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Commit6c42b2b

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Fix unaligned accesses in DecodeUpdate().
The xl_heap_header_len structures in an XLOG_HEAP_UPDATE record aren'tnecessarily aligned adequately. The regular replay function for theserecords is aware of that, but decode.c didn't get the memo. I'm notsure why the buildfarm failed to catch this; the test_decoding testcertainly blows up real good on my old HPPA box.Also, I'm pretty sure that the address arithmetic was wrong for thecase of XLOG_HEAP_CONTAINS_OLD and not XLOG_HEAP_CONTAINS_NEW_TUPLE,though this apparently can't happen when logical decoding is active.
1 parenta3655dd commit6c42b2b

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-10
lines changed

1 file changed

+17
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‎src/backend/replication/logical/decode.c

Lines changed: 17 additions & 10 deletions
Original file line numberDiff line numberDiff line change
@@ -622,12 +622,11 @@ DecodeUpdate(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
622622
{
623623
XLogRecord*r=&buf->record;
624624
xl_heap_update*xlrec;
625-
xl_heap_header_len*xlhdr;
625+
xl_heap_header_lenxlhdr;
626626
ReorderBufferChange*change;
627627
char*data;
628628

629629
xlrec= (xl_heap_update*)buf->record_data;
630-
xlhdr= (xl_heap_header_len*) (buf->record_data+SizeOfHeapUpdate);
631630

632631
/* only interested in our database */
633632
if (xlrec->target.node.dbNode!=ctx->slot->data.database)
@@ -637,33 +636,41 @@ DecodeUpdate(LogicalDecodingContext *ctx, XLogRecordBuffer *buf)
637636
change->action=REORDER_BUFFER_CHANGE_UPDATE;
638637
memcpy(&change->data.tp.relnode,&xlrec->target.node,sizeof(RelFileNode));
639638

640-
data= (char*)&xlhdr->header;
639+
/* caution, remaining data in record is not aligned */
640+
data=buf->record_data+SizeOfHeapUpdate;
641641

642642
if (xlrec->flags&XLOG_HEAP_CONTAINS_NEW_TUPLE)
643643
{
644644
Assert(r->xl_len> (SizeOfHeapUpdate+SizeOfHeapHeaderLen));
645645

646+
memcpy(&xlhdr,data,sizeof(xlhdr));
647+
data+= offsetof(xl_heap_header_len,header);
648+
646649
change->data.tp.newtuple=ReorderBufferGetTupleBuf(ctx->reorder);
647650

648651
DecodeXLogTuple(data,
649-
xlhdr->t_len+SizeOfHeapHeader,
652+
xlhdr.t_len+SizeOfHeapHeader,
650653
change->data.tp.newtuple);
651654
/* skip over the rest of the tuple header */
652655
data+=SizeOfHeapHeader;
653656
/* skip over the tuple data */
654-
data+=xlhdr->t_len;
657+
data+=xlhdr.t_len;
655658
}
656659

657660
if (xlrec->flags&XLOG_HEAP_CONTAINS_OLD)
658661
{
659-
xlhdr= (xl_heap_header_len*)data;
662+
memcpy(&xlhdr,data,sizeof(xlhdr));
663+
data+= offsetof(xl_heap_header_len,header);
664+
660665
change->data.tp.oldtuple=ReorderBufferGetTupleBuf(ctx->reorder);
661-
DecodeXLogTuple((char*)&xlhdr->header,
662-
xlhdr->t_len+SizeOfHeapHeader,
666+
667+
DecodeXLogTuple(data,
668+
xlhdr.t_len+SizeOfHeapHeader,
663669
change->data.tp.oldtuple);
664-
data= (char*)&xlhdr->header;
670+
#ifdefNOT_USED
665671
data+=SizeOfHeapHeader;
666-
data+=xlhdr->t_len;
672+
data+=xlhdr.t_len;
673+
#endif
667674
}
668675

669676
ReorderBufferQueueChange(ctx->reorder,r->xl_xid,buf->origptr,change);

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