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, 5 insertions, 3 deletions

diff --git a/gdb/python/py-infthread.c b/gdb/python/py-infthread.c
index 697298d..3cc359c 100644
--- a/gdb/python/py-infthread.c
+++ b/gdb/python/py-infthread.c
@@ -80,7 +80,7 @@ static int
 thpy_set_name (PyObject *self, PyObject *newvalue, void *ignore)
 {
   thread_object *thread_obj = (thread_object *) self;
-  char *name;
+  gdb::unique_xmalloc_ptr<char> name;
 
   if (! thread_obj->thread)
     {
@@ -95,7 +95,9 @@ thpy_set_name (PyObject *self, PyObject *newvalue, void *ignore)
       return -1;
     }
   else if (newvalue == Py_None)
-    name = NULL;
+    {
+      /* Nothing.  */
+    }
   else if (! gdbpy_is_string (newvalue))
     {
       PyErr_SetString (PyExc_TypeError,
@@ -110,7 +112,7 @@ thpy_set_name (PyObject *self, PyObject *newvalue, void *ignore)
     }
 
   xfree (thread_obj->thread->name);
-  thread_obj->thread->name = name;
+  thread_obj->thread->name = name.release ();
 
   return 0;
 }