gdb: make gdbpy_parse_command_name return a unique_xmalloc_ptr

This avoids some manual memory management.

cmdpy_init correctly transfers ownership of the name to the
cmd_list_element, as it sets the name_allocated flag.  However,
cmdpy_init (and add_setshow_generic) doesn't, it looks like the name is
just leaked.  This is a bit tricky, because it actually creates two
commands (one set and one show), it would take a bit of refactoring of
the command code to give each their own allocated copy.  For now, just
keep doing what the current code does but in a more explicit fashion,
with an explicit release.

gdb/ChangeLog:

	* python/python-internal.h (gdbpy_parse_command_name): Return
	gdb::unique_xmalloc_ptr.
	* python/py-cmd.c (gdbpy_parse_command_name): Likewise.
	(cmdpy_init): Adjust.
	* python/py-param.c (parmpy_init): Adjust.
	(add_setshow_generic): Take gdb::unique_xmalloc_ptr, release it
	when done.

Change-Id: Iae5bc21fe2b22f12d5f954057b0aca7ca4cd3f0d

gdb/ChangeLog

@@ -1,3 +1,13 @@
+2021-05-12  Simon Marchi  <simon.marchi@polymtl.ca>
+
+	* python/python-internal.h (gdbpy_parse_command_name): Return
+	gdb::unique_xmalloc_ptr.
+	* python/py-cmd.c (gdbpy_parse_command_name): Likewise.
+	(cmdpy_init): Adjust.
+	* python/py-param.c (parmpy_init): Adjust.
+	(add_setshow_generic): Take gdb::unique_xmalloc_ptr, release it
+	when done.
+
 2021-05-12  George Barrett  <bob@bob131.so>
 
 	* NEWS (Guile API): Note the addition of the new procedure.

gdb/python/py-cmd.c

@@ -342,10 +342,10 @@ cmdpy_completer (struct cmd_list_element *command,
 
    START_LIST is the list in which the search starts.
 
-   This function returns the xmalloc()d name of the new command.  On
+   This function returns the name of the new command.  On error sets the Python
-   error sets the Python error and returns NULL.  */
+   error and returns NULL.  */
 
-char *
+gdb::unique_xmalloc_ptr<char>
 gdbpy_parse_command_name (const char *name,
 			  struct cmd_list_element ***base_list,
 			  struct cmd_list_element **start_list)
@@ -354,7 +354,6 @@ gdbpy_parse_command_name (const char *name,
   int len = strlen (name);
   int i, lastchar;
   const char *prefix_text2;
-  char *result;
 
   /* Skip trailing whitespace.  */
   for (i = len - 1; i >= 0 && (name[i] == ' ' || name[i] == '\t'); --i)
@@ -369,9 +368,10 @@ gdbpy_parse_command_name (const char *name,
   /* Find first character of the final word.  */
   for (; i > 0 && valid_cmd_char_p (name[i - 1]); --i)
     ;
-  result = (char *) xmalloc (lastchar - i + 2);
+
-  memcpy (result, &name[i], lastchar - i + 1);
+  gdb::unique_xmalloc_ptr<char> result ((char *) xmalloc (lastchar - i + 2));
-  result[lastchar - i + 1] = '\0';
+  memcpy (result.get (), &name[i], lastchar - i + 1);
+  result.get ()[lastchar - i + 1] = '\0';
 
   /* Skip whitespace again.  */
   for (--i; i >= 0 && (name[i] == ' ' || name[i] == '\t'); --i)
@@ -390,7 +390,6 @@ gdbpy_parse_command_name (const char *name,
     {
       PyErr_Format (PyExc_RuntimeError, _("Could not find command prefix %s."),
 		    prefix_text.c_str ());
-      xfree (result);
       return NULL;
     }
 
@@ -402,7 +401,6 @@ gdbpy_parse_command_name (const char *name,
 
   PyErr_Format (PyExc_RuntimeError, _("'%s' is not a prefix command."),
 		prefix_text.c_str ());
-  xfree (result);
   return NULL;
 }
 
@@ -435,7 +433,6 @@ cmdpy_init (PyObject *self, PyObject *args, PyObject *kw)
   int completetype = -1;
   char *docstring = NULL;
   struct cmd_list_element **cmd_list;
-  char *cmd_name;
   static const char *keywords[] = { "name", "command_class", "completer_class",
 				    "prefix", NULL };
   PyObject *is_prefix_obj = NULL;
@@ -474,19 +471,18 @@ cmdpy_init (PyObject *self, PyObject *args, PyObject *kw)
       return -1;
     }
 
-  cmd_name = gdbpy_parse_command_name (name, &cmd_list, &cmdlist);
+  gdb::unique_xmalloc_ptr<char> cmd_name
-  if (! cmd_name)
+    = gdbpy_parse_command_name (name, &cmd_list, &cmdlist);
+  if (cmd_name == nullptr)
     return -1;
 
   if (is_prefix_obj != NULL)
     {
       int cmp = PyObject_IsTrue (is_prefix_obj);
-       if (cmp < 0)
+      if (cmp < 0)
-	{
+	return -1;
-	  xfree (cmd_name);
+
-	  return -1;
+      is_prefix = cmp > 0;
-	}
-       is_prefix = cmp > 0;
     }
 
   if (PyObject_HasAttr (self, gdbpy_doc_cst))
@@ -497,10 +493,7 @@ cmdpy_init (PyObject *self, PyObject *args, PyObject *kw)
 	{
 	  docstring = python_string_to_host_string (ds_obj.get ()).release ();
 	  if (docstring == NULL)
-	    {
+	    return -1;
-	      xfree (cmd_name);
-	      return -1;
-	    }
 	}
     }
   if (! docstring)
@@ -519,14 +512,19 @@ cmdpy_init (PyObject *self, PyObject *args, PyObject *kw)
 	  /* If we have our own "invoke" method, then allow unknown
 	     sub-commands.  */
 	  allow_unknown = PyObject_HasAttr (self, invoke_cst);
-	  cmd = add_prefix_cmd (cmd_name, (enum command_class) cmdtype,
+	  cmd = add_prefix_cmd (cmd_name.get (),
+				(enum command_class) cmdtype,
 				NULL, docstring, &obj->sub_list,
 				allow_unknown, cmd_list);
 	}
       else
-	cmd = add_cmd (cmd_name, (enum command_class) cmdtype,
+	cmd = add_cmd (cmd_name.get (), (enum command_class) cmdtype,
 		       docstring, cmd_list);
 
+      /* If successful, the above takes ownership of the name, since we set
+         name_allocated, so release it.  */
+      cmd_name.release ();
+
       /* There appears to be no API to set this.  */
       cmd->func = cmdpy_function;
       cmd->destroyer = cmdpy_destroyer;
@@ -543,7 +541,6 @@ cmdpy_init (PyObject *self, PyObject *args, PyObject *kw)
     }
   catch (const gdb_exception &except)
     {
-      xfree (cmd_name);
       xfree (docstring);
       gdbpy_convert_exception (except);
       return -1;

gdb/python/py-param.c

@@ -458,7 +458,8 @@ get_show_value (struct ui_file *file, int from_tty,
    function.  */
 static void
 add_setshow_generic (int parmclass, enum command_class cmdclass,
-		     const char *cmd_name, parmpy_object *self,
+		     gdb::unique_xmalloc_ptr<char> cmd_name,
+		     parmpy_object *self,
 		     const char *set_doc, const char *show_doc,
 		     const char *help_doc,
 		     struct cmd_list_element **set_list,
@@ -471,7 +472,7 @@ add_setshow_generic (int parmclass, enum command_class cmdclass,
     {
     case var_boolean:
 
-      add_setshow_boolean_cmd (cmd_name, cmdclass,
+      add_setshow_boolean_cmd (cmd_name.get (), cmdclass,
 			       &self->value.boolval, set_doc, show_doc,
 			       help_doc, get_set_value, get_show_value,
 			       set_list, show_list);
@@ -479,7 +480,7 @@ add_setshow_generic (int parmclass, enum command_class cmdclass,
       break;
 
     case var_auto_boolean:
-      add_setshow_auto_boolean_cmd (cmd_name, cmdclass,
+      add_setshow_auto_boolean_cmd (cmd_name.get (), cmdclass,
 				    &self->value.autoboolval,
 				    set_doc, show_doc, help_doc,
 				    get_set_value, get_show_value,
@@ -487,26 +488,26 @@ add_setshow_generic (int parmclass, enum command_class cmdclass,
       break;
 
     case var_uinteger:
-      add_setshow_uinteger_cmd (cmd_name, cmdclass,
+      add_setshow_uinteger_cmd (cmd_name.get (), cmdclass,
 				&self->value.uintval, set_doc, show_doc,
 				help_doc, get_set_value, get_show_value,
 				set_list, show_list);
       break;
 
     case var_integer:
-      add_setshow_integer_cmd (cmd_name, cmdclass,
+      add_setshow_integer_cmd (cmd_name.get (), cmdclass,
 			       &self->value.intval, set_doc, show_doc,
 			       help_doc, get_set_value, get_show_value,
 			       set_list, show_list); break;
 
     case var_string:
-      add_setshow_string_cmd (cmd_name, cmdclass,
+      add_setshow_string_cmd (cmd_name.get (), cmdclass,
 			      &self->value.stringval, set_doc, show_doc,
 			      help_doc, get_set_value, get_show_value,
 			      set_list, show_list); break;
 
     case var_string_noescape:
-      add_setshow_string_noescape_cmd (cmd_name, cmdclass,
+      add_setshow_string_noescape_cmd (cmd_name.get (), cmdclass,
 				       &self->value.stringval,
 				       set_doc, show_doc, help_doc,
 				       get_set_value, get_show_value,
@@ -515,7 +516,7 @@ add_setshow_generic (int parmclass, enum command_class cmdclass,
       break;
 
     case var_optional_filename:
-      add_setshow_optional_filename_cmd (cmd_name, cmdclass,
+      add_setshow_optional_filename_cmd (cmd_name.get (), cmdclass,
 					 &self->value.stringval, set_doc,
 					 show_doc, help_doc, get_set_value,
 					 get_show_value, set_list,
@@ -523,27 +524,27 @@ add_setshow_generic (int parmclass, enum command_class cmdclass,
       break;
 
     case var_filename:
-      add_setshow_filename_cmd (cmd_name, cmdclass,
+      add_setshow_filename_cmd (cmd_name.get (), cmdclass,
 				&self->value.stringval, set_doc, show_doc,
 				help_doc, get_set_value, get_show_value,
 				set_list, show_list); break;
 
     case var_zinteger:
-      add_setshow_zinteger_cmd (cmd_name, cmdclass,
+      add_setshow_zinteger_cmd (cmd_name.get (), cmdclass,
 				&self->value.intval, set_doc, show_doc,
 				help_doc, get_set_value, get_show_value,
 				set_list, show_list);
       break;
 
     case var_zuinteger:
-      add_setshow_zuinteger_cmd (cmd_name, cmdclass,
+      add_setshow_zuinteger_cmd (cmd_name.get (), cmdclass,
 				&self->value.uintval, set_doc, show_doc,
 				help_doc, get_set_value, get_show_value,
 				set_list, show_list);
       break;
 
     case var_zuinteger_unlimited:
-      add_setshow_zuinteger_unlimited_cmd (cmd_name, cmdclass,
+      add_setshow_zuinteger_unlimited_cmd (cmd_name.get (), cmdclass,
 					   &self->value.intval, set_doc,
 					   show_doc, help_doc, get_set_value,
 					   get_show_value,
@@ -551,7 +552,7 @@ add_setshow_generic (int parmclass, enum command_class cmdclass,
       break;
 
     case var_enum:
-      add_setshow_enum_cmd (cmd_name, cmdclass, self->enumeration,
+      add_setshow_enum_cmd (cmd_name.get (), cmdclass, self->enumeration,
 			    &self->value.cstringval, set_doc, show_doc,
 			    help_doc, get_set_value, get_show_value,
 			    set_list, show_list);
@@ -562,15 +563,18 @@ add_setshow_generic (int parmclass, enum command_class cmdclass,
 
   /* Lookup created parameter, and register Python object against the
      parameter context.  Perform this task against both lists.  */
-  tmp_name = cmd_name;
+  tmp_name = cmd_name.get ();
   param = lookup_cmd (&tmp_name, *show_list, "", NULL, 0, 1);
   if (param)
     set_cmd_context (param, self);
 
-  tmp_name = cmd_name;
+  tmp_name = cmd_name.get ();
   param = lookup_cmd (&tmp_name, *set_list, "", NULL, 0, 1);
   if (param)
     set_cmd_context (param, self);
+
+  /* We (unfortunately) currently leak the command name.  */
+  cmd_name.release ();
 }
 
 /* A helper which computes enum values.  Returns 1 on success.  Returns 0 on
@@ -657,7 +661,6 @@ parmpy_init (PyObject *self, PyObject *args, PyObject *kwds)
   parmpy_object *obj = (parmpy_object *) self;
   const char *name;
   gdb::unique_xmalloc_ptr<char> set_doc, show_doc, doc;
-  char *cmd_name;
   int parmclass, cmdtype;
   PyObject *enum_values = NULL;
   struct cmd_list_element **set_list, **show_list;
@@ -706,15 +709,13 @@ parmpy_init (PyObject *self, PyObject *args, PyObject *kwds)
   obj->type = (enum var_types) parmclass;
   memset (&obj->value, 0, sizeof (obj->value));
 
-  cmd_name = gdbpy_parse_command_name (name, &set_list,
+  gdb::unique_xmalloc_ptr<char> cmd_name
-				       &setlist);
+    = gdbpy_parse_command_name (name, &set_list, &setlist);
-
+  if (cmd_name == nullptr)
-  if (! cmd_name)
     return -1;
-  xfree (cmd_name);
+
-  cmd_name = gdbpy_parse_command_name (name, &show_list,
+  cmd_name = gdbpy_parse_command_name (name, &show_list, &showlist);
-				       &showlist);
+  if (cmd_name == nullptr)
-  if (! cmd_name)
     return -1;
 
   set_doc = get_doc_string (self, set_doc_cst);
@@ -726,13 +727,12 @@ parmpy_init (PyObject *self, PyObject *args, PyObject *kwds)
   try
     {
       add_setshow_generic (parmclass, (enum command_class) cmdtype,
-			   cmd_name, obj,
+			   std::move (cmd_name), obj,
 			   set_doc.get (), show_doc.get (),
 			   doc.get (), set_list, show_list);
     }
   catch (const gdb_exception &except)
     {
-      xfree (cmd_name);
       Py_DECREF (self);
       gdbpy_convert_exception (except);
       return -1;

gdb/python/python-internal.h

@@ -439,9 +439,9 @@ PyObject *gdbpy_selected_thread (PyObject *self, PyObject *args);
 PyObject *gdbpy_selected_inferior (PyObject *self, PyObject *args);
 PyObject *gdbpy_string_to_argv (PyObject *self, PyObject *args);
 PyObject *gdbpy_parameter_value (enum var_types type, void *var);
-char *gdbpy_parse_command_name (const char *name,
+gdb::unique_xmalloc_ptr<char> gdbpy_parse_command_name
-				struct cmd_list_element ***base_list,
+  (const char *name, struct cmd_list_element ***base_list,
-				struct cmd_list_element **start_list);
+   struct cmd_list_element **start_list);
 PyObject *gdbpy_register_tui_window (PyObject *self, PyObject *args,
 				     PyObject *kw);