| 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 |