[cffi-devel] Next release of CFFI with cffi-libffi

[Stas Boukarev]

Stelian Ionescu <sionescu at 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.