Use unique_xmalloc_ptr in Python code

This changes some utility functions in the Python code to return
unique_xmalloc_ptr, and then fixes up the callers.

I chose unique_xmalloc_ptr rather than std::string because at a few
call points the xmalloc'd string is released and ownership transferred
elsewhere.

This patch found a few existing memory leaks.  For example,
py-unwind.c called gdbpy_obj_to_string but never freed the result.

Built and regression tested on the buildbot.

2016-11-09  Tom Tromey  <tom@tromey.com>

	* varobj.h (varobj_get_display_hint): Change return type.
	* varobj.c (varobj_get_display_hint): Return unique_xmalloc_ptr.
	(varobj_value_get_print_value): Update.
	* python/python.c (gdbpy_before_prompt_hook, gdbpy_print_stack)
	(gdbpy_apply_type_printers): Update.
	* python/python-internal.h (unicode_to_target_string)
	(python_string_to_target_string, python_string_to_host_string)
	(gdbpy_obj_to_string, gdbpy_exception_to_string)
	(gdbpy_get_display_hint): Change return types.
	* python/py-varobj.c (py_varobj_iter_next): Update.
	* python/py-value.c (valpy_getitem, convert_value_from_python):
	Update.
	* python/py-utils.c (unicode_to_encoded_string)
	(unicode_to_target_string, python_string_to_target_string)
	(python_string_to_host_string, gdbpy_obj_to_string)
	(gdbpy_exception_to_string): Return unique_xmalloc_ptr.
	* python/py-unwind.c (pyuw_parse_register_id): Update.
	* python/py-type.c (typy_getitem): Update.
	* python/py-prettyprint.c (gdbpy_get_display_hint)
	(print_stack_unless_memory_error, print_children)
	(gdbpy_apply_val_pretty_printer): Update.
	* python/py-param.c (set_parameter_value): Update.
	(get_doc_string, call_doc_function): Return unique_xmalloc_ptr.
	(get_set_value, get_show_value, compute_enum_values, parmpy_init):
	Update.
	* python/py-infthread.c (thpy_set_name): Update.
	* python/py-function.c (fnpy_call, fnpy_init): Update.
	* python/py-framefilter.c (extract_sym): Change "name" to
	unique_xmalloc_ptr.
	(enumerate_args, enumerate_locals): Update.
	(py_print_frame): Use unique_xmalloc_ptr.
	* python/py-frame.c (frapy_read_var): Update.  Remove cleanup.
	* python/py-cmd.c (cmdpy_function, cmdpy_completer, cmdpy_init):
	Update.
	* python/py-breakpoint.c (bppy_set_condition): Use
	unique_xmalloc_ptr.
	(bppy_init): Likewise.  Remove cleanup.
	(local_setattro): Update.
	* mi/mi-cmd-var.c (print_varobj, mi_cmd_var_list_children)
	(varobj_update_one): Update.

1 files changed, 4 insertions, 11 deletions

diff --git a/gdb/python/py-frame.c b/gdb/python/py-frame.c
index a66f885..7c95803 100644
--- a/gdb/python/py-frame.c
+++ b/gdb/python/py-frame.c
@@ -514,13 +514,11 @@ frapy_read_var (PyObject *self, PyObject *args)
     var = symbol_object_to_symbol (sym_obj);
   else if (gdbpy_is_string (sym_obj))
     {
-      char *var_name;
-      struct cleanup *cleanup;
+      gdb::unique_xmalloc_ptr<char>
+	var_name (python_string_to_target_string (sym_obj));
 
-      var_name = python_string_to_target_string (sym_obj);
       if (!var_name)
 	return NULL;
-      cleanup = make_cleanup (xfree, var_name);
 
       if (block_obj)
 	{
@@ -529,7 +527,6 @@ frapy_read_var (PyObject *self, PyObject *args)
 	    {
 	      PyErr_SetString (PyExc_RuntimeError,
 			       _("Second argument must be block."));
-	      do_cleanups (cleanup);
 	      return NULL;
 	    }
 	}
@@ -541,13 +538,12 @@ frapy_read_var (PyObject *self, PyObject *args)
 
 	  if (!block)
 	    block = get_frame_block (frame, NULL);
-	  lookup_sym = lookup_symbol (var_name, block, VAR_DOMAIN, NULL);
+	  lookup_sym = lookup_symbol (var_name.get (), block, VAR_DOMAIN, NULL);
 	  var = lookup_sym.symbol;
 	  block = lookup_sym.block;
 	}
       CATCH (except, RETURN_MASK_ALL)
 	{
-	  do_cleanups (cleanup);
 	  gdbpy_convert_exception (except);
 	  return NULL;
 	}
@@ -556,13 +552,10 @@ frapy_read_var (PyObject *self, PyObject *args)
       if (!var)
 	{
 	  PyErr_Format (PyExc_ValueError,
-			_("Variable '%s' not found."), var_name);
-	  do_cleanups (cleanup);
+			_("Variable '%s' not found."), var_name.get ());
 
 	  return NULL;
 	}
-
-      do_cleanups (cleanup);
     }
   else
     {