[julia-users] c struct to Type?

[Andreas Lobinger]

Hello colleagues,

i'm trying to get further interfacing to libcairo, but i somehow run into 
problems for matching c structures.

My example
using Cairo

i = CairoImageSurface(100,100,Cairo.FORMAT_RGB24)
cr = CairoContext(i)
select_font_face (cr, "Sans", Cairo.FONT_SLANT_NORMAL,
                         Cairo.FONT_WEIGHT_BOLD);
set_font_size (cr, 90.0);
move_to (cr, 10.0, 135.0);
text_path (cr, "5");

# typedef struct cairo_path {
#     cairo_status_t status;
#     cairo_path_data_t *data;
#     int num_data;
# } cairo_path_t;

type Pdata 
    status::Cairo.status_t    
    data::Ptr{Uint32}
    num_data::Uint32
end

function pdata_copy_path(ctx::CairoContext)
    ccall((:cairo_copy_path, Cairo._jl_libcairo),
                    Pdata, (Ptr{Void},),ctx.ptr)
end    

p = pdata_copy_path(cr);

returns, here:

lobi@orange4:~/juliarepo$ ../julia/julia 
               _
   _       _ _(_)_     |  A fresh approach to technical computing
  (_)     | (_) (_)    |  Documentation: http://docs.julialang.org
   _ _   _| |_  __ _   |  Type "help()" for help.
  | | | | | | |/ _` |  |
  | | |_| | | | (_| |  |  Version 0.3.9 (2015-05-30 11:24 UTC)
 _/ |\__'_|_|_|\__'_|  |  
|__/                   |  x86_64-linux-gnu

julia> include("cairop2.jl")
Pdata(87413648,Ptr{Uint32} @0x000000000000004f,0x0387dd54)

julia> 

which i do not consider correct, as i know the cairo status (first entry in 
Pdata) should be 0, the following pointer to data is the number of entries 
(i have a correctly working c program for the same example).

I spare you the details, but the same code run with a v0.4.0-dev+5208 
segfaults...

How do i get my 3 entries in the path data structure (see cairo.h 
definition in comment inline) correct (and version independent)?

Wishing a happy day,
         Andreas