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, 8 insertions, 9 deletions

diff --git a/gdb/python/py-cmd.c b/gdb/python/py-cmd.c
index af6c5cf..8333789 100644
--- a/gdb/python/py-cmd.c
+++ b/gdb/python/py-cmd.c
@@ -156,7 +156,6 @@ cmdpy_function (struct cmd_list_element *command, char *args, int from_tty)
   if (! result)
     {
       PyObject *ptype, *pvalue, *ptraceback;
-      char *msg;
 
       PyErr_Fetch (&ptype, &pvalue, &ptraceback);
 
@@ -164,8 +163,8 @@ cmdpy_function (struct cmd_list_element *command, char *args, int from_tty)
 	 When fetching the error message we need to make our own copy,
 	 we no longer own ptype, pvalue after the call to PyErr_Restore.  */
 
-      msg = gdbpy_exception_to_string (ptype, pvalue);
-      make_cleanup (xfree, msg);
+      gdb::unique_xmalloc_ptr<char>
+	msg (gdbpy_exception_to_string (ptype, pvalue));
 
       if (msg == NULL)
 	{
@@ -190,7 +189,7 @@ cmdpy_function (struct cmd_list_element *command, char *args, int from_tty)
 	  PyErr_Restore (ptype, pvalue, ptraceback);
 	  gdbpy_print_stack ();
 	  if (msg != NULL && *msg != '\0')
-	    error (_("Error occurred in Python command: %s"), msg);
+	    error (_("Error occurred in Python command: %s"), msg.get ());
 	  else
 	    error (_("Error occurred in Python command."));
 	}
@@ -199,7 +198,7 @@ cmdpy_function (struct cmd_list_element *command, char *args, int from_tty)
 	  Py_XDECREF (ptype);
 	  Py_XDECREF (pvalue);
 	  Py_XDECREF (ptraceback);
-	  error ("%s", msg);
+	  error ("%s", msg.get ());
 	}
     }
 
@@ -374,7 +373,6 @@ cmdpy_completer (struct cmd_list_element *command,
 
       while ((elt = PyIter_Next (iter)) != NULL)
 	{
-	  char *item;
 
 	  if (! gdbpy_is_string (elt))
 	    {
@@ -382,7 +380,8 @@ cmdpy_completer (struct cmd_list_element *command,
 	      Py_DECREF (elt);
 	      continue;
 	    }
-	  item = python_string_to_host_string (elt);
+	  gdb::unique_xmalloc_ptr<char>
+	    item (python_string_to_host_string (elt));
 	  Py_DECREF (elt);
 	  if (item == NULL)
 	    {
@@ -390,7 +389,7 @@ cmdpy_completer (struct cmd_list_element *command,
 	      PyErr_Clear ();
 	      continue;
 	    }
-	  VEC_safe_push (char_ptr, result, item);
+	  VEC_safe_push (char_ptr, result, item.release ());
 	}
 
       Py_DECREF (iter);
@@ -604,7 +603,7 @@ cmdpy_init (PyObject *self, PyObject *args, PyObject *kw)
 
       if (ds_obj && gdbpy_is_string (ds_obj))
 	{
-	  docstring = python_string_to_host_string (ds_obj);
+	  docstring = python_string_to_host_string (ds_obj).release ();
 	  if (docstring == NULL)
 	    {
 	      xfree (cmd_name);