dbus.c

   1 /* -*- Mode: C ; c-basic-offset: 2 -*- */
   2 /*
   3  * ALSA SEQ < - > JACK MIDI bridge
   4  *
   5  * Copyright (c) 2007,2008 Nedko Arnaudov <nedko@arnaudov.name>
   6  * Copyright (C) 2007-2008 Juuso Alasuutari
   7  *
   8  *  This program is free software; you can redistribute it and/or modify
   9  *  it under the terms of the GNU General Public License as published by
  10  *  the Free Software Foundation; version 2 of the License.
  11  *
  12  *  This program is distributed in the hope that it will be useful,
  13  *  but WITHOUT ANY WARRANTY; without even the implied warranty of
  14  *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  15  *  GNU General Public License for more details.
  16  *
  17  *  You should have received a copy of the GNU General Public License
  18  *  along with this program; if not, write to the Free Software
  19  *  Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA  02111-1307 USA
  20  */
  21
  22 #include <stdbool.h>
  23 #include <stdio.h>
  24 #include <string.h>
  25 #include <dbus/dbus.h>
  26
  27 #include "dbus.h"
  28 #include "log.h"
  29 #include "dbus_internal.h"
  30 #include "dbus_iface_control.h"
  31
  32 void
  33 a2j_dbus_error(
  34   void *dbus_call_context_ptr,
  35   const char *error_name,
  36   const char *format,
  37   ...)
  38 {
  39   va_list ap;
  40   char buffer[300];
  41
  42   va_start(ap, format);
  43
  44   vsnprintf(buffer, sizeof(buffer), format, ap);
  45
  46   a2j_error("%s", buffer);
  47   if (dbus_call_context_ptr != NULL)
  48   {
  49     ((struct a2j_dbus_method_call *)dbus_call_context_ptr)->reply = dbus_message_new_error(
  50       ((struct a2j_dbus_method_call *)dbus_call_context_ptr)->message,
  51       error_name,
  52       buffer);
  53   }
  54
  55   va_end(ap);
  56 }
  57
  58 /*
  59  * Send a method return.
  60  *
  61  * If call->reply is NULL (i.e. a message construct method failed
  62  * due to lack of memory) attempt to send a void method return.
  63  */
  64 static
  65 void
  66 a2j_dbus_send_method_return(
  67   struct a2j_dbus_method_call * call)
  68 {
  69   if (call->reply == NULL)
  70   {
  71     a2j_debug("send_method_return() called with a NULL message, trying to construct a void return...");
  72
  73     call->reply = dbus_message_new_method_return(call->message);
  74     if (call->reply == NULL)
  75     {
  76       a2j_error("Failed to construct method return!");
  77       return;
  78     }
  79   }
  80
  81   if (!dbus_connection_send(call->connection, call->reply, NULL))
  82   {
  83     a2j_error("Ran out of memory trying to queue method return");
  84   }
  85
  86   dbus_connection_flush(call->connection);
  87   dbus_message_unref(call->reply);
  88   call->reply = NULL;
  89 }
  90
  91 /*
  92  * Construct a method return which holds a single argument or, if
  93  * the type parameter is DBUS_TYPE_INVALID, no arguments at all
  94  * (a void message).
  95  *
  96  * The operation can only fail due to lack of memory, in which case
  97  * there's no sense in trying to construct an error return. Instead,
  98  * call->reply will be set to NULL and handled in send_method_return().
  99  */
 100 void
 101 a2j_dbus_construct_method_return_single(
 102     struct a2j_dbus_method_call * call_ptr,
 103     int type,
 104     void * arg)
 105 {
 106     DBusMessageIter iter;
 107
 108     call_ptr->reply = dbus_message_new_method_return(call_ptr->message);
 109     if (call_ptr->reply == NULL)
 110     {
 111         goto fail_no_mem;
 112     }
 113
 114     dbus_message_iter_init_append(call_ptr->reply, &iter);
 115
 116     if (!dbus_message_iter_append_basic(&iter, type, arg))
 117     {
 118         dbus_message_unref(call_ptr->reply);
 119         call_ptr->reply = NULL;
 120         goto fail_no_mem;
 121     }
 122
 123     return;
 124
 125 fail_no_mem:
 126     a2j_error("Ran out of memory trying to construct method return");
 127 }
 128
 129 #define descriptor_ptr ((struct a2j_dbus_object_descriptor *)data)
 130
 131 DBusHandlerResult
 132 a2j_dbus_message_handler(
 133   DBusConnection * connection,
 134   DBusMessage * message,
 135   void * data)
 136 {
 137   struct a2j_dbus_method_call call;
 138   const char *interface_name;
 139   struct a2j_dbus_interface_descriptor ** interface_ptr_ptr;
 140
 141   /* Check if the message is a method call. If not, ignore it. */
 142   if (dbus_message_get_type (message) != DBUS_MESSAGE_TYPE_METHOD_CALL)
 143   {
 144     goto handled;
 145   }
 146
 147   /* Get the invoked method's name and make sure it's non-NULL. */
 148   if (!(call.method_name = dbus_message_get_member (message)))
 149   {
 150     a2j_dbus_error(
 151       &call,
 152       A2J_DBUS_ERROR_UNKNOWN_METHOD,
 153       "Received method call with empty method name");
 154     goto send_return;
 155   }
 156
 157   /* Initialize our data. */
 158   call.context = descriptor_ptr->context;
 159   call.connection = connection;
 160   call.message = message;
 161   call.reply = NULL;
 162
 163   /* Check if there's an interface specified for this method call. */
 164   interface_name = dbus_message_get_interface (message);
 165   if (interface_name != NULL)
 166   {
 167     /* Check if we can match the interface and method.
 168      * The inteface handler functions only return false if the
 169      * method name was unknown, otherwise they run the specified
 170      * method and return TRUE.
 171      */
 172
 173     interface_ptr_ptr = descriptor_ptr->interfaces;
 174
 175     while (*interface_ptr_ptr != NULL)
 176     {
 177       if (strcmp(interface_name, (*interface_ptr_ptr)->name) == 0)
 178       {
 179         if (!(*interface_ptr_ptr)->handler(&call, (*interface_ptr_ptr)->methods))
 180         {
 181           break;
 182         }
 183
 184         goto send_return;
 185       }
 186
 187       interface_ptr_ptr++;
 188     }
 189   }
 190   else
 191   {
 192     /* No interface was specified so we have to try them all. This is
 193      * dictated by the D-Bus specification which states that method calls
 194      * omitting the interface must never be rejected.
 195      */
 196
 197     interface_ptr_ptr = descriptor_ptr->interfaces;
 198
 199     while (*interface_ptr_ptr != NULL)
 200     {
 201       if ((*interface_ptr_ptr)->handler(&call, (*interface_ptr_ptr)->methods))
 202       {
 203         goto send_return;
 204       }
 205
 206       interface_ptr_ptr++;
 207     }
 208   }
 209
 210   a2j_dbus_error(
 211     &call,
 212     A2J_DBUS_ERROR_UNKNOWN_METHOD,
 213     "Method \"%s\" with signature \"%s\" on interface \"%s\" doesn't exist",
 214     call.method_name,
 215     dbus_message_get_signature(message),
 216     interface_name);
 217
 218 send_return:
 219   a2j_dbus_send_method_return(&call);
 220
 221 handled:
 222   return DBUS_HANDLER_RESULT_HANDLED;
 223 }
 224
 225 void
 226 a2j_dbus_message_handler_unregister(
 227     DBusConnection *connection,
 228     void *data)
 229 {
 230     a2j_debug("Message handler was unregistered");
 231 }
 232
 233 #undef descriptor_ptr
 234
 235 /*
 236  * Check if the supplied method name exists in method descriptor,
 237  * if it does execute it and return TRUE. Otherwise return FALSE.
 238  */
 239 bool
 240 a2j_dbus_run_method(
 241     struct a2j_dbus_method_call *call,
 242     const struct a2j_dbus_interface_method_descriptor * methods)
 243 {
 244     const struct a2j_dbus_interface_method_descriptor * method_ptr;
 245
 246     method_ptr = methods;
 247
 248     while (method_ptr->name != NULL)
 249     {
 250         if (strcmp(call->method_name, method_ptr->name) == 0)
 251         {
 252             method_ptr->handler(call);
 253             return TRUE;
 254         }
 255
 256         method_ptr++;
 257     }
 258
 259     return FALSE;
 260 }
 261
 262 static DBusConnection * g_dbus_connection_ptr;
 263 static struct a2j_dbus_object_descriptor g_a2j_dbus_object_descriptor;
 264 struct a2j_dbus_interface_descriptor * g_a2j_dbus_interfaces[] =
 265 {
 266     &g_a2j_iface_introspectable,
 267     &g_a2j_iface_control,
 268     NULL
 269 };
 270
 271 bool
 272 a2j_dbus_is_available()
 273 {
 274   return g_dbus_connection_ptr != NULL;
 275 }
 276
 277 bool
 278 a2j_dbus_init()
 279 {
 280         DBusError dbus_error;
 281   int ret;
 282     DBusObjectPathVTable vtable =
 283     {
 284         a2j_dbus_message_handler_unregister,
 285         a2j_dbus_message_handler,
 286         NULL
 287     };
 288
 289         dbus_error_init(&dbus_error);
 290   g_dbus_connection_ptr = dbus_bus_get(DBUS_BUS_SESSION, &dbus_error);
 291         if (dbus_error_is_set(&dbus_error))
 292   {
 293                 a2j_error("Failed to get bus: %s", dbus_error.message);
 294                 goto fail;
 295         }
 296
 297   dbus_connection_set_exit_on_disconnect(g_dbus_connection_ptr, FALSE);
 298
 299   a2j_debug("D-Bus unique name is '%s'", dbus_bus_get_unique_name(g_dbus_connection_ptr));
 300
 301   ret = dbus_bus_request_name(g_dbus_connection_ptr, A2J_DBUS_SERVICE_NAME, DBUS_NAME_FLAG_DO_NOT_QUEUE, &dbus_error);
 302   if (ret == -1)
 303   {
 304     a2j_error("Failed to acquire bus name: %s", dbus_error.message);
 305     goto fail_unref_dbus_connection;
 306   }
 307
 308   if (ret == DBUS_REQUEST_NAME_REPLY_EXISTS)
 309   {
 310     a2j_error("Requested bus name already exists");
 311     goto fail_unref_dbus_connection;
 312   }
 313
 314   g_a2j_dbus_object_descriptor.context = NULL;
 315   g_a2j_dbus_object_descriptor.interfaces = g_a2j_dbus_interfaces;
 316
 317   if (!dbus_connection_register_object_path(
 318         g_dbus_connection_ptr,
 319         A2J_DBUS_OBJECT_PATH,
 320         &vtable,
 321         &g_a2j_dbus_object_descriptor))
 322   {
 323     a2j_error("Ran out of memory trying to register D-Bus object path");
 324     goto fail_unref_dbus_connection;
 325   }
 326
 327   return true;
 328
 329 fail_unref_dbus_connection:
 330   dbus_connection_unref(g_dbus_connection_ptr);
 331   g_dbus_connection_ptr = NULL;
 332
 333 fail:
 334
 335   return false;
 336 }
 337
 338 bool
 339 a2j_dbus_run(
 340   int timeout_milliseconds)
 341 {
 342   return dbus_connection_read_write_dispatch(g_dbus_connection_ptr, timeout_milliseconds);
 343 }
 344
 345 void
 346 a2j_dbus_uninit()
 347 {
 348   dbus_connection_unref(g_dbus_connection_ptr);
 349   g_dbus_connection_ptr = NULL;
 350 }
 351
 352 void
 353 a2j_dbus_signal(
 354   const char * path,
 355   const char * interface,
 356   const char * name,
 357   int type,
 358   ...)
 359 {
 360   va_list ap;
 361         DBusMessage * message_ptr;
 362
 363   a2j_debug("Sending signal %s.%s from %s", interface, name, path);
 364
 365   if (!a2j_dbus_is_available())
 366   {
 367     a2j_error("Internal error: cannot send D-Bus signal without D-Bus being initialized");
 368     return;
 369   }
 370
 371   message_ptr = dbus_message_new_signal (path, interface, name);
 372
 373   if (message_ptr == NULL)
 374   {
 375     a2j_error("Ran out of memory trying to create new signal");
 376     return;
 377   }
 378
 379   va_start(ap, type);
 380   if (dbus_message_append_args_valist(message_ptr, type, ap))
 381   {
 382     if (!dbus_connection_send(g_dbus_connection_ptr, message_ptr, NULL))
 383     {
 384       a2j_error("Ran out of memory trying to queue signal");
 385     }
 386
 387     dbus_connection_flush(g_dbus_connection_ptr);
 388   }
 389   else
 390   {
 391     a2j_error("Ran out of memory trying to append signal argument(s)");
 392   }
 393   va_end(ap);
 394
 395   dbus_message_unref(message_ptr);
 396 }