From da6f343032cb01597dc7866e66f091adf3243a62 Mon Sep 17 00:00:00 2001 From: Michael Smith Date: Sat, 20 Nov 2021 03:10:50 +0000 Subject: Initial public snapshot With code from Bill. Thanks Bill! --- src/hook.h | 54 ++++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 54 insertions(+) create mode 100644 src/hook.h (limited to 'src/hook.h') diff --git a/src/hook.h b/src/hook.h new file mode 100644 index 0000000..02c41dc --- /dev/null +++ b/src/hook.h @@ -0,0 +1,54 @@ +/* + * Copyright © 2021 Michael Smith + * + * Permission to use, copy, modify, and/or distribute this software for any + * purpose with or without fee is hereby granted, provided that the above + * copyright notice and this permission notice appear in all copies. + * + * THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH + * REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY + * AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, + * INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM + * LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR + * OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR + * PERFORMANCE OF THIS SOFTWARE. + */ + +#ifndef INC_HOOK_H +#define INC_HOOK_H + +#include "intdefs.h" + +/* + * Replaces a vtable entry with a target function and returns the original + * function. + */ +static inline void *hook_vtable(void **vtable, usize off, void *target) { + void *orig = vtable[off]; + vtable[off] = target; + return orig; +} + +/* + * Puts an original function back after hooking. + */ +static inline void unhook_vtable(void **vtable, usize off, void *orig) { + vtable[off] = orig; +} + +/* + * Returns a trampoline pointer, or null if hooking failed. Unlike hook_vtable, + * handles memory protection for you. + */ +void *hook_inline(void *func, void *target); + +/* + * Reverts the function to its original unhooked state. Takes the pointer to the + * callable "original" function, i.e. the trampoline, NOT the initial function + * pointer from before hooking. + */ +void unhook_inline(void *orig); + +#endif + +// vi: sw=4 ts=4 noet tw=80 cc=80 -- cgit v1.2.3