* A question about struct coding_system
@ 2011-11-21 16:13 Dmitry Antipov
2011-11-21 16:55 ` Andreas Schwab
2011-11-21 17:47 ` Stefan Monnier
0 siblings, 2 replies; 5+ messages in thread
From: Dmitry Antipov @ 2011-11-21 16:13 UTC (permalink / raw
To: emacs-devel
At a first glance, struct coding_system should be a vector-like
object with src_object and dst_object at the beginning. But it
isn't, and it looks like that src_object and dst_object are never
marked directly. Thus, it should be guaranteed that, for any
coding_system, objects referenced by src_object and dst_object
are always reachable from another live objects. But I can't
find any code that takes care about this, so I don't understand
why and how it works at all :-(.
Dmitry
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: A question about struct coding_system
2011-11-21 16:13 A question about struct coding_system Dmitry Antipov
@ 2011-11-21 16:55 ` Andreas Schwab
2011-11-21 20:22 ` Stefan Monnier
2011-11-21 17:47 ` Stefan Monnier
1 sibling, 1 reply; 5+ messages in thread
From: Andreas Schwab @ 2011-11-21 16:55 UTC (permalink / raw
To: Dmitry Antipov; +Cc: emacs-devel
Dmitry Antipov <antipov@mvista.com> writes:
> At a first glance, struct coding_system should be a vector-like
> object with src_object and dst_object at the beginning. But it
> isn't, and it looks like that src_object and dst_object are never
> marked directly. Thus, it should be guaranteed that, for any
> coding_system, objects referenced by src_object and dst_object
> are always reachable from another live objects. But I can't
> find any code that takes care about this, so I don't understand
> why and how it works at all :-(.
It's generally the duty of the caller to protect the object. If it is a
buffer it should be the current buffer. If it is passed in from Lisp it
is already protected. Other cases should be explicitly protected.
Andreas.
--
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5
"And now for something completely different."
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: A question about struct coding_system
2011-11-21 16:13 A question about struct coding_system Dmitry Antipov
2011-11-21 16:55 ` Andreas Schwab
@ 2011-11-21 17:47 ` Stefan Monnier
1 sibling, 0 replies; 5+ messages in thread
From: Stefan Monnier @ 2011-11-21 17:47 UTC (permalink / raw
To: Dmitry Antipov; +Cc: emacs-devel
> At a first glance, struct coding_system should be a vector-like
> object with src_object and dst_object at the beginning. But it
> isn't, and it looks like that src_object and dst_object are never
> marked directly. Thus, it should be guaranteed that, for any
> coding_system, objects referenced by src_object and dst_object
> are always reachable from another live objects. But I can't
> find any code that takes care about this, so I don't understand
> why and how it works at all :-(.
It may very well work just by accident (the "global" coding_system
objects have src/dst_object fields that contain globally live objects
such as nil, while the others point to objects that are also reachable
via some local variable).
Stefan
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: A question about struct coding_system
2011-11-21 16:55 ` Andreas Schwab
@ 2011-11-21 20:22 ` Stefan Monnier
2011-11-21 20:32 ` Andreas Schwab
0 siblings, 1 reply; 5+ messages in thread
From: Stefan Monnier @ 2011-11-21 20:22 UTC (permalink / raw
To: Andreas Schwab; +Cc: Dmitry Antipov, emacs-devel
> It's generally the duty of the caller to protect the object.
No, Emacs's C code generally puts the burden on the callee rather than
the caller (with a few exceptions like Ffuncall).
Stefan
^ permalink raw reply [flat|nested] 5+ messages in thread
* Re: A question about struct coding_system
2011-11-21 20:22 ` Stefan Monnier
@ 2011-11-21 20:32 ` Andreas Schwab
0 siblings, 0 replies; 5+ messages in thread
From: Andreas Schwab @ 2011-11-21 20:32 UTC (permalink / raw
To: Stefan Monnier; +Cc: Dmitry Antipov, emacs-devel
Stefan Monnier <monnier@iro.umontreal.ca> writes:
>> It's generally the duty of the caller to protect the object.
>
> No, Emacs's C code generally puts the burden on the callee rather than
> the caller (with a few exceptions like Ffuncall).
I'm talking only about the caller of (en|de)code_coding_*.
Andreas.
--
Andreas Schwab, schwab@linux-m68k.org
GPG Key fingerprint = 58CA 54C7 6D53 942B 1756 01D3 44D5 214B 8276 4ED5
"And now for something completely different."
^ permalink raw reply [flat|nested] 5+ messages in thread
end of thread, other threads:[~2011-11-21 20:32 UTC | newest]
Thread overview: 5+ messages (download: mbox.gz follow: Atom feed
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2011-11-21 16:13 A question about struct coding_system Dmitry Antipov
2011-11-21 16:55 ` Andreas Schwab
2011-11-21 20:22 ` Stefan Monnier
2011-11-21 20:32 ` Andreas Schwab
2011-11-21 17:47 ` Stefan Monnier
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