binding of a C struct

[PICCA Frederic-Emmanuel <frederic-emmanuel picca synchrotron-soleil fr>]

Hello,

here my C struct


typedef struct _HklQuaternion HklQuaternion;

struct _HklQuaternion
{
        double data[4];
};


I want to annotate a method which return an HklQuaternion

HklQuaternion hkl_geometry_sample_rotation_get(const HklGeometry *self, const HklSample *sample);

So I have this


/**
 * hkl_geometry_sample_rotation_get:
 * @self: the self @HklGeometry@
 * @sample: the rotated sample.
 *
 * return the rotation part of the given sample in the laboratory basis.
 *
 * Returns: the rotation express as a quaternion.
 **/
HklQuaternion hkl_geometry_sample_rotation_get(const HklGeometry *self,
                                               const HklSample *sample)
{
        return darray_item(self->holders, 0)->q;
}


this produce in the gir


    <record name="Quaternion"
            c:type="HklQuaternion"
            glib:type-name="HklQuaternion"
            glib:get-type="hkl_quaternion_get_type"
            c:symbol-prefix="quaternion">
      <field name="data" writable="1">
        <array zero-terminated="0" c:type="double" fixed-size="4">
          <type name="gdouble" c:type="double"/>
        </array>
      </field>
    </record>


and

      <method name="sample_rotation_get"
              c:identifier="hkl_geometry_sample_rotation_get">
        <doc xml:space="preserve">return the rotation part of the given sample in the laboratory basis.</doc>
        <return-value transfer-ownership="full">
          <doc xml:space="preserve">the rotation express as a quaternion.</doc>
          <type name="Quaternion" c:type="HklQuaternion"/>
        </return-value>
        <parameters>
          <instance-parameter name="self" transfer-ownership="none">
            <doc xml:space="preserve">the self @HklGeometry@</doc>
            <type name="Geometry" c:type="const HklGeometry*"/>
          </instance-parameter>
          <parameter name="sample" transfer-ownership="none">
            <doc xml:space="preserve">the rotated sample.</doc>
            <type name="Sample" c:type="const HklSample*"/>
          </parameter>
        </parameters>
      </method>

the hkl_quaternion_get_type method is here



#define HKL_TYPE(type, camelcase_type, copy, free)                      \
        GType hkl_## type ## _get_type (void) {                         \
                static volatile gsize hkl_type_id__volatile = 0;        \
                if (g_once_init_enter (&hkl_type_id__volatile)) {       \
                        GType hkl_type_id;                              \
                        hkl_type_id = g_boxed_type_register_static (    \
                                #camelcase_type,                        \
                                (GBoxedCopyFunc) copy,                  \
                                (GBoxedFreeFunc) free);                 \
                        g_once_init_leave (&hkl_type_id__volatile, hkl_type_id); \
                }                                                       \
                return hkl_type_id__volatile;                           \
        }

HKL_TYPE(quaternion, HklQuaternion, hkl_quaternion_dup, hkl_quaternion_free);

BUT

When I I using this from python I get a segfault.


#0  0xb681b5ab in hkl_geometry_sample_rotation_get (self=0x872a740, sample=0xb6bfb119 <g_private_get+9>) at 
hkl-geometry.c:807
#1  0xb6d8ba82 in ffi_call_SYSV () from /usr/lib/i386-linux-gnu/libffi.so.6
#2  0xb6d8b556 in ffi_call () from /usr/lib/i386-linux-gnu/libffi.so.6
#3  0xb6d5a6df in ?? () from /usr/lib/python2.7/dist-packages/gi/_gi.so
#4  0xb6d5b214 in ?? () from /usr/lib/python2.7/dist-packages/gi/_gi.so
#5  0xb6d5c160 in ?? () from /usr/lib/python2.7/dist-packages/gi/_gi.so
#6  0xb6d5aeb0 in ?? () from /usr/lib/python2.7/dist-packages/gi/_gi.so
#7  0xb6d5aef1 in ?? () from /usr/lib/python2.7/dist-packages/gi/_gi.so
#8  0xb6d4ed1e in ?? () from /usr/lib/python2.7/dist-packages/gi/_gi.so
#9  0x08107d5f in PyObject_Call (kw=<optimized out>, arg=<optimized out>, func=<optimized out>) at 
../Objects/abstract.c:2529
#10 do_call (nk=<optimized out>, na=<optimized out>, pp_stack=<optimized out>, func=<optimized out>) at 
../Python/ceval.c:4251
#11 call_function (oparg=<optimized out>, pp_stack=<optimized out>) at ../Python/ceval.c:4056
#12 PyEval_EvalFrameEx () at ../Python/ceval.c:2679
#13 0x081078bb in fast_function (nk=<optimized out>, na=<optimized out>, n=<optimized out>, 
pp_stack=<optimized out>, func=<optimized out>) at ../Python/ceval.c:4119
#14 call_function (oparg=<optimized out>, pp_stack=<optimized out>) at ../Python/ceval.c:4054
#15 PyEval_EvalFrameEx () at ../Python/ceval.c:2679


so my question is what is the right way to expose a struc in a binding with gobject.

thanks for your help

Frédéric