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/varobj.c b/gdb/varobj.c
index afd82d2..03edf0e 100644
--- a/gdb/varobj.c
+++ b/gdb/varobj.c
@@ -557,10 +557,10 @@ varobj_get_display_format (const struct varobj *var)
   return var->format;
 }
 
-char *
+gdb::unique_xmalloc_ptr<char>
 varobj_get_display_hint (const struct varobj *var)
 {
-  char *result = NULL;
+  gdb::unique_xmalloc_ptr<char> result;
 
 #if HAVE_PYTHON
   struct cleanup *back_to;
@@ -2484,26 +2484,25 @@ varobj_value_get_print_value (struct value *value,
 			 string_print.  Otherwise just return the extracted
 			 string as a value.  */
 
-		      char *s = python_string_to_target_string (output);
+		      gdb::unique_xmalloc_ptr<char> s
+			= python_string_to_target_string (output);
 
 		      if (s)
 			{
 			  struct gdbarch *gdbarch;
-			  char *hint;
 
-			  hint = gdbpy_get_display_hint (value_formatter);
+			  gdb::unique_xmalloc_ptr<char> hint
+			    = gdbpy_get_display_hint (value_formatter);
 			  if (hint)
 			    {
-			      if (!strcmp (hint, "string"))
+			      if (!strcmp (hint.get (), "string"))
 				string_print = 1;
-			      xfree (hint);
 			    }
 
-			  thevalue = std::string (s);
+			  thevalue = std::string (s.get ());
 			  len = thevalue.size ();
 			  gdbarch = get_type_arch (value_type (value));
 			  type = builtin_type (gdbarch)->builtin_char;
-			  xfree (s);
 
 			  if (!string_print)
 			    {