Re: [RFA] Avoid recursivly defined user functions.

[Michael Snyder <msnyder@redhat.com>]

Don Howard wrote:
> 
> 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.

So do I.   ;-)

> >
> 
> 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);
> 
> +/* 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