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When targetlist is NULL, ExecTargetList was passing back a

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pointer to palloc'd but uninitialized memory.  This is not cool; anyone looking
at the returned 'tuple' would at best coredump and at worst behave in a
bizarre and irreproducible way.  Fix it to return a predictable value,
namely a correctly-set-up palloc'd tuple containing zero attributes.
I believe this fix is both safe and critical.
This commit is contained in:
Tom Lane 1999-06-12 19:22:40 +00:00
parent 0c3281ce7c
commit 1918a1d191
1 changed files with 10 additions and 32 deletions
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42
src/backend/executor/execQual.c
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@ -7,7 +7,7 @@
*
*
* IDENTIFICATION
* $Header: /cvsroot/pgsql/src/backend/executor/execQual.c,v 1.52 1999/05/25 22:40:59 momjian Exp $
* $Header: /cvsroot/pgsql/src/backend/executor/execQual.c,v 1.53 1999/06/12 19:22:40 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -1432,6 +1432,7 @@ ExecTargetList(List *targetlist,
Datum constvalue;
HeapTuple newTuple;
bool isNull;
static struct tupleDesc NullTupleDesc; /* we assume this inits to zeroes */
/*
* debugging stuff
@ -1441,35 +1442,15 @@ ExecTargetList(List *targetlist,
EV_printf("\n");
/*
* Return a dummy tuple if the targetlist is empty. the dummy tuple is
* necessary to differentiate between passing and failing the
* qualification.
* There used to be some klugy and demonstrably broken code here that
* special-cased the situation where targetlist == NIL. Now we just
* fall through and return an empty-but-valid tuple. We do, however,
* have to cope with the possibility that targettype is NULL ---
* heap_formtuple won't like that, so pass a dummy descriptor with
* natts = 0 to deal with it.
*/
if (targetlist == NIL)
{
/*
* I now think that the only time this makes any sense is when we
* run a delete query. Then we need to return something other
* than nil so we know to delete the tuple associated with the
* saved tupleid.. see what ExecutePlan does with the returned
* tuple.. -cim 9/21/89
*
* It could also happen in queries like: retrieve (foo.all) where
* bar.a = 3
*
* is this a new phenomenon? it might cause bogus behavior if we try
* to free this tuple later!! I put a hook in ExecProject to watch
* out for this case -mer 24 Aug 1992
*
* We must return dummy tuple!!! Try select t1.x from t1, t2 where
* t1.y = 1 and t2.y = 1 - t2 scan target list will be empty and
* so no one tuple will be returned! But Mer was right - dummy
* tuple must be palloced... - vadim 03/01/1999
*/
*isDone = true;
return (HeapTuple) palloc(1);
}
if (targettype == NULL)
targettype = &NullTupleDesc;
/*
* allocate an array of char's to hold the "null" information only if
@ -1645,9 +1626,6 @@ ExecProject(ProjectionInfo *projInfo, bool *isDone)
/*
* store the tuple in the projection slot and return the slot.
*
* If there's no projection target list we don't want to pfree the bogus
* tuple that ExecTargetList passes back to us. -mer 24 Aug 1992
*/
return (TupleTableSlot *)
ExecStoreTuple(newTuple,/* tuple to store */