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postgres/src/backend/utils/misc/pg_controldata.c
Thomas Munro c558e6fd92 Acquire ControlFileLock in relevant SQL functions. 
Commit dc7d70ea added functions that read the control file, but didn't
acquire ControlFileLock.  With unlucky timing, file systems that have
weak interlocking like ext4 and ntfs could expose partially overwritten
contents, and the checksum would fail.

Back-patch to all supported releases.

Reviewed-by: David Steele <david@pgmasters.net>
Reviewed-by: Anton A. Melnikov <aamelnikov@inbox.ru>
Reviewed-by: Michael Paquier <michael@paquier.xyz>
Discussion: https://postgr.es/m/20221123014224.xisi44byq3cf5psi%40awork3.anarazel.de
2023-10-16 10:43:47 +13:00

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/*-------------------------------------------------------------------------
*
* pg_controldata.c
*
* Routines to expose the contents of the control data file via
* a set of SQL functions.
*
* Portions Copyright (c) 1996-2023, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* IDENTIFICATION
* src/backend/utils/misc/pg_controldata.c
*-------------------------------------------------------------------------
*/
#include "postgres.h"
#include "access/htup_details.h"
#include "access/transam.h"
#include "access/xlog.h"
#include "access/xlog_internal.h"
#include "catalog/pg_control.h"
#include "catalog/pg_type.h"
#include "common/controldata_utils.h"
#include "funcapi.h"
#include "miscadmin.h"
#include "storage/lwlock.h"
#include "utils/builtins.h"
#include "utils/pg_lsn.h"
#include "utils/timestamp.h"
Datum
pg_control_system(PG_FUNCTION_ARGS)
{
Datum values[4];
bool nulls[4];
TupleDesc tupdesc;
HeapTuple htup;
ControlFileData *ControlFile;
bool crc_ok;
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
/* read the control file */
LWLockAcquire(ControlFileLock, LW_SHARED);
ControlFile = get_controlfile(DataDir, &crc_ok);
LWLockRelease(ControlFileLock);
if (!crc_ok)
ereport(ERROR,
(errmsg("calculated CRC checksum does not match value stored in file")));
values[0] = Int32GetDatum(ControlFile->pg_control_version);
nulls[0] = false;
values[1] = Int32GetDatum(ControlFile->catalog_version_no);
nulls[1] = false;
values[2] = Int64GetDatum(ControlFile->system_identifier);
nulls[2] = false;
values[3] = TimestampTzGetDatum(time_t_to_timestamptz(ControlFile->time));
nulls[3] = false;
htup = heap_form_tuple(tupdesc, values, nulls);
PG_RETURN_DATUM(HeapTupleGetDatum(htup));
}
Datum
pg_control_checkpoint(PG_FUNCTION_ARGS)
{
Datum values[18];
bool nulls[18];
TupleDesc tupdesc;
HeapTuple htup;
ControlFileData *ControlFile;
XLogSegNo segno;
char xlogfilename[MAXFNAMELEN];
bool crc_ok;
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
/* Read the control file. */
LWLockAcquire(ControlFileLock, LW_SHARED);
ControlFile = get_controlfile(DataDir, &crc_ok);
LWLockRelease(ControlFileLock);
if (!crc_ok)
ereport(ERROR,
(errmsg("calculated CRC checksum does not match value stored in file")));
/*
* Calculate name of the WAL file containing the latest checkpoint's REDO
* start point.
*/
XLByteToSeg(ControlFile->checkPointCopy.redo, segno, wal_segment_size);
XLogFileName(xlogfilename, ControlFile->checkPointCopy.ThisTimeLineID,
segno, wal_segment_size);
/* Populate the values and null arrays */
values[0] = LSNGetDatum(ControlFile->checkPoint);
nulls[0] = false;
values[1] = LSNGetDatum(ControlFile->checkPointCopy.redo);
nulls[1] = false;
values[2] = CStringGetTextDatum(xlogfilename);
nulls[2] = false;
values[3] = Int32GetDatum(ControlFile->checkPointCopy.ThisTimeLineID);
nulls[3] = false;
values[4] = Int32GetDatum(ControlFile->checkPointCopy.PrevTimeLineID);
nulls[4] = false;
values[5] = BoolGetDatum(ControlFile->checkPointCopy.fullPageWrites);
nulls[5] = false;
values[6] = CStringGetTextDatum(psprintf("%u:%u",
EpochFromFullTransactionId(ControlFile->checkPointCopy.nextXid),
XidFromFullTransactionId(ControlFile->checkPointCopy.nextXid)));
nulls[6] = false;
values[7] = ObjectIdGetDatum(ControlFile->checkPointCopy.nextOid);
nulls[7] = false;
values[8] = TransactionIdGetDatum(ControlFile->checkPointCopy.nextMulti);
nulls[8] = false;
values[9] = TransactionIdGetDatum(ControlFile->checkPointCopy.nextMultiOffset);
nulls[9] = false;
values[10] = TransactionIdGetDatum(ControlFile->checkPointCopy.oldestXid);
nulls[10] = false;
values[11] = ObjectIdGetDatum(ControlFile->checkPointCopy.oldestXidDB);
nulls[11] = false;
values[12] = TransactionIdGetDatum(ControlFile->checkPointCopy.oldestActiveXid);
nulls[12] = false;
values[13] = TransactionIdGetDatum(ControlFile->checkPointCopy.oldestMulti);
nulls[13] = false;
values[14] = ObjectIdGetDatum(ControlFile->checkPointCopy.oldestMultiDB);
nulls[14] = false;
values[15] = TransactionIdGetDatum(ControlFile->checkPointCopy.oldestCommitTsXid);
nulls[15] = false;
values[16] = TransactionIdGetDatum(ControlFile->checkPointCopy.newestCommitTsXid);
nulls[16] = false;
values[17] = TimestampTzGetDatum(time_t_to_timestamptz(ControlFile->checkPointCopy.time));
nulls[17] = false;
htup = heap_form_tuple(tupdesc, values, nulls);
PG_RETURN_DATUM(HeapTupleGetDatum(htup));
}
Datum
pg_control_recovery(PG_FUNCTION_ARGS)
{
Datum values[5];
bool nulls[5];
TupleDesc tupdesc;
HeapTuple htup;
ControlFileData *ControlFile;
bool crc_ok;
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
/* read the control file */
LWLockAcquire(ControlFileLock, LW_SHARED);
ControlFile = get_controlfile(DataDir, &crc_ok);
LWLockRelease(ControlFileLock);
if (!crc_ok)
ereport(ERROR,
(errmsg("calculated CRC checksum does not match value stored in file")));
values[0] = LSNGetDatum(ControlFile->minRecoveryPoint);
nulls[0] = false;
values[1] = Int32GetDatum(ControlFile->minRecoveryPointTLI);
nulls[1] = false;
values[2] = LSNGetDatum(ControlFile->backupStartPoint);
nulls[2] = false;
values[3] = LSNGetDatum(ControlFile->backupEndPoint);
nulls[3] = false;
values[4] = BoolGetDatum(ControlFile->backupEndRequired);
nulls[4] = false;
htup = heap_form_tuple(tupdesc, values, nulls);
PG_RETURN_DATUM(HeapTupleGetDatum(htup));
}
Datum
pg_control_init(PG_FUNCTION_ARGS)
{
Datum values[11];
bool nulls[11];
TupleDesc tupdesc;
HeapTuple htup;
ControlFileData *ControlFile;
bool crc_ok;
if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
elog(ERROR, "return type must be a row type");
/* read the control file */
LWLockAcquire(ControlFileLock, LW_SHARED);
ControlFile = get_controlfile(DataDir, &crc_ok);
LWLockRelease(ControlFileLock);
if (!crc_ok)
ereport(ERROR,
(errmsg("calculated CRC checksum does not match value stored in file")));
values[0] = Int32GetDatum(ControlFile->maxAlign);
nulls[0] = false;
values[1] = Int32GetDatum(ControlFile->blcksz);
nulls[1] = false;
values[2] = Int32GetDatum(ControlFile->relseg_size);
nulls[2] = false;
values[3] = Int32GetDatum(ControlFile->xlog_blcksz);
nulls[3] = false;
values[4] = Int32GetDatum(ControlFile->xlog_seg_size);
nulls[4] = false;
values[5] = Int32GetDatum(ControlFile->nameDataLen);
nulls[5] = false;
values[6] = Int32GetDatum(ControlFile->indexMaxKeys);
nulls[6] = false;
values[7] = Int32GetDatum(ControlFile->toast_max_chunk_size);
nulls[7] = false;
values[8] = Int32GetDatum(ControlFile->loblksize);
nulls[8] = false;
values[9] = BoolGetDatum(ControlFile->float8ByVal);
nulls[9] = false;
values[10] = Int32GetDatum(ControlFile->data_checksum_version);
nulls[10] = false;
htup = heap_form_tuple(tupdesc, values, nulls);
PG_RETURN_DATUM(HeapTupleGetDatum(htup));
}
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