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6ec2e0f5 SDJ |
1 | /* Hook for making making file descriptor functions close(), ioctl() extensible. |
2 | Copyright (C) 2009-2016 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. */ | |
31 | static struct fd_hook anchor = { &anchor, &anchor, NULL, NULL }; | |
32 | ||
33 | int | |
34 | execute_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 | ||
45 | int | |
46 | execute_all_close_hooks (gl_close_fn primary, int fd) | |
47 | { | |
48 | return execute_close_hooks (anchor.private_next, primary, fd); | |
49 | } | |
50 | ||
51 | int | |
52 | execute_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 | ||
63 | int | |
64 | execute_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 | ||
70 | void | |
71 | register_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 | ||
97 | void | |
98 | unregister_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 |