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, 20 insertions, 26 deletions

diff --git a/gdb/python/py-param.c b/gdb/python/py-param.c
index 3604f9f..0d19c97 100644
--- a/gdb/python/py-param.c
+++ b/gdb/python/py-param.c
@@ -148,21 +148,19 @@ set_parameter_value (parmpy_object *self, PyObject *value)
 	}
       else
 	{
-	  char *string;
-
-	  string = python_string_to_host_string (value);
+	  gdb::unique_xmalloc_ptr<char>
+	    string (python_string_to_host_string (value));
 	  if (string == NULL)
 	    return -1;
 
 	  xfree (self->value.stringval);
-	  self->value.stringval = string;
+	  self->value.stringval = string.release ();
 	}
       break;
 
     case var_enum:
       {
 	int i;
-	char *str;
 
 	if (! gdbpy_is_string (value))
 	  {
@@ -171,13 +169,13 @@ set_parameter_value (parmpy_object *self, PyObject *value)
 	    return -1;
 	  }
 
-	str = python_string_to_host_string (value);
+	gdb::unique_xmalloc_ptr<char>
+	  str (python_string_to_host_string (value));
 	if (str == NULL)
 	  return -1;
 	for (i = 0; self->enumeration[i]; ++i)
-	  if (! strcmp (self->enumeration[i], str))
+	  if (! strcmp (self->enumeration[i], str.get ()))
 	    break;
-	xfree (str);
 	if (! self->enumeration[i])
 	  {
 	    PyErr_SetString (PyExc_RuntimeError,
@@ -301,10 +299,10 @@ set_attr (PyObject *obj, PyObject *attr_name, PyObject *val)
 /* A helper function which returns a documentation string for an
    object. */
 
-static char *
+static gdb::unique_xmalloc_ptr<char>
 get_doc_string (PyObject *object, PyObject *attr)
 {
-  char *result = NULL;
+  gdb::unique_xmalloc_ptr<char> result;
 
   if (PyObject_HasAttr (object, attr))
     {
@@ -319,7 +317,7 @@ get_doc_string (PyObject *object, PyObject *attr)
       Py_XDECREF (ds_obj);
     }
   if (! result)
-    result = xstrdup (_("This command is not documented."));
+    result.reset (xstrdup (_("This command is not documented.")));
   return result;
 }
 
@@ -327,10 +325,10 @@ get_doc_string (PyObject *object, PyObject *attr)
    argument ARG.  ARG can be NULL.  METHOD should return a Python
    string.  If this function returns NULL, there has been an error and
    the appropriate exception set.  */
-static char *
+static gdb::unique_xmalloc_ptr<char>
 call_doc_function (PyObject *obj, PyObject *method, PyObject *arg)
 {
-  char *data = NULL;
+  gdb::unique_xmalloc_ptr<char> data;
   PyObject *result = PyObject_CallMethodObjArgs (obj, method, arg, NULL);
 
   if (! result)
@@ -365,7 +363,7 @@ get_set_value (char *args, int from_tty,
 	       struct cmd_list_element *c)
 {
   PyObject *obj = (PyObject *) get_cmd_context (c);
-  char *set_doc_string;
+  gdb::unique_xmalloc_ptr<char> set_doc_string;
   struct cleanup *cleanup = ensure_python_env (get_current_arch (),
 					       current_language);
   PyObject *set_doc_func = PyString_FromString ("get_set_string");
@@ -387,8 +385,7 @@ get_set_value (char *args, int from_tty,
       set_doc_string  = get_doc_string (obj, set_doc_cst);
     }
 
-  make_cleanup (xfree, set_doc_string);
-  fprintf_filtered (gdb_stdout, "%s\n", set_doc_string);
+  fprintf_filtered (gdb_stdout, "%s\n", set_doc_string.get ());
 
   Py_XDECREF (set_doc_func);
   do_cleanups (cleanup);
@@ -413,7 +410,7 @@ get_show_value (struct ui_file *file, int from_tty,
 		const char *value)
 {
   PyObject *obj = (PyObject *) get_cmd_context (c);
-  char *show_doc_string = NULL;
+  gdb::unique_xmalloc_ptr<char> show_doc_string;
   struct cleanup *cleanup = ensure_python_env (get_current_arch (),
 					       current_language);
   PyObject *show_doc_func = PyString_FromString ("get_show_string");
@@ -433,9 +430,7 @@ get_show_value (struct ui_file *file, int from_tty,
       if (! show_doc_string)
 	goto error;
 
-      make_cleanup (xfree, show_doc_string);
-
-      fprintf_filtered (file, "%s\n", show_doc_string);
+      fprintf_filtered (file, "%s\n", show_doc_string.get ());
     }
   else
     {
@@ -443,8 +438,7 @@ get_show_value (struct ui_file *file, int from_tty,
 	 callback function does not exist, then attempt to read the
 	 show_doc attribute.  */
       show_doc_string  = get_doc_string (obj, show_doc_cst);
-      make_cleanup (xfree, show_doc_string);
-      fprintf_filtered (file, "%s %s\n", show_doc_string, value);
+      fprintf_filtered (file, "%s %s\n", show_doc_string.get (), value);
     }
 
   Py_XDECREF (show_doc_func);
@@ -614,7 +608,7 @@ compute_enum_values (parmpy_object *self, PyObject *enum_values)
 			   _("The enumeration item not a string."));
 	  return 0;
 	}
-      self->enumeration[i] = python_string_to_host_string (item);
+      self->enumeration[i] = python_string_to_host_string (item).release ();
       Py_DECREF (item);
       if (self->enumeration[i] == NULL)
 	{
@@ -716,9 +710,9 @@ parmpy_init (PyObject *self, PyObject *args, PyObject *kwds)
   if (! cmd_name)
     return -1;
 
-  set_doc = get_doc_string (self, set_doc_cst);
-  show_doc = get_doc_string (self, show_doc_cst);
-  doc = get_doc_string (self, gdbpy_doc_cst);
+  set_doc = get_doc_string (self, set_doc_cst).release ();
+  show_doc = get_doc_string (self, show_doc_cst).release ();
+  doc = get_doc_string (self, gdbpy_doc_cst).release ();
 
   Py_INCREF (self);