gio/gunixfdmessage.c

   1 /* GIO - GLib Input, Output and Streaming Library
   2  *
   3  * Copyright © 2009 Codethink Limited
   4  *
   5  * This library is free software; you can redistribute it and/or
   6  * modify it under the terms of the GNU Lesser General Public
   7  * License as published by the Free Software Foundation; either
   8  * version 2.1 of the License, or (at 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       int errsv;
 114
 115       do
 116         {
 117           s = fcntl (fds[i], F_SETFD, FD_CLOEXEC);
 118           errsv = errno;
 119         }
 120       while (s < 0 && errsv == EINTR);
 121
 122       if (s < 0)
 123         {
 124           g_warning ("Error setting close-on-exec flag on incoming fd: %s",
 125                      g_strerror (errsv));
 126           return NULL;
 127         }
 128     }
 129
 130   list = g_unix_fd_list_new_from_array (fds, n);
 131   message = g_unix_fd_message_new_with_fd_list (list);
 132   g_object_unref (list);
 133
 134   return message;
 135 }
 136
 137 static void
 138 g_unix_fd_message_serialize (GSocketControlMessage *message,
 139                              gpointer               data)
 140 {
 141   GUnixFDMessage *fd_message = G_UNIX_FD_MESSAGE (message);
 142   const gint *fds;
 143   gint n_fds;
 144
 145   fds = g_unix_fd_list_peek_fds (fd_message->priv->list, &n_fds);
 146   memcpy (data, fds, sizeof (gint) * n_fds);
 147 }
 148
 149 static void
 150 g_unix_fd_message_set_property (GObject *object, guint prop_id,
 151                                 const GValue *value, GParamSpec *pspec)
 152 {
 153   GUnixFDMessage *message = G_UNIX_FD_MESSAGE (object);
 154
 155   g_assert (message->priv->list == NULL);
 156   g_assert_cmpint (prop_id, ==, 1);
 157
 158   message->priv->list = g_value_dup_object (value);
 159
 160   if (message->priv->list == NULL)
 161     message->priv->list = g_unix_fd_list_new ();
 162 }
 163
 164 /**
 165  * g_unix_fd_message_get_fd_list:
 166  * @message: a #GUnixFDMessage
 167  *
 168  * Gets the #GUnixFDList contained in @message.  This function does not
 169  * return a reference to the caller, but the returned list is valid for
 170  * the lifetime of @message.
 171  *
 172  * Returns: (transfer none): the #GUnixFDList from @message
 173  *
 174  * Since: 2.24
 175  **/
 176 GUnixFDList *
 177 g_unix_fd_message_get_fd_list (GUnixFDMessage *message)
 178 {
 179   return message->priv->list;
 180 }
 181
 182 static void
 183 g_unix_fd_message_get_property (GObject *object, guint prop_id,
 184                                 GValue *value, GParamSpec *pspec)
 185 {
 186   GUnixFDMessage *message = G_UNIX_FD_MESSAGE (object);
 187
 188   g_assert_cmpint (prop_id, ==, 1);
 189
 190   g_value_set_object (value, g_unix_fd_message_get_fd_list (message));
 191 }
 192
 193 static void
 194 g_unix_fd_message_init (GUnixFDMessage *message)
 195 {
 196   message->priv = g_unix_fd_message_get_instance_private (message);
 197 }
 198
 199 static void
 200 g_unix_fd_message_finalize (GObject *object)
 201 {
 202   GUnixFDMessage *message = G_UNIX_FD_MESSAGE (object);
 203
 204   g_object_unref (message->priv->list);
 205
 206   G_OBJECT_CLASS (g_unix_fd_message_parent_class)
 207     ->finalize (object);
 208 }
 209
 210 static void
 211 g_unix_fd_message_class_init (GUnixFDMessageClass *class)
 212 {
 213   GSocketControlMessageClass *scm_class = G_SOCKET_CONTROL_MESSAGE_CLASS (class);
 214   GObjectClass *object_class = G_OBJECT_CLASS (class);
 215
 216   scm_class->get_size = g_unix_fd_message_get_size;
 217   scm_class->get_level = g_unix_fd_message_get_level;
 218   scm_class->get_type = g_unix_fd_message_get_msg_type;
 219   scm_class->serialize = g_unix_fd_message_serialize;
 220   scm_class->deserialize = g_unix_fd_message_deserialize;
 221   object_class->finalize = g_unix_fd_message_finalize;
 222   object_class->set_property = g_unix_fd_message_set_property;
 223   object_class->get_property = g_unix_fd_message_get_property;
 224
 225   g_object_class_install_property (object_class, 1,
 226     g_param_spec_object ("fd-list", "file descriptor list",
 227                          "The GUnixFDList object to send with the message",
 228                          G_TYPE_UNIX_FD_LIST, G_PARAM_STATIC_STRINGS |
 229                          G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY));
 230 }
 231
 232 /**
 233  * g_unix_fd_message_new:
 234  *
 235  * Creates a new #GUnixFDMessage containing an empty file descriptor
 236  * list.
 237  *
 238  * Returns: a new #GUnixFDMessage
 239  *
 240  * Since: 2.22
 241  **/
 242 GSocketControlMessage *
 243 g_unix_fd_message_new (void)
 244 {
 245   return g_object_new (G_TYPE_UNIX_FD_MESSAGE, NULL);
 246 }
 247
 248 /**
 249  * g_unix_fd_message_new_with_fd_list:
 250  * @fd_list: a #GUnixFDList
 251  *
 252  * Creates a new #GUnixFDMessage containing @list.
 253  *
 254  * Returns: a new #GUnixFDMessage
 255  *
 256  * Since: 2.24
 257  **/
 258 GSocketControlMessage *
 259 g_unix_fd_message_new_with_fd_list (GUnixFDList *fd_list)
 260 {
 261   return g_object_new (G_TYPE_UNIX_FD_MESSAGE,
 262                        "fd-list", fd_list,
 263                        NULL);
 264 }
 265
 266 /**
 267  * g_unix_fd_message_steal_fds:
 268  * @message: a #GUnixFDMessage
 269  * @length: (out) (optional): pointer to the length of the returned
 270  *     array, or %NULL
 271  *
 272  * Returns the array of file descriptors that is contained in this
 273  * object.
 274  *
 275  * After this call, the descriptors are no longer contained in
 276  * @message. Further calls will return an empty list (unless more
 277  * descriptors have been added).
 278  *
 279  * The return result of this function must be freed with g_free().
 280  * The caller is also responsible for closing all of the file
 281  * descriptors.
 282  *
 283  * If @length is non-%NULL then it is set to the number of file
 284  * descriptors in the returned array. The returned array is also
 285  * terminated with -1.
 286  *
 287  * This function never returns %NULL. In case there are no file
 288  * descriptors contained in @message, an empty array is returned.
 289  *
 290  * Returns: (array length=length) (transfer full): an array of file
 291  *     descriptors
 292  *
 293  * Since: 2.22
 294  **/
 295 gint *
 296 g_unix_fd_message_steal_fds (GUnixFDMessage *message,
 297                              gint           *length)
 298 {
 299   g_return_val_if_fail (G_UNIX_FD_MESSAGE (message), NULL);
 300
 301   return g_unix_fd_list_steal_fds (message->priv->list, length);
 302 }
 303
 304 /**
 305  * g_unix_fd_message_append_fd:
 306  * @message: a #GUnixFDMessage
 307  * @fd: a valid open file descriptor
 308  * @error: a #GError pointer
 309  *
 310  * Adds a file descriptor to @message.
 311  *
 312  * The file descriptor is duplicated using dup(). You keep your copy
 313  * of the descriptor and the copy contained in @message will be closed
 314  * when @message is finalized.
 315  *
 316  * A possible cause of failure is exceeding the per-process or
 317  * system-wide file descriptor limit.
 318  *
 319  * Returns: %TRUE in case of success, else %FALSE (and @error is set)
 320  *
 321  * Since: 2.22
 322  **/
 323 gboolean
 324 g_unix_fd_message_append_fd (GUnixFDMessage  *message,
 325                              gint             fd,
 326                              GError         **error)
 327 {
 328   g_return_val_if_fail (G_UNIX_FD_MESSAGE (message), FALSE);
 329
 330   return g_unix_fd_list_append (message->priv->list, fd, error) >= 0;
 331 }