2010-04-08 Phil Muldoon <pmuldoon@redhat.com>

	PR python/11417

	* python/py-lazy-string.c (stpy_convert_to_value): Check for
          a NULL address.
	  (gdbpy_create_lazy_string_object): Allow strings with a NULL
          address and a zero length.

2010-04-08  Phil Muldoon  <pmuldoon@redhat.com>

	* gdb.python/py-value: Add null string variable.
	  (test_lazy_string): Test zero length, NULL address lazy
	  strings.

1 files changed, 10 insertions, 2 deletions

diff --git a/gdb/python/py-lazy-string.c b/gdb/python/py-lazy-string.c
index 8309527..a2faa0e 100644
--- a/gdb/python/py-lazy-string.c
+++ b/gdb/python/py-lazy-string.c
@@ -94,6 +94,13 @@ stpy_convert_to_value  (PyObject *self, PyObject *args)
   lazy_string_object *self_string = (lazy_string_object *) self;
   struct value *val;
 
+  if (self_string->address == 0)
+    {
+      PyErr_SetString (PyExc_MemoryError,
+		       "Cannot create a value from NULL");
+      return NULL;
+    }
+
   val = value_at_lazy (self_string->type, self_string->address);
   return value_to_value_object (val);
 }
@@ -111,10 +118,11 @@ gdbpy_create_lazy_string_object (CORE_ADDR address, long length,
 {
   lazy_string_object *str_obj = NULL;
 
-  if (address == 0)
+  if (address == 0 && length != 0)
     {
       PyErr_SetString (PyExc_MemoryError,
-		       "Cannot create a lazy string from a GDB-side string.");
+		       _("Cannot create a lazy string with address 0x0, " \
+			 "and a non-zero length."));
       return NULL;
     }