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/* Hook for making file descriptor functions close(), ioctl() extensible.
Copyright (C) 2009-2023 Free Software Foundation, Inc.
Written by Bruno Haible <bruno@clisp.org>, 2009.
This file 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.
This file is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU Lesser General Public License for more details.
You should have received a copy of the GNU Lesser General Public License
along with this program. If not, see <https://www.gnu.org/licenses/>. */
#include <config.h>
/* Specification. */
#include "fd-hook.h"
#include <stdlib.h>
/* Currently, this entire code is only needed for the handling of sockets
on native Windows platforms. */
#if WINDOWS_SOCKETS
/* The first and last link in the doubly linked list.
Initially the list is empty. */
static struct fd_hook anchor = { &anchor, &anchor, NULL, NULL };
int
execute_close_hooks (const struct fd_hook *remaining_list, gl_close_fn primary,
int fd)
{
if (remaining_list == &anchor)
/* End of list reached. */
return primary (fd);
else
return remaining_list->private_close_fn (remaining_list->private_next,
primary, fd);
}
int
execute_all_close_hooks (gl_close_fn primary, int fd)
{
return execute_close_hooks (anchor.private_next, primary, fd);
}
int
execute_ioctl_hooks (const struct fd_hook *remaining_list, gl_ioctl_fn primary,
int fd, int request, void *arg)
{
if (remaining_list == &anchor)
/* End of list reached. */
return primary (fd, request, arg);
else
return remaining_list->private_ioctl_fn (remaining_list->private_next,
primary, fd, request, arg);
}
int
execute_all_ioctl_hooks (gl_ioctl_fn primary,
int fd, int request, void *arg)
{
return execute_ioctl_hooks (anchor.private_next, primary, fd, request, arg);
}
void
register_fd_hook (close_hook_fn close_hook, ioctl_hook_fn ioctl_hook, struct fd_hook *link)
{
if (close_hook == NULL)
close_hook = execute_close_hooks;
if (ioctl_hook == NULL)
ioctl_hook = execute_ioctl_hooks;
if (link->private_next == NULL && link->private_prev == NULL)
{
/* Add the link to the doubly linked list. */
link->private_next = anchor.private_next;
link->private_prev = &anchor;
link->private_close_fn = close_hook;
link->private_ioctl_fn = ioctl_hook;
anchor.private_next->private_prev = link;
anchor.private_next = link;
}
else
{
/* The link is already in use. */
if (link->private_close_fn != close_hook
|| link->private_ioctl_fn != ioctl_hook)
abort ();
}
}
void
unregister_fd_hook (struct fd_hook *link)
{
struct fd_hook *next = link->private_next;
struct fd_hook *prev = link->private_prev;
if (next != NULL && prev != NULL)
{
/* The link is in use. Remove it from the doubly linked list. */
prev->private_next = next;
next->private_prev = prev;
/* Clear the link, to mark it unused. */
link->private_next = NULL;
link->private_prev = NULL;
link->private_close_fn = NULL;
link->private_ioctl_fn = NULL;
}
}
#endif
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