path: root/gi/pygi-signal-closure.c

/* -*- mode: C; c-basic-offset: 4; indent-tabs-mode: nil; -*- */
/*
 * Copyright (c) 2011  Laszlo Pandy <lpandy@src.gnome.org>
 *
 * This library is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * This library is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this library; if not, see <http://www.gnu.org/licenses/>.
 */

#include "pygi-signal-closure.h"
#include "pygi-value.h"
#include "pygi-argument.h"
#include "pygi-boxed.h"

static GISignalInfo *
_pygi_lookup_signal_from_g_type (GType g_type,
                                 const gchar *signal_name)
{
    GIRepository *repository;
    GIBaseInfo *info;
    GISignalInfo *signal_info = NULL;

    repository = g_irepository_get_default();
    info = g_irepository_find_by_gtype (repository, g_type);
    if (info == NULL)
        return NULL;

    if (GI_IS_OBJECT_INFO (info))
        signal_info = g_object_info_find_signal ((GIObjectInfo *) info,
                                                 signal_name);
    else if (GI_IS_INTERFACE_INFO (info))
        signal_info = g_interface_info_find_signal ((GIInterfaceInfo *) info,
                                                    signal_name);

    g_base_info_unref (info);
    return signal_info;
}

static void
pygi_signal_closure_invalidate(gpointer data,
                               GClosure *closure)
{
    PyGClosure *pc = (PyGClosure *)closure;
    PyGILState_STATE state;

    state = PyGILState_Ensure();
    Py_XDECREF(pc->callback);
    Py_XDECREF(pc->extra_args);
    Py_XDECREF(pc->swap_data);
    PyGILState_Release(state);

    pc->callback = NULL;
    pc->extra_args = NULL;
    pc->swap_data = NULL;

    g_base_info_unref (((PyGISignalClosure *) pc)->signal_info);
    ((PyGISignalClosure *) pc)->signal_info = NULL;
}

static void
pygi_signal_closure_marshal(GClosure *closure,
                            GValue *return_value,
                            guint n_param_values,
                            const GValue *param_values,
                            gpointer invocation_hint,
                            gpointer marshal_data)
{
    PyGILState_STATE state;
    PyGClosure *pc = (PyGClosure *)closure;
    PyObject *params, *ret = NULL;
    guint i;
    GISignalInfo *signal_info;
    gint n_sig_info_args;
    gint sig_info_highest_arg;
    GSList *list_item = NULL;
    GSList *pass_by_ref_structs = NULL;

    state = PyGILState_Ensure();

    signal_info = ((PyGISignalClosure *)closure)->signal_info;
    n_sig_info_args = g_callable_info_get_n_args(signal_info);
    g_assert_cmpint (n_sig_info_args, >=, 0);
    /* the first argument to a signal callback is instance,
       but instance is not counted in the introspection data */
    sig_info_highest_arg = n_sig_info_args + 1;
    g_assert_cmpint(sig_info_highest_arg, ==, n_param_values);

    /* construct Python tuple for the parameter values */
    params = PyTuple_New(n_param_values);
    for (i = 0; i < n_param_values; i++) {
        /* swap in a different initial data for connect_object() */
        if (i == 0 && G_CCLOSURE_SWAP_DATA(closure)) {
            g_return_if_fail(pc->swap_data != NULL);
            Py_INCREF(pc->swap_data);
            PyTuple_SetItem(params, 0, pc->swap_data);

        } else if (i == 0) {
            PyObject *item = pyg_value_as_pyobject(&param_values[i], FALSE);

            if (!item) {
                goto out;
            }
            PyTuple_SetItem(params, i, item);

        } else if (i < (guint)sig_info_highest_arg) {
            GIArgInfo arg_info;
            GITypeInfo type_info;
            GITypeTag type_tag;
            GIArgument arg = { 0, };
            PyObject *item = NULL;
            gboolean free_array = FALSE;
            gboolean pass_struct_by_ref = FALSE;

            g_callable_info_load_arg(signal_info, i - 1, &arg_info);
            g_arg_info_load_type(&arg_info, &type_info);

            arg = _pygi_argument_from_g_value(&param_values[i], &type_info);

            type_tag = g_type_info_get_tag (&type_info);
            if (type_tag == GI_TYPE_TAG_ARRAY) {
                /* Skip the self argument of param_values */
                arg.v_pointer = _pygi_argument_to_array (&arg,
                                                         _pygi_argument_array_length_marshal,
                                                         (void *)(param_values + 1),
                                                         signal_info,
                                                         &type_info,
                                                         &free_array);
            }

            /* Hack to ensure struct arguments are passed-by-reference allowing
             * callback implementors to modify the struct values. This is needed
             * for keeping backwards compatibility and should be removed in future
             * versions which support signal output arguments as return values.
             * See: https://bugzilla.gnome.org/show_bug.cgi?id=735486
             *
             * Note the logic here must match the logic path taken in _pygi_argument_to_object.
             */
            if (type_tag == GI_TYPE_TAG_INTERFACE) {
                GIBaseInfo *info = g_type_info_get_interface (&type_info);
                GIInfoType info_type = g_base_info_get_type (info);

                if (info_type == GI_INFO_TYPE_STRUCT ||
                        info_type == GI_INFO_TYPE_BOXED ||
                        info_type == GI_INFO_TYPE_UNION) {

                    GType gtype = g_registered_type_info_get_g_type ((GIRegisteredTypeInfo *) info);
                    gboolean is_foreign = (info_type == GI_INFO_TYPE_STRUCT) &&
                                          (g_struct_info_is_foreign ((GIStructInfo *) info));

                    if (!is_foreign && !g_type_is_a (gtype, G_TYPE_VALUE) &&
                            g_type_is_a (gtype, G_TYPE_BOXED)) {
                        pass_struct_by_ref = TRUE;
                    }
                }

                g_base_info_unref (info);
            }

            if (pass_struct_by_ref) {
                /* transfer everything will ensure the struct is not copied when wrapped. */
                item = _pygi_argument_to_object (&arg, &type_info, GI_TRANSFER_EVERYTHING);
                if (item && PyObject_IsInstance (item, (PyObject *) &PyGIBoxed_Type)) {
                    ((PyGBoxed *)item)->free_on_dealloc = FALSE;
                    pass_by_ref_structs = g_slist_prepend (pass_by_ref_structs, item);
                }

            } else {
                item = _pygi_argument_to_object (&arg, &type_info, GI_TRANSFER_NOTHING);
            }

            if (free_array) {
                g_array_free (arg.v_pointer, FALSE);
            }

            if (item == NULL) {
                PyErr_Print ();
                goto out;
            }
            PyTuple_SetItem(params, i, item);
        }
    }
    /* params passed to function may have extra arguments */
    if (pc->extra_args) {
        PyObject *tuple = params;
        params = PySequence_Concat(tuple, pc->extra_args);
        Py_DECREF(tuple);
    }
    ret = PyObject_CallObject(pc->callback, params);
    if (ret == NULL) {
        if (pc->exception_handler)
            pc->exception_handler(return_value, n_param_values, param_values);
        else
            PyErr_Print();
        goto out;
    }

    if (G_IS_VALUE(return_value) && pyg_value_from_pyobject(return_value, ret) != 0) {
        PyErr_SetString(PyExc_TypeError,
                        "can't convert return value to desired type");

        if (pc->exception_handler)
            pc->exception_handler(return_value, n_param_values, param_values);
        else
            PyErr_Print();
    }
    Py_DECREF(ret);

    /* Run through the list of structs which have been passed by reference and
     * check if they are being held longer than the duration of the callback
     * execution. This is determined if the ref count is greater than 1.
     * A single ref is held by the argument list and any more would mean the callback
     * stored a ref somewhere else. In this case we make an internal copy of
     * the boxed struct so Python can own the memory to it.
     */
    list_item = pass_by_ref_structs;
    while (list_item) {
        PyObject *item = list_item->data;
        if (Py_REFCNT (item) > 1) {
            pygi_boxed_copy_in_place ((PyGIBoxed *)item);
        }
        list_item = g_slist_next (list_item);
    }

 out:
    g_slist_free (pass_by_ref_structs);
    Py_DECREF(params);
    PyGILState_Release(state);
}

GClosure *
pygi_signal_closure_new (PyGObject *instance,
                         GType g_type,
                         const gchar *signal_name,
                         PyObject *callback,
                         PyObject *extra_args,
                         PyObject *swap_data)
{
    GClosure *closure = NULL;
    PyGISignalClosure *pygi_closure = NULL;
    GISignalInfo *signal_info = NULL;

    g_return_val_if_fail(callback != NULL, NULL);

    signal_info = _pygi_lookup_signal_from_g_type (g_type, signal_name);
    if (signal_info == NULL)
        return NULL;

    closure = g_closure_new_simple(sizeof(PyGISignalClosure), NULL);
    g_closure_add_invalidate_notifier(closure, NULL, pygi_signal_closure_invalidate);
    g_closure_set_marshal(closure, pygi_signal_closure_marshal);

    pygi_closure = (PyGISignalClosure *)closure;

    pygi_closure->signal_info = signal_info;
    Py_INCREF(callback);
    pygi_closure->pyg_closure.callback = callback;

    if (extra_args != NULL && extra_args != Py_None) {
        Py_INCREF(extra_args);
        if (!PyTuple_Check(extra_args)) {
            PyObject *tmp = PyTuple_New(1);
            PyTuple_SetItem(tmp, 0, extra_args);
            extra_args = tmp;
        }
        pygi_closure->pyg_closure.extra_args = extra_args;
    }
    if (swap_data) {
        Py_INCREF(swap_data);
        pygi_closure->pyg_closure.swap_data = swap_data;
        closure->derivative_flag = TRUE;
    }

    return closure;
}