dbus/method.c

   1 /* -*- Mode: C ; c-basic-offset: 2 -*- */
   2 /*
   3  * LADI Session Handler (ladish)
   4  *
   5  * Copyright (C) 2008, 2009, 2010 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 "helpers.h"
  32 #include "method.h"
  33
  34 /*
  35  * Construct a void method return.
  36  *
  37  * The operation can only fail due to lack of memory, in which case
  38  * there's no sense in trying to construct an error return. Instead,
  39  * call_ptr->reply will be set to NULL and handled in send_method_return().
  40  */
  41 void
  42 method_return_new_void(struct dbus_method_call * call_ptr)
  43 {
  44   if (!(call_ptr->reply = dbus_message_new_method_return(call_ptr->message))) {
  45     log_error("Ran out of memory trying to construct method return");
  46   }
  47 }
  48
  49 /*
  50  * Construct a method return which holds a single argument or, if
  51  * the type parameter is DBUS_TYPE_INVALID, no arguments at all
  52  * (a void message).
  53  *
  54  * The operation can only fail due to lack of memory, in which case
  55  * there's no sense in trying to construct an error return. Instead,
  56  * call_ptr->reply will be set to NULL and handled in send_method_return().
  57  */
  58 void
  59 method_return_new_single(struct dbus_method_call * call_ptr,
  60                          int            type,
  61                          const void    *arg)
  62 {
  63   if (!call_ptr || !arg) {
  64     log_error("Invalid arguments");
  65     return;
  66   }
  67
  68   call_ptr->reply = dbus_message_new_method_return(call_ptr->message);
  69
  70   if (!call_ptr->reply)
  71     goto fail_no_mem;
  72
  73   /* Prevent crash on NULL input string. */
  74   if (type == DBUS_TYPE_STRING && !(*((const char **) arg)))
  75     *((const char **) arg) = "";
  76
  77   DBusMessageIter iter;
  78
  79   dbus_message_iter_init_append(call_ptr->reply, &iter);
  80
  81   if (dbus_message_iter_append_basic(&iter, type, arg))
  82     return;
  83
  84   dbus_message_unref(call_ptr->reply);
  85   call_ptr->reply = NULL;
  86
  87 fail_no_mem:
  88   log_error("Ran out of memory trying to construct method return");
  89 }
  90
  91 void
  92 method_return_new_valist(struct dbus_method_call * call_ptr,
  93                          int            type,
  94                                         ...)
  95 {
  96   if (!call_ptr) {
  97     log_error("Call pointer is NULL");
  98     return;
  99   }
 100
 101   if (type == DBUS_TYPE_INVALID) {
 102     log_error("No argument(s) supplied");
 103     return;
 104   }
 105
 106   va_list argp;
 107
 108   call_ptr->reply = dbus_message_new_method_return(call_ptr->message);
 109   if (!call_ptr->reply)
 110     goto fail_no_mem;
 111
 112   va_start(argp, type);
 113
 114   if (dbus_message_append_args_valist(call_ptr->reply, type, argp)) {
 115     va_end(argp);
 116     return;
 117   }
 118
 119   va_end(argp);
 120
 121   dbus_message_unref(call_ptr->reply);
 122   call_ptr->reply = NULL;
 123
 124 fail_no_mem:
 125   log_error("Ran out of memory trying to construct method return");
 126 }
 127
 128 /*
 129  * Send a method return.
 130  *
 131  * If call_ptr->reply is NULL, i.e. a previous attempt to construct
 132  * a return has failed, attempt to send a void return.
 133  */
 134 void
 135 method_return_send(struct dbus_method_call * call_ptr)
 136 {
 137   if (call_ptr->reply) {
 138   retry_send:
 139     if (!dbus_connection_send(call_ptr->connection, call_ptr->reply, NULL))
 140       log_error("Ran out of memory trying to queue "
 141                  "method return");
 142     else
 143       dbus_connection_flush(call_ptr->connection);
 144
 145     dbus_message_unref(call_ptr->reply);
 146     call_ptr->reply = NULL;
 147   } else {
 148     log_debug("Message was NULL, trying to construct a void return");
 149
 150     if ((call_ptr->reply = dbus_message_new_method_return(call_ptr->message))) {
 151       log_debug("Constructed a void return, trying to queue it");
 152       goto retry_send;
 153     } else {
 154       log_error("Failed to construct method return!");
 155     }
 156   }
 157 }
 158
 159 bool
 160 method_return_verify(DBusMessage  *msg,
 161                      const char  **str)
 162 {
 163   if (!msg || dbus_message_get_type(msg) != DBUS_MESSAGE_TYPE_ERROR)
 164     return true;
 165
 166   const char *ptr;
 167
 168   if (!dbus_message_get_args(msg, &g_dbus_error,
 169                              DBUS_TYPE_STRING, &ptr,
 170                              DBUS_TYPE_INVALID)) {
 171     log_error("Cannot read description from D-Bus error message: %s ",
 172                g_dbus_error.message);
 173     dbus_error_free(&g_dbus_error);
 174     ptr = NULL;
 175   }
 176
 177   if (str)
 178     *str = ptr;
 179
 180   return false;
 181 }