diff options
Diffstat (limited to 'src/backend/executor/execQual.c')
| -rw-r--r-- | src/backend/executor/execQual.c | 22 |
1 files changed, 17 insertions, 5 deletions
diff --git a/src/backend/executor/execQual.c b/src/backend/executor/execQual.c index ea8850e12cf..bd68554a933 100644 --- a/src/backend/executor/execQual.c +++ b/src/backend/executor/execQual.c @@ -2889,19 +2889,30 @@ ExecEvalCase(CaseExprState *caseExpr, ExprContext *econtext, /* * If there's a test expression, we have to evaluate it and save the value - * where the CaseTestExpr placeholders can find it. We must save and + * where the CaseTestExpr placeholders can find it. We must save and * restore prior setting of econtext's caseValue fields, in case this node - * is itself within a larger CASE. + * is itself within a larger CASE. Furthermore, don't assign to the + * econtext fields until after returning from evaluation of the test + * expression. We used to pass &econtext->caseValue_isNull to the + * recursive call, but that leads to aliasing that variable within said + * call, which can (and did) produce bugs when the test expression itself + * contains a CASE. + * + * If there's no test expression, we don't actually need to save and + * restore these fields; but it's less code to just do so unconditionally. */ save_datum = econtext->caseValue_datum; save_isNull = econtext->caseValue_isNull; if (caseExpr->arg) { + bool arg_isNull; + econtext->caseValue_datum = ExecEvalExpr(caseExpr->arg, econtext, - &econtext->caseValue_isNull, + &arg_isNull, NULL); + econtext->caseValue_isNull = arg_isNull; } /* @@ -2913,10 +2924,11 @@ ExecEvalCase(CaseExprState *caseExpr, ExprContext *econtext, { CaseWhenState *wclause = lfirst(clause); Datum clause_value; + bool clause_isNull; clause_value = ExecEvalExpr(wclause->expr, econtext, - isNull, + &clause_isNull, NULL); /* @@ -2924,7 +2936,7 @@ ExecEvalCase(CaseExprState *caseExpr, ExprContext *econtext, * statement is satisfied. A NULL result from the test is not * considered true. */ - if (DatumGetBool(clause_value) && !*isNull) + if (DatumGetBool(clause_value) && !clause_isNull) { econtext->caseValue_datum = save_datum; econtext->caseValue_isNull = save_isNull; |