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Fix inadequately-tested code path in tuplesort_skiptuples(). 

Per report from Jeff Davis.
This commit is contained in:
Tom Lane 2013-12-24 17:13:02 -05:00
parent 4eeda92d86
commit 1def747db6
1 changed files with 8 additions and 1 deletions
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9
src/backend/utils/sort/tuplesort.c
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@ -1725,6 +1725,8 @@ tuplesort_getdatum(Tuplesortstate *state, bool forward,
bool bool
tuplesort_skiptuples(Tuplesortstate *state, int64 ntuples, bool forward) tuplesort_skiptuples(Tuplesortstate *state, int64 ntuples, bool forward)
{ {
MemoryContext oldcontext;
/* /*
* We don't actually support backwards skip yet, because no callers need * We don't actually support backwards skip yet, because no callers need
* it. The API is designed to allow for that later, though. * it. The API is designed to allow for that later, though.
@ -1760,6 +1762,7 @@ tuplesort_skiptuples(Tuplesortstate *state, int64 ntuples, bool forward)
* We could probably optimize these cases better, but for now it's * We could probably optimize these cases better, but for now it's
* not worth the trouble. * not worth the trouble.
*/ */
oldcontext = MemoryContextSwitchTo(state->sortcontext);
while (ntuples-- > 0) while (ntuples-- > 0)
{ {
SortTuple stup; SortTuple stup;
@ -1767,11 +1770,15 @@ tuplesort_skiptuples(Tuplesortstate *state, int64 ntuples, bool forward)
if (!tuplesort_gettuple_common(state, forward, if (!tuplesort_gettuple_common(state, forward,
&stup, &should_free)) &stup, &should_free))
{
MemoryContextSwitchTo(oldcontext);
return false; return false;
if (should_free) }
if (should_free && stup.tuple)
pfree(stup.tuple); pfree(stup.tuple);
CHECK_FOR_INTERRUPTS(); CHECK_FOR_INTERRUPTS();
} }
MemoryContextSwitchTo(oldcontext);
return true; return true;
default: default: