gi/pygi-signal-closure.c

   1 /* -*- mode: C; c-basic-offset: 4; indent-tabs-mode: nil; -*- */
   2 /*
   3  * Copyright (c) 2011  Laszlo Pandy <lpandy@src.gnome.org>
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2.1 of the License, or (at your option) any later version.
   9  *
  10  * This library is distributed in the hope that it will be useful,
  11  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  12  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  13  * Lesser General Public License for more details.
  14  *
  15  * You should have received a copy of the GNU Lesser General Public
  16  * License along with this library; if not, see <http://www.gnu.org/licenses/>.
  17  */
  18
  19 #include "pygi-private.h"
  20 #include "pygi-value.h"
  21
  22 static GISignalInfo *
  23 _pygi_lookup_signal_from_g_type (GType g_type,
  24                                  const gchar *signal_name)
  25 {
  26     GIRepository *repository;
  27     GIBaseInfo *info;
  28     GISignalInfo *signal_info = NULL;
  29
  30     repository = g_irepository_get_default();
  31     info = g_irepository_find_by_gtype (repository, g_type);
  32     if (info == NULL)
  33         return NULL;
  34
  35     if (GI_IS_OBJECT_INFO (info))
  36         signal_info = g_object_info_find_signal ((GIObjectInfo *) info,
  37                                                  signal_name);
  38     else if (GI_IS_INTERFACE_INFO (info))
  39         signal_info = g_interface_info_find_signal ((GIInterfaceInfo *) info,
  40                                                     signal_name);
  41
  42     g_base_info_unref (info);
  43     return signal_info;
  44 }
  45
  46 static void
  47 pygi_signal_closure_invalidate(gpointer data,
  48                                GClosure *closure)
  49 {
  50     PyGClosure *pc = (PyGClosure *)closure;
  51     PyGILState_STATE state;
  52
  53     state = PyGILState_Ensure();
  54     Py_XDECREF(pc->callback);
  55     Py_XDECREF(pc->extra_args);
  56     Py_XDECREF(pc->swap_data);
  57     PyGILState_Release(state);
  58
  59     pc->callback = NULL;
  60     pc->extra_args = NULL;
  61     pc->swap_data = NULL;
  62
  63     g_base_info_unref (((PyGISignalClosure *) pc)->signal_info);
  64     ((PyGISignalClosure *) pc)->signal_info = NULL;
  65 }
  66
  67 static void
  68 pygi_signal_closure_marshal(GClosure *closure,
  69                             GValue *return_value,
  70                             guint n_param_values,
  71                             const GValue *param_values,
  72                             gpointer invocation_hint,
  73                             gpointer marshal_data)
  74 {
  75     PyGILState_STATE state;
  76     PyGClosure *pc = (PyGClosure *)closure;
  77     PyObject *params, *ret = NULL;
  78     guint i;
  79     GISignalInfo *signal_info;
  80     gint n_sig_info_args;
  81     gint sig_info_highest_arg;
  82     GSList *list_item = NULL;
  83     GSList *pass_by_ref_structs = NULL;
  84
  85     state = PyGILState_Ensure();
  86
  87     signal_info = ((PyGISignalClosure *)closure)->signal_info;
  88     n_sig_info_args = g_callable_info_get_n_args(signal_info);
  89     /* the first argument to a signal callback is instance,
  90        but instance is not counted in the introspection data */
  91     sig_info_highest_arg = n_sig_info_args + 1;
  92     g_assert_cmpint(sig_info_highest_arg, ==, n_param_values);
  93
  94     /* construct Python tuple for the parameter values */
  95     params = PyTuple_New(n_param_values);
  96     for (i = 0; i < n_param_values; i++) {
  97         /* swap in a different initial data for connect_object() */
  98         if (i == 0 && G_CCLOSURE_SWAP_DATA(closure)) {
  99             g_return_if_fail(pc->swap_data != NULL);
 100             Py_INCREF(pc->swap_data);
 101             PyTuple_SetItem(params, 0, pc->swap_data);
 102
 103         } else if (i == 0) {
 104             PyObject *item = pyg_value_as_pyobject(&param_values[i], FALSE);
 105
 106             if (!item) {
 107                 goto out;
 108             }
 109             PyTuple_SetItem(params, i, item);
 110
 111         } else if (i < sig_info_highest_arg) {
 112             GIArgInfo arg_info;
 113             GITypeInfo type_info;
 114             GITypeTag type_tag;
 115             GIArgument arg = { 0, };
 116             PyObject *item = NULL;
 117             gboolean free_array = FALSE;
 118             gboolean pass_struct_by_ref = FALSE;
 119
 120             g_callable_info_load_arg(signal_info, i - 1, &arg_info);
 121             g_arg_info_load_type(&arg_info, &type_info);
 122
 123             arg = _pygi_argument_from_g_value(&param_values[i], &type_info);
 124
 125             type_tag = g_type_info_get_tag (&type_info);
 126             if (type_tag == GI_TYPE_TAG_ARRAY) {
 127                 /* Skip the self argument of param_values */
 128                 arg.v_pointer = _pygi_argument_to_array (&arg,
 129                                                          _pygi_argument_array_length_marshal,
 130                                                          (void *)(param_values + 1),
 131                                                          signal_info,
 132                                                          &type_info,
 133                                                          &free_array);
 134             }
 135
 136             /* Hack to ensure struct arguments are passed-by-reference allowing
 137              * callback implementors to modify the struct values. This is needed
 138              * for keeping backwards compatibility and should be removed in future
 139              * versions which support signal output arguments as return values.
 140              * See: https://bugzilla.gnome.org/show_bug.cgi?id=735486
 141              *
 142              * Note the logic here must match the logic path taken in _pygi_argument_to_object.
 143              */
 144             if (type_tag == GI_TYPE_TAG_INTERFACE) {
 145                 GIBaseInfo *info = g_type_info_get_interface (&type_info);
 146                 GIInfoType info_type = g_base_info_get_type (info);
 147
 148                 if (info_type == GI_INFO_TYPE_STRUCT ||
 149                         info_type == GI_INFO_TYPE_BOXED ||
 150                         info_type == GI_INFO_TYPE_UNION) {
 151
 152                     GType gtype = g_registered_type_info_get_g_type ((GIRegisteredTypeInfo *) info);
 153                     gboolean is_foreign = (info_type == GI_INFO_TYPE_STRUCT) &&
 154                                           (g_struct_info_is_foreign ((GIStructInfo *) info));
 155
 156                     if (!is_foreign && !g_type_is_a (gtype, G_TYPE_VALUE) &&
 157                             g_type_is_a (gtype, G_TYPE_BOXED)) {
 158                         pass_struct_by_ref = TRUE;
 159                     }
 160                 }
 161
 162                 g_base_info_unref (info);
 163             }
 164
 165             if (pass_struct_by_ref) {
 166                 /* transfer everything will ensure the struct is not copied when wrapped. */
 167                 item = _pygi_argument_to_object (&arg, &type_info, GI_TRANSFER_EVERYTHING);
 168                 if (item && PyObject_IsInstance (item, (PyObject *) &PyGIBoxed_Type)) {
 169                     ((PyGBoxed *)item)->free_on_dealloc = FALSE;
 170                     pass_by_ref_structs = g_slist_prepend (pass_by_ref_structs, item);
 171                 }
 172
 173             } else {
 174                 item = _pygi_argument_to_object (&arg, &type_info, GI_TRANSFER_NOTHING);
 175             }
 176
 177             if (free_array) {
 178                 g_array_free (arg.v_pointer, FALSE);
 179             }
 180
 181             if (item == NULL) {
 182                 goto out;
 183             }
 184             PyTuple_SetItem(params, i, item);
 185         }
 186     }
 187     /* params passed to function may have extra arguments */
 188     if (pc->extra_args) {
 189         PyObject *tuple = params;
 190         params = PySequence_Concat(tuple, pc->extra_args);
 191         Py_DECREF(tuple);
 192     }
 193     ret = PyObject_CallObject(pc->callback, params);
 194     if (ret == NULL) {
 195         if (pc->exception_handler)
 196             pc->exception_handler(return_value, n_param_values, param_values);
 197         else
 198             PyErr_Print();
 199         goto out;
 200     }
 201
 202     if (G_IS_VALUE(return_value) && pyg_value_from_pyobject(return_value, ret) != 0) {
 203         PyErr_SetString(PyExc_TypeError,
 204                         "can't convert return value to desired type");
 205
 206         if (pc->exception_handler)
 207             pc->exception_handler(return_value, n_param_values, param_values);
 208         else
 209             PyErr_Print();
 210     }
 211     Py_DECREF(ret);
 212
 213     /* Run through the list of structs which have been passed by reference and
 214      * check if they are being held longer than the duration of the callback
 215      * execution. This is determined if the ref count is greater than 1.
 216      * A single ref is held by the argument list and any more would mean the callback
 217      * stored a ref somewhere else. In this case we make an internal copy of
 218      * the boxed struct so Python can own the memory to it.
 219      */
 220     list_item = pass_by_ref_structs;
 221     while (list_item) {
 222         PyObject *item = list_item->data;
 223         if (item->ob_refcnt > 1) {
 224             _pygi_boxed_copy_in_place ((PyGIBoxed *)item);
 225         }
 226         list_item = g_slist_next (list_item);
 227     }
 228
 229  out:
 230     g_slist_free (pass_by_ref_structs);
 231     Py_DECREF(params);
 232     PyGILState_Release(state);
 233 }
 234
 235 GClosure *
 236 pygi_signal_closure_new (PyGObject *instance,
 237                          GType g_type,
 238                          const gchar *signal_name,
 239                          PyObject *callback,
 240                          PyObject *extra_args,
 241                          PyObject *swap_data)
 242 {
 243     GClosure *closure = NULL;
 244     PyGISignalClosure *pygi_closure = NULL;
 245     GISignalInfo *signal_info = NULL;
 246
 247     g_return_val_if_fail(callback != NULL, NULL);
 248
 249     signal_info = _pygi_lookup_signal_from_g_type (g_type, signal_name);
 250     if (signal_info == NULL)
 251         return NULL;
 252
 253     closure = g_closure_new_simple(sizeof(PyGISignalClosure), NULL);
 254     g_closure_add_invalidate_notifier(closure, NULL, pygi_signal_closure_invalidate);
 255     g_closure_set_marshal(closure, pygi_signal_closure_marshal);
 256
 257     pygi_closure = (PyGISignalClosure *)closure;
 258
 259     pygi_closure->signal_info = signal_info;
 260     Py_INCREF(callback);
 261     pygi_closure->pyg_closure.callback = callback;
 262
 263     if (extra_args != NULL && extra_args != Py_None) {
 264         Py_INCREF(extra_args);
 265         if (!PyTuple_Check(extra_args)) {
 266             PyObject *tmp = PyTuple_New(1);
 267             PyTuple_SetItem(tmp, 0, extra_args);
 268             extra_args = tmp;
 269         }
 270         pygi_closure->pyg_closure.extra_args = extra_args;
 271     }
 272     if (swap_data) {
 273         Py_INCREF(swap_data);
 274         pygi_closure->pyg_closure.swap_data = swap_data;
 275         closure->derivative_flag = TRUE;
 276     }
 277
 278     return closure;
 279 }