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Track nesting depth correctly when drilling down into RECORD Vars.

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expandRecordVariable() failed to adjust the parse nesting structure
correctly when recursing to inspect an outer-level Var.  This could
result in assertion failures or core dumps in corner cases.

Likewise, get_name_for_var_field() failed to adjust the deparse
namespace stack correctly when recursing to inspect an outer-level
Var.  In this case the likely result was a "bogus varno" error
while deparsing a view.

Per bug #18077 from Jingzhou Fu.  Back-patch to all supported
branches.

Richard Guo, with some adjustments by me

Discussion: https://postgr.es/m/18077-b9db97c6e0ab45d8@postgresql.org
This commit is contained in:
Tom Lane
2023-09-15 17:01:26 -04:00
parent a396e20ad0
commit e0e492e5a9
4 changed files with 121 additions and 22 deletions
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17
src/backend/parser/parse_target.c
View File

@@ -1499,7 +1499,8 @@ ExpandRowReference(ParseState *pstate, Node *expr,
* drill down to find the ultimate defining expression and attempt to infer
* the tupdesc from it. We ereport if we can't determine the tupdesc.
*
* levelsup is an extra offset to interpret the Var's varlevelsup correctly.
* levelsup is an extra offset to interpret the Var's varlevelsup correctly
* when recursing. Outside callers should pass zero.
*/
TupleDesc
expandRecordVariable(ParseState *pstate, Var *var, int levelsup)
@@ -1587,10 +1588,17 @@ expandRecordVariable(ParseState *pstate, Var *var, int levelsup)
/*
* Recurse into the sub-select to see what its Var refers
* to. We have to build an additional level of ParseState
* to keep in step with varlevelsup in the subselect.
* to keep in step with varlevelsup in the subselect;
* furthermore, the subquery RTE might be from an outer
* query level, in which case the ParseState for the
* subselect must have that outer level as parent.
*/
ParseState mypstate = {0};
Index levelsup;
/* this loop must work, since GetRTEByRangeTablePosn did */
for (levelsup = 0; levelsup < netlevelsup; levelsup++)
pstate = pstate->parentParseState;
mypstate.parentParseState = pstate;
mypstate.p_rtable = rte->subquery->rtable;
/* don't bother filling the rest of the fake pstate */
@@ -1641,12 +1649,11 @@ expandRecordVariable(ParseState *pstate, Var *var, int levelsup)
* Recurse into the CTE to see what its Var refers to. We
* have to build an additional level of ParseState to keep
* in step with varlevelsup in the CTE; furthermore it
* could be an outer CTE.
* could be an outer CTE (compare SUBQUERY case above).
*/
ParseState mypstate;
ParseState mypstate = {0};
Index levelsup;
MemSet(&mypstate, 0, sizeof(mypstate));
/* this loop must work, since GetCTEForRTE did */
for (levelsup = 0;
levelsup < rte->ctelevelsup + netlevelsup;

41
src/backend/utils/adt/ruleutils.c
View File

@@ -7820,22 +7820,28 @@ get_name_for_var_field(Var *var, int fieldno,
* Recurse into the sub-select to see what its Var
* refers to. We have to build an additional level of
* namespace to keep in step with varlevelsup in the
* subselect.
* subselect; furthermore, the subquery RTE might be
* from an outer query level, in which case the
* namespace for the subselect must have that outer
* level as parent namespace.
*/
List *save_nslist = context->namespaces;
List *parent_namespaces;
deparse_namespace mydpns;
const char *result;
set_deparse_for_query(&mydpns, rte->subquery,
context->namespaces);
parent_namespaces = list_copy_tail(context->namespaces,
netlevelsup);
context->namespaces = lcons(&mydpns,
context->namespaces);
set_deparse_for_query(&mydpns, rte->subquery,
parent_namespaces);
context->namespaces = lcons(&mydpns, parent_namespaces);
result = get_name_for_var_field((Var *) expr, fieldno,
0, context);
context->namespaces =
list_delete_first(context->namespaces);
context->namespaces = save_nslist;
return result;
}
@@ -7927,7 +7933,7 @@ get_name_for_var_field(Var *var, int fieldno,
attnum);
if (ste == NULL || ste->resjunk)
elog(ERROR, "subquery %s does not have attribute %d",
elog(ERROR, "CTE %s does not have attribute %d",
rte->eref->aliasname, attnum);
expr = (Node *) ste->expr;
if (IsA(expr, Var))
@@ -7935,21 +7941,22 @@ get_name_for_var_field(Var *var, int fieldno,
/*
* Recurse into the CTE to see what its Var refers to.
* We have to build an additional level of namespace
* to keep in step with varlevelsup in the CTE.
* Furthermore it could be an outer CTE, so we may
* have to delete some levels of namespace.
* to keep in step with varlevelsup in the CTE;
* furthermore it could be an outer CTE (compare
* SUBQUERY case above).
*/
List *save_nslist = context->namespaces;
List *new_nslist;
List *parent_namespaces;
deparse_namespace mydpns;
const char *result;
set_deparse_for_query(&mydpns, ctequery,
context->namespaces);
parent_namespaces = list_copy_tail(context->namespaces,
ctelevelsup);
new_nslist = list_copy_tail(context->namespaces,
ctelevelsup);
context->namespaces = lcons(&mydpns, new_nslist);
set_deparse_for_query(&mydpns, ctequery,
parent_namespaces);
context->namespaces = lcons(&mydpns, parent_namespaces);
result = get_name_for_var_field((Var *) expr, fieldno,
0, context);