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Make XLogRecGetBlockTag() throw error if there's no such block. 

All but a few existing callers assume without checking that this
function succeeds.  While it probably will, that's a poor excuse for
not checking.  Let's make it return void and instead throw an error
if it doesn't find the block reference.  Callers that actually need
to handle the no-such-block case must now use the underlying function
XLogRecGetBlockTagExtended.

In addition to being a bit less error-prone, this should also serve
to suppress some Coverity complaints about XLogRecGetBlockRefInfo.

While at it, clean up some inconsistency about use of the
XLogRecHasBlockRef macro: make XLogRecGetBlockTagExtended use
that instead of open-coding the same condition, and avoid calling
XLogRecHasBlockRef twice in relevant code paths.  (That is,
calling XLogRecHasBlockRef followed by XLogRecGetBlockTag is now
deprecated: use XLogRecGetBlockTagExtended instead.)

Patch HEAD only; this doesn't seem to have enough value to consider
a back-branch API break.

Discussion: https://postgr.es/m/425039.1649701221@sss.pgh.pa.us
This commit is contained in:
Tom Lane 2022-04-11 17:43:46 -04:00
parent 9debd12348
commit bd037dc928
9 changed files with 36 additions and 23 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

2
src/backend/access/heap/heapam.c
View File

@ -9363,7 +9363,7 @@ heap_xlog_update(XLogReaderState *record, bool hot_update)
oldtup.t_len = 0;
XLogRecGetBlockTag(record, 0, &rnode, NULL, &newblk);
if (XLogRecGetBlockTag(record, 1, NULL, NULL, &oldblk))
if (XLogRecGetBlockTagExtended(record, 1, NULL, NULL, &oldblk, NULL))
{
/* HOT updates are never done across pages */
Assert(!hot_update);

2
src/backend/access/nbtree/nbtxlog.c
View File

@ -267,7 +267,7 @@ btree_xlog_split(bool newitemonleft, XLogReaderState *record)
XLogRecGetBlockTag(record, 0, NULL, NULL, &origpagenumber);
XLogRecGetBlockTag(record, 1, NULL, NULL, &rightpagenumber);
if (!XLogRecGetBlockTag(record, 2, NULL, NULL, &spagenumber))
if (!XLogRecGetBlockTagExtended(record, 2, NULL, NULL, &spagenumber, NULL))
spagenumber = P_NONE;
/*

11
src/backend/access/rmgrdesc/xlogdesc.c
View File

@ -219,15 +219,14 @@ XLogRecGetBlockRefInfo(XLogReaderState *record, bool pretty,
for (block_id = 0; block_id <= XLogRecMaxBlockId(record); block_id++)
{
RelFileNode rnode = {InvalidOid, InvalidOid, InvalidOid};
ForkNumber forknum = InvalidForkNumber;
BlockNumber blk = InvalidBlockNumber;
RelFileNode rnode;
ForkNumber forknum;
BlockNumber blk;
if (!XLogRecHasBlockRef(record, block_id))
if (!XLogRecGetBlockTagExtended(record, block_id,
&rnode, &forknum, &blk, NULL))
continue;
XLogRecGetBlockTag(record, block_id, &rnode, &forknum, &blk);
if (detailed_format)
{
/* Get block references in detailed format. */

24
src/backend/access/transam/xlogreader.c
View File

@ -37,6 +37,8 @@
#include "miscadmin.h"
#include "pgstat.h"
#include "utils/memutils.h"
#else
#include "common/logging.h"
#endif
static void report_invalid_record(XLogReaderState *state, const char *fmt,...)
@ -1918,14 +1920,25 @@ err:
/*
* Returns information about the block that a block reference refers to.
* See XLogRecGetBlockTagExtended().
*
* This is like XLogRecGetBlockTagExtended, except that the block reference
* must exist and there's no access to prefetch_buffer.
*/
bool
void
XLogRecGetBlockTag(XLogReaderState *record, uint8 block_id,
RelFileNode *rnode, ForkNumber *forknum, BlockNumber *blknum)
{
return XLogRecGetBlockTagExtended(record, block_id, rnode, forknum, blknum,
NULL);
if (!XLogRecGetBlockTagExtended(record, block_id, rnode, forknum, blknum,
NULL))
{
#ifndef FRONTEND
elog(ERROR, "failed to locate backup block with ID %d in WAL record",
block_id);
#else
pg_fatal("failed to locate backup block with ID %d in WAL record",
block_id);
#endif
}
}
/*
@ -1944,8 +1957,7 @@ XLogRecGetBlockTagExtended(XLogReaderState *record, uint8 block_id,
{
DecodedBkpBlock *bkpb;
if (block_id > record->record->max_block_id ||
!record->record->blocks[block_id].in_use)
if (!XLogRecHasBlockRef(record, block_id))
return false;
bkpb = &record->record->blocks[block_id];

7
src/backend/access/transam/xlogrecovery.c
View File

@ -2172,10 +2172,10 @@ xlog_block_info(StringInfo buf, XLogReaderState *record)
ForkNumber forknum;
BlockNumber blk;
if (!XLogRecHasBlockRef(record, block_id))
if (!XLogRecGetBlockTagExtended(record, block_id,
&rnode, &forknum, &blk, NULL))
continue;
XLogRecGetBlockTag(record, block_id, &rnode, &forknum, &blk);
if (forknum != MAIN_FORKNUM)
appendStringInfo(buf, "; blkref #%d: rel %u/%u/%u, fork %u, blk %u",
block_id,
@ -2303,7 +2303,8 @@ verifyBackupPageConsistency(XLogReaderState *record)
Buffer buf;
Page page;
if (!XLogRecGetBlockTag(record, block_id, &rnode, &forknum, &blkno))
if (!XLogRecGetBlockTagExtended(record, block_id,
&rnode, &forknum, &blkno, NULL))
{
/*
* WAL record doesn't contain a block reference with the given id.

3
src/backend/access/transam/xlogutils.c
View File

@ -369,7 +369,8 @@ XLogReadBufferForRedoExtended(XLogReaderState *record,
&prefetch_buffer))
{
/* Caller specified a bogus block_id */
elog(PANIC, "failed to locate backup block with ID %d", block_id);
elog(PANIC, "failed to locate backup block with ID %d in WAL record",
block_id);
}
/*

3
src/bin/pg_rewind/parsexlog.c
View File

@ -450,7 +450,8 @@ extractPageInfo(XLogReaderState *record)
ForkNumber forknum;
BlockNumber blkno;
if (!XLogRecGetBlockTag(record, block_id, &rnode, &forknum, &blkno))
if (!XLogRecGetBlockTagExtended(record, block_id,
&rnode, &forknum, &blkno, NULL))
continue;
/* We only care about the main fork; others are copied in toto */

5
src/bin/pg_waldump/pg_waldump.c
View File

@ -405,11 +405,10 @@ XLogRecordMatchesRelationBlock(XLogReaderState *record,
ForkNumber forknum;
BlockNumber blk;
if (!XLogRecHasBlockRef(record, block_id))
if (!XLogRecGetBlockTagExtended(record, block_id,
&rnode, &forknum, &blk, NULL))
continue;
XLogRecGetBlockTag(record, block_id, &rnode, &forknum, &blk);
if ((matchFork == InvalidForkNumber || matchFork == forknum) &&
(RelFileNodeEquals(matchRnode, emptyRelFileNode) ||
RelFileNodeEquals(matchRnode, rnode)) &&

2
src/include/access/xlogreader.h
View File

@ -429,7 +429,7 @@ extern FullTransactionId XLogRecGetFullXid(XLogReaderState *record);
extern bool RestoreBlockImage(XLogReaderState *record, uint8 block_id, char *page);
extern char *XLogRecGetBlockData(XLogReaderState *record, uint8 block_id, Size *len);
extern bool XLogRecGetBlockTag(XLogReaderState *record, uint8 block_id,
extern void XLogRecGetBlockTag(XLogReaderState *record, uint8 block_id,
RelFileNode *rnode, ForkNumber *forknum,
BlockNumber *blknum);
extern bool XLogRecGetBlockTagExtended(XLogReaderState *record, uint8 block_id,