I think that changing `_pointer` to `_DWORD` can't be the real answer, since `_pointer` is at least as large as `_DWORD`.
But I agree that you should use `malloc`, and you should also supply 'atomic-interior: (malloc _DWORD 'atomic-interior) The 'atomic-interior flag ensures that the allocated memory does not move during an invocation of the callback. Along similar lines, I think you need to add #:malloc-mode 'atomic-interior to the declaration of `_CMN_ERROR`. You may need to copy the `filter` argument into non-moving memory, but that's probably not an issue if it's always "". At Mon, 15 Sep 2014 11:07:52 +0700 (NOVT), "Evgeny Odegov" wrote: > More complete example: > http://pasterack.org/pastes/25901 > > I guess I've found reason of the problem. > > I think the problem was in that line: > (define lpdwItems (make-bytes (ctype-sizeof _pointer) 0)) > > I've changed it to: > (define lpdwItems (make-bytes (ctype-sizeof _DWORD) 0)) > > There is no visible problems now, but I doubt that applying `make-bytes' > here is right. > > Should I use `malloc' in such cases? > > > Anyway, sorry for the noise. > > > > My best guess is that it's an issue with memory management, because > > memory management gets a lot trickier when you call a function that can > > call back into Racket. A GC can happen during the callback, and > > therefore during the dynamic extent of the foreign-function call, which > > can move arguments that were passed to the foreign function, for example. > > > > Would it be possible to provide a complete example? > > > > At Sat, 13 Sep 2014 22:45:28 +0700 (NOVT), "Evgeny Odegov" wrote: > >> Oh, I'm wrong. The last code is not equivalent to initial. > >> The equivalent code has this problem: > >> > >> (define result (make-hash)) > >> (define big-list (list)) > >> (define (callback dwTextID lpszInfoText lpvUser) > >> (if (equal? lpszInfoText "") > >> (set! big-list (append big-list (list dwTextID))) > >> (hash-update! result > >> lpszInfoText > >> (lambda (id-lst) > >> (define v (list dwTextID)) > >> (append id-lst v)) > >> '())) > >> #t) > >> > >> > >> The code with `cons' instead `append' works fine: > >> > >> (define result (make-hash)) > >> (define (callback dwTextID lpszInfoText lpvUser) > >> (hash-update! result > >> lpszInfoText > >> (lambda (id-lst) > >> (define new-id-lst (cons dwTextID id-lst)) > >> (unless (list? new-id-lst) > >> > >> (error "~v" new-id-lst)) > >> new-id-lst) > >> '()) > >> #t) > >> > >> > >> > >> > >> ____________________ > >> Racket Users list: > >> http://lists.racket-lang.org/users > > ____________________ Racket Users list: http://lists.racket-lang.org/users
