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-rw-r--r--gl/fd-hook.c116
1 files changed, 116 insertions, 0 deletions
diff --git a/gl/fd-hook.c b/gl/fd-hook.c
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1/* Hook for making making file descriptor functions close(), ioctl() extensible.
2 Copyright (C) 2009-2013 Free Software Foundation, Inc.
3 Written by Bruno Haible <bruno@clisp.org>, 2009.
4
5 This program is free software: you can redistribute it and/or modify it
6 under the terms of the GNU General Public License as published
7 by the Free Software Foundation; either version 3 of the License, or
8 (at your option) any later version.
9
10 This program is distributed in the hope that it will be useful,
11 but WITHOUT ANY WARRANTY; without even the implied warranty of
12 MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
13 General Public License for more details.
14
15 You should have received a copy of the GNU General Public License
16 along with this program. If not, see <http://www.gnu.org/licenses/>. */
17
18#include <config.h>
19
20/* Specification. */
21#include "fd-hook.h"
22
23#include <stdlib.h>
24
25/* Currently, this entire code is only needed for the handling of sockets
26 on native Windows platforms. */
27#if WINDOWS_SOCKETS
28
29/* The first and last link in the doubly linked list.
30 Initially the list is empty. */
31static struct fd_hook anchor = { &anchor, &anchor, NULL, NULL };
32
33int
34execute_close_hooks (const struct fd_hook *remaining_list, gl_close_fn primary,
35 int fd)
36{
37 if (remaining_list == &anchor)
38 /* End of list reached. */
39 return primary (fd);
40 else
41 return remaining_list->private_close_fn (remaining_list->private_next,
42 primary, fd);
43}
44
45int
46execute_all_close_hooks (gl_close_fn primary, int fd)
47{
48 return execute_close_hooks (anchor.private_next, primary, fd);
49}
50
51int
52execute_ioctl_hooks (const struct fd_hook *remaining_list, gl_ioctl_fn primary,
53 int fd, int request, void *arg)
54{
55 if (remaining_list == &anchor)
56 /* End of list reached. */
57 return primary (fd, request, arg);
58 else
59 return remaining_list->private_ioctl_fn (remaining_list->private_next,
60 primary, fd, request, arg);
61}
62
63int
64execute_all_ioctl_hooks (gl_ioctl_fn primary,
65 int fd, int request, void *arg)
66{
67 return execute_ioctl_hooks (anchor.private_next, primary, fd, request, arg);
68}
69
70void
71register_fd_hook (close_hook_fn close_hook, ioctl_hook_fn ioctl_hook, struct fd_hook *link)
72{
73 if (close_hook == NULL)
74 close_hook = execute_close_hooks;
75 if (ioctl_hook == NULL)
76 ioctl_hook = execute_ioctl_hooks;
77
78 if (link->private_next == NULL && link->private_prev == NULL)
79 {
80 /* Add the link to the doubly linked list. */
81 link->private_next = anchor.private_next;
82 link->private_prev = &anchor;
83 link->private_close_fn = close_hook;
84 link->private_ioctl_fn = ioctl_hook;
85 anchor.private_next->private_prev = link;
86 anchor.private_next = link;
87 }
88 else
89 {
90 /* The link is already in use. */
91 if (link->private_close_fn != close_hook
92 || link->private_ioctl_fn != ioctl_hook)
93 abort ();
94 }
95}
96
97void
98unregister_fd_hook (struct fd_hook *link)
99{
100 struct fd_hook *next = link->private_next;
101 struct fd_hook *prev = link->private_prev;
102
103 if (next != NULL && prev != NULL)
104 {
105 /* The link is in use. Remove it from the doubly linked list. */
106 prev->private_next = next;
107 next->private_prev = prev;
108 /* Clear the link, to mark it unused. */
109 link->private_next = NULL;
110 link->private_prev = NULL;
111 link->private_close_fn = NULL;
112 link->private_ioctl_fn = NULL;
113 }
114}
115
116#endif