On Sun, Dec 10, 2017 at 07:22:55AM -0800, Matt Wette wrote:
> 
> > On Dec 9, 2017, at 10:06 AM, pelzflorian (Florian Pelz) <pelzflorian@pelzflorian.de> wrote:
> > (define xerror-handler-struct
> >  (make-struct-po_xerror_handler)) ; TODO SET HANDLERS:
> > ;; […]
> > 
> 
> First of all, FFI helper + Guile can't deal with this pattern: using varargs function 
> members in structs.  This would require things like `va_arg' in libffi and Guile.  I 
> have posted a request on the libffi dev site.  Your example also brought up some gaps
> in the ffi helper.

Thank you.  I’m sorry to say that it did not work.

Actually it is not the “struct po_error_handler” but the
“struct po_xerror_handler” which I need.  I believe the “struct
po_error_handler” is not used anymore in current Gettext but I am not
sure.  varargs are not needed for “struct po_xerror_handler” (even
though support for them is desirable in general).

Hmm I tried mostly the same as you propose before for the xerror
handler and it did not work: fh-object-set! apparently did not have
any effect, i.e. a subsequent fh-object-ref returned 0 and on error
the callback handler function was called at address 0, causing a
SIGSEGV.

Either way, I tried your code for “struct po_error_handler” and put it
in my dot.ffi to see if it works.


> I think I may have a workaround for you, though.  Try to add code
> like the following to your dot-ffi file.  In functions calls that want a error handler
> specified use std-po-error-handler.
> 
> 
> (define-ffi-module (gettext-po)
>   #:include '("gettext-po.h")
>   #:library '("libgettextpo"))
> 
> (define-public std-po-error-handler
>   (let* ((error
> 	  (lambda (status errnum format)
> 	    (simple-format #t "~A\n" (ffi:pointer->string format))))
> 	 (error-p
> 	  (ffi:procedure->pointer ffi:void error (list ffi:int ffi:int '*)))
> 	 ;;
> 	 (error_at_line
> 	  (lambda (status errnum filename lineno format)
> 	    (simple-format #t "~A\n" (ffi:pointer->string format))))
> 	 (error_at_line-p
> 	  (ffi:procedure->pointer ffi:void error_at_line
> 				  (list ffi:int ffi:int '* ffi:int '*)))
> 	 ;;
> 	 (multiline_warning
> 	  (lambda (prefix message)
> 	    (simple-format #t "~A ~A\n"
> 			   (ffi:pointer->string prefix)
> 			   (ffi:pointer->string message))))
> 	 (multiline_warning-p
> 	  (ffi:procedure->pointer ffi:void multiline_warning (list '* '*)))
> 	 ;;
> 	 (multiline_error
> 	  (lambda (prefix message)
> 	    (simple-format #t "~A ~A\n" prefix message)))
> 	 (multiline_error-p
> 	  (ffi:procedure->pointer ffi:void multiline_error (list '* '*)))
> 	 ;;
> 	 (eh-struct (make-struct-po_error_handler)))
>     
>     (fh-object-set! eh-struct 'error error-p)


I inserted an

    (display (fh-object-ref eh-struct 'error)) (newline)

at this point at this point in the dot.ffi file.  Then when I ran

(use-modules (gettext-po))

from the REPL it printed 0, so presumably this does not work either.
It seems like the same issue.

>     (fh-object-set! eh-struct 'error_at_line error_at_line-p)
>     (fh-object-set! eh-struct 'multiline_warning multiline_warning-p)
>     (fh-object-set! eh-struct 'multiline_error multiline_error-p)
>     ;;
>     (make-po_error_handler_t
>      (ffi:pointer-address
>       ((fht-unwrap struct-po_error_handler*)
>        (pointer-to eh-struct))))))
> 



By the way, what I forgot to mention is that I needed to replace

#include <stdlib.h>

in the gettext-po.h header file by

typedef long size_t;

otherwise “guild compile-ffi gettext-po.ffi” would fail with the error
message

ffi-help: WARNING: the FFI helper is experimental
(unknown):1: not found: "gnu/stubs-32.h"
compile-ffi: parse failed

So this change is needed in order to reproduce my issue.

Regards,
Florian