Re: [RFA] Avoid recursivly defined user functions.

Don Howard
2002-04-11T17:56:15Z

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