glib/gio/gunixfdlist.c

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/* GIO - GLib Input, Output and Streaming Library
*
* Copyright © 2009 Codethink Limited
*
* This program 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 of the licence or (at
* your option) any later version.
*
* See the included COPYING file for more information.
*
* Authors: Ryan Lortie <desrt@desrt.ca>
*/
/**
* SECTION: gunixfdlist
* @title: GUnixFDList
* @short_description: An object containing a set of UNIX file descriptors
* @include: gio/gunixfdlist.h
* @see_also: #GUnixFDMessage
*
* A #GUnixFDList contains a list of file descriptors. It owns the file
* descriptors that it contains, closing them when finalized.
*
* It may be wrapped in a #GUnixFDMessage and sent over a #GSocket in
* the %G_SOCKET_ADDRESS_UNIX family by using g_socket_send_message()
* and received using g_socket_receive_message().
*
* Note that <filename>&lt;gio/gunixfdlist.h&gt;</filename> belongs to
* the UNIX-specific GIO interfaces, thus you have to use the
* <filename>gio-unix-2.0.pc</filename> pkg-config file when using it.
*/
#define _GNU_SOURCE /* for F_DUPFD_CLOEXEC */
#include "config.h"
#include <sys/types.h>
#include <sys/socket.h>
#include <unistd.h>
#include <fcntl.h>
#include <string.h>
#include <errno.h>
#include "gunixfdlist.h"
#include "gioerror.h"
G_DEFINE_TYPE (GUnixFDList, g_unix_fd_list, G_TYPE_OBJECT)
struct _GUnixFDListPrivate
{
gint *fds;
gint nfd;
};
static void
g_unix_fd_list_init (GUnixFDList *list)
{
list->priv = G_TYPE_INSTANCE_GET_PRIVATE (list,
G_TYPE_UNIX_FD_LIST,
GUnixFDListPrivate);
}
static void
g_unix_fd_list_finalize (GObject *object)
{
GUnixFDList *list = G_UNIX_FD_LIST (object);
gint i;
for (i = 0; i < list->priv->nfd; i++)
close (list->priv->fds[i]);
g_free (list->priv->fds);
G_OBJECT_CLASS (g_unix_fd_list_parent_class)
->finalize (object);
}
static void
g_unix_fd_list_class_init (GUnixFDListClass *class)
{
GObjectClass *object_class = G_OBJECT_CLASS (class);
g_type_class_add_private (class, sizeof (GUnixFDListPrivate));
object_class->finalize = g_unix_fd_list_finalize;
}
static int
dup_close_on_exec_fd (gint fd,
GError **error)
{
gint new_fd;
gint s;
#ifdef F_DUPFD_CLOEXEC
do
new_fd = fcntl (fd, F_DUPFD_CLOEXEC, 0l);
while (new_fd < 0 && (errno == EINTR));
if (new_fd >= 0)
return new_fd;
/* if that didn't work (new libc/old kernel?), try it the other way. */
#endif
do
new_fd = dup (fd);
while (new_fd < 0 && (errno == EINTR));
if (new_fd < 0)
{
int saved_errno = errno;
g_set_error (error, G_IO_ERROR,
g_io_error_from_errno (saved_errno),
"dup: %s", g_strerror (saved_errno));
close (new_fd);
return -1;
}
do
{
s = fcntl (new_fd, F_GETFD);
if (s >= 0)
s = fcntl (new_fd, F_SETFD, (long) (s | FD_CLOEXEC));
}
while (s < 0 && (errno == EINTR));
if (s < 0)
{
int saved_errno = errno;
g_set_error (error, G_IO_ERROR,
g_io_error_from_errno (saved_errno),
"fcntl: %s", g_strerror (saved_errno));
close (new_fd);
return -1;
}
return new_fd;
}
/**
* g_unix_fd_list_new:
*
* Creates a new #GUnixFDList containing no file descriptors.
*
* Returns: a new #GUnixFDList
*
* Since: 2.24
**/
GUnixFDList *
g_unix_fd_list_new (void)
{
return g_object_new (G_TYPE_UNIX_FD_LIST, NULL);
}
/**
* g_unix_fd_list_new_from_array:
* @fds: the initial list of file descriptors
* @n_fds: the length of #fds, or -1
*
* Creates a new #GUnixFDList containing the file descriptors given in
* @fds. The file descriptors become the property of the new list and
* may no longer be used by the caller. The array itself is owned by
* the caller.
*
* Each file descriptor in the array should be set to close-on-exec.
*
* If @n_fds is -1 then @fds must be terminated with -1.
*
* Returns: a new #GUnixFDList
*
* Since: 2.24
**/
GUnixFDList *
g_unix_fd_list_new_from_array (const gint *fds,
gint n_fds)
{
GUnixFDList *list;
g_return_val_if_fail (fds != NULL || n_fds == 0, NULL);
if (n_fds == -1)
for (n_fds = 0; fds[n_fds] != -1; n_fds++);
list = g_object_new (G_TYPE_UNIX_FD_LIST, NULL);
list->priv->fds = g_new (gint, n_fds + 1);
list->priv->nfd = n_fds;
memcpy (list->priv->fds, fds, sizeof (gint) * n_fds);
list->priv->fds[n_fds] = -1;
return list;
}
/**
* g_unix_fd_list_steal_fds:
* @list: a #GUnixFDList
* @length: 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
* @list. 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. The file descriptors in the array are set to
* close-on-exec.
*
* 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 @list, an empty array is returned.
*
* Returns: an array of file descriptors
*
* Since: 2.24
*/
gint *
g_unix_fd_list_steal_fds (GUnixFDList *list,
gint *length)
{
gint *result;
g_return_val_if_fail (G_IS_UNIX_FD_LIST (list), NULL);
/* will be true for fresh object or if we were just called */
if (list->priv->fds == NULL)
{
list->priv->fds = g_new (gint, 1);
list->priv->fds[0] = -1;
list->priv->nfd = 0;
}
if (length)
*length = list->priv->nfd;
result = list->priv->fds;
list->priv->fds = NULL;
list->priv->nfd = 0;
return result;
}
/**
* g_unix_fd_list_peek_fds:
* @list: a #GUnixFDList
* @length: 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 remain the property of @list. The
* caller must not close them and must not free the array. The array is
* valid only until @list is changed in any way.
*
* 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 @list, an empty array is returned.
*
* Returns: an array of file descriptors
*
* Since: 2.24
*/
const gint *
g_unix_fd_list_peek_fds (GUnixFDList *list,
gint *length)
{
g_return_val_if_fail (G_IS_UNIX_FD_LIST (list), NULL);
/* will be true for fresh object or if steal() was just called */
if (list->priv->fds == NULL)
{
list->priv->fds = g_new (gint, 1);
list->priv->fds[0] = -1;
list->priv->nfd = 0;
}
if (length)
*length = list->priv->nfd;
return list->priv->fds;
}
/**
* g_unix_fd_list_append:
* @list: a #GUnixFDList
* @fd: a valid open file descriptor
* @error: a #GError pointer
*
* Adds a file descriptor to @list.
*
* The file descriptor is duplicated using dup(). You keep your copy
* of the descriptor and the copy contained in @list will be closed
* when @list is finalized.
*
* A possible cause of failure is exceeding the per-process or
* system-wide file descriptor limit.
*
* The index of the file descriptor in the list is returned. If you use
* this index with g_unix_fd_list_get() then you will receive back a
* duplicated copy of the same file descriptor.
*
* Returns: the index of the appended fd in case of success, else -1
* (and @error is set)
*
* Since: 2.24
*/
gint
g_unix_fd_list_append (GUnixFDList *list,
gint fd,
GError **error)
{
gint new_fd;
g_return_val_if_fail (G_IS_UNIX_FD_LIST (list), -1);
g_return_val_if_fail (fd >= 0, -1);
g_return_val_if_fail (error == NULL || *error == NULL, -1);
if ((new_fd = dup_close_on_exec_fd (fd, error)) < 0)
return -1;
list->priv->fds = g_realloc (list->priv->fds,
sizeof (gint) *
(list->priv->nfd + 2));
list->priv->fds[list->priv->nfd++] = new_fd;
list->priv->fds[list->priv->nfd] = -1;
return list->priv->nfd - 1;
}
/**
* g_unix_fd_list_get:
* @list: a #GUnixFDList
* @index_: the index into the list
* @error: a #GError pointer
*
* Gets a file descriptor out of @list.
*
* @index_ specifies the index of the file descriptor to get. It is a
* programmer error for @index_ to be out of range; see
* g_unix_fd_list_get_length().
*
* The file descriptor is duplicated using dup() and set as
* close-on-exec before being returned. You must call close() on it
* when you are done.
*
* A possible cause of failure is exceeding the per-process or
* system-wide file descriptor limit.
*
* Returns: the file descriptor, or -1 in case of error
*
* Since: 2.24
**/
gint
g_unix_fd_list_get (GUnixFDList *list,
gint index_,
GError **error)
{
g_return_val_if_fail (G_IS_UNIX_FD_LIST (list), -1);
g_return_val_if_fail (index_ < list->priv->nfd, -1);
g_return_val_if_fail (error == NULL || *error == NULL, -1);
return dup_close_on_exec_fd (list->priv->fds[index_], error);
}
/**
* g_unix_fd_list_get_length:
* @list: a #GUnixFDList
*
* Gets the length of @list (ie: the number of file descriptors
* contained within).
*
* Returns: the length of @list
*
* Since: 2.24
**/
gint
g_unix_fd_list_get_length (GUnixFDList *list)
{
g_return_val_if_fail (G_IS_UNIX_FD_LIST (list), 0);
return list->priv->nfd;
}