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, 4 deletions

diff --git a/gdb/python/py-varobj.c b/gdb/python/py-varobj.c
index a6b1968..72c876c 100644
--- a/gdb/python/py-varobj.c
+++ b/gdb/python/py-varobj.c
@@ -75,10 +75,11 @@ py_varobj_iter_next (struct varobj_iter *self)
       if (PyErr_ExceptionMatches (gdbpy_gdb_memory_error))
 	{
 	  PyObject *type, *value, *trace;
-	  char *name_str, *value_str;
+	  char *name_str;
 
 	  PyErr_Fetch (&type, &value, &trace);
-	  value_str = gdbpy_exception_to_string (type, value);
+	  gdb::unique_xmalloc_ptr<char>
+	    value_str (gdbpy_exception_to_string (type, value));
 	  Py_XDECREF (type);
 	  Py_XDECREF (value);
 	  Py_XDECREF (trace);
@@ -90,9 +91,8 @@ py_varobj_iter_next (struct varobj_iter *self)
 
 	  name_str = xstrprintf ("<error at %d>",
 				 self->next_raw_index++);
-	  item = Py_BuildValue ("(ss)", name_str, value_str);
+	  item = Py_BuildValue ("(ss)", name_str, value_str.get ());
 	  xfree (name_str);
-	  xfree (value_str);
 	  if (item == NULL)
 	    {
 	      gdbpy_print_stack ();