Fix crash in json_to_record().

json_to_record() depends on get_call_result_type() for the tuple
descriptor of the record that should be returned, but in some cases
that cannot be determined. Add a guard to check if the tuple
descriptor has been properly resolved, similar to other callers of
get_call_result_type().

Also add guard for two other callers of get_call_result_type() in
jsonfuncs.c. Although json_to_record() is the only actual bug, it's a
good idea to follow convention.

diff --git a/src/backend/utils/adt/jsonfuncs.c b/src/backend/utils/adt/jsonfuncs.c
index e1d8aaed0c44c963be321f5d114db55563c927c1..232030560858f23b4403acb90e43c93e49576aba 100644 (file)
--- a/src/backend/utils/adt/jsonfuncs.c
+++ b/src/backend/utils/adt/jsonfuncs.c
@@ -941,7 +941,11 @@ each_worker(PG_FUNCTION_ARGS, bool as_text)
 
        rsi->returnMode = SFRM_Materialize;
 
-       (void) get_call_result_type(fcinfo, NULL, &tupdesc);
+       if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
+               ereport(ERROR,
+                               (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+                                errmsg("function returning record called in context "
+                                               "that cannot accept type record")));
 
        /* make these in a sufficiently long-lived memory context */
        old_cxt = MemoryContextSwitchTo(rsi->econtext->ecxt_per_query_memory);
@@ -1349,7 +1353,13 @@ populate_record_worker(PG_FUNCTION_ARGS, bool have_record_arg)
 
                json = PG_GETARG_TEXT_P(0);
 
-               get_call_result_type(fcinfo, NULL, &tupdesc);
+               if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
+                       ereport(ERROR,
+                                       (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+                                        errmsg("function returning record called in context "
+                                                       "that cannot accept type record"),
+                                        errhint("Try calling the function in the FROM clause "
+                                                        "using a column definition list.")));
        }
 
        json_hash = get_json_object_as_hash(json, "json_populate_record",
@@ -1713,7 +1723,11 @@ populate_recordset_worker(PG_FUNCTION_ARGS, bool have_record_arg)
         * get the tupdesc from the result set info - it must be a record type
         * because we already checked that arg1 is a record type.
         */
-       (void) get_call_result_type(fcinfo, NULL, &tupdesc);
+       if (get_call_result_type(fcinfo, NULL, &tupdesc) != TYPEFUNC_COMPOSITE)
+               ereport(ERROR,
+                               (errcode(ERRCODE_FEATURE_NOT_SUPPORTED),
+                                errmsg("function returning record called in context "
+                                               "that cannot accept type record")));
 
        state = palloc0(sizeof(PopulateRecordsetState));
        sem = palloc0(sizeof(JsonSemAction));