Re: [PATCH v1] gdb/python: fix memory leak in gdb_py_tp_name

[Matthieu Longo <matthieu.longo@arm.com>]

On 28/05/2026 20:00, Tom Tromey wrote:
>>>>>> "Matthieu" == Matthieu Longo <matthieu.longo@arm.com> writes:
> 
> Matthieu> Indeed that can happen, for instance, when this function is called
> Matthieu> inside a tp_clear() in the middle of a PyObject destruction.
> 
> Thanks.
> 
> Matthieu> Something like below would at least avoid the general abort, but it
> Matthieu> would cause logging of errors in the middle of the destruction. How
> Matthieu> useful would it be ?
> 
> Matthieu> gdbpy_ref<> fully_qualified_name (PyType_GetFullyQualifiedName (py_type));
> Matthieu> if (fully_qualified_name == nullptr)
> Matthieu>   {
> Matthieu>     PyErr_Print();
> Matthieu>     PyErr_Clear();
> Matthieu>     return {};
> Matthieu>   }
> 
> Matthieu> At this point, I don't think that it is super important not to crash
> Matthieu> because there is a serious logic error somewhere if we are unable to
> Matthieu> get this name. Consequently, an assert might be more appropriate.
> 
> If we think it could conceivably happen then it should probably just
> call gdbpy_print_stack (which is basically the above but with some user
> controls) and then return some error string.
> 
> Tom

What about the below ?

Matthieu

diff --git a/gdb/python/py-obj-type.c b/gdb/python/py-obj-type.c
index 45f7d8a3d74..514dbf5c179 100644
--- a/gdb/python/py-obj-type.c
+++ b/gdb/python/py-obj-type.c
@@ -27,7 +27,11 @@ gdb_py_tp_name (PyTypeObject *py_type) noexcept
    auto pyobj_to_str = [](PyObject *name) -> std::string
    {
      const char *s = PyUnicode_AsUTF8AndSize (name, nullptr);
-    return (s == nullptr) ? "" : s;
+    if (s != nullptr)
+      return s;
+
+    gdbpy_print_stack ();
+    error (_("Could not convert PyObject to UTF-8 string."));
    };

  #if PY_VERSION_HEX >= 0x030d0000
@@ -35,8 +39,10 @@ gdb_py_tp_name (PyTypeObject *py_type) noexcept
       part of the stable ABI since version 3.13.  */
    gdbpy_ref<> fully_qualified_name (PyType_GetFullyQualifiedName (py_type));
    if (fully_qualified_name == nullptr)
-    return {};
-
+    {
+      gdbpy_print_stack ();
+      error (_("Could not get fully qualified name."));
+    }
    return pyobj_to_str (fully_qualified_name.get ());

  #else /* PY_VERSION_HEX < 0x030d0000 && ! defined (Py_LIMITED_API)  */
@@ -52,8 +58,10 @@ gdb_py_tp_name (PyTypeObject *py_type) noexcept
    /* Note: PyType_GetQualName() was added in version 3.11.  */
    gdbpy_ref<> qualname (PyType_GetQualName (py_type));
    if (qualname == nullptr)
-    return {};
-
+    {
+      gdbpy_print_stack ();
+      error (_("Could not get qualified name."));
+    }
    return pyobj_to_str (qualname.get ());

  # else
@@ -64,8 +72,10 @@ gdb_py_tp_name (PyTypeObject *py_type) noexcept
       when the minimum supported Python version is increased above 3.10.  */
    PyHeapTypeObject *ht = (PyHeapTypeObject *) py_type;
    if (ht->ht_qualname == nullptr)
-    return {};
-
+    {
+      gdbpy_print_stack ();
+      error (_("Could not get qualified name."));
+    }
    return pyobj_to_str (ht->ht_qualname);
  # endif
  #endif