[Python-Dev] PEP 393 review

[Stefan Behnel]

Stefan Behnel, 25.08.2011 23:30:
> Sadly, a quick look at a couple of recent commits in the pep-393 branch
> suggested that it is not even always obvious to you as the authors which
> macros can be called safely and which cannot. I immediately spotted a bug
> in one of the updated core functions (unicode_repr, IIRC) where
> PyUnicode_GET_LENGTH() is called without a previous call to
> PyUnicode_FAST_READY().

Here is another example from unicodeobject.c, commit 56aaa17fc05e:

+    switch(PyUnicode_KIND(string)) {
+    case PyUnicode_1BYTE_KIND:
+        list = ucs1lib_splitlines(
+            (PyObject*) string, PyUnicode_1BYTE_DATA(string),
+            PyUnicode_GET_LENGTH(string), keepends);
+        break;
+    case PyUnicode_2BYTE_KIND:
+        list = ucs2lib_splitlines(
+            (PyObject*) string, PyUnicode_2BYTE_DATA(string),
+            PyUnicode_GET_LENGTH(string), keepends);
+        break;
+    case PyUnicode_4BYTE_KIND:
+        list = ucs4lib_splitlines(
+            (PyObject*) string, PyUnicode_4BYTE_DATA(string),
+            PyUnicode_GET_LENGTH(string), keepends);
+        break;
+    default:
+        assert(0);
+        list = 0;
+    }

The assert(0) at the end will hit when the system is running out of memory 
while working on a wchar string.

Stefan