Fix poorly thought-through code from commit 5c3c3cd.

tglsfdc · tglsfdc · commit f73b2bbbdcb3 · 2016-04-11T00:28:44.000-04:00
It's not entirely clear to me whether PyString_AsString can return
null (looks like the answer might vary between Python 2 and 3).
But in any case, this code's attempt to cope with the possibility
was quite broken, because pstrdup() neither allows a null argument
nor ever returns a null.

Moreover, the code below this point assumes that "message" is a
palloc'd string, which would not be the case for a dgettext result.

Fix both problems by doing the pstrdup step separately.
diff --git a/src/pl/plpython/plpy_plpymodule.c b/src/pl/plpython/plpy_plpymodule.c
@@ -424,11 +424,12 @@ PLy_output(volatile int level, PyObject *self, PyObject *args, PyObject *kw)
 	else
 		so = PyObject_Str(args);
 
-	if (so == NULL || ((message = pstrdup(PyString_AsString(so))) == NULL))
+	if (so == NULL || ((message = PyString_AsString(so)) == NULL))
 	{
 		level = ERROR;
 		message = dgettext(TEXTDOMAIN, "could not parse error message in plpy.elog");
 	}
+	message = pstrdup(message);
 
 	Py_XDECREF(so);
 
@@ -444,7 +445,8 @@ PLy_output(volatile int level, PyObject *self, PyObject *args, PyObject *kw)
 				if (PyTuple_Size(args) != 0)
 					PLy_elog(ERROR, "the message is already specified");
 
-				pfree(message);
+				if (message)
+					pfree(message);
 				message = object_to_string(value);
 			}
 			else if (strcmp(keyword, "detail") == 0)

Original file line number	Diff line number	Diff line change
`@@ -424,11 +424,12 @@ PLy_output(volatile int level, PyObject self, PyObject args, PyObject *kw)`
`424`	`424`	`else`
`425`	`425`	`so = PyObject_Str(args);`
`426`	`426`
`427`		`- if (so == NULL \|\| ((message = pstrdup(PyString_AsString(so))) == NULL))`
	`427`	`+ if (so == NULL \|\| ((message = PyString_AsString(so)) == NULL))`
`428`	`428`	`{`
`429`	`429`	`level = ERROR;`
`430`	`430`	`message = dgettext(TEXTDOMAIN, "could not parse error message in plpy.elog");`
`431`	`431`	`}`
	`432`	`+ message = pstrdup(message);`
`432`	`433`
`433`	`434`	`Py_XDECREF(so);`
`434`	`435`
`@@ -444,7 +445,8 @@ PLy_output(volatile int level, PyObject self, PyObject args, PyObject *kw)`
`444`	`445`	`if (PyTuple_Size(args) != 0)`
`445`	`446`	`PLy_elog(ERROR, "the message is already specified");`
`446`	`447`
`447`		`- pfree(message);`
	`448`	`+ if (message)`
	`449`	`+ pfree(message);`
`448`	`450`	`message = object_to_string(value);`
`449`	`451`	`}`
`450`	`452`	`else if (strcmp(keyword, "detail") == 0)`