Re: [RFA] Avoid recursivly defined user functions.

[Don Howard <dhoward@redhat.com>]

On Tue, 9 Apr 2002, Don Howard wrote:

> On Tue, 9 Apr 2002, Paul Hilfinger wrote:
> 
> > 
> > > How about something even simpler - track user command depth at runtime? 
> > > Set an absurd limit, like 1024 deep, if we can handle that in a
> > > normal-sized stack limit.  Then complain if we hit it at runtime.
> > 
> > I completely agree with this.  After all, if you were willing to
> > contemplate outlawing recursion altogether, you certainly won't LOSE
> > anything by Daniel's approach, and you gain everything you wanted in
> > the first place---to avoid crashing GDB.  
> > 
> > Paul
> > 
> 
> 
> I like this approach, also.  
> 


2002-04-11  Don Howard  <dhoward@redhat.com>

	* cli/cli-cmds.c (init_cli_cmds): Add new user settable value:
	max_user_call_depth.
	(init_cmd_lists): Initialize the new value;
	* cli/cli-script.c (execute_user_command): Limit the call depth of
	user defined commands.  This avoids a core-dump when user commands
	are infinitly recursive.



Index: cli/cli-cmds.c
===================================================================
RCS file: /cvs/src/src/gdb/cli/cli-cmds.c,v
retrieving revision 1.18
diff -p -u -w -r1.18 cli-cmds.c
--- cli/cli-cmds.c	28 Mar 2002 01:35:56 -0000	1.18
+++ cli/cli-cmds.c	11 Apr 2002 17:30:58 -0000
@@ -80,6 +80,9 @@ static void shell_escape (char *, int);
 
 void apropos_command (char *, int);
 \f
+/* Limit the call depth of user-defined commands */
+int max_user_call_depth;
+
 /* Define all cmd_list_elements.  */
 
 /* Chain containing all defined commands.  */
@@ -606,6 +609,8 @@ show_debug (char *args, int from_tty)
 void
 init_cmd_lists (void)
 {
+  max_user_call_depth = 1024;
+
   cmdlist = NULL;
   infolist = NULL;
   enablelist = NULL;
@@ -823,4 +828,11 @@ With no arguments, run an inferior shell
 Argument is the name of the user defined command.\n\
 With no argument, show definitions of all user defined commands.", &showlist);
   add_com ("apropos", class_support, apropos_command, "Search for commands matching a REGEXP");
+
+  add_show_from_set (
+		      add_set_cmd ("max_user_call_depth", no_class, var_integer, 
+				   (char *) &max_user_call_depth,
+				   "Set the max call depth for user-defined commands.\n", 
+				   &setlist),
+		      &showlist);
 }
Index: cli/cli-script.c
===================================================================
RCS file: /cvs/src/src/gdb/cli/cli-script.c,v
retrieving revision 1.11
diff -p -u -w -r1.11 cli-script.c
--- cli/cli-script.c	17 Mar 2002 19:53:39 -0000	1.11
+++ cli/cli-script.c	11 Apr 2002 17:30:59 -0000
@@ -247,6 +247,15 @@ execute_cmd_post_hook (struct cmd_list_e
 }
 
 /* Execute the command in CMD.  */
+void
+do_restore_user_call_depth (void * call_depth)
+{	
+  int * depth = call_depth;
+  /* We will be returning_to_top_level() at this point, so we want to
+     reset our depth. */
+  (*depth) = 0;
+}
+
 
 void
 execute_user_command (struct cmd_list_element *c, char *args)
@@ -254,6 +263,8 @@ execute_user_command (struct cmd_list_el
   register struct command_line *cmdlines;
   struct cleanup *old_chain;
   enum command_control_type ret;
+  static int user_call_depth = 0;
+  extern int max_user_call_depth;
 
   old_chain = setup_user_args (args);
 
@@ -262,6 +273,11 @@ execute_user_command (struct cmd_list_el
     /* Null command */
     return;
 
+  if (user_call_depth++ > max_user_call_depth)
+    error ("Max user call depth exceeded -- command aborted\n");
+
+  old_chain = make_cleanup (do_restore_user_call_depth, &user_call_depth);
+
   /* Set the instream to 0, indicating execution of a
      user-defined function.  */
   old_chain = make_cleanup (do_restore_instream_cleanup, instream);
@@ -277,6 +293,8 @@ execute_user_command (struct cmd_list_el
       cmdlines = cmdlines->next;
     }
   do_cleanups (old_chain);
+
+  user_call_depth--;
 }
 
 enum command_control_type


-- 
dhoward@redhat.com
gdb engineering