gdb/py-target: Make the code compile against python3

* This is a first step in supporting python3 version.
Most of the changes cope with the fact that there is no longer a
PyString_* object. Instead there is either PyUnicode or PyBytes. In order to
obtain a char* one must first convert the PyUnicode object to PyBytes,
representing a byte array. And then get a pointer to the byte array.

* Another thing is that there is no longer a PyInt. Everything is PyLong, so
comment out a PyInt check in register_set_value.

(cherry picked from commit 6c1337293ad98d6178b3d6c2f21edbe74e967e22)

Author: lorddoskias

gdb/python/py-block.c

@@ -147,8 +147,7 @@ PyObject* DictIter_iternext(PyObject *self)
 }
 
 static PyTypeObject DictIterType = {
-PyObject_HEAD_INIT(NULL)
-0,                         /*ob_size*/
+PyVarObject_HEAD_INIT (NULL, 0)
 "gdb._DictIter",            /*tp_name*/
 sizeof(DictIter),       /*tp_basicsize*/
 0,                         /*tp_itemsize*/

gdb/python/py-minsymbol.c

@@ -319,23 +319,43 @@ gdbpy_lookup_minimal_symbol (PyObject *self, PyObject *args, PyObject *kw)
   static char *keywords[] = { "name", "sfile", "objfile", NULL };
   struct bound_minimal_symbol bound_minsym = {};
   PyObject *msym_obj = NULL, *sfile_obj = NULL, *objfile_obj = NULL;
+#if PY_MAJOR_VERSION >= 3
+  PyObject *temp = NULL;
+#endif
 
   if (!PyArg_ParseTupleAndKeywords (args, kw, "s|OO", keywords, &name,
 				    &sfile_obj, &objfile_obj))
     return NULL;
 
   if (sfile_obj && sfile_obj != Py_None)
     {
-      sfile = PyString_AsString (sfile_obj);
-      if (!sfile)
-	return NULL;
+#if PY_MAJOR_VERSION >= 3
+	  temp = PyUnicode_AsASCIIString(sfile_obj);
+	  if (!temp)
+		  return NULL;
+
+      sfile = PyBytes_AsString(temp); 
+#else
+	  sfile = PyString_AsString(sfile_obj);
+#endif
+
+      if (!sfile) {
+#if PY_MAJOR_VERSION >= 3
+		Py_DECREF(temp); 
+#endif
+		return NULL;
+	  }
     }
 
   if (objfile_obj && objfile_obj != Py_None)
     {
       objfile = objfpy_object_to_objfile (objfile_obj);
-      if (!objfile)
-	return NULL;
+      if (!objfile) {
+#if PY_MAJOR_VERSION >= 3
+		Py_DECREF(temp);
+#endif
+		return NULL;
+	  }
     }
 
   TRY
@@ -348,6 +368,10 @@ gdbpy_lookup_minimal_symbol (PyObject *self, PyObject *args, PyObject *kw)
     }
   END_CATCH
 
+#if PY_MAJOR_VERSION >= 3
+  Py_XDECREF(temp);
+#endif
+
   if (bound_minsym.minsym)
       msym_obj = bound_minsym_to_minsym_object (&bound_minsym);
 

gdb/python/py-register.c

@@ -205,6 +205,7 @@ register_set_value(PyObject *self, PyObject *value_obj, void *closure)
 	      ret = write_register (regcache, obj->regnum, &ul_value);
 	    }
 	}
+#if PY_MAJOR_VERSION < 3
       else if (PyInt_Check (value_obj))
 	{
 	  ul_value = PyInt_AsUnsignedLongMask (value_obj);
@@ -216,6 +217,7 @@ register_set_value(PyObject *self, PyObject *value_obj, void *closure)
 	      ret = write_register (regcache, obj->regnum, &ul_value);
 	    }
 	}
+#endif
       else
 	{
 	  value = value_object_to_value(value_obj);