Fix volatile vs. pointer confusion

petere · petere · commit 1226d932b4da · 2019-03-14T08:42:48.000+01:00
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 */ Discussion: https://www.postgresql.org/message-id/flat/f747368d-9e1a-c46a-ac76-3c27da32e8e4%402ndquadrant.com
diff --git 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
@@ -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();

Original file line number	Diff line number	Diff line change
`@@ -128,7 +128,7 @@ Datum`
`128`	`128`	`plpython_to_hstore(PG_FUNCTION_ARGS)`
`129`	`129`	`{`
`130`	`130`	`PyObject *dict;`
`131`		`- volatile PyObject *items_v = NULL;`
	`131`	`+ PyObject *volatile items = NULL;`
`132`	`132`	`int32 pcount;`
`133`	`133`	`HStore *out;`
`134`	`134`
`@@ -139,14 +139,13 @@ plpython_to_hstore(PG_FUNCTION_ARGS)`
`139`	`139`	`errmsg("not a Python mapping")));`
`140`	`140`
`141`	`141`	`pcount = PyMapping_Size(dict);`
`142`		`- items_v = PyMapping_Items(dict);`
	`142`	`+ items = PyMapping_Items(dict);`
`143`	`143`
`144`	`144`	`PG_TRY();`
`145`	`145`	`{`
`146`	`146`	`int32 buflen;`
`147`	`147`	`int32 i;`
`148`	`148`	`Pairs *pairs;`
`149`		`- PyObject items = (PyObject ) items_v;`
`150`	`149`
`151`	`150`	`pairs = palloc(pcount * sizeof(*pairs));`
`152`	`151`
`@@ -177,14 +176,14 @@ plpython_to_hstore(PG_FUNCTION_ARGS)`
`177`	`176`	`pairs[i].isnull = false;`
`178`	`177`	`}`
`179`	`178`	`}`
`180`		`- Py_DECREF(items_v);`
	`179`	`+ Py_DECREF(items);`
`181`	`180`
`182`	`181`	`pcount = hstoreUniquePairs(pairs, pcount, &buflen);`
`183`	`182`	`out = hstorePairs(pairs, pcount, buflen);`
`184`	`183`	`}`
`185`	`184`	`PG_CATCH();`
`186`	`185`	`{`
`187`		`- Py_DECREF(items_v);`
	`186`	`+ Py_DECREF(items);`
`188`	`187`	`PG_RE_THROW();`
`189`	`188`	`}`
`190`	`189`	`PG_END_TRY();`
Original file line number	Diff line number	Diff line change
`@@ -237,17 +237,14 @@ PLyMapping_ToJsonbValue(PyObject obj, JsonbParseState *jsonb_state)`
`237`	`237`	`JsonbValue *out = NULL;`
`238`	`238`
`239`	`239`	`/* We need it volatile, since we use it after longjmp */`
`240`		`- volatile PyObject *items_v = NULL;`
	`240`	`+ PyObject *volatile items = NULL;`
`241`	`241`
`242`	`242`	`pcount = PyMapping_Size(obj);`
`243`		`- items_v = PyMapping_Items(obj);`
	`243`	`+ items = PyMapping_Items(obj);`
`244`	`244`
`245`	`245`	`PG_TRY();`
`246`	`246`	`{`
`247`	`247`	`Py_ssize_t i;`
`248`		`- PyObject *items;`
`249`		`-`
`250`		`- items = (PyObject *) items_v;`
`251`	`248`
`252`	`249`	`pushJsonbValue(jsonb_state, WJB_BEGIN_OBJECT, NULL);`
`253`	`250`
`@@ -279,7 +276,7 @@ PLyMapping_ToJsonbValue(PyObject obj, JsonbParseState *jsonb_state)`
`279`	`276`	`}`
`280`	`277`	`PG_CATCH();`
`281`	`278`	`{`
`282`		`- Py_DECREF(items_v);`
	`279`	`+ Py_DECREF(items);`
`283`	`280`	`PG_RE_THROW();`
`284`	`281`	`}`
`285`	`282`	`PG_END_TRY();`