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-rw-r--r--gl/close-hook.c91
1 files changed, 91 insertions, 0 deletions
diff --git a/gl/close-hook.c b/gl/close-hook.c
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1/* Hook for making the close() function extensible.
2 Copyright (C) 2009, 2010 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 Lesser 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 "close-hook.h"
22
23#include <stdlib.h>
24#include <unistd.h>
25
26#undef close
27
28
29/* Currently, this entire code is only needed for the handling of sockets
30 on native Windows platforms. */
31#if WINDOWS_SOCKETS
32
33/* The first and last link in the doubly linked list.
34 Initially the list is empty. */
35static struct close_hook anchor = { &anchor, &anchor, NULL };
36
37int
38execute_close_hooks (int fd, const struct close_hook *remaining_list)
39{
40 if (remaining_list == &anchor)
41 /* End of list reached. */
42 return close (fd);
43 else
44 return remaining_list->private_fn (fd, remaining_list->private_next);
45}
46
47int
48execute_all_close_hooks (int fd)
49{
50 return execute_close_hooks (fd, anchor.private_next);
51}
52
53void
54register_close_hook (close_hook_fn hook, struct close_hook *link)
55{
56 if (link->private_next == NULL && link->private_prev == NULL)
57 {
58 /* Add the link to the doubly linked list. */
59 link->private_next = anchor.private_next;
60 link->private_prev = &anchor;
61 link->private_fn = hook;
62 anchor.private_next->private_prev = link;
63 anchor.private_next = link;
64 }
65 else
66 {
67 /* The link is already in use. */
68 if (link->private_fn != hook)
69 abort ();
70 }
71}
72
73void
74unregister_close_hook (struct close_hook *link)
75{
76 struct close_hook *next = link->private_next;
77 struct close_hook *prev = link->private_prev;
78
79 if (next != NULL && prev != NULL)
80 {
81 /* The link is in use. Remove it from the doubly linked list. */
82 prev->private_next = next;
83 next->private_prev = prev;
84 /* Clear the link, to mark it unused. */
85 link->private_next = NULL;
86 link->private_prev = NULL;
87 link->private_fn = NULL;
88 }
89}
90
91#endif