Fix volatile vs. pointer confusion

petere · petere · commit c77f21899ac2 · 2019-03-15T08:38:45.000+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
@@ -124,7 +124,7 @@ Datum
 plpython_to_hstore(PG_FUNCTION_ARGS)
 {
 	PyObject   *dict;
-	volatile PyObject *items_v = NULL;
+	PyObject *volatile items = NULL;
 	int32		pcount;
 	HStore	   *out;
 
@@ -135,14 +135,13 @@ 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));
 
@@ -173,14 +172,14 @@ 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();

Original file line number	Diff line number	Diff line change
`@@ -124,7 +124,7 @@ Datum`
`124`	`124`	`plpython_to_hstore(PG_FUNCTION_ARGS)`
`125`	`125`	`{`
`126`	`126`	`PyObject *dict;`
`127`		`- volatile PyObject *items_v = NULL;`
	`127`	`+ PyObject *volatile items = NULL;`
`128`	`128`	`int32 pcount;`
`129`	`129`	`HStore *out;`
`130`	`130`
`@@ -135,14 +135,13 @@ plpython_to_hstore(PG_FUNCTION_ARGS)`
`135`	`135`	`errmsg("not a Python mapping")));`
`136`	`136`
`137`	`137`	`pcount = PyMapping_Size(dict);`
`138`		`- items_v = PyMapping_Items(dict);`
	`138`	`+ items = PyMapping_Items(dict);`
`139`	`139`
`140`	`140`	`PG_TRY();`
`141`	`141`	`{`
`142`	`142`	`int32 buflen;`
`143`	`143`	`int32 i;`
`144`	`144`	`Pairs *pairs;`
`145`		`- PyObject items = (PyObject ) items_v;`
`146`	`145`
`147`	`146`	`pairs = palloc(pcount * sizeof(*pairs));`
`148`	`147`
`@@ -173,14 +172,14 @@ plpython_to_hstore(PG_FUNCTION_ARGS)`
`173`	`172`	`pairs[i].isnull = false;`
`174`	`173`	`}`
`175`	`174`	`}`
`176`		`- Py_DECREF(items_v);`
	`175`	`+ Py_DECREF(items);`
`177`	`176`
`178`	`177`	`pcount = hstoreUniquePairs(pairs, pcount, &buflen);`
`179`	`178`	`out = hstorePairs(pairs, pcount, buflen);`
`180`	`179`	`}`
`181`	`180`	`PG_CATCH();`
`182`	`181`	`{`
`183`		`- Py_DECREF(items_v);`
	`182`	`+ Py_DECREF(items);`
`184`	`183`	`PG_RE_THROW();`
`185`	`184`	`}`
`186`	`185`	`PG_END_TRY();`