Patch ping

Don Howard
2002-05-13T18:06:06Z

I still need reveiw/approval for the breakpoint portion of this.

--
dhoward@redhat.com
gdb engineering

---------- Forwarded message ----------
Date: Sun, 28 Apr 2002 12:06:11 -0400
From: Fernando Nasser <fnasser@redhat.com>
To: Don Howard <dhoward@redhat.com>
Cc: Andrew Cagney <ac131313@cygnus.com>, Michael Snyder <msnyder@cygnus.com>,
gdb-patches@sources.redhat.com
Subject: Re: [RFA] deleting breakpoints inside of 'commands'

The CLI part is approved. This is somewhat mixed with breakpoints code
(in the breakpoint.c file) so Michael Snyder would have to approve it as
well.

Regards,
Fernando

Don Howard wrote:
>
> I'm revisiting this again, as I've not received feedback the last two
> times that I've reposted it.
>
> This patch addresses a crash that can occur when a breakpoint's command
> list deletes it's own breakpoint. In this solution, breakpoint command
> lists are walked (recursively, so as to examine compound statements and
> user defined commands). If a 'clear' or 'delete' command is found
> anywhere in the definition of the command list, then the command list is
> duplicated and that duplicate is executed. Once execution of the command
> list is complete, the duplicate is freed.
>
> This patch does not address any situation where a user defined command
> deletes itself. (is that even possible? I don't see a way to remove a
> user-defined command, only a way to redefine one.)
>
> This version of contains 2 corrections to
> bpstat_actions_delete_breakpoints()
>
> 1) The call to lookup_cmd() allows unknown commands.
>
> 2) The body of the command is examined regardless of the result of
> lookup_cmd().
>
> Testing on i686 RH 7.2 shows no regressions:
>
> === gdb Summary ===
>
> # of expected passes 8272
> # of unexpected failures 31
> # of unexpected successes 11
> # of expected failures 170
> # of untested testcases 7
> /home/dhoward/work/sources/build/gdb/testsuite/../../gdb/gdb version
> 2002-04-27-cvs -nx
>
> After:
> === gdb Summary ===
>
> # of expected passes 8272
> # of unexpected failures 31
> # of unexpected successes 11
> # of expected failures 170
> # of untested testcases 7
> /home/dhoward/work/sources/rebuild/gdb/testsuite/../../gdb/gdb version
> 2002-04-27-cvs -nx
>
> Comments?
>
> Ok to commit?
>
> 2002-04-27 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 1.74
> diff -p -u -w -r1.74 breakpoint.c
> --- gdb/breakpoint.c 24 Apr 2002 16:28:15 -0000 1.74
> +++ gdb/breakpoint.c 27 Apr 2002 19:18:57 -0000
> @@ -47,6 +47,7 @@
> #include "ui-out.h"
>
> #include "gdb-events.h"
> +#include "cli/cli-decode.h"
>
> /* Prototypes for local functions. */
>
> @@ -1851,6 +1852,100 @@ 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, "", 1, 1);
> +
> + if (ce != NULL)
> + {
> + /* 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
> @@ -1861,7 +1956,6 @@ 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. */
> @@ -1886,16 +1980,37 @@ 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.
> @@ -1905,6 +2020,7 @@ 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 1.88
> diff -p -u -w -r1.88 defs.h
> --- gdb/defs.h 18 Apr 2002 18:08:59 -0000 1.88
> +++ gdb/defs.h 27 Apr 2002 19:18:57 -0000
> @@ -641,6 +641,7 @@ 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 1.12
> diff -p -u -w -r1.12 cli-script.c
> --- gdb/cli/cli-script.c 12 Apr 2002 22:31:23 -0000 1.12
> +++ gdb/cli/cli-script.c 27 Apr 2002 19:18:58 -0000
> @@ -974,6 +974,59 @@ 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

--
Fernando Nasser
Red Hat Canada Ltd. E-Mail: fnasser@redhat.com
2323 Yonge Street, Suite #300
Toronto, Ontario M4P 2C9