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_ptr->reply will be set to NULL and handled in send_method_return().
  41  */
  42 void
  43 method_return_new_void(struct dbus_method_call * call_ptr)
  44 {
  45   if (!(call_ptr->reply = dbus_message_new_method_return(call_ptr->message))) {
  46     log_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_ptr->reply will be set to NULL and handled in send_method_return().
  58  */
  59 void
  60 method_return_new_single(struct dbus_method_call * call_ptr,
  61                          int            type,
  62                          const void    *arg)
  63 {
  64   if (!call_ptr || !arg) {
  65     log_error("Invalid arguments");
  66     return;
  67   }
  68
  69   call_ptr->reply = dbus_message_new_method_return(call_ptr->message);
  70
  71   if (!call_ptr->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_ptr->reply, &iter);
  86
  87   if (dbus_message_iter_append_basic(&iter, type, arg))
  88     return;
  89
  90   dbus_message_unref(call_ptr->reply);
  91   call_ptr->reply = NULL;
  92
  93 fail_no_mem:
  94   log_error("Ran out of memory trying to construct method return");
  95 }
  96
  97 void
  98 method_return_new_valist(struct dbus_method_call * call_ptr,
  99                          int            type,
 100                                         ...)
 101 {
 102   if (!call_ptr) {
 103     log_error("Call pointer is NULL");
 104     return;
 105   }
 106
 107   if (type == DBUS_TYPE_INVALID) {
 108     log_error("No argument(s) supplied");
 109     return;
 110   }
 111
 112   va_list argp;
 113
 114   call_ptr->reply = dbus_message_new_method_return(call_ptr->message);
 115   if (!call_ptr->reply)
 116     goto fail_no_mem;
 117
 118   va_start(argp, type);
 119
 120   if (dbus_message_append_args_valist(call_ptr->reply, type, argp)) {
 121     va_end(argp);
 122     return;
 123   }
 124
 125   va_end(argp);
 126
 127   dbus_message_unref(call_ptr->reply);
 128   call_ptr->reply = NULL;
 129
 130 fail_no_mem:
 131   log_error("Ran out of memory trying to construct method return");
 132 }
 133
 134 /*
 135  * Send a method return.
 136  *
 137  * If call_ptr->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(struct dbus_method_call * call_ptr)
 142 {
 143   if (call_ptr->reply) {
 144   retry_send:
 145     if (!dbus_connection_send(call_ptr->connection, call_ptr->reply, NULL))
 146       log_error("Ran out of memory trying to queue "
 147                  "method return");
 148     else
 149       dbus_connection_flush(call_ptr->connection);
 150
 151     dbus_message_unref(call_ptr->reply);
 152     call_ptr->reply = NULL;
 153   } else {
 154     log_debug("Message was NULL, trying to construct a void return");
 155
 156     if ((call_ptr->reply = dbus_message_new_method_return(call_ptr->message))) {
 157       log_debug("Constructed a void return, trying to queue it");
 158       goto retry_send;
 159     } else {
 160       log_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     log_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 }