dbus/method.c

   1 /* -*- Mode: C ; c-basic-offset: 2 -*- */
   2 /*
   3  * LADI Session Handler (ladish)
   4  *
   5  * Copyright (C) 2008, 2009 Nedko Arnaudov <nedko@arnaudov.name>
   6  * Copyright (C) 2008 Juuso Alasuutari <juuso.alasuutari@gmail.com>
   7  *
   8  **************************************************************************
   9  * This file contains D-Bus methods helpers
  10  **************************************************************************
  11  *
  12  * Licensed under the Academic Free License version 2.1
  13  *
  14  * LADI Session Handler is free software; you can redistribute it and/or modify
  15  * it under the terms of the GNU General Public License as published by
  16  * the Free Software Foundation; either version 2 of the License, or
  17  * (at your option) any later version.
  18  *
  19  * LADI Session Handler is distributed in the hope that it will be useful,
  20  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  21  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  22  * GNU General Public License for more details.
  23  *
  24  * You should have received a copy of the GNU General Public License
  25  * along with LADI Session Handler. If not, see <http://www.gnu.org/licenses/>
  26  * or write to the Free Software Foundation, Inc.,
  27  * 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  28  */
  29
  30 #include "../common.h"
  31 #include "../common/safety.h"
  32 #include "helpers.h"
  33 #include "method.h"
  34
  35 /*
  36  * Construct a void method return.
  37  *
  38  * The operation can only fail due to lack of memory, in which case
  39  * there's no sense in trying to construct an error return. Instead,
  40  * call->reply will be set to NULL and handled in send_method_return().
  41  */
  42 void
  43 method_return_new_void(method_call_t *call)
  44 {
  45   if (!(call->reply = dbus_message_new_method_return(call->message))) {
  46     lash_error("Ran out of memory trying to construct method return");
  47   }
  48 }
  49
  50 /*
  51  * Construct a method return which holds a single argument or, if
  52  * the type parameter is DBUS_TYPE_INVALID, no arguments at all
  53  * (a void message).
  54  *
  55  * The operation can only fail due to lack of memory, in which case
  56  * there's no sense in trying to construct an error return. Instead,
  57  * call->reply will be set to NULL and handled in send_method_return().
  58  */
  59 void
  60 method_return_new_single(method_call_t *call,
  61                          int            type,
  62                          const void    *arg)
  63 {
  64   if (!call || !arg) {
  65     lash_error("Invalid arguments");
  66     return;
  67   }
  68
  69   call->reply = dbus_message_new_method_return(call->message);
  70
  71   if (!call->reply)
  72     goto fail_no_mem;
  73
  74   /* Void method return requested by caller. */
  75   // TODO: do we really need this?
  76   if (type == DBUS_TYPE_INVALID)
  77     return;
  78
  79   /* Prevent crash on NULL input string. */
  80   if (type == DBUS_TYPE_STRING && !(*((const char **) arg)))
  81     *((const char **) arg) = "";
  82
  83   DBusMessageIter iter;
  84
  85   dbus_message_iter_init_append(call->reply, &iter);
  86
  87   if (dbus_message_iter_append_basic(&iter, type, arg))
  88     return;
  89
  90   dbus_message_unref(call->reply);
  91   call->reply = NULL;
  92
  93 fail_no_mem:
  94   lash_error("Ran out of memory trying to construct method return");
  95 }
  96
  97 void
  98 method_return_new_valist(method_call_t *call,
  99                          int            type,
 100                                         ...)
 101 {
 102   if (!call) {
 103     lash_error("Call pointer is NULL");
 104     return;
 105   }
 106
 107   if (type == DBUS_TYPE_INVALID) {
 108     lash_error("No argument(s) supplied");
 109     return;
 110   }
 111
 112   va_list argp;
 113
 114   call->reply = dbus_message_new_method_return(call->message);
 115   if (!call->reply)
 116     goto fail_no_mem;
 117
 118   va_start(argp, type);
 119
 120   if (dbus_message_append_args_valist(call->reply, type, argp)) {
 121     va_end(argp);
 122     return;
 123   }
 124
 125   va_end(argp);
 126
 127   dbus_message_unref(call->reply);
 128   call->reply = NULL;
 129
 130 fail_no_mem:
 131   lash_error("Ran out of memory trying to construct method return");
 132 }
 133
 134 /*
 135  * Send a method return.
 136  *
 137  * If call->reply is NULL, i.e. a previous attempt to construct
 138  * a return has failed, attempt to send a void return.
 139  */
 140 void
 141 method_return_send(method_call_t *call)
 142 {
 143   if (call->reply) {
 144   retry_send:
 145     if (!dbus_connection_send(call->connection, call->reply, NULL))
 146       lash_error("Ran out of memory trying to queue "
 147                  "method return");
 148     else
 149       dbus_connection_flush(call->connection);
 150
 151     dbus_message_unref(call->reply);
 152     call->reply = NULL;
 153   } else {
 154     lash_debug("Message was NULL, trying to construct a void return");
 155
 156     if ((call->reply = dbus_message_new_method_return(call->message))) {
 157       lash_debug("Constructed a void return, trying to queue it");
 158       goto retry_send;
 159     } else {
 160       lash_error("Failed to construct method return!");
 161     }
 162   }
 163 }
 164
 165 bool
 166 method_return_verify(DBusMessage  *msg,
 167                      const char  **str)
 168 {
 169   if (!msg || dbus_message_get_type(msg) != DBUS_MESSAGE_TYPE_ERROR)
 170     return true;
 171
 172   const char *ptr;
 173
 174   if (!dbus_message_get_args(msg, &g_dbus_error,
 175                              DBUS_TYPE_STRING, &ptr,
 176                              DBUS_TYPE_INVALID)) {
 177     lash_error("Cannot read description from D-Bus error message: %s ",
 178                g_dbus_error.message);
 179     dbus_error_free(&g_dbus_error);
 180     ptr = NULL;
 181   }
 182
 183   if (str)
 184     *str = ptr;
 185
 186   return false;
 187 }
 188
 189 /*
 190  * Append a variant type to a D-Bus message.
 191  * Return false if something fails, true otherwise.
 192  */
 193 bool
 194 method_iter_append_variant(DBusMessageIter *iter,
 195                            int              type,
 196                            const void      *arg)
 197 {
 198   DBusMessageIter sub_iter;
 199   char s[2];
 200
 201   s[0] = (char) type;
 202   s[1] = '\0';
 203
 204   /* Open a variant container. */
 205   if (!dbus_message_iter_open_container(iter, DBUS_TYPE_VARIANT,
 206                                         (const char *) s, &sub_iter))
 207     return false;
 208
 209   /* Append the supplied value. */
 210   if (!dbus_message_iter_append_basic(&sub_iter, type, arg)) {
 211     dbus_message_iter_close_container(iter, &sub_iter);
 212     return false;
 213   }
 214
 215   /* Close the container. */
 216   if (!dbus_message_iter_close_container(iter, &sub_iter))
 217     return false;
 218
 219   return true;
 220 }
 221
 222 static __inline__ bool
 223 method_iter_append_variant_raw(DBusMessageIter *iter,
 224                                const void      *buf,
 225                                int              len)
 226 {
 227   DBusMessageIter variant_iter, array_iter;
 228
 229   /* Open a variant container. */
 230   if (!dbus_message_iter_open_container(iter, DBUS_TYPE_VARIANT,
 231                                         "ay", &variant_iter))
 232     return false;
 233
 234   /* Open an array container. */
 235   if (!dbus_message_iter_open_container(&variant_iter, DBUS_TYPE_ARRAY,
 236                                         "y", &array_iter))
 237     goto fail;
 238
 239   /* Append the supplied data. */
 240   if (!dbus_message_iter_append_fixed_array(&array_iter, DBUS_TYPE_BYTE, buf, len)) {
 241     dbus_message_iter_close_container(&variant_iter, &array_iter);
 242     goto fail;
 243   }
 244
 245   /* Close the containers. */
 246   if (!dbus_message_iter_close_container(&variant_iter, &array_iter))
 247     goto fail;
 248   else if (!dbus_message_iter_close_container(iter, &variant_iter))
 249     return false;
 250
 251   return true;
 252
 253 fail:
 254   dbus_message_iter_close_container(iter, &variant_iter);
 255   return false;
 256 }
 257
 258 bool
 259 method_iter_append_dict_entry(DBusMessageIter *iter,
 260                               int              type,
 261                               const char      *key,
 262                               const void      *value,
 263                               int              length)
 264 {
 265   DBusMessageIter dict_iter;
 266
 267   if (!dbus_message_iter_open_container(iter, DBUS_TYPE_DICT_ENTRY,
 268                                         NULL, &dict_iter))
 269     return false;
 270
 271   if (!dbus_message_iter_append_basic(&dict_iter, DBUS_TYPE_STRING, &key))
 272     goto fail;
 273
 274   if (type == '-') {
 275     if (!method_iter_append_variant_raw(&dict_iter, value, length))
 276       goto fail;
 277   } else if (!method_iter_append_variant(&dict_iter, type, value))
 278     goto fail;
 279
 280   if (!dbus_message_iter_close_container(iter, &dict_iter))
 281     return false;
 282
 283   return true;
 284
 285 fail:
 286   dbus_message_iter_close_container(iter, &dict_iter);
 287   return false;
 288 }
 289
 290 bool
 291 method_iter_get_dict_entry(DBusMessageIter  *iter,
 292                            const char      **key_ptr,
 293                            void             *value_ptr,
 294                            int              *type_ptr,
 295                            int              *size_ptr)
 296 {
 297   if (!iter || !key_ptr || !value_ptr || !type_ptr) {
 298     lash_error("Invalid arguments");
 299     return false;
 300   }
 301
 302   DBusMessageIter dict_iter, variant_iter;
 303
 304   if (dbus_message_iter_get_arg_type(iter) != DBUS_TYPE_DICT_ENTRY) {
 305     lash_error("Iterator does not point to a dict entry container");
 306     return false;
 307   }
 308
 309   dbus_message_iter_recurse(iter, &dict_iter);
 310
 311   if (dbus_message_iter_get_arg_type(&dict_iter) != DBUS_TYPE_STRING) {
 312     lash_error("Cannot find key in dict entry container");
 313     return false;
 314   }
 315
 316   dbus_message_iter_get_basic(&dict_iter, key_ptr);
 317
 318   if (!dbus_message_iter_next(&dict_iter)
 319       || dbus_message_iter_get_arg_type(&dict_iter) != DBUS_TYPE_VARIANT) {
 320     lash_error("Cannot find variant container in dict entry");
 321     return false;
 322   }
 323
 324   dbus_message_iter_recurse(&dict_iter, &variant_iter);
 325
 326   *type_ptr = dbus_message_iter_get_arg_type(&variant_iter);
 327   if (*type_ptr == DBUS_TYPE_INVALID) {
 328     lash_error("Cannot find value in variant container");
 329     return false;
 330   }
 331
 332   if (*type_ptr == DBUS_TYPE_ARRAY) {
 333     DBusMessageIter array_iter;
 334     int n;
 335
 336     if (dbus_message_iter_get_element_type(&variant_iter)
 337         != DBUS_TYPE_BYTE) {
 338       lash_error("Dict entry value is a non-byte array");
 339       return false;
 340     }
 341     *type_ptr = '-';
 342
 343     dbus_message_iter_recurse(&variant_iter, &array_iter);
 344     dbus_message_iter_get_fixed_array(&array_iter, value_ptr, &n);
 345
 346     if (size_ptr)
 347       *size_ptr = n;
 348   } else
 349     dbus_message_iter_get_basic(&variant_iter, value_ptr);
 350
 351   return true;
 352 }
 353
 354 /* EOF */