/*-------------------------------------------------------------------------

 *

 * xlogfuncs.c

 *

 * PostgreSQL write-ahead log manager user interface functions

 *

 * This file contains WAL control and information functions.

 *

 *

 * Portions Copyright (c) 1996-2026, PostgreSQL Global Development Group

 * Portions Copyright (c) 1994, Regents of the University of California

 *

 * src/backend/access/transam/xlogfuncs.c

 *

 *-------------------------------------------------------------------------

 */

#include "postgres.h"

#include <unistd.h>

#include "access/htup_details.h"

#include "access/xlog_internal.h"

#include "access/xlogbackup.h"

#include "access/xlogrecovery.h"

#include "catalog/pg_authid.h"

#include "catalog/pg_type.h"

#include "funcapi.h"

#include "miscadmin.h"

#include "pgstat.h"

#include "utils/acl.h"

#include "replication/walreceiver.h"

#include "storage/fd.h"

#include "storage/latch.h"

#include "storage/standby.h"

#include "utils/builtins.h"

#include "utils/memutils.h"

#include "utils/pg_lsn.h"

#include "utils/timestamp.h"

#include "utils/wait_event.h"

/*

 * Backup-related variables.

 */

static BackupState *backup_state = NULL;

static StringInfo tablespace_map = NULL;

/* Session-level context for the SQL-callable backup functions */

static MemoryContext backupcontext = NULL;

/*

 * Return a string constant representing the recovery pause state. This is

 * used in system functions and views, and should *not* be translated.

 */

static const char *

GetRecoveryPauseStateString(RecoveryPauseState pause_state)

{

  const char *statestr = NULL;

  switch (pause_state)

  {

    case RECOVERY_NOT_PAUSED:

      statestr = "not paused";

      break;

    case RECOVERY_PAUSE_REQUESTED:

      statestr = "pause requested";

      break;

    case RECOVERY_PAUSED:

      statestr = "paused";

      break;

  }

  Assert(statestr != NULL);

  return statestr;

}

/*

 * pg_backup_start: set up for taking an on-line backup dump

 *

 * Essentially what this does is to create the contents required for the

 * backup_label file and the tablespace map.

 *

 * Permission checking for this function is managed through the normal

 * GRANT system.

 */

Datum

pg_backup_start(PG_FUNCTION_ARGS)

{

  text     *backupid = PG_GETARG_TEXT_PP(0);

  bool    fast = PG_GETARG_BOOL(1);

  char     *backupidstr;

  SessionBackupState status = get_backup_status();

  MemoryContext oldcontext;

  backupidstr = text_to_cstring(backupid);

  if (status == SESSION_BACKUP_RUNNING)

    ereport(ERROR,

        (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),

         errmsg("a backup is already in progress in this session")));

  /*

   * backup_state and tablespace_map need to be long-lived as they are used

   * in pg_backup_stop().  These are allocated in a dedicated memory context

   * child of TopMemoryContext, deleted at the end of pg_backup_stop().  If

   * an error happens before ending the backup, memory would be leaked in

   * this context until pg_backup_start() is called again.

   */

  if (backupcontext == NULL)

  {

    backupcontext = AllocSetContextCreate(TopMemoryContext,

                        "on-line backup context",

                        ALLOCSET_START_SMALL_SIZES);

  }

  else

  {

    backup_state = NULL;

    tablespace_map = NULL;

    MemoryContextReset(backupcontext);

  }

  oldcontext = MemoryContextSwitchTo(backupcontext);

  backup_state = palloc0_object(BackupState);

  tablespace_map = makeStringInfo();

  MemoryContextSwitchTo(oldcontext);

  register_persistent_abort_backup_handler();

  do_pg_backup_start(backupidstr, fast, NULL, backup_state, tablespace_map);

  PG_RETURN_LSN(backup_state->startpoint);

}

/*

 * pg_backup_stop: finish taking an on-line backup.

 *

 * The first parameter (variable 'waitforarchive'), which is optional,

 * allows the user to choose if they want to wait for the WAL to be archived

 * or if we should just return as soon as the WAL record is written.

 *

 * This function stops an in-progress backup, creates backup_label contents and

 * it returns the backup stop LSN, backup_label and tablespace_map contents.

 *

 * The backup_label contains the user-supplied label string (typically this

 * would be used to tell where the backup dump will be stored), the starting

 * time, starting WAL location for the dump and so on.  It is the caller's

 * responsibility to write the backup_label and tablespace_map files in the

 * data folder that will be restored from this backup.

 *

 * Permission checking for this function is managed through the normal

 * GRANT system.

 */

Datum

pg_backup_stop(PG_FUNCTION_ARGS)

{

#define PG_BACKUP_STOP_V2_COLS 3

  TupleDesc tupdesc;

  Datum   values[PG_BACKUP_STOP_V2_COLS] = {0};

  bool    nulls[PG_BACKUP_STOP_V2_COLS] = {0};

  bool    waitforarchive = PG_GETARG_BOOL(0);

  char     *backup_label;

  SessionBackupState status = get_backup_status();

  /* Initialize attributes information in the tuple descriptor */

  if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)

    elog(ERROR, "return type must be a row type");

  if (status != SESSION_BACKUP_RUNNING)

    ereport(ERROR,

        (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),

         errmsg("backup is not in progress"),

         errhint("Did you call pg_backup_start()?")));

  Assert(backup_state != NULL);

  Assert(tablespace_map != NULL);

  /* Stop the backup */

  do_pg_backup_stop(backup_state, waitforarchive);

  /* Build the contents of backup_label */

  backup_label = build_backup_content(backup_state, false);

  values[0] = LSNGetDatum(backup_state->stoppoint);

  values[1] = CStringGetTextDatum(backup_label);

  values[2] = CStringGetTextDatum(tablespace_map->data);

  /* Deallocate backup-related variables */

  pfree(backup_label);

  /* Clean up the session-level state and its memory context */

  backup_state = NULL;

  tablespace_map = NULL;

  MemoryContextDelete(backupcontext);

  backupcontext = NULL;

  /* Returns the record as Datum */

  PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));

}

/*

 * pg_switch_wal: switch to next xlog file

 *

 * Permission checking for this function is managed through the normal

 * GRANT system.

 */

Datum

pg_switch_wal(PG_FUNCTION_ARGS)

{

  XLogRecPtr  switchpoint;

  if (RecoveryInProgress())

    ereport(ERROR,

        (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),

         errmsg("recovery is in progress"),

         errhint("WAL control functions cannot be executed during recovery.")));

  switchpoint = RequestXLogSwitch(false);

  /*

   * As a convenience, return the WAL location of the switch record

   */

  PG_RETURN_LSN(switchpoint);

}

/*

 * pg_log_standby_snapshot: call LogStandbySnapshot()

 *

 * Permission checking for this function is managed through the normal

 * GRANT system.

 */

Datum

pg_log_standby_snapshot(PG_FUNCTION_ARGS)

{

  XLogRecPtr  recptr;

  if (RecoveryInProgress())

    ereport(ERROR,

        (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),

         errmsg("recovery is in progress"),

         errhint("%s cannot be executed during recovery.",

             "pg_log_standby_snapshot()")));

  if (!XLogStandbyInfoActive())

    ereport(ERROR,

        (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),

         errmsg("pg_log_standby_snapshot() can only be used if \"wal_level\" >= \"replica\"")));

  recptr = LogStandbySnapshot();

  /*

   * As a convenience, return the WAL location of the last inserted record

   */

  PG_RETURN_LSN(recptr);

}

/*

 * pg_create_restore_point: a named point for restore

 *

 * Permission checking for this function is managed through the normal

 * GRANT system.

 */

Datum

pg_create_restore_point(PG_FUNCTION_ARGS)

{

  text     *restore_name = PG_GETARG_TEXT_PP(0);

  char     *restore_name_str;

  XLogRecPtr  restorepoint;

  if (RecoveryInProgress())

    ereport(ERROR,

        (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),

         errmsg("recovery is in progress"),

         errhint("WAL control functions cannot be executed during recovery.")));

  if (!XLogIsNeeded())

    ereport(ERROR,

        (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),

         errmsg("WAL level not sufficient for creating a restore point"),

         errhint("\"wal_level\" must be set to \"replica\" or \"logical\" at server start.")));

  restore_name_str = text_to_cstring(restore_name);

  if (strlen(restore_name_str) >= MAXFNAMELEN)

    ereport(ERROR,

        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),

         errmsg("value too long for restore point (maximum %d characters)", MAXFNAMELEN - 1)));

  restorepoint = XLogRestorePoint(restore_name_str);

  /*

   * As a convenience, return the WAL location of the restore point record

   */

  PG_RETURN_LSN(restorepoint);

}

/*

 * Report the current WAL write location (same format as pg_backup_start etc)

 *

 * This is useful for determining how much of WAL is visible to an external

 * archiving process.  Note that the data before this point is written out

 * to the kernel, but is not necessarily synced to disk.

 */

Datum

pg_current_wal_lsn(PG_FUNCTION_ARGS)

{

  XLogRecPtr  current_recptr;

  if (RecoveryInProgress())

    ereport(ERROR,

        (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),

         errmsg("recovery is in progress"),

         errhint("WAL control functions cannot be executed during recovery.")));

  current_recptr = GetXLogWriteRecPtr();

  PG_RETURN_LSN(current_recptr);

}

/*

 * Report the current WAL insert location (same format as pg_backup_start etc)

 *

 * This function is mostly for debugging purposes.

 */

Datum

pg_current_wal_insert_lsn(PG_FUNCTION_ARGS)

{

  XLogRecPtr  current_recptr;

  if (RecoveryInProgress())

    ereport(ERROR,

        (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),

         errmsg("recovery is in progress"),

         errhint("WAL control functions cannot be executed during recovery.")));

  current_recptr = GetXLogInsertRecPtr();

  PG_RETURN_LSN(current_recptr);

}

/*

 * Report the current WAL flush location (same format as pg_backup_start etc)

 *

 * This function is mostly for debugging purposes.

 */

Datum

pg_current_wal_flush_lsn(PG_FUNCTION_ARGS)

{

  XLogRecPtr  current_recptr;

  if (RecoveryInProgress())

    ereport(ERROR,

        (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),

         errmsg("recovery is in progress"),

         errhint("WAL control functions cannot be executed during recovery.")));

  current_recptr = GetFlushRecPtr(NULL);

  PG_RETURN_LSN(current_recptr);

}

/*

 * Report the last WAL receive location (same format as pg_backup_start etc)

 *

 * This is useful for determining how much of WAL is guaranteed to be received

 * and synced to disk by walreceiver.

 */

Datum

pg_last_wal_receive_lsn(PG_FUNCTION_ARGS)

{

  XLogRecPtr  recptr;

  recptr = GetWalRcvFlushRecPtr(NULL, NULL);

  if (!XLogRecPtrIsValid(recptr))

    PG_RETURN_NULL();

  PG_RETURN_LSN(recptr);

}

/*

 * Report the last WAL replay location (same format as pg_backup_start etc)

 *

 * This is useful for determining how much of WAL is visible to read-only

 * connections during recovery.

 */

Datum

pg_last_wal_replay_lsn(PG_FUNCTION_ARGS)

{

  XLogRecPtr  recptr;

  recptr = GetXLogReplayRecPtr(NULL);

  if (!XLogRecPtrIsValid(recptr))

    PG_RETURN_NULL();

  PG_RETURN_LSN(recptr);

}

/*

 * Compute an xlog file name and decimal byte offset given a WAL location,

 * such as is returned by pg_backup_stop() or pg_switch_wal().

 */

Datum

pg_walfile_name_offset(PG_FUNCTION_ARGS)

{

  XLogSegNo xlogsegno;

  uint32    xrecoff;

  XLogRecPtr  locationpoint = PG_GETARG_LSN(0);

  char    xlogfilename[MAXFNAMELEN];

  Datum   values[2];

  bool    isnull[2];

  TupleDesc resultTupleDesc;

  HeapTuple resultHeapTuple;

  Datum   result;

  if (RecoveryInProgress())

    ereport(ERROR,

        (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),

         errmsg("recovery is in progress"),

         errhint("%s cannot be executed during recovery.",

             "pg_walfile_name_offset()")));

  /*

   * Construct a tuple descriptor for the result row.  This must match this

   * function's pg_proc entry!

   */

  resultTupleDesc = CreateTemplateTupleDesc(2);

  TupleDescInitEntry(resultTupleDesc, (AttrNumber) 1, "file_name",

             TEXTOID, -1, 0);

  TupleDescInitEntry(resultTupleDesc, (AttrNumber) 2, "file_offset",

             INT4OID, -1, 0);

  TupleDescFinalize(resultTupleDesc);

  resultTupleDesc = BlessTupleDesc(resultTupleDesc);

  /*

   * xlogfilename

   */

  XLByteToSeg(locationpoint, xlogsegno, wal_segment_size);

  XLogFileName(xlogfilename, GetWALInsertionTimeLine(), xlogsegno,

         wal_segment_size);

  values[0] = CStringGetTextDatum(xlogfilename);

  isnull[0] = false;

  /*

   * offset

   */

  xrecoff = XLogSegmentOffset(locationpoint, wal_segment_size);

  values[1] = Int32GetDatum(xrecoff);

  isnull[1] = false;

  /*

   * Tuple jam: Having first prepared your Datums, then squash together

   */

  resultHeapTuple = heap_form_tuple(resultTupleDesc, values, isnull);

  result = HeapTupleGetDatum(resultHeapTuple);

  PG_RETURN_DATUM(result);

}

/*

 * Compute an xlog file name given a WAL location,

 * such as is returned by pg_backup_stop() or pg_switch_wal().

 */

Datum

pg_walfile_name(PG_FUNCTION_ARGS)

{

  XLogSegNo xlogsegno;

  XLogRecPtr  locationpoint = PG_GETARG_LSN(0);

  char    xlogfilename[MAXFNAMELEN];

  if (RecoveryInProgress())

    ereport(ERROR,

        (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),

         errmsg("recovery is in progress"),

         errhint("%s cannot be executed during recovery.",

             "pg_walfile_name()")));

  XLByteToSeg(locationpoint, xlogsegno, wal_segment_size);

  XLogFileName(xlogfilename, GetWALInsertionTimeLine(), xlogsegno,

         wal_segment_size);

  PG_RETURN_TEXT_P(cstring_to_text(xlogfilename));

}

/*

 * Extract the sequence number and the timeline ID from given a WAL file

 * name.

 */

Datum

pg_split_walfile_name(PG_FUNCTION_ARGS)

{

#define PG_SPLIT_WALFILE_NAME_COLS 2

  char     *fname = text_to_cstring(PG_GETARG_TEXT_PP(0));

  char     *fname_upper;

  char     *p;

  TimeLineID  tli;

  XLogSegNo segno;

  Datum   values[PG_SPLIT_WALFILE_NAME_COLS] = {0};

  bool    isnull[PG_SPLIT_WALFILE_NAME_COLS] = {0};

  TupleDesc tupdesc;

  HeapTuple tuple;

  char    buf[256];

  Datum   result;

  fname_upper = pstrdup(fname);

  /* Capitalize WAL file name. */

  for (p = fname_upper; *p; p++)

    *p = pg_ascii_toupper((unsigned char) *p);

  if (!IsXLogFileName(fname_upper))

    ereport(ERROR,

        (errcode(ERRCODE_INVALID_PARAMETER_VALUE),

         errmsg("invalid WAL file name \"%s\"", fname)));

  XLogFromFileName(fname_upper, &tli, &segno, wal_segment_size);

  if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)

    elog(ERROR, "return type must be a row type");

  /* Convert to numeric. */

  snprintf(buf, sizeof buf, UINT64_FORMAT, segno);

  values[0] = DirectFunctionCall3(numeric_in,

                  CStringGetDatum(buf),

                  ObjectIdGetDatum(0),

                  Int32GetDatum(-1));

  values[1] = Int64GetDatum(tli);

  tuple = heap_form_tuple(tupdesc, values, isnull);

  result = HeapTupleGetDatum(tuple);

  PG_RETURN_DATUM(result);

#undef PG_SPLIT_WALFILE_NAME_COLS

}

/*

 * pg_wal_replay_pause - Request to pause recovery

 *

 * Permission checking for this function is managed through the normal

 * GRANT system.

 */

Datum

pg_wal_replay_pause(PG_FUNCTION_ARGS)

{

  if (!RecoveryInProgress())

    ereport(ERROR,

        (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),

         errmsg("recovery is not in progress"),

         errhint("Recovery control functions can only be executed during recovery.")));

  if (PromoteIsTriggered())

    ereport(ERROR,

        (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),

         errmsg("standby promotion is ongoing"),

         errhint("%s cannot be executed after promotion is triggered.",

             "pg_wal_replay_pause()")));

  SetRecoveryPause(true);

  /* wake up the recovery process so that it can process the pause request */

  WakeupRecovery();

  PG_RETURN_VOID();

}

/*

 * pg_wal_replay_resume - resume recovery now

 *

 * Permission checking for this function is managed through the normal

 * GRANT system.

 */

Datum

pg_wal_replay_resume(PG_FUNCTION_ARGS)

{

  if (!RecoveryInProgress())

    ereport(ERROR,

        (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),

         errmsg("recovery is not in progress"),

         errhint("Recovery control functions can only be executed during recovery.")));

  if (PromoteIsTriggered())

    ereport(ERROR,

        (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),

         errmsg("standby promotion is ongoing"),

         errhint("%s cannot be executed after promotion is triggered.",

             "pg_wal_replay_resume()")));

  SetRecoveryPause(false);

  PG_RETURN_VOID();

}

/*

 * pg_is_wal_replay_paused

 */

Datum

pg_is_wal_replay_paused(PG_FUNCTION_ARGS)

{

  if (!RecoveryInProgress())

    ereport(ERROR,

        (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),

         errmsg("recovery is not in progress"),

         errhint("Recovery control functions can only be executed during recovery.")));

  PG_RETURN_BOOL(GetRecoveryPauseState() != RECOVERY_NOT_PAUSED);

}

/*

 * pg_get_wal_replay_pause_state - Returns the recovery pause state.

 *

 * Returned values:

 *

 * 'not paused' - if pause is not requested

 * 'pause requested' - if pause is requested but recovery is not yet paused

 * 'paused' - if recovery is paused

 */

Datum

pg_get_wal_replay_pause_state(PG_FUNCTION_ARGS)

{

  RecoveryPauseState state;

  if (!RecoveryInProgress())

    ereport(ERROR,

        (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),

         errmsg("recovery is not in progress"),

         errhint("Recovery control functions can only be executed during recovery.")));

  state = GetRecoveryPauseState();

  /* get the recovery pause state */

  PG_RETURN_TEXT_P(cstring_to_text(GetRecoveryPauseStateString(state)));

}

/*

 * Returns timestamp of latest processed commit/abort record.

 *

 * When the server has been started normally without recovery the function

 * returns NULL.

 */

Datum

pg_last_xact_replay_timestamp(PG_FUNCTION_ARGS)

{

  TimestampTz xtime;

  xtime = GetLatestXTime();

  if (xtime == 0)

    PG_RETURN_NULL();

  PG_RETURN_TIMESTAMPTZ(xtime);

}

/*

 * Returns bool with current recovery mode, a global state.

 */

Datum

pg_is_in_recovery(PG_FUNCTION_ARGS)

{

  PG_RETURN_BOOL(RecoveryInProgress());

}

/*

 * Compute the difference in bytes between two WAL locations.

 */

Datum

pg_wal_lsn_diff(PG_FUNCTION_ARGS)

{

  Datum   result;

  result = DirectFunctionCall2(pg_lsn_mi,

                 PG_GETARG_DATUM(0),

                 PG_GETARG_DATUM(1));

  PG_RETURN_DATUM(result);

}

/*

 * Promotes a standby server.

 *

 * A result of "true" means that promotion has been completed if "wait" is

 * "true", or initiated if "wait" is false.

 */

Datum

pg_promote(PG_FUNCTION_ARGS)

{

  bool    wait = PG_GETARG_BOOL(0);

  int     wait_seconds = PG_GETARG_INT32(1);

  FILE     *promote_file;

  TimestampTz end_time;

  if (!RecoveryInProgress())

    ereport(ERROR,

        (errcode(ERRCODE_OBJECT_NOT_IN_PREREQUISITE_STATE),

         errmsg("recovery is not in progress"),

         errhint("Recovery control functions can only be executed during recovery.")));

  if (wait_seconds <= 0)

    ereport(ERROR,

        (errcode(ERRCODE_NUMERIC_VALUE_OUT_OF_RANGE),

         errmsg("\"wait_seconds\" must not be negative or zero")));

  /* create the promote signal file */

  promote_file = AllocateFile(PROMOTE_SIGNAL_FILE, "w");

  if (!promote_file)

    ereport(ERROR,

        (errcode_for_file_access(),

         errmsg("could not create file \"%s\": %m",

            PROMOTE_SIGNAL_FILE)));

  if (FreeFile(promote_file))

    ereport(ERROR,

        (errcode_for_file_access(),

         errmsg("could not write file \"%s\": %m",

            PROMOTE_SIGNAL_FILE)));

  /* signal the postmaster */

  if (kill(PostmasterPid, SIGUSR1) != 0)

  {

    (void) unlink(PROMOTE_SIGNAL_FILE);

    ereport(ERROR,

        (errcode(ERRCODE_SYSTEM_ERROR),

         errmsg("failed to send signal to postmaster: %m")));

  }

  /* return immediately if waiting was not requested */

  if (!wait)

    PG_RETURN_BOOL(true);

  /* wait for the amount of time wanted until promotion */

  end_time = TimestampTzPlusSeconds(GetCurrentTimestamp(), wait_seconds);

  while (GetCurrentTimestamp() < end_time)

  {

    int     rc;

    ResetLatch(MyLatch);

    if (!RecoveryInProgress())

      PG_RETURN_BOOL(true);

    CHECK_FOR_INTERRUPTS();

    rc = WaitLatch(MyLatch,

             WL_LATCH_SET | WL_TIMEOUT | WL_POSTMASTER_DEATH,

             100L,

             WAIT_EVENT_PROMOTE);

    /*

     * Emergency bailout if postmaster has died.  This is to avoid the

     * necessity for manual cleanup of all postmaster children.

     */

    if (rc & WL_POSTMASTER_DEATH)

      ereport(FATAL,

          (errcode(ERRCODE_ADMIN_SHUTDOWN),

           errmsg("terminating connection due to unexpected postmaster exit"),

           errcontext("while waiting on promotion")));

  }

  ereport(WARNING,

      (errmsg_plural("server did not promote within %d second",

               "server did not promote within %d seconds",

               wait_seconds,

               wait_seconds)));

  PG_RETURN_BOOL(false);

}

/*

 * pg_stat_get_recovery - returns information about WAL recovery state

 *

 * Returns NULL when not in recovery or when the caller lacks

 * pg_read_all_stats privileges; one row otherwise.

 */

Datum

pg_stat_get_recovery(PG_FUNCTION_ARGS)

{

  TupleDesc tupdesc;

  Datum    *values;

  bool     *nulls;

  /* Local copies of shared state */

  bool    promote_triggered;

  XLogRecPtr  last_replayed_read_lsn;

  XLogRecPtr  last_replayed_end_lsn;

  TimeLineID  last_replayed_tli;

  XLogRecPtr  replay_end_lsn;

  TimeLineID  replay_end_tli;

  TimestampTz recovery_last_xact_time;

  TimestampTz current_chunk_start_time;

  RecoveryPauseState pause_state;

  if (!RecoveryInProgress())

    PG_RETURN_NULL();

  if (!has_privs_of_role(GetUserId(), ROLE_PG_READ_ALL_STATS))

    PG_RETURN_NULL();

  /* Take a lock to ensure value consistency */

  SpinLockAcquire(&XLogRecoveryCtl->info_lck);

  promote_triggered = XLogRecoveryCtl->SharedPromoteIsTriggered;

  last_replayed_read_lsn = XLogRecoveryCtl->lastReplayedReadRecPtr;

  last_replayed_end_lsn = XLogRecoveryCtl->lastReplayedEndRecPtr;

  last_replayed_tli = XLogRecoveryCtl->lastReplayedTLI;

  replay_end_lsn = XLogRecoveryCtl->replayEndRecPtr;

  replay_end_tli = XLogRecoveryCtl->replayEndTLI;

  recovery_last_xact_time = XLogRecoveryCtl->recoveryLastXTime;

  current_chunk_start_time = XLogRecoveryCtl->currentChunkStartTime;

  pause_state = XLogRecoveryCtl->recoveryPauseState;

  SpinLockRelease(&XLogRecoveryCtl->info_lck);

  if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)

    elog(ERROR, "return type must be a row type");

  values = palloc0_array(Datum, tupdesc->natts);

  nulls = palloc0_array(bool, tupdesc->natts);

  values[0] = BoolGetDatum(promote_triggered);

  if (XLogRecPtrIsValid(last_replayed_read_lsn))

    values[1] = LSNGetDatum(last_replayed_read_lsn);

  else

    nulls[1] = true;

  if (XLogRecPtrIsValid(last_replayed_end_lsn))

    values[2] = LSNGetDatum(last_replayed_end_lsn);

  else

    nulls[2] = true;

  if (XLogRecPtrIsValid(last_replayed_end_lsn))

    values[3] = Int32GetDatum(last_replayed_tli);

  else

    nulls[3] = true;

  if (XLogRecPtrIsValid(replay_end_lsn))

    values[4] = LSNGetDatum(replay_end_lsn);

  else

    nulls[4] = true;

  if (XLogRecPtrIsValid(replay_end_lsn))

    values[5] = Int32GetDatum(replay_end_tli);

  else

    nulls[5] = true;

  if (recovery_last_xact_time != 0)

    values[6] = TimestampTzGetDatum(recovery_last_xact_time);

  else

    nulls[6] = true;

  if (current_chunk_start_time != 0)

    values[7] = TimestampTzGetDatum(current_chunk_start_time);

  else

    nulls[7] = true;

  values[8] = CStringGetTextDatum(GetRecoveryPauseStateString(pause_state));

  PG_RETURN_DATUM(HeapTupleGetDatum(heap_form_tuple(tupdesc, values, nulls)));

}