Fix volatile vs. pointer confusion

[Peter Eisentraut]

Variables used after a longjmp() need to be declared volatile.  In
case of a pointer, it's the pointer itself that needs to be declared
volatile, not the pointed-to value.  So we need

    PyObject *volatile items;

instead of

    volatile PyObject *items;  /* wrong */

Attached patch fixes a couple of cases of that.  Most instances were
already correct.

-- 
Peter Eisentraut              http://www.2ndQuadrant.com/
PostgreSQL Development, 24x7 Support, Remote DBA, Training & Services

From 1bb6acf63cf796d0659283c7ea5220385f7de181 Mon Sep 17 00:00:00 2001
From: Peter Eisentraut <pe...@eisentraut.org>
Date: Mon, 11 Mar 2019 08:18:55 +0100
Subject: [PATCH] Fix volatile vs. pointer confusion

Variables used after a longjmp() need to be declared volatile.  In
case of a pointer, it's the pointer itself that needs to be declared
volatile, not the pointed-to value.  So we need

    PyObject *volatile items;

instead of

    volatile PyObject *items;  /* wrong */
---
 contrib/hstore_plpython/hstore_plpython.c | 9 ++++-----
 contrib/jsonb_plpython/jsonb_plpython.c   | 9 +++------
 2 files changed, 7 insertions(+), 11 deletions(-)

diff --git a/contrib/hstore_plpython/hstore_plpython.c 
b/contrib/hstore_plpython/hstore_plpython.c
index 2f24090ff3..93c39d294d 100644
--- a/contrib/hstore_plpython/hstore_plpython.c
+++ b/contrib/hstore_plpython/hstore_plpython.c
@@ -128,7 +128,7 @@ Datum
 plpython_to_hstore(PG_FUNCTION_ARGS)
 {
        PyObject   *dict;
-       volatile PyObject *items_v = NULL;
+       PyObject *volatile items = NULL;
        int32           pcount;
        HStore     *out;
 
@@ -139,14 +139,13 @@ plpython_to_hstore(PG_FUNCTION_ARGS)
                                 errmsg("not a Python mapping")));
 
        pcount = PyMapping_Size(dict);
-       items_v = PyMapping_Items(dict);
+       items = PyMapping_Items(dict);
 
        PG_TRY();
        {
                int32           buflen;
                int32           i;
                Pairs      *pairs;
-               PyObject   *items = (PyObject *) items_v;
 
                pairs = palloc(pcount * sizeof(*pairs));
 
@@ -177,14 +176,14 @@ plpython_to_hstore(PG_FUNCTION_ARGS)
                                pairs[i].isnull = false;
                        }
                }
-               Py_DECREF(items_v);
+               Py_DECREF(items);
 
                pcount = hstoreUniquePairs(pairs, pcount, &buflen);
                out = hstorePairs(pairs, pcount, buflen);
        }
        PG_CATCH();
        {
-               Py_DECREF(items_v);
+               Py_DECREF(items);
                PG_RE_THROW();
        }
        PG_END_TRY();
diff --git a/contrib/jsonb_plpython/jsonb_plpython.c 
b/contrib/jsonb_plpython/jsonb_plpython.c
index f44d364c97..1bc984d5c4 100644
--- a/contrib/jsonb_plpython/jsonb_plpython.c
+++ b/contrib/jsonb_plpython/jsonb_plpython.c
@@ -237,17 +237,14 @@ PLyMapping_ToJsonbValue(PyObject *obj, JsonbParseState 
**jsonb_state)
        JsonbValue *out = NULL;
 
        /* We need it volatile, since we use it after longjmp */
-       volatile PyObject *items_v = NULL;
+       PyObject *volatile items = NULL;
 
        pcount = PyMapping_Size(obj);
-       items_v = PyMapping_Items(obj);
+       items = PyMapping_Items(obj);
 
        PG_TRY();
        {
                Py_ssize_t      i;
-               PyObject   *items;
-
-               items = (PyObject *) items_v;
 
                pushJsonbValue(jsonb_state, WJB_BEGIN_OBJECT, NULL);
 
@@ -279,7 +276,7 @@ PLyMapping_ToJsonbValue(PyObject *obj, JsonbParseState 
**jsonb_state)
        }
        PG_CATCH();
        {
-               Py_DECREF(items_v);
+               Py_DECREF(items);
                PG_RE_THROW();
        }
        PG_END_TRY();
-- 
2.21.0