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, 7 insertions, 8 deletions

diff --git a/gdb/python/py-function.c b/gdb/python/py-function.c
index d42dbde..800605a 100644
--- a/gdb/python/py-function.c
+++ b/gdb/python/py-function.c
@@ -94,7 +94,6 @@ fnpy_call (struct gdbarch *gdbarch, const struct language_defn *language,
   if (!result)
     {
       PyObject *ptype, *pvalue, *ptraceback;
-      char *msg;
 
       PyErr_Fetch (&ptype, &pvalue, &ptraceback);
 
@@ -102,8 +101,8 @@ fnpy_call (struct gdbarch *gdbarch, const struct language_defn *language,
 	 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)
 	{
@@ -131,7 +130,7 @@ fnpy_call (struct gdbarch *gdbarch, const struct language_defn *language,
 	  gdbpy_print_stack ();
 	  if (msg != NULL && *msg != '\0')
 	    error (_("Error occurred in Python convenience function: %s"),
-		   msg);
+		   msg.get ());
 	  else
 	    error (_("Error occurred in Python convenience function."));
 	}
@@ -140,7 +139,7 @@ fnpy_call (struct gdbarch *gdbarch, const struct language_defn *language,
 	  Py_XDECREF (ptype);
 	  Py_XDECREF (pvalue);
 	  Py_XDECREF (ptraceback);
-	  error ("%s", msg);
+	  error ("%s", msg.get ());
 	}
     }
 
@@ -165,7 +164,7 @@ static int
 fnpy_init (PyObject *self, PyObject *args, PyObject *kwds)
 {
   const char *name;
-  char *docstring = NULL;
+  gdb::unique_xmalloc_ptr<char> docstring;
 
   if (! PyArg_ParseTuple (args, "s", &name))
     return -1;
@@ -191,9 +190,9 @@ fnpy_init (PyObject *self, PyObject *args, PyObject *kwds)
 	}
     }
   if (! docstring)
-    docstring = xstrdup (_("This function is not documented."));
+    docstring.reset (xstrdup (_("This function is not documented.")));
 
-  add_internal_function (name, docstring, fnpy_call, self);
+  add_internal_function (name, docstring.release (), fnpy_call, self);
   return 0;
 }