[pypy-commit] cffi default: Test and fix: it's inconvenient that str(x) crashes with a segfault

[arigo]

Author: Armin Rigo <arigo at tunes.org>
Branch: 
Changeset: r521:68ad27bb619c
Date: 2012-06-26 11:12 +0200
http://bitbucket.org/cffi/cffi/changeset/68ad27bb619c/

Log:	Test and fix: it's inconvenient that str(x) crashes with a segfault
	if x is <cdata 'char *' NULL>. Detect this case and raise
	RuntimeError.

diff --git a/c/_ffi_backend.c b/c/_ffi_backend.c
--- a/c/_ffi_backend.c
+++ b/c/_ffi_backend.c
@@ -1063,8 +1063,19 @@
             if (end != NULL)
                 length = end - start;
         }
-        else
+        else {
+            if (cd->c_data == NULL) {
+                PyObject *s = cdata_repr(cd);
+                if (s != NULL) {
+                    PyErr_Format(PyExc_RuntimeError,
+                                 "cannot use str() on %s",
+                                 PyString_AS_STRING(s));
+                    Py_DECREF(s);
+                }
+                return NULL;
+            }
             length = strlen(cd->c_data);
+        }
 
         return PyString_FromStringAndSize(cd->c_data, length);
     }
diff --git a/c/test_c.py b/c/test_c.py
--- a/c/test_c.py
+++ b/c/test_c.py
@@ -1075,6 +1075,7 @@
     assert str(a) == "hello"
     p = a + 2
     assert str(p) == "llo"
+    py.test.raises(RuntimeError, str, cast(BCharP, 0))
 
 def test_bug_convert_to_ptr():
     BChar = new_primitive_type("char")