gio/gunixfdmessage.c

   1 /* GIO - GLib Input, Output and Streaming Library
   2  *
   3  * Copyright © 2009 Codethink Limited
   4  *
   5  * This program is free software: you can redistribute it and/or modify
   6  * it under the terms of the GNU Lesser General Public License as published
   7  * by the Free Software Foundation; either version 2 of the licence or (at
   8  * your option) any later version.
   9  *
  10  * See the included COPYING file for more information.
  11  *
  12  * Authors: Ryan Lortie <desrt@desrt.ca>
  13  */
  14
  15 /**
  16  * SECTION:gunixfdmessage
  17  * @title: GUnixFDMessage
  18  * @short_description: A GSocketControlMessage containing a GUnixFDList
  19  * @include: gio/gunixfdmessage.h
  20  * @see_also: #GUnixConnection, #GUnixFDList, #GSocketControlMessage
  21  *
  22  * This #GSocketControlMessage contains a #GUnixFDList.
  23  * It may be sent using g_socket_send_message() and received using
  24  * g_socket_receive_message() over UNIX sockets (ie: sockets in the
  25  * %G_SOCKET_ADDRESS_UNIX family). The file descriptors are copied
  26  * between processes by the kernel.
  27  *
  28  * For an easier way to send and receive file descriptors over
  29  * stream-oriented UNIX sockets, see g_unix_connection_send_fd() and
  30  * g_unix_connection_receive_fd().
  31  *
  32  * Note that <filename>&lt;gio/gunixfdmessage.h&gt;</filename> belongs to
  33  * the UNIX-specific GIO interfaces, thus you have to use the
  34  * <filename>gio-unix-2.0.pc</filename> pkg-config file when using it.
  35  **/
  36
  37 #include "config.h"
  38
  39 #include <sys/types.h>
  40 #include <sys/socket.h>
  41 #include <unistd.h>
  42 #include <string.h>
  43 #include <fcntl.h>
  44 #include <errno.h>
  45
  46 #include "gunixfdmessage.h"
  47 #include "gunixfdlist.h"
  48 #include "gioerror.h"
  49
  50
  51
  52 G_DEFINE_TYPE (GUnixFDMessage, g_unix_fd_message,
  53                G_TYPE_SOCKET_CONTROL_MESSAGE);
  54
  55 struct _GUnixFDMessagePrivate
  56 {
  57   GUnixFDList *list;
  58 };
  59
  60 static gsize
  61 g_unix_fd_message_get_size (GSocketControlMessage *message)
  62 {
  63   GUnixFDMessage *fd_message = G_UNIX_FD_MESSAGE (message);
  64
  65   return g_unix_fd_list_get_length (fd_message->priv->list) * sizeof (gint);
  66 }
  67
  68 static int
  69 g_unix_fd_message_get_level (GSocketControlMessage *message)
  70 {
  71   return SOL_SOCKET;
  72 }
  73
  74 static int
  75 g_unix_fd_message_get_msg_type (GSocketControlMessage *message)
  76 {
  77   return SCM_RIGHTS;
  78 }
  79
  80 static GSocketControlMessage *
  81 g_unix_fd_message_deserialize (int      level,
  82                                int      type,
  83                                gsize    size,
  84                                gpointer data)
  85 {
  86   GSocketControlMessage *message;
  87   GUnixFDList *list;
  88   gint n, s, i;
  89   gint *fds;
  90
  91   if (level != SOL_SOCKET ||
  92       type != SCM_RIGHTS)
  93     return NULL;
  94
  95   if (size % 4 > 0)
  96     {
  97       g_warning ("Kernel returned non-integral number of fds");
  98       return NULL;
  99     }
 100
 101   fds = data;
 102   n = size / sizeof (gint);
 103
 104   /* Note we probably handled this in gsocket.c already if we're on
 105    * Linux and have MSG_CMSG_CLOEXEC, but this code remains as a fallback
 106    * in case the kernel is too old for MSG_CMSG_CLOEXEC.
 107    */
 108   for (i = 0; i < n; i++)
 109     {
 110       do
 111         s = fcntl (fds[i], F_SETFD, FD_CLOEXEC);
 112       while (s < 0 && errno == EINTR);
 113
 114       if (s < 0)
 115         {
 116           g_warning ("Error setting close-on-exec flag on incoming fd: %s",
 117                      g_strerror (errno));
 118           return NULL;
 119         }
 120     }
 121
 122   list = g_unix_fd_list_new_from_array (fds, n);
 123   message = g_unix_fd_message_new_with_fd_list (list);
 124   g_object_unref (list);
 125
 126   return message;
 127 }
 128
 129 static void
 130 g_unix_fd_message_serialize (GSocketControlMessage *message,
 131                              gpointer               data)
 132 {
 133   GUnixFDMessage *fd_message = G_UNIX_FD_MESSAGE (message);
 134   const gint *fds;
 135   gint n_fds;
 136
 137   fds = g_unix_fd_list_peek_fds (fd_message->priv->list, &n_fds);
 138   memcpy (data, fds, sizeof (gint) * n_fds);
 139 }
 140
 141 static void
 142 g_unix_fd_message_set_property (GObject *object, guint prop_id,
 143                                 const GValue *value, GParamSpec *pspec)
 144 {
 145   GUnixFDMessage *message = G_UNIX_FD_MESSAGE (object);
 146
 147   g_assert (message->priv->list == NULL);
 148   g_assert_cmpint (prop_id, ==, 1);
 149
 150   message->priv->list = g_value_dup_object (value);
 151
 152   if (message->priv->list == NULL)
 153     message->priv->list = g_unix_fd_list_new ();
 154 }
 155
 156 /**
 157  * g_unix_fd_message_get_fd_list:
 158  * @message: a #GUnixFDMessage
 159  *
 160  * Gets the #GUnixFDList contained in @message.  This function does not
 161  * return a reference to the caller, but the returned list is valid for
 162  * the lifetime of @message.
 163  *
 164  * Returns: (transfer none): the #GUnixFDList from @message
 165  *
 166  * Since: 2.24
 167  **/
 168 GUnixFDList *
 169 g_unix_fd_message_get_fd_list (GUnixFDMessage *message)
 170 {
 171   return message->priv->list;
 172 }
 173
 174 static void
 175 g_unix_fd_message_get_property (GObject *object, guint prop_id,
 176                                 GValue *value, GParamSpec *pspec)
 177 {
 178   GUnixFDMessage *message = G_UNIX_FD_MESSAGE (object);
 179
 180   g_assert_cmpint (prop_id, ==, 1);
 181
 182   g_value_set_object (value, g_unix_fd_message_get_fd_list (message));
 183 }
 184
 185 static void
 186 g_unix_fd_message_init (GUnixFDMessage *message)
 187 {
 188   message->priv = G_TYPE_INSTANCE_GET_PRIVATE (message,
 189                                                G_TYPE_UNIX_FD_MESSAGE,
 190                                                GUnixFDMessagePrivate);
 191 }
 192
 193 static void
 194 g_unix_fd_message_finalize (GObject *object)
 195 {
 196   GUnixFDMessage *message = G_UNIX_FD_MESSAGE (object);
 197
 198   g_object_unref (message->priv->list);
 199
 200   G_OBJECT_CLASS (g_unix_fd_message_parent_class)
 201     ->finalize (object);
 202 }
 203
 204 static void
 205 g_unix_fd_message_class_init (GUnixFDMessageClass *class)
 206 {
 207   GSocketControlMessageClass *scm_class = G_SOCKET_CONTROL_MESSAGE_CLASS (class);
 208   GObjectClass *object_class = G_OBJECT_CLASS (class);
 209
 210   g_type_class_add_private (class, sizeof (GUnixFDMessagePrivate));
 211   scm_class->get_size = g_unix_fd_message_get_size;
 212   scm_class->get_level = g_unix_fd_message_get_level;
 213   scm_class->get_type = g_unix_fd_message_get_msg_type;
 214   scm_class->serialize = g_unix_fd_message_serialize;
 215   scm_class->deserialize = g_unix_fd_message_deserialize;
 216   object_class->finalize = g_unix_fd_message_finalize;
 217   object_class->set_property = g_unix_fd_message_set_property;
 218   object_class->get_property = g_unix_fd_message_get_property;
 219
 220   g_object_class_install_property (object_class, 1,
 221     g_param_spec_object ("fd-list", "file descriptor list",
 222                          "The GUnixFDList object to send with the message",
 223                          G_TYPE_UNIX_FD_LIST, G_PARAM_STATIC_STRINGS |
 224                          G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY));
 225 }
 226
 227 /**
 228  * g_unix_fd_message_new:
 229  *
 230  * Creates a new #GUnixFDMessage containing an empty file descriptor
 231  * list.
 232  *
 233  * Returns: a new #GUnixFDMessage
 234  *
 235  * Since: 2.22
 236  **/
 237 GSocketControlMessage *
 238 g_unix_fd_message_new (void)
 239 {
 240   return g_object_new (G_TYPE_UNIX_FD_MESSAGE, NULL);
 241 }
 242
 243 /**
 244  * g_unix_fd_message_new_with_fd_list:
 245  * @fd_list: a #GUnixFDList
 246  *
 247  * Creates a new #GUnixFDMessage containing @list.
 248  *
 249  * Returns: a new #GUnixFDMessage
 250  *
 251  * Since: 2.24
 252  **/
 253 GSocketControlMessage *
 254 g_unix_fd_message_new_with_fd_list (GUnixFDList *fd_list)
 255 {
 256   return g_object_new (G_TYPE_UNIX_FD_MESSAGE,
 257                        "fd-list", fd_list,
 258                        NULL);
 259 }
 260
 261 /**
 262  * g_unix_fd_message_steal_fds:
 263  * @message: a #GUnixFDMessage
 264  * @length: (out) (allow-none): pointer to the length of the returned
 265  *     array, or %NULL
 266  *
 267  * Returns the array of file descriptors that is contained in this
 268  * object.
 269  *
 270  * After this call, the descriptors are no longer contained in
 271  * @message. Further calls will return an empty list (unless more
 272  * descriptors have been added).
 273  *
 274  * The return result of this function must be freed with g_free().
 275  * The caller is also responsible for closing all of the file
 276  * descriptors.
 277  *
 278  * If @length is non-%NULL then it is set to the number of file
 279  * descriptors in the returned array. The returned array is also
 280  * terminated with -1.
 281  *
 282  * This function never returns %NULL. In case there are no file
 283  * descriptors contained in @message, an empty array is returned.
 284  *
 285  * Returns: (array length=length) (transfer full): an array of file
 286  *     descriptors
 287  *
 288  * Since: 2.22
 289  **/
 290 gint *
 291 g_unix_fd_message_steal_fds (GUnixFDMessage *message,
 292                              gint           *length)
 293 {
 294   g_return_val_if_fail (G_UNIX_FD_MESSAGE (message), NULL);
 295
 296   return g_unix_fd_list_steal_fds (message->priv->list, length);
 297 }
 298
 299 /**
 300  * g_unix_fd_message_append_fd:
 301  * @message: a #GUnixFDMessage
 302  * @fd: a valid open file descriptor
 303  * @error: a #GError pointer
 304  *
 305  * Adds a file descriptor to @message.
 306  *
 307  * The file descriptor is duplicated using dup(). You keep your copy
 308  * of the descriptor and the copy contained in @message will be closed
 309  * when @message is finalized.
 310  *
 311  * A possible cause of failure is exceeding the per-process or
 312  * system-wide file descriptor limit.
 313  *
 314  * Returns: %TRUE in case of success, else %FALSE (and @error is set)
 315  *
 316  * Since: 2.22
 317  **/
 318 gboolean
 319 g_unix_fd_message_append_fd (GUnixFDMessage  *message,
 320                              gint             fd,
 321                              GError         **error)
 322 {
 323   g_return_val_if_fail (G_UNIX_FD_MESSAGE (message), FALSE);
 324
 325   return g_unix_fd_list_append (message->priv->list, fd, error) >= 0;
 326 }