* Elf and Dwarf from DwflModule life times?
@ 2007-07-12 15:29 Andrew Cagney
2007-07-12 20:32 ` Roland McGrath
0 siblings, 1 reply; 4+ messages in thread
From: Andrew Cagney @ 2007-07-12 15:29 UTC (permalink / raw)
To: Roland McGrath; +Cc: frysk
Roland,
I'm trying to understand the lifetime of the Elf and Dwarf objects
returned by the dwfl_module_getelf and dwfl_module_getdwarf methods.
Is there anything explaining this, in the header, say?
Andrew
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Elf and Dwarf from DwflModule life times?
2007-07-12 15:29 Elf and Dwarf from DwflModule life times? Andrew Cagney
@ 2007-07-12 20:32 ` Roland McGrath
2007-07-12 21:37 ` Andrew Cagney
0 siblings, 1 reply; 4+ messages in thread
From: Roland McGrath @ 2007-07-12 20:32 UTC (permalink / raw)
To: Andrew Cagney; +Cc: frysk
> I'm trying to understand the lifetime of the Elf and Dwarf objects
> returned by the dwfl_module_getelf and dwfl_module_getdwarf methods.
Everything you get from libdwfl about a particular module is live while
that module is live. You have to assume it all gets freed and becomes
invalid pointers when the module is removed. A module gets removed at the
end of a reporting pass that did not report it, when your dwfl_report_end
call will make callbacks to its REMOVED argument. (And of course all the
modules go away at dwfl_end.)
> Is there anything explaining this, in the header, say?
I don't think it is very clear anywhere. (I always figured the details of
the reporting stuff might change a little when nontrivial users came along.)
There is a longer-term plan for caching and sharing that will complicate
the situation with the potential for options other than eagerly dropping
everything when a module dies. (It may soon be about time for that work.)
But the conservative rules for callers now will continue to be safe.
Thanks,
Roland
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Elf and Dwarf from DwflModule life times?
2007-07-12 20:32 ` Roland McGrath
@ 2007-07-12 21:37 ` Andrew Cagney
2007-07-12 22:24 ` Roland McGrath
0 siblings, 1 reply; 4+ messages in thread
From: Andrew Cagney @ 2007-07-12 21:37 UTC (permalink / raw)
To: Roland McGrath; +Cc: frysk
Roland McGrath wrote:
>> I'm trying to understand the lifetime of the Elf and Dwarf objects
>> returned by the dwfl_module_getelf and dwfl_module_getdwarf methods.
>>
>
> Everything you get from libdwfl about a particular module is live while
> that module is live. You have to assume it all gets freed and becomes
> invalid pointers when the module is removed. A module gets removed at the
> end of a reporting pass that did not report it, when your dwfl_report_end
> call will make callbacks to its REMOVED argument. (And of course all the
> modules go away at dwfl_end.)
>
>
Ok, thanks.
I just figured out that "fildes" is copied (not duped) when elf_clone is
called; we'll need to be careful there as well.
Andrew
>> Is there anything explaining this, in the header, say?
>>
>
> I don't think it is very clear anywhere. (I always figured the details of
> the reporting stuff might change a little when nontrivial users came along.)
>
> There is a longer-term plan for caching and sharing that will complicate
> the situation with the potential for options other than eagerly dropping
> everything when a module dies. (It may soon be about time for that work.)
> But the conservative rules for callers now will continue to be safe.
>
>
> Thanks,
> Roland
>
>
>
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: Elf and Dwarf from DwflModule life times?
2007-07-12 21:37 ` Andrew Cagney
@ 2007-07-12 22:24 ` Roland McGrath
0 siblings, 0 replies; 4+ messages in thread
From: Roland McGrath @ 2007-07-12 22:24 UTC (permalink / raw)
To: Andrew Cagney; +Cc: frysk
> I just figured out that "fildes" is copied (not duped) when elf_clone is
> called; we'll need to be careful there as well.
I can't imagine why you would ever use elf_clone. Anyway, yes, libelf does
nothing special to manage file descriptors.
libdwfl manages the file descriptors.
^ permalink raw reply [flat|nested] 4+ messages in thread
end of thread, other threads:[~2007-07-12 22:24 UTC | newest]
Thread overview: 4+ messages (download: mbox.gz / follow: Atom feed)
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2007-07-12 15:29 Elf and Dwarf from DwflModule life times? Andrew Cagney
2007-07-12 20:32 ` Roland McGrath
2007-07-12 21:37 ` Andrew Cagney
2007-07-12 22:24 ` Roland McGrath
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