = StartAutoVacWorker(); + if (bn->pid > 0) + { + bn->bkend_type = BACKEND_TYPE_AUTOVAC; + dlist_push_head(&BackendList, &bn->elem); +#ifdef EXEC_BACKEND + ShmemBackendArrayAdd(bn); +#endif + /* all OK */ + return; + } + + /* + * fork failed, fall through to report -- actual error message was + * logged by StartAutoVacWorker + */ + (void) ReleasePostmasterChildSlot(bn->child_slot); + free(bn); + } + else + ereport(LOG, + (errcode(ERRCODE_OUT_OF_MEMORY), + errmsg("out of memory"))); + } + + /* + * Report the failure to the launcher, if it's running. (If it's not, we + * might not even be connected to shared memory, so don't try to call + * AutoVacWorkerFailed.) Note that we also need to signal it so that it + * responds to the condition, but we don't do that here, instead waiting + * for ServerLoop to do it. This way we avoid a ping-pong signaling in + * quick succession between the autovac launcher and postmaster in case + * things get ugly. + */ + if (AutoVacPID != 0) + { + AutoVacWorkerFailed(); + avlauncher_needs_signal = true; + } +} + +/* + * MaybeStartWalReceiver + * Start the WAL receiver process, if not running and our state allows. + * + * Note: if WalReceiverPID is already nonzero, it might seem that we should + * clear WalReceiverRequested. However, there's a race condition if the + * walreceiver terminates and the startup process immediately requests a new + * one: it's quite possible to get the signal for the request before reaping + * the dead walreceiver process. Better to risk launching an extra + * walreceiver than to miss launching one we need. (The walreceiver code + * has logic to recognize that it should go away if not needed.) + */ +static void +MaybeStartWalReceiver(void) +{ + if (WalReceiverPID == 0 && + (pmState == PM_STARTUP || pmState == PM_RECOVERY || + pmState == PM_HOT_STANDBY) && + Shutdown <= SmartShutdown) + { + WalReceiverPID = StartWalReceiver(); + if (WalReceiverPID != 0) + WalReceiverRequested = false; + /* else leave the flag set, so we'll try again later */ + } +} + + +/* + * Create the opts file + */ +static bool +CreateOptsFile(int argc, char *argv[], char *fullprogname) +{ + FILE *fp; + int i; + +#define OPTS_FILE "postmaster.opts" + + if ((fp = fopen(OPTS_FILE, "w")) == NULL) + { + ereport(LOG, + (errcode_for_file_access(), + errmsg("could not create file \"%s\": %m", OPTS_FILE))); + return false; + } + + fprintf(fp, "%s", fullprogname); + for (i = 1; i < argc; i++) + fprintf(fp, " \"%s\"", argv[i]); + fputs("\n", fp); + + if (fclose(fp)) + { + ereport(LOG, + (errcode_for_file_access(), + errmsg("could not write file \"%s\": %m", OPTS_FILE))); + return false; + } + + return true; +} + + +/* + * MaxLivePostmasterChildren + * + * This reports the number of entries needed in per-child-process arrays + * (the PMChildFlags array, and if EXEC_BACKEND the ShmemBackendArray). + * These arrays include regular backends, autovac workers, walsenders + * and background workers, but not special children nor dead_end children. + * This allows the arrays to have a fixed maximum size, to wit the same + * too-many-children limit enforced by canAcceptConnections(). The exact value + * isn't too critical as long as it's more than MaxBackends. + */ +int +MaxLivePostmasterChildren(void) +{ + return 2 * (MaxConnections + autovacuum_max_workers + 1 + + max_wal_senders + max_worker_processes); +} + +/* + * Connect background worker to a database. + */ +void +BackgroundWorkerInitializeConnection(const char *dbname, const char *username, uint32 flags) +{ + BackgroundWorker *worker = MyBgworkerEntry; + + /* XXX is this the right errcode? */ + if (!(worker->bgw_flags & BGWORKER_BACKEND_DATABASE_CONNECTION)) + ereport(FATAL, + (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED), + errmsg("database connection requirement not indicated during registration"))); + + InitPostgres(dbname, InvalidOid, /* database to connect to */ + username, InvalidOid, /* role to connect as */ + false, /* never honor session_preload_libraries */ + (flags & BGWORKER_BYPASS_ALLOWCONN) != 0, /* ignore datallowconn? */ + NULL); /* no out_dbname */ + + /* it had better not gotten out of "init" mode yet */ + if (!IsInitProcessingMode()) + ereport(ERROR, + (errmsg("invalid processing mode in background worker"))); + SetProcessingMode(NormalProcessing); +} + +/* + * Connect background worker to a database using OIDs. + */ +void +BackgroundWorkerInitializeConnectionByOid(Oid dboid, Oid useroid, uint32 flags) +{ + BackgroundWorker *worker = MyBgworkerEntry; + + /* XXX is this the right errcode? */ + if (!(worker->bgw_flags & BGWORKER_BACKEND_DATABASE_CONNECTION)) + ereport(FATAL, + (errcode(ERRCODE_PROGRAM_LIMIT_EXCEEDED), + errmsg("database connection requirement not indicated during registration"))); + + InitPostgres(NULL, dboid, /* database to connect to */ + NULL, useroid, /* role to connect as */ + false, /* never honor session_preload_libraries */ + (flags & BGWORKER_BYPASS_ALLOWCONN) != 0, /* ignore datallowconn? */ + NULL); /* no out_dbname */ + + /* it had better not gotten out of "init" mode yet */ + if (!IsInitProcessingMode()) + ereport(ERROR, + (errmsg("invalid processing mode in background worker"))); + SetProcessingMode(NormalProcessing); +} + +/* + * Block/unblock signals in a background worker + */ +void +BackgroundWorkerBlockSignals(void) +{ + PG_SETMASK(&BlockSig); +} + +void +BackgroundWorkerUnblockSignals(void) +{ + PG_SETMASK(&UnBlockSig); +} + +#ifdef EXEC_BACKEND +static pid_t +bgworker_forkexec(int shmem_slot) +{ + char *av[10]; + int ac = 0; + char forkav[MAXPGPATH]; + + snprintf(forkav, MAXPGPATH, "--forkbgworker=%d", shmem_slot); + + av[ac++] = "postgres"; + av[ac++] = forkav; + av[ac++] = NULL; /* filled in by postmaster_forkexec */ + av[ac] = NULL; + + Assert(ac < lengthof(av)); + + return postmaster_forkexec(ac, av); +} +#endif + +/* + * Start a new bgworker. + * Starting time conditions must have been checked already. + * + * Returns true on success, false on failure. + * In either case, update the RegisteredBgWorker's state appropriately. + * + * This code is heavily based on autovacuum.c, q.v. + */ +static bool +do_start_bgworker(RegisteredBgWorker *rw) +{ + pid_t worker_pid; + + Assert(rw->rw_pid == 0); + + /* + * Allocate and assign the Backend element. Note we must do this before + * forking, so that we can handle failures (out of memory or child-process + * slots) cleanly. + * + * Treat failure as though the worker had crashed. That way, the + * postmaster will wait a bit before attempting to start it again; if we + * tried again right away, most likely we'd find ourselves hitting the + * same resource-exhaustion condition. + */ + if (!assign_backendlist_entry(rw)) + { + rw->rw_crashed_at = GetCurrentTimestamp(); + return false; + } + + ereport(DEBUG1, + (errmsg_internal("starting background worker process \"%s\"", + rw->rw_worker.bgw_name))); + +#ifdef EXEC_BACKEND + switch ((worker_pid = bgworker_forkexec(rw->rw_shmem_slot))) +#else + switch ((worker_pid = fork_process())) +#endif + { + case -1: + /* in postmaster, fork failed ... */ + ereport(LOG, + (errmsg("could not fork worker process: %m"))); + /* undo what assign_backendlist_entry did */ + ReleasePostmasterChildSlot(rw->rw_child_slot); + rw->rw_child_slot = 0; + free(rw->rw_backend); + rw->rw_backend = NULL; + /* mark entry as crashed, so we'll try again later */ + rw->rw_crashed_at = GetCurrentTimestamp(); + break; + +#ifndef EXEC_BACKEND + case 0: + /* in postmaster child ... */ + InitPostmasterChild(); + + /* Close the postmaster's sockets */ + ClosePostmasterPorts(false); + + /* + * Before blowing away PostmasterContext, save this bgworker's + * data where it can find it. + */ + MyBgworkerEntry = (BackgroundWorker *) + MemoryContextAlloc(TopMemoryContext, sizeof(BackgroundWorker)); + memcpy(MyBgworkerEntry, &rw->rw_worker, sizeof(BackgroundWorker)); + + /* Release postmaster's working memory context */ + MemoryContextSwitchTo(TopMemoryContext); + MemoryContextDelete(PostmasterContext); + PostmasterContext = NULL; + + StartBackgroundWorker(); + + exit(1); /* should not get here */ + break; +#endif + default: + /* in postmaster, fork successful ... */ + rw->rw_pid = worker_pid; + rw->rw_backend->pid = rw->rw_pid; + ReportBackgroundWorkerPID(rw); + /* add new worker to lists of backends */ + dlist_push_head(&BackendList, &rw->rw_backend->elem); +#ifdef EXEC_BACKEND + ShmemBackendArrayAdd(rw->rw_backend); +#endif + return true; + } + + return false; +} + +/* + * Does the current postmaster state require starting a worker with the + * specified start_time? + */ +static bool +bgworker_should_start_now(BgWorkerStartTime start_time) +{ + switch (pmState) + { + case PM_NO_CHILDREN: + case PM_WAIT_DEAD_END: + case PM_SHUTDOWN_2: + case PM_SHUTDOWN: + case PM_WAIT_BACKENDS: + case PM_STOP_BACKENDS: + break; + + case PM_RUN: + if (start_time == BgWorkerStart_RecoveryFinished) + return true; + /* fall through */ + + case PM_HOT_STANDBY: + if (start_time == BgWorkerStart_ConsistentState) + return true; + /* fall through */ + + case PM_RECOVERY: + case PM_STARTUP: + case PM_INIT: + if (start_time == BgWorkerStart_PostmasterStart) + return true; + /* fall through */ + } + + return false; +} + +/* + * Allocate the Backend struct for a connected background worker, but don't + * add it to the list of backends just yet. + * + * On failure, return false without changing any worker state. + * + * Some info from the Backend is copied into the passed rw. + */ +static bool +assign_backendlist_entry(RegisteredBgWorker *rw) +{ + Backend *bn; + + /* + * Check that database state allows another connection. Currently the + * only possible failure is CAC_TOOMANY, so we just log an error message + * based on that rather than checking the error code precisely. + */ + if (canAcceptConnections(BACKEND_TYPE_BGWORKER) != CAC_OK) + { + ereport(LOG, + (errcode(ERRCODE_CONFIGURATION_LIMIT_EXCEEDED), + errmsg("no slot available for new worker process"))); + return false; + } + + /* + * Compute the cancel key that will be assigned to this session. We + * probably don't need cancel keys for background workers, but we'd better + * have something random in the field to prevent unfriendly people from + * sending cancels to them. + */ + if (!RandomCancelKey(&MyCancelKey)) + { + ereport(LOG, + (errcode(ERRCODE_INTERNAL_ERROR), + errmsg("could not generate random cancel key"))); + return false; + } + + bn = malloc(sizeof(Backend)); + if (bn == NULL) + { + ereport(LOG, + (errcode(ERRCODE_OUT_OF_MEMORY), + errmsg("out of memory"))); + return false; + } + + bn->cancel_key = MyCancelKey; + bn->child_slot = MyPMChildSlot = AssignPostmasterChildSlot(); + bn->bkend_type = BACKEND_TYPE_BGWORKER; + bn->dead_end = false; + bn->bgworker_notify = false; + + rw->rw_backend = bn; + rw->rw_child_slot = bn->child_slot; + + return true; +} + +/* + * If the time is right, start background worker(s). + * + * As a side effect, the bgworker control variables are set or reset + * depending on whether more workers may need to be started. + * + * We limit the number of workers started per call, to avoid consuming the + * postmaster's attention for too long when many such requests are pending. + * As long as StartWorkerNeeded is true, ServerLoop will not block and will + * call this function again after dealing with any other issues. + */ +static void +maybe_start_bgworkers(void) +{ +#define MAX_BGWORKERS_TO_LAUNCH 100 + int num_launched = 0; + TimestampTz now = 0; + slist_mutable_iter iter; + + /* + * During crash recovery, we have no need to be called until the state + * transition out of recovery. + */ + if (FatalError) + { + StartWorkerNeeded = false; + HaveCrashedWorker = false; + return; + } + + /* Don't need to be called again unless we find a reason for it below */ + StartWorkerNeeded = false; + HaveCrashedWorker = false; + + slist_foreach_modify(iter, &BackgroundWorkerList) + { + RegisteredBgWorker *rw; + + rw = slist_container(RegisteredBgWorker, rw_lnode, iter.cur); + + /* ignore if already running */ + if (rw->rw_pid != 0) + continue; + + /* if marked for death, clean up and remove from list */ + if (rw->rw_terminate) + { + ForgetBackgroundWorker(&iter); + continue; + } + + /* + * If this worker has crashed previously, maybe it needs to be + * restarted (unless on registration it specified it doesn't want to + * be restarted at all). Check how long ago did a crash last happen. + * If the last crash is too recent, don't start it right away; let it + * be restarted once enough time has passed. + */ + if (rw->rw_crashed_at != 0) + { + if (rw->rw_worker.bgw_restart_time == BGW_NEVER_RESTART) + { + int notify_pid; + + notify_pid = rw->rw_worker.bgw_notify_pid; + + ForgetBackgroundWorker(&iter); + + /* Report worker is gone now. */ + if (notify_pid != 0) + kill(notify_pid, SIGUSR1); + + continue; + } + + /* read system time only when needed */ + if (now == 0) + now = GetCurrentTimestamp(); + + if (!TimestampDifferenceExceeds(rw->rw_crashed_at, now, + rw->rw_worker.bgw_restart_time * 1000)) + { + /* Set flag to remember that we have workers to start later */ + HaveCrashedWorker = true; + continue; + } + } + + if (bgworker_should_start_now(rw->rw_worker.bgw_start_time)) + { + /* reset crash time before trying to start worker */ + rw->rw_crashed_at = 0; + + /* + * Try to start the worker. + * + * On failure, give up processing workers for now, but set + * StartWorkerNeeded so we'll come back here on the next iteration + * of ServerLoop to try again. (We don't want to wait, because + * there might be additional ready-to-run workers.) We could set + * HaveCrashedWorker as well, since this worker is now marked + * crashed, but there's no need because the next run of this + * function will do that. + */ + if (!do_start_bgworker(rw)) + { + StartWorkerNeeded = true; + return; + } + + /* + * If we've launched as many workers as allowed, quit, but have + * ServerLoop call us again to look for additional ready-to-run + * workers. There might not be any, but we'll find out the next + * time we run. + */ + if (++num_launched >= MAX_BGWORKERS_TO_LAUNCH) + { + StartWorkerNeeded = true; + return; + } + } + } +} + +/* + * When a backend asks to be notified about worker state changes, we + * set a flag in its backend entry. The background worker machinery needs + * to know when such backends exit. + */ +bool +PostmasterMarkPIDForWorkerNotify(int pid) +{ + dlist_iter iter; + Backend *bp; + + dlist_foreach(iter, &BackendList) + { + bp = dlist_container(Backend, elem, iter.cur); + if (bp->pid == pid) + { + bp->bgworker_notify = true; + return true; + } + } + return false; +} + +#ifdef EXEC_BACKEND + +/* + * The following need to be available to the save/restore_backend_variables + * functions. They are marked NON_EXEC_STATIC in their home modules. + */ +extern slock_t *ShmemLock; +extern slock_t *ProcStructLock; +extern PGPROC *AuxiliaryProcs; +extern PMSignalData *PMSignalState; +extern pg_time_t first_syslogger_file_time; + +#ifndef WIN32 +#define write_inheritable_socket(dest, src, childpid) ((*(dest) = (src)), true) +#define read_inheritable_socket(dest, src) (*(dest) = *(src)) +#else +static bool write_duplicated_handle(HANDLE *dest, HANDLE src, HANDLE child); +static bool write_inheritable_socket(InheritableSocket *dest, SOCKET src, + pid_t childPid); +static void read_inheritable_socket(SOCKET *dest, InheritableSocket *src); +#endif + + +/* Save critical backend variables into the BackendParameters struct */ +#ifndef WIN32 +static bool +save_backend_variables(BackendParameters *param, Port *port) +#else +static bool +save_backend_variables(BackendParameters *param, Port *port, + HANDLE childProcess, pid_t childPid) +#endif +{ + memcpy(¶m->port, port, sizeof(Port)); + if (!write_inheritable_socket(¶m->portsocket, port->sock, childPid)) + return false; + + strlcpy(param->DataDir, DataDir, MAXPGPATH); + + memcpy(¶m->ListenSocket, &ListenSocket, sizeof(ListenSocket)); + + param->MyCancelKey = MyCancelKey; + param->MyPMChildSlot = MyPMChildSlot; + +#ifdef WIN32 + param->ShmemProtectiveRegion = ShmemProtectiveRegion; +#endif + param->UsedShmemSegID = UsedShmemSegID; + param->UsedShmemSegAddr = UsedShmemSegAddr; + + param->ShmemLock = ShmemLock; + param->ShmemVariableCache = ShmemVariableCache; + param->ShmemBackendArray = ShmemBackendArray; + +#ifndef HAVE_SPINLOCKS + param->SpinlockSemaArray = SpinlockSemaArray; +#endif + param->NamedLWLockTrancheRequests = NamedLWLockTrancheRequests; + param->NamedLWLockTrancheArray = NamedLWLockTrancheArray; + param->MainLWLockArray = MainLWLockArray; + param->ProcStructLock = ProcStructLock; + param->ProcGlobal = ProcGlobal; + param->AuxiliaryProcs = AuxiliaryProcs; + param->PreparedXactProcs = PreparedXactProcs; + param->PMSignalState = PMSignalState; + + param->PostmasterPid = PostmasterPid; + param->PgStartTime = PgStartTime; + param->PgReloadTime = PgReloadTime; + param->first_syslogger_file_time = first_syslogger_file_time; + + param->redirection_done = redirection_done; + param->IsBinaryUpgrade = IsBinaryUpgrade; + param->query_id_enabled = query_id_enabled; + param->max_safe_fds = max_safe_fds; + + param->MaxBackends = MaxBackends; + +#ifdef WIN32 + param->PostmasterHandle = PostmasterHandle; + if (!write_duplicated_handle(¶m->initial_signal_pipe, + pgwin32_create_signal_listener(childPid), + childProcess)) + return false; +#else + memcpy(¶m->postmaster_alive_fds, &postmaster_alive_fds, + sizeof(postmaster_alive_fds)); +#endif + + memcpy(¶m->syslogPipe, &syslogPipe, sizeof(syslogPipe)); + + strlcpy(param->my_exec_path, my_exec_path, MAXPGPATH); + + strlcpy(param->pkglib_path, pkglib_path, MAXPGPATH); + + return true; +} + + +#ifdef WIN32 +/* + * Duplicate a handle for usage in a child process, and write the child + * process instance of the handle to the parameter file. + */ +static bool +write_duplicated_handle(HANDLE *dest, HANDLE src, HANDLE childProcess) +{ + HANDLE hChild = INVALID_HANDLE_VALUE; + + if (!DuplicateHandle(GetCurrentProcess(), + src, + childProcess, + &hChild, + 0, + TRUE, + DUPLICATE_CLOSE_SOURCE | DUPLICATE_SAME_ACCESS)) + { + ereport(LOG, + (errmsg_internal("could not duplicate handle to be written to backend parameter file: error code %lu", + GetLastError()))); + return false; + } + + *dest = hChild; + return true; +} + +/* + * Duplicate a socket for usage in a child process, and write the resulting + * structure to the parameter file. + * This is required because a number of LSPs (Layered Service Providers) very + * common on Windows (antivirus, firewalls, download managers etc) break + * straight socket inheritance. + */ +static bool +write_inheritable_socket(InheritableSocket *dest, SOCKET src, pid_t childpid) +{ + dest->origsocket = src; + if (src != 0 && src != PGINVALID_SOCKET) + { + /* Actual socket */ + if (WSADuplicateSocket(src, childpid, &dest->wsainfo) != 0) + { + ereport(LOG, + (errmsg("could not duplicate socket %d for use in backend: error code %d", + (int) src, WSAGetLastError()))); + return false; + } + } + return true; +} + +/* + * Read a duplicate socket structure back, and get the socket descriptor. + */ +static void +read_inheritable_socket(SOCKET *dest, InheritableSocket *src) +{ + SOCKET s; + + if (src->origsocket == PGINVALID_SOCKET || src->origsocket == 0) + { + /* Not a real socket! */ + *dest = src->origsocket; + } + else + { + /* Actual socket, so create from structure */ + s = WSASocket(FROM_PROTOCOL_INFO, + FROM_PROTOCOL_INFO, + FROM_PROTOCOL_INFO, + &src->wsainfo, + 0, + 0); + if (s == INVALID_SOCKET) + { + write_stderr("could not create inherited socket: error code %d\n", + WSAGetLastError()); + exit(1); + } + *dest = s; + + /* + * To make sure we don't get two references to the same socket, close + * the original one. (This would happen when inheritance actually + * works.. + */ + closesocket(src->origsocket); + } +} +#endif + +static void +read_backend_variables(char *id, Port *port) +{ + BackendParameters param; + +#ifndef WIN32 + /* Non-win32 implementation reads from file */ + FILE *fp; + + /* Open file */ + fp = AllocateFile(id, PG_BINARY_R); + if (!fp) + { + write_stderr("could not open backend variables file \"%s\": %s\n", + id, strerror(errno)); + exit(1); + } + + if (fread(¶m, sizeof(param), 1, fp) != 1) + { + write_stderr("could not read from backend variables file \"%s\": %s\n", + id, strerror(errno)); + exit(1); + } + + /* Release file */ + FreeFile(fp); + if (unlink(id) != 0) + { + write_stderr("could not remove file \"%s\": %s\n", + id, strerror(errno)); + exit(1); + } +#else + /* Win32 version uses mapped file */ + HANDLE paramHandle; + BackendParameters *paramp; + +#ifdef _WIN64 + paramHandle = (HANDLE) _atoi64(id); +#else + paramHandle = (HANDLE) atol(id); +#endif + paramp = MapViewOfFile(paramHandle, FILE_MAP_READ, 0, 0, 0); + if (!paramp) + { + write_stderr("could not map view of backend variables: error code %lu\n", + GetLastError()); + exit(1); + } + + memcpy(¶m, paramp, sizeof(BackendParameters)); + + if (!UnmapViewOfFile(paramp)) + { + write_stderr("could not unmap view of backend variables: error code %lu\n", + GetLastError()); + exit(1); + } + + if (!CloseHandle(paramHandle)) + { + write_stderr("could not close handle to backend parameter variables: error code %lu\n", + GetLastError()); + exit(1); + } +#endif + + restore_backend_variables(¶m, port); +} + +/* Restore critical backend variables from the BackendParameters struct */ +static void +restore_backend_variables(BackendParameters *param, Port *port) +{ + memcpy(port, ¶m->port, sizeof(Port)); + read_inheritable_socket(&port->sock, ¶m->portsocket); + + SetDataDir(param->DataDir); + + memcpy(&ListenSocket, ¶m->ListenSocket, sizeof(ListenSocket)); + + MyCancelKey = param->MyCancelKey; + MyPMChildSlot = param->MyPMChildSlot; + +#ifdef WIN32 + ShmemProtectiveRegion = param->ShmemProtectiveRegion; +#endif + UsedShmemSegID = param->UsedShmemSegID; + UsedShmemSegAddr = param->UsedShmemSegAddr; + + ShmemLock = param->ShmemLock; + ShmemVariableCache = param->ShmemVariableCache; + ShmemBackendArray = param->ShmemBackendArray; + +#ifndef HAVE_SPINLOCKS + SpinlockSemaArray = param->SpinlockSemaArray; +#endif + NamedLWLockTrancheRequests = param->NamedLWLockTrancheRequests; + NamedLWLockTrancheArray = param->NamedLWLockTrancheArray; + MainLWLockArray = param->MainLWLockArray; + ProcStructLock = param->ProcStructLock; + ProcGlobal = param->ProcGlobal; + AuxiliaryProcs = param->AuxiliaryProcs; + PreparedXactProcs = param->PreparedXactProcs; + PMSignalState = param->PMSignalState; + + PostmasterPid = param->PostmasterPid; + PgStartTime = param->PgStartTime; + PgReloadTime = param->PgReloadTime; + first_syslogger_file_time = param->first_syslogger_file_time; + + redirection_done = param->redirection_done; + IsBinaryUpgrade = param->IsBinaryUpgrade; + query_id_enabled = param->query_id_enabled; + max_safe_fds = param->max_safe_fds; + + MaxBackends = param->MaxBackends; + +#ifdef WIN32 + PostmasterHandle = param->PostmasterHandle; + pgwin32_initial_signal_pipe = param->initial_signal_pipe; +#else + memcpy(&postmaster_alive_fds, ¶m->postmaster_alive_fds, + sizeof(postmaster_alive_fds)); +#endif + + memcpy(&syslogPipe, ¶m->syslogPipe, sizeof(syslogPipe)); + + strlcpy(my_exec_path, param->my_exec_path, MAXPGPATH); + + strlcpy(pkglib_path, param->pkglib_path, MAXPGPATH); + + /* + * We need to restore fd.c's counts of externally-opened FDs; to avoid + * confusion, be sure to do this after restoring max_safe_fds. (Note: + * BackendInitialize will handle this for port->sock.) + */ +#ifndef WIN32 + if (postmaster_alive_fds[0] >= 0) + ReserveExternalFD(); + if (postmaster_alive_fds[1] >= 0) + ReserveExternalFD(); +#endif +} + + +Size +ShmemBackendArraySize(void) +{ + return mul_size(MaxLivePostmasterChildren(), sizeof(Backend)); +} + +void +ShmemBackendArrayAllocation(void) +{ + Size size = ShmemBackendArraySize(); + + ShmemBackendArray = (Backend *) ShmemAlloc(size); + /* Mark all slots as empty */ + memset(ShmemBackendArray, 0, size); +} + +static void +ShmemBackendArrayAdd(Backend *bn) +{ + /* The array slot corresponding to my PMChildSlot should be free */ + int i = bn->child_slot - 1; + + Assert(ShmemBackendArray[i].pid == 0); + ShmemBackendArray[i] = *bn; +} + +static void +ShmemBackendArrayRemove(Backend *bn) +{ + int i = bn->child_slot - 1; + + Assert(ShmemBackendArray[i].pid == bn->pid); + /* Mark the slot as empty */ + ShmemBackendArray[i].pid = 0; +} +#endif /* EXEC_BACKEND */ + + +#ifdef WIN32 + +/* + * Subset implementation of waitpid() for Windows. We assume pid is -1 + * (that is, check all child processes) and options is WNOHANG (don't wait). + */ +static pid_t +waitpid(pid_t pid, int *exitstatus, int options) +{ + win32_deadchild_waitinfo *childinfo; + DWORD exitcode; + DWORD dwd; + ULONG_PTR key; + OVERLAPPED *ovl; + + /* Try to consume one win32_deadchild_waitinfo from the queue. */ + if (!GetQueuedCompletionStatus(win32ChildQueue, &dwd, &key, &ovl, 0)) + { + errno = EAGAIN; + return -1; + } + + childinfo = (win32_deadchild_waitinfo *) key; + pid = childinfo->procId; + + /* + * Remove handle from wait - required even though it's set to wait only + * once + */ + UnregisterWaitEx(childinfo->waitHandle, NULL); + + if (!GetExitCodeProcess(childinfo->procHandle, &exitcode)) + { + /* + * Should never happen. Inform user and set a fixed exitcode. + */ + write_stderr("could not read exit code for process\n"); + exitcode = 255; + } + *exitstatus = exitcode; + + /* + * Close the process handle. Only after this point can the PID can be + * recycled by the kernel. + */ + CloseHandle(childinfo->procHandle); + + /* + * Free struct that was allocated before the call to + * RegisterWaitForSingleObject() + */ + pfree(childinfo); + + return pid; +} + +/* + * Note! Code below executes on a thread pool! All operations must + * be thread safe! Note that elog() and friends must *not* be used. + */ +static void WINAPI +pgwin32_deadchild_callback(PVOID lpParameter, BOOLEAN TimerOrWaitFired) +{ + /* Should never happen, since we use INFINITE as timeout value. */ + if (TimerOrWaitFired) + return; + + /* + * Post the win32_deadchild_waitinfo object for waitpid() to deal with. If + * that fails, we leak the object, but we also leak a whole process and + * get into an unrecoverable state, so there's not much point in worrying + * about that. We'd like to panic, but we can't use that infrastructure + * from this thread. + */ + if (!PostQueuedCompletionStatus(win32ChildQueue, + 0, + (ULONG_PTR) lpParameter, + NULL)) + write_stderr("could not post child completion status\n"); + + /* Queue SIGCHLD signal. */ + pg_queue_signal(SIGCHLD); +} +#endif /* WIN32 */ + +/* + * Initialize one and only handle for monitoring postmaster death. + * + * Called once in the postmaster, so that child processes can subsequently + * monitor if their parent is dead. + */ +static void +InitPostmasterDeathWatchHandle(void) +{ +#ifndef WIN32 + + /* + * Create a pipe. Postmaster holds the write end of the pipe open + * (POSTMASTER_FD_OWN), and children hold the read end. Children can pass + * the read file descriptor to select() to wake up in case postmaster + * dies, or check for postmaster death with a (read() == 0). Children must + * close the write end as soon as possible after forking, because EOF + * won't be signaled in the read end until all processes have closed the + * write fd. That is taken care of in ClosePostmasterPorts(). + */ + Assert(MyProcPid == PostmasterPid); + if (pipe(postmaster_alive_fds) < 0) + ereport(FATAL, + (errcode_for_file_access(), + errmsg_internal("could not create pipe to monitor postmaster death: %m"))); + + /* Notify fd.c that we've eaten two FDs for the pipe. */ + ReserveExternalFD(); + ReserveExternalFD(); + + /* + * Set O_NONBLOCK to allow testing for the fd's presence with a read() + * call. + */ + if (fcntl(postmaster_alive_fds[POSTMASTER_FD_WATCH], F_SETFL, O_NONBLOCK) == -1) + ereport(FATAL, + (errcode_for_socket_access(), + errmsg_internal("could not set postmaster death monitoring pipe to nonblocking mode: %m"))); +#else + + /* + * On Windows, we use a process handle for the same purpose. + */ + if (DuplicateHandle(GetCurrentProcess(), + GetCurrentProcess(), + GetCurrentProcess(), + &PostmasterHandle, + 0, + TRUE, + DUPLICATE_SAME_ACCESS) == 0) + ereport(FATAL, + (errmsg_internal("could not duplicate postmaster handle: error code %lu", + GetLastError()))); +#endif /* WIN32 */ +} |