glib/gio/gunixfdmessage.c

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/* GIO - GLib Input, Output and Streaming Library
*
* Copyright © 2009 Codethink Limited
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation; either
* version 2.1 of the License, or (at your option) any later version.
*
* See the included COPYING file for more information.
*
* Authors: Ryan Lortie <desrt@desrt.ca>
*/
/**
* SECTION:gunixfdmessage
* @title: GUnixFDMessage
* @short_description: A GSocketControlMessage containing a GUnixFDList
* @include: gio/gunixfdmessage.h
* @see_also: #GUnixConnection, #GUnixFDList, #GSocketControlMessage
*
* This #GSocketControlMessage contains a #GUnixFDList.
* It may be sent using g_socket_send_message() and received using
* g_socket_receive_message() over UNIX sockets (ie: sockets in the
* %G_SOCKET_ADDRESS_UNIX family). The file descriptors are copied
* between processes by the kernel.
*
* For an easier way to send and receive file descriptors over
* stream-oriented UNIX sockets, see g_unix_connection_send_fd() and
* g_unix_connection_receive_fd().
*
* Note that `<gio/gunixfdmessage.h>` belongs to the UNIX-specific GIO
* interfaces, thus you have to use the `gio-unix-2.0.pc` pkg-config
* file when using it.
*/
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/**
* GUnixFDMessage:
*
* #GUnixFDMessage is an opaque data structure and can only be accessed
* using the following functions.
**/
#include "config.h"
#include <unistd.h>
#include <string.h>
#include <fcntl.h>
#include <errno.h>
#include "gunixfdmessage.h"
#include "gunixfdlist.h"
#include "gnetworking.h"
#include "gioerror.h"
struct _GUnixFDMessagePrivate
{
GUnixFDList *list;
};
G_DEFINE_TYPE_WITH_PRIVATE (GUnixFDMessage, g_unix_fd_message, G_TYPE_SOCKET_CONTROL_MESSAGE)
static gsize
g_unix_fd_message_get_size (GSocketControlMessage *message)
{
GUnixFDMessage *fd_message = G_UNIX_FD_MESSAGE (message);
return g_unix_fd_list_get_length (fd_message->priv->list) * sizeof (gint);
}
static int
g_unix_fd_message_get_level (GSocketControlMessage *message)
{
return SOL_SOCKET;
}
static int
g_unix_fd_message_get_msg_type (GSocketControlMessage *message)
{
return SCM_RIGHTS;
}
static GSocketControlMessage *
g_unix_fd_message_deserialize (int level,
int type,
gsize size,
gpointer data)
{
GSocketControlMessage *message;
GUnixFDList *list;
gint n, s, i;
gint *fds;
if (level != SOL_SOCKET ||
type != SCM_RIGHTS)
return NULL;
if (size % 4 > 0)
{
g_warning ("Kernel returned non-integral number of fds");
return NULL;
}
fds = data;
n = size / sizeof (gint);
/* Note we probably handled this in gsocket.c already if we're on
* Linux and have MSG_CMSG_CLOEXEC, but this code remains as a fallback
* in case the kernel is too old for MSG_CMSG_CLOEXEC.
*/
for (i = 0; i < n; i++)
{
int errsv;
do
{
s = fcntl (fds[i], F_SETFD, FD_CLOEXEC);
errsv = errno;
}
while (s < 0 && errsv == EINTR);
if (s < 0)
{
g_warning ("Error setting close-on-exec flag on incoming fd: %s",
g_strerror (errsv));
return NULL;
}
}
list = g_unix_fd_list_new_from_array (fds, n);
message = g_unix_fd_message_new_with_fd_list (list);
g_object_unref (list);
return message;
}
static void
g_unix_fd_message_serialize (GSocketControlMessage *message,
gpointer data)
{
GUnixFDMessage *fd_message = G_UNIX_FD_MESSAGE (message);
const gint *fds;
gint n_fds;
fds = g_unix_fd_list_peek_fds (fd_message->priv->list, &n_fds);
memcpy (data, fds, sizeof (gint) * n_fds);
}
static void
g_unix_fd_message_set_property (GObject *object, guint prop_id,
const GValue *value, GParamSpec *pspec)
{
GUnixFDMessage *message = G_UNIX_FD_MESSAGE (object);
g_assert (message->priv->list == NULL);
g_assert_cmpint (prop_id, ==, 1);
message->priv->list = g_value_dup_object (value);
if (message->priv->list == NULL)
message->priv->list = g_unix_fd_list_new ();
}
/**
* g_unix_fd_message_get_fd_list:
* @message: a #GUnixFDMessage
*
* Gets the #GUnixFDList contained in @message. This function does not
* return a reference to the caller, but the returned list is valid for
* the lifetime of @message.
*
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* Returns: (transfer none): the #GUnixFDList from @message
*
* Since: 2.24
**/
GUnixFDList *
g_unix_fd_message_get_fd_list (GUnixFDMessage *message)
{
return message->priv->list;
}
static void
g_unix_fd_message_get_property (GObject *object, guint prop_id,
GValue *value, GParamSpec *pspec)
{
GUnixFDMessage *message = G_UNIX_FD_MESSAGE (object);
g_assert_cmpint (prop_id, ==, 1);
g_value_set_object (value, g_unix_fd_message_get_fd_list (message));
}
static void
g_unix_fd_message_init (GUnixFDMessage *message)
{
message->priv = g_unix_fd_message_get_instance_private (message);
}
static void
g_unix_fd_message_finalize (GObject *object)
{
GUnixFDMessage *message = G_UNIX_FD_MESSAGE (object);
g_object_unref (message->priv->list);
G_OBJECT_CLASS (g_unix_fd_message_parent_class)
->finalize (object);
}
static void
g_unix_fd_message_class_init (GUnixFDMessageClass *class)
{
GSocketControlMessageClass *scm_class = G_SOCKET_CONTROL_MESSAGE_CLASS (class);
GObjectClass *object_class = G_OBJECT_CLASS (class);
scm_class->get_size = g_unix_fd_message_get_size;
scm_class->get_level = g_unix_fd_message_get_level;
scm_class->get_type = g_unix_fd_message_get_msg_type;
scm_class->serialize = g_unix_fd_message_serialize;
scm_class->deserialize = g_unix_fd_message_deserialize;
object_class->finalize = g_unix_fd_message_finalize;
object_class->set_property = g_unix_fd_message_set_property;
object_class->get_property = g_unix_fd_message_get_property;
g_object_class_install_property (object_class, 1,
g_param_spec_object ("fd-list", "file descriptor list",
"The GUnixFDList object to send with the message",
G_TYPE_UNIX_FD_LIST, G_PARAM_STATIC_STRINGS |
G_PARAM_READWRITE | G_PARAM_CONSTRUCT_ONLY));
}
/**
* g_unix_fd_message_new:
*
* Creates a new #GUnixFDMessage containing an empty file descriptor
* list.
*
* Returns: a new #GUnixFDMessage
*
* Since: 2.22
**/
GSocketControlMessage *
g_unix_fd_message_new (void)
{
return g_object_new (G_TYPE_UNIX_FD_MESSAGE, NULL);
}
/**
* g_unix_fd_message_new_with_fd_list:
* @fd_list: a #GUnixFDList
*
* Creates a new #GUnixFDMessage containing @list.
*
* Returns: a new #GUnixFDMessage
*
* Since: 2.24
**/
GSocketControlMessage *
g_unix_fd_message_new_with_fd_list (GUnixFDList *fd_list)
{
return g_object_new (G_TYPE_UNIX_FD_MESSAGE,
"fd-list", fd_list,
NULL);
}
/**
* g_unix_fd_message_steal_fds:
* @message: a #GUnixFDMessage
* @length: (out) (optional): pointer to the length of the returned
* array, or %NULL
*
* Returns the array of file descriptors that is contained in this
* object.
*
* After this call, the descriptors are no longer contained in
* @message. Further calls will return an empty list (unless more
* descriptors have been added).
*
* The return result of this function must be freed with g_free().
* The caller is also responsible for closing all of the file
* descriptors.
*
* If @length is non-%NULL then it is set to the number of file
* descriptors in the returned array. The returned array is also
* terminated with -1.
*
* This function never returns %NULL. In case there are no file
* descriptors contained in @message, an empty array is returned.
*
* Returns: (array length=length) (transfer full): an array of file
* descriptors
*
* Since: 2.22
**/
gint *
g_unix_fd_message_steal_fds (GUnixFDMessage *message,
gint *length)
{
g_return_val_if_fail (G_UNIX_FD_MESSAGE (message), NULL);
return g_unix_fd_list_steal_fds (message->priv->list, length);
}
/**
* g_unix_fd_message_append_fd:
* @message: a #GUnixFDMessage
* @fd: a valid open file descriptor
* @error: a #GError pointer
*
* Adds a file descriptor to @message.
*
* The file descriptor is duplicated using dup(). You keep your copy
* of the descriptor and the copy contained in @message will be closed
* when @message is finalized.
*
* A possible cause of failure is exceeding the per-process or
* system-wide file descriptor limit.
*
* Returns: %TRUE in case of success, else %FALSE (and @error is set)
*
* Since: 2.22
**/
gboolean
g_unix_fd_message_append_fd (GUnixFDMessage *message,
gint fd,
GError **error)
{
g_return_val_if_fail (G_UNIX_FD_MESSAGE (message), FALSE);
return g_unix_fd_list_append (message->priv->list, fd, error) >= 0;
}