1 /* Hook for making making file descriptor functions close(), ioctl() extensible. 2 Copyright (C) 2009-2012 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 execute_close_hooks(const struct fd_hook * remaining_list,gl_close_fn primary,int fd)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 execute_all_close_hooks(gl_close_fn primary,int fd)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 execute_ioctl_hooks(const struct fd_hook * remaining_list,gl_ioctl_fn primary,int fd,int request,void * arg)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 execute_all_ioctl_hooks(gl_ioctl_fn primary,int fd,int request,void * arg)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 register_fd_hook(close_hook_fn close_hook,ioctl_hook_fn ioctl_hook,struct fd_hook * link)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 unregister_fd_hook(struct fd_hook * link)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 117