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 `<gio/gunixfdmessage.h>` belongs to the UNIX-specific GIO
  33  * interfaces, thus you have to use the `gio-unix-2.0.pc` pkg-config
  34  * file when using it.
  35  */
  36
  37 /**
  38  * GUnixFDMessage:
  39  *
  40  * #GUnixFDMessage is an opaque data structure and can only be accessed
  41  * using the following functions.
  42  **/
  43
  44 #include "config.h"
  45
  46 #include <unistd.h>
  47 #include <string.h>
  48 #include <fcntl.h>
  49 #include <errno.h>
  50
  51 #include "gunixfdmessage.h"
  52 #include "gunixfdlist.h"
  53 #include "gnetworking.h"
  54 #include "gioerror.h"
  55
  56 struct _GUnixFDMessagePrivate
  57 {
  58   GUnixFDList *list;
  59 };
  60
  61 G_DEFINE_TYPE_WITH_PRIVATE (GUnixFDMessage, g_unix_fd_message, G_TYPE_SOCKET_CONTROL_MESSAGE)
  62
  63 static gsize
  64 g_unix_fd_message_get_size (GSocketControlMessage *message)
  65 {
  66   GUnixFDMessage *fd_message = G_UNIX_FD_MESSAGE (message);
  67
  68   return g_unix_fd_list_get_length (fd_message->priv->list) * sizeof (gint);
  69 }
  70
  71 static int
  72 g_unix_fd_message_get_level (GSocketControlMessage *message)
  73 {
  74   return SOL_SOCKET;
  75 }
  76
  77 static int
  78 g_unix_fd_message_get_msg_type (GSocketControlMessage *message)
  79 {
  80   return SCM_RIGHTS;
  81 }
  82
  83 static GSocketControlMessage *
  84 g_unix_fd_message_deserialize (int      level,
  85                                int      type,
  86                                gsize    size,
  87                                gpointer data)
  88 {
  89   GSocketControlMessage *message;
  90   GUnixFDList *list;
  91   gint n, s, i;
  92   gint *fds;
  93
  94   if (level != SOL_SOCKET ||
  95       type != SCM_RIGHTS)
  96     return NULL;
  97
  98   if (size % 4 > 0)
  99     {
 100       g_warning ("Kernel returned non-integral number of fds");
 101       return NULL;
 102     }
 103
 104   fds = data;
 105   n = size / sizeof (gint);
 106
 107   /* Note we probably handled this in gsocket.c already if we're on
 108    * Linux and have MSG_CMSG_CLOEXEC, but this code remains as a fallback
 109    * in case the kernel is too old for MSG_CMSG_CLOEXEC.
 110    */
 111   for (i = 0; i < n; i++)
 112     {
 113       do
 114         s = fcntl (fds[i], F_SETFD, FD_CLOEXEC);
 115       while (s < 0 && errno == EINTR);
 116
 117       if (s < 0)
 118         {
 119           g_warning ("Error setting close-on-exec flag on incoming fd: %s",
 120                      g_strerror (errno));
 121           return NULL;
 122         }
 123     }
 124
 125   list = g_unix_fd_list_new_from_array (fds, n);
 126   message = g_unix_fd_message_new_with_fd_list (list);
 127   g_object_unref (list);
 128
 129   return message;
 130 }
 131
 132 static void
 133 g_unix_fd_message_serialize (GSocketControlMessage *message,
 134                              gpointer               data)
 135 {
 136   GUnixFDMessage *fd_message = G_UNIX_FD_MESSAGE (message);
 137   const gint *fds;
 138   gint n_fds;
 139
 140   fds = g_unix_fd_list_peek_fds (fd_message->priv->list, &n_fds);
 141   memcpy (data, fds, sizeof (gint) * n_fds);
 142 }
 143
 144 static void
 145 g_unix_fd_message_set_property (GObject *object, guint prop_id,
 146                                 const GValue *value, GParamSpec *pspec)
 147 {
 148   GUnixFDMessage *message = G_UNIX_FD_MESSAGE (object);
 149
 150   g_assert (message->priv->list == NULL);
 151   g_assert_cmpint (prop_id, ==, 1);
 152
 153   message->priv->list = g_value_dup_object (value);
 154
 155   if (message->priv->list == NULL)
 156     message->priv->list = g_unix_fd_list_new ();
 157 }
 158
 159 /**
 160  * g_unix_fd_message_get_fd_list:
 161  * @message: a #GUnixFDMessage
 162  *
 163  * Gets the #GUnixFDList contained in @message.  This function does not
 164  * return a reference to the caller, but the returned list is valid for
 165  * the lifetime of @message.
 166  *
 167  * Returns: (transfer none): the #GUnixFDList from @message
 168  *
 169  * Since: 2.24
 170  **/
 171 GUnixFDList *
 172 g_unix_fd_message_get_fd_list (GUnixFDMessage *message)
 173 {
 174   return message->priv->list;
 175 }
 176
 177 static void
 178 g_unix_fd_message_get_property (GObject *object, guint prop_id,
 179                                 GValue *value, GParamSpec *pspec)
 180 {
 181   GUnixFDMessage *message = G_UNIX_FD_MESSAGE (object);
 182
 183   g_assert_cmpint (prop_id, ==, 1);
 184
 185   g_value_set_object (value, g_unix_fd_message_get_fd_list (message));
 186 }
 187
 188 static void
 189 g_unix_fd_message_init (GUnixFDMessage *message)
 190 {
 191   message->priv = g_unix_fd_message_get_instance_private (message);
 192 }
 193
 194 static void
 195 g_unix_fd_message_finalize (GObject *object)
 196 {
 197   GUnixFDMessage *message = G_UNIX_FD_MESSAGE (object);
 198
 199   g_object_unref (message->priv->list);
 200
 201   G_OBJECT_CLASS (g_unix_fd_message_parent_class)
 202     ->finalize (object);
 203 }
 204
 205 static void
 206 g_unix_fd_message_class_init (GUnixFDMessageClass *class)
 207 {
 208   GSocketControlMessageClass *scm_class = G_SOCKET_CONTROL_MESSAGE_CLASS (class);
 209   GObjectClass *object_class = G_OBJECT_CLASS (class);
 210
 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) (optional): 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 }