Stelian Ionescu <sione...@cddr.org> writes:
> On Thu, 2012-04-19 at 14:46 +0000, Stas Boukarev wrote:
>> Luís Oliveira <luismbo <at> gmail.com> writes:
>>
>> >
>> > On Thu, Apr 19, 2012 at 2:50 PM, Stelian Ionescu <sionescu <at> cddr.org>
>> wrote:
>> > > (with-foreign-object (p '(:struct timespec) 2)
>> > > (mem-aref p '(:struct timespec) 1))
>> > >
>> > > In order not to break existing code [...]
>> >
>> > Existing code will not have this (:struct foo) syntax because it was
>> > introduced by the libffi merge. (mem-aref p 'timespec 1) should
>> > exhibit backwards-compatible behaviour.
>> Turns out, the problem is not with mem-aref, but with the mem-aref compile-
>> macro. It binds *parse-bare-structs-as-pointers* to T, whereas mem-aref
>> function
>> doesn't, this affects the result of foreign-type-size.
>
> Actually it's mem-aref that should bind *parse-bare-structs-as-pointers*
> to T, so I pushed the fix
This breaks it.
(cffi:defcstruct foo
(a :short)
(b :short))
;; After binding *parse-bare-structs-as-pointers* to T in the mem-aref function:
(cffi:with-foreign-object
(var 'foo 20)
(let ((type 'foo))
(cffi:mem-aref var type)))
;; new cffi => #.(SB-SYS:INT-SAP #X00000000)
;; old cffi and new with a constant type return an expected address
;; Previous problems I originally described:
(cffi:with-foreign-object (var 'foo 2)
(- (cffi-sys:pointer-address (cffi:mem-aref var 'foo 1))
(cffi-sys:pointer-address (cffi:mem-aref var 'foo 0))))
;; old cffi => 4
;; new cffi => 8
;; With mem-aptr works as expected:
(cffi:with-foreign-object (var 'foo 2)
(- (cffi-sys:pointer-address (cffi:mem-aptr var 'foo 1))
(cffi-sys:pointer-address (cffi:mem-aptr var 'foo 0))))
;; new cffi => 4
--
With best regards, Stas.
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