Files
CoopAllTheThings/hook/src/hook_install.hpp
BlackMark 635ef51283 Deduplicate the hook DLL and scrub history from its comments
Consolidate four copies of the keyed-mutex shared-texture setup
(present/opengl/d3d9/vk_capture) into one RAII SharedVideoTexture,
two copies of find_main_window into find_window.hpp, audio_hook's
hand-rolled detour guard into the shared DetourGate, the duplicated
vtable_method into vtable_hook.hpp, and the near-identical
Present/Present1 and SwapBuffers/wglSwapBuffers detour pairs into one
shared body each. The vk_layer and vk_capture_perf_test targets now
compile debug_log.cpp since the shared texture code logs.

Comments no longer narrate the past: drop stress-test/game anecdotes,
"used to"/"the old model" phrasing, plan-step labels, and pointers to
docs that do not exist; fix present_hook.hpp/opengl_hook.hpp claims
that predate the D3D12/D3D9/Vulkan backends. Net -266 lines, no
behavior change (full x64 + x86 suites pass, including the mock-game
hook/unhook storm).
2026-07-12 08:53:58 +02:00

52 lines
2.5 KiB
C++

// Safe INSTALL of a SafetyHook inline hook -- the symmetric partner of hook_guard.hpp's safe removal.
//
// Two problems this avoids, both hit when a game polls a hooked API at thousands of calls/s while
// the subsystem is toggled on/off (mock_game_test's hook/unhook storm exercises exactly that):
//
// 1. Enable-before-assign. create_inline() builds the hook AND enables it (patches the target's bytes
// to jump to the detour), THEN the result is move-assigned into the global the detour reads to
// reach the trampoline. A call landing in the detour during that assign reads a torn global -> AV.
// So we create StartDisabled, let dst be populated, and only THEN enable().
//
// 2. Trampoline use-after-free on re-install. Recreating the hook on every install and destroying
// it on every remove (= {}) frees the trampoline. A detour that has entered but not yet reached
// its DetourGate::Guard (the unguarded prologue) can then call a freed trampoline -> AV at a
// garbage address. drain() narrows that window but can't fully close it under heavy
// preemption. So instead we treat hooks as PERSISTENT: create each once and thereafter only
// enable()/disable() it across install/remove cycles. The trampoline is allocated once and never
// freed during the session, so a stale detour always calls a live trampoline (which, when
// disabled, simply runs the original). No churn, no leak (it's reused), no UAF. Removal therefore
// disable()s the hook (and drains) but does NOT destroy it (see hook_guard.hpp).
#pragma once
#include <safetyhook.hpp>
#include <windows.h>
namespace coop::hook
{
// Arm `detour` over `target` in `dst`: create it once (StartDisabled) if empty, then enable. Calling
// this again after a remove just re-enables the SAME hook (no recreate -> the trampoline is never
// freed). enable()'s [[nodiscard]] result is surfaced, not discarded; enabling an already-enabled
// hook is a no-op success.
inline void install_inline(safetyhook::InlineHook& dst, void* target, void* detour)
{
if (!dst) // create only the first time; reuse across enable/disable cycles
{
dst = safetyhook::create_inline(target, detour, safetyhook::InlineHook::StartDisabled);
}
if (dst && !dst.enable())
{
OutputDebugStringA("coop: SafetyHook InlineHook::enable() failed during install\n");
}
}
template <class T, class D>
void install_inline(safetyhook::InlineHook& dst, T target, D detour)
{
install_inline(dst, reinterpret_cast<void*>(target), reinterpret_cast<void*>(detour));
}
} // namespace coop::hook