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+/* Hook for making file descriptor functions close(), ioctl() extensible.
+ Copyright (C) 2009-2022 Free Software Foundation, Inc.
+
+ This file is free software: you can redistribute it and/or modify
+ it under the terms of the GNU Lesser General Public License as
+ published by the Free Software Foundation; either version 2.1 of the
+ License, or (at your option) any later version.
+
+ This file is distributed in the hope that it will be useful,
+ but WITHOUT ANY WARRANTY; without even the implied warranty of
+ MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+ GNU Lesser General Public License for more details.
+
+ You should have received a copy of the GNU Lesser General Public License
+ along with this program. If not, see <https://www.gnu.org/licenses/>. */
+
+
+#ifndef FD_HOOK_H
+#define FD_HOOK_H
+
+#ifdef __cplusplus
+extern "C" {
+#endif
+
+
+/* Currently, this entire code is only needed for the handling of sockets
+ on native Windows platforms. */
+#if WINDOWS_SOCKETS
+
+
+/* Type of function that closes FD. */
+typedef int (*gl_close_fn) (int fd);
+
+/* Type of function that applies a control request to FD. */
+typedef int (*gl_ioctl_fn) (int fd, int request, void *arg);
+
+/* An element of the list of file descriptor hooks.
+ In CLOS (Common Lisp Object System) speak, it consists of an "around"
+ method for the close() function and an "around" method for the ioctl()
+ function.
+ The fields of this structure are considered private. */
+struct fd_hook
+{
+ /* Doubly linked list. */
+ struct fd_hook *private_next;
+ struct fd_hook *private_prev;
+ /* Function that treats the types of FD that it knows about and calls
+ execute_close_hooks (REMAINING_LIST, PRIMARY, FD) as a fallback. */
+ int (*private_close_fn) (const struct fd_hook *remaining_list,
+ gl_close_fn primary,
+ int fd);
+ /* Function that treats the types of FD that it knows about and calls
+ execute_ioctl_hooks (REMAINING_LIST, PRIMARY, FD, REQUEST, ARG) as a
+ fallback. */
+ int (*private_ioctl_fn) (const struct fd_hook *remaining_list,
+ gl_ioctl_fn primary,
+ int fd, int request, void *arg);
+};
+
+/* This type of function closes FD, applying special knowledge for the FD
+ types it knows about, and calls
+ execute_close_hooks (REMAINING_LIST, PRIMARY, FD)
+ for the other FD types.
+ In CLOS speak, REMAINING_LIST is the remaining list of "around" methods,
+ and PRIMARY is the "primary" method for close(). */
+typedef int (*close_hook_fn) (const struct fd_hook *remaining_list,
+ gl_close_fn primary,
+ int fd);
+
+/* Execute the close hooks in REMAINING_LIST, with PRIMARY as "primary" method.
+ Return 0 or -1, like close() would do. */
+extern int execute_close_hooks (const struct fd_hook *remaining_list,
+ gl_close_fn primary,
+ int fd);
+
+/* Execute all close hooks, with PRIMARY as "primary" method.
+ Return 0 or -1, like close() would do. */
+extern int execute_all_close_hooks (gl_close_fn primary, int fd);
+
+/* This type of function applies a control request to FD, applying special
+ knowledge for the FD types it knows about, and calls
+ execute_ioctl_hooks (REMAINING_LIST, PRIMARY, FD, REQUEST, ARG)
+ for the other FD types.
+ In CLOS speak, REMAINING_LIST is the remaining list of "around" methods,
+ and PRIMARY is the "primary" method for ioctl(). */
+typedef int (*ioctl_hook_fn) (const struct fd_hook *remaining_list,
+ gl_ioctl_fn primary,
+ int fd, int request, void *arg);
+
+/* Execute the ioctl hooks in REMAINING_LIST, with PRIMARY as "primary" method.
+ Return 0 or -1, like ioctl() would do. */
+extern int execute_ioctl_hooks (const struct fd_hook *remaining_list,
+ gl_ioctl_fn primary,
+ int fd, int request, void *arg);
+
+/* Execute all ioctl hooks, with PRIMARY as "primary" method.
+ Return 0 or -1, like ioctl() would do. */
+extern int execute_all_ioctl_hooks (gl_ioctl_fn primary,
+ int fd, int request, void *arg);
+
+/* Add a function pair to the list of file descriptor hooks.
+ CLOSE_HOOK and IOCTL_HOOK may be NULL, indicating no change.
+ The LINK variable points to a piece of memory which is guaranteed to be
+ accessible until the corresponding call to unregister_fd_hook. */
+extern void register_fd_hook (close_hook_fn close_hook, ioctl_hook_fn ioctl_hook,
+ struct fd_hook *link);
+
+/* Removes a hook from the list of file descriptor hooks. */
+extern void unregister_fd_hook (struct fd_hook *link);
+
+
+#endif
+
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif /* FD_HOOK_H */