From: Jim Blandy <jimb@redhat.com>
To: Daniel Jacobowitz <drow@mvista.com>
Cc: gdb@sources.redhat.com
Subject: Re: Macro code crasher on re-run
Date: Mon, 03 Nov 2003 04:48:00 -0000 [thread overview]
Message-ID: <vt2ism2xdkq.fsf@zenia.home> (raw)
In-Reply-To: <20031103040751.GA30979@nevyn.them.org>
Daniel Jacobowitz <drow@mvista.com> writes:
> There's a bug in default_macro_scope.
Only one?!? :)
> 97
> 98 /* If all else fails, fall back to the current listing position. */
> 99 else
> 100 {
> 101 /* Don't call select_source_symtab here. That can raise an
> 102 error if symbols aren't loaded, but GDB calls the expression
> 103 evaluator in all sorts of contexts.
> 104
> 105 For example, commands like `set width' call the expression
> 106 evaluator to evaluate their numeric arguments. If the
> 107 current language is C, then that may call this function to
> 108 choose a scope for macro expansion. If you don't have any
> 109 symbol files loaded, then get_current_or_default would raise an
> 110 error. But `set width' shouldn't raise an error just because
> 111 it can't decide which scope to macro-expand its argument in. */
> 112 struct symtab_and_line cursal =
> 113 get_current_source_symtab_and_line ();
> 114
> 115 sal.symtab = cursal.symtab;
> 116 sal.line = cursal.line;
> 117 }
>
> So we initialize just the symtab and line pointers.
> 118
> 119 return sal_macro_scope (sal);
> 120 }
>
>
> 39 if (! sal.symtab
> 40 || ! sal.symtab->macro_table)
> 41 return 0;
>
> Oops, uninitialized memory read. That else case can't work; Jim, should we
> just return 0 from default_macro_scope if the target isn't running, or
> is there a function I don't see somewhere to find the macrotab and
> initialize the rest of the symtab? Should it be "sal = cursal"?
I don't follow. All default_macro_scope's callers check for null
return; it's documented to return zero at times. So you must be
talking about that code in sal_macro_scope itself. Line 39 refers to
sal.symtab, initialized by line 115, so you must be talking about line
40. But sal.symtab must be non-zero, or else we wouldn't reach the
right operand of the ||.
Or should I sleep and try again?
next prev parent reply other threads:[~2003-11-03 4:48 UTC|newest]
Thread overview: 12+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-11-03 4:07 Daniel Jacobowitz
2003-11-03 4:48 ` Jim Blandy [this message]
2003-11-03 4:56 ` Daniel Jacobowitz
2003-11-03 21:00 ` Jim Blandy
2003-11-03 21:04 ` Daniel Jacobowitz
2003-11-03 21:34 ` Jim Blandy
2003-11-03 21:37 ` Daniel Jacobowitz
2003-11-03 23:51 ` Jim Blandy
2003-11-07 16:29 ` Daniel Jacobowitz
2003-11-10 23:38 ` Jim Blandy
2003-11-03 21:46 ` David Carlton
2003-11-03 22:01 ` Andrew Cagney
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=vt2ism2xdkq.fsf@zenia.home \
--to=jimb@redhat.com \
--cc=drow@mvista.com \
--cc=gdb@sources.redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for read-only IMAP folder(s) and NNTP newsgroup(s).