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Re: [RFA] deleting breakpoints inside of 'commands' (again)
- From: Don Howard <dhoward at redhat dot com>
- To: Andrew Cagney <ac131313 at cygnus dot com>
- Cc: Michael Snyder <msnyder at cygnus dot com>, Fernando Nasser <fnasser at redhat dot com>, <gdb-patches at sources dot redhat dot com>
- Date: Wed, 3 Apr 2002 13:57:58 -0800 (PST)
- Subject: Re: [RFA] deleting breakpoints inside of 'commands' (again)
[patch ping]
I never received any feedback on this, and had forgotten about it.
Comments?
On Fri, 14 Dec 2001, Don Howard wrote:
> On Tue, 6 Nov 2001, Andrew Cagney wrote:
>
> > >
> > > Doesn't the function below catch that? There is a recursive call to
> > > look for just the problem that you mention. Is there some other way of
> > > deleting commands that I need to look out for?
> >
> > I'm not sure.
> >
> > Consider:
> >
> > command callee
> > delete command callee
> > end
> > breakpoint foo
> > commands $bp
> > callee
> > end
> >
> > it will realise that there is a delete but will it protect its self from
> > a command deleting its self.
> >
> > > [BTW, I personally think that the unconditional copy is much less
> > > error prone (and therefore better) even if it's slower. Just my $0.02]
> >
> > Agreed (And slower is relative - what happens if there are 100's or
> > 1000's of commands - that search becomes the bottle neck.)
> >
> > Andrew
>
>
>
>
> I've added a call to lookup_cmd(). This allows user-defined commands to
> be examined also, which should address your concern.
>
> I've also added checks that examine the pre and post hook commands.
>
>
>
> 2001-12-13 Don Howard <dhoward@redhat.com>
>
> * breakpoint.c (bpstat_do_actions): Avoid deleting a 'commands'
> list while executing that list. Thanks to Pierre Muller
> <muller@ics.u-strasbg.fr> for suggesting this implementation.
> (cleanup_dup_command_lines): New function.
> (bpstat_actions_delete_breakpoints): Ditto.
> * cli/cli-script.c (dup_command_lines): New function.
> * defs.h: Added declaration of new function.
>
>
> Index: gdb/breakpoint.c
> ===================================================================
> RCS file: /cvs/src/src/gdb/breakpoint.c,v
> retrieving revision 1.57
> diff -p -u -w -r1.57 breakpoint.c
> --- breakpoint.c 2001/11/11 16:39:59 1.57
> +++ breakpoint.c 2001/12/14 08:13:07
> @@ -1790,6 +1790,102 @@ cleanup_executing_breakpoints (PTR ignor
> executing_breakpoint_commands = 0;
> }
>
> +static void
> +cleanup_dup_command_lines (PTR cmds)
> +{
> + free_command_lines (cmds);
> +}
> +
> +
> +/* Walk a list of struct command_lines and try to determine if any
> + command deletes breakpoints */
> +
> +static int
> +bpstat_actions_delete_breakpoints (struct command_line * cmd)
> +{
> + for (; cmd; cmd = cmd->next)
> + {
> + struct cmd_list_element *ce;
> + char *line = cmd->line;
> + int i;
> + int ret;
> +
> + ce = lookup_cmd (&line, cmdlist, "", 0, 1);
> +
> + if (ce == NULL)
> + return 0;
> +
> +
> + /* Check the command */
> + if (ce->class == class_user && !ce->hook_in)
> + {
> + ce->hook_in = 1;
> + ret = bpstat_actions_delete_breakpoints (ce->user_commands);
> + ce->hook_in = 0;
> +
> + if (ret)
> + return 1;
> + }
> + else if (strcmp (ce->name, "delete") == 0
> + || strcmp (ce->name, "clear") == 0)
> + {
> + return 1;
> + }
> +
> +
> + /* Check the pre-hook */
> + if (ce->hook_pre)
> + {
> + if (ce->hook_pre->class == class_user && !ce->hook_in)
> + {
> + ce->hook_in = 1;
> + ret = bpstat_actions_delete_breakpoints (ce->hook_pre->user_commands);
> + ce->hook_in = 0;
> +
> + if (ret)
> + return 1;
> + }
> + else if (strcmp (ce->hook_pre->name, "delete") == 0
> + || strcmp (ce->hook_pre->name, "clear") == 0)
> + {
> + return 1;
> + }
> + }
> +
> +
> + /* Check the post-hook */
> + if (ce->hook_post)
> + {
> + if (ce->hook_post->class == class_user && !ce->hook_in)
> + {
> + ce->hook_in = 1;
> + ret = bpstat_actions_delete_breakpoints (ce->hook_post->user_commands);
> + ce->hook_in = 0;
> +
> + if (ret)
> + return 1;
> + }
> + else if (strcmp (ce->hook_post->name, "delete") == 0
> + || strcmp (ce->hook_post->name, "clear") == 0)
> + {
> + return 1;
> + }
> + }
> +
> +
> + /* If this is a multi-part command (while, if, etc), check the
> + body. */
> + for (i=0; i<cmd->body_count; i++)
> + if (bpstat_actions_delete_breakpoints (cmd->body_list[i]))
> + return 1;
> +
> + }
> +
> + return 0;
> +
> +}
> +
> +
> /* Execute all the commands associated with all the breakpoints at this
> location. Any of these commands could cause the process to proceed
> beyond this point, etc. We look out for such changes by checking
> @@ -1800,7 +1896,6 @@ bpstat_do_actions (bpstat *bsp)
> {
> bpstat bs;
> struct cleanup *old_chain;
> - struct command_line *cmd;
>
> /* Avoid endless recursion if a `source' command is contained
> in bs->commands. */
> @@ -1825,16 +1920,37 @@ top:
> breakpoint_proceeded = 0;
> for (; bs != NULL; bs = bs->next)
> {
> - cmd = bs->commands;
> - while (cmd != NULL)
> + struct command_line *cmd;
> + struct cleanup *new_old_chain;
> +
> + cmd = 0;
> + new_old_chain = 0;
> +
> + /* If the command list for this breakpoint includes a statement
> + that deletes breakpoints, we assume that the target may be
> + this breakpoint, so we make a copy of the command list to
> + avoid walking a list that has been deleted. */
> +
> + for (cmd = bs->commands; cmd; cmd = cmd->next)
> + {
> + if (!new_old_chain && bpstat_actions_delete_breakpoints (cmd))
> {
> + cmd = dup_command_lines (cmd);
> + new_old_chain = make_cleanup (cleanup_dup_command_lines, cmd);
> + }
> +
> execute_control_command (cmd);
>
> if (breakpoint_proceeded)
> break;
> - else
> - cmd = cmd->next;
> }
> +
> + if (new_old_chain)
> + {
> + free_command_lines (&cmd);
> + discard_cleanups (new_old_chain);
> + }
> +
> if (breakpoint_proceeded)
> /* The inferior is proceeded by the command; bomb out now.
> The bpstat chain has been blown away by wait_for_inferior.
> @@ -1844,6 +1960,7 @@ top:
> else
> bs->commands = NULL;
> }
> +
>
> executing_breakpoint_commands = 0;
> discard_cleanups (old_chain);
> Index: gdb/defs.h
> ===================================================================
> RCS file: /cvs/src/src/gdb/defs.h,v
> retrieving revision 1.67
> diff -p -u -w -r1.67 defs.h
> --- defs.h 2001/12/06 20:59:11 1.67
> +++ defs.h 2001/12/14 08:13:08
> @@ -839,6 +839,7 @@ struct command_line
> extern struct command_line *read_command_lines (char *, int);
>
> extern void free_command_lines (struct command_line **);
> +extern struct command_line * dup_command_lines (struct command_line *);
>
> /* To continue the execution commands when running gdb asynchronously.
> A continuation structure contains a pointer to a function to be called
> Index: gdb/cli/cli-script.c
> ===================================================================
> RCS file: /cvs/src/src/gdb/cli/cli-script.c,v
> retrieving revision 1.8
> diff -p -u -w -r1.8 cli-script.c
> --- cli-script.c 2001/12/13 22:42:23 1.8
> +++ cli-script.c 2001/12/14 08:13:08
> @@ -1003,6 +1003,59 @@ read_command_lines (char *prompt_arg, in
> return (head);
> }
>
> +/* Duplicate a chain of struct command_line's */
> +
> +struct command_line *
> +dup_command_lines (struct command_line *l)
> +{
> + struct command_line *dup = NULL;
> + register struct command_line *next = NULL;
> +
> +
> + for (; l ; l = l->next)
> + {
> + if (next == NULL)
> + {
> + dup = next = (struct command_line *)
> + xmalloc (sizeof (struct command_line));
> + }
> + else
> + {
> + next->next = (struct command_line *)
> + xmalloc (sizeof (struct command_line));
> +
> + next = next->next;
> + }
> +
> +
> + if (next == NULL)
> + return NULL;
> +
> +
> + next->next = NULL;
> + next->line = xstrdup (l->line);
> + next->control_type = l->control_type;
> + next->body_count = l->body_count;
> +
> +
> + if (l->body_count > 0)
> + {
> + int i;
> + struct command_line **blist = l->body_list;
> +
> + next->body_list =
> + (struct command_line **) xmalloc (sizeof (struct command_line *)
> + * l->body_count);
> +
> + for (i = 0; i < l->body_count; i++, blist++)
> + next->body_list[i] = dup_command_lines (*blist);
> + }
> + }
> +
> + return dup;
> +}
> +
> +
> /* Free a chain of struct command_line's. */
>
> void
>
--
dhoward@redhat.com
gdb engineering