1 /* GIO - GLib Input, Output and Streaming Library
2 *
3 * Copyright © 2009 Codethink Limited
4 *
5 * SPDX-License-Identifier: LGPL-2.1-or-later
6 *
7 * This library is free software; you can redistribute it and/or
8 * modify it under the terms of the GNU Lesser General Public
9 * License as published by the Free Software Foundation; either
10 * version 2.1 of the License, or (at your option) any later version.
11 *
12 * See the included COPYING file for more information.
13 *
14 * Authors: Ryan Lortie <desrt@desrt.ca>
15 */
16
17 /**
18 * GUnixFDMessage:
19 *
20 * This [class@Gio.SocketControlMessage] contains a [class@Gio.UnixFDList].
21 * It may be sent using [method@Gio.Socket.send_message] and received using
22 * [method@Gio.Socket.receive_message] over UNIX sockets (ie: sockets in the
23 * `G_SOCKET_FAMILY_UNIX` family). The file descriptors are copied
24 * between processes by the kernel.
25 *
26 * For an easier way to send and receive file descriptors over
27 * stream-oriented UNIX sockets, see [method@Gio.UnixConnection.send_fd] and
28 * [method@Gio.UnixConnection.receive_fd].
29 *
30 * Note that `<gio/gunixfdmessage.h>` belongs to the UNIX-specific GIO
31 * interfaces, thus you have to use the `gio-unix-2.0.pc` pkg-config
32 * file when using it.
33 */
34
35 #include "config.h"
36
37 #include <unistd.h>
38 #include <string.h>
39 #include <fcntl.h>
40 #include <errno.h>
41
42 #include "gunixfdmessage.h"
43 #include "gunixfdlist.h"
44 #include "gnetworking.h"
45 #include "gioerror.h"
46
47 struct _GUnixFDMessagePrivate
48 {
49 GUnixFDList *list;
50 };
51
52 G_DEFINE_TYPE_WITH_PRIVATE (GUnixFDMessage, g_unix_fd_message, G_TYPE_SOCKET_CONTROL_MESSAGE)
53
54 static gsize
55 g_unix_fd_message_get_size (GSocketControlMessage *message)
56 {
57 GUnixFDMessage *fd_message = G_UNIX_FD_MESSAGE (message);
58
59 return g_unix_fd_list_get_length (fd_message->priv->list) * sizeof (gint);
60 }
61
62 static int
63 g_unix_fd_message_get_level (GSocketControlMessage *message)
64 {
65 return SOL_SOCKET;
66 }
67
68 static int
69 g_unix_fd_message_get_msg_type (GSocketControlMessage *message)
70 {
71 return SCM_RIGHTS;
72 }
73
74 static GSocketControlMessage *
75 g_unix_fd_message_deserialize (int level,
76 int type,
77 gsize size,
78 gpointer data)
79 {
80 GSocketControlMessage *message;
81 GUnixFDList *list;
82 gint n, s, i;
83 gint *fds;
84
85 if (level != SOL_SOCKET ||
86 type != SCM_RIGHTS)
87 return NULL;
88
89 if (size % 4 > 0)
90 {
91 g_warning ("Kernel returned non-integral number of fds");
92 return NULL;
93 }
94
95 fds = data;
96 n = size / sizeof (gint);
97
98 /* Note we probably handled this in gsocket.c already if we're on
99 * Linux and have MSG_CMSG_CLOEXEC, but this code remains as a fallback
100 * in case the kernel is too old for MSG_CMSG_CLOEXEC.
101 */
102 for (i = 0; i < n; i++)
103 {
104 int errsv;
105
106 do
107 {
108 s = fcntl (fds[i], F_SETFD, FD_CLOEXEC);
109 errsv = errno;
110 }
111 while (s < 0 && errsv == EINTR);
112
113 if (s < 0)
114 {
115 g_warning ("Error setting close-on-exec flag on incoming fd: %s",
116 g_strerror (errsv));
117 return NULL;
118 }
119 }
120
121 list = g_unix_fd_list_new_from_array (fds, n);
122 message = g_unix_fd_message_new_with_fd_list (list);
123 g_object_unref (list);
124
125 return message;
126 }
127
128 static void
129 g_unix_fd_message_serialize (GSocketControlMessage *message,
130 gpointer data)
131 {
132 GUnixFDMessage *fd_message = G_UNIX_FD_MESSAGE (message);
133 const gint *fds;
134 gint n_fds;
135
136 fds = g_unix_fd_list_peek_fds (fd_message->priv->list, &n_fds);
137 memcpy (data, fds, sizeof (gint) * n_fds);
138 }
139
140 static void
141 g_unix_fd_message_set_property (GObject *object, guint prop_id,
142 const GValue *value, GParamSpec *pspec)
143 {
144 GUnixFDMessage *message = G_UNIX_FD_MESSAGE (object);
145
146 g_assert (message->priv->list == NULL);
147 g_assert_cmpint (prop_id, ==, 1);
148
149 message->priv->list = g_value_dup_object (value);
150
151 if (message->priv->list == NULL)
152 message->priv->list = g_unix_fd_list_new ();
153 }
154
155 /**
156 * g_unix_fd_message_get_fd_list:
157 * @message: a #GUnixFDMessage
158 *
159 * Gets the #GUnixFDList contained in @message. This function does not
160 * return a reference to the caller, but the returned list is valid for
161 * the lifetime of @message.
162 *
163 * Returns: (transfer none): the #GUnixFDList from @message
164 *
165 * Since: 2.24
166 **/
167 GUnixFDList *
168 g_unix_fd_message_get_fd_list (GUnixFDMessage *message)
169 {
170 return message->priv->list;
171 }
172
173 static void
174 g_unix_fd_message_get_property (GObject *object, guint prop_id,
175 GValue *value, GParamSpec *pspec)
176 {
177 GUnixFDMessage *message = G_UNIX_FD_MESSAGE (object);
178
179 g_assert_cmpint (prop_id, ==, 1);
180
181 g_value_set_object (value, g_unix_fd_message_get_fd_list (message));
182 }
183
184 static void
185 g_unix_fd_message_init (GUnixFDMessage *message)
186 {
187 message->priv = g_unix_fd_message_get_instance_private (message);
188 }
189
190 static void
191 g_unix_fd_message_finalize (GObject *object)
192 {
193 GUnixFDMessage *message = G_UNIX_FD_MESSAGE (object);
194
195 g_object_unref (message->priv->list);
196
197 G_OBJECT_CLASS (g_unix_fd_message_parent_class)
198 ->finalize (object);
199 }
200
201 static void
202 g_unix_fd_message_class_init (GUnixFDMessageClass *class)
203 {
204 GSocketControlMessageClass *scm_class = G_SOCKET_CONTROL_MESSAGE_CLASS (class);
205 GObjectClass *object_class = G_OBJECT_CLASS (class);
206
207 scm_class->get_size = g_unix_fd_message_get_size;
208 scm_class->get_level = g_unix_fd_message_get_level;
209 scm_class->get_type = g_unix_fd_message_get_msg_type;
210 scm_class->serialize = g_unix_fd_message_serialize;
211 scm_class->deserialize = g_unix_fd_message_deserialize;
212 object_class->finalize = g_unix_fd_message_finalize;
213 object_class->set_property = g_unix_fd_message_set_property;
214 object_class->get_property = g_unix_fd_message_get_property;
215
216 /**
217 * GUnixFDMessage:fd-list:
218 *
219 * The [class@Gio.UnixFDList] object to send with the message.
220 *
221 * Since: 2.22
222 */
223 g_object_class_install_property (object_class, 1,
224 g_param_spec_object ("fd-list", NULL, NULL,
225 G_TYPE_UNIX_FD_LIST, G_PARAM_STATIC_STRINGS |
226 G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY));
227 }
228
229 /**
230 * g_unix_fd_message_new:
231 *
232 * Creates a new #GUnixFDMessage containing an empty file descriptor
233 * list.
234 *
235 * Returns: a new #GUnixFDMessage
236 *
237 * Since: 2.22
238 **/
239 GSocketControlMessage *
240 g_unix_fd_message_new (void)
241 {
242 return g_object_new (G_TYPE_UNIX_FD_MESSAGE, NULL);
243 }
244
245 /**
246 * g_unix_fd_message_new_with_fd_list:
247 * @fd_list: a #GUnixFDList
248 *
249 * Creates a new #GUnixFDMessage containing @list.
250 *
251 * Returns: a new #GUnixFDMessage
252 *
253 * Since: 2.24
254 **/
255 GSocketControlMessage *
256 g_unix_fd_message_new_with_fd_list (GUnixFDList *fd_list)
257 {
258 return g_object_new (G_TYPE_UNIX_FD_MESSAGE,
259 "fd-list", fd_list,
260 NULL);
261 }
262
263 /**
264 * g_unix_fd_message_steal_fds:
265 * @message: a #GUnixFDMessage
266 * @length: (out) (optional): pointer to the length of the returned
267 * array, or %NULL
268 *
269 * Returns the array of file descriptors that is contained in this
270 * object.
271 *
272 * After this call, the descriptors are no longer contained in
273 * @message. Further calls will return an empty list (unless more
274 * descriptors have been added).
275 *
276 * The return result of this function must be freed with g_free().
277 * The caller is also responsible for closing all of the file
278 * descriptors.
279 *
280 * If @length is non-%NULL then it is set to the number of file
281 * descriptors in the returned array. The returned array is also
282 * terminated with -1.
283 *
284 * This function never returns %NULL. In case there are no file
285 * descriptors contained in @message, an empty array is returned.
286 *
287 * Returns: (array length=length) (transfer full): an array of file
288 * descriptors
289 *
290 * Since: 2.22
291 **/
292 gint *
293 g_unix_fd_message_steal_fds (GUnixFDMessage *message,
294 gint *length)
295 {
296 g_return_val_if_fail (G_UNIX_FD_MESSAGE (message), NULL);
297
298 return g_unix_fd_list_steal_fds (message->priv->list, length);
299 }
300
301 /**
302 * g_unix_fd_message_append_fd:
303 * @message: a #GUnixFDMessage
304 * @fd: a valid open file descriptor
305 * @error: a #GError pointer
306 *
307 * Adds a file descriptor to @message.
308 *
309 * The file descriptor is duplicated using dup(). You keep your copy
310 * of the descriptor and the copy contained in @message will be closed
311 * when @message is finalized.
312 *
313 * A possible cause of failure is exceeding the per-process or
314 * system-wide file descriptor limit.
315 *
316 * Returns: %TRUE in case of success, else %FALSE (and @error is set)
317 *
318 * Since: 2.22
319 **/
320 gboolean
321 g_unix_fd_message_append_fd (GUnixFDMessage *message,
322 gint fd,
323 GError **error)
324 {
325 g_return_val_if_fail (G_UNIX_FD_MESSAGE (message), FALSE);
326
327 return g_unix_fd_list_append (message->priv->list, fd, error) >= 0;
328 }