Fix for bug 133489: compiler leaks memory
Two different but related problems:
1. PySymtable_Free() must explicitly DECREF(st->st_cur), which should
always point to the global symtable entry. This entry is setup by the
first enter_scope() call, but there is never a corresponding
exit_scope() call.
Since each entry has a reference to scopes defined within it, the
missing DECREF caused all symtable entries to be leaked.
2. The leak here masked a separate problem with
PySymtableEntry_New(). When the requested entry was found in
st->st_symbols, the entry was returned without doing an INCREF.
And problem c) The ste_children slot was getting two copies of each
child entry, because it was populating the slot on the first and
second passes. Now only populate on the first pass.
diff --git a/Python/compile.c b/Python/compile.c
index f2d424b..7eac91a 100644
--- a/Python/compile.c
+++ b/Python/compile.c
@@ -3912,8 +3912,10 @@
PyErr_SetString(PyExc_SystemError, "lost syntax error");
}
exit:
- if (base == NULL)
+ if (base == NULL) {
PySymtable_Free(sc.c_symtable);
+ sc.c_symtable = NULL;
+ }
com_free(&sc);
return co;
}
@@ -4193,6 +4195,7 @@
{
Py_XDECREF(st->st_symbols);
Py_XDECREF(st->st_stack);
+ Py_XDECREF(st->st_cur);
PyMem_Free((void *)st);
}
@@ -4359,10 +4362,11 @@
PySymtableEntry_New(st, name, type, lineno);
if (strcmp(name, TOP) == 0)
st->st_global = st->st_cur->ste_symbols;
- if (prev)
+ if (prev && st->st_pass == 1) {
if (PyList_Append(prev->ste_children,
(PyObject *)st->st_cur) < 0)
st->st_errors++;
+ }
}
static int
diff --git a/Python/symtable.c b/Python/symtable.c
index 5dc0272..0d2e324 100644
--- a/Python/symtable.c
+++ b/Python/symtable.c
@@ -13,8 +13,10 @@
if (k == NULL)
goto fail;
v = PyDict_GetItem(st->st_symbols, k);
- if (v) /* XXX could check that name, type, lineno match */
- return v;
+ if (v) /* XXX could check that name, type, lineno match */ {
+ Py_INCREF(v);
+ return v;
+ }
ste = (PySymtableEntryObject *)PyObject_New(PySymtableEntryObject,
&PySymtableEntry_Type);
@@ -69,7 +71,7 @@
if (PyDict_SetItem(st->st_symbols, ste->ste_id, (PyObject *)ste) < 0)
goto fail;
-
+
return (PyObject *)ste;
fail:
Py_XDECREF(ste);