Stelian Ionescu sionescu@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