From d5f6f13f8e7eb1c28395807922246294da4f57bb Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Fri, 4 Nov 2016 13:26:49 -0400
Subject: [PATCH] Be more consistent about masking xl_info with ~XLR_INFO_MASK.
Generally, WAL resource managers are only supposed to examine the
top 4 bits of a WAL record's xl_info; the rest are reserved for
the WAL mechanism itself. A few places were not consistent about
doing this with respect to XLOG_CHECKPOINT and XLOG_SWITCH records.
There's no bug currently, since no additional bits ever get set in
these specific record types, but that might not be true forever.
Let's follow the generic coding rule here too.
Michael Paquier
---
src/backend/access/transam/xlog.c | 13 ++++++++-----
src/backend/access/transam/xlogreader.c | 3 ++-
2 files changed, 10 insertions(+), 6 deletions(-)
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index 6b1f24ef1f6..813f6467fdf 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -903,8 +903,9 @@ XLogInsertRecord(XLogRecData *rdata, XLogRecPtr fpw_lsn)
pg_crc32c rdata_crc;
bool inserted;
XLogRecord *rechdr = (XLogRecord *) rdata->data;
+ uint8 info = rechdr->xl_info & ~XLR_INFO_MASK;
bool isLogSwitch = (rechdr->xl_rmid == RM_XLOG_ID &&
- rechdr->xl_info == XLOG_SWITCH);
+ info == XLOG_SWITCH);
XLogRecPtr StartPos;
XLogRecPtr EndPos;
@@ -6170,7 +6171,7 @@ StartupXLOG(void)
if (record != NULL)
{
memcpy(&checkPoint, XLogRecGetData(xlogreader), sizeof(CheckPoint));
- wasShutdown = (record->xl_info == XLOG_CHECKPOINT_SHUTDOWN);
+ wasShutdown = ((record->xl_info & ~XLR_INFO_MASK) == XLOG_CHECKPOINT_SHUTDOWN);
ereport(DEBUG1,
(errmsg("checkpoint record is at %X/%X",
(uint32) (checkPointLoc >> 32), (uint32) checkPointLoc)));
@@ -6328,7 +6329,7 @@ StartupXLOG(void)
(errmsg("could not locate a valid checkpoint record")));
}
memcpy(&checkPoint, XLogRecGetData(xlogreader), sizeof(CheckPoint));
- wasShutdown = (record->xl_info == XLOG_CHECKPOINT_SHUTDOWN);
+ wasShutdown = ((record->xl_info & ~XLR_INFO_MASK) == XLOG_CHECKPOINT_SHUTDOWN);
}
/*
@@ -7785,6 +7786,7 @@ ReadCheckpointRecord(XLogReaderState *xlogreader, XLogRecPtr RecPtr,
int whichChkpt, bool report)
{
XLogRecord *record;
+ uint8 info;
if (!XRecOffIsValid(RecPtr))
{
@@ -7810,6 +7812,7 @@ ReadCheckpointRecord(XLogReaderState *xlogreader, XLogRecPtr RecPtr,
}
record = ReadRecord(xlogreader, RecPtr, LOG, true);
+ info = record->xl_info & ~XLR_INFO_MASK;
if (record == NULL)
{
@@ -7852,8 +7855,8 @@ ReadCheckpointRecord(XLogReaderState *xlogreader, XLogRecPtr RecPtr,
}
return NULL;
}
- if (record->xl_info != XLOG_CHECKPOINT_SHUTDOWN &&
- record->xl_info != XLOG_CHECKPOINT_ONLINE)
+ if (info != XLOG_CHECKPOINT_SHUTDOWN &&
+ info != XLOG_CHECKPOINT_ONLINE)
{
switch (whichChkpt)
{
diff --git a/src/backend/access/transam/xlogreader.c b/src/backend/access/transam/xlogreader.c
index f2da5058924..56d4c66ebbc 100644
--- a/src/backend/access/transam/xlogreader.c
+++ b/src/backend/access/transam/xlogreader.c
@@ -462,7 +462,8 @@ XLogReadRecord(XLogReaderState *state, XLogRecPtr RecPtr, char **errormsg)
/*
* Special processing if it's an XLOG SWITCH record
*/
- if (record->xl_rmid == RM_XLOG_ID && record->xl_info == XLOG_SWITCH)
+ if (record->xl_rmid == RM_XLOG_ID &&
+ (record->xl_info & ~XLR_INFO_MASK) == XLOG_SWITCH)
{
/* Pretend it extends to end of segment */
state->EndRecPtr += XLogSegSize - 1;